| While cryotherapy has direct physiological effects on contractile
tissues, the extent to which joint cooling affects the neuromuscular
system is not well understood. The purpose of the study was to detect
changes in ankle dynamic restraint (peroneal short latency response
and muscle activity amplitude) during inversion perturbation following
ankle joint cryotherapy. A 2x3 factorial design was used to compare
reaction time and EMG amplitude data of treatment conditions (cryotherapy
and control) across time (pre-treatment, post-treatment, and 30 min
post-treatment). Thirteen healthy volunteers (age 23 ± 4 yrs,
ht 1.76 ± 0.09 m, mass 78.8 ± 16.6 kg), with no history
of lower extremity joint injury participated in this study. Surface
EMG was collected from the peroneus longus (PL) of the dominant leg
during an ankle inversion perturbation triggered while walking. Subjects
walked the length of a 6.1 m runway 30 times. A trap door mechanism,
inducing inversion perturbation, was released at heel contact during
six randomly selected trials for each leg. Following baseline measurements,
a 1.5 L bag of crushed ice was applied to the lateral ankle of subjects
in the treatment group with an elastic wrap. A bag similar in weight
and consistency was applied to the lateral ankle of subjects in the
control group. A repeated measures ANOVA was used to compare treatment
conditions across time (p < 0.05). Maximum inversion range of motion
was 28.4 ± 1.8° for all subjects. No overall condition
by time difference was detected (p > 0.05) for PL reaction time.
Average RMS EMG, normalized to an isometric reference position, increased
in the cryotherapy group at the 30 min post-treatment interval relative
to the control group (p < 0.05). Joint cooling does not result
in deficiencies in reaction time or immediate muscle activation following
inversion perturbation compared to a control.
KEY
WORDS: Dynamic stability, reaction time, cryotherapy.
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