Abstract details

Abstract-ID: 1184
Title of the paper: TIME COURSE OF MUSCLE TENDON FUNCTION AND STRUCTURE FOLLOWING A FIVE MINUTE STATIC STRETCHING EXERCISE
Authors: Konrad, A., Tilp, M.
Institution: Karl- Franzens- University Graz
Department: Institute of Sport Science
Country: Austria
Abstract text INTRODUCTION:
Previous studies have shown that a single static stretching exercise decreases muscle stiffness immediately after the stretch, which recovered 30 minutes after the stretching (Kay and Blazevich, 2012). However, the precise time course of the response of muscle and tendon properties (e.g. muscle stiffness) and function responses (e.g. range of motion (RoM)) within the first 10 min minutes after stretching are not yet known. Therefore, the purpose of this study was to investigate the time course of the changes of the various muscle and tendon mechanical properties and the function responses of the gastrocnemius medialis (GM) and the Achilles tendon (AT) following 5 min of static stretching.
METHODS:
Fourteen healthy volunteers (seven healthy females (mean SD; 24.9 3.1 years, 166.0 6.1 cm, 60.0 8.4 kg) and seven healthy males (mean SD; 27.5 8.3 years, 180.1 6.2 cm, 75.9 6.5 kg)) were tested on four separate days in a random order with three different rest times (0 min, 5 min, 10 min) after 560s of stretching or following a control period without stretching. During each test, the dorsiflexion RoM, passive resistive torque (PRT), and maximum voluntary contraction (MVC) were measured with a dynamometer. Ultrasonography of the GM muscle-tendon junction displacement and motion capture allowed us to determine length changes in the AT and GM, respectively, and hence to calculate their stiffness. Two-way repeated-measures ANOVA tests or Friedman tests were performed to test for differences between the conditions.
RESULTS:
Following the stretching, we observed a significant increase in RoM and a decrease in MVC at 0 min, 5 min, and 10 min post-stretching. This could be attributed to an increase in muscle elongation which also lasted at least 10 min. Furthermore, a significant decrease in PRT and muscle stiffness was observed up to 5 min after the stretching. A decrease in muscle-tendon stiffness was observed immediately, but not 5 or 10 min after the stretching. No changes in tendon stiffness or in any variable in the control group were detected.
CONCLUSION:
We conclude that the effects of a 560s static stretching exercise changes the muscle-tendon functions (RoM, MVC), which are related to mechano-morphological changes of the muscle but not the tendon structure, respectively. Although the functional changes last for at least 10 min, changes in muscle stiffness recover within 5 min of the stretching. Hence, we speculate that other factors, such as increased stretch tolerance (Magnusson et al. 1996), lead to longer-lasting changes of muscle-tendon function.

REFERENCES:
Kay AD, Blazevich AJ. J Appl Physiol 2009;106:12491256.
Magnusson SP, Simonsen EB, Aagaard P, Dyhre-Poulsen P, McHugh MP, Kjaer M. Arch Phys Med Rehabil 1996;77:373378.
CONTACT:
andreas.konrad@uni-graz.at

Topic: Biomechanics
Keyword I: stretching
Keyword II: stiffness
Keyword III: stretch tolerance