Heat balance and cumulative heat storage during exercise performed in the heat in physically active younger and middle-aged men.

On separate days, eight physically active younger (22 +/- 2 years) and eight highly trained middle-aged (45 +/- 4 years) men matched for physical fitness and body composition performed 90 min of semi-recumbent cycling at a constant rate of heat production (290 W) followed by 60 min of seated recovery in either a temperate (T, 30 degrees C), warm (W, 35 degrees C) or hot (H, 40 degrees C) ambient condition. Rectal temperature (T (re)) was measured continuously, while the rate of whole-body heat loss (H (L)), as well as changes in body heat content (H (b)) was measured simultaneously using direct whole-body and indirect calorimetry. No difference in H (L) was observed between age groups for all ambient conditions.

Heat balance and cumulative heat storage during intermittent bouts of exercise.

Purpose: The aim of this study was to investigate heat balance during thermal transients caused by successive exercise bouts. Whole-body heat loss (H x L) and changes in body heat content (Delta Hb) were measured using simultaneous direct whole-body and indirect calorimetry.

Methods: Ten participants performed three successive bouts of 30-min cycling (Ex1, Ex2, and Ex3) at a constant rate of heat production of approximately 500 W, each separated by 15-min rest (R1, R2, and R3) at 30 degrees C.

Core temperature differences between males and females during intermittent exercise: physical considerations.

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.

The effects of protective clothing on energy consumption during different activities.

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.