Partial-body cryostimulation does not impact peripheral microvascular responsiveness but reduces muscular metabolic...

This study aimed to investigate the effect of partial-body cryostimulation (PBC) on microvascular responsiveness and muscular metabolic O₂ consumption rate (mV˙O₂). Twenty healthy young adults (ten males and ten females) underwent a post-occlusive reactive hyperemia (PORH) test at the flexor digitorum superficialis area before and after a 3-min PBC session and a 3-min control session. Using near-infrared spectroscopy, occlusion and reperfusion slopes were calculated: oxyhemoglobin ([HbO₂]) decrease rate ([HbO₂] slope 1), deoxyhaemoglobin ([HHb]) increase rate ([HHb] slope 1), [HbO₂] increase rate ([HbO₂] slope 2), and [HHb] increase rate ([HHb] slope 2. Using HbO₂ kinetics during the occlusion, mV˙O₂ was also calculated to characterize myocytes' metabolic O₂ consumption. HbO₂ slope 1 value was lower after PBC than before PBC (-0.15 ± 0.08 vs -0.24 ± 0.11 s^-1; respectively; P < 0.05) in male participants only. A lower [HHb] slope 1 was also observed after PBC compared to before PBC (0.18 ± 0.10 vs 0.24 ± 0.16 s^-1; P < 0.05) with no interaction for sex categories. mV˙O₂ was significantly lower after PBC than before (pre values 14.75 ± 3.94 vs 18.47 ± 5.73 μMO₂Hb.s^-1; respectively; P < 0.01) with no interaction between sex categories. No changes in the calculated slope 2 were observed. These findings suggest that a single session of PBC reduces the muscular metabolic O₂ needs at rest; however, it does not alter the vascular ability to provide O₂ to the myocytes.