Article

Effects of periodic and continued resistance training on muscle CSA and strength in previously untrained men

Authors:
To read the full-text of this research, you can request a copy directly from the authors.

Abstract

To determine muscle adaptations to retraining after short-term detraining, we examined the effects of continuous and interrupted resistance training on muscle size and strength in previously untrained men. Fifteen young men were divided into continuous training (CTr) or retraining (RTr) groups and performed high-intensity bench press training. The CTr group trained continuously for 15 weeks, while the RTr group trained for 6 weeks, stopped for a 3-week detraining period and resumed training at week 10. After the initial training phase, increases (P<0·01) in one repetition maximum (1-RM) and magnetic resonance imaging-measured triceps brachii and pectorals major muscle cross-sectional areas (CSAs) were similar in both groups. Muscle CSA and 1-RM increased (P<0·05) continuously for the CTr group, but the muscle adaptations were lower (P<0·05) after the last 6-week training period than after the initial phase. In the RTr group, there were no significant decreases in muscle CSA and 1-RM after the 3-week detraining period, and increases in muscle CSA after retraining were similar to those observed after initial training. Ultimately, improvements in 1-RM and muscle CSA in both groups were similar after the 15-week training period. Our results suggest that compared with continuous 15-week training, 3-week detraining does not inhibit muscle adaptations.

No full-text available

Request Full-text Paper PDF

To read the full-text of this research,
you can request a copy directly from the authors.

... Muscle size is a well-known predictor of the ability to produce force in athletes (Sugisaki et al., 2018), healthy individuals (Evangelidis et al., 2016;Trezise et al., 2016;Vidt et al., 2012) or clinical population (Grimaldi et al., 2009). Muscle volume (MV) and anatomical crosssectional area (CSA) are measurements of muscle size [often measured by magnetic resonance imaging (MRI)] that presents a strong relationship (r > 0.73) with muscle strength (Bamman et al., 2000;Ogasawara et al., 2011Ogasawara et al., , 2013bTrezise et al., 2016). MRI is an established technique used to assess muscle size, but it involves timing-consuming analysis. ...
... The pectoralis major muscle (PM) is a well-investigated muscle given it is important to sports performance (Marques et al., 2007;Tarity et al., 2014), and it is one of the main agonist muscles involved in a well-used strength training exercise, the bench press (Lauver et al., 2016;Ogasawara et al., 2013a). Considering the relationship between muscle size and strength (Bamman et al., 2000;Ogasawara et al., 2013bOgasawara et al., , 2011Trezise et al., 2016;Vidt et al., 2012), it would be expected that larger PM would potentially reflect in a higher ability to produce force. The PM muscle size-strength relationship, to date, was reported only once (Akagi et al., 2014). ...
... Authors correlated muscle size (CSA) and maximal dynamic strength [by one-repetition maximum (1RM)], and found an strong relationship (r = 0.86) (Akagi et al., 2014). Additionally, all the previous studies calculate PM muscle size by CSA (Akagi et al., 2014;Ogasawara et al., 2013bOgasawara et al., , 2013aOgasawara et al., , 2011Yasuda et al., 2015Yasuda et al., , 2011bYasuda et al., , 2011a, while two others used MV (Kubo et al., 2021;Vidt et al., 2012). Nonetheless, it is unknown if CSA or MV calculation, related to maximal isometric or dynamic strength measures, would cause a different impact on the PM muscle size-strength relationship. ...
Article
Muscle volume (MV) and anatomical cross-sectional area (CSA) are used as measures of muscle-size, but determining these from magnetic resonance imaging (MRI) is a very time-consuming process. Additionally, it is unclear if the use of different muscle size assessments (all vs. reduced number of slices images) would impact the muscle size-strength relationship. Thus, this study aimed to investigate if muscle size calculation by using a reduced or all slices images from pectoralis major (PM) would maintain a similar muscle size-strength relationship with bilateral maximal dynamic and isometric contractions on a bench press exercise. Twenty-four healthy males underwent an MRI examination to measure PM muscle size, and maximal isometric and dynamic contractions (by one repetition maximum, 1RM) were performed. Correlations between maximal isometric voluntary force (MVF) and dynamic strength (1RM) with muscle size variables [three images from the largest part of PM (CSA3MAX), three images accounting for the shape -first image, middle image, final image- of the PM (CSA3), and MV] were performed. The correlation between 1RM with MV, CSA3, and CSA3MAX were 0.84, 0.832, and 0.727 (p<0.001), respectively. The correlation between MVF with MV, CSA3, and CSA3MAX were 0.738, 0.733, and 0.604 (p<0.001), respectively. Overall, PM MV and CSA3 exhibit a stronger and similar muscle size-strength relationship during maximal dynamic and isometric tests than CSA3MAX. Therefore, a reduced number of slices (CSA3) could be used as an alternative to considerably reduce the time of analysis without compromise muscle size-strength relationship.
... Thus, attenuating loss of neuromuscular capability during this period is essential to ensure performance is not compromised when competition resumes. When interpreting the available resistance training research, it appears that strength may be partially or completely maintained in the short term (e.g., up to 3 weeks) [22] but will be compromised after 4 weeks (e.g., surfing athletes) [23] and begin to decay in team-sport athletes [24] and/or be substantially lost after 5 weeks without training in physically active males [25]. Tran et al. [23] also noted a reduction in athletes' sensorimotor ability which may be an important consideration where technical and/or skillful actions are required (e.g., complex WL movements). ...
... Ogasawara et al. [22] Untrained men, 24.7 ± 2.5 y (n = 15) ...
... Further, support for a muscle memory effect in humans comes from Ogasawara et al. [52] who showed that rates of muscle and strength re-adaptation occurred faster when subsequent 6-week training blocks were separated by 3-week non-training phases in the bench press exercise. This finding has also been supported by the authors earlier work [22], and importantly, the amount and overall magnitude of the adaptation was not dissimilar to 15 weeks of continuous resistance training. Although limited evidence exists looking at this phenomenon with human subjects, the collective animal and preliminary human evidence provides support that previously trained strength athletes may undergo a greater rate of muscle adaptation once training is resumed (for theoretical depiction refer to Figure 1). ...
Article
Full-text available
The ongoing global pandemic brought about by Coronavirus II (SARS-Cov-2 or COVID-19) has caused an ongoing cessation of sporting competitions and training facility closures. This is a fundamental challenge for amateur and elite sporting professionals. Although recommendations have been provided for team-sport athletes to maintain general and sport-specific conditioning, these methods are often not optimal for strength athletes (i.e., powerlifting (PL) and weightlifting (WL)) due to the unique and narrow set of performance requirements posed by these sports. The purpose of this review is to provide evidence-based information and recommendations and highlight potential strategies and approaches that may be used by strength (PL and WL) athletes during the current global crisis. Collectively, we provide evidence from resistance training literature regarding the loss of muscle strength, power and mass, minimum training frequencies required to attenuate such losses and training re-adaptation. Additionally, we suggest that time off training and competition caused by ongoing restrictions may be used for other purposes, such as overcoming injury and improving movement quality and/or mobility, goal setting, psychological development and emphasizing strength sports for health. These suggestions are intended to be useful for coaches, strength athletes and organizations where existing training strategies and recommendations are not suitable or no longer feasible.
... Finally Ogasawara et al. published two studies comparing continuous and non-continuous resistance training [128,129]. The earlier study [128] compared two groups, performing either continuous training for 15 weeks (CTR) or a group that trained for 6 weeks, went untrained for 3 weeks, and then retrained for a further 6 weeks (RTR) using free-weight bench press. ...
... Finally Ogasawara et al. published two studies comparing continuous and non-continuous resistance training [128,129]. The earlier study [128] compared two groups, performing either continuous training for 15 weeks (CTR) or a group that trained for 6 weeks, went untrained for 3 weeks, and then retrained for a further 6 weeks (RTR) using free-weight bench press. The initial 6-weeks showed significant increases in hypertrophy of the triceps brachii (TB) and pectoralis major (PM) with no significant difference between CTR and RTR groups. ...
... Exercising a contralateral limb appears not to stimulate hypertrophic gains in an untrained limb, although evidence suggests that it might reduce the rate of atrophy [124,125]. Finally untrained persons appear to be capable of making significant hypertrophic gains within 3 weeks of starting resistance training [81,88] whilst trained persons are encouraged to allow adequate rest (up to ~3 weeks) [122,128,129] between training sessions without fear of atrophy. ...
Article
Full-text available
Objective: There is considerable interest in attaining muscular hypertrophy in recreational gym-goers, bodybuilders, older adults, and persons suffering from immunodeficiency conditions. Multiple review articles have suggested guidelines for the most efficacious training methods to obtain muscular hypertrophy. Unfortunately these included articles that inferred hypertrophy markers such as hormonal measurements, used older techniques that might not be valid (e.g. circumference) and failed to appropriately consider the complexity of training variables. Methods: The present commentary provides a narrative review of literature, summarising main areas of interest and providing evidence-based guidelines towards training for muscular hypertrophy. Conclusions: Evidence supports that persons should train to the highest intensity of effort, thus recruiting as many motor units and muscle fibres as possible, self-selecting a load and repetition range, and performing single sets for each exercise. No specific resistance type appears more advantageous than another, and persons should consider the inclusion of concentric, eccentric and isometric actions within their training regime, at a repetition duration that maintains muscular tension. Between set/exercise rest intervals appear not to affect hypertrophy, and in addition the evidence suggests that training through a limited range of motion might stimulate similar results to full range of motion exercise. The performance of concurrent endurance training appears not to negatively affect hypertrophy, and persons should be advised not to expect uniform muscle growth both along the belly of a muscle or for individual muscles within a group. Finally evidence suggests that short (~3 weeks) periods of detraining in trained persons does not incur significant muscular atrophy and might stimulate greater hypertrophy upon return to training. Key words: muscular size, bodybuilding, intensity, genetics, concurrent, endurance
... The improvement in muscle size and function are acquired over several weeks or months of continuous resistance training performed without periods of interruption ( Kraemer, et al ., 2002 ;ACSM, 2009 ). It has been reported that interruption or detraining periods in these studies was diff erent between continuous and periodic training groups ( Ogasawara, et al ., 2011 ;Ogasawara, Yasuda, et al ., 2013 ), and another study did not use a continuous training group in the experimental design ( Häkkinen, et al ., 2000 ). The non-equalized number of training sessions is an important source of bias since it is one of the most important acute variables for strength gain ( Gillam, 1981 ;McLester, Bishop, & Guilliams, 2000 ;Rhea, Alvar, Burkett, & Ball, 2003 ;ACSM, 2009 ). ...
... The non-equalized number of training sessions is an important source of bias since it is one of the most important acute variables for strength gain ( Gillam, 1981 ;McLester, Bishop, & Guilliams, 2000 ;Rhea, Alvar, Burkett, & Ball, 2003 ;ACSM, 2009 ). Furthermore, in the aforementioned studies ( Ogasawara, et al ., 2011 ;Ogasawara, Yasuda, et al ., 2013 ) only lower ( Häkkinen, et al ., 2000 ) or upper limbs ( Ogasawara, et al ., 2011;Ogasawara, Yasuda, et al ., 2013 ) were evaluated, whereas no study has simultaneously assessed strength gains of the lower and upper limbs after continuous and periodic resistance training using the same training volume. ...
... The non-equalized number of training sessions is an important source of bias since it is one of the most important acute variables for strength gain ( Gillam, 1981 ;McLester, Bishop, & Guilliams, 2000 ;Rhea, Alvar, Burkett, & Ball, 2003 ;ACSM, 2009 ). Furthermore, in the aforementioned studies ( Ogasawara, et al ., 2011 ;Ogasawara, Yasuda, et al ., 2013 ) only lower ( Häkkinen, et al ., 2000 ) or upper limbs ( Ogasawara, et al ., 2011;Ogasawara, Yasuda, et al ., 2013 ) were evaluated, whereas no study has simultaneously assessed strength gains of the lower and upper limbs after continuous and periodic resistance training using the same training volume. ...
Article
Full-text available
-It has been reported that periodic resistance training (retraining after short-term detraining) could maintain muscle performance. However, the training volume used in previous studies differed between continuous and periodic training groups. This study compared strength gains following 20 sessions of continuous and periodic resistance training programs. 60 healthy, detrained women were randomly assigned into one of two groups: (1) continuous resistance training group or (2) retraining resistance group. The continuous resistance training group performed a non-interrupted resistance training program for 10 wk., while the retraining resistance group trained for 5 wk., detrained 2 wk., and resumed training for 5 wk. All participants performed three sets of 8-12 maximum repetitions of lower- and upper-body exercises two days per week, with at least 48 hr. between sessions. There was no significant difference on knee extensors and elbow flexors peak torque gain between the continuous resistance training group and the retraining resistance group. The results suggest that 2 wk. of detraining does not affect strength gains after a total of 10 wk. in detrained women.
... 8,17 Our search returned 5 studies that measured posterior upper arm muscle size. 8,11,13,17,18 Compared with the anterior upper arm, a statistically significant increase in muscle size from baseline of the posterior upper arm appeared to occur later, at about 6 weeks. 8,13,17,18 There was less agreement regarding when a plateau occurred, with a range of 6 8 -15 13 weeks. ...
... 8,11,13,17,18 Compared with the anterior upper arm, a statistically significant increase in muscle size from baseline of the posterior upper arm appeared to occur later, at about 6 weeks. 8,13,17,18 There was less agreement regarding when a plateau occurred, with a range of 6 8 -15 13 weeks. ...
... Chest. Only 4 studies measuring chest muscle size were found, 8,13,17,18 with increases ranging from 12% to 40%. 8,17 An initial statistically significant increase in muscle size from baseline occurred at about 3 13 and 6 8,17 weeks. ...
Article
Strength increases following training are thought to be influenced first by neural adaptions, and second by large contributions from muscle growth. This is largely based on the idea that muscle growth is a slow process and a plateau in muscle growth would substantially hinder long term increases in strength. Our purpose was to review the literature to better determine the time course of skeletal muscle growth in the upper and lower body, and to determine if and when muscle growth plateaus. Studies were included if they had at least three muscle size time points, participants ≥ 18 years old, and used a resistance training protocol. Muscle growth occurs sooner than once hypothesized and this adaptation is specific to the muscle group. Further, the available studies indicate that the muscle growth response will plateau, and further growth is not likely to appreciably occur beyond this initial plateau. However, the current study durations are a limitation. This article is protected by copyright. All rights reserved.
... The literature on DTR in adults on body composition, MM, strength, and power is very heterogeneous. Previous research has shown that short-term DTR (≤ 8 weeks) lead to an increase in fat mass (FM) (11) and decreases in muscle cross-sectional area (CSA) (11), whereas others found neither FM (16) nor CSA changes (27). Furthermore, studies have found a reduction in one-repetition maximum (1-RM) (back squat [BS] (11,16) and bench press [BP] (16)), while other studies did not (27). ...
... Previous research has shown that short-term DTR (≤ 8 weeks) lead to an increase in fat mass (FM) (11) and decreases in muscle cross-sectional area (CSA) (11), whereas others found neither FM (16) nor CSA changes (27). Furthermore, studies have found a reduction in one-repetition maximum (1-RM) (back squat [BS] (11,16) and bench press [BP] (16)), while other studies did not (27). Jumping ability was also negatively affected in some DTR studies (16), while others showed no decline (11). ...
... More accurate methods, such as Dual-energy X-ray absorptiometry, should be considered in future studies. The preservation of MM has also been reported in several other studies with adults (15,27). ...
Article
Full-text available
The purpose of this study was to examine the effects of detraining following a block (BLOCK) or daily undulating periodized (DUP) resistance training (RT) on hypertrophy, strength, and athletic performance in adolescent athletes. Twenty-one males (age = 16 ± 0.7 years; range 15-18 years) were randomly assigned to one of two 12-week intervention groups (three full-body RT sessions per week): BLOCK (n = 9); DUP (n = 12). Subsequently a three-week detraining period was applied. Body mass, fat mass (FM), fat-free mass (FFM), muscle mass, muscle thickness (rectus femoris, vastus lateralis and triceps brachii), one-repetition maximum squat and bench press, countermovement jump (CMJ), peak power calculated from CMJ (Ppeak), medicine ball put distance, and 36.58m sprint were recorded before and after RT as well as after detraining. BLOCK and DUP were equally effective for improvements of athletic performance in young athletes. Both groups displayed significantly (ρ ≤ 0.05) higher values of all measures after RT except FM, which was unchanged. Only FM increased (p = 0.010; ES = 0.14) and FFM decreased (p = 0.018; ES =-0.18) after detraining. All other measurements were unaffected by the complete cessation of training. Values were still elevated compared to pre-training. Linear regression showed a strong correlation between the percentage change by resistance training and the decrease during detraining for CMJ (R² = 0.472) and MBP (R² = 0.629). BLOCK and DUP RT seem to be equally effective in adolescent athletes for increasing strength, muscle mass, and sport performance. In addition, three weeks of detraining did not affect muscle thickness, strength, or sport performance in adolescent athletes independent of previous resistance training periodization model used.
... Other studies have reported similar decreases in progression throughout the duration of a continuous RT intervention when compared to groups performing non-continuous training. For example, Ogasawara, et al. 18 divided participants in to continuous-(CTR) or non-continuous-training groups (RTR) for a 15-week RT intervention. The CTR group trained for 15 weeks without interval whilst the RTR group trained for 6 weeks, then rested for a 3-week detraining period, and then retrained for a further 6-weeks. ...
... It is noteworthy that none of this research considering detraining periods [18][19][20] was included in the meta-analysis by Williams,et al. 3 or discussed the systematic review by Grgic, et al. 1 In this sense, it appears that authors have defined periodized training by its variation purely in load and repetitions, rather than considering training/detraining/retraining periods. Since this appears to be the variable that determines a sustained increase throughout an intervention, and the reason why Herrick and Stone 17 reported a change in the slope of adapta-tion, it seems that this might be an important variable for consideration. ...
... Since this appears to be the variable that determines a sustained increase throughout an intervention, and the reason why Herrick and Stone 17 reported a change in the slope of adapta-tion, it seems that this might be an important variable for consideration. It should be noted that, though there were differences between the continuous and non-continuous groups in slope of improvements at different time points in the aforementioned studies, [17][18][19][20] it is naïve to assume that the rate of improvement over these short periods is in anyway indicative of what the slopes of improvement may look like over a longer period of time. The simple fact of the matter is that we do not know the degree to which the continued manipulation in any RT variable over extended periods of time might affect slope of change for any outcome variable. ...
Article
Full-text available
Objective: A growing area of discourse within sports medicine and resistance training is that of periodization. This has been represented as variation in load and subsequently repetitions as well as volume, with a view to maximize strength and hypertrophy adaptations. A number of recent review articles have attempted to draw overarching conclusions from the present body of literature in an effort to provide definitive guidelines. However, there are numerous variables within resistance training that are often overlooked, and in the context of periodization, might significantly impact adaptation. Design & Methods: Narrative Review Results: The present piece confers need for clarity in terminology of effort rather than intensity, as well as discussing how variety of load might impact volume-load, discomfort, muscle damage and recovery. Furthermore, this article discusses often overlooked variables such as variety in exercise selection, detraining periods, and supervision, which are all evidenced to impact strength and hypertrophy adaptations. Conclusions: Our opinion is that without inclusion of these variables any guidelines surrounding periodization for strength or hypertrophy are limited in application. We conclude by highlighting areas for future research, as well as practical recommendations within this field.
... Interestingly, after short-term (\1 month) cessation of training (detraining), muscle adaptation responses may return to their initial levels, and the effects of retraining after short-term cessation on muscle growth are comparable with those observed during the early phase of training (Ogasawara et al. 2011). During short-term detraining, the rate of decrease (percent change per day) in muscle CSA is similar to (Andersen et al. 2005;Narici et al. 1989) or even less than (Leger et al. 2006;Ogasawara et al. 2011) the increase in muscle CSA during the early phase of training. ...
... Interestingly, after short-term (\1 month) cessation of training (detraining), muscle adaptation responses may return to their initial levels, and the effects of retraining after short-term cessation on muscle growth are comparable with those observed during the early phase of training (Ogasawara et al. 2011). During short-term detraining, the rate of decrease (percent change per day) in muscle CSA is similar to (Andersen et al. 2005;Narici et al. 1989) or even less than (Leger et al. 2006;Ogasawara et al. 2011) the increase in muscle CSA during the early phase of training. Thus, if the detraining period is followed by a longer period of retraining, and if the retraining phase has an effect similar to that of the early phase of training, then muscle CSA may improve. ...
Article
Full-text available
To compare the effects of a periodic resistance training (PTR) program with those of a continuous resistance training (CTR) program on muscle size and function, 14 young men were randomly divided into a CTR group and a PTR group. Both groups performed high-intensity bench press exercise training [75 % of one repetition maximum (1-RM); 3 sets of 10 reps] for 3 days per week. The CTR group trained continuously over a 24-week period, whereas the PTR group performed three cycles of 6-week training (or retraining), with 3-week detraining periods between training cycles. After an initial 6 weeks of training, increases in cross-sectional area (CSA) of the triceps brachii and pectoralis major muscles and maximum isometric voluntary contraction of the elbow extensors and 1-RM were similar between the two groups. In the CTR group, muscle CSA and strength gradually increased during the initial 6 weeks of training. However, the rate of increase in muscle CSA and 1-RM decreased gradually after that. In the PTR group, increase in muscle CSA and strength during the first 3-week detraining/6-week retraining cycle were similar to that in the CTR group during the corresponding period. However, increase in muscle CSA and strength during the second 3-week detraining/6-week retraining cycle were significantly higher in the PTR group than in the CTR group. Thus, overall improvements in muscle CSA and strength were similar between the groups. The results indicate that 3-week detraining/6-week retraining cycles result in muscle hypertrophy similar to that occurring with continuous resistance training after 24 weeks.
... For example, Coburn et al. (14) reported that 8 weeks of unilateral resistance training with or without protein supplementation resulted in improvements in strength and muscle CSA in the trained limb for both groups, with the untrained limb also improving strength in the proteinsupplemented group. Without supplementation, Ogasawara et al. (41) reported marked improvements in muscle CSA (mCSA) as confirmed by magnetic resonance imaging (MRI) after 6 and 15 weeks of periodic and continuous bench press (BP) training programs in previously untrained men. In contrast, Chromiak et al. (13) showed that there were no differences in body composition, strength, muscular endurance, or power after 10 weeks of resistance training with the consumption of a creatine, whey protein, and amino acid supplement, or a carbohydrate-only supplement after exercise in recreationally active young men. ...
... Willoughby et al. (62) studied the effects of a 20-g protein or placebo drink before and after training sessions and reported improvements in markers of MPS, body composition, and performance after 10 weeks of resistance training with the protein drink. Similar to this study, Ogasawara et al. (41) reported hypertrophic responses after similar training volume was implemented in previously trained individuals using BP, as indicated by changes in mCSA measured by MRI. Conversely, studies by Verdijk et al. (57) and DeNysschen et al. (19) reported no differences in muscle hypertrophy, performance, or body composition among protein and placebo or whey protein and soy protein groups, respectively, after 12 weeks of resistance training. ...
Article
Full-text available
The purpose of this study was to examine the effects of two different types of protein supplementation on thigh muscle cross-sectional area, blood markers, muscular strength, endurance, and body composition after eight weeks of low- or moderate-volume resistance training in healthy, recreationally trained, college-aged men. One hundred and six men were randomized into five groups: low-volume resistance training with bio-enhanced whey protein (BWPLV; n=22), moderate-volume resistance training with BWP (BWPMV; n=20), moderate-volume resistance training with standard whey protein (SWPMV; n=22), moderate-volume resistance training with a placebo (PLA; n=21), or moderate-volume resistance training with no supplementation (CON; n=21). Except for CON, all groups consumed one shake before and after each exercise session and one each non-training day. The BWPLV, BWPMV, and SWPMV groups received approximately 20g of whey protein per shake, while the BWP groups received 5g additional polyethylene glycosylated (PEG) leucine. Resistance training sessions were performed three times per week for eight weeks. There were no interactions (p>0.05) for muscle strength and endurance variables, body composition, muscle cross-sectional area, and safety blood markers, but main effects for training were observed (p≤0.05). However, Albumin:Globulin ratio for SWPMV was lower (p=0.037) than BWPLV and BWPMV. Relative protein intake (PROREL) indicated a significant interaction (p<0.001) with no differences across groups at pre, however, BWPLV, BWPMV, and SWPMV had a greater intake than PLA or CON at post (p<0.001). The present study indicated that eight weeks of resistance training improved muscle performance and size similarly among groups regardless of supplementation.
... The recommendations are based on research on detraining showing that reduced activity can lead to decreases in muscle strength (2,32,59,131), aerobic capacity (73,127,130,131), anaerobic capacity (73,93,137), and induce skeletal muscle atrophy (32,59,78,100,101,132). These decrements are seen in a wide range of ages (2,67,78,105,135), potentially inducing injury or illness. Although some studies Gradual increase over 5 weeks (Table 9), followed by FIT rule limitations for 1 week. ...
... Retraining following short detraining periods can induce restorative improvements in aerobic and anaerobic performances (73,100,127), as well as muscular strength and hypertrophy (67, 105,106,132,134). Retraining is especially effective for developing muscle strength and hypertrophy as there is evidence that the myonuclei obtained during hypertrophy are maintained even during extreme atrophy (13,55). ...
Article
Full-text available
THE INCIDENCE OF INJURIES AND DEATHS RELATED TO EXERTIONAL HEAT ILLNESS (EHI), EXERTIONAL RHABDOMYOLYSIS (ER), AND CARDIORESPIRATORY FAILURE HAS INCREASED SIGNIFICANTLY IN COLLEGE ATHLETES IN RECENT YEARS. DATA INDICATE THAT THESE INJURIES AND DEATHS ARE MORE LIKELY TO OCCUR DURING PERIODS WHEN ATHLETES ARE TRANSITIONING FROM RELATIVE INACTIVITY TO REGULAR TRAIN- ING. TO ADDRESS THIS PROBLEM, THE CSCCA AND NSCA HAVE CREATED CONSENSUS GUIDE- LINES WHICH RECOMMEND UPPER LIMITS ON THE VOLUME, INTENSITY, AND WORK:REST RATIO DURING TRANSITION PERI- ODS WHERE ATHLETES ARE MOST VULNERABLE. THE CONSENSUS GUIDELINES PROVIDE STRENGTH AND CONDITIONING COACHES WITH A CLEAR FRAMEWORK FOR SAFE AND EFFECTIVE PROGRAM DESIGN IN THE FIRST 2-4 WEEKS FOLLOWING PERIODS OF INAC- TIVITY OR RETURN FROM EHI OR ER. ADHERING TO THE CONSEN- SUS GUIDELINES, CONDUCTING PREPARTICIPATION MEDICAL EVALUATIONS, AND ESTABLISH- ING EMERGENCY ACTION PLANS WILL REDUCE THE INCIDENCE OF INJURIES AND DEATHS IN COL- LEGE ATHLETES
... Although subjects were untrained in the present study, these findings were similar to those of Hortobagyi et al. [34], who reported two weeks of detraining in resistance-trained athletes did not cause a significant decrease in maximal bench press, squat, isometric, or concentric isokinetic strength [34]. In addition, Ogasawara et al. [51] demonstrated strength was maintained following a three-week detraining period in previously untrained men [51]. Similarly, Shaver [61] found that recently acquired strength can be maintained in both trained and untrained limb for up to one week [61]. ...
... Although subjects were untrained in the present study, these findings were similar to those of Hortobagyi et al. [34], who reported two weeks of detraining in resistance-trained athletes did not cause a significant decrease in maximal bench press, squat, isometric, or concentric isokinetic strength [34]. In addition, Ogasawara et al. [51] demonstrated strength was maintained following a three-week detraining period in previously untrained men [51]. Similarly, Shaver [61] found that recently acquired strength can be maintained in both trained and untrained limb for up to one week [61]. ...
Article
Full-text available
Purpose: To examine and compare the effects of three days of dynamic constant external resistance (DCER) and isokinetic (ISOK) training and subsequent detraining on thigh muscle cross-sectional area (TMCSA) and thigh lean mass (TLM), ISOK peak torque (PT), DCER strength, isometric force, muscle activation, and percent voluntary activation (%VA). Methods: Thirty-one apparently-healthy untrained men (mean ± SD age = 22.2 ± 4.2 years; body mass = 77.9 ± 12.9 kg; height = 173.9 ± 5.4 cm) were randomly assigned to a DCER training group (n = 11), ISOK training group (n = 10) or control (CONT) group (n = 10). Subjects visited the laboratory eight times. The first visit was a familiarization session, the second visit was a pre-training assessment, the subsequent three visits were for unilateral training of the quadriceps (if assigned to a training group), and the last three visits were the post-training assessments conducted at three days, one week, and two weeks after training ended. Results: DCER strength increased from pre- to post-training assessment 1 in both limbs for the DCER group only, and remained elevated during post-training assessments 2 and 3 (P < 0.05). In addition, surface EMG for the biceps femoris was higher at post-training assessment 3 than at the pre-training assessment, and post-training assessments 1 and 2 (P < 0.05). No other training-related changes were found. Conclusion: The primary finding of this study was that DCER strength of the trained and untrained limbs can be increased with three days of training. This has important implications for injury rehabilitation, where in the initial period post-injury strength gains on an injured limb can possibly be obtained with short-term contralateral resistance training.
... A total sample size of 30 subjects were determined by using GPower (version 3.0.1, Germany) based on a test using an analysis of variance (ANOVA) (repeated-measures, withinbetween interaction), with an alpha level of 0.05, power of 0.80; effect size (ES) of 0.30 (obtained from the triceps brachii muscle from the study of Ogasawara et al. (21)), number of groups, 3; number of measurements, 2; correlation among measures of 0.5; and a nonsphericity correction of 1. ...
... The exercise adopted for the 2 training programs was the bench press, with all testing and training sessions performed on a Smith machine (MASTER Belo Horizonte, Brazil). The volunteers were positioned on the equipment, with the position of the hands on the bar being standardized as twice the biacromial distance with the middle finger being the reference for marking (21). It was also necessary to standardize the subjects position on the equipment. ...
Article
The aim of this study was to investigate the effects of 2 training protocols equalized by tension (TUT) on maximal strength (1 repetition maximum [RM]), regional cross-sectional areas (proximal, middle, and distal), and total cross-sectional areas (sum of the regional cross-sectional areas) of the pectoralis major and triceps brachii muscles. Thirty-eight men untrained in resistance training participated in the study and were allocated under 3 conditions: Protocol 3s (n 5 11; 12 repetitions; 3s repetition duration), Protocol 6s (n 5 11; 6 repetitions; 6s repetition duration), and Control (n 5 11; no training). Training protocols (10 weeks; bench press exercise) were equated for TUT (36 seconds per set), number of sets (3-4), intensity (50-55% of 1RM), and rest between sets (3 minutes). Analysis of variance was used to examine a percentage change in variables of interest across the 3 groups with an alpha level of 0.05 used to establish statistical significance. Protocols 3s and 6s showed no differences in the increase of total and regional muscle cross-sectional areas. There were no differences in regional hypertrophy of the pectoralis major muscle. In the triceps brachii muscle, the increase in distal cross-sectional area was greater when compared with the middle and proximal regions. Both experimental groups had similar increases in the 1RM test. In conclusion, training protocols with the same TUT promote similar strength gains and muscle hypertrophy. Moreover, considering that the protocols used different numbers of repetitions, the results indicate that training volumes cannot be considered separately from TUT when evaluating neuromuscular adaptations.
... Interruption of a training period may be related to several causes such as illness, injury, vacations, lack of time, motivation, and other factors (29,42). The magnitude of muscle loss will depend on the period of detraining; short periods of interruption, such as 3 weeks, do not inhibit the improvements in cross-sectional area and 1RM (47). Intermediate detraining periods, such as 4 to 8 months, seem to promote regression in muscle adaptations, but not returning to baseline levels (53,64). ...
Article
Full-text available
An individual’s training status is a key factor used to determine the volume, the intensity, and the selection of exercises for resistance training pre- scription. Interestingly, there are no objective parameters to assess train- ing status, so there is ambiguity in determining the appropriate volume and other resistance training variables in this regard. Thus, the objective of this study was to propose a strategy for classification and determination of resistance training status. The follow- ing five parameters were identified and used: (a) current uninterrupted training time, (b) time of detraining, (c) previous training experience, (d) exercise tech- nique, and (e) strength level. Moreover, 4 classification levels are proposed: beginner, intermediate, advanced, and highly advanced, which are determined by the mean score of the parameters used. The proposed model represents an important advancement in training status classification and can be used as a valid tool for training prescription and for researchers to better charac- terize a sample and reproduce result under the same conditions in future studies.
... Resistance training mainly changes the morphology of skeletal muscle, improves Abbreviations 4E-BP1, 4E-binding protein 1; 4HNE, 4-hydroxynonenal; Akt, protein kinase B; AMPK, AMP-activated protein kinase; EE, endurance exercise; ERK1/2, extracellular signal-regulated kinases 1/2; FoxO1, Forkhead box-containing protein O1; GSK3b, glycogen synthase kinase 3b; LC-3, microtubule-associated protein 1 light chain 3; MAFbx, Muscle Atrophy F-box; MAPK, mitogen-activated protein kinase; mTOR, mechanistic target of rapamycin; MuRF1, Muscle RING-Finger Protein; OL, overload; OL+EE30, OL and EE for 30 min; OL+EE90, OL and EE for 90 min; p70S6K, p70 S6 kinase; PGC-1a, peroxisome proliferator-activated receptor c coactivator-1a; PI3K, phosphoinositide 3-kinase; S6, S6 ribosomal protein S6; VEGF, vascular endothelial growth factor. muscle strength and promotes hypertrophy [3,4], and induces muscle hypertrophy by activating the mammalian/mechanistic target of rapamycin (mTOR) signaling pathway, which contains p70 S6 kinase (p70S6K) and S6 ribosomal protein (S6) [5]. In addition, mitogenactivated protein kinase (MAPK) signaling is activated by a variety of cellular stresses, including mechanical stress. ...
Article
Full-text available
For many ball games, both resistance and endurance training are necessary to improve muscle strength and endurance capacity. Endurance training has been reported to inhibit muscle strength and hypertrophy, but some studies have reported that endurance exercise (EE) does not inhibit the effects of resistance exercise. Here, we examined the effect of short- or long-duration EE on mouse skeletal muscle hypertrophy induced by functional overload (OL) at the molecular level. Plantaris muscle hypertrophy was induced by OL with synergist ablation in mice. Body mass was reduced with endurance training, but EE duration (30 or 90 min) had no effect. The ratio of plantaris muscle weight to body weight was higher in the OL and EE for 30 min (OL+EE30) and OL and EE for 90 min (OL+EE90) groups compared with the OL group. Expression of mechanistic target of rapamycin signaling proteins, which is related to protein synthesis and hypertrophy, was increased in the OL+EE30 group. Expression of Forkhead box-containing protein O1, which is related to protein breakdown and atrophy, remained unchanged. However, microtubule-associated protein 1 light chain 3, a known marker of autophagy, and MAFbx, which is related to protein breakdown, were significantly increased in the OL+EE90 group. Furthermore, markers of oxidative stress, ubiquitin and 4-hydroxynonenal were also significantly increased in the OL+EE90 group compared with other groups. In conclusion, EE duration did not affect body mass and plantaris mass and did not interfere with mechanistic target of rapamycin signaling, but it did increase ubiquitinated proteins and oxidative stress. It is therefore necessary to consider training durations for EE when combining endurance and resistance training.
... In addition, Abe et al. [20] observed after a 6 week total body workout (70% 1 RM), that the quadriceps muscle thickness increased 5%, however the PM and TB increased 13% and 9%, respectively. Furthermore, using a MRI, muscle CSA increased 16% in the PM and 10% in the TB following 18 days of bench press training (75% 1RM) [27]. Yasuda et al. [28] also observed that 18 days of bench press training (75% 1 RM) resulted in an 18% increase in PM and a 10% increase in the TB. ...
Article
The purpose of this study was to determine whether the training responses observed with low-load resistance exercise to volitional fatigue translates into significant muscle hypertrophy, and compare that response to high-load resistance training. Nine previously untrained men (aged 25 [SD 3] years at the beginning of the study, standing height 1.73 [SD 0.07] m, body mass 68.9 [SD 8.1] kg) completed 6-week of high load-resistance training (HL-RT) (75% of one repetition maximal [1RM], 3-sets, 3x/wk) followed by 12 months of detraining. Following this, subjects completed 6 weeks of low load-resistance training (LL-RT) to volitional fatigue (30% 1 RM, 4 sets, 3x/wk). Increases (p < 0.05) in magnetic resonance imaging-measured triceps brachii and pectorals major muscle cross-sectional areas were similar for both HL-RT (11.9% and 17.6%, respectively) and LL-RT (9.8% and 21.1%, respectively). In addition, both groups increased (p < 0.05) 1RM and maximal elbow extension strength following training; however, the percent increases in 1RM (8.6% vs. 21.0%) and elbow extension strength (6.5% vs. 13.9%) were significantly (p < 0.05) lower with LL-RT. Both protocols elicited similar increases in muscle cross-sectional area, however differences were observed in strength. An explanation of the smaller relative increases in strength may be due to the fact that detraining after HL-RT did not cause strength values to return to baseline levels thereby producing smaller changes in strength. In addition, the results may also suggest that the consistent practice of lifting a heavy load is necessary to maximize gains in muscular strength of the trained movement. These results demonstrate that significant muscle hypertrophy can occur without high-load resistance training and suggests that the focus on percentage of external load as the important deciding factor on muscle hypertrophy is too simplistic and inappropriate.
... Electromyographic studies (19,22) found that the pectoralis major muscle contributes to bench press and throw movements as with the deltoid and triceps brachii. Furthermore, bench press training (training intensity: 75% of one repetition maximum bench press strength [1RM BP ]; training volume: 30 repetitions [3 sets of 10 repetitions], with 2-3 minutes of rest between sets, 3 days per week for 6 weeks) increased the size of the pectoralis major muscle significantly in other previous studies (18,24). These suggest that the pectoralis major muscle is the agonist muscle for bench press and bench throw movements. ...
Article
This study examined the relationship of muscle size indices of the pectoralis major muscle with bench press and bench throw performances in eighteen male collegiate athletes. The maximal cross-sectional area (MCSAMAX) and volume (MV) of the pectoralis major muscle were determined by magnetic resonance imaging. First, subjects were tested for their one-repetition maximum bench press strength (1RMBP) using a Smith machine. At a later date, subjects performed bench throws using the Smith machine with several different loads ranging from 30.0 kg to 90% of 1RMBP. Barbell positions were measured by a linear position transducer, and bench throw power was calculated using a dynamic equation. Three trials were performed for each load. In all the trials, the maximal peak power was adopted as PPBT. 1RMBP was significantly correlated with MCSAMAX. Similarly, the correlation coefficient between MV and PPBT was significant. In contrast to the y-intercept of the MV-PPBT regression line, that of the MCSAMAX-1RMBP regression line was not significantly different from 0. These results suggested that, although the dependence on pectoralis major muscle size is slightly different between bench press strength and bench throw power, the pectoralis major muscle size has a significant impact on bench press and throw performances. Greater muscle size leads to heavier body weight, which can be a negative factor in some sports. We therefore recommend that athletes and their coaches develop training programs for improving sports performance by balancing the advantage of increased muscle size and the potential disadvantage of increased body weight.
... Although most studies have evaluated muscle hypertrophy and increased strength at the beginning and end of the training, fewer studies have investigated the time course of the muscle hypertrophic adaptations to heavy resistance training. These studies demonstrated that heavy resistance training-induced muscle adaptations are greater during the early phase (i.e., first ~10 weeks) of training than during the later phase [3][4][5][6] and that a significant increase in muscle size had occurred ~4 weeks following the initiation of resistance training [3,7,8]. Most of these studies observed limb muscle hypertrophy; however, very few studies report on muscle size changes of the trunk following heavy resistance training [3,9]. ...
Article
Full-text available
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.
... It is well accepted that resistance training increases skeletal muscle cross-sectional area (CSA) and the ability to generate force in both men and women regardless of age (Ikai & Fukunaga, 1970;Maughan et al., 1983;Pyka et al., 1994;Ogasawara et al., 2011). Also, a dynamic and adaptive response has been found in tendon tissue following prolonged loading (Langberg et al., 2001;Magnusson et al., 2010), with studies showing human tendons as metabolically active responding both metabolically and structurally to both loading and unloading (Langberg et al., 1999;Kjaer, 2004;Miller et al., 2005;Kjaer et al., 2006;Sharma & Maffulli, 2006;Couppe et al., 2008;Magnusson et al., 2010). ...
Article
Full-text available
This study investigated how one bout (1EX) and three bouts (3EX) of strenuous resistance exercise affected the cross-sectional area (CSA) and water content (WC) of the quadriceps muscle and patella tendon (PT), 4 h and 52 h after the last exercise bout. Ten healthy untrained male subjects performed 1EX with one leg and 3EX with the other leg. CSA and WC were measured with magnetic resonance imaging 10, 20 and 30 cm proximal to the tibia plateau (TP) for the muscle, and at the proximal, central and distal site for the PT prior to exercise, and 4 h and 52 h after the last exercise bout. Ten centimeter above the TP, muscle CSA was significantly increased at 4 h (1EX: 13 ± 5%; 3EX: 13 ± 4%) and 52 h (1EX: 16 ± 5%; 3EX: 16 ± 5%) compared with baseline. Muscle WC was significantly increased at 4 h (1EX: 7 ± 1%; 3EX: 6 ± 2%) and 52 h (1EX: 8 ± 2%; 3EX: 8 ± 3%) compared to baseline. PT central CSA was significantly reduced at 52 h (3EX: 14 ± 2%) compared with baseline and (3EX: 13 ± 1%) compared with 4 h. Present data demonstrate that strenuous resistance exercise results in an acute increase in muscle WC and underlines the importance of ensuring sufficient time between the last exercise bout and the determination of anatomical dimensions in muscles.
... One is that most subjects in the study of Herda et al. were not experienced in RE, and it is a common observation that novice lifters tend to respond markedly well to the onset of RE, unlike advanced athletes. This might be because of a decreased MPS signaling in advanced athletes, caused by chronic loading of the muscles (17,41,42,54). It is possible that the beginners in the study by Herda et al. could have benefited from their initial sensitivity to RE, resulting in significant hypertrophy despite suboptimal nutritional circumstances. ...
Article
Full-text available
ABSTRACT: THIS ARTICLE REVIEWS THE AVAILABLE LITERATURE ON WHICH PROTEINS, AMINO ACIDS, OR COMBINATION OF BOTH SEEM TO BE OPTIMAL TO ENHANCE HYPERTROPHY AFTER RESISTANCE EXERCISE IN YOUNG ADULTS. DEPENDING ON THE CONTENT OF ESSENTIAL AMINO ACIDS AND PARTICULARLY LEUCINE, EITHER AN IMMEDIATE INGESTION OF ~20 G MILK PROTEIN FOLLOWED BY A SIMILAR AMOUNT ~1 HOUR LATER, OR A SINGLE BOLUS OF ~40 G SEEMS TO BE SUITABLE. GREATER AMOUNTS MIGHT BE NECESSARY IF A PROTEIN OF LOWER QUALITY IS CHOSEN (I.E., PLANT-BASED PROTEINS) TO MATCH THE REQUIRED AMINO ACID QUANTITIES AND FACILITATE MUSCLE GROWTH.
... However, it should also be noted that high-intensity eccentric exercise gives rise to strong mechanical stress, which may cause some additional effects specific to eccentric actions 69) . Thus, high-intensity eccentric exercise may be useful as a part of periodized training regimens, because performing the same regimen of resistance training is known to cause a gradual decline in the acute changes in signal transduction substrates and MPS after a bout of exercise 51,73,74) , and also in the rate of muscle growth 75,76) . ...
Article
To learn the mechanisms underlying resistance exercise-induced muscle hypertrophy, recent studies on muscle protein metabolism and myogenic progenitor cells were reviewed. Numerous studies have suggested that activation of the translation process plays a major role in a resistance exercise-induced increase in muscle protein synthesis, and also in muscle hypertrophy after a prolonged period of training. Among regulators of the translational activity, the mTORC1 signaling pathway has been shown to be important, although the relation between its upstream regulation and exercise regimen remains unclear. In addition, the muscle satellite cells play a part, even if not indispensable, in exercise-induced muscle hypertrophy, by supplying muscle fibers with new myonuclei. Middle to high exercise intensity has been regarded as essential for gaining muscle mass, because it causes the recruitment of large motor units with fast, type II muscle fibers, which are readily hypertrophied through activation of mTORC1 signaling. However, several studies have shown that low-intensity resistance exercises with either large exercise volume or prolonged contraction time effectively activate protein synthesis and induce muscle hypertrophy. These findings suggest that various strategies are possible in exercise regimens, and exercise intensity is not necessarily a primary factor for gaining muscular size.
... However, this review provides insight that despite not being directly restricted, muscle size and strength of the chest muscles can be increased following low-load BFR training (Table 3). Additionally, as previously mentioned, several studies demonstrated that chest muscle size increased to a greater extent than triceps muscle size following low-load BFR bench press [42,45,47,48] or high-load bench press exercise [53,54]. It would also appear that, despite only the triceps being placed under direct BFR, the relationship of chest to triceps muscle growth at the conclusion of low-load BFR bench press is similar to that seen with high-load bench press [48], albeit to a lesser extent of total muscle growth. ...
Article
Full-text available
Blood flow restriction (BFR) training has been shown to increase muscle size and strength when combined with low-load [20-30 % one-repetition maximum (1RM)] resistance training in the lower body. Fewer studies have examined low-load BFR training in combination with upper body exercise, which may differ as some musculature cannot be directly restricted by the BFR stimulus (chest, shoulders). The objective of this study was to examine muscle adaptations occurring in the upper body in response to low-load BFR training. Google Scholar, PubMed, and SPORTDiscus were searched through July 2015 using the key phrases 'blood flow restriction training', 'occlusion resistance training', and 'KAATSU'. Upper body training studies implementing the BFR stimulus and providing a pre and post measure of muscle size and/or strength were included. A total of 19 articles met the inclusion criteria for this review. The effectiveness of low-load BFR training appears to be minimally impacted by alterations to the intensity and restrictive pressures used; however, the ability to quantitatively analyze our results was limited by unstandardized protocols. Low-load BFR training increased muscle size and strength in limbs located proximal (chest, shoulders) and distal (biceps, triceps) to the restrictive stimulus; while volume-matched exercise in the absence of BFR did not elicit beneficial muscle adaptations. Some of the musculature in the upper body cannot be directly restricted by the application of BFR. Despite this, increases in muscle size and strength were observed in muscles placed under direct and indirect BFR.
... The pectoralis major is one of the main upper-body muscles, the anatomical cross-sectional area (ACSA) of which has been proved to be a key determinant of strength and power during pushing movements (Akagi et al. 2014). To date, most longitudinal (Ogasawara et al. 2011;Ogasawara et al. 2013) and cross-sectional (Akagi et al. 2014) investigations examining pectoralis major ACSA have evaluated this muscular parameter through magnetic resonance imaging (MRI). This technique is considered the gold standard method for measuring muscle mass because of its high agreement with cadaver-measured determinations (Mitsiopoulos et al. 1998). ...
Article
The objective of the current study was to examine the validity and repeatability of panoramic ultrasound in evaluating the anatomical cross-sectional area (ACSA) of the pectoralis major. Specifically, we aimed to quantify the measurement errors generated during the image acquisition and analysis (repeatability), as well as when comparing with magnetic resonance imaging (MRI) (validity). Moreover, we aimed to analyze the influence of the operator's experience on these measurement errors. Both sides of the chest of 16 participants (n = 32) were included. Errors made by two operators (trained and novice) when measuring pectoralis major ACSA (50% of sternum–areola mammae distance) were examined. Acquisition errors included the comparison of two images acquired 5 min apart. Acquisition 1 was analyzed twice to quantify analysis errors. Thereafter, acquisition 1 was compared with MRI. Statistics include the standard error of measurement (SEM), expressed in absolute (cm2) and relative (%) terms as a coefficient of variation (CV), and the calculation of systematic bias. Errors made by the trained operator were lower than those made by the novice, especially during the image acquisition (SEM = 0.25 vs. 0.66 cm2, CV = 1.06 vs. 2.98%) and when compared with MRI (SEM = 0.27 vs. 1.90 cm2, CV = 1.13 vs. 8.16%). Furthermore, although both operators underestimated the ACSA, magnitude and variability [SD] of these errors were lower for the trained operator (bias = –0.19 [0.34] cm2) than for the novice (bias = –1.97 [2.59] cm2). Panoramic ultrasound is a valid and repeatable technique for measuring pectoralis major ACSA, especially when implemented by a trained operator.
... Thus, different RST schemes may be organized as an attempt to avoid detraining effects (e.g. muscle atrophy and strength losses) and to maintain previously acquired training adaptations (Bosquet et al., 2013;Fleck, 1994;Graves et al., 1988;Harris, DeBeliso, Adams, Irmischer, & Spitzer Gibson, 2007;Mujika & Padilla, 2000;Ogasawara, Yasuda, Sakamaki, Ozaki, & Abe, 2011). ...
Article
Full-text available
This study investigated the effects of different reduced strength training (RST) frequencies on half-squat 1 RM and quadriceps cross-sectional area (QCSA). Thirty-three untrained males (24.7±3.9 years; 1.73±0.08m; 74.6±8.4kg) underwent a 16-week experimental period (i.e. eight weeks of strength training [ST] followed by additional eight weeks of RST). During the ST period, the participants performed 3–4 sets of 6–12 RM, three sessions/week in half-squat and knee extension exercises. Following ST, the participants were randomly allocated to one of three groups: reduced strength training with one (RST1) or two sessions per week (RST2), and ceased training (CT). Both RST1 and RST2 groups had their training frequency and total training volume-load (i.e. RST1 = 50.3% and RST2 = 57.1%) reduced, while the CT group stopped training completely. Half-squat 1 RM (RST1=27.9%; RST2=26.7%; and CT=28.4%) and QCSA (RST1 = 6.1%; RST2 = 6.9%; and CT = 5.8%) increased significantly (p < .05) in all groups after eight weeks of ST. No significant changes were observed in 1 RM and QCSA for RST1 and RST2 groups after the RST period, while the CT group demonstrated a decrease in half-squat 1 RM (22.6%) and QCSA (5.4%) when compared to the ST period (p < .05). In conclusion, different RST frequencies applied were able to maintain muscle mass and strength performance obtained over the regular ST period. Thus, it appears that RST frequency does not affect the maintenance of muscle mass and strength in untrained males, as long as volume-load is equated between frequencies. THIS MANUSCRIPT IS PROTECTED BY COPYRIGHT.
... Participants were positioned on the Smith machine equipment (MASTER, Brazil), with the position of the hands on the bar, being standardized as twice the biacromial distance (Ogasawara, Yasuda, Sakamaki, Ozaki, & Abe, 2011). The 1RM test was conducted according to the procedures used in previous studies (Lacerda et al., 2016). ...
Article
This study investigated the impact of 10 weeks performing two equalized resistance training (RT) protocols that differ only by repetition duration and number in the force-position and EMG-position relationship. Participants performed an equalized (36 s of time under tension; 3-4 sets; 3 min between sets; 50-55% of one-repetition maximum; 3x week) RT intervention on the bench press and the only different change between protocols were repetition number (RN; 12vs.6) or duration (RD; 3s vs. 6s). Two experimental groups (RN12RD3, n= 12; and RN6RD6, n=12) performed the RT, while one group was the control (Control, n=11). Maximal isometric contractions at 10%, 50%, and 90% of total bench press range of motion were performed pre- and post-RT, while electromyography was recorded. It was demonstrated an increase in isometric force (+14% to 24%, P<0.001) shifting up the force-position relationship of the training groups after RT, although no difference between training groups compared to Control. Neuromuscular activation from pectoralis major presented an increase after training for both RT groups (+44%; P<0.001) compared to Control. However, although not significantly different, triceps brachii also presented an increase depending on the protocol (+25%). In conclusion, 10 weeks of an equalized RT with longer RN and shorter RD (or opposite) similarly increases the ability to produce maximal isometric force during the bench exercise across different angles, while neuromuscular activation of the pectoralis major partially explained the shift-up of the force-position relationship after training.
... Exercise training is mainly divided into two types. One is resistance exercises like weightlifting or powerlifting that cause skeletal muscle hypertrophy and strength improvements (Ogasawara, Kobayashi, et al., 2013;Ogasawara, Yasuda, Sakamaki, Ozaki, & Abe, 2011). The other is endurance exercises such as long-distance running or cycling that lead to skeletal muscle oxidative and metabolic capacity increase (Fan & Evans, 2017;Holloszy & Coyle, 1984). ...
Article
Full-text available
Concurrent training involves a combination of two different modes of training. In this study, we conducted an experiment by combining resistance and endurance training. The purpose of this study was to investigate the influence of the order of concurrent training on signal molecules in skeletal muscle. The phosphorylation levels of p70 S6 kinase, S6 ribosomal protein, and 4E-binding protein 1, which are related to hypertrophy signaling, increased significantly in the resistance-endurance order group as compared with in control group not the endurance-resistance order group. The gene expressions related to metabolism were not changed by the order of concurrent training. The mitochondrial respiratory chain complex was evaluated by western blot. Although both groups of concurrent training showed a significant increase in MTCO1, UQCRC2, and ATP5A protein levels, we could not detect a difference based on the order of concurrent training. In conclusion, a concurrent training approach involving resistance training before endurance training on the same day is an effective way to activate both mTOR signaling and mitochondria biogenesis.
... In Bezug auf die Maximalkraft konnte gezeigt werden, dass DTR nicht zu einer Reduzierung des 1-RM führte. Dies wurde in verschiedenen Studien mit Erwachsenen[227,229,230,237,244,245], als auch mit 11 bis 15 jährigen Jungen nachgewiesen[254]. Andere Autoren berichteten von Rückgängen der Maximalkraft bei Erwachsenen nach DTR Perioden unterschiedlicher Länge[225,226,228,230], als auch bei Kindern[252,253]. ...
Thesis
Full-text available
Summary of the doctoral thesis Introduction: In many sports, strength is considered an important basis for performance. One factor affecting strength is muscle mass. Therefore, it may be necessary to increase muscle mass in athletes through resistance training. However, the most effective strategy to gain muscle mass has not yet been clearly identified. Many methods used in practice are based on anecdotal evidence rather than empirical data. For this reason, different approaches to hypertrophy training were examined in this thesis based on three studies. The methods and most important results of these studies are summarized in the following. Methods: In the first study, adolescent American football players completed a 12-week resistance training program with three total-body training sessions per week using either Block Periodization (BLOCK) or Daily Undulating Periodization (DUP). The aim was to investigate the effects of the different periodization strategies on muscle mass and athletic performance. The second study assessed the impact of a three-week detraining period (DTR) on anthropometric measures and sport performance. In a third study, highly trained male subjects completed a six-week low-intensity calf resistance training intervention either without (noBFR) or with blood flow restriction (BFR). Before and after the intervention, 1-RM calf raise, calf volume, muscle thickness of the gastrocnemius, and leg stiffness were recorded. Results: At the end of the first intervention, both periodization groups showed significantly higher muscle mass and thickness, as well as athletic performance without differences between groups. Following DTR, fat mass increased significantly, and fat-free mass was reduced. All other measures were unchanged after DTR. Both BFR and NoBFR training resulted in significant increases in 1-RM and muscle thickness without differences between groups. Calf volume and leg stiffness remained unchanged in both conditions. Conclusions: In adolescent American football players, the structure of periodization does not appear to have any effect on muscle growth. Furthermore, a three weeks DTR does not result in negative effects. Both results provide new insights that can be helpful when creating training programs as well as for planning training-free periods. The currently frequently investigated BFR training does not show higher effects on muscle growth of the lower extremities than conventional low-intensity resistance training.
... This detraining period will likely lead to a temporary reduction in training status, performance, and body composition profile. However, once training resumes, these individuals typically regain their body composition adaptations rapidly (47). For example, Zemski et al. (76) reported significant gains in FFM (+1.8 kg) and reductions 48,56). ...
Article
Full-text available
Despite the lack of standardized terminology, building muscle and losing fat concomitantly has been referred to as body recomposition by practitioners. Although many suggest that this only occurs in untrained/novice and overweight/obese populations, there is a substantial amount of literature demonstrating this body recomposition phenomenon in resistance-trained individuals. Moreover, 2 key factors influencing these adaptations are progressive resistance training coupled with evidence-based nutritional strategies. This review examines some of the current literature demonstrating body recomposition in various trained populations, the aforementioned key factors, nontraining/nutrition variables (i.e., sleep, hormones), and potential limitations due to body composition assessments. In addition, this review points out the areas where more research is warranted.
Article
Full-text available
Introducción. El número de estudios relacionados con la fuerza muscular y la funcionalidad invitan al análisis en profundidad de sus resultados antes de su aplicación profesional. Objetivo. Desarrollar una revisión sistemática para la construcción de programas de actividad física centrados en el entrenamiento de fuerza muscular y la capacidad funcional de sedentarios entre los 19 y 79 años. Materiales y métodos. Se emplearon los parámetros PRISMA, Chocrane y de la Universidad de York para el diseño y ejecución de revisiones sistemáticas. Además, se garantizaron criterios de calidad y especificidad estrictos que permitieron identificar 14 categorías de análisis, de las cuales emergieron las pautas de programación que se informan en la revisión sistemática. Resultados. 49 estudios con nivel de evidencia 1+ (24%), 1- (33%), 2++ (4%), 2+ (29%) y 2- (10%) cumplieron con los criterios de selección establecidos y permitieron alimentar las 14 categorías propuestas y hacer una síntesis de contenido. Conclusión. Es posible elevar el efecto de los programas de actividad física sobre la fuerza muscular y la funcionalidad a partir de la identificación y consideración de unas variables de programación (categoría) básicas que se sustentan en la calidad de evidencia científica circulante.
Preprint
Full-text available
Background: Good physical health and capacity is a requirement for offshore wind service technicians (WTs) who have substantial physical work demands and are exposed to numerous health hazards. Workplace physical exercise has shown promising results as a strategy for maintaining and improving physical health and work ability among various types of workers. Therefore, we aimed to assess the feasibility and preliminary efficacy of the Intelligent Physical Exercise Training (IPET) concept among WTs in the offshore wind industry. Methods: The present study used a within-subject design to assess the feasibility and preliminary efficacy of IPET (one hour/week individualized exercise during working hours). The intervention period was 12 weeks, with the first eight weeks performed on site as supervised or partly supervised exercise during work hours and the last four weeks planned as home-administered exercise after termination of the seasonal offshore service period. Three assessments, T1 (six months prior to intervention start), T2 (start of intervention) and T3 (end of intervention), of physical health and capacity (self-reported and objective measurements) were conducted and the period between T1 and T2 served as a within-subject control period. Primary outcome was feasibility measured as compliance, adherence, adverse events, and participant acceptability. Descriptive statistics were used to present feasibility outcomes and pairwise comparisons were performed to assess for differences in outcomes between T1, T2 and T3. Results: All WTs at the included wind farm (n=24, age: 40 years (SD±8)) participated in the study. No serious adverse events were reported. Compliance and adherence of 95 and 80% respectively, were reached in the eight-week supervised part, but lower when exercise was home-administered (<20%). Acceptability was high for the supervised part, with 83% indicating that the exercise program worked well and 100% that exercise should be implemented as an integrated part of the working structure. Physical capacity and health parameters collected at T1, T2 and T3 increased before and during the intervention period, indicating seasonal fluctuations in addition to possible improvements caused by the intervention. Conclusion: Implementation of Intelligent Physical Exercise Training on site and during working hours seems to be feasible and well received among WTs in the offshore wind industry. Trial registration: ClinicalTrials.gov (Identifier: NCT04995718). Retrospectively registered on August 6, 2021, https://clinicaltrials.gov/ct2/show/NCT04995718?term=NCT04995718&draw=2&rank=1
Article
Background: Respiratory muscle weakness is a primary cause of morbidity and mortality in patients with Pompe disease. We previously described the effects of our 12-week respiratory muscle training (RMT) regimen in 8 adults with late-onset Pompe disease [1] and 2 children with infantile-onset Pompe disease [2]. Case report: Here we describe repeat enrollment by one of the pediatric participants who completed a second 12-week RMT regimen after 7 months of detraining. We investigated the effects of two 12-week RMT regimens (RMT #1, RMT #2) using a single-participant A-B-A experimental design. Primary outcome measures were maximum inspiratory pressure (MIP) and maximum expiratory pressure (MEP). Effect sizes for changes in MIP and MEP were determined using Cohen's d statistic. Exploratory outcomes targeted motor function. Relevance: From pretest to posttest, RMT #2 was associated with a 25% increase in MIP and a 22% increase in MEP, corresponding with very large effect sizes (d= 2.92 and d=A 2.65, respectively). Following two 12-week RMT regimens over 16 months, MIP increased by 69% and MEP increased by 97%, corresponding with very large effect sizes (d= 3.57 and d= 5.10, respectively). MIP and MEP were largely stable over 7 months of detraining between regimens. Magnitude of change was greater for RMT #1 relative to RMT #2.
Article
Kubo, K, Ikebukuro, T, and Yata, H. Effects of 4, 8, and 12 repetition maximum resistance training protocols on muscle volume and strength. J Strength Cond Res XX(X): 000-000, 2020-The purpose of this study was to determine skeletal muscle adaptations (strength and hypertrophy) in response to volume-equated resistance training with divergent repetition strategies. Forty-two men were randomly assigned to 4 groups: higher load-lower repetition group performing 4 repetition maximum (RM) for 7 sets (4RM, n = 10), intermediate load-intermediate repetition group performing 8RM for 4 sets (8RM, n = 12), lower load-higher repetition group performing 12RM for 3 sets (12RM, n = 10), and nonexercising control group (CON, n = 10). The volume of the pectoralis major muscle (by magnetic resonance imaging) and 1RM of the bench press were measured before and after 10 weeks of training (2 times per week). No significant difference was observed in the relative increase in the muscle volume among the 4RM, 8RM, and 12RM groups. The relative increase in 1RM was significantly lower in the 12RM group than in the 4RM group (p = 0.029) and the 8RM group (p = 0.021). The relative increase in 1RM was significantly correlated with that in the muscle volume in the 12RM group (r = 0.684, p = 0.042), but not in the 4RM (r = -0.265, p = 0.777) or 8RM (r = -0.045, p = 0.889) groups. These results suggest that the increase in muscle size is similar among the 3 training protocols when the training volume was equated, whereas the increase in muscle strength is lower with the 12RM protocol than the other protocols.
Article
The aim of this study was to analyze the validity of anthropometric equations to identify changes in skeletal muscle mass (SMM) after resistance training (RT). Anthropometric and dual energy x-ray absorptiometry (DXA) measurements were obtained at baseline and after RT in 15 trained Caucasian college men. Participants performed RT over 8 weeks, consisting of 8-9 exercises of 4 sets with 12/10/8/6 maximal repetitions and 1-2 min interval between sets. The training loads were gradually increased according to gains in muscular strength. 4 anthropometric equations were used for estimation of SMM: EQ1 (SMM, g=height×[0.0553×corrected thigh girth2 + 0.0987×forearm girth2 + 0.0331×corrected calf girth2] - 2445), EQ2 (SMM, g=height×[0.031×medial thigh girth2 + 0.064×corrected calf girth2 + 0.089×corrected arm girth2] - 3006), EQ3 (SMM, kg=height×[0.00744×corrected arm girth2 + 0.00088×corrected thigh girth2 + 0.00441×corrected calf girth2] + 2.4×gender - 0.048×age + race + 7.8) and EQ4 (SMM, kg=0.244×weight + 7.8×height + 6.6×gender - 0.098×age + race - 3.3). EQ1 and EQ2 overestimated the SMM (41.3% and 19.9%, respectively; P<0.05) while EQ3 and EQ4 were similar (P>0.05) to DXA at baseline. Although all equations and DXA revealed a significant increase in SMM after RT, changes were overestimated by EQ1 and EQ2 (P<0.05), but not by EQ3 and EQ4 (P>0.05). In addition, changes in SMM over time between EQ4 and DXA were significantly correlated (r=0.62; P<0.01). Thus, changes in SMM that occur after RT can be detected by EQ4 in trained young men.
Article
The present study investigated whether whole-body vibration (WBV) coupled with low-velocity exercise (EX) for 13 weeks retains muscle performance gains after 5 weeks of subsequent detraining compared with the identical EX program without WBV. Thirty-two untrained healthy adults (22-49 years of age) were randomly assigned to groups that performed EX with or without WBV (EX-WBV and EX, respectively; n=16 per group). The following outcome variables were evaluated: countermovement jump height; maximal isometric, concentric, and eccentric knee extension strengths; local muscular endurance; and lumbar extension torque before, during, and after the 13-week training period, and after 5 weeks of detraining. Compared to the EX group, significantly higher increases in countermovement jump height and isometric and concentric knee extension strengths were detected in the EX-WBV group after the 13-week training period. However, detraining caused significant declines in these three muscle performance tests only in the EX-WBV group (-4.8% , -10.2%, and -17.2%, respectively), resulting in no significant differences between the test and control groups after the detraining period. After detraining, all examined variables showed significantly better performance compared to pre-training (P<0.05) and did not significantly differ from mid-training (seven weeks) in both groups (P>0.05). These results suggest that muscle strength in the lower extremities, particularly isometric and concentric contractions, and muscle power might be more susceptible to short-term detraining effects when exercise is combined with WBV. Thus, it is necessary to perform regular exercise to maximize the benefits of WBV on muscle strength and power during the early stages of training in previously untrained individuals.
Article
Full-text available
Chronic resistance training induces increases in muscle fibre cross-sectional area (CSA) otherwise known as hypertrophy. This is due to an increased volume percentage of myofibrillar proteins within a given fibre. The exact time-course for muscle fibre hypertrophy is not well-documented but appears to require at least 6-7 weeks of regular resistive training at reasonably high intensity before increases in fibre CSA are deemed significant. Proposed training-induced changes in neural drive are hypothesized to increase strength due to increased synchrony of motor unit firing, reduced antagonist muscle activity, and/or a reduction in any bilateral strength deficit. Nonetheless, increases in muscle protein synthesis were observed following an isolated bout of resistance exercise. In addition, muscle balance was positive, following resistance exercise when amino acids were infused/ingested. This showed that protein accretion occurred during the postexercise period. The implications of this hypothesis for training-induced increases in strength are discussed.
Article
Full-text available
Skeletal muscle hypertrophy is typically considered to be a slow process. However, this is partly because the time course for hypertrophy has not been thoroughly examined. The purpose of this study was to use weekly testing to determine a precise time course of skeletal muscle hypertrophy during a resistance training program. Twenty-five healthy, sedentary men performed 8 weeks of high-intensity resistance training. Whole muscle cross-sectional area (CSA) of the dominant thigh was assessed using a peripheral quantitative computed tomography scanner during each week of training (W1-W8). Isometric maximum voluntary contractions (MVC) were also measured each week. After only two training sessions (W1), the mean thigh muscle CSA increased by 5.0 cm(2) (3.46%; p < 0.05) from the pre-testing (P1) and continued to increase with each testing session. It is possible that muscular edema may have influenced the early CSA results. To adjust for this possibility, with edema assumedly at its highest at W1, the next significant increase from W1 was at W3. W4 was the first significant increase of MVC over P1. Therefore, significant skeletal muscle hypertrophy likely occurred around weeks 3-4. Overall, from the pre-testing to W8, there was an increase of 13.9 cm(2) (9.60%). These findings suggested that training-induced skeletal muscle hypertrophy may occur early in a training program.
Article
Full-text available
Effects of previous strength training can be long-lived, even after prolonged subsequent inactivity, and retraining is facilitated by a previous training episode. Traditionally, such "muscle memory" has been attributed to neural factors in the absence of any identified local memory mechanism in the muscle tissue. We have used in vivo imaging techniques to study live myonuclei belonging to distinct muscle fibers and observe that new myonuclei are added before any major increase in size during overload. The old and newly acquired nuclei are retained during severe atrophy caused by subsequent denervation lasting for a considerable period of the animal's lifespan. The myonuclei seem to be protected from the high apoptotic activity found in inactive muscle tissue. A hypertrophy episode leading to a lasting elevated number of myonuclei retarded disuse atrophy, and the nuclei could serve as a cell biological substrate for such memory. Because the ability to create myonuclei is impaired in the elderly, individuals may benefit from strength training at an early age, and because anabolic steroids facilitate more myonuclei, nuclear permanency may also have implications for exclusion periods after a doping offense.
Article
Full-text available
Aging skeletal muscle is characterized not only by a reduction in size (sarcopenia) and strength but also by an increase in fatty infiltration (myosteatosis). An effective countermeasure to sarcopenia is resistance exercise; however, its effect on fatty infiltration is less clear. To examine in resistance-trained older persons whether muscle attenuation, a noninvasive measure of muscle density reflecting intramuscular lipid content, is altered with training status. Thirteen healthy community-dwelling men and women aged 65-83 years (body mass index 27.0+/-1.2, mean+/-SE) had computed-tomography scans of the mid-thigh performed following 24 weeks of training, 24 weeks of detraining, and 12 weeks of retraining. Training and retraining were undertaken twice weekly for several upper- and lower-body muscle groups. Skeletal muscle attenuation in Hounsfield units (HU) as well as mid-thigh muscle volume was obtained for the quadriceps and hamstrings. Muscle strength was assessed by 1-repetition maximum and physical function by a battery of tests. The average change in muscle strength following training, detraining and retraining was 48.8+/-2.9%, -17.6+/-1.3%, and 19.8+/-2.0%, respectively. Strength changes were accompanied by significant alterations in muscle density (p<0.001), with the quadriceps HU decreasing by 7.7+/-1.0% following detraining and increasing by 5.4+/-0.5% with retraining. For the hamstrings HU measure, detraining and retraining resulted in an 11.9+/-1.4% loss and a 5.5+/-1.8% gain, respectively. There was no significant change in muscle volume. Cessation of resistance exercise in trained older persons increases the fatty infiltration of muscle, while resumption of exercise decreases it. Monitoring changes in both muscle size and fat infiltration may enable a more comprehensive assessment of exercise in combating age-related muscular changes.
Article
Full-text available
Muscle contraction during exercise, whether resistive or endurance in nature, has profound affects on muscle protein turnover that can persist for up to 72 h. It is well established that feeding during the postexercise period is required to bring about a positive net protein balance (muscle protein synthesis - muscle protein breakdown). There is mounting evidence that the timing of ingestion and the protein source during recovery independently regulate the protein synthetic response and influence the extent of muscle hypertrophy. Minor differences in muscle protein turnover appear to exist in young men and women; however, with aging there may be more substantial sex-based differences in response to both feeding and resistance exercise. The recognition of anabolic signaling pathways and molecules are also enhancing our understanding of the regulation of protein turnover following exercise perturbations. In this review we summarize the current understanding of muscle protein turnover in response to exercise and feeding and highlight potential sex-based dimorphisms. Furthermore, we examine the underlying anabolic signaling pathways and molecules that regulate these processes.
Article
Full-text available
Six women who had participated in a previous 20-wk strength training study for the lower limb detrained for 30-32 wk and subsequently retrained for 6 wk. Seven untrained women also participated in the 6-wk "retraining" phase. In addition, four women from each group volunteered to continue training an additional 7 wk. The initial 20-wk training program caused an increase in maximal dynamic strength, hypertrophy of all three major fiber types, and a decrease in the percentage of type IIb fibers. Detraining had relatively little effect on fiber cross-sectional area but resulted in an increased percentage of type IIb fibers with a concomitant decrease in IIa fibers. Maximal dynamic strength decreased but not to pretraining levels. Retraining for 6 wk resulted in significant increases in the cross-sectional areas of both fast fiber types (IIa and IIab + IIb) compared with detraining values and a decrease in the percentage of type IIb fibers. The 7-wk extension accentuated these trends such that cross-sectional areas continued to increase (nonsignificant) and no IIb fibers could be found. Similar results were found for the nonpreviously trained women. These data suggest that rapid muscular adaptations occur as a result of strength training in previously trained as well as non-previously trained women. Some adaptations (fiber area and maximal dynamic strength) may be retained for long periods during detraining and may contribute to a rapid return to "competitive" form.
Article
Full-text available
Chronic resistance training induces increases in muscle fibre cross-sectional area (CSA), otherwise known as hypertrophy. This is due to an increased volume percentage of myofibrillarproteins within a given fibre. The exact time-course for muscle fibre hypertrophy is not well-documented but appears to require at least 6-7 weeks of regular resistive training at reasonably high intensity before increases in fibre CSA are deemed significant. Proposed training-induced changes in neural drive are hypothesized to increase strength due to increased synchrony of motor unit firing, reducedant agonist muscle activity, and/or a reduction in any bilateral strength deficit. Nonetheless, increases in muscle protein synthesis were observed following an isolated bout of resistance exercise. In addition, muscle balance was positive, following resistance exercise when amino acids were infused/ingested. This showed that protein accretion occurred during the postexercise period. The implications of this hypothesis for training-induced increases in strength are discussed.
Article
Full-text available
The object of this study was to examine changes in muscular strength, power, and resting hormonal concentrations during 6 weeks of detraining (DTR) in recreationally strength-trained men. Each subject was randomly assigned to either a DTR (n = 9) or resistance training (RT; n = 7) group after being matched for strength, body size, and training experience. Muscular strength and power testing, anthropometry, and blood sampling were performed before the experimental period (T1), after 3 weeks (T2), and after the 6-week experimental period (T3). One-repetition maximum (1RM) shoulder and bench press increased in RT at T3 (p </= 0.05), whereas no significant changes were observed in DTR. Peak power output and mean power output significantly decreased (9 and 10%) in DTR at T2. Peak torque of the elbow flexors at 90 degrees did not change in the RT group but did significantly decrease by 11.9% at T3 compared with T1 in the DTR group. Vertical jump height increased in RT at T2 but did not change in DTR. Neither group displayed any changes in 1RM squat, body mass, percent body fat, or resting concentrations of growth hormone, follicle-stimulating hormone, luteinizing hormone, sex hormone-binding globulin, testosterone, cortisol, or adrenocorticotropin. These data demonstrate that 6 weeks of resistance DTR in recreationally trained men affects power more than it does strength without any accompanying changes in resting hormonal concentrations. For the recreational weight trainer, losses in strength over 6 weeks are less of a concern compared with anaerobic power and upper arm isometric force production. Anaerobic power exercise with a high metabolic component coming from glycolysis might be of importance for reducing the impact of DTR on Wingate power performances. A minimal maintenance training program is recommended for the recreational lifter to offset any reductions in performance.
Article
Full-text available
The onset of whole muscle hypertrophy in response to overloading is poorly documented. The purpose of this study was to assess the early changes in muscle size and architecture during a 35-day high-intensity resistance training (RT) program. Seven young healthy volunteers performed bilateral leg extension three times per week on a gravity-independent flywheel ergometer. Cross-sectional area (CSA) in the central (C) and distal (D) regions of the quadriceps femoris (QF), muscle architecture, maximal voluntary contraction (MVC), and electromyographic (EMG) activity were measured before and after 10, 20, and 35 days of RT. By the end of the training period, MVC and EMG activity increased by 38.9 +/- 5.7 and 34.8% +/- 4.7%, respectively. Significant increase in QF CSA (3.5 and 5.2% in the C and D regions, respectively) was observed after 20 days of training, along with a 2.4 +/- 0.7% increase in fascicle length from the 10th day of training. By the end of the 35-day training period, the total increase in QF CSA for regions C and D was 6.5 +/- 1.1 and 7.4 +/- 0.8%, respectively, and fascicle length and pennation angle increased by 9.9 +/- 1.2 and 7.7 +/- 1.3%, respectively. The results show for the first time that changes in muscle size are detectable after only 3 wk of RT and that remodeling of muscle architecture precedes gains in muscle CSA. Muscle hypertrophy seems to contribute to strength gains earlier than previously reported; flywheel training seems particularly effective for inducing these early structural adaptations.
Article
Full-text available
Strength training is an important component in sports training and rehabilitation. Quantification of the dose-response relationships between training variables and the outcome is fundamental for the proper prescription of resistance training. The purpose of this comprehensive review was to identify dose-response relationships for the development of muscle hypertrophy by calculating the magnitudes and rates of increases in muscle cross-sectional area induced by varying levels of frequency, intensity and volume, as well as by different modes of strength training. Computer searches in the databases MEDLINE, SportDiscus® and CJNAHL® were performed as well as hand searches of relevant journals, books and reference lists. The analysis was limited to the quadriceps femoris and the elbow flexors, since these were the only muscle groups that allowed for evaluations of dose-response trends. The modes of strength training were classified as dynamic external resistance (including free weights and weight machines), accommodating resistance (e.g. isokinetic and semi-isokinetic devices) and isometric resistance. The subcategories related to the types of muscle actions used. The results demonstrate that given sufficient frequency, intensity and volume of work, all three types of muscle actions can induce significant hypertrophy at an impressive rate and that, at present, there is insufficient evidence for the superiority of any mode and/or type of muscle action over other modes and types of training. Tentative dose-response relationships for each variable are outlined, based on the available evidence, and interactions between variables are discussed. In addition, recommendations for training and suggestions for further research are given.
Article
Full-text available
Ten healthy young men (21.0 +/- 1.5 yr, 1.79 +/- 0.1 m, 82.7 +/- 14.7 kg, means +/- SD) participated in 8 wk of intense unilateral resistance training (knee extension exercise) such that one leg was trained (T) and the other acted as an untrained (UT) control. After the 8 wk of unilateral training, infusions of L-[ring-d(5)]phenylalanine, L-[ring-(13)C(6)]phenylalanine, and d(3)-alpha-ketoisocaproic acid were used to measure mixed muscle protein synthesis in the T and UT legs by the direct incorporation method [fractional synthetic rate (FSR)]. Protein synthesis was determined at rest as well as 4 h and 28 h after an acute bout of resistance exercise performed at the same intensity relative to the gain in single repetition maximum before and after training. Training increased mean muscle fiber cross-sectional area only in the T leg (type I: 16 +/- 10%; type II: 20 +/- 19%, P < 0.05). Acute resistance exercise increased muscle protein FSR in both legs at 4 h (T: 162 +/- 76%; UT: 108 +/- 62%, P < 0.01 vs. rest) with the increase in the T leg being significantly higher than in the UT leg at this time (P < 0.01). At 28 h postexercise, FSR in the T leg had returned to resting levels; however, the rate of protein synthesis in the UT leg remained elevated above resting (70 +/- 49%, P < 0.01). We conclude that resistance training attenuates the protein synthetic response to acute resistance exercise, despite higher initial increases in FSR, by shortening the duration for which protein synthesis is elevated.
Article
If limitations exist in skeletal dimensions, fat-free mass (FFM) might have an upper limit. To explore the upper limit to FFM, 37 professional Japanese Sumo wrestlers, 14 highly trained bodybuilders, and 26 untrained men were investigated for body composition (fat mass and FFM) and cross-sectional areas (CSA) of limb muscles, by hydrodensitometry and ultrasound, respectively. Mean % fat of Sumo wrestlers, bodybuilders, and untrained subjects were, respectively, 26.1%, 10.9%, and 12.1%. Sumo wrestlers had a significantly greater FFM than bodybuilders, who had a greater FFM than the untrained men. Six of the wrestlers had more than 100 kg of FFM, including the largest one of 121.3 kg (stature: 186 cm, mass: 181 kg, %fat: 33.0%). The FFM/stature ratio of elite Sumo wrestlers averaged at 0.61 kg/cm, with the highest 0.66 kg/cm. It is suggested that a FFM/stature ratio of 0.7 kg/cm may be an upper limit in humans. © 1994 Wiley-Liss, Inc.
Article
The purpose of this study was to investigate the time course of changes in mechanical and morphological properties of muscle and tendon during isometric training and detraining. Eight subjects completed 3 months of isometric knee extension training and detraining for another 3 months. At beginning and on every 1 month of training and detraining periods, muscle strength, neural activation level, muscle and tendon cross-sectional areas (CSA), and tendon stiffness were measured. Training increased muscle strength and neural activation level by 29.6 and 7.3% after 2 months and by 40.5 and 8.9% after 3 months (all p's < 0.05). Muscle CSA and tendon stiffness did not change until 2 months of training period, and afterward, the increases in muscle CSA and tendon stiffness reached statistical significance at the end of training period (both p's < 0.05). During detraining period, muscle strength and neural activation level did not change, although muscle CSA and tendon stiffness decreased to pre-training level at 1 and 2 months of detraining, respectively. These results suggest that the adaptations of tendon properties and muscle morphology to resistance training are slower than those of muscle function and inversely that the adaptations of former to detraining are faster than those of latter.
Article
Training cessation among older adults is associated with the loss of functional ability. However, exercise programs undertaken prior to activity cessation may offer functional protection. In the present study, the residual effects of muscle power or muscle strength training were investigated following extended detraining and subsequent retraining. Thirty-eight healthy independent older adults (65-84 years) entered a 24-week detraining period subsequent to 24 weeks of training. Following detraining, participants recommenced training using either the high-velocity muscle power (HV) or muscle strength (ST) protocol, as undertaken during the initial training period, twice weekly for 12 weeks. Isometric and dynamic muscle strength, muscle power, movement velocity, muscle endurance, electromyographic activity, and the results of a battery of functional performance tasks were assessed. Muscle function and functional performance increased following initial training, however, no group differences were observed. Detraining resulted in similar declines in muscle power and muscle strength for both groups (p <.05) (power, HV 17.8 +/- 1.8%, ST 15.5 +/- 2.2%; and strength, HV 17.1 +/- 2.2%, ST 16.5 +/- 1.8%), with comparable accrual following retraining. No significant changes in functional ability were observed following detraining (average change; HV 3.1 +/- 3.5% and ST 2.1 +/- 3.5%) or retraining. No group differences emerged in this study. Cessation of training resulted in only a modest loss of muscle power and strength that was recouped following 12 weeks of retraining. Importantly, training-induced gains in functional performance were preserved during detraining. The residual effects of power or strength training appear comparable, and both may be suitable exercise modes prior to a period of activity cessation to promote physical independence.
Article
Three different training regimens were performed to study the influence of eccentric muscle actions on skeletal muscle adaptive responses to heavy resistance exercise. Middle-aged males performed the leg press and leg extension exercises two days each week. The resistance was selected to induce failure within six to twelve repetitions of each set. Group CON/ECC (n = 8) performed coupled concentric and eccentric actions while group CON (n = 8) used concentric actions only. They did four or five sets of each exercise. Group CON/CON (n = 10) performed twice as many sets with only concentric actions. Eight subjects did not train and served as controls. Tissue samples were obtained from m. vastus lateralis using the biopsy technique before and after 19 weeks of training, and after four weeks of detraining. Histochemical analyses were performed to assess fibre type composition, fibre area and capillarization. Training increased (P less than 0.05) Type IIA and decreased (P less than 0.05) Type IIB fibre percentage. Only group CON/ECC increased Type I area (14%, P less than 0.05). Type II area increased (P less than 0.05) 32 and 27%, respectively, in groups CON/ECC and CON/CON, but not in group CON. Mean fibre area increased (P less than 0.05) 25 and 20% in groups CON/ECC and CON/CON, respectively. Capillaries per fibre increased (P less than 0.05) equally for Type I and Type II fibres. Capillaries per fibre area for both fibre types, however, increased (P less than 0.05) only in groups CON and CON/CON. The changes in fibre type composition and capillary frequency were manifest after detraining.(ABSTRACT TRUNCATED AT 250 WORDS)
Article
Strength performance depends not only on the quantity and quality of the involved muscles, but also upon the ability of the nervous system to appropriately activate the muscles. Strength training may cause adaptive changes within the nervous system that allow a trainee to more fully activate prime movers in specific movements and to better coordinate the activation of all relevant muscles, thereby effecting a greater net force in the intended direction of movement. The evidence indicating neural adaptation is reviewed. Electromyographic studies have provided the most direct evidence. They have shown that increases in peak force and rate of force development are associated with increased activation of prime mover muscles. Possible reflex adaptations related to high stretch loads in jumping and rapid reciprocal movements have also been revealed. Other studies, including those that demonstrate the "cross-training" effect and specificity of training, provide further evidence of neural adaptation. The possible mechanisms of neural adaptation are discussed in relation to motor unit recruitment and firing patterns. The relative roles of neural and muscular adaptation in short- and long-term strength training are evaluated.
Article
Summary The training effect on the human arm flexor was studied by subjecting 5 healthy males. The training was made by isometric maximum contraction, 3 times (10 seconds/bout) a day, every day except Sunday for 100 days. Ultrasonic photography was employed to estimate the cross-sectional area of the muscle.1. The muscle training of 100 days increased the maximum strength by 91.7% and the cross-sectional area of muscle by 23.0%. 2. The average values of strength per unit cross-sectional area of muscle increased from 6.3 to 10.0 kg/cm2 after 100th day of training at extended position of arm, from 4.7 to 7.5 kg/cm2 at flexed position of arm. 3. The increase of maximum strength was associated with the increase in cross-sectional area and the increase in strength per unit cross-sectional area.
Article
To study the effects of resistance training on muscle strength and size in older people, we enrolled 8 men and 17 women (mean age 68.2 +/- 1 SEM) into a one-year exercise trial. Subjects were randomly assigned to exercise or control groups. Muscle biopsies were obtained from 11 subjects (8 exercisers/3 controls) at baseline and after 15 weeks; exercisers underwent another biopsy at 30 weeks. After testing maximum strength using the 1-RM method, the exercisers began a 12-exercise circuit (3 sets of 8 repetitions at 75% of 1-RM), 3 times a week. The controls repeated the strength testing every 15 weeks. They were asked to continue usual activities and not to start any exercise program. With exercise, muscle strength increased, average increases ranging from 30% (hip extensors) to 97% (hip flexors). Strength increased rapidly over 3 months, then plateaued for the duration of the experiment. No strength changes were observed in sedentary controls. Cross-sectional area of type 1 muscle fibers increased in exercisers by 15 weeks (29.4 +/- 1%, p < .02) and after 30 weeks (58.5 +/- 13.7%, p < .002) compared to baseline. Type 2 fiber area did not change at 15 weeks, but increased by 30 weeks of training (66.6 +/- 9.5%, p < .0002). These results suggest that prolonged moderate to high intensity resistance training may be carried out by healthy older adults with reasonable compliance, and that such training leads to sustained increases in muscle strength. These improvements are rapidly achieved and are accompanied by hypertrophy of both type 1 and type 2 muscle fibers.
Article
We investigated the effects of 14 d of resistive exercise detraining on 12 power athletes. In comparing performances pre- to post-detraining, there were no significant (P > 0.05) changes in free weight bench press (-1.7%), parallel squat (-0.9%), isometric (-7%) and isokinetic concentric knee extension force (-2.3%), and vertical jumping (1.2%). In contrast, isokinetic eccentric knee extension force decreased in every subject (-12%, P < 0.05). Post-detraining, the changes in surface EMG activity of the vastus lateralis during isometric, and isokinetic eccentric and concentric knee extension were -8.4%, -10.1%, and -12.7%, respectively (all P > 0.05). No significant changes occurred in knee flexion forces or EMGs (P > 0.05). Percentages of muscle fiber types and the Type I fiber area remained unchanged, but Type II fiber area decreased significantly by -6.4% (P < 0.05). Levels of plasma growth hormone (58.3%), testosterone (19.2%), and the testosterone to cortisol ratio (67.6%) increased, whereas plasma cortisol (-21.5%) and creatine kinase enzyme levels (-82.3%) decreased (all P < 0.05). Short-term resistive exercise detraining may thus specifically affect eccentric strength or the size of the Type II muscle fibers, leaving other aspects of neuromuscular performance uninfluenced. Changes in the hormonal milieu during detraining may be conducive to an enhanced anabolic process, but such changes may not materialize at the tissue level in the absence of the overload training stimulus.
Article
To investigate the effects of cessation and subsequent resumption of training on muscle strength in elderly men, 11 men (aged 65-77 years), just completing a 24-week randomized controlled trial of recombinant human growth hormone (rhGH) and resistance exercise (rhGH, n = 6; placebo, n = 5), detrained for 12 weeks and subsequently retrained for 8 weeks. During the detraining and retraining phase, subjects did not receive rhGH. The resistance programme included three sets of eight repetitions at 75% of one-repetition maximum (1-RM), three times per week, for 10 upper and lower body exercises. Dynamic muscle strength was assessed by the 1-RM method every 2 weeks for 44 weeks. Needle biopsies of vastus lateralis muscle were obtained from seven men. Muscle strength increased during initial training by 40.4 +/- 5.5% (mean +/- SEM), ranging from 26.0 +/- 5.0 to 83.9 +/- 15.6%, depending on muscle group. Increased strength was accompanied by hypertrophy (P < 0.05) of type I (17.4 +/- 4.1%) and II (25.8 +/- 12.4%) muscle fibres. Of initial strength gains, only 29.9 +/- 5.2% was lost with detraining. However, type I and II fibre cross-sectional area reverted to pretraining values. After 8 weeks of retraining, muscle strength returned to trained values, but without a significant change in fibre morphology. The results indicate that elderly men lose some muscle strength following short-term detraining, but that only a brief period of retraining suffices to regain maximal strength. Reversal of fibre cross-sectional area with detraining, and only modest improvement with retraining, suggests that much of the retention in strength with detraining and reacquisition of lost strength with retraining reflects neural adaptation.
Article
The purpose of this study was to investigate the time course of skeletal muscle adaptations resulting from high-intensity, upper and lower body dynamic resistance training (WT). A group of 17 men and 20 women were recruited for WT, and 6 men and 7 women served as a control group. The WT group performed six dynamic resistance exercises to fatigue using 8-12 repetition maximum (RM). The subjects trained 3 days a week for 12 weeks. One-RM knee extension (KE) and chest press (CP) exercises were measured at baseline and at weeks 2, 4, 6, 8, and 12 for the WT group. Muscle thickness (MTH) was measured by ultrasound at eight anatomical sites. One-RM CP and KE strength had increased significantly at week 4 for the female WT group. For the men in the WT group, 1 RM had increased significantly at week 2 for KE and at week 6 for CP. The mean relative increases in KE and CP strength were 19% and 19% for the men and 19% and 27% for the women, respectively, after 12 weeks of WT. Resistance training elicited a significant increase in MTH of the chest and triceps muscles at week 6 in both sexes. There were non-significant trends for increases in quadriceps MTH for the WT groups. The relative increases in upper and lower body MTH were 12%-21% and 7%-9% in the men and 10%-31% and 7%-8% in the women respectively, after 12 weeks of WT. These results would suggest that increases in MTH in the upper body are greater and occur earlier compared to the lower extremity, during the first 12 weeks of a total body WT programme. The time-course and proportions of the increase in strength and MTH were similar for both the men and the women.
Article
Resistance training has been shown to considerably increase strength and neural drive during maximal eccentric muscle contraction; however, less is known about the adaptive change induced by subsequent detraining. The purpose of the study was to examine the effect of dynamic resistance training followed by detraining on changes in maximal eccentric and concentric isokinetic muscle strength, as well as to examine the corresponding adaptations in muscle cross-sectional area (CSA) and EMG activity. Maximal concentric and eccentric isokinetic knee extensor moment of force was measured in 13 young sedentary males (age 23.5±3.2 years), before and after 3 months of heavy resistance training and again after 3 months of detraining. Following training, moment of force increased during slow eccentric (50%, P<0.001), fast eccentric (25%, P<0.01), slow concentric (19%, P<0.001) and fast concentric contraction (11%, P<0.05). Corresponding increases in EMG were observed during eccentric and slow concentric contraction. Significant correlations were observed between the training-induced changes in moment of force and EMG (R 2=0.33–0.77). Muscle CSA (measured by MRI) increased by 10% (P<0.001). After 3 months of detraining maximal muscle strength and EMG remained preserved during eccentric contraction but not concentric contraction. The present findings suggest that heavy resistance training induces long-lasting strength gains and neural adaptations during maximal eccentric muscle contraction in previously untrained subjects.
Article
Skeletal muscle size is tightly regulated by the synergy between anabolic and catabolic signalling pathways which, in humans, have not been well characterized. Akt has been suggested to play a pivotal role in the regulation of skeletal muscle hypertrophy and atrophy in rodents and cells. Here we measured the amount of phospho-Akt and several of its downstream anabolic targets (glycogen synthase kinase-3beta (GSK-3beta), mTOR, p70(s6k) and 4E-BP1) and catabolic targets (Foxo1, Foxo3, atrogin-1 and MuRF1). All measurements were performed in human quadriceps muscle biopsies taken after 8 weeks of both hypertrophy-stimulating resistance training and atrophy-stimulating de-training. Following resistance training a muscle hypertrophy ( approximately 10%) and an increase in phospho-Akt, phospho-GSK-3beta and phospho-mTOR protein content were observed. This was paralleled by a decrease in Foxo1 nuclear protein content. Following the de-training period a muscle atrophy (5%), relative to the post-training muscle size, a decrease in phospho-Akt and GSK-3beta and an increase in Foxo1 were observed. Atrogin-1 and MuRF1 increased after the hypertrophy and decreased after the atrophy phases. We demonstrate, for the first time in human skeletal muscle, that the regulation of Akt and its downstream signalling pathways GSK-3beta, mTOR and Foxo1 are associated with both the skeletal muscle hypertrophy and atrophy processes.
Influence of eccentric actions on skeletal muscle adaptations to resistance training Detraining and retraining in older adults following long-term muscle power or muscle strength spe-cific training The effects of detraining on power athletes
  • Tr Henwood
  • Taaffe
  • T Hortobagyi
  • Ja Houmard
  • Jr Stevenson
  • Dd Fraser
  • Ra Johns
  • Israel
Influence of eccentric actions on skeletal muscle adaptations to resistance training. Acta Physiol Scand (1991); 143: 177–185. Henwood TR, Taaffe DR. Detraining and retraining in older adults following long-term muscle power or muscle strength spe-cific training. J Gerontol A Biol Sci Med Sci (2008); 63: 751–758. Hortobagyi T, Houmard JA, Stevenson JR, Fraser DD, Johns RA, Israel RG. The effects of detraining on power athletes. Med Sci Sports Exerc (1993); 25: 929–935
Retraining-induced muscle adaptations
  • R Ogasawara
Retraining-induced muscle adaptations, R. Ogasawara et al.
  • R Retraining-Induced Muscle Adaptations
  • Ogasawara
Retraining-induced muscle adaptations, R. Ogasawara et al. Ó 2011 The Authors Clinical Physiology and Functional Imaging Ó 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine 31, 5, 399–404
Designing Resistance Training Programs
  • Sj Fleck
  • Wj Kraemer
Fleck SJ, Kraemer WJ. Designing Resistance Training Programs, 3rd edn (2004). Human Kinetics, Champaign, IL.
The Authors Clinical Physiology and Functional Imaging Ó
  • R Ogasawara
Retraining-induced muscle adaptations, R. Ogasawara et al. Ó 2011 The Authors Clinical Physiology and Functional Imaging Ó 2011 Scandinavian Society of Clinical Physiology and Nuclear Medicine 31, 5, 399-404