Specificity of arm training on aerobic power during swimming and running.

The specificity of aerobic training for upper-body exercise requiring differing amounts of muscle mass was evaluated in 25 college-aged male recreational swimmers who were randomly assigned to either a non-training control group (N = 9), a 10-wk swim(S)-training group (N = 9), or a group that trained with a standard swim-bench pulley system (SB; N = 7). For all subjects prior to training, tethered-swimming peak VO2 averaged 19% below treadmill values (P less than 0.01), while SB-ergometry peak VO2 was 50% and 39% below running and swimming values, respectively (P less than 0.01). Significant (P less than 0.01) increases of peak VO2 in tethered swimming (11%) and SB (21%) were observed for the SB-trained group, while the S-trained group improved (P less than 0.01) 18% and 19% on the tethered swimming and SB tests, respectively. No changes were observed during treadmill running, and the control subjects remained unchanged on all measures. Comparisons between training groups indicated that although both groups improved to a similar extent when measured on the swim bench, the 0.53 l X min-1 improvement in tethered-swimming peak VO2 for the S-trained group was greater (P less than 0.05) than the 0.32 l X min-1 increase noted for the SB-trained group. The comparisons between SB and S exercise vs treadmill exercise support the specificity of aerobic improvement with training and suggest that local adaptations contribute significantly to improvements in peak VO2. Furthermore, the present data indicate that SB exercise activates a considerable portion of the musculature involved in swimming, and that aerobic improvements with SB training are directly transferred to swimming.

Thermal adjustment to cold-water exposure in resting men and women.

Thermoregulatory responses were studied in 10 men and 8 women at rest in air and during 1-h immersion in water at 20, 24, and 28 degrees C. For men of high body fat (27.6%), rectal temperature (Tre) and oxygen consumption (VO2) were maintained at air values at all water temperatures (Tw). For men of average (16.8%) and low (9.2%) fat the change in Tre (delta Tre) was inversely related to body fat at all Tw with VO2 increasing to 1.07 l X min-1 for a -1.6 degrees C delta Tre for lean men. For women of average (25.2%) and low (18.5%) fat Tre decreased steadily during immersion at all Tw. The greatest changes occurred at 20 degrees C with little differences in delta Tre and VO2 noted between these groups of women. In comparison with males of similar percent fat, Tre dropped to a greater extent (P less than 0.05) in females at 20 and 24 degrees C. Stated somewhat differently, lean women with twice the percentage of fat have similar delta Tre as lean men at all Tw. For delta Tre greater than -1.0 degree C men showed significantly greater (P less than 0.05) thermogenesis compared with women. The differences in thermoregulation between men and women during cold stress at rest may be due partly to the sensitivity of the thermogenic response as well as the significant differences in lean body weight and surface area-to-mass ratio between the sexes.

Thermal adjustment to cold-water exposure in exercising men and women.

Thermoregulatory responses were studied in 10 men and 8 women during 36-W exercise for 1 h in air and water at 20, 24, and 28 degrees C. Men were classified as high (27.6%; n = 2), average (16.8%; n = 4), and low (9.2%; n = 4) percent body fat, whereas women were classified as average (25.2%; n = 4) and low (18.5%; n = 4) fat. For both men and women, exercise of about 1.7 l O2 X min-1 was beneficial in either preventing or retarding the fall in rectal temperature (Tre) observed in a previous study for the same subjects at rest. The greatest thermal strain was noted for the leanest subjects. However, in no instance did exercise facilitate a drop in Tre compared with resting conditions. Despite a larger surface area-to-mass ratio (P less than 0.05) and less effective thermoregulation for women at rest compared with men, essentially similar thermoregulatory responses were observed for both sexes during exercise at each water temperature. For both the men and women, the thermoregulatory benefits of exercise were due largely to the added heat production from physical activity. For the female, an additional benefit of exercise may in part be derived from a more favorable distribution of subcutaneous fat over the active musculature.