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The purpose of this study was to investigate the effects of training muscle groups 1 day per week using a split-body routine versus 3 days per week using a total-body routine on muscular adaptations in well-trained men. Subjects were 20 male volunteers (height = 1.76 ± 0.05 m; body mass = 78.0 ± 10.7 kg; age = 23.5 ± 2.9 years) recruited from a university population. Participants were pair-matched according to baseline strength and then randomly assigned to 1 of 2 experimental groups: a split-body routine (SPLIT) where multiple exercises were performed for a specific muscle group in a session with 2-3 muscle groups trained per session (n = 10), or; a total-body routine (TOTAL), where 1 exercise was performed per muscle group in a session with all muscle groups trained in each session (n = 10). Subjects were tested pre- and post-study for 1 repetition maximum strength in the bench press and squat, and muscle thickness of forearm flexors, forearm extensors, and vastus lateralis. Results showed significantly greater increases in forearm flexor muscle thickness for TOTAL compared to SPLIT. No significant differences were noted in maximal strength measures. The findings suggest a potentially superior hypertrophic benefit to higher weekly resistance training frequencies.
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... Generally, RT frequency refers to the number of sessions performed during a specific period, usually described on a weekly basis. In addition, training frequency can also be described as the number of sessions per week (sessions·wk -1 ) in which the same muscle group is stimulated [2]. ...
... However, studies comparing different RT frequencies in trained subjects, distributed into SPLIT versus full-body routines on a volume-equated basis (same number of sets per muscle group per week), have shown controversial results. Some of these studies reported no significant differences between higher (full-body) and lower frequencies (SPLIT) [5,6], while others demonstrated a potentially better hypertrophic effect for the full-body routine [2,7]. Indeed, systematic reviews with meta-analysis showed no significant difference between higher and lower frequency on a volume-equated basis for both muscle strength [8] and hypertrophy [9] outcomes. ...
... Although it is well established that both higher and lower frequencies can generate substantial increases in muscle strength and morphological outcomes, only 7 studies have investigated the effects of different RT frequencies on morphological adaptations in trained subjects, using validated diagnostic imaging methods (e.g. ultrasound) to assess changes in muscle size [2,6,7,[10][11][12][13]. Moreover, most of the studies that specifically investigated training frequencies of 2 versus 3 days per week employed whole body measures of muscle mass (e.g., dual-energy X-ray absorptiometry), which are not as sensitive for detecting subtle changes over time as site-specific measures, such as ultrasound or magnetic resonance imaging [14]. ...
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The purpose of this study was to investigate the chronic effects of training each muscle group through a split-body routine on 2 versus 3 days per week on muscle strength and morphological adaptations in recreationally resistance-trained men with the number of sets per muscle group equated between conditions. Twenty healthy men (28.8 ± 6.1 years [range 19 to 37 years]; 172.8 ± 5.1 cm; total body mass = 70.2 ± 7.4 kg; RT experience = 3.5 ± 0.8 years [range 2 to 5 years]; RT frequency = 4.4 ± 0.5 session·wk-1) volunteered to participate in this study. Subjects were randomly assigned into 2 experimental groups: 2 sessions·wk-1 per muscle (G2x, n = 10), in which every muscle was trained twice a week with 9 sets/session, or 3 sessions·wk-1 per muscle (G3x, n = 10), in which every muscle was trained thrice a week with 6 sets/session. All other variables were held constant over the 8-week study period (training intensity: 8-12 maximum repetitions; rest intervals: 60 seconds between sets). No significant difference between conditions was observed for maximal strength in the back squat (G2x: ∆ = 51.5%; G3x: ∆ = 56.3%, p = 0.337) and bench press (G2x: ∆ = 15.4%; G3x: ∆ = 20.5%, p = 0.756), muscle thickness of the biceps brachii (G2x: ∆ = 6.9%; G3x: ∆ = 8.9%, p = 0.495), triceps brachii (G2x: ∆ = 8.4%; G3x: ∆ = 15.7%, p = 0.186), vastus lateralis (G2x: ∆ = 11.2%; G3x: ∆ = 5.0%, p = 0.082 and anterior quadriceps (rectus femoris and vastus intermedius) (G2x: ∆ = 12.1%; G3x: ∆ = 21.0%, p = 0.102). In conclusion, both G2x and G3x can result in significant increases in muscle strength and size in recreationally trained men.
... Proper manipulation of load, volume, rest and frequency is essential to improve muscular hypertrophy and muscle strength [7][8][9][10][11]. However, training frequency may be the variable that has gained the least attention and thus requires further investigation [12,13]. ...
... Training frequency is typically defined as either the total number of weekly resistance training sessions, or the number of times a given muscle group is trained per week [7,[12][13][14][15][16][17]. Previously, several studies have examined the effects of different strength training frequencies on muscular adaptations and muscle strength [1,3,4,6,9,12,18,19]. ...
... Training frequency is typically defined as either the total number of weekly resistance training sessions, or the number of times a given muscle group is trained per week [7,[12][13][14][15][16][17]. Previously, several studies have examined the effects of different strength training frequencies on muscular adaptations and muscle strength [1,3,4,6,9,12,18,19]. The majority of these studies have compared muscle group frequency and not session frequency. ...
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Background The aim of this study was to assess the efficacy of a 12-week upper/lower split- versus a full-body resistance training program on maximal strength, muscle mass and explosive characteristics. Fifty resistance untrained women were pair-matched according to baseline strength and randomized to either a full-body (FB) routine that trained all of the major muscle groups in one session twice per week, or a split-body program (SPLIT) that performed 4 weekly sessions (2 upper body and 2 lower body). Both groups performed the same exercises and weekly number of sets and repetitions. Each exercise was performed with three sets and 8–12 repetition maximum (RM) loading. Study outcomes included maximal strength, muscle mass, jump height and maximal power output. Results No between-group differences were found in any of the variables. However, both FB and SPLIT increased mean 1-RM from pre- to post-test in the bench press by 25.5% versus 30.0%, lat pulldown by 27.2% versus 26.0% and leg press by 29.2% versus 28.3%, respectively. Moreover, both FB and SPLIT increased jump height by 12.5% versus 12.5%, upper-body power by 20.3% versus 16.7% and muscle mass by 1.9% versus 1.7%, p < 0.01, respectively. Conclusions This study did not show any benefits for split-body resistance-training program compared to full-body resistance training program on measures of maximal- and explosive muscle strength, and muscle mass. Trial registration : ISRCTN81548172, registered 15. February 2022.
... As trained individuals are more likely to have greater training frequencies than less trained individuals, and the frequencies used are likely to be greater than those investigated in most studies (Strömbäck et al., 2018), a need for more research on this group has been expressed (Grgic et al., 2018;Ralston et al., 2018). To our knowledge, there are ten published studies on volume equated resistance training frequency in trained individuals published to date (McLester et al., 2000;Schoenfeld et al., 2015;Brigatto et al., 2018;Colquhoun et al., 2018;Gentil et al., 2018;Gomes et al., 2019;Lasevicius et al., 2019;Saric et al., 2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). Five of these studies have focused on higher frequencies than 3 days per week (Colquhoun et al., 2018;Gomes et al., 2019;Saric et al., 2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). ...
Article
Background: Postural balance represents a fundamental movement skill for the successful performance of everyday and sport-related activities. There is ample evidence on the effectiveness of balance training on balance performance in athletic and non-athletic population. However, less is known on potential transfer effects of other training types, such as plyometric jump training (PJT) on measures of balance. Given that PJT is a highly dynamic exercise mode with various forms of jump-landing tasks, high levels of postural control are needed to successfully perform PJT exercises. Accordingly, PJT has the potential to not only improve measures of muscle strength and power but also balance. Objective: To systematically review and synthetize evidence from randomized and non-randomized controlled trials regarding the effects of PJT on measures of balance in apparently healthy participants. Methods: Systematic literature searches were performed in the electronic databases PubMed, Web of Science, and SCOPUS. A PICOS approach was applied to define inclusion criteria, (i) apparently healthy participants, with no restrictions on their fitness level, sex, or age, (ii) a PJT program, (iii) active controls (any sport-related activity) or specific active controls (a specific exercise type such as balance training), (iv) assessment of dynamic, static balance pre- and post-PJT, (v) randomized controlled trials and controlled trials. The methodological quality of studies was assessed using the Physiotherapy Evidence Database (PEDro) scale. This meta-analysis was computed using the inverse variance random-effects model. The significance level was set at p < 0.05. Results: The initial search retrieved 8,251 plus 23 records identified through other sources. Forty-two articles met our inclusion criteria for qualitative and 38 for quantitative analysis (1,806 participants [990 males, 816 females], age range 9–63 years). PJT interventions lasted between 4 and 36 weeks. The median PEDro score was 6 and no study had low methodological quality (�3). The analysis revealed significant small effects of PJT on overall (dynamic and static) balance (ES = 0.46; 95% CI = 0.32–0.61; p < 0.001), dynamic (e.g., Y-balance test) balance (ES = 0.50; 95% CI = 0.30–0.71; p < 0.001), and static (e.g., flamingo balance test) balance (ES = 0.49; 95% CI = 0.31–0.67; p<0.001). The moderator analyses revealed that sex and/or age did not moderate balance performance outcomes. When PJT was compared to specific active controls (i.e., participants undergoing balance training, whole body vibration training, resistance training), both PJT and alternative training methods showed similar effects on overall (dynamic and static) balance (p = 0.534). Specifically, when PJT was compared to balance training, both training types showed similar effects on overall (dynamic and static) balance (p = 0.514). Conclusion: Compared to active controls, PJT showed small effects on overall balance, dynamic and static balance. Additionally, PJT produced similar balance improvements compared to other training types (i.e., balance training). Although PJT is widely used in athletic and recreational sport settings to improve athletes’ physical fitness (e.g., jumping; sprinting), our systematic review with meta-analysis is novel in as much as it indicates that PJT also improves balance performance. The observed PJT-related balance enhancements were irrespective of sex and participants’ age. Therefore, PJT appears to be an adequate training regime to improve balance in both, athletic and recreational settings.
... As trained individuals are more likely to have greater training frequencies than less trained individuals, and the frequencies used are likely to be greater than those investigated in most studies (Strömbäck et al., 2018), a need for more research on this group has been expressed (Grgic et al., 2018;Ralston et al., 2018). To our knowledge, there are ten published studies on volume equated resistance training frequency in trained individuals published to date (McLester et al., 2000;Schoenfeld et al., 2015;Brigatto et al., 2018;Colquhoun et al., 2018;Gentil et al., 2018;Gomes et al., 2019;Lasevicius et al., 2019;Saric et al., 2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). Five of these studies have focused on higher frequencies than 3 days per week (Colquhoun et al., 2018;Gomes et al., 2019;Saric et al., 2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). ...
Article
Studies comparing children and adolescents from different periods have shown that physical activity and fitness decreased in the last decades, which might have important adverse health consequences such as body fat gain and poor metabolic health. The purpose of the current article is to present the benefits of high-intensity multimodal training (HIMT), such as CrossFit, to young people, with a critical discussion about its potential benefits and concerns. During HIMT, exercise professionals might have an opportunity to promote positive changes in physical function and body composition in children and adolescents, as well as to promote improvements in mental health and psychosocial aspects. Moreover, this might serve as an opportunity to educate them about the benefits of a healthy lifestyle and overcome the perceived barriers for being physically active. In technical terms, the characteristics of HIMT, such as, the simultaneous development of many physical capacities and diversity of movement skills and exercise modalities might be particularly interesting for training young people. Many concerns like an increased risk of injury and insufficient recovery might be easily addressed and not become a relevant problem for this group.
... As trained individuals are more likely to have greater training frequencies than less trained individuals, and the frequencies used are likely to be greater than those investigated in most studies (Strömbäck et al., 2018), a need for more research on this group has been expressed (Grgic et al., 2018;Ralston et al., 2018). To our knowledge, there are ten published studies on volume equated resistance training frequency in trained individuals published to date (McLester et al., 2000;Schoenfeld et al., 2015;Brigatto et al., 2018;Colquhoun et al., 2018;Gentil et al., 2018;Gomes et al., 2019;Lasevicius et al., 2019;Saric et al., 2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). Five of these studies have focused on higher frequencies than 3 days per week (Colquhoun et al., 2018;Gomes et al., 2019;Saric et al., 2019;Zaroni et al., 2019;Johnsen and van den Tillaar, 2021). ...
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The main goal of the current study was to compare the effects of volume-equated training frequency on gains in muscle mass and strength. In addition, we aimed to investigate whether the effect of training frequency was affected by the complexity, concerning the degrees of freedom, of an exercise. Participants were randomized to a moderate training frequency group (two weekly sessions) or high training frequency group (four weekly sessions). Twenty-one participants (male: 11, female: 10, age: 25.9 ± 4.0) completed the 9-week whole-body progressive heavy resistance training intervention with moderate ( n = 13) or high ( n = 8) training frequency. Whole-body and regional changes in lean mass were measured using dual-energy x-ray absorptiometry, while the vastus lateralis thickness was measured by ultrasound. Changes in muscle strength were measured as one repetition maximum for squat, hack squat, bench press, and chest press. No differences between groups were observed for any of the measures of muscle growth or muscle strength. Muscle strength increased to a greater extent in hack squat and chest press than squat and bench press for both moderate (50 and 21% vs. 19 and 14%, respectively) and high-frequency groups (63 and 31% vs. 19 and 16%, respectively), with no differences between groups. These results suggest that training frequency is less decisive when weekly training volume is equated. Further, familiarity with an exercise seems to be of greater importance for strength adaptations than the complexity of the exercise.
... [63][64][65] Athletes requiring hypertrophy need large weekly training volumes of 3 or more sessions per week. 66 Muscle hypertrophy theoretically translates to increased muscle strength. 67,68 Both low-load and high-load training can effectively increase muscle hypertrophy, although high-load training is more effective at also enhancing muscle strength. ...
Article
There is a need to improve the quality of rehabilitation in sports medicine to return athletes to optimal function safely and quickly, reducing the risk of reinjury. This paper describes a planning paradigm to guide clinical reasoning during individual treatment sessions and a model for planning the rehabilitation program from acute injury to return to play. The design of a rehabilitation program should be a collaborative, team effort, and accounting for the specific needs of the athlete. As the athlete progresses from acute injury management all the way back to full competition, the rehabilitation professional emphasizes the components of pain management , motion, motor control, and force production in varying degrees based upon phases of tissue healing and the athlete's response. Utilizing high-value, evidence-based treatments maximize both the effectiveness and efficiency of rehabilitation to restore and improve upon preinjury levels of physical performance.
... In support, the authors show excellent reliability for cross-sectional area, muscle thickness, and echo intensity determined from panoramic and a single transverse image for the biceps brachii with strong a strong association between muscle cross-sectional area and muscle thickness (r = 0.93). The interrater image acquisition reliability values for muscle thickness obtained in the transverse and sagittal planes show good-excellent reliability with minimal difference values sensitive enough to detect resistance training-induced increases in muscle thickness following longer (>6 weeks) training interventions [5,27,28], but likely not short-term training induced hypertrophy [29]. The SEM for muscle thickness measurements during acquisition are similar to those shown by a single experienced sonographer [30] and those by Mayer et al. [11] with raters of different experience level. ...
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The amount of experience with ultrasonography may influence measurement outcomes while images are acquired or analyzed. The purpose of this study was to identify the interrater reliability of ultrasound image acquisition and image analysis between experienced and novice sonographers and image analysts, respectively. Following a brief hands-on training session (2 h), the experienced and novice sonographers and analysts independently performed image acquisition and analyses on the biceps brachii, vastus lateralis, and medial gastrocnemius in a sample of healthy participants (n = 17). Test–retest reliability statistics were computed for muscle thickness (transverse and sagittal planes), muscle cross-sectional area, echo intensity and subcutaneous adipose tissue thickness. The results show that image analysis experience generally has a greater impact on measurement outcomes than image acquisition experience. Interrater reliability for measurements of muscle size during image acquisition was generally good–excellent (ICC2,1: 0.82–0.98), but poor–moderate for echo intensity (ICC2,1: 0.43–0.77). For image analyses, interrater reliability for measurements of muscle size for the vastus lateralis and biceps brachii was poor–moderate (ICC2,1: 0.48–0.70), but excellent for echo intensity (ICC2,1: 0.90–0.98). Our findings have important implications for laboratories and clinics where members possess varying levels of ultrasound experience.
... Similar findings have been reported in prior studies with resistance-trained males. (12,13) With regard to hypertrophic adaptations, Split Workout Routine and Full-Body Workout Routine led to similar increases in upper and lower limb muscle mass. Volume is thought to be a major factor in hypertrophic adaptation. ...
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Objective: To compare the effects of different resistance training programs on measures of muscle strength and hypertrophy. Methods: Sixty-seven untrained subjects were randomized to one of two groups: Split Workout Routine (n=35), in which muscle groups were trained twice per week in an A/B split consisting of eight sets per session, or Full-Body Workout Routine (n=32), in which muscle groups were trained four times per week with four and eight sets per session. Both groups performed eight to 12 repetition maximum per set, with 60 seconds of rest between sets. Maximal strength and muscle thickness were assessed at baseline and after eight weeks of training. Results: A significant main effect of time (pre versus post) was observed for maximal strength in the bench press and squat exercises and thickness of the elbow extensor, elbow flexor and quadriceps femoris muscles. Selected variables did not differ significantly between groups. Conclusion: Resistance training twice or four times per week has similar effects on neuromuscular adaptation, provided weekly set volume is equal.
Previous research has established the role of resistance training (RT) on muscle function in adolescents, but a lack of evidence to optimize RT for enhancing muscle quality (MQ) exists. This study examined whether RT frequency is associated with MQ in a nationally representative adolescent cohort. A total of 605 adolescents (12–15 year) in NHANES were stratified based on RT frequency. MQ was calculated as combined handgrip strength divided by arm lean mass (via dual-energy X-ray absorptiometry). Analysis of covariance was adjusted for sex, race/ethnicity, and arm fat percentage; p < 0.05 was considered significant. RT frequency was associated with MQ for 2–7 day/week but not 1 day/week. When no RT was compared to 1–2 and 3–7 day/week, associations were present for 3–7 day/week but not 1–2 day/week. When comparing no RT to 1–4 and 5–7 days/week, associations existed for 5–7 day/week but not 1–4 day/week. Next, no RT was compared to 1, 2–3, and 4–7 day/week; associations were found for 4–7 day/week, while 2–3 days/wk had a borderline association (p = 0.06); there were no associations for 1 day/week. Finally, no RT was compared to 1, 2, 3, 4, and 5–7 day/week; associations were present for all except 1 and 3 day/week. These prospective data suggest a minimum RT frequency of 2 day/week is associated with MQ in adolescents as indicated by the lack of differences in MQ between 1 day/week RT versus no RT.
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To compare the physiological and performance adaptations between periodized and nonperiodized resistance training in women collegiate tennis athletes. Thirty women (19 +/- 1 yr) were assigned to either a periodized resistance training group (P), nonperiodized training group (NV), or a control group (C). Assessments for body composition, anaerobic power, VO2(max), speed, agility, maximal strength, jump height, tennis-service velocity, and resting serum hormonal concentrations were performed before and after 4, 6, and 9 months of resistance training performed 2-3 d.wk (-1). Nine months of resistance training resulted in significant increases in fat-free mass; anaerobic power; grip strength; jump height; one-repetition maximum (1-RM) leg press, bench press, and shoulder press; serve, forehand, and backhand ball velocities; and resting serum insulin-like growth factor-1, testosterone, and cortisol concentrations. Percent body fat and VO2(max) decreased significantly in the P and NV groups after training. During the first 6 months, periodized resistance training elicited significantly greater increases in 1-RM leg press (9 +/- 2 vs 4.5 +/- 2%), bench press (22 +/- 5 vs 11 +/- 8%), and shoulder press (24 +/- 7 vs 18 +/- 6%) than the NV group. The absolute 1-RM leg press and shoulder press values in the P group were greater than the NV group after 9 months. Periodized resistance training also resulted in significantly greater improvements in jump height (50 +/- 9 vs 37 +/- 7%) and serve (29 +/- 5 vs 16 +/- 4%), forehand (22 +/- 3 vs 17 +/- 3%), and backhand ball velocities (36 +/- 4 vs 14 +/- 4%) as compared with nonperiodized training after 9 months. These data demonstrated that periodization of resistance training over 9 months was superior for enhancing strength and motor performance in collegiate women tennis players.
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Regimented resistance training has been shown to promote marked increases in skeletal muscle mass. Although muscle hypertrophy can be attained through a wide range of resistance training programs, the principle of specificity, which states that adaptations are specific to the nature of the applied stimulus, dictates that some programs will promote greater hypertrophy than others. Research is lacking, however, as to the best combination of variables required to maximize hypertophic gains. The purpose of this study was to investigate muscular adaptations to a volume-equated bodybuilding-type training program versus a powerlifting-type routine in well-trained subjects. 17 young men were randomly assigned to either an HT group that performed 3 sets of 10RM with 90 seconds rest or an ST group that performed 7 sets of 3RM with 3 minutes rest. After 8 weeks, no significant differences were noted in muscle thickness of the biceps brachii. Significant strength differences were found in favor of ST for the 1RM bench press and a trend was found for greater increases in the 1RM squat. In conclusion, this study showed both bodybuilding- and powerlifting-type training promote similar increases in muscular size, but powerlifting-type training is superior for enhancing maximal strength.
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The purpose of this study was to investigate the time course of hypertrophic adaptations in both the upper arm and trunk muscles following high-intensity bench press training. Seven previously untrained young men (aged 25 ± 3 years) performed free-weight bench press training 3 days (Monday, Wednesday and Friday) per week for 24 weeks. Training intensity and volume were set at 75% of one repetition maximum (1-RM) and 30 repetitions (3 sets of 10 repetitions, with 2-3 min of rest between sets), respectively. Muscle thickness (MTH) was measured using B-mode ultrasound at three sites: the biceps and triceps brachii and the pectoralis major. Measurements were taken a week prior to the start of training, before the training session on every Monday and 3 days after the final training session. Pairwise comparisons from baseline revealed that pectoralis major MTH significantly increased after week-1 (p = 0.002), triceps MTH increased after week-5 (p = 0.001) and 1-RM strength increased after week-3 (p = 0.001) while no changes were observed in the biceps MTH from baseline. Significant muscle hypertrophy was observed earlier in the chest compared to that of the triceps. Our results indicate that the time course of the muscle hypertrophic response differs between the upper arm and chest.
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Nutrient timing is a popular nutritional strategy involves the consumption of combinations of nutrients--primarily protein and carbohydrate--in and around an exercise session. Some have claimed that this approach can produce dramatic improvements in body composition. It has even been postulated that the timing of nutritional consumption may be more important than the absolute daily intake of nutrients. The post-exercise period is widely considered the most critical part of nutrient timing. Theoretically, consuming the proper ratio of nutrients during this time not only initiates the rebuilding of damaged muscle tissue and restoration of energy reserves, but it does so in a supercompensated fashion that enhances both body composition and exercise performance. Several researchers have made reference to an anabolic "window of opportunity" whereby a limited time exists after training to optimize training-related muscular adaptations. However, the importance - and even the existence - of a post-exercise 'window' can vary according to a number of factors. Not only is nutrient timing research open to question in terms of applicability, but recent evidence has directly challenged the classical view of the relevance of post-exercise nutritional intake with respect to anabolism. Therefore, the purpose of this paper will be twofold: 1) to review the existing literature on the effects of nutrient timing with respect to post-exercise muscular adaptations, and; 2) to draw relevant conclusions that allow practical, evidence-based nutritional recommendations to be made for maximizing the anabolic response to exercise.
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Previous studies have reported for the vastus lateralis (VL) that the extent of muscle hypertrophy in response to resistance training is greater in the distal than in the middle region, despite uniform muscle fibre composition within VL along its length. In the present study, to investigate mechanism(s) for such non-uniform muscle hypertrophy, we simultaneously measured neuromuscular activity and muscle oxygenation state at the middle and distal regions of VL during fatiguing heavy resistance exercise. Twelve males performed unilateral knee extension exercise which consisted of 4 sets of 8 repetitions at intensity of 80% of the individual one repetition maximum. During the resistance exercise, neuromuscular activities and muscle oxygenation status at the middle and distal regions (50% and 70% of the thigh length, respectively) of VL were measured by using electromyography and near-infrared spectroscopy, respectively. Neuromuscular activities were similar between the distal and middle regions of VL, whereas muscle tissue oxygenation saturation was significantly lower at the distal than at the middle region of VL. These results suggest a possibility that the regional difference in muscle oxygenation but not in neuromuscular activity during fatiguing heavy resistance exercise is responsible for the regional difference in hypertrophy within a muscle.
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Purpose: Muscle hypertrophy in response to resistance training has been reported to occur nonuniformly along the length of the muscle. The purpose of the present study was to examine whether the regional difference in muscle hypertrophy induced by a training intervention corresponds to the regional difference in muscle activation in the training session. Methods: Twelve young men participated in a training intervention program for the elbow extensors with a multijoint resistance exercise for 12 wk (3 d · wk(-1)). Before and after the intervention, cross-sectional areas of the triceps brachii along its length were measured with magnetic resonance images. A series of transverse relaxation time (T2)-weighted magnetic resonance images was recorded before and immediately after the first session of training intervention. The T2 was calculated for each pixel within the triceps brachii. In the images recorded after the session, the number of pixels with a T2 greater than the threshold (mean + 1 SD of T2 before the session) was expressed as the ratio to the whole number of pixels within the muscle and used as an index of muscle activation (percent activated area). Results: The percent activated area of the triceps brachii in the first session was significantly higher in the middle regions than that in the most proximal region. Similarly, the relative change in cross-sectional area induced by the training intervention was also significantly greater in the middle regions than the most proximal region. Conclusion: The results suggest that nonuniform muscle hypertrophy after training intervention is due to the region-specific muscle activation during the training session.
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There is not a strong research basis for current views of the importance of individual training variables in strength training protocol design. This study compared 1 day versus 3 days of resistance training per week in recreational weight trainers with the training volume held constant between the treatments. Subjects were randomly assigned to 1 of 2 groups: 1 day per week of 3 sets to failure (1DAY) or 3 days per week of 1 set to failure (3DAY). Relative intensity (percent of initial 1 repetition maximum [1RM]) was varied throughout the study in both groups by using a periodized repetition range of 3-10. Volume (repetitions x mass) did not differ (p <= 0.05) between the groups over the 12 weeks. The 1RMs of various upper-and lower-body exercises were assessed at baseline and at weeks 6 and 12. The 1RMs increased (p <= 0.05) significantly for the combined groups over time. The 1DAY group achieved ~62% of the 1RM increases observed in the 3DAY group in both upper-body and lower-body lifts. Larger increases in lean body mass were apparent in the 3DAY group. The findings suggest that a higher frequency of resistance training, even when volume is held constant, produces superior gains in 1RM. However, training only 1 day per week was an effective means of increasing strength, even in experienced recreational weight trainers. From a dose-response perspective, with the total volume of exercise held constant, spreading the training frequency to 3 doses per week produced superior results. (C) 2000 National Strength and Conditioning Association
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This study aimed to investigate the accuracy of estimating the volume of limb muscles (MV) using ultrasonographic muscle thickness (MT) measurements. The MT and MV of each of elbow flexors and extensors, knee extensors and ankle plantar flexors were determined from a single ultrasonographic image and multiple magnetic resonance imaging (MRI) scans, respectively, in 27 healthy men (23–40 years of age) who were allocated to validation (n=14) and cross-validation groups (n=13). In the validation group, simple and multiple regression equations using MT and a set of MT and limb length, respectively, as independent variables were derived to estimate the MV measured by MRI. However, only the multiple regression equations were cross-validated, and so the prediction equations with r 2 of 0.787–0.884 and the standard error of estimate of 22.1 cm3 (7.3%) for the elbow flexors to 198.5 cm3 (11.1%) for the knee extensors were developed using the pooled data. This approach did not induce significant systematic error in any muscle group, with no significant difference in the accuracy of estimating MV between muscle groups. In the multiple regression equations, the relative contribution of MT for predicting MV varied from 41.9% for the knee extensors to 70.4% for the elbow flexors. Thus, ultrasonographic MT measurement was a good predictor of MV when combined with limb length. For predicting MV, however, the unsuitability of a simple equation using MT only and the difference between muscle groups in the relative contribution of MT in multiple regression equations indicated a need for further research on the limb site selected and muscle analyzed for MT measurement.