Topical Analgesic Improved or Maintained Ballistic Hip Flexion Range of Motion with Treated and Untreated Legs

Increased stretch tolerance can contribute to improved range of motion (ROM). Since menthol-based topical analgesics (TopAnalg) suppress pain, they may increase stretch thresholds improving ROM. Other modalities such as transcutaneous electrical nerve stimulation and rolling have demonstrated decreased pain sensitivity in the contralateral limb. The purpose of this study was to investigate the effects of a TopAnalg on active and passive ROM of the treated and contralateral (untreated) leg. With a double blind, repeated measures design, 14 university students had a TopAnalg or a placebo gel applied to their hamstrings, rested for 20-min and then either performed static or dynamic stretching. Prior to gel application and after stretching, participants were tested for passive static, active and ballistic hip flexion ROM. Near significant greater ballistic hip flexion ROM for both legs (treated: p = 0.08; 3.6%; contralateral: p = 0.1; 1.6%) were observed with the TopAnalg. With dynamic stretching, ballistic hip flexion ROM of both limbs at post-test (p=0.01-0.007; 3.3-4.2%) and post-10 minutes (p = 0.06-0.01; 2.7-4.1%) decreased with the placebo, whereas there were no significant reductions with the TopAnalg. There was a near significant higher active hip flexion ROM (stretched leg: p = 0.05; 4.6%), and significantly higher ballistic hip flexion ROM (p = 0.04-0.05; 3.4-3.5%) with static versus dynamic stretching for both legs. In conclusion, TopAnalg can increase hip flexion ROM of the treated and contralateral limbs. Secondly, static stretching contributed to greater ballistic ROM in both the stretched and non-stretched contralateral limbs. Hence, TopAnalg may be used to enhance flexibility training with rehabilitation or highly trained athletes.