Application of carbon dioxide to the skin and muscle oxygenation of human lower-limb muscle sites during cold water immersion

Figure 1. Photograph of CO2-rich cold water immresion. Photograph of a subject immersing the right lower leg up to the knee for 15 min in CO2-rich cold water.

Figure 2. The subjects’ mean arterial pressure, heart rate, core temperature, and visual anagoge scale. The subjects’ mean arterial pressure (MAP: A), heart rate (HR: B), core temperature (Tcore: C), and visual anagoge scale (VAS: D) values in the CCWI and CWI protocols. Mean values in 20 sec and standard error are shown throughout the experiment. Blue circles: CWI at 20 °C. Red circles: CCWI at 20 °C.

Figure 3. The subjects’ skin temperature at the immersed leg and non-immersed leg. Mean values of skin temperature at the immersed leg (Tsk-WI; A) and non-immersed leg (Tsk-cont; B). Blue circles: CWI at 20 °C. Red circles: CCWI at 20 °C. Time effect from baseline: *p < 0.05, **p < 0.01 from BL. Simple main effect: †p < 0.05, ††p < 0.01 between CCWI and CWI at the same time point.

Figure 4. Changes of oxygenation, deoxygenation, and total hemoglobin kinetics in the tibialis anterior muscle. Changes of oxygenation (oxy [Hb+Mb]), deoxygenation (Deoxy [Hb+Mb]), and total hemoglobin (total [Hb+Mb]) kinetics from the basal level in the superficial layer (A–C) and muscle layer (D–F) of the tibialis anterior (TA) muscle. Time effect from baseline: *p < 0.05, **p < 0.01 from BL. Simple main effect: †p < 0.05, ††p < 0.01 between CCWI and CWI at the same time point. Time bins and symbols are the same as in Fig. 3.

Figure 5. Changes of oxygenation, deoxygenation, and total hemoglobin (total [Hb+Mb]) kinetics in the gastrocnemius (GAS) muscle. Changes of oxygenation (oxy [Hb+Mb]), deoxygenation (Deoxy [Hb+Mb]), and total hemoglobin (total [Hb+Mb]) kinetics from the basal level in the superficial layer (A–C) and muscle layer (D–F) of the gastrocnemius (GAS) muscle. Time effect from baseline: *p < 0.05, **p < 0.01 from BL. Simple main effect: †p < 0.05, ††p < 0.01 between CCWI and CWI at the same time point. Time bins and symbols are the same as in Fig. 3.

Figure 6. Changes of muscle oxygen saturation (ΔStO2) in TA muscle and GAS muscle between the CCWI and CWI. Changes of muscle oxygen saturation (ΔStO2) in TA muscle (A, C) and GAS muscle (B, D) between the CCWI and CWI. Time effect from baseline: *p < 0.05, **p < 0.01 from BL. Simple main effect: †p < 0.05, ††p < 0.01 between CCWI and CWI at the same time point. Time bins and symbols are the same as in Fig. 3.