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Short vs. Long Rest Period Between the Sets in Hypertrophic Resistance Training: Influence on Muscle Strength, Size, and Hormonal Adaptations in Trained Men
Abstract
Acute and long-term hormonal and neuromuscular adaptations to hypertrophic strength training were studied in 13 recreationally strength-trained men. The experimental design comprised a 6-month hypertrophic strength-training period including 2 separate 3-month training periods with the crossover design, a training protocol of short rest (SR, 2 minutes) as compared with long rest (LR, 5 minutes) between the sets. Basal hormonal concentrations of serum total testosterone (T), free testosterone (FT), and cortisol (C), maximal isometric strength of the leg extensors, right leg 1 repetition maximum (1RM), dietary analysis, and muscle cross-sectional area (CSA) of the quadriceps femoris by magnetic resonance imaging (MRI) were measured at months 0, 3, and 6. The 2 hypertrophic training protocols used in training for the leg extensors (leg presses and squats with 10RM sets) were also examined in the laboratory conditions at months 0, 3, and 6. The exercise protocols were similar with regard to the total volume of work (loads x sets x reps), but differed with regard to the intensity and the length of rest between the sets (higher intensity and longer rest of 5 minutes vs. somewhat lower intensity but shorter rest of 2 minutes). Before and immediately after the protocols, maximal isometric force and electromyographic (EMG) activity of the leg extensors were measured and blood samples were drawn for determination of serum T, FT, C, and growth hormone (GH) concentrations and blood lactate. Both protocols before the experimental training period (month 0) led to large acute increases (p < 0.05-0.001) in serum T, FT, C , and GH concentrations, as well as to large acute decreases (p < 0.05-0.001) in maximal isometric force and EMG activity. However, no significant differences were observed between the protocols. Significant increases of 7% in maximal isometric force, 16% in the right leg 1RM, and 4% in the muscle CSA of the quadriceps femoris were observed during the 6-month strength-training period. However, both 3-month training periods performed with either the longer or the shorter rest periods between the sets resulted in similar gains in muscle mass and strength. No statistically significant changes were observed in basal hormone concentrations or in the profiles of acute hormonal responses during the entire 6-month experimental training period. The present study indicated that, within typical hypertrophic strength-training protocols used in the present study, the length of the recovery times between the sets (2 vs. 5 minutes) did not have an influence on the magnitude of acute hormonal and neuromuscular responses or long-term training adaptations in muscle strength and mass in previously strength-trained men.
... The observed relationship between anabolic hormones and exercise has led to the hormone hypothesis, which assumes that the acute exercise-induced elevations in anabolic hormones are associated with increased muscle strength and hypertrophy [6,[10][11][12][13]. Research is still contradictory as to whether or not the acute hormonal response is associated with muscle hypertrophy, but some studies suggest that the acute exercise-induced GH response correlates with the magnitude of muscle fiber hypertrophy [6,12,13]. ...
... Some studies have focused their attention on the effect of different strength training protocols on the secretion of anabolic and catabolic hormones [11,[20][21][22], while some others have investigated the effect of different endurance or sprint exercise protocols on hormonal secretions [23,24]. Nevertheless, there is scarce research investigating the acute GH response to strength and sprint concurrent training [15,25], and most of the studies on hormonal responses to concurrent training have been devoted to strength and endurance protocols [26][27][28][29][30][31]. ...
... Although the GH response to strength training in both STS and SPS orders was not significant, it was close to the significance level and would probably reach the significance level with a higher number of subjects. The strength training in the present study was designed based on the previous findings which advise the use of moderate intensity (about 10RM), short rest intervals (about 1 min), and stressing a large muscle mass to elicit the best GH response [11,21,35,36]. Nevertheless, there is apparently a specific threshold regarding the interaction between the volume and the intensity of the performed work [25,37]. ...
Purpose
The purpose of this study was to investigate the effect of the intra-session order of concurrent strength-sprint training on the acute growth hormone response.
Methods
Nine strength-trained students (age 24.1 ± 4.1) performed two different concurrent exercise orders: strength–sprint (STS) and sprint–strength (SPS). Strength training consisted of three sets of ten repetitions with 10RM for four exercises: bench press, lat pulldown, squat and shoulder press. Sprint exercise consisted of eight repetitions of 30-m maximal sprint running with 45-s rest periods between repetitions. In both exercise orders, the subjects rested for 10 min after the completion of the first part of the concurrent training session. Blood samples were collected before, between exercise modalities, and immediately after the concurrent training sessions.
Results
A significant increase in growth hormone levels occurred in response to single sessions of concurrent strength–sprint training, but no significant difference was observed between the two different orders of concurrent training (STS vs. SPS) regarding the acute growth hormone response.
Conclusions
In general, performing sprint training before or after strength training not only imposes no inhibitory effect on the growth hormone response to strength training, but also increases the hormone’s overall response.
... However, results of longitudinal studies on the topic are conflicting, with some studies showing advantage for LI on strength increases (13,23) and hypertrophy (4,8,23), while others failing to demonstrate any difference for strength (2,4,8,16) and hypertrophy (2,13,18) between LI and SI. Such discrepancies may be attributed to heterogeneity in the experimental designs. ...
... However, results of longitudinal studies on the topic are conflicting, with some studies showing advantage for LI on strength increases (13,23) and hypertrophy (4,8,23), while others failing to demonstrate any difference for strength (2,4,8,16) and hypertrophy (2,13,18) between LI and SI. Such discrepancies may be attributed to heterogeneity in the experimental designs. ...
... Such discrepancies may be attributed to heterogeneity in the experimental designs. For example, Hill-Hass et al. (13) compared rest intervals of 20 and 80 seconds; Fink et al. (8) compared 30 seconds vs. 3 minutes; Schoenfeld et al. (23) compared 60 seconds vs. 3 minutes, and Ahtiainen et al. (2) compared 2 minutes vs. 5 minutes. Moreover, various issues may have confounded some of these studies. ...
Longo, AR, Silva-Batista, C, Pedroso, K, de Salles Painelli, V, Lasevicius, T, Schoenfeld, BJ, Aihara, AY, de Almeida Peres, B, Tricoli, V, and Teixeira, EL. Volume load rather than resting interval influences muscle hypertrophy during high-intensity resistance training. J Strength Cond Res 36(6): 1554-1559, 2022-Interset rest interval has been proposed as an important variable for inducing muscle mass and strength increases during resistance training. However, its influence remains unclear, especially when protocols with differing intervals have equalized volume. We aimed to compare the effects of long (LI) vs. short rest interval (SI) on muscle strength (one repetition maximum [1RM]) and quadriceps cross-sectional area (QCSA), with or without equalized volume load (VL). Twenty-eight subjects trained twice a week for 10 weeks. Each subject's leg was allocated to 1 of 4 unilateral knee extension protocols: LI, SI, SI with VL -matched by LI (VLI-SI), and LI with VL-matched by SI (VSI-LI). A 3-minute rest interval was afforded in LI and VSI-LI protocols, while SI and VLI-SI employed a 1-minute interval. All subjects trained with a load corresponding to 80% 1RM. One repetition maximum and QCSA were measured before and after training. All protocols significantly increased 1RM values in post-training (p < 0.0001; LI: 27.6%, effect size [ES] = 0.90; VLI-SI: 31.1%, ES = 1.00; SI: 26.5%, ES = 1.11; and VSI-LI: 31.2%, ES = 1.28), with no significant differences between protocols. Quadriceps cross-sectional area increased significantly for all protocols in post-training (p < 0.0001). However, absolute changes in QCSA were significantly greater in LI and VLI-SI (13.1%, ES: 0.66 and 12.9%, ES: 0.63) than SI and VSI-LI (6.8%, ES: 0.38 and 6.6%, ES: 0.37) (both comparisons, p < 0.05). These data suggest that maintenance of high loads is more important for strength increases, while a greater VL plays a primary role for hypertrophy, regardless of interset rest interval.
... However, results of longitudinal studies on the topic are conflicting, with some studies showing advantage for LI on strength increases (13,23) and hypertrophy (4,8,23), while others failing to demonstrate any difference for strength (2,4,8,16) and hypertrophy (2,13,18) between LI and SI. Such discrepancies may be attributed to heterogeneity in the experimental designs. ...
... However, results of longitudinal studies on the topic are conflicting, with some studies showing advantage for LI on strength increases (13,23) and hypertrophy (4,8,23), while others failing to demonstrate any difference for strength (2,4,8,16) and hypertrophy (2,13,18) between LI and SI. Such discrepancies may be attributed to heterogeneity in the experimental designs. ...
... Such discrepancies may be attributed to heterogeneity in the experimental designs. For example, Hill-Hass et al. (13) compared rest intervals of 20 and 80 seconds; Fink et al. (8) compared 30 seconds vs. 3 minutes; Schoenfeld et al. (23) compared 60 seconds vs. 3 minutes, and Ahtiainen et al. (2) compared 2 minutes vs. 5 minutes. Moreover, various issues may have confounded some of these studies. ...
... Resistance training guidelines recommend inter-set rest of long (>2 min) rather than short (<1 min) duration to increase muscle strength (Hill-Haas, Bishop, Dawson, Goodman, & Edge, 2007;Schoenfeld, Pope, et al., 2016;Schoenfeld, Wilson, Lowery, & Krieger, 2016). However, some studies show similar strength increases regardless of the inter-set rest (Ahtiainen, Pakarinen, Alen, Kraemer, & Häkkinen, 2005;Buresh, Berg, & French, 2009;Fink, Schoenfeld, Kikuchi, & Nakazato, 2017;MacInnis, McGlory, Gibala, & Phillips, 2017), but others show higher strength increases when using short inter-set rests (Villanueva, Lane, & Schroeder, 2015). Such inconsistencies could be due to differences in the prescription of training variables and sample groups. ...
... Such inconsistencies could be due to differences in the prescription of training variables and sample groups. Regarding training variables, studies exclusively investigated different durations of short (20 seconds to 1 min) and long (80 seconds to 5 min) rest intervals (Ahtiainen, et al., 2005;Fink, et al., 2017;Hill-Haas, et al., 2007) and differed between conditions for relative load, proximity to muscle failure and volume load (Buresh, et al., 2009;Fink, et al., 2017;Schoenfeld, Pope, et al., 2016). Regarding sample groups, some studies investigated physically inactive elderly persons (Villanueva, et al., 2015) or resistance-untrained individuals (Buresh, et al., 2009;Fink, et al., 2017;Piirainen, et al., 2011). ...
Resistance training is a widely used method to enhance muscle strength, with acute program variables influencing muscle adaptations. This study focused on the often-neglected variable of inter-set rest interval duration and its impact on muscle strength gains. Existing literature presents conflicting findings, with some studies advocating for longer rest intervals, while the others show comparable strength increases with shorter rests. Methodological differences in prescription and sample groups contributed to these inconsistencies. This study investigated the effect of short and long inter-set rests on maximal isokinetic strength gains of the upper and lower extremities during slow and fast angular velocities after eight weeks of resistance training. The research involved 26 healthy strength-trained males (age=20±1 year, body mass=81.5±8.8 kg, body height=184.4±6.1 cm) randomly assigned to G1m (1-minute rest) or G3m (3-minute rest). The resistance training programs were matched for all acute program variables, emphasizing the rest interval as the primary difference. Isokinetic dynamometry pre- and post-training assessed knee and elbow extensor and flexor maximal strength at 60º/s and 120º/s. The training program consisted of seven exercises performed at 70% 1RM until muscle failure three times per week over eight weeks. The most important result was that G3m, in contrast to G1m, led to a higher increase in peak torque of the knee (p=.037) and elbow extensors (p=.007) as well as the elbow flexors (p=.045) at 60º/s. Furthermore, G3m and G1m similarly increased the peak torque of the knee and elbow extensors and flexors at 120º/s and of the knee flexors at 60º/s (p>.138). In conclusion, the study suggests that strength training with longer inter-set rest intervals may lead to similar strength gains as strength training with shorter inter-set rest intervals. Nonetheless, individuals who prioritize maximizing their strength gains are advised to utilize longer rest intervals. However, shorter rest intervals may still yield significant strength enhancements, particularly for those who are limited by time.
... The results of the meta analysis demonstrated a positive effect in the groups that used RI> 2 minutes, as this generated a greater number of repetitions and, consequently, a greater volume of training, which can stimulate physiological responses associated with signaling pathways of muscle hypertrophy, resulting in an increase of strength and muscle mass. 23,24 These results are consistent with the study by Senna et al, 2016, 8 which compared several RIs between sets with the supine and crucifix exercise and found a greater number of repetitions in the 2-minute intervals (12.60 ± 2.35 repetitions; p = 0.027), 3 minutes (13.66 ± 1.84 repetitions; p = 0.001) and 5 minutes (12.93 ± 2.25 representatives; p = 0.001) vs. 1-minute protocol (10.33 ± 2.60 repetitions). From the results in the present study, it is clear that the longer RI promotes greater training volume. ...
... Considering that both the volume and the intensity of training are variables that are directly related to the stimulation of neuromuscular adaptations, 25 it was speculated that longer rests could provide greater volumes of training compared to 2 minutes, contrary to the data obtained in the review by GRGIC. 26 Like AHTIAINEN, 23 who used RI of 2 and 5 minutes, but found no significant changes in the total training load during the training period. However, there was a significant increase of 6.8 ± 8.7% (from 3,370 ± 748 to 3,613 ± 949 N) (p, 0.05) in the maximum strength of the extensor chair in isometry in the total group of subjects. ...
Introduction
The recovery interval (RI) between sets and exercises has received attention from strength training (ST) researchers, to understand the relationship of rest on performance maintenance, especially the total load in a training session. It is known that each individual responds in a specific way to the training stimulus. So, what would be the effect of the different recovery interval strategies on the strength performance?
Objective
Compare the different recovery intervals in strength training volume, considering the number of repetitions in healthy adults.
Methods
We conducted a systematic review and meta-analysis based on methodological criteria, comparing fixed and self-selected RI on training volume, identified by the number of repetitions performed in a weight training program. Three electronic databases (Pubmed, VHL Virtual Health Library, Ebsco Sportdiscus) were analyzed, combining the expressions “resistance training”, “resistance exercise”, “strength exercise”, “recovery interval”, “rest interval”, “interval auto suggested”, “auto range selected” with “AND” and “OR” combination.
Results
Pooled data from five studies showed a large significant effect in favor of the experimental group (>2 minutes) (MD: 1.24; 95%-CI [0.78; 1.71]; z: 5.25, Q:1.08; p < 0.01), since in the studies, recovery interval allowed a greater training volume.
Conclusion
Longer RI seems be better, for maintaining total training volume, although there is no consensus for different training objectives against the self-selected RI. Thus, we imagine that this strategy may be important in the organizing a bodybuilding exercise program. Level of Evidence I; Systematic Review and Meta Analysis.
Keywords:
Resistance Training; Rest; Health Strategies
... It is well known that periods of inactivity generate a loss of muscle strength, a fundamental component of sports performance in soccer [4][5][6][7][8][9][10]. However, little information is available on the decrease in strength levels of professional soccer players after the quarantine period applied during COVID-19 pandemic [11][12][13][14][15]. ...
... All subjects were submitted to a testing protocol following the guidelines of the APTA (American Physical erapy Association) [4,[22][23][24] and soccer-specific studies using isokinetic machines [25][26][27]. e same physiotherapist, with 10 years of experience, performed all the isokinetic tests. ...
Background:
It is well known that periods of inactivity generate a loss of muscle strength, a fundamental component of sports performance in soccer. However, little information is available on the decrease in strength levels in professional soccer players after the quarantine lockdown that occurred during the COVID-19 pandemic.
Aim:
To compare the isokinetic peak torque profiles of professional soccer players from different teams before and after the quarantine period generated by COVID-19.
Methods:
A retrospective observational study was performed using data collected from two different professional elite-level soccer teams just before and immediately after the COVID-19 quarantine period. One team gave individual instructions to its players for conditioning maintenance at home during the quarantine period, while the other team used regular video calls to maintain the player's conditioning status on home training. The main outcomes were the mean peak torque of knee extensors and flexors, from concentric and eccentric contractions of each playing position. Analysis. A two-way ANOVA analysis was used to compare peak torque before and after the quarantine period and between both teams' strategies, showing a statistically significant reduction in eccentric knee flexor peak torque from the team that did not have remote monitoring.
Conclusions:
Remote monitoring programs are recommended so that athletes are less affected by the deleterious effects of confinement.
... Os períodos de descanso têm influência na determinação do estresse do treino e no total da carga que pode ser manipulada. Alguns estudos 1,10,12,18,19 têm demonstrado, que o tempo de intervalo entre as séries, tem um efeito significativo sobre o volume total completado durante uma seqüência de um determinado exercício, o que conseqüentemente pode afetar o desenvolvimento da força e hipertrofia 1,16 . No entanto, os resultados ainda são escassos, não permitindo inferências consistentes sobre o tempo adequado de recuperação entre as séries e exercícios, para otimizarem objetivos diversificados na prescrição. ...
... Os períodos de descanso têm influência na determinação do estresse do treino e no total da carga que pode ser manipulada. Alguns estudos 1,10,12,18,19 têm demonstrado, que o tempo de intervalo entre as séries, tem um efeito significativo sobre o volume total completado durante uma seqüência de um determinado exercício, o que conseqüentemente pode afetar o desenvolvimento da força e hipertrofia 1,16 . No entanto, os resultados ainda são escassos, não permitindo inferências consistentes sobre o tempo adequado de recuperação entre as séries e exercícios, para otimizarem objetivos diversificados na prescrição. ...
... The relationship between RE and testosterone responses have been extensively reviewed in young men (Ahtiainen et al., 2003(Ahtiainen et al., , 2005West et al., 2009;West and Phillips, 2012), with the majority of studies suggesting that it is the acute transient elevations in testosterone that likely drive the proposed hormonal adaptations associated with muscle growth. For example, immediately following RE, serum testosterone levels peak [∼from 13 (resting levels) to 38 (at ∼30 mins) nmol.L −1 ] with a concomitant upregulation of AR mRNA and protein content within the muscle (Willoughby and Taylor, 2004;Hooper et al., 2017). ...
... It therefore may be that the combined effects of acute testosterone elevation post exercise and sustained AR upregulation in the muscle may represent an additional mechanism through which RE might regulate muscle growth. Notably, while some studies have indicated correlative relationships between RE-induced elevations in testosterone and muscle strength and hypertrophy (Hansen et al., 2001;Ahtiainen et al., 2003Ahtiainen et al., , 2005, this remains equivocal (West et al., 2009;West and Phillips, 2012) perhaps since the magnitude of acute responses in young males can be influenced by many factors e.g., timing of sampling etc. Additionally, there is evidence that RE loads of <70% 1-RM (Tremblay et al., 2004;Yarrow et al., 2007;Fry and Lohnes, 2010;Hough et al., 2011); programs incorporating only upper body exercises, even at a relatively high intensity and volume (Migiano et al., 2010); and those with the long rest periods between repetitions do not stimulate a significant post exercise testosterone response (McCaulley et al., 2009), despite post exercise increases in MPS, anabolic signaling and associated muscle growth adaptive responses being observed (West et al., 2009;West and Phillips, 2012). ...
Maintenance of skeletal muscle mass throughout the life course is key for the regulation of health, with physical activity a critical component of this, in part, due to its influence upon key hormones such as testosterone, estrogen, growth hormone (GH), and insulin-like growth factor (IGF). Despite the importance of these hormones for the regulation of skeletal muscle mass in response to different types of exercise, their interaction with the processes controlling muscle mass remain unclear. This review presents evidence on the importance of these hormones in the regulation of skeletal muscle mass and their responses, and involvement in muscle adaptation to resistance exercise. Highlighting the key role testosterone plays as a primary anabolic hormone in muscle adaptation following exercise training, through its interaction with anabolic signaling pathways and other hormones via the androgen receptor (AR), this review also describes the potential importance of fluctuations in other hormones such as GH and IGF-1 in concert with dietary amino acid availability; and the role of estrogen, under the influence of the menstrual cycle and menopause, being especially important in adaptive exercise responses in women. Finally, the downstream mechanisms by which these hormones impact regulation of muscle protein turnover (synthesis and breakdown), and thus muscle mass are discussed. Advances in our understanding of hormones that impact protein turnover throughout life offers great relevance, not just for athletes, but also for the general and clinical populations alike.
... Henselmans and Schoenfeld (118) stated correctly that there was no significant difference between the two 3-month training protocols (2 min or 5 min interset rest) for muscle hypertrophy (120). However, they neglected to state that the trainees did not significantly increase thigh muscle mass during either of the two 3-month periods (1.8 and 1.8%, respectively). ...
... Ahtiainen and colleagues (120) concluded that shorter or longer interset rest intervals did not influence the magnitude of muscle hypertrophy, and that the different number of sets or the amount of resistance during each 3-month period also had no significant effect on the degree of muscle hypertrophy. In a systematic review, Grgic and colleagues (121) claimed that their results suggested that longer inter--set rest intervals may have an advantage over shorter rest intervals for eliciting muscular hypertrophy in previously trained subjects. ...
Researchers have expressed concern recently for standardization of resistance training protocols so that valid comparisons of different training variables such as muscular fatigue, time under tension, pre-exhaust exercise and exercise order, pyramid and drop sets, amount of resistance (load), range of repetitions, frequency and volume of exercise, interset rest intervals, etc. can be more closely studied and compared. This Critical Commentary addresses some recent review articles and training studies specifically focused on the stimulus for muscle hypertrophy in participants with several years of resistance training experience. It reveals that many of the recommended resistance training protocols have their foundation in some long-held, self-described bias. Blinding of assessors and statisticians, self-plagiarism, authorship responsibility, and conflicts of interest are briefly discussed as well. The conclusion is that most of the published peer-reviewed resistance training literature failed to provide any compelling evidence that the manipulation of any one or combination of the aforementioned variables can significantly affect the degree of muscle hypertrophy, especially in well-trained participants. Although the specific stimulus for optimal gains in muscle mass is unknown, many authors are desperately clinging to their unsupported belief that a greater volume of exercise will produce superior muscle hypertrophy.
... Henselmans and Schoenfeld (118) stated correctly that there was no significant difference between the two 3-month training protocols (2 min or 5 min interset rest) for muscle hypertrophy (120). However, they neglected to state that the trainees did not significantly increase thigh muscle mass during either of the two 3-month periods (1.8 and 1.8%, respectively). ...
... Ahtiainen and colleagues (120) concluded that shorter or longer interset rest intervals did not influence the magnitude of muscle hypertrophy, and that the different number of sets or the amount of resistance during each 3-month period also had no significant effect on the degree of muscle hypertrophy. ...
Researchers have expressed concern recently for standardization of resistance training protocols so that valid comparisons of different training variables such as muscular fatigue, time under tension, pre-exhaust exercise and exercise order, pyramid and drop sets, amount of resistance (load), range of repetitions, frequency and volume of exercise, interset rest intervals, etc. can be more closely studied and compared. This Critical Commentary addresses some recent review articles and training studies specifically focused on the stimulus for muscle hypertrophy in participants with several years of resistance training experience. It reveals that many of the recommended resistance training protocols have their foundation in some long-held, self-described bias.
... Henselmans and Schoenfeld (118) stated correctly that there was no significant difference between the two 3-month training protocols (2 min or 5 min interset rest) for muscle hypertrophy (120). However, they neglected to state that the trainees did not significantly increase thigh muscle mass during either of the two 3-month periods (1.8 and 1.8%, respectively). ...
... Ahtiainen and colleagues (120) concluded that shorter or longer interset rest intervals did not influence the magnitude of muscle hypertrophy, and that the different number of sets or the amount of resistance during each 3-month period also had no significant effect on the degree of muscle hypertrophy. ...
Researchers have expressed concern recently for standardization of resistance training protocols so that valid comparisons of different training variables such as muscular fatigue, time under tension, pre-exhaust exercise and exercise order, pyramid and drop sets, amount of resistance (load), range of repetitions, frequency and volume of exercise, interset rest intervals, etc. can be more closely studied and compared. This Critical Commentary addresses some recent review articles and training studies specifically focused on the stimulus for muscle hypertrophy in participants with several years of resistance training experience. It reveals that many of the recommended resistance training protocols have their foundation in some long-held, self-described bias.
... The 12-week evaluation, which provides a thorough analysis of long-term neural and muscle changes, is the main indicator of the intervention's efficacy (Kraemer et al., 2002). Significant gains in strength and muscle hypertrophy are measured; these improvements usually show up after 8-12 weeks of regular exercise (Ahtiainen et al., 2005). By assessing after 12 weeks, it is ensured that the gains made during the training program are maintained and accurately reflect the program's adaptation (Häkkinen et al., 2000). ...
Overhead athletes are at a higher risk of injury when the internal rotation strength of their dominant shoulder exceeds that of the non-dominant shoulder by 9%, and the external rotation strength is 14% greater in the dominant shoulder compared to the non-dominant shoulder. Though 15% of bilateral strength difference is recognized in the literature as an imbalance. This study examined the effect of isometric exercise on muscle imbalance in young elite badminton players. The study was conducted using an experimental design with pre-test and post-test methodologies. We included approximately 80 Malaysian elite badminton players, comprising 42 male and 38 females, with an average age of 15 years and a maturity level of 2.05 peak height velocity. Participants were randomly assigned to two groups. The experimental group followed a 12-week internal and external rotation isometric exercise regimen. Three key measurements were tak-en during the study: pre-test data collected before any intervention, post-test1 data after 4 weeks of isometric exercises (12 sessions), and post-test2 data after 12 weeks of isometric exercises (36 sessions). A MicroFET®2 digital handheld dy-namometer was used to assess muscle imbalance, focusing on the internal and external rotations of the dominant and non-dominant shoulders. The results showed a significant improvement in the muscle imbalance of the experimental group. Post-tests 1 and 2 revealed considerable improvements in the muscle imbalance ratios (p<0.01Ƞ = 0.791, 0.807). Isometric exercises were found to significantly influence muscle imbalance (p<0.01; Ƞ = 0.769). This study established a positive and significant interaction between isometric exercise repetitions and muscle imbalance within the experimental group. Overall, the findings concluded that isometric exercises can significantly decrease muscle imbalance, with positive and significant effects observed even after just 4 weeks of the intervention in the treatment group.
... In contrast, strength development depends more on the intensity of the contraction, so the focus should be on increasing load. Rest intervals between sets vary according to the training goal: 3-5 minutes for strength, # 2 minutes for endurance, and 2-5 minutes for hypertrophy (3,80). Table 4 summarizes progressive resistance training recommendations. ...
Parkinson disease (PD) is a progressive and chronic neurodegenerative disorder that compromises both motor and nonmotor functions, ultimately leading to a decline in functional capacity and quality of life. Although the etiology of PD is multifaceted, exercise has shown promising effects in managing PD symptoms and enhancing patient well-being. Although aerobic and resistance exercise demonstrate benefits within this specific population, the exact application of these modalities varies and often differs depending on disease progression and the individual. Although individuals diagnosed with PD are encouraged to exercise, there is still a lack of information pertaining to how to successfully structure physical activity into their daily routine. There are also distinct barriers and motivators impacting their decision to engage in regular exercise. This manuscript offers practical recommendations and personalized exercise guidelines for exercise professionals, empowering them to optimize PD management through targeted exercise interventions. In addition, it offers current information on promoting exercise among patients with PD, specifically to enhance their functional outcomes.
... Resistance training increases myofibrillar volume, cytoplasmic density, and sarcoplasmic reticulum density, while decreasing mitochondrial density and capillary density relative to muscle area (40,41). Sprint training enhances calcium release, aiding in speed and power production (42). ...
This article concerns periodized and non-periodized training protocols, now widely used to enhance athletic performance conditioning. Periodization is a systematic training protocol that structures training into specific phases. Periodization directly involves optimizing performance results by changing training variables such as intensity, volume, and exercise selection interpretation over time. Periodized training systems are also widely used to manage fatigue levels and reach peak performance at certain moments. On the other hand, however, a non-periodized training outlook involves a regular interchange, where training variables remain unchanged or change consistently. It may offer a more straightforward and more uncomplicated way of approaching training sessions but, as a result, may lead to flat progress. Hence, to clarify a more transparent approach to enhancing performance, this review article provides a more comprehensive theoretical comparison in depth between these methodologies, to try to delve into both conceptual frameworks' understanding, advantages, disadvantages, limitations, and practical applications. This article also aims to represent more literature on the background. While trying to uncover some shadowed parts of the theoretical framework, this article examines some of the impact of periodized strength training on neuromuscular adaptation, muscle hypertrophy and other structural changes, supported by a review of key research findings. Furthermore, the historical development of periodization theory is discussed, outlining the evolution from early practices to contemporary models and assessing its relevance in modern athletic training. The comparison highlights how each approach influences performance, adaptation, and recovery, emphasizing the need for further research to better understand and apply these training methodologies in diverse athletic contexts. The review concludes that while periodization offers structured progression and helps prevent performance plateaus, non-periodized training provides flexibility and may suit specific training scenarios where simplicity is preferred.
... Resistance training increases myofibrillar volume, cytoplasmic density, and sarcoplasmic reticulum density, while decreasing mitochondrial density and capillary density relative to muscle area (40,41). Sprint training enhances calcium release, aiding in speed and power production (42). ...
This article concerns periodized and non-periodized training protocols, now widely used to enhance athletic performance conditioning. Periodization is a systematic training protocol that structures training into specific phases. Periodization directly involves optimizing performance results by changing training variables such as intensity, volume, and exercise selection interpretation over time. Periodized training systems are also widely used to manage fatigue levels and reach peak performance at certain moments. On the other hand, however, a non-periodized training outlook involves a regular interchange, where training variables remain unchanged or change consistently. It may offer a more straightforward and more uncomplicated way of approaching training sessions but, as a result, may lead to flat progress. Hence, to clarify a more transparent approach to enhancing performance, this review article provides a more comprehensive theoretical comparison in depth between these methodologies, to try to delve into both conceptual frameworks' understanding, advantages, disadvantages, limitations, and practical applications. This article also aims to represent more literature on the background. While trying to uncover some shadowed parts of the theoretical framework, this article examines some of the impact of periodized strength training on neuromuscular adaptation, muscle hypertrophy and other structural changes, supported by a review of key research findings. Furthermore, the historical development of periodization theory is discussed, outlining the evolution from early practices to contemporary models and assessing its relevance in modern athletic training. The comparison highlights how each approach influences performance, adaptation, and recovery, emphasizing the need for further research to better understand and apply these training methodologies in diverse athletic contexts. The review concludes that while periodization offers structured progression and helps prevent performance plateaus, non-periodized training provides flexibility and may suit specific training scenarios where simplicity is preferred.
... Sessions opened with a short dynamic warm-up (15 seconds of joint mobility practice for each joint involved, and three 10-repetition sets at 5%, 10%, and 20% of 1RM) before the main training session (Borgenvik et al., 2012;McMillian et al., 2006). The experimental sessions encompassed six sets of bench press throws, until identifying a 10% loss in mean propulsive velocity (MPV) after two consecutive repetitions, with a five-minute rest interval between sets (Ahtiainen et al., 2005). Intensity varied each week (30% 1RM to 90% 1RM). ...
Velocity loss has been recognized as an effective fatigue index in resistance training. However, the physiological consequences of this fatigue should be described. Traditionally, researchers have debated the hormonal response to non-failure resistance training. Cortisol on salivary concentration was one of the hormones under study, which is linked to the inflammatory process from exercise. This study aimed to compare the acute salivary cortisol (Sal-C) response at different percentages of 1RM with fatigue standardized by a 10% velocity loss. An experimental, randomized, and counterbalanced activity was designed. Fifteen men took part in the study (they fasted for 12 hours before carrying out the test), performing 6 sets of bench press throw with different 1RM percentages (30% - 90% 1RM). Salivary Cortisol was collected before and after each test. Velocity loss was measured by a linear encoder. ANOVA and Effect Size were performed. Sal-C showed a significant decrease in all percentages and effect size was greater with low loads (1.61 high) than with high loads (0.95-1 moderate). Peak power was significantly higher between 40-70% of 1RM compared to other percentages (30-80% 1RM). The results of this research support the idea that velocity-based training sustains the dynamic equilibrium of organisms independently of intensity training. Moreover, untrained subjects could perform efficiently up to six sets at all percentages but with fewer repetitions at higher intensities, as this study shows that untrained subjects achieved 10% velocity loss under four repetitions.
... We initially screened 359 studies and identified 11 that potentially met inclusion criteria. After reviewing the full texts of these studies, 2 studies were excluded: one because neither set volume nor volume load was equated between conditions (30) and the other because the loading range was not equated in the initial set of the given exercise(s) (31). Figure 1 provides a flow chart of the search process. ...
We systematically searched the literature for studies with a randomized design that compared different inter-set rest interval durations for estimates of pre-/post-study changes in lean/muscle mass in healthy adults while controlling all other training variables. Bayesian meta-analyses on non-controlled effect sizes using hierarchical models of all 19 measurements (thigh: 10; arm: 6; whole body: 3) from 9 studies meeting inclusion criteria analyses showed substantial overlap of standardized mean differences across the different inter-set rest periods [binary: short: 0.48 (95%CrI: 0.19–0.81), longer: 0.56 (95%CrI: 0.24–0.86); Four categories: short: 0.47 (95%CrI: 0.19–0.80), intermediate: 0.65 (95%CrI: 0.18–1.1), long: 0.55 (95%CrI: 0.15–0.90), very long: 0.50 (95%CrI: 0.14–0.89)], with substantial heterogeneity in results. Univariate and multivariate pairwise meta-analyses of controlled binary (short vs. longer) effect sizes showed similar results for the arm and thigh with central estimates tending to favor longer rest periods [arm: 0.13 (95%CrI: −0.27 to 0.51); thigh: 0.17 (95%CrI: −0.13 to 0.43)]. In contrast, central estimates closer to zero but marginally favoring shorter rest periods were estimated for the whole body [whole body: −0.08 (95%CrI: −0.45 to 0.29)]. Subanalysis of set end-point data indicated that training to failure or stopping short of failure did not meaningfully influence the interaction between rest interval duration and muscle hypertrophy. In conclusion, results suggest a small hypertrophic benefit to employing inter-set rest interval durations >60 s, perhaps mediated by reductions in volume load. However, our analysis did not detect appreciable differences in hypertrophy when resting >90 s between sets, consistent with evidence that detrimental effects on volume load tend to plateau beyond this time-frame.
Systematic Review Registration: OSF, https://doi.org/10.17605/OSF.IO/YWEVC .
... Currently, much information is available regarding the optimal training load to be used during HIIT training programmes. However, intrasession rest intervals are a component that has not been extensively studied [33][34][35][36]. Sufficient rest intervals between exercises are crucial to counteract the negative impacts of fatigue and support muscle recovery. ...
The aim of this study was to evaluate the effect of 8 weeks of short and long rest running-based high-intensity training (HIIT) on body composition, isokinetic strength, and maximal oxygen uptake (VO 2max). Nineteen physically active men were recruited to voluntarily participate in the study. The participants were grouped using the closed-envelope randomized method as HIIT with a short rest (HIITS, n = 9; age: 19.60 ± 1.34 years) and HIIT with a long rest (HIITL, n = 10; age: 19.77 ± 0.97). Pre and post the 8-week running-based HIIT program, body mass index and body fat % were measured and all subjects performed isokinetic strength tests to determine their hamstring (H)/quadriceps (Q) peak torque ratio and the peak power and peak work for their H and Q muscles. The participants also underwent a graded exercise test to determine their VO 2max. Statistical analysis performed with One-Way Variance Analysis and Bonferroni correction post hoc tests. As a result of the study, there were no significant differences between the pre-and post-training isokinetic strength parameters for the H and Q of HIITL and HIITS at velocities of 60 and 240 • s −1. The VO 2max did not change for HIITS training but the VO 2max increased (p < 0.05) for HIITL training. In conclusion, that HIITL and HIITS programs for 8 weeks did not change the relative and absolute strength, force production and the VO 2max , but the VO 2max increased (p < 0.05) for HIITL training. Keywords Peak torque; Peak power; Peak work; VO 2max ; H/Q ratio
... Currently, much information is available regarding the optimal training load to be used during HIIT training programmes. However, intrasession rest intervals are a component that has not been extensively studied [33][34][35][36]. Sufficient rest intervals between exercises are crucial to counteract the negative impacts of fatigue and support muscle recovery. ...
The aim of this study was to evaluate the effect of 8 weeks of short and long rest running-based high-intensity training (HIIT) on body composition, isokinetic strength, and maximal oxygen uptake (VO2max). Nineteen physically active men were recruited to voluntarily participate in the study. The participants were grouped using the closed-envelope randomized method as HIIT with a short rest (HIITS, n = 9; age: 19.60 ± 1.34 years) and HIIT with a long rest (HIITL, n = 10; age: 19.77 ± 0.97). Pre and post the 8-week running-based HIIT program, body mass index and body fat % were measured and all subjects performed isokinetic strength tests to determine their hamstring (H)/quadriceps (Q) peak torque ratio and the peak power and peak work for their H and Q muscles. The participants also underwent a graded exercise test to determine their VO2max. Statistical analysis performed with One-Way Variance Analysis and Bonferroni correction post hoc tests. As a result of the study, there were no significant differences between the pre- and post-training isokinetic strength parameters for the H and Q of HIITL and HIITS at velocities of 60 and 240◦s−1. The VO2max did not change for HIITS training but the VO2max increased (p < 0.05) for HIITL training. In conclusion, that HIITL and HIITS programs for 8 weeks did not change the relative and absolute strength, force production and the VO2max, but the VO2max increased (p < 0.05) for HIITL training.
... Eight weeks strength training did not change basal TT, GH, and IGF-1 in the resting period. Indeed, evidence showed that long-term strength training did not alter hormone concentrations and no difference between trained and no-trained men [32,33]. Eight weeks of moderate-intensity resistance training of the upper body did not show a signi cant difference in testosterone concentrations between pre-pubertal and pubertal males [34]. ...
Purpose This study investigated how strength training affects adolescent athletes' hormonal, cytokine, and oxidative stress markers.
Methods The participants were split into two groups: Strength training (ST) (n=10) and control (C) (n=10). The strength training group participated in 8-week handball and strength training. The Control group followed their weekly handball training routine. The ST group participated in traditional strength training 3 days a week in addition to handball training for 8 weeks. We quantified hormone, oxidative stress markers and IL-6 in the subject’s blood samples.
Result Interestingly Insulin-like growth factor-1 concentration declined in the C group (p<0.05), while the ST serum concentrations did not change statistically (p>0.05). Insulin-like growth factor binding protein-3 (IGFBP3) and sex hormone binding globulin (SHBG) concentration of the ST decreased but did not in C. Serum-free testosterone (FT) levels increased in both groups, while total testosterone levels did not change. While total antioxidant status (TAS) and antioxidants stress index (ASI) did not change, total oxidant status (TOS) and oxidative stress index (OSI) reduced both groups (p<0.05). Serum interleukin-6 (IL-6) levels did not alter ST and C groups.
Conclusion While strength training did not affect serum concentrations of testosterone, GH, IGF-1, Cortisol, IL-6, and total antioxidant status, it caused a decrease in SHBG and IGFBP3. Serum FT levels increased in ST and C groups. Also, serum TOS levels declined ST and C; it is unclear whether strength training affects the increase in free testosterone or the decrease in TOS levels.
... Muscle strength and muscle hypertrophy adaptation in resistance training can be changed by the rest intervals between sets [1][2][3][4]; correction [5][6][7] is possible according to the goal of training. The rest interval (the length of time between sets) [7] and the exercise load (%-1RM), which are important factors influencing both the one-time response and long-term adaptations during resistance training [8], are modifiers of exercise intensity [8,9] that vary depending on the training objective. ...
The purpose of this study was a pilot study to determine the performance level and physiologic responses (heart rate and heart rate recovery (%)) of six different rest interval conditions during the performance of seven sets of a 65% 1RM bench press exercise. Eight healthy male university students who were 20 years of age and enrolled at University C were tested. The subjects’ bench press 1RM was measured before the experiment, and they performed bench press exercises with six different rest intervals (30 s, 1 min, 2 min, 3 min, 4 min, and 5 min), which were randomized and crossed over. The experimental measurements were performed once a week and repeated six times per rest interval condition (six intervals) to minimize the learning effect for the subjects. A two-way repeated measures ANOVA was used to verify the data, post-comparison (contrast: repeat) was used to establish statistical significance, and the following results were obtained. First, the level of exercise performance (reps) between sets across the six rest interval conditions showed significant differences (p < 0.000) and high effect sizes (ES ≥ 0.70) across the rest interval conditions. In addition, more reps (in terms of volume) were performed in the relatively longer rest interval conditions. The number of reps over the progression of the sets also showed a significant difference (p < 0.000) for the shorter rest interval condition, with a high effect size (ES ≥ 0.64). There was also an interaction effect (p < 0.000) between the rest interval condition and the set, with the number of repetitions at the beginning of the set decreasing significantly as the set progressed for the relatively short rest interval condition, with a high effect size (ES ≥ 0.60). Second, there was no statistically significant difference in after-exercise heart rate among the rest interval conditions between sets, but the longer rest interval conditions of 4 and 5 min showed a significant difference (p < 0.005) as the set progressed, with a high effect size (ES ≥ 0.41). In each of the six rest interval conditions, heart rate levels were similar in sets 1 and 2 but increased from set 3 to set 7. Immediately after each bout of exercise, the resting heart rate according to rest interval condition was statistically highest in the shorter rest intervals (30 s, 1 min), with a high effect size (p < 0.020) and a high ES ≥ 0.39. Heart rate was also higher in the 2, 3, 4, and 5-min rest intervals, and increased significantly (p < 0.000) as the sets progressed, with a high effect size. Third, heart rate recovery (%) according to the rest interval condition between sets was significantly higher in the longer rest interval conditions (1, 2, 3, 4, and 5 min) than in the 30 s rest interval condition (p < 0.039), with a high effect size (ES ≥ 0.37). In addition, heart rate recovery in all rest interval conditions significantly decreased as the sets progressed (p < 0.05), with a high effect size (ES ≥ 0.37). Taken together, there were significant differences in performance levels (reps), physiological responses, and recovery between rest interval conditions during the equal-intensity resistance exercises in this study. Furthermore, the performance levels between rest interval conditions during the 65% 1RM bench press exercise in this study suggest that rest intervals of 2–3 min may be effective for improving muscular endurance, while rest intervals of 4–5 min may be effective for improving muscle hypertrophy. This suggests that manipulating the rest intervals between sets during resistance training at the same intensity may lead to better training outcomes.
... Muscle strength and muscle hypertrophy adaptation by resistance training can be changed by rest interval between sets [1] [2][3] [4] and correction [5][6] [7] is possible according to the goal of training. The rest interval during resistance exercise means the time set between sets [8]) and is an important factor that affects one-time response and longterm adaptation [7] On the other hand, the intensity of exercise is defined as the percentage of 1RM used in a given exercise [8] [9]. ...
(1)Background:The purpose of the study was conducted to investigate the recovery of heart rate according to the performance level and rest interval conditions during 65%1RM bench press exercise;(2)Methods:The subjects of this study were eight healthy male college studentsin their 20 (years) attending University C. 1RM was measured before theexperiment, and the exercise sequence of six rest intervals (30sec, 1, 2, 3, 4,5min) was randomly selected and cross-distribution experiment. The experimental measurement was conducted a total of six times according to the rest interval condition (six conditions) once every 3 days to minimize the learning effect. The data was verified with repeated measures Two-way ANOVA and Contrast's repeated method was applied for post-comparison;(3)Results: First, the amount of exercise and the number of repetitions statistically substantially dropped (p<.001) as the number of sets rose, and a greater decline was shown when the rest periods got shorter. Second, the heart rate after exercise was increased significantly (p<.01) as the set progressed in the long rest interval conditions (4, 5min), and the heart rate after rest was increased statistically significantly (p<,05) as the set progressed in the short rest interval conditions (30sec, 1min). Third, the heart rate recovery rate (%) was able to perform more repetitions than in the short rest interval condition due to the relatively high physiological recovery of the neuromuscular and circulatory system under the long rest interval condition;(4)Conclusions: Therefore, according to the rest conditionduring the 65%1RM bench press exercise conducted in this study, the restinterval condition of 2~3min may be effective in improving muscular endurance,and the rest interval condition of 4~5min may be effective in improving muscular hypertrophy. As a result of this study, there was a significant difference in exercise performance (repetition) and physiological recovery depending on the rest interval condition according to the set progress during the same intensity resistance exercise. Through this, it is judged that it is possible to adjust the amount of exercise appropriate for the purpose of training by adjusting not only the intensity during resistance exercise but also the rest interval between sets.
... O presente estudo comparou diferentes intervalos de recuperação no treinamento de força no volume de treino, identificado pelo número de repetições na musculação em adultos saudáveis Os resultados da meta análise demonstraram efeito positivo nos grupos que utilizaram IR > de 2 minutos, pois isso gerou maior número de repetição e, consequentemente, maior volume de treino, que pode estimular respostas fisiológicas associadas a vias sinalizadoras de hipertrofia muscular, resultando no aumento de força e massa muscular. 23 ...
Introduction
The recovery interval (RI) between sets and exercises has received attention from strength training (ST) researchers, to understand the relationship of rest on performance maintenance, especially the total load in a training session. It is known that each individual responds in a specific way to the training stimulus. So, what would be the effect of the different recovery interval strategies on the strength performance?
Objective
Compare the different recovery intervals in strength training volume, considering the number of repetitions in healthy adults.
Methods
We conducted a systematic review and meta-analysis based on methodological criteria, comparing fixed and self-selected RI on training volume, identified by the number of repetitions performed in a weight training program. Three electronic databases (Pubmed, VHL Virtual Health Library, Ebsco Sportdiscus) were analyzed, combining the expressions “resistance training”, “resistance exercise”, “strength exercise”, “recovery interval”, “rest interval”, “interval auto suggested”, “auto range selected” with “AND” and “OR” combination.
Results
Pooled data from five studies showed a large significant effect in favor of the experimental group (>2 minutes) (MD: 1.24; 95%-CI [0.78; 1.71]; z: 5.25, Q:1.08; p < 0.01), since in the studies, recovery interval allowed a greater training volume.
Conclusion
Longer RI seems be better, for maintaining total training volume, although there is no consensus for different training objectives against the self-selected RI. Thus, we imagine that this strategy may be important in the organizing a bodybuilding exercise program. Level of Evidence I; Systematic Review and Meta Analysis.
Keywords:
Resistance Training; Rest; Health Strategies
... Intensity (weight) should be adjusted and based on the number of repetitions a person can perform, which gives us an idea of what intensity they are training at. Relative strength, for example, is best trained between one and five repetitions, and this gives us a specific intensity percentage at which a person is training if they can do less than five repetitions [47,48,[61][62][63]. If the intensity is set too low for performing the required number of repetitions, the results are not entirely valid. ...
The physical improvements from strength and resistance training have been known for decades, but the cognitive benefits of this type of activity are not as well-known. The aim of this review article is to provide a summary of studies presenting the effects of strength and resistance training on BDNF in healthy young adults. A systematic search of various electronic databases (PubMed, Web of Science, Science Direct and Google Scholar) was conducted in September 2022. Studies that examined associations between strength training and BDNF in healthy young adults aged 18–30 years were included. The final sample included 10 studies published between 2009 and 2020. The results of this literature review are inconclusive. Based on the results of the 10 studies, there is no clear answer as to whether strength training has positive effects on BDNF in healthy young adults.
... Some methodological differences can justify these distinct results. Firstly, a 2-minute interval was adopted for the short interval protocol during Ahtiainen et al. (3). Secondly, both groups were submitted to a matched VL condition. ...
International Journal of Exercise Science 15(4): 910-933, 2022. The regular practice of resistance training (RT) has been shown to induce relevant increases in both muscle strength and size. In order to maximize these adaptations, the proper manipulation of RT variables is warranted. In this sense, the aim of the present study was to review the available literature that has examined the application of the acute training variables and their influence on strength and morphological adaptations of healthy young adults. The information presented in this study may represent a relevant approach to proper training design. Therefore, strength and conditioning coaches may acquire a fundamental understanding of RT-variables and the relevance of their practical application within exercise prescription.
... All subjects were submitted to a testing protocol following the guidelines of APTA -American Physical Therapy Association [1,13,15,22] and soccer-specific studies using isokinetic machines [3,11,19]. The same physiotherapist, with 10 years of experience, performed all tests. ...
Study aim : To compare knee moment profiles of professional soccer players from different playing positions before and after an interseason period.
Material and methods : Retrospective study of 467 healthy, professional elite Brazilian soccer players before and after an official championship interseason period during 10-years. Main outcome measures were isokinetic peak moment from knee extensors and flexors from concentric and eccentric contractions. A Two-way ANOVA analysis was used to compare each playing position before and after interseason period.
Results : It was found no statistical difference in Ext.CPT (from p = 0.11 to p = 0.97), Ext.EPT (from p = 0.07 to p = 0.85), Flx. CPT (from p = 0.14 to p = 0.90) or Flx.EPT (from p = 0.10 to p = 0.91) between End-Season and Pre-Season evaluations for all playing positions (from Goalkeepers, Defenders, Backsiders, Midfielders and Forwards).
Conclusions : Isokinetic peak moment did not have significant differences after an interseason period of 4 to 6 weeks, allowing trainers and coaches to focus their pre-season period on other performance concerns than strengthening.
... Some methodological differences can justify these distinct results. Firstly, a 2-minute interval was adopted for the short interval protocol during Ahtiainen et al. (3). Secondly, both groups were submitted to a matched VL condition. ...
International Journal of Exercise Science 15(4): X-Y, 2022. The regular practice of resistance training (RT) has been shown to induce relevant increases in both muscle strength and size. In order to maximize these adaptations, the proper manipulation of RT variables is warranted. In this sense, the aim of the present study was to review the available literature that has examined the application of the acute training variables and their influence on strength and morphological adaptations of healthy young adults. The information presented in this study may represent a relevant approach to proper training design. Therefore, strength and conditioning coaches may acquire a fundamental understanding of RT-variables and the relevance of their practical application within exercise prescription.
... 30 s rest interval decreased total training volume by more than 24% in the 10-repetition group in comparison to the group that had 5 min rest interval. Ahtiainen et al. (2005) addressed the question of short and long rest intervals on strength, muscle size and hormonal adaptations of the quadriceps muscle in trained men. Thirteen recreationally strength-trained individuals (28.7 ± 6.2 years) participated in the crossover-design study. ...
Skeletal muscle is one of the most important tissues of the human body. It comprises up to 40% of the body mass and is crucial to survival. Hence, the maintenance of skeletal muscle mass and strength is pivotal. It is well-established that resistance exercise provides a potent anabolic stimulus to increase muscle mass and strength in men and women of all ages. Resistance exercise consists of mechano-biological descriptors, such as load, muscle action, number of repetitions, repetition duration, number of sets, rest interval between sets, frequency, volitional muscular failure, and range of motion, which can be manipulated. Herein, we discuss the evidence-based contribution of these mechano-biological descriptors to muscle mass and strength.
... As concern rest periods, it was observed that exercise with long versus short rest periods (2-5min vs 30-40s) induce a greater strength increase [7]. In contrast, according to other studies, low intensity, high volume and moderate rest periods (2-3min) training program have been demonstrated to induce an increase of hypertrophy [8,9]. ...
Background: The modulation of rest intervals in resistance training could induce
different muscular tissue and hormonal response. The aim of the present pilot study
was to the long-term adaptations induced by short rest intervals in high-load resistance
training.
Methods: Ten healthy untrained subjects (age 25.6±4.7 years) underwent a 3-weekly
2-month high-load (>90% of RM) resistance-training program with short rest intervals
between stets (<90 sec) and low recovery time between exercises (120 sec). Every
exercise session was structured in order to train the entire body (bench press, pulley, leg
press, curl with dumbbell, french press, hummer curl, hummer curl with relaxation and
pull ups) such as to move close to a ’classical’ training tab. Anthropometric parameters,
strength and hormonal responses were taken in all the subjects before and after the
training protocol.
Results: Training increased arm (P<0.05), thigh (P<0.05) and chest (P<0.01)
circumferences, while decreased waist circumference (P=n.s) with respect to baseline.
Strength on RM was increased on bench press (P<0.05), pulley (P<0.05) and leg press
(P<0.01) exercises. Blood analyses showed a decrease of IGF1 (P=n.s) and cortisol
(P<0.05), while testosterone (P=n.s), DHT (P<0.01) and GH (P<0.001) were increased. In
addition, we observed an increase of TEST/CORT ratio (P<0.05).
Conclusion: The results of the present study showed that a single training program
with short rest intervals associated to high-load strength exercises could induce an
increase in both muscular mass and strength
... O treinamento resistido é conhecido como uma ferramenta efetiva para estimular a hipertrofia das fibras musculares e aprimorar os níveis de força (AHTIAINEN et al., 2005;RATAMESS, 2005). A manipulação das variáveis agudas de treinamento (seleção e ordem dos exercícios, intensidade, volume, número de séries e repetições, frequência e período de intervalo entre séries) pode resultar em diferentes níveis de estresse mecânico, metabólico e endócrino, resultando em adaptações fisiológicas e morfológicas específicas do tecido muscular esquelético (SPIERING et al., 2008;RATAMESS, 2012). ...
O objetivo desta pesquisa foi investigar a influência do exercício resistido máximo e submáximo com diferentes períodos de intervalo de recuperação entre séries sobre as concentrações de testosterona total e cortisol em jovens treinados. Seis jovens treinados (22±3,3 anos) realizaram 4 sessões de treinamento resistido com diferentes intensidades e períodos de intervalo de recuperação entre séries (PI). As sessões apresentavam as seguintes características: (sub60): 3x10 rep., 70% de 10RM, PI 60seg.; (max60): 3x8-12 rep., 95% de 10RM, PI 60seg.; (sub180): 3x10 rep., 70% de 10RM, PI 180seg.; (max180): 3x8-12 rep., 95% de 10RM, PI 180seg. Os exercícios utilizados foram: supino reto, pressão de pernas, puxada pela frente na polia alta e cadeira extensora. Dez minutos antes e imediatamente após as sessões de treinamento, amostras de sangue foram coletadas para determinação das concentrações de testosterona total e cortisol. Foi constatado aumento na concentração de testosterona total na sub60 (17±10%; p=0,013), sub180 (20±12%; p=0,005) e max60 (20±14%; p=0,014). Para o cortisol, foi observado redução apenas na sub180 (-38±10%; p=0,001). Aumentos na relação testosterona/cortisol foram encontrados na sub60 (p=0,044) e sub180 (p=0,003). Os valores da testosterona total foram mais elevados na sub60 em relação a sub180 (p=0,039) e max180 (p=0,048) no momento POS. A sessão de treinamento resistido envolvendo exercícios submáximos e período de intervalo de recuperação entre séries longo (sub180) foi efetiva em elevar a testosterona total e reduzir o cortisol em jovens treinados, resultando em uma alta relação testosterona/cortisol e favorecendo um melhor ambiente anabólico.
... In the somewhat earlier research conducted by Ahtiainen et al., it was shown that the length of regeneration between series was important in the case of hormonal or neuro-muscular response, or the long-term effects of adaptation in the muscle tissue among the studied men practicing recreational sports [51]. Comparing the muscle mass of bodybuilders training with moderate weights, thus, taking short intervals between series that produce a large amount of metabolic stress, and powerlifters who train with very intense loads, resting for a longer time, the conclusion arises that both these sports groups are characterised by impressive muscles. ...
Research aim: The objective of research was to present the influence of strength training on selected systems of human organs on the basis of available literature on the subject. Methodology: A review was conducted of international literature based on analysis of selected articles available at Google Scholar, PubMed, SciCentral. Results: Changes in the human body as a result of both strength exercises and training were demonstrated based on analysis of the available literature. Summary: The results and the rate of benefiting from the practive of strength disciplines largely depend on gender, genetic characteristics, age, training history, health status, diet, lifestyle, current physical activity and stress levels.
... This study demonstrates that the phenomenon responsible for rFE is reproducible during consecutive PS-ISO contractions, similar to standard resistance-training protocols [60]. The potential benefits of a contraction mode that incorporates an eccentric stimulus, resulting in an enhanced isometric steady-state force at a reduced metabolic cost [53], are intriguing. ...
Residual force enhancement (rFE) is observed when isometric force following an active stretch is elevated compared to an isometric contraction at corresponding muscle lengths. Acute rFE has been confirmed in vivo in upper and lower limb muscles. However, it is uncertain whether rFE persists using multiple, consecutive contractions as per a training simulation. Using the knee flexors, 10 recreationally active participants (seven males, three females; age 31.00 years ± 8.43 years) performed baseline isometric contractions at 150° knee flexion (180° representing terminal knee extension) of 50% maximal voluntary activation of semitendinosus. Participants performed post-stretch isometric (PS-ISO) contractions (three sets of 10 repetitions) starting at 90° knee extension with a joint rotation of 60° at 60°·s−1 at 50% maximal voluntary activation of semitendinosus. Baseline isometric torque and muscle activation were compared to PS-ISO torque and muscle activation across all 30 repetitions. Significant rFE was noted in all repetitions (37.8–77.74%), with no difference in torque between repetitions or sets. There was no difference in activation of semitendinosus or biceps femoris long-head between baseline and PS-ISO contractions in all repetitions (ST; baseline ISO = 0.095–1.000 ± 0.036–0.039 Mv, PS-ISO = 0.094–0.098 ± 0.033–0.038 and BFlh; baseline ISO = 0.068–0.075 ± 0.031–0.038 Mv). This is the first investigation to observe rFE during multiple, consecutive submaximal PS-ISO contractions. PS-ISO contractions have the potential to be used as a training stimulus.
... The experimental evidence on the influence of short (≤1 min) and long (≥3 min) interset intervals during strength training is mixed. Some studies showed an advantage of long interset intervals for muscle hypertrophy (74,125), whereas others found either better result with short interset intervals (126) or no significant difference (127,128). However, the workout volume in the two training programs was not matched in all of these studies (74,128), which likely influenced the conclusion. ...
Training with low-load exercise performed under blood-flow restriction can augment muscle hypertrophy and maximal strength to a similar extent as the classical high-load strength training method. However, the blood-flow restriction method elicits only minor neural adaptations. In an attempt to maximize training-related gains, we propose using other protocols that combine high voluntary activation, mechanical tension and metabolic stress.
... Previous studies have shown that the acute and chronic effects of RT are influenced by the interset rest intervals (Ahtiainen et al., 2005;Kraemer et al., 1987;Senna et al., 2009). The American College of Sports Medicine recommend short interset rest intervals (e.g., 30-90 seconds) during hypertrophy-oriented RT sessions, whereas longer interset rest intervals (e.g., 3-5 minutes) are recommended during strength-oriented and poweroriented RT sessions (Ratamess et al., 2009). ...
This study aimed to compare the effect of three interset rest intervals (1, 3, and 5 minutes) on (I) mean velocity during a resistance training session conducted in a Smith machine with the squat and bench press exercises, and (II) the pre- and post-exercise force-velocity relationship. Fifteen male university students completed three sessions (i.e., Rest 1ʹ, Rest 3ʹ, and Rest 5ʹ) consisting of three sets of five repetitions against the 10RM load during the squat and bench press exercises. The force-velocity relationship (maximal values of force [F 0], velocity [v0], and power [Pmax]) was evaluated at the beginning and at the end of each session with the countermovement jump and bench press throw exercises. During training, mean velocity was slower in sets 2 and 3 of the Rest 1ʹ protocol compared to Rest 3ʹ and Rest 5ʹ, but no significant differences were present between Rest 3ʹ and Rest 5ʹ. After training, there was a significant decrease in F 0 (p = 0.017) and Pmax (p = 0.010), but not in v0 (p = 0.259). These results support the Rest 3ʹ as the most time-efficient protocol, among those analysed, for the maintenance of high mean velocities during training sessions not leading to failure.
... Testosterone. Resistance exercise protocols of high volume (3-6 sets; 8-12 reps), moderate load (60-85% 1RM), and short rest intervals (30-90 seconds), which activate large muscle groups, elicit the greatest acute elevations in testosterone (2,8,12,17,39,68,75,96). However, there are no guidelines regarding the tempo of movement in these recommendations. ...
Wilk, M, Tufano, JJ, and Zajac, A. The influence of movement tempo on acute neuromuscular, hormonal, and mechanical responses to resistance exercise—a mini review. J Strength Cond Res XX(X): 000–000, 2020—Resistance training studies mainly analyze variables such as the type and order of exercise, intensity, number of sets, number of repetitions, and duration and frequency of rest periods. However, one variable that is often overlooked in resistance training research, as well as in practice, is premeditated movement tempo, which can influence a myriad of mechanical and physiological factors associated with training and adaptation. Specifically, this article provides an overview of the available scientific literature and describes how slower tempos negatively affect the 1-repetition maximum, the possible load to be used, and the number of repetitions performed with a given load, while also increasing the total time under tension, which can mediate acute cardiovascular and hormonal responses. As a result, coaches should consider testing maximal strength and the maximal number of repetitions that can be performed with each movement tempo that is to be used during training. Otherwise, programming resistance training using various movement tempos is more of a trial-and-error approach, rather than being evidence or practice based. Furthermore, practical applications are provided to show how movement tempo can be adjusted for a variety of case study–type scenarios.
The aim of the study was to investigate how 8-week strength training affects adolescent athletes’ basal hormone concentrations, sex hormone binding globulin (SHBG), insulin-like growth factor binding protein-3 (IGFBP-3), cytokine, and oxidative stress markers.
Twenty adolescent handball players participated in this study. The participants were randomly divided into the strength training group (ST, n = 10) and the control group (C, n = 10). ST participates in strength training 3 sessions a week for 8 weeks and C participates only in handball training. We quantified serum basal hormone concentration, SHBG, IGFBP3, oxidative stress markers, and IL-6 in each subject’s blood samples before and after 8 weeks of strength training.
Interestingly, while insulin-like growth factor-1 (IGF-1) concentration declined in group C (p < 0.05), it did not in ST (p > 0.05). Furthermore, the basal concentration of growth hormone (GH), total testosterone (T), cortisol (Cor), total antioxidant status (TAS), and serum-free androgen index (FAI) basal concentration did not change in ST and C. Basal IGFBP-3 and SHBG concentrations decreased only in ST (p < 0.05), but not in C (p > 0.05). Serum-free testosterone (FT) levels increased in ST and C (p > 0.05). Total oxidant status (TOS) and oxidative stress index (OSI) reduced ST and C (p < 0.05). Serum interleukin-6 (IL-6) levels did not alter groups ST and C.
Strength training did not affect basal serum concentrations of T, GH, IGF-1, COR, IL-6, and TAS, but it caused a decrease in SHBG and IGFBP3 concentrations in ST. Increased basal FT concentration and improved serum TOS may not depend on strength training.
Longer rest intervals between resistance exercise (RE) sets may promote greater muscle hypertrophy and strength gains over time by facilitating completion of greater training volume and intensity. However, little is known about the acute neuromuscular responses to RE sets incorporating longer vs. shorter rest intervals. Using a within-subjects, cross-over design, 8 healthy, young participants completed two separate acute bouts of 4 sets of 8 x 3-s maximal isometric contractions using either a 2-min (REST-2) or 5-min (REST-5) rest interval between sets. Peak torque (PT) and EMG were measured pre and 5-min post-exercise. PT and mean torque (MT), EMG, mean and median frequencies were measured during each set, while blood lactate (BL), heart rate (HR) and RPE were measured following each set. PT and MT were lower (p<0.05) in sets 3 and 4, and sets 2-4 in REST-2 compared to REST-5, respectively. EMG and BL were lower and higher, respectively, in REST-2 vs. REST-5. There was no main effect of condition on HR or RPE. Pre-to-post exercise reductions in PT (-17±9% vs. -4±7%) and EMG (-29±14% vs. -10±7%) were greater (p<0.001) in REST-2 vs. REST-5. Total exercise volume was less in REST-2 vs. REST-5 (9,748±2296 N.m vs. 11,212±2513 N.m, p<0.001). These results suggest that incorporating 5-min between-set rest intervals into a resistance exercise session facilitates improved neuromuscular function, increased exercise volume and less metabolic stress compared to 2-min rest intervals. Thus, 5-min rest intervals may be more efficacious for promoting muscle hypertrophy and strength gains in a chronic resistance training programme.
Background and Purpose: Variable resistance training (VRT) is a type of resistance training that helps to improve muscle strength and function through extra resistance such as elastic bands and chains. The comparison of the effect of constant resistance training (CRT) versus VRT on hormonal response has not been fully studied. So, this study investigated the acute and chronic effects of VRT versus CRT on the salivary concentration of testosterone, growth hormone, and cortisol in trained men. Materials and Methods: 30 young resistance-trained men were recruited for this study and were randomly assigned to three groups including VRT, CRT, and control. Both training groups performed an exercise protocol with an intensity of 65 to 85% of 1RM for 10 weeks and 3 sets (three sessions per week). The training included the main upper and lower extremity exercises and the rest period between the sets and exercises was 1 and 2-3 minutes respectively. In addition, the VRT group used 7.5 kg chains as an external variable resistance. Oral saliva samples were collected before and after the first session (acute response) and the last session (chronic response) and then analyzed by ELISA method. Inter-group changes were analyzed by repeated measures analysis of variance and Bonferroni's post hoc test. The significance level was also considered equal to P ≤ 0.05. Results: a significant group×time interaction was observed only for the acute response of salivary testoster-one (P = 0.003). So, a significant increase was observed in the salivary of testosterone in the VRT compared to CRT (P = 0.001) and control (P = 0.003), although no significant differences were observed for cortisol (P=0.64), growth hormone (P = 0.52) and testosterone to growth hormone (P = 0.49). Also, no significant group×time interaction was observed for testosterone (P = 0.377), cortisol (P=0.57), testosterone to cortisol ratio (P = 0.91), and growth hormone (P = 0.200) in chronic response (P > 0.05). Conclusion: The results showed that a session of VRT caused a significant increase in testosterone hormone immediately after exercise, but 10 weeks of VRT or CRT had no significant effect on the levels of testos-terone, cortisol, and growth. It seems that if VRT is performed with higher intensity or volume, additional hormonal responses will occur as a result of exercise, and therefore the effectiveness of the exercise will promote.
Background: Quadriceps angle is the angle produced between the quadriceps muscle and the patellar tendon, which is also known as Q angle. It is also regarded as a key component for the correct knee posture and movement. Q angle is frequently employed as a diagnostic indicator for knee-related issues such as anterior knee pain, degenerative knee disorders, osteoarthritis etc. It has a great clinical and biomechanics significance and this angle gives useful information about alignment of lower limb. Present study shows association of Q angle with gender, various anthropometric measurements and Quadriceps muscle strength. Methods: Total 150 healthy young individuals (20 male and 130 female) between the age of 18 to 30 years from the different constituent institutes of Sumandeep Vidyapeeth University were included in the study. Q angle was measured in degrees by using universal goniometer on both sides. Anthropometric measurements - Height, weight. Body mass index, Waist and Hip circumference, Intercondylar distance between femur and Quadriceps muscle strength were measured. Results: In this study, the correlation between Q angle and Anthropometric measurements were analyzed. The mean Q angle on right side was 18.87 and on left side was 18.87. Bilaterally, no significant differences were found in Q angle. The angle of right and left side was significantly correlated with weight, height, BMI, intercondylar distance and quadriceps muscle strength. However, these angles are not correlated with WHR. Conclusion: This study supported positive correlation of weight and BMI with Q angle; negative correlation of height, intercondylar distance of femur and quadriceps muscle strength with Q angle. Although, no significant correlation was found between Q angle and WHR.
The aim of the research was to determine the effects of exercise programs on lower limbs’ explosive strength in junior tennis players. For collecting of appropriate scientific researches from 2010 till 2021 the following keywords were used: tennis, eplosive strength, training and exercise program, motor ability- in three electronic databases (Google Scholar, KobSon, SCI index). Based on the keywords, the existing scientific researches have gone through three levels of selection in order to enter the final analysis. These analyzed researches are presented through five groups of parameters: authors of the research, sample description (sex, age and number), experimental treatment (description, frequency), measuring instruments and results. Only 10 researches have met the criteria, and the analysis shown that the exercise programs lasted from 6 to 8 weeks, with weekly training frequency between two and three times of 30 minutes, that is, as an addition to the training. Exercise programs that have been used for the development of lower limbs’ explosive strength in tennis players were of plyometric type, with and without equipment. The tests, by which the assessment of the lower limb’ explosive strength was determined, were: CMJ, CMJ (bilateral/unilateral), SJ, DJ and OLH. The results of the applied exercise programs have shown, in all of the analyzed researches, statistically significant progress (p<0.05). A lower-limb explosive strength represents a very significant segment within the basic motor skills of tennis players in the junior category due to the latent period of development period, but also to the pretensions of the increasing dynamism of the tennis game. In accordance with this, the research can help trainers to use the information for planning the development of the explosive strength of their tennis players, and for athletes to advance and manifest the maximum potential of this part of this basic motor space.
Purpose
The study aimed to compare the effects of exercise therapy plus manual therapy (ET plus MT) and exercise therapy (ET) alone on muscle activity, muscle onset latency timing and shoulder pain and disability index-Hindi (SPADI-H) score in athletes with shoulder impingement syndrome (SIS).
Materials and method
Overhead male athletes diagnosed with SIS were randomly allocated into ET plus MT group(n=40) and ET group(n=40). Muscle activity, muscle onset latency timings and SPADI-H score were assessed. Both the groups performed 8 weeks of intervention and were evaluated at baseline, 4th and 8th weeks.
Result
ET plus MT group was more effective in increasing muscle activity, optimising latency timings and decreasing SPADI score when compared to ET group alone(p<0.05).After treatment muscle activity and SPADI-H improved in both groups (p<0.05).
Conclusion
ET plus MT was superior for improving muscle activity, muscle onset latency timing and SPADI score compared to ET alone.
Background/aim
The purpose of this study was to compare the isokinetic peak torque profiles from the quadriceps and hamstrings muscles during concentric and eccentric contractions in elite Brazilian soccer players across different field positions and age categories. Our hypothesis was that soccer players from different field positions are subjected to different ageing-related effects on their isokinetic peak torque.
Methods
This is a retrospective study based on professional elite-level soccer players between the years 2009 and 2019. It included 570 adult males who played for at least 5 years on first or second Brazilian divisions. Playing positions were divided as: goalkeepers, defenders, sidebacks, midfielders and forwards. Age categories were also divided as: G1 (17–20 years old), G2 (21–24 years old), G3 (25–28 years old), G4 (29–32 years old) and G5 (33 years old or more).
Results
The results indicate a moderate effect of age (F(4545)=8.197; p<0.001; η ² =0.057) and a small effect of playing position (F(4545)=2.993; p<0.05; η ² =0.021) on torque of concentric extensors; mainly from midfielders and goalkeepers with 29 years or more.
Conclusions
Soccer players from different field positions are subjected to different ageing related effects on their muscular performance during their career special attention should be given to these players to avoid reduction in physical performance.
En la actualidad, el fútbol es uno de los deportes con mayor campo de investigación científica. En los últimos tiempos, el entrenamiento de la fuerza ha adquirido un papel fundamental en la planificación y
programación del entrenamiento en fútbol, ya que, influye de forma positiva en la mejora de las demás cualidades y, por tanto, en un mayor rendimiento del deportista. Sin embargo, aún existe mucha controversia sobre el desarrollo de trabajos de fuerza en jugadores jóvenes de fútbol y su posible interferen cia con otras cualidades físicas y/o antropométricas. El objetivo de esta tesis doctoral, fue comparar los efectos que producen dos tratamientos de fuerza diferentes, sobre la capacidad de salto, el consumo máximo de oxígeno y la composición corporal, en jugadores jóvenes de fútbol durante una temporada, atendiendo a la categoría (cadete/juvenil) y la demarcación específica (portero, defensa central, lateral, centrocampista, extremo y delantero). Los tratamientos de fuerza fueron: 1. Grupo de fuerza con au tocargas (GAUT) y 2. Grupo de fuerza con sobrecargas (GSOB). Después de 37 semanas, con un total de 74 sesiones de entrenamiento,se produjeron mejoras significativas sobre la capacidad de salto (17.54 % GAUT ; 16.54 % GSOB ) y sobre el consumo máximo de oxígeno (7.58 % GAUT; 6.69 % GSOB). Además, se produjeron descensos del % graso (13.94 %), aumentos significativos desde el 0.5 al 1.84 % en la variable altura (cm) y aumentos en la masa muscular (Kg) (8.30 % GAUT; 4.81 % GSOB), en ambas categorías.
Podemos concluir que las diferentes metodologías de entrenamiento de fuerza utilizadas, hicieron mejorar de manera significativa las variables de rendimiento estudiadas. Así pues, podemos indicar que tanto el tratamiento de fuerza con autocargas como el de sobrecargas, son métodos de entrenamiento válidos y óptimos para producir cambios a niveles neuromusculares, cardiorrespiratorios y antropométricos. Por último, se recomienda tanto a los entrenadores y/o preparadores físicos, qu e implementar un programa de entrenamiento de fuerza durante la temporada en jugadores jóvenes de fútbol, es efectivo para mejorar el rendimiento de sus jugadores.
Objective: The squat exercise is one of the most exhaustive one in which different resistance training methods can elicit various changes in the concentration of many metabolites circulating in the blood. Therefore, the aim of this study is to assess the differences between slow (5/0/3/0) and conventional (2/0/2/0) barbell squat movement tempo to concentric failure on acute metabolites and hormonal responses.
Materials and methods: Ten experienced powerlifters (24.3 ± 3.2 y; 77.9 ± 7.2 kg; 141 ± 17.5 kg Squat 1RM) who compete at the national and international level performed five sets of the barbell squat exercise (SQ) to failure at load 80% 1RM with two different tempo of movement: a 2/0/2/0 medium tempo (MED) and a 5/0/3/0 slow tempo (SLO) randomly one week apart. Venous blood samples (10ml) were collected from the antecubital vein, to determine acute pre and post-exercise values of testosterone (T), growth hormone (GH), insulin-like growth factor I (IGF-1), cortisol (C), creatine kinase (CK) and lactate acid (LA).
Results: The SLO protocol resulted in higher time under tension (p<0.01) and lower number of performed repetition (p<0.01) than MED protocol. Both exercise protocols test showed high increase of T, C, GH, IGF-1, CK and LA between pre and post exercise (p<0.01). Performing 5 sets of SLO squats resulted in higher post exercise increase of LA (p < 0.03) and CK (p < 0.02) than MED protocol. There were no other significant differences in analysed endocrine variables. Therefore, the SLO exercise tempo elicit higher lactate and muscle damage, but not the acute hormonal response.
Conclusion: This study demonstrated that in terms of endocrine response, the optimal moderate exercise tempo result in high endocrine response, which is not dramatically increased by longer time under tension resulting from slow exercise execution. On the other hand, slow speed resulting in longer time under tension cause more muscle damage and lactate production, which may play a large role in stimulating muscle growth and tissue regeneration.
PMID: 33315342
Background/Aim
Different authors have tried to correlate the peak isokinetic torque values with the incidence of soccer match injuries. However, due to the wide variety of assessment testing protocols, such an inference becomes difficult. This study aimed to verify the capacity of an isokinetic test to establish injury risk reference values for hamstring strain injuries.
Methods
A retrospective cohort study based on isokinetic data and clinical records from the last 10 years was conducted in 582 Brazilian elite-professional soccer players, who were subjected to the same isokinetic test protocol, machine, and tester. A Multivariate Logistic Regression Analysis for Complex Data Sampling was used to generate injury risk statistical indexes.
Results
Multivariate regression analysis of both legs provided important data to identify the cut-off values of Concentric Peak Torque (181.82 Newton/*metres), Concentric Work (236.23 watts) and Concentric Power (130.11 joules).
Conclusions
The injury risk indexes indicate that an increase of just one Newton unit in CPT (Concentric Peak Torque) and CJ (Concentric Power) above those cut-off values, can reduce the risk of future injuries by 2% and 2.7%, respectively.
Aim: Aging is associated with the reduction of interleukin-15 levels (IL-15), muscles atrophy and consequently loss of muscular strength. The purpose of present study was to investigate the effect of 8-weeks resistance training with Thera-band on the serum levels of IL-15, balance and muscle strength in elderly women.
Method: In a quasi-experimental study, 18 elderly women (age: 73.66 ±4.79 years; BMI: 25.6±3.25) randomly were divided into following groups: experimental (n=10) and control (n=8). Resistance training program included 40 min workouts with Thera-Band for 8 weeks and 3 times per week. Forty eight hours before and after the training protocol balance, hand grip and trunk strength were measured using dynamometer, and blood samples were taken in fasted state. Serum levels of IL-15 were assessed by enzyme-linked immunosorbent assay (ELISA).
Results: The results showed that the serum levels of IL-15 (P= 0.029), balance (P= 0.003) right hand strength (P= 0.010), left hand strength (P=0.001) and low extremely strength (P=0.001) increased significantly in resistance training with Thera- band group in compared to control group.
Conclusion: Based on these findings it could be concluded that Thera-band training may improve the balance in elderly women and there is a relationship between the changes of muscular strength and IL-15 levels.
Effects of strength training (ST) for 21 wk were examined in 10 older women (64 ± 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12–12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. After the 21-wk ST, maximal force increased by 37% ( P < 0.001) and 1-RM by 29% ( P < 0.001), accompanied by an increase ( P < 0.01) in rate of force development. The integrated electromyograms of the vastus muscles increased ( P < 0.05). The CSA of the total QF increased ( P < 0.05) throughout the length of the femur by 5–9%. The increases were significant ( P< 0.05) at 7/15–12/15 Lf for VL and at 3/15–8/15 Lf for VM, at 5/15–9/15 for VI and at 9/15 ( P < 0.05) for RF. The fiber areas of type I ( P < 0.05), IIa ( P < 0.001), and IIb ( P < 0.001) increased by 22–36%. No changes occurred during ST in serum basal concentrations of the hormones examined, but the level of testosterone correlated with the changes in the CSA of the QF ( r = 0.64, P < 0.05). An acute increase of GH ( P < 0.05), remaining elevated up to 30 min ( P < 0.05) postloading, was observed only at posttraining. Both neural adaptations and the capacity of skeletal muscle to undergo training-induced hypertrophy even in older women explain the strength gains. The increases in the CSA of the QF occurred throughout its length but differed selectively between the individual muscles. The serum concentrations of hormones remained unaltered, but a low level of testosterone may be a limiting factor in training-induced muscle hypertrophy. The magnitude and time duration of the acute GH response may be important physiological indicators of anabolic adaptations during strength training even in older women.
Thirty-five healthy men were matched and randomly assigned to one of four training groups that performed high-intensity strength and endurance training (C; n = 9), upper body only high-intensity strength and endurance training (UC; n = 9), high-intensity endurance training (E; n = 8), or high-intensity strength training (ST; n = 9). The C and ST groups significantly increased one-repetition maximum strength for all exercises (P < 0.05). Only the C, UC, and E groups demonstrated significant increases in treadmill maximal oxygen consumption. The ST group showed significant increases in power output. Hormonal responses to treadmill exercise demonstrated a differential response to the different training programs, indicating that the underlying physiological milieu differed with the training program. Significant changes in muscle fiber areas were as follows: types I, IIa, and IIc increased in the ST group; types I and IIc decreased in the E group; type IIa increased in the C group; and there were no changes in the UC group. Significant shifts in percentage from type IIb to type IIa were observed in all training groups, with the greatest shift in the groups in which resistance trained the thigh musculature. This investigation indicates that the combination of strength and endurance training results in an attenuation of the performance improvements and physiological adaptations typical of single-mode training.
To examine endogenous anabolic hormonal responses to two different types of heavy resistance exercise protocols (HREPs), eight male and eight female subjects performed two randomly assigned protocols (i.e. P-1 and P-2) on separate days. Each protocol consisted of eight identically ordered exercises carefully designed to control for load, rest period length, and total work (J) effects. P-1 utilized a 5 RM load, 3-min rest periods and had lower total work than P-2. P-2 utilized a 10 RM load, 1-min rest periods and had a higher total work than P-1. Whole blood lactate and serum glucose, human growth hormone (hGH), testosterone (T), and somatomedin-C [SM-C] (i.e. insulin-like growth factor 1, IGF-1) were determined pre-exercise, mid-exercise (i.e. after 4 of the 8 exercises), and at 0, 5, 15, 30, and 60 min post-exercise. Males demonstrated significant (p less than 0.05) increases above rest in serum T values, and all serum concentrations were greater than corresponding female values. Growth hormone increases in both males and females following the P-2 HREP were significantly greater at all time points than corresponding P-1 values. Females exhibited significantly higher pre-exercise hGH levels compared to males. The P-1 exercise protocol did not result in any hGH increases in females. SM-C demonstrated random significant increases above rest in both males and females in response to both HREPs.(ABSTRACT TRUNCATED AT 250 WORDS)
To examine endogenous anabolic hormone and growth factor responses to various heavy resistance exercise protocols (HREPs), nine male subjects performed each of six randomly assigned HREPs, which consisted of identically ordered exercises carefully designed to control for load [5 vs. 10 repetitions maximum (RM)], rest period length (1 vs. 3 min), and total work effects. Serum human growth hormone (hGH), testosterone (T), somatomedin-C (SM-C), glucose, and whole blood lactate (HLa) concentrations were determined preexercise, midexercise (i.e., after 4 of 8 exercises), and at 0, 5, 15, 30, 60, 90, and 120 min postexercise. All HREPs produced significant (P less than 0.05) temporal increases in serum T concentrations, although the magnitude and time point of occurrence above resting values varied across HREPs. No differences were observed for T when integrated areas under the curve (AUCs) were compared. Although not all HREPs produced increases in serum hGH, the highest responses were observed consequent to the H10/1 exercise protocol (high total work, 1 min rest, 10-RM load) for both temporal and time integrated (AUC) responses. The pattern of SM-C increases varied among HREPs and did not consistently follow hGH changes. Whereas temporal changes were observed, no integrated time (AUC) differences between exercise protocols occurred. These data indicate that the release patterns (temporal or time integrated) observed are complex functions of the type of HREPs utilized and the physiological mechanisms involved with determining peripheral circulatory concentrations (e.g., clearance rates, transport, receptor binding). All HREPs may not affect muscle and connective tissue growth in the same manner because of possible differences in hormonal and growth factor release.
An 8-wk progressive resistance training program for the lower extremity was performed twice a week to investigate the time course for skeletal muscle adaptations in men and women. Maximal dynamic strength was tested biweekly. Muscle biopsies were extracted at the beginning and every 2 wk of the study from resistance-trained and from nontrained (control) subjects. The muscle samples were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain content. In addition, fasting blood samples were measured for resting serum levels of testosterone, cortisol, and growth hormone. With the exception of the leg press for women (after 2 wk of training) and leg extension for men (after 6 wk of training), absolute and relative maximal dynamic strength was significantly increased after 4 wk of training for all three exercises (squat, leg press, and leg extension) in both sexes. Resistance training also caused a significant decrease in the percentage of type IIb fibers after 2 wk in women and 4 wk in men, an increase in the resting levels of serum testosterone after 4 wk in men, and a decrease in cortisol after 6 wk in men. No significant changes occurred over time for any of the other measured parameters for either sex. These data suggest that skeletal muscle adaptations that may contribute to strength gains of the lower extremity are similar for men and women during the early phase of resistance training and, with the exception of changes in the fast fiber type composition, that they occur gradually.
Nine eumenorrheic women (age 24.11 +/- 4.28 yr) performed each of six randomly assigned heavy-resistance protocols (HREPs) on separate days during the early follicular phase of the menstrual cycle. The HREPs consisted of two series [series 1 (strength, S) and series 2 (hypertrophy, H)] of three protocols, each using identically ordered exercises controlled for load [5 vs. 10 repetitions maximum (RM)], rest period length (1 vs. 3 min), and total work (J) within each three-protocol series. Blood measures were determined pre-, mid- (after 4 of 8 exercises), and postexercise (0, 5, 15, 30, 60, 90, 120 min and 24 and 48 h). In series 1, a significant (P < 0.05) reduction in growth hormone (GH) was observed at 90 min postexercise for all three protocols. In series 2, the 10-RM protocol with 1-min rest periods (H10/1) produced significant increases above rest in GH concentrations at 0, 5, and 15 min postexercise, and the H10/1 and H5/1 protocols demonstrated significant reductions at 90 and 120 min postexercise. Cortisol demonstrated significant increases in response to the S10/3 protocol at 0 min, to the H10/1 protocol at midexercise and at 0 and 5 min postexercise, and to the H5/1 protocol at 5 and 15 min postexercise. No significant changes were observed in total insulin-like growth factor I, total testosterone, urea, or creatinine for any of the HREPs. Significant elevations in whole blood lactate and ammonia along with significant reductions in blood glucose were observed. Hormonal and metabolic blood variables measured in the early follicular phase of the menstrual cycle varied in response to different HREPs. The most dramatic increases above resting concentrations were observed with the H10/1 protocol, indicating that the more glycolytic HREPs may stimulate greater GH and cortisol increases.
This paper reviews the factors (exercise intensity, carbohydrate availability, exercise type, energy balance, gender, exercise training, age, and timing of nutrient intake or subsequent exercise sessions) thought to influence protein need. Although there remains some debate, recent evidence suggests that dietary protein need increases with rigorous physical exercise. Those involved in strength training might need to consume as much as 1.6 to 1.7 g protein x kg(-1) x day(-1) (approximately twice the current RDA) while those undergoing endurance training might need about 1.2 to 1.6 g x kg(-1) x day(-1) (approximately 1.5 times the current RDA). Future longitudinal studies are needed to confirm these recommendations and asses whether these protein intakes can enhance exercise performance. Despite the frequently expressed concern about adverse effects of high protein intake, there is no evidence that protein intakes in the range suggested will have adverse effects in healthy individuals.
Effects of strength training (ST) for 21 wk were examined in 10 older women (64 +/- 3 yr). Electromyogram, maximal isometric force, one-repetition maximum strength, and rate of force development of the leg extensors, muscle cross-sectional area (CSA) of the quadriceps femoris (QF) and of vastus lateralis (VL), medialis (VM), intermedius (VI) and rectus femoris (RF) throughout the lengths of 3/12--12/15 (Lf) of the femur, muscle fiber proportion and areas of types I, IIa, and IIb of the VL were evaluated. Serum hormone concentrations of testosterone, growth hormone (GH), cortisol, and IGF-I were analyzed for the resting, preexercise, and postexercise conditions. After the 21-wk ST, maximal force increased by 37% (P < 0.001) and 1-RM by 29% (P < 0.001), accompanied by an increase (P < 0.01) in rate of force development. The integrated electromyograms of the vastus muscles increased (P < 0.05). The CSA of the total QF increased (P < 0.05) throughout the length of the femur by 5--9%. The increases were significant (P < 0.05) at 7/15--12/15 Lf for VL and at 3/15--8/15 Lf for VM, at 5/15--9/15 for VI and at 9/15 (P < 0.05) for RF. The fiber areas of type I (P < 0.05), IIa (P < 0.001), and IIb (P < 0.001) increased by 22--36%. No changes occurred during ST in serum basal concentrations of the hormones examined, but the level of testosterone correlated with the changes in the CSA of the QF (r = 0.64, P < 0.05). An acute increase of GH (P < 0.05), remaining elevated up to 30 min (P < 0.05) postloading, was observed only at posttraining. Both neural adaptations and the capacity of skeletal muscle to undergo training-induced hypertrophy even in older women explain the strength gains. The increases in the CSA of the QF occurred throughout its length but differed selectively between the individual muscles. The serum concentrations of hormones remained unaltered, but a low level of testosterone may be a limiting factor in training-induced muscle hypertrophy. The magnitude and time duration of the acute GH response may be important physiological indicators of anabolic adaptations during strength training even in older women.
Seventy-three healthy, male subjects randomly divided into 3 groups participated in a study to determine the effects of 2 high-calorie nutritional supplements on body composition, body segment circumferences, and muscular strength following a resistance-training (RT) program.
In addition to their normal diets group 1 (CHO/PRO; n=26) consumed a 8.4 Mj x day(-1) (2010 kcal) high calorie, high protein supplement containing 356 g carbohydrate and 106 g protein. Group 2 (CHO; n=25) consumed a carbohydrate supplement that was isocaloric with CHO/PRO. Group 3 (CTRL; n=22) received no supplement and served as a control. All subjects were placed on a 4-day x week(-1) RT program for 8 weeks.
Dietary analysis revealed no significant differences in total energy consumption or nutrients at any time in the non-supplemented diets of the 3 groups. Significant (p= or <0.05) increases in body mass (BM) and fat-free mass (FFM) were observed in CHO/PRO and CHO compared to CTRL. Mean (+/- SD) increases in BM were 3.1+/-3.1 kg and 3.1+/-2.2 kg, respectively. Fat-free mass significantly (p= or <0.05) increased 2.9+/-3.4 kg in CHO/PRO and 3.4+/-2.5 kg in CHO. Muscular strength, as measured by a one-repetition maximum in the bench press, leg press, and lat-pull down increased significantly (p= or <0.05) in all groups. No significant differences in strength measures were observed among groups following training.
Results indicate that high-calorie supplements are effective in increasing BM and FFM when combined with RT. However, once individual protein requirements are met, energy content of the diet has the largest effect on body composition.
Hormonal and neuromuscular adaptations to strength training were studied in eight male strength athletes (SA) and eight non-strength athletes (NA). The experimental design comprised a 21-week strength-training period. Basal hormonal concentrations of serum total testosterone (T), free testosterone (FT) and cortisol (C) and maximal isometric strength, right leg 1 repetition maximum (RM) of the leg extensors were measured at weeks 0, 7, 14 and 21. Muscle cross-sectional area (CSA) of the quadriceps femoris was measured by magnetic resonance imaging (MRI) at weeks 0 and 21. In addition, the acute heavy resistance exercises (AHRE) (bilateral leg extension, five sets of ten RM, with a 2-min rest between sets) including blood samples for the determination of serum T, FT, C, and GH concentrations were assessed before and after the 21-week training. Significant increases of 20.9% in maximal force and of 5.6% in muscle CSA in NA during the 21-week strength training period were greater than those of 3.9% and -1.8% in SA, respectively. There were no significant changes in serum basal hormone concentrations during the 21-week experiment. AHRE led to significant acute decreases in isometric force and acute increases in serum hormones both at weeks 0 and 21. Basal T concentrations (mean of 0, 7, 14 and 21 weeks) and changes in isometric force after the 21-week period correlated with each other (r=0.84, P<0.01) in SA. The individual changes in the acute T responses between weeks 0 and 21 and the changes in muscle CSA during the 21-week training correlated with each other (r=0.76, P<0.05) in NA. The correlations between T and the changes in isometric strength and in muscle CSA suggest that both serum basal testosterone concentrations and training-induced changes in acute testosterone responses may be important factors for strength development and muscle hypertrophy.
Acute hormonal and neuromuscular responses and recovery three days after the exercises were examined during the maximum repetitions (MR) and forced repetitions (FR) resistance exercise protocols in 16 male athletes. MR included 4 sets of leg presses, 2 sets of squats and 2 sets of knee extensions (with 12 RM) with a 2-min recovery between the sets and 4 min between the exercises. In FR the initial load was chosen to be higher than in MR so that the subject could not lift 12 repetitions per set by himself. After each set to failure the subject was assisted to perform the remaining repetitions to complete the 12 repetitions per set. Thus the exercise intensity was greater in FR than in MR. Both loading protocols led to the great acute increases (p < 0.05 - 0.001) in serum testosterone, free testosterone, cortisol and GH concentrations. However, the responses in cortisol (p < 0.05) and GH (p < 0.01) were larger in FR than in MR. The decrease of 56.5 % (p < 0.001) in maximal isometric force in FR was greater (p < 0.001) than that of 38.3 % in MR (p < 0.001) and force remained lower (p < 0.01) during the recovery in FR compared to MR. The larger decrease in isometric strength in FR than in MR was also associated with the decreased maximal voluntary EMG of the loaded muscles. The data indicate that the forced repetition exercise system induced greater acute hormonal and neuromuscular responses than a traditional maximum repetition exercise system and therefore it may be used to manipulate acute resistance exercise variables in athletes.
An introduction to terms and concepts associated with resistance training is given. Sports associated with this training, such as power lifting and body building, are described. The merits of free weights versus resistance machines are discussed. The article recommends a training program for beginners. (Author/JL)
The purpose of this study was to compare serum growth hormone (GH), testosterone (T), cortisol (C), and whole blood lactate (L) responses to single set (1S) versus multiple set (3S) heavy-resistance exercise protocols. Eight recreationally weight-trained men completed two identical resistance exercise workouts (1S vs. 3S). Blood was obtained preexercise (PRE), immediately postexercise (OP), and 5 min (5P), 15 min (15P), 30 min (30P) and 60 min (60P) postexercise and was analyzed for GH, T, C, and L levels. For 1S and 3S, GH, L, and T significantly increased from PRE to OP and remained significantly elevated to 60P, except for 1S. For GH, T, and L, 3S showed significantly greater increases compared to 1S. For C, 3S and 1S were increased significantly from resting at OP, 5P, and 15P; 3S increased compared to 1S at 5P, 15P and 30P. Higher volumes of total work produce significantly greater increases in circulating anabolic hormones during the recovery phase following exercise.
Leucine kinetic and nitrogen balance (NBAL) methods were used to determine the dietary protein requirements of strength athletes (SA) compared with sedentary subjects (S). Individual subjects were randomly assigned to one of three protein intakes: low protein (LP) = 0.86 g protein.kg-1.day-1, moderate protein (MP) = 1.40 g protein.kg-1.day-1, or high protein (HP) = 2.40 g protein.kg-1.day-1 for 13 days for each dietary treatment. NBAL was measured and whole body protein synthesis (WBPS) and leucine oxidation were determined from L-[1-13C]leucine turnover. NBAL data were used to determine that the protein intake for zero NBAL for S was 0.69 g.kg-1.day-1 and for SA was 1.41 g.kg-1.day-1. A suggested recommended intake for S was 0.89 g.kg-1.day-1 and for SA was 1.76 g.kg-1.day-1. For SA, the LP diet did not provide adequate protein and resulted in an accommodated state (decreased WBPS vs. MP and HP), and the MP diet resulted in a state of adaptation [increase in WBPS (vs. LP) and no change in leucine oxidation (vs. LP)]. The HP diet did not result in increased WBPS compared with the MP diet, but leucine oxidation did increase significantly, indicating a nutrient overload. For S the LP diet provided adequate protein, and increasing protein intake did not increase WBPS. On the HP diet leucine oxidation increased for S. These results indicated that the MP and HP diets were nutrient overloads for S. There were no effects of varying protein intake on indexes of lean body mass (creatinine excretion, body density) for either group. In summary, protein requirements for athletes performing strength training are greater than for sedentary individuals and are above current Canadian and US recommended daily protein intake requirements for young healthy males.
A follow-up study of 1 year was performed on 11 male elite weight lifters. Several parameters including training volume, weight lifting performance, and serum hormone concentrations were measured during seven test occasions. In addition, the same measurements were repeated three times during a 6-week period preceding the primary competition, which took place about 5 months after beginning of the follow-up. The primary findings were observed during the 6-week period from which the first 2 weeks of stressful training was associated with significant decreases (P less than 0.01-0.001) in serum testosterone concentration, in testosterone/cortisol and in testosterone/SHBG ratios, and with a significant (P less than 0.001) increase in serum LH concentration. The individual changes during the stressful training in serum testosterone/SHBG ratio were related (r = .63; P less than 0.05) to the individual changes in the weight lifting result in the clean and jerk lift. During the following "normal" 2-week and reduced 2-week training periods, the concentration of serum testosterone remained unaltered, but serum cortisol and serum LH decreased significantly (P less than 0.05-0.01). During these periods, the serum testosterone/SHBG ratio increased (P less than 0.01). The individual changes during this preparatory 4-week training before the primary competition in serum testosterone/SHBG ratio and the individual changes in the weight lifting result in the clean and jerk lift correlated significantly with each other (r = .68; P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
Acute neuromuscular and endocrine adaptations to weight-lifting were investigated during two successive high intensity training sessions in the same day. Both the morning (I) (from 9.00 to 11.00 hours) and the afternoon (II) (from 15.00 hours to 17.00 hours) training sessions resulted in decreases in maximal isometric strength (p less than 0.01 and less than 0.05), shifts (worsening) in the force-time curve in the absolute scale (p less than 0.05 and ns.) and in decreases in the maximal integrated EMG (p less than 0.01 and less than 0.05) of the selected leg extensor muscles. Increases in serum total (p less than 0.05) and free testosterone (p less than 0.01) and in cortisol (p less than 0.01) concentrations were found during training session II. These were followed by decreases (p less than 0.001 and p less than 0.01 and ns.) in the levels of these hormones one hour after the termination of the session. The responses during the morning training session were different with regard to the decreases in serum total testosterone (p less than 0.05), free testosterone (ns.) and cortisol (p less than 0.05). Only slight changes were observed in the levels of luteinizing hormone and sex hormone-binding globulin during the training sessions. Increases (p less than 0.01) took place in somatotropin during both training sessions. The present findings suggest that high intensity strengthening exercises may result in acute adaptive responses in both the neuromuscular and endocrine systems. The diurnal variations may, however, partly mask the exercise-induced acute endocrinological adaptations in the morning.(ABSTRACT TRUNCATED AT 250 WORDS)
Heavy-resistance exercise utilizing very short rest periods is commonly used by body builders to prepare for competition. The purpose of this study was to compare the acute responses of this type of heavy-resistance exercise protocol in competitive body builders (BB) and power lifters (PL). Nine male BB and eight PL were matched for age, size and experience. A ten-station heavy-resistance exercise protocol was used. Each subject performed three sets of 10 repetition maximum (RM) with 10-s rest between sets and alternated 30-s and 60-s rest periods between exercises. No differences were observed in total work between the groups, but BB used a significantly (P less than 0.05) higher percentage of their 1 RM in the bench press and leg press exercises. Heart rate, ratings of perceived exertion (RPE), and lactate levels were obtained during the exercise protocol; significant (P less than 0.05) increases were observed above rest for these variables. RPE was significantly correlated with lactate levels (r = 0.84). Plasma epinephrine, norepinephrine, dopamine, cortisol, and lactate levels significantly increased from pre- to 5 min post-exercise. Mean plasma volumes were reduced -16.6 (+/- 3.64)% and -20.6 (+/- 8.32)% following the exercise protocol for BB and PL, respectively. Significant (P less than 0.05) decreases in eosinophil counts were observed following exercise. No significant differences were observed between BB and PL for any of the physiologic responses measured. PL exhibited a higher incidence (100%) of clinical symptoms of dizziness and nausea compared to BB (11.1%).(ABSTRACT TRUNCATED AT 250 WORDS)
The central changes associated with a period of strength training have been investigated in a group of 32 young healthy volunteers. Subjects participated in one of three 12 week training programmes, which required different degrees of skill and coordination. Study 1 consisted of unilateral isometric training of the quadriceps with the contralateral leg acting as a control, the apparatus providing firm back support and a lap strap. In Study 2 training consisted of unilateral concentric leg-extension with back support and hand-grips. In Study 3 subjects performed bilateral leg-extension with no back support. Measurements of maximum voluntary isometric strength were made at 2-3 week intervals and a continual record was kept of the weights lifted in Studies 2 and 3. The largest increase in isometric force was seen for the trained leg in Study 1 (approximately 40%). There was no significant change in strength in the contralateral untrained leg. In Studies 2 and 3 there was a large increase in training weights (about 200%) associated with smaller increase in isometric force (15-20%). It is concluded that a large part of the improvement in the ability to lift weights was due to an increased ability to coordinate other muscle groups involved in the movement such as those used to stabilise the body. The importance of these findings for athletic training and rehabilitation is discussed.
Eleven male subjects (20-32 years) accustomed to strength training went through progressive, high-load strength training for 24 weeks with intensities ranging variably between 70 and 120% during each month. This training was also followed by a 12-week detraining period. An increase of 26.8% (P less than 0.001) in maximal isometric strength took place during the training. The increase in strength correlated (P less than 0.05) with significant (P less than 0.05-0.01) increases in the neural activation (IEMG) of the leg extensor muscles during the most intensive training months. During the lower-intensity training, maximum IEMG decreased (P less than 0.05). Enlargements of muscle-fibre areas, especially of fast-twitch type (P less than 0.001), took place during the first 12 weeks of training. No hypertrophic changes were noted during the latter half of training. After initial improvements (P less than 0.05) no changes or even slight worsening were noted in selected force-time parameters during later strength training. During detraining a great (P less than 0.01) decrease in maximal strength was correlated (P less than 0.05) with the decrease (P less than 0.05) in the maximum IEMGs of the leg extensors. This period resulted also in decreases (P less than 0.05) of the mean muscle-fibre areas of both fibre types. It was concluded that improvement in strength may be accounted for by neural factors during the course of very intensive strength training. Selective training-induced hypertrophy also contributed to strength development but muscle hypertrophy may have some limitations during long-lasting strength training, especially in highly trained subjects.
1. Skinfold thickness and body density were measured on 105 young adult men and women and 86 adolescent boys and girls.
2. The correlation coefficients between the skinfold thicknesses, either single or multiple, and density were in the region of −0.80.
3. Regression equations were calculated to predict body fat from skinfolds with an error of about ±3.5%.
4. A table gives the percentage of the body-weight as fat from the measurement of skin-fold thickness.
The purpose of this paper is to present a hypothetical model for strength training and to present supporting data. The model is an attempt to conform to the concepts of training 'periodization' and specificity of training. The model consists of four phases: (1) Hypertrophy, high volume-low intensity, (2) Basic Strength, moderate volume-high intensity, (3) Strength-Power, low volume-very high intensity (special subphases include maintenance and peaking), (4) Active Rest, very low volume-very low intensity. A review of the literature indicates that three sets of six repetitions maximum, 3 days/week is the generally recommended method of attaining maximal strength increases. However, a short term comparison (6 weeks) showed the model to be superior in producing gains in the squat (1 RM), squat/kg body weight and power as measured using the vertical jump and Lewis formula. Additionally two observations of the practical use of the model with high caliber athletes are presented. Six Olympic niveau weightlifters were observed at three competitions about 3 months apart. The 3 lifters training according to the concepts of the model showed greater improvement compared to the three using traditional methods. The second observation used a high school American-style football team. The players using the strength training model produced greater gains (bench press, squat and power) than the players using 3x6 RM over a 12 week period. The data gathered suggest that the model for strength training presented produces superior strength-power gains when compared to traditional methods.
To examine effects of fatiguing heavy resistance loading on voluntary neural activation and force production ten male and nine female athletes loaded their leg extensor muscles by performing 10 sets in the squat-life exercise by performing 10 repetitions in each set with the maximal load possible (about 70% of 1 RM in each set; 10*10*70%). A recovery time of 3 minutes was allowed between each set. Maximal voluntary neural activation (integrated EMG), maximal isometric force, force-time and relaxation time curves of the leg extensor muscles were measured before, during and immediately after the loading session. The maximal force was recorded also after rest for 1 hour, 2 hours, 1 day and 2 days. The relative decrease of 47.1 +/- 10.5% (p < 0.001) recorded in maximal force in males was significantly (p < 0.01) greater than the decrease of 29.4 +/- 13.8% (p < 0.001) recorded for females. Significant decreases were also observed in the maximal IEMGs of the exercised muscles both in males (p < 0.01) and females (p < 0.05). The exercise loading led also to great shifts in the shape of the force-time curve, on average, in males by 49.3 +/- 11.5% (p < 0.001) but less (p < 0.05) in females by 32.4 +/- 16.2% (p < 0.001). In males significant (p < 0.01) decreases took place also in the voluntary rapid neural activation of the exercised muscles in the IEMG-time curve. The time of force relaxation lengthened (p < 0.05) in both groups. The mean blood lactate concentration increased in males up to 15.0 +/- 4.0 mmol x 1(-1) (p < 0.001) and less (p < 0.001) in females up to 6.0 +/- 1.8 mmol x 1(-1) (p < 0.001). Maximal force recovered during the first two hours and the first day of rest less in males than in females. The present findings suggest that strenuous heavy resistance loading may result in remarkable acute fatigue in the neuromuscular system observable not only in the contractile characteristics of the exercised muscles as the decrease in force production but also by the decrease in the voluntary neural activation of the exercised muscles. In males neuromuscular fatigue may be greater and recovery from fatigue slower than in females.
In a previous study, a 6-hour local infusion of growth hormone (GH) into the brachial artery of normal subjects stimulated net muscle protein anabolism by augmenting skeletal muscle protein synthesis. In the present study, we examined whether systemically infused GH affects forearm and whole-body protein metabolism. Normal volunteers aged 18 to 24 years (n = 8) were given an 8-hour systemic infusion of 3H-phenylalanine and 14C-leucine. Between 90 and 120 minutes of tracer infusion, basal samples for determination of forearm and whole-body amino acid kinetics were taken. GH was then infused at 0.06 micrograms/kg/min, increasing GH concentration from 2.4 +/- 0.3 to 32 +/- 3 ng/mL. Systemic insulin-like growth factor 1 (IGF-1) level increased from 224 +/- 20 to 262 +/- 21 ng/mL (basal v 6-hour, P < .01). By 6 hours, GH suppressed forearm phenylalanine and leucine net release (each P < .05) by increasing 3H-phenylalanine (66%, P < .05) and 14C-leucine (13%, P < .05) extraction or disposal (Rd). Whole-body leucine rate of appearance ([Ra] an index of whole-body proteolysis) and nonoxidative leucine Rd (whole-body protein synthesis) did not change over the course of the GH infusion, whereas oxidative leucine Rd decreased (20%, P < .03). Acute stimulation of muscle but not whole-body protein synthesis by systemically infused GH suggests that muscle protein is acutely and specifically regulated by GH.
To examine endogenous hormonal responses to heavy-resistance exercise, ten male strength athletes performed two fatiguing but different types of sessions on separate days. In session A the loads for the leg extensor muscles in the squat-lift exercise were maximal so that the subjects performed 20 sets at 1 repetition maximum (RM) (20 x 1 RM x 100%), whereas during session B the loads were submaximal (70%) but the subjects performed each of the 10 sets until the RM (i.e., 10 repetitions/set or 10 x 10 x 70%). The recovery time between the sets was always 3 min. A decrease of 10.3 +/- 4.7% (P < 0.001) occurred in the squat-lift in 1 RM during session A, whereas session B led to a decrease of 24.6 +/- 18.9% (P < 0.001) in 10 RM. Increases in the concentrations of serum total and free testosterone (P < 0.05 and 0.05, respectively), cortisol (P < 0.001), and growth hormone (GH, P < 0.001) were observed during session B, whereas the corresponding changes during session A were statistically insignificant except for the relatively slight increase (P < 0.01) in serum GH level. The significant (P < 0.001) increase in blood lactate concentration during the two sessions correlated significantly (P < 0.01) with the increase in serum GH concentration. The morning values of serum testosterone and free testosterone were significantly (P < 0.05-0.001) lowered on the 1st and 2nd rest days after the sessions.(ABSTRACT TRUNCATED AT 250 WORDS)
To examine neuromuscular fatigue and recovery ten male and nine female athletes performed a strenuous heavy resistance exercise protocol. The subjects strained their leg extensor muscles with the same maximal relative intensity by performing one maximal squat-lift with a load of 100% of 1 RM (one repetition maximum) 20 times (20 x 1 x 100%). Maximal voluntary neural activation (integrated EMG), maximal bilateral isometric force, force-time and relaxation-time curves of the leg extensor muscles were measured before and immediately after the exercise session as well as after resting for 1 hour, 2 hours, 1 day and 2 days. The session resulted in considerable gradual decreases in maximal force in the males by 24.1 +/- 14.4% (p < 0.001) and in the females by 20.5 +/- 11.8% (p < 0.01) as recorded immediately after the session. Significant (p < 0.05-0.01) decreases also took place in the males in the maximal IEMGs of the exercised muscles, while the corresponding decreases in the females were minor. The force-time curve shifted greatly to the right both in the males (p < 0.001) and in the females (p < 0.01) but the average change of 27.8 +/- 13.8% in the males was greater (p < 0.05) than that of 18.7 +/- 8.3% recorded for the females. The time of force relaxation lengthened (p < 0.05) in both groups. Maximal force recovered during the first hour of rest was more (p < 0.05) in the females than in the males but thereafter the recovery took place gradually in both groups to the same degree.(ABSTRACT TRUNCATED AT 250 WORDS)
Acute hormone responses of growth hormone (GH), total and free testosterone (TT and FT) and cortisol (C) to heavy resistance isometric exercise were examined in ten young men [YM 26.5 (SD 4.8) years] and ten old men [OM 70.0 (SD 3.7) years]. Loading conditions of the same relative intensity were created for the lower and upper extremity actions separately as well as for both of them together lower extremity exercise (LE; knee extension), upper extremity exercise (UE; bench press extension), and lower and upper extremity exercise (LUE) performed simultaneously in a seated position. Single voluntary maximal isometric actions lasting for 5 s were performed repeatedly for ten repetitions (with a recovery of 5 s) for a total of four sets. The recovery time between the sets was 1 min. Each exercise led to large acute decreases in maximal isometric force in both YM (P < 0.001) and OM (P < 0.001) ranging from 41% to 26% with no significant differences between the groups. Serum GH concentrations increased in both YM (P < 0.05-0.01) and OM (P < 0.05) but the postexercise value in YM during LE was greater (P < 0.05) than for OM. The TT increased (P < 0.01-0.001) in YM in all three exercises, while in OM the increase occurred only during LE (P < 0.01). The exercises led to increases in FT in YM (P < 0.05 for LE and LUE), while in OM the increase occurred only during LUE (P < 0.05). The pre and postexercise FT were greater in YM (P < 0.001) than in OM. No significant changes occurred in C either in YM or in OM. The blood lactate concentrations increased during the exercises in both YM (P < 0.001) and OM (P < 0.05-0.001) but the postexercise values during LE and LUE in YM were greater (P < 0.05) than in OM. The present data would indicate that the responses of GH, TT and FT to heavy resistance isometric exercise are lowered with increasing age. The reduced acute hormone response together with the lowered basal values in FT in the older men compared to the young men may indicate decreased anabolic effects on muscles and may explain in part the loss of muscle mass and strength associated with aging.
Testosterone administration (T) increases lean body mass and muscle protein synthesis. We investigated the effects of short-term T on leg muscle protein kinetics and transport of selected amino acids by use of a model based on arteriovenous sampling and muscle biopsy. Fractional synthesis (FSR) and breakdown (FBR) rates of skeletal muscle protein were also directly calculated. Seven healthy men were studied before and 5 days after intramuscular injection of 200 mg of testosterone enanthate. Protein synthesis increased twofold after injection (P < 0.05), whereas protein breakdown was unchanged. FSR and FBR calculations were in accordance, because FSR increased twofold (P < 0.05) without a concomitant change in FBR. Net balance between synthesis and breakdown became more positive with both methodologies (P < 0.05) and was not different from zero. T injection increased arteriovenous essential and nonessential nitrogen balance across the leg (P < 0.05) in the fasted state, without increasing amino acid transport. Thus T administration leads to an increased net protein synthesis and reutilization of intracellular amino acids in skeletal muscle.
We examined the effect of resistance training on the response of mixed muscle protein fractional synthesis (FSR) and breakdown rates (FBR) by use of primed constant infusions of [2H5]phenylalanine and [15N]phenylalanine, respectively, to an isolated bout of pleiometric resistance exercise. Trained subjects, who were performing regular resistance exercise (trained, T; n = 6), were compared with sedentary, untrained controls (untrained, UT; n = 6). The exercise test consisted of 10 sets (8 repetitions per set) of single-leg knee flexion (i.e., pleiometric muscle contraction during lowering) at 120% of the subjects' predetermined single-leg 1 repetition maximum. Subjects exercised one leg while their contralateral leg acted as a nonexercised (resting) control. Exercise resulted in an increase, above resting, in mixed muscle FSR in both groups (UT: rest, 0.036 +/- 0.002; exercise, 0.0802 +/- 0.01; T: rest, 0.045 +/- 0.004; exercise, 0.067 +/- 0.01; all values in %/h; P < 0.01). In addition, exercise resulted in an increase in mixed muscle FBR of 37 +/- 5% (rest, 0.076 +/- 0.005; exercise, 0.105 +/- 0.01; all values in %/h; P < 0.01) in the UT group but did not significantly affect FBR in the T group. The resulting muscle net balance (FSR - FBR) was negative throughout the protocol (P < 0.05) but was increased in the exercised leg in both groups (P < 0.05). We conclude that pleiometric muscle contractions induce an increase in mixed muscle protein synthetic rate within 4 h of completion of an exercise bout but that resistance training attenuates this increase. A single bout of pleiometric muscle contractions also increased the FBR of mixed muscle protein in UT but not in T subjects.
To examine the adaptations of the endocrine system to heavy-resistance training in younger vs. older men, two groups of men (30 and 62 yr old) participated in a 10-wk periodized strength-power training program. Blood was obtained before, immediately after, and 5, 15, and 30 min after exercise at rest before and after training and at rest at -3, 0, 6, and 10 wk for analysis of total testosterone, free testosterone, cortisol, growth hormone, lactate, and ACTH analysis. Resting values for insulin-like growth factor (IGF)-I and IGF-binding protein-3 were determined before and after training. A heavy-resistance exercise test was used to evaluate the exercise-induced responses (4 sets of 10-repetition maximum squats with 90 s of rest between sets). Squat strength and thigh muscle cross-sectional area increased for both groups. The younger group demonstrated higher total and free testosterone and IGF-I than the older men, training-induced increases in free testosterone at rest and with exercise, and increases in resting IGF-binding protein-3. With training the older group demonstrated a significant increase in total testosterone in response to exercise stress along with significant decreases in resting cortisol. These data indicate that older men do respond with an enhanced hormonal profile in the early phase of a resistance training program, but the response is different from that of younger men.
Effects of 6 months of heavy resistance training combined with explosive exercises on both basal concentrations and acute responses of total and free testosterone, growth hormone (GH), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), cortisol and sex hormone-binding globulin (SHBG), as well as voluntary neural activation and maximal strength of knee extensors were examined in 10 middle-aged men (M40; 42 +/- 2 years), 11 middle-aged women (W40; 39 +/- 3 years), 11 elderly men (M70; 72 +/- 3 years), and in 10 elderly women (W70; 67 +/- 3 years). The maximal integrated electromyographic (iEMG) and 1 repetition maximum (RM) knee-extension values remained unaltered in all groups during a 1-month control period with no strength training. During the 6-month training the 1RM values increased in M40 by 27 +/- 9% (p < .001), in M70 by 16 +/- 6% (p < .001), in W40 by 28 +/- 11% (p < .001), and in W70 by 24 +/- 10% (p < .001). The iEMGs of the vastus lateralis and medialis muscles increased(p < .05-.001) in M40, M70, W40, and W70. No systematic changes occurred during the experimental period in the mean concentrations of serum total and free testosterone, DHEA, DHEAS, GH, cortisol, or SHBG. However, the mean levels of individual serum free testosterone in W70 and serum testosterone in the total group of women correlated with the individual changes recorded in strength during the training (r = .55,p <.05; and r = .43,p <.05). The single exercise session both before and after the training resulted in significant responses in serum total and free testosterone concentrations in both male groups (p <.05-.01), but not in the female groups, as well as in serum GH levels in all groups (p <.05-.01) except W70 (ns). In summary, the present strength training led to great increases in maximal strength not only in middle-aged but also in elderly men and women. The strength gains were accompanied by large increases in the maximal voluntary activation of the trained muscles. None of the groups showed systematic changes in the mean serum concentrations of hormones examined. However, a low level of testosterone, especially in older women, may be a limiting factor in strength development and testosterone could mediate interactions with the nervous system contributing to strength development. The physiological significance of the lack of acute responsiveness of serum GH to heavy resistance exercise in older women for their trainability during prolonged strength training requires further examination.
Exercise has a profound effect on muscle growth, which can occur only if muscle protein synthesis exceeds muscle protein breakdown; there must be a positive muscle protein balance. Resistance exercise improves muscle protein balance, but, in the absence of food intake, the balance remains negative (i.e., catabolic). The response of muscle protein metabolism to a resistance exercise bout lasts for 24-48 hours; thus, the interaction between protein metabolism and any meals consumed in this period will determine the impact of the diet on muscle hypertrophy. Amino acid availability is an important regulator of muscle protein metabolism. The interaction of postexercise metabolic processes and increased amino acid availability maximizes the stimulation of muscle protein synthesis and results in even greater muscle anabolism than when dietary amino acids are not present. Hormones, especially insulin and testosterone, have important roles as regulators of muscle protein synthesis and muscle hypertrophy. Following exercise, insulin has only a permissive role on muscle protein synthesis, but it appears to inhibit the increase in muscle protein breakdown. Ingestion of only small amounts of amino acids, combined with carbohydrates, can transiently increase muscle protein anabolism, but it has yet to be determined if these transient responses translate into an appreciable increase in muscle mass over a prolonged training period.
To describe the organization and implementation of nutrition policies, and examine intervention strategies for dietary change in three Scandinavian countries.
Descriptions of nutrition policies and dietary intervention strategies are based on published nutrition policy research and reports.
All countries studied have adopted formal nutrition policies. Norway issued its first white paper in 1976, the Finnish National Nutrition Council published an action plan in 1989, and the Swedish Government issued an official action plan in 1995. Norway has a centralized National Nutrition Council with a permanent administration whereas the responsibilities and administration are more spread out between several authorities and groups in Finland and Sweden. Amongst the dietary intervention strategies employed, a Norwegian nutrition campaign, symbol labelling of foods in Sweden, the community-based North Karelia Project in Finland, and mass catering in Finland and Sweden have been selected as potentially transferable.
Policy documents serve as guidelines for activities and assist in achieving dietary targets. A responsible administrative body with advice from a standing expert committee is valuable for implementation. Guidelines, recommendations or voluntary labelling standards can be incentives to product development and changes to food production. Regional demonstration projects may also encourage action and collaboration.
Growth hormone acutely stimulates skeletal muscle but not whole-body protein synthesis in humans
- D A J And E
- Barrett
FRYBURG, D.A., AND E.J. BARRETT. Growth hormone acutely
stimulates skeletal muscle but not whole-body protein synthesis in humans. Metabolism 42:1223–1227. 1993.
Effects of heavy-resistance training on hormonal response patterns in younger vs. older men
- W J Kraemer
- K Kkinen
- R U Newton
- B C Nindl
- J S Volek
- M Mccormick
- L A Gotshalk
- S E Gordon
- S J Fleck
- W W Campbell
- M Putukian
- W J Evans
KRAEMER, W.J., K. HÄ KKINEN, R.U. NEWTON, B.C. NINDL, J.S.
VOLEK, M. MCCORMICK, L.A. GOTSHALK, S.E. GORDON, S.J.
FLECK, W.W. CAMPBELL, M. PUTUKIAN, AND W.J. EVANS. Effects of heavy-resistance training on hormonal response patterns in younger vs. older men. J. Appl. Physiol. 87:982-992.
1999.