I. Moustafa1, A. Ahbouch1, L. Walton2
1University of Sharjah, Physiotherapy, Sharjah, United Arab Emirates, 2University of Scranton, Physiotherapy, Scranton, United States
Background: As aging affects the crystallinity of the collagen fibers and reduces the extensibility, the biomechanical protection via different connective tissue layers might be affected .Thus, safe or unsafe limits of nerve elongation are not well established, despite several basic scientific and clinical studies. Of interest, comparison and subsequent conclusions about appropriate hamstring stretching times are mainly based on mechanical factors such as range of motion ,static passive torque , dynamic passive torque ,and stiffness, while ignoring the neural adversative mechanical tension that may be created during stretching exercises. Although it appears that longer-duration stretching enhances ROM increases in elderly people, many questions remain unanswered with regard the adverse neural effect.Consequently, in the present study, we aimed to answer the question: Is it theoretically possible, that increased longitudinal strain and stress on the neural elements from continuous stretching exercises may subtly impair the neural function?
Purpose: To explore the effect of variable stretching durations on neural functions and knee joint range of motion (ROM) in elderly subjects.
Methods: In this trial, 168 participants (mean age=66 years, SD=6) diagnosed with tight hamstring muscles (defined as the inability to extend the knee to less than 20° of knee flexion) were randomly assigned to the control group or one of the 3 intervention groups. The three experimental groups was stretched for 15, 30, and 60 seconds, the control group did not stretch .The primary outcome measures included peak to peak amplitude of somatosensory evoked potential for dermatomes L3, L4, L5, and S1. Secondary outcome measures included knee ROM. All outcome measures were assessed immediately after the treatment session and 24 hours after the treatment session.
Results: A 2-way repeated measures ANOVA revealed significant differences between the four groups. The post hoc analysis indicated that stretching for 60 seconds significantly decreased the dermatomal amplitude for L3, L4, L5 and S1 (P<.001) and significantly increased the Knee ROM(P<.001). While stretching for 30 seconds significantly increased the Knee ROM (P<.001) without any significant effect of DSSEPs (P>.05).
Conclusion(s): Stretching hamstring for 30 seconds was optimal in achieving stretching benefits and minimizing the negative effects on the neural function of the involved nerve roots. Thus, long duration stretching of hamstring at end ranges of motion that place increased stress and strain on the nervous system should be avoided.
Implications: These results should assist in optimizing the stretching time of involved tissues in order to achieve the well-established goals from stretching while avoiding any negative effects on the neural function for the elderly subjects . Although it appears that longer-duration stretching enhances ROM increases in elderly people, stretching for 60s adversely affect the neural function and these negative impacts lasted for at least 24 hours. Since 60s of stretching did not bring any additional benefits compared to 30s of stretching regarding ROM, the use of longer stretches should be questioned.
Funding, acknowledgements: This project is a self funded project.
Keywords: Randomized controlled trial, Stretching, Hamstring muscles
Topic: Older people
Did this work require ethics approval? Yes
Institution: University of Sharjah
Committee: University of Sharjah Research Ethics Committee
Ethics number: REC-19-10-31-02-S
All authors, affiliations and abstracts have been published as submitted.
