THERMAL AND METABOLIC RESPONSES TO COLD-WATER IMMERSION AT KNEE, HIP,AND SHOULDER LEVELS

To examine the effect of cold-water immersion at different depths on t hermal and metabolic responses, eight men (25 yr old, 16% body fat) at tempted 12 tests: immersed to the knee (K), hip (H), and shoulder (Sh) in 15 and 25 degrees C water during both rest (R) or leg cycling [35% peak oxygen uptake; (E)] for up to 135 min. At 15 degrees C, rectal ( T-re) and esophageal temperatures (T-es) between R and E were not diff erent in Sh and H groups (P > 0.05), whereas both in K group were high er during E than R (P < 0.05). At 25 degrees C, T-re was higher (P < 0 .05) during E than R at all depths, whereas T-es during E was higher t han during R in H and K groups. T-re remained at control levels in K-E at 15 degrees C, K-E at 25 degrees C, and in H-E groups at 25 degrees C, whereas T-es remained unchanged in K-E at 15 degrees C, in K-R at 15 degrees C, and in all 25 degrees C conditions (P > 0.05). During R and E, the magnitude of T-re change was greater (P > 0.05) than the ma gnitude of T-es change in Sh and H groups, whereas it was not differen t in the K group (P > 0.05). Total heat flow was progressive with wate r depth. During R at 15 and 25 degrees C, heat production was not incr eased in K and H groups from control level (P > 0.05) but it did incre ase in Sh group (P < 0.05). The increase in heat production during E c ompared with R was smaller (P < 0.05) in Sh (121 +/- 7 W/m(2) at 15 de grees C and 97 +/- 6 W/m(2) at 25 degrees C) than in H (156 +/- 6 and 126 5 W/m(2), respectively) and K groups (155 +/- 4 and 165 +/- 6 W/m( 2), respectively). These data suggest that T-re and T-es respond diffe rently during partial cold-water immersion In addition, water levels a bove knee in 15 degrees C and above hip in 25 degrees C cause depressi on of internal temperatures mainly due to insufficient heat production offsetting heat loss even during light exercise.