AUTHOR=Brownstein Callum G. , Ansdell Paul , Škarabot Jakob , McHugh Malachy P. , Howatson Glyn , Goodall Stuart , Thomas Kevin 

TITLE=The Effect of Phase Change Material on Recovery of Neuromuscular Function Following Competitive Soccer Match-Play

JOURNAL=Frontiers in Physiology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2019.00647

DOI=10.3389/fphys.2019.00647

ISSN=1664-042X

ABSTRACT=<p><bold>Aim:</bold> Cryotherapy is commonly implemented following soccer match-play in an attempt to accelerate the natural time-course of recovery, but the effect of this intervention on neuromuscular function is unknown. The aim of the present study was to examine the effect of donning lower-body garments fitted with cooled phase change material (PCM) on recovery of neuromuscular function following competitive soccer match-play.</p><p><bold>Methods:</bold> Using a randomized, crossover design, 11 male semi-professional soccer players wore PCM cooled to 15°C (PCM<sub>cold</sub>) or left at ambient temperature (PCM<sub>amb</sub>; sham control) for 3 h following soccer match-play. Pre-, and 24, 48, and 72 h post-match, participants completed a battery of neuromuscular, physical, and perceptual tests. Maximal voluntary contraction force (MVC) and twitch responses to electrical (femoral nerve) and magnetic (motor cortex) stimulation (TMS) during isometric knee-extension and at rest were measured to assess central nervous system (CNS) (voluntary activation, VA) and muscle contractile (quadriceps potentiated twitch force, Q<sub>tw,pot</sub>) function. Fatigue and perceptions of muscle soreness were assessed via visual analog scales, and physical function was assessed through measures of jump [countermovement jump (CMJ) height and reactive strength index (RSI)] performance. A belief questionnaire was completed pre- and post-intervention to determine the perceived effectiveness of each garment.</p><p><bold>Results:</bold> Competitive soccer match-play elicited persistent decrements in MVC, VA measured with femoral nerve stimulation, Q<sub>tw,pot</sub>, as well as reactive strength, fatigue and muscle soreness (<italic>P</italic> &lt; 0.05). Both MVC and VA were higher at 48 h post-match after wearing PCM<sub>cold</sub> compared with PCM<sub>amb</sub> (<italic>P</italic> &lt; 0.05). However, there was no effect of PCM on the magnitude or time-course of recovery for any other neuromuscular, physical function, or perceptual indices studied (<italic>P</italic> &gt; 0.05). The belief questionnaire revealed that players perceived that both PCM<sub>cold</sub> and PCM<sub>amb</sub> were moderately effective in improving recovery, with no difference between the two interventions (<italic>P</italic> = 0.56).</p><p><bold>Conclusion:</bold> Although wearing cooled PCM garments improved MVC and VA 48 h following match-play, the lack of effect on measures of physical function or perceptual responses to match-play suggest that PCM offers a limited benefit to the recovery process. The lack of effect could have been due to the relatively small magnitude of change in most of the outcome measures studied.</p>