Stretching Combined With Tens Or Self-massage Has Differential Effects On Ankle Flexibility

Abstract

Many studies evaluating the effect of stretching conclude that gains in flexibility are primarily due to improved stretch tolerance (discomfort). Under this rationale, use of pain reduction therapies while stretching should provide greater improvements in flexibility than stretching alone. Transcutaneous electrical nerve stimulation (TENS) is a modality commonly used to mitigate pain. Self-massage with a foam roller, which may modulate the mechanical properties of connective tissues, has been shown to improve flexibility. PURPOSE: To compare the influence of TENS and self-massage on ankle joint flexibility and force capacity of the plantar flexor muscles after a stretching intervention. METHODS: 20 healthy young adults (10M, 10F, mean (SD) age 25 (3) y) underwent 3 sessions of ankle plantar flexor stretching: stretching alone (SS), stretching with concurrent application of TENS (TS), and stretching after self-massage using yoga therapy balls (BS). Each visit was separated by one week. All subjects performed SS at the first visit; the remaining 2 visits were counterbalanced. At every visit, subjects performed isometric maximum voluntary contractions (MVCs) for the plantar flexors before and after the intervention. Stretching involved three 30-s standing calf stretches, separated by 30-s rest. TENS was applied at a comfortable current without muscle contraction for 1-min prior to, and for the duration of stretching. Massage with yoga balls was performed for 60-s immediately prior to each of the 3 stretches. Ankle dorsiflexion range of motion (ROM) was assessed before, immediately after, and at 1, 5, 10, and 15 min after the intervention. RESULTS: All 3 interventions significantly increased ankle dorsiflexion ROM (all p=0.00). The mean (SD) change in ROM was 13 (9)%, 9 (7)%, and 25 (17)% for SS, TS, and BS, respectively. The mean (SD) change in ankle torque was -1(13)%, -3 (10)%, and 16 (11)% for SS, TS, and BS, respectively. In contrast to TENS (TS), the use of yoga therapy balls significantly increased ROM and MVC torque (both p=0.00, effect size 0.40, 0.58 for ROM, torque). CONCLUSION: The addition of TENS to a stretch intervention did not improve ankle joint range of motion or alter MVC force. In contrast, self-massage with yoga therapy balls prior to stretching significantly improved range of motion and MVC force.