This study investigated the effect of cryotherapy with carbon dioxide hydrate (CDH) on fatigue recovery of neuromuscular function and muscle blood circulation. Fourteen young males randomly received three types of 20-min recovery interventions (cryotherapy with CDH [CDH-condition] or normal ice [ICE-condition], or quiet sitting at room temperature [CON-condition]) 5 min following a fatiguing task (50 maximal effort isotonic contractions) on three separate days. The isotonic peak power of the knee extensors at 35 min after the fatiguing task in the CDH-condition (95% of baseline) was greater than that in the other conditions (82-89% of baseline; p ≤ 0.031). In addition, at 25 and 35 min after the fatiguing task, the changes in haemoglobin concentration of the knee extensors from before the fatiguing task in the CON-condition (2.5 and 3.0 μmol/L) were different from those in the ICE-condition (-1.4 and -1.3 μmol/L; p ≤ 0.004) but comparable to those in the CDH-condition (1.1 and 0.7 μmol/L; p ≥ 0.060), respectively. These findings suggest that cryotherapy with CDH did not lower the blood volume following the intervention, unlike that with normal ice, and promoted greater immediate recovery of muscle power from neuromuscular fatigue compared with cryotherapy with ice or passive rest.
Keywords: Blood flow; Icing; Isotonic contraction; Near-infrared spectroscopy; Power.