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THE JOURNAL OF SPORTS MEDICINE AND PHYSICAL FITNESS
A Journal on Applied Physiology, Biomechanics, Preventive Medicine,
Sports Medicine and Traumatology, Sports Psychology
Indexed/Abstracted in: Chemical Abstracts, CINAHL, Current Contents/Clinical Medicine, EMBASE, PubMed/MEDLINE, Science Citation Index Expanded (SciSearch), Scopus
Impact Factor 1,111
The Journal of Sports Medicine and Physical Fitness 2017 Apr 13
Copyright © 2017 EDIZIONI MINERVA MEDICA
Effects of stretching and fatigue on peak torque, muscle imbalance and stability
Pablo B. COSTA 1 ✉, Cassio V. RUAS 2, Cory M. SMITH 3
1 Exercise Physiology Laboratory, Department of Kinesiology, California State University, Fullerton, CA; 2 School of Physical Education, Federal University of Rio Grande do Sul, Brazil; 3 Department of Nutrition and Health Sciences, University of Nebraska-Lincoln, Lincoln, NE
BACKGROUND: The present study examined the acute effects of hamstrings stretching and fatigue on knee extension and flexion peak torque (PT), hamstrings to quadriceps (H:Q) ratio, and postural stability.
METHODS: Seventeen women (mean ± SD age = 21.8 ± 2.1 yrs; body mass = 63.0 ± 10.5 kg; height = 164.7 ± 6.2 cm) and eighteen men (25.8 ± 4.6 yrs; 83.6 ± 13.2 kg; 175.3 ± 6.0 cm) took part in three laboratory visits. The first visit was a familiarization session, and the subsequent two visits were randomly assigned as a control or stretching condition. For the testing visits, subjects performed a postural stability assessment, stretched (or sat quietly during the control condition), performed a 50-repetition unilateral isokinetic fatigue protocol, and repeated the postural stability assessment.
RESULTS: There were no significant differences between control and stretching conditions for initial quadriceps and hamstrings PT, initial H:Q ratio, quadriceps and hamstrings PT fatigue indexes, H:Q ratio fatigue index, rating of perceived exertion (RPE), or postural stability (p >0.05). When analyzing 5 intervals of 10 repetitions, significant declines in quadriceps PT were found in all intervals for both conditions (p < 0.05). However, a decline in hamstrings PT was only found until the fourth interval (i.e., repetitions 31 to 40) for the stretching condition (p < 0.05).
CONCLUSIONS: Stretching the hamstrings immediately prior to long-duration activities may eventually cause adverse effects in force-generating capacity of this muscle group to occur earlier when fatiguing tasks are involved. Nevertheless, no changes were found for the H:Q ratios after stretching when compared to no-stretching.
KEY WORDS: Stretching-induced - Balance - Strength - Asymmetry