Protective clothing (PPC) can have negative effects on worker performance. Currently little is known about the metabolic effects of PPC and previous work has been limited to a few garments and simple walking or stepping. This study investigated the effects of a wide range of PPC on energy consumption during different activities. It is hypothesized that wearing PPC would significantly increase metabolic rate, disproportionally to its weight, during walking, stepping and an obstacle course. Measuring a person's oxygen consumption during work can give an indirect, but accurate estimate of energy expenditure (metabolic rate). Oxygen consumption was measured during the performance of continuous walking and stepping, and an obstacle course in 14 different PPC ensembles. Increases in perceived exertion and in metabolic rate (2.4-20.9%) when wearing a range of PPC garments compared to a control condition were seen, with increases above 10% being significant (P < 0.05). More than half of the increase could not be attributed to ensemble weight.

We examined differences in dynamic heat balance between males and females during intermittent exercise. Six males (M) and six females (F) performed three 30-min bouts of exercise (Ex1, Ex2, Ex3) at a constant rate of metabolic heat production (M - W) of approximately 500 W separated by three 15-min periods of inactive recovery. Rate of total heat loss (M - W) was measured by direct calorimetry, while M - W was determined by indirect calorimetry. Esophageal (T (es)) was measured continuously. Exercise at a constant M - W of approximately 500 W, was paralleled by a similar HL between sexes at the end of Ex1 (M: 462 +/- 30 W, F: 442 +/- 9 W, p = 0.117), Ex2 (M: 468 +/- 28 W, F: 508 +/- 18 W, p = 0.343), and Ex3 (M: 469 +/- 17 W, F: 465 +/- 13 W, p = 0.657). Consequently, changes in body heat content were comparable after Ex1 (M: 218 +/- 21 kJ, F: 287 +/- 35 kJ, p = 0.134), Ex2 (M: 109 +/- 18 kJ, F: 158 +/- 29 kJ, p = 0.179), and Ex3 (M: 92 +/- 19 kJ, F: 156 +/- 35 kJ, p = 0.136). However, females had greater overall increases in T (es) at the end of Ex3 (M: 0.55 +/- 0.25 degrees C, F: 0.97 +/- 0.26 degrees C, p

The proportional decrease in the amount of heat stored in the successive exercise bouts is the result of an enhanced rate of heat dissipation during exercise and not due to a higher rate of heat loss in the recovery period. Despite a greater thermal drive with repeated exercise, the decline in the rate of total heat loss during successive recovery bouts was the same.

This study evaluated the effect of body adiposity on core cooling rates, as measured by decreases in rectal (T (re)), esophageal (T (es)) and aural canal (T (ac)) temperatures, of individuals rendered hyperthermic by dynamic exercise in the heat. Seventeen male participants were divided into two groups; low body fat (LF, 12.9 +/- 1.9%) and high body fat (HF, 22.3 +/- 4.3%). Participants exercised at 65% of their maximal oxygen uptake at an ambient air temperature of 40 degrees C until T (re) increased to 40 degrees C or until volitional fatigue. Following exercise, participants were immersed up to the clavicles in an 8 degrees C circulated water bath until T (re) returned to 37.5 degrees C. No significant differences were found between the LF and HF in the time to reach a T (re) of 39.5 degrees C (P = 0.205), 38.5 degrees C (P = 0.343) and 37.5 degrees C (P = 0.923) during the immersion. Overall cooling rate for T (re) was also similar between groups (0.23 +/- 0.09 degrees C/min (LF) vs. 0.20 +/- 0.09 degrees C/min (HF), P = 0.647) as well as those for T (es) (P = 0.502) and T (ac) (P = 0.940). Furthermore, mean rate of non-evaporative heat loss (702 +/- 217 W/m(2) (LF) vs. 612 +/- 141 W/m(2) (HF), P = 0.239) was not different between groups. These results suggest that a difference of approximately 10% of body adiposity does not affect core cooling rates in active individuals under 25% body fat rendered hyperthermic by exercise.