Observational Study
Copyright ©The Author(s) 2015. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Orthop. Oct 18, 2015; 6(9): 719-726
Published online Oct 18, 2015. doi: 10.5312/wjo.v6.i9.719
Acute effects of static stretching on peak and end-range hamstring-to-quadriceps functional ratios
Ufuk Sekir, Ramiz Arabaci, Bedrettin Akova
Ufuk Sekir, Bedrettin Akova, Department of Sports Medicine, Medical Faculty of Uludag University, 16059 Gorukle, Bursa, Turkey
Ramiz Arabaci, Department of Physical Education and Sport Education, Faculty of Sport Sciences, Uludag University, 16059 Gorukle, Bursa, Turkey
Author contributions: Sekir U and Arabaci R contributed to concept and design the manuscript, collected the data and/or contributed to processing and literature search; Akova B contributed to supervision; Sekir U and Akova B contributed to resource, analysis and/or interpretation; Sekir U wrote the paper; Arabaci R and Akova B contributed to critical reviews.
Institutional review board statement: The study was reviewed and approved by the Uludag University Faculty of Medicine Institutional Review Board.
Informed consent statement: All study participants provided informed written consent prior to study enrollment.
Conflict-of-interest statement: There are no conflicts of interests between any author or institution.
Data sharing statement: Technical appendix, statistical code, and dataset available from the corresponding author at ufuksek@gmail.com. Consent was not obtained but the presented data are anonymized and risk of identification is low.
Open-Access: This article is an open-access article which was selected by an in-house editor and fully peer-reviewed by external reviewers. It is distributed in accordance with the Creative Commons Attribution Non Commercial (CC BY-NC 4.0) license, which permits others to distribute, remix, adapt, build upon this work non-commercially, and license their derivative works on different terms, provided the original work is properly cited and the use is non-commercial. See: http://creativecommons.org/licenses/by-nc/4.0/
Correspondence to: Ufuk Sekir, MD, Professor, Department of Sports Medicine, Medical Faculty of Uludag University, Uludağ Üniversitesi Tıp Fakültesi Dekanlığı, 16059 Gorukle, Bursa, Turkey. ufuksek@gmail.com
Telephone: +90-224-2953500 Fax: +90-224-2950099
Received: March 2, 2015
Peer-review started: March 3, 2015
First decision: June 9, 2015
Revised: July 22, 2015
Accepted: August 10, 2015
Article in press: August 11, 2015
Published online: October 18, 2015
Abstract

AIM: To evaluate if static stretching influences peak and end-range functional hamstring-to-quadriceps (H/Q) strength ratios in elite women athletes.

METHODS: Eleven healthy female athletes in an elite competitive level participated to the study. All the participants fulfilled the static stretching or non-stretching (control) intervention protocol in a randomized design on different days. Two static unassisted stretching exercises, one in standing and one in sitting position, were used to stretch both the hamstring and quadriceps muscles during these protocols. The total time for the static stretching was 6 ± 1 min. The isokinetic peak torque measurements for the hamstring and quadriceps muscles in eccentric and concentric modes and the calculations for the functional H/Q strength ratios at angular velocities of 60°/s and 180°/s were made before (pre) and after (post) the control or stretching intervention. The strength measurements and functional strength ratio calculations were based during the entire- and end-range of knee extension.

RESULTS: The pre-test scores for quadriceps and hamstring peak torque and end range values were not significantly different between the groups (P > 0.05). Subsequently, although the control group did not exhibit significant changes in quadriceps and hamstring muscle strength (P > 0.05), static stretching decreased eccentric and concentric quadriceps muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). Similarly, static stretching also decreased eccentric and concentric hamstring muscle strength at both the 60°/s and 180°/s test speeds (P < 0.01). On the other hand, when the functional H/Q strength ratios were taken into consideration, the pre-intervention values were not significant different between the groups both during the entire and end range of knee extension (P > 0.05). Furthermore, the functional H/Q strength ratios exhibited no significant alterations during the entire and end ranges of knee extension both in the static stretching or the control intervention (P > 0.05).

CONCLUSION: According to our results, static stretching routine does not influence functional H/Q ratio. Athletes can confidently perform static stretching during their warm-up routines.

Keywords: Elite women athletes, Eccentric, Concentric, Static stretching, Functional hamstring-to-quadriceps ratio, Muscle strength

Core tip: Despite the well-known effects of static stretching on muscle strength its effects about the characteristics of injury risk have not been investigated thoroughly. Functional hamstring-to-quadriceps (H/Q) strength ratio that reflects imbalance in thigh muscle strength is one of the etiologic risk factors for sports injuries. There are few studies in the literature investigating the relationship between static stretching and injury risk characteristics. The results of this study demonstrate that static stretching does not influence the functional H/Q ratio. Hereby, our findings also show that static stretching does not increase the risk for injury.