Chronic Effect of Static Stretching on Strength Performance and Basal Serum IGF-1 Levels

Abstract

Improving the process of how physical performance is enhanced is one of the main topics evaluated by physiologists. This process often involves athletes and nonathletic populations. The purpose of this study was to assess the chronic response to 10 weeks of static stretching exercises carried out before and during a strength training program for 8 exercises on an 8 repetition maximum (8RM) test performance, and basal serum insulinlike growth factor (IGF-1) levels. Thirty recreationally trained volunteers were randomly assigned to 1 of 3 training groups: (a) SBST (performed a warm-up with a static stretching protocol before each strength training session); (b) SDST (before each training set, a static stretching exercise was performed); and (c) OST (entire session was performed without any type of stretching exercise). Strength and IGF-1 levels were collected at the beginning (pretest) and end (posttest) of the entire experimental procedure. All the exercises showed a significant increase in muscle strength for the OST group. However, the results revealed a significant increase in the muscle strength for only a few exercises in the SBST (LP, LE) and SDST (LP) experimental conditions. Significant statistical differences were found between SBST and SDST for all the exercises in the OST experimental condition. Furthermore, the IGF-1 expression showed no significant differences in the intragroup analysis. However, the OST group showed higher values (p < 0.05) in the posttest when compared with those of the other groups (increased significantly only in the OST experimental condition). It has been concluded that, although all the groups showed an increase in muscular strength, the strength training performed without any type of stretching exercise, regardless of whether the stretching is performed before or during the lifting session, can more effectively increase muscle strength and basal serum IGF-1 levels. It was concluded that strength training, with or without the use of stretching exercises, increased muscular strength in the studied groups, and can induce an increase in IGF-1 levels.

Does Stretching Training Influence Muscular Strength? A Systematic Review With Meta-Analysis and Meta-Regression

“…All studies applied stretching on the lower body involving plantar flexors, knee eor hip extensors and flexors, except two, shoulder horizontal flexors and extensors (82), and shoulder adductors (91), which performed stretching on the lumbar spine extensors. Six studies also applied stretching in the upper body, involving the elbow extensors and shoulder adductors (8,18,29,50,69,79). The most frequent form of stretching intervention was static stretching, although PNF (13,41,56,76), dynamic (3,19,50), and ballistic (42,49) modalities were also performed.…”

“…A more recent study compared traditional RT vs. interset rest stretching RT protocols and did observe a small advantage in muscle thickness for the stretching group but no significant differences in strength gains between the groups (18). Other groups have also tried to explore the effects of stretching combined with RT on measures of strength and observed conflicting results (8,64,81). However, dissimilarities regarding study designs and exercise protocols (e.g., stretch typology, duration, and timing) may explain the dissimilar outcomes.…”

(Neuro) Peptides, Physical Activity, and Cognition

“…Even short 10 min high- or low-intensity exercise bouts elicit increases in serum IGF-1 concentrations [ 96 ]. Strength training induced acute increases [ 30 , 97 , 98 , 99 , 100 ] and raised resting serum IGF-1 levels [ 101 ]. However, other groups studying strength training reported no change in peripheral IGF-1 levels in 18–30 years old [ 33 ], in 18–25 years old [ 102 ], and in 30 and 62 years old [ 90 ] healthy humans.…”

Static stretching - functions and effects: Review

“…Tuto tezi podporuje i práce Mohamada, Nosaka a Cronina (2011) kdy uvádějí, že statický strečink může vyvolávat nervosvalovou, metabolickou a hormonální odezvu s možným zvýšením hypertrofického efektu. Vliv statického strečinku na přírůstek síly z dlouhodobého hlediska zkoumali ve své studii také Borges et al (2013). Tři nezávislé skupiny prováděly po dobu deseti týdnů stejný silový trénink s tím rozdílem, že první skupina zařadila statický strečink do rozcvičení, druhá skupina jej aplikovala před každou posilovací položkou a třetí skupina absolvovala celý program bez strečinku.…”