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Skeletal muscle adaptation during early phase of heavy-resistance training in men and women
Abstract
An 8-wk progressive resistance training program for the lower extremity was performed twice a week to investigate the time course for skeletal muscle adaptations in men and women. Maximal dynamic strength was tested biweekly. Muscle biopsies were extracted at the beginning and every 2 wk of the study from resistance-trained and from nontrained (control) subjects. The muscle samples were analyzed for fiber type composition, cross-sectional area, and myosin heavy chain content. In addition, fasting blood samples were measured for resting serum levels of testosterone, cortisol, and growth hormone. With the exception of the leg press for women (after 2 wk of training) and leg extension for men (after 6 wk of training), absolute and relative maximal dynamic strength was significantly increased after 4 wk of training for all three exercises (squat, leg press, and leg extension) in both sexes. Resistance training also caused a significant decrease in the percentage of type IIb fibers after 2 wk in women and 4 wk in men, an increase in the resting levels of serum testosterone after 4 wk in men, and a decrease in cortisol after 6 wk in men. No significant changes occurred over time for any of the other measured parameters for either sex. These data suggest that skeletal muscle adaptations that may contribute to strength gains of the lower extremity are similar for men and women during the early phase of resistance training and, with the exception of changes in the fast fiber type composition, that they occur gradually.
... While serum testosterone levels following heavy RE are acutely elevated in men (Fleck and Kraemer, 2014) they do not change in women after RE (Kraemer et al., 1991;Kraemer et al., 1993;Staron et al., 1994;Hakkinen and Pakarinen, 1995). For GH, the response to RE seems to be similar between gender, as RE induced a post-exercise increase of GH in women and men (Kraemer et al., 1991;Hakkinen and Pakarinen, 1995). ...
... For GH, the response to RE seems to be similar between gender, as RE induced a post-exercise increase of GH in women and men (Kraemer et al., 1991;Hakkinen and Pakarinen, 1995). While research on the acute response of IGF-1 to RE is equivocal (Kraemer et al., 1991;Kraemer et al., 1993;Consitt et al., 2001;Kraemer and Ratamess, 2005), the combination of GH and IGF-1 seems to play a testosterone-compensatory effect in women as women show a markedly increase in fiber CSA as a result of regimented RE (Staron et al., 1994) despite low levels of testosterone. ...
Muscle mass and force are key for movement, life quality, and health. It is well established that resistance exercise is a potent anabolic stimulus increasing muscle mass and force. The response of a physiological system to resistance exercise is composed of non-modifiable (i.e., age, gender, genetics) and modifiable factors (i.e., exercise, nutrition, training status, etc.). Both factors are integrated by systemic responses (i.e., molecular signaling, genetic responses, protein metabolism, etc.), consequently resulting in functional and physiological adaptations. Herein, we discuss the influence of non-modifiable factors on resistance exercise: age, gender, and genetics. A solid understanding of the role of non-modifiable factors might help to adjust training regimes towards optimal muscle mass maintenance and health.
... However, Nimphius et al. [32] have suggested that when the confounding factor of strength is removed (i.e., normalised for lean body mass), there are no significant differences in relative lower-body maximal strength between the sexes. Furthermore, men and women demonstrated similar neural adaptations (i.e., increased motor unit recruitment and synchronisation, and neural activation) [32,33] and improvements in maximal strength following a maximal-strength training intervention. Nevertheless, given the biological differences (i.e., hormonal profile, menstrual cycle), it may be erroneous therefore to apply research conducted on male athletes to female athletes. ...
Background
There has been a rise in the participation, professionalism, and profile of female sports in recent years. Sprinting ability is an important quality for successful athletic performance in many female team sports. However, much of the research to date on improving sprint performance in team sports is derived from studies with male participants. Given the biological differences between the sexes, this may be problematic for practitioners when programming to enhance sprint performance in female team-sport athletes. Therefore, the aims of this systematic review were to investigate (1) the overall effect of lower body strength training on sprint performance, and (2) the effect of specific strength training modalities (i.e., reactive-; maximal-; combined-; special-strength) on sprint performance in female team-sport athletes.
Methods
An electronic database search was performed using PubMed, MEDLINE, SPORTDiscus, CINAHL, The Cochrane Library, and SCOPUS to identify relevant articles. A random-effects meta-analysis was performed to establish standardised mean difference with 95% confidence intervals and the magnitude and direction of the effect.
Results
Fifteen studies were included in the final analysis. The 15 studies represent a total sample size of 362 participants (intervention n = 190; control n = 172) comprising 17 intervention groups and 15 control groups. The overall effects revealed small improvements in sprint performance in favour of the experimental group over 0–10 m and moderate improvements over sprint distances of 0–20 m and 0–40 m. The magnitude of improvement in sprint performance was influenced by the strength modality (i.e., reactive-, maximal-, combined-, and special-strength) utilised in the intervention. Reactive- and combined-strength training methods had a greater effect than maximal- or special-strength modalities on sprint performance.
Conclusion
This systematic review and meta-analysis demonstrated that, when compared with a control group (i.e., technical and tactical training), the different strength training modalities exhibited small to moderate improvements in sprint performance in female team-sport athletes. The results of a moderator analysis demonstrated that youth athletes (< 18 years) yielded a greater improvement in sprint performance compared with adults (≥ 18 years). This analysis also supports the use of a longer programme duration (> 8 weeks) with a higher total number of training sessions (> 12 sessions) to improve overall sprint performance. These results will serve to guide practitioners when programming to enhance sprint performance in female team-sport athletes.
... The core training might have caused neural adaptations. These adaptations involve more efficient neural recruitment patterns, faster nervous system activation, and improved synchronization of motor units and lowering of neural inhibitory reflexes [28]. ...
... Thus, lumbopelvic instability may increase stress in glenohumeral joint and lead to the occurrence of injuries in overhead athletes over time (Endo & Sakamoto, 2014a;Silfies, Ebaugh, Pontillo, & Butowicz, 2015;Wilk, Arrigo, Hooks, & Andrews, 2016). Core's neuromuscular control and strength may also influence athletic performance by allowing generation of adequate strength, efficient movements patterns and optimized muscle recruitment (Hibbs, Thompson, French, Wrigley, & Spears, 2008;Kibler et al., 2006;Staron et al., 1994). In addition, lower limb factors have been associated with efficiency in overhead activity (Chu et al., 2016). ...
Abstract
Objective
To identify the association of trunk and lower limb factors with shoulder complaints and sport performance in overhead athletes.
Methods
Search performed at PubMed/Medline, Embase, CINAHL, LILACS, Cochrane, Web of Science and SPORTDiscus for observational studies. Methodological quality and strength of the evidence was assessed with the Newcastle-Ottawa Scale and GRADE. Meta-analysis and effects sizes analysis were calculated when possible.
Results
Sixty-five studies were included. Low to very-low evidence suggests no association of trunk/lower limb strength, endurance, power, jump or balance with shoulder complaints and/or throwing performance. Athletes with shoulder complaints performed worse in trunk stability and endurance tests (mean difference: −6.83 (95%CI: −8.78, −4.88)). Athletes with high throwing performance presented better results in CMJ, horizontal jump, power measures and knee extension strength. For swimmers, there was no association of trunk/lower limb endurance with shoulder complaints (moderate evidence) and no association of balance and swimming performance (low evidence). Better trunk/lower limb strength, power and vertical jumps measures were associated with better swimming performance.
Conclusions
In methodologically similar studies, some trunk/lower limb outcomes are associated with shoulder complaint or sport/swimming performance. Results should be considered with caution and future studies should use better methodologies.
Humans are unique among terrestrial mammals in our manner of walking and running, reflecting 7 to 8 Ma of musculoskeletal evolution since diverging with the genus Pan. One component of this is a shift in our skeletal muscle biology towards a predominance of myosin heavy chain (MyHC) I isoforms (i.e. slow fibers) across our pelvis and lower limbs, which distinguishes us from chimpanzees. Here, new MyHC data from 35 pelvis and hind limb muscles of a Western gorilla (Gorilla gorilla) are presented. These data are combined with a similar chimpanzee dataset to assess the MyHC I content of humans in comparison to African apes (chimpanzees and gorillas) and other terrestrial mammals. The responsiveness of human skeletal muscle to behavioral interventions is also compared to the human-African ape differential. Humans are distinct from African apes and among a small group of terrestrial mammals whose pelvis and hind/lower limb muscle is slow fiber dominant, on average. Behavioral interventions, including immobilization, bed rest, spaceflight and exercise, can induce modest decreases and increases in human MyHC I content (i.e. -9.3% to 2.3%, n = 2033 subjects), but these shifts are much smaller than the mean human-African ape differential (i.e. 31%). Taken together, these results indicate muscle fiber content is likely an evolvable trait under selection in the hominin lineage. As such, we highlight potential targets of selection in the genome (e.g. regions that regulate MyHC content) that may play an important role in hominin skeletal muscle evolution.
We sought to determine if the myofibrillar protein synthetic (MyoPS) response to a naïve resistance exercise (RE) bout, or chronic changes in satellite cell number and muscle ribosome content, were associated with hypertrophic outcomes in females or differed in those who classified as higher (HR) or lower (LR) responders to resistance training (RT). Thirty-four untrained college-aged females (23.4±3.4 kg/m2) completed a 10-week RT protocol (twice weekly). Body composition and leg imaging assessments, a right leg vastus lateralis biopsy, and strength testing occurred before and following the intervention. A composite score, which included changes in whole-body lean tissue mass (LSTM), vastus lateralis (VL) muscle cross-sectional area (mCSA), mid-thigh mCSA, and deadlift strength, was used to delineate upper and lower HR (n=8) and LR (n=8) quartiles. In all participants, training significantly (p<0.05) increased LSTM, VL mCSA, mid-thigh mCSA, deadlift strength, mean muscle fiber cross-sectional area, satellite cell abundance, and myonuclear number. Increases in LSTM (p<0.001), VL mCSA (p<0.001), mid-thigh mCSA (p<0.001), and deadlift strength (p=0.001) were greater in HR versus LR. The first-bout 24-hour MyoPS response was similar between HR and LR (p=0.367). While a no significant responder*time interaction existed for muscle total RNA concentrations (i.e., ribosome content) (p=0.888), satellite cell abundance increased in HR (p=0.026) but not LR (p=0.628). Pre-training LSTM (p=0.010) VL mCSA (p=0.028), and mid-thigh mCSA (p<0.001) were also greater in HR versus LR. Female participants with an enhanced satellite cell response to RT, and more muscle mass prior to RT, exhibited favorable resistance training adaptations.
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