Carbon dioxide hydrate as a recovery tool after fatigue of the plantar flexors

This study investigated the effects of cooling the triceps surae with carbon dioxide hydrate (CDH), which is a gas hydrate, a crystalline structure belonging to the clathrates, on the recovery from muscle fatigue. Thirty-six healthy young men were equally and randomly assigned to an ICE group, a CDH group, or a non-cooling (NON) group. All participants performed 80 maximal voluntary isometric contractions (MVCs) of the plantar flexors as a fatiguing task. MVC torque and voluntary activation were determined before, immediately after, and 20 min after the fatiguing task. Evoked torque was similarly assessed except for immediately after the task. In the ICE and CDH groups, the triceps surae was cooled for 5 min using ice and CDH, starting 5 min after the fatiguing task, respectively. The MVC torque and voluntary activation were higher in order of before >20 min after >immediately after the fatiguing task regardless of group, and those time-course changes did not differ between the groups. A decrease in the evoked torque from before to 20 min after the fatiguing task was observed in the ICE and NON groups but not in the CDH group. These results suggest that cooling muscle with CDH can facilitate recovery from peripheral muscle fatigue. This may be due to an increase in blood flow caused by carbon dioxide contained within the CDH, and indicates the potential of CDH as a recovery tool after fatiguing exercise.