Laboratory 3

Exercise-Induced Heat Stress, Hyperthermia, Dehydration, and Cardiovascular Function

Pur pose:

Exercise in any environment is a source of metabolic heat production.  Exercise in a hot and/or humid environment adds to the heat stress of the body.  An important first step in recognizing the potential dangers of heat stress is to comprehend the magnitude of heat production during different intensities of exercise.  The purpose of this lab is to measure changes in heart rate, oxygen consumption, and core and skin temperatures during 90 min of continuous exercise.

Procedures:

1) One subject will exercise for 90 min while walking briskly up a moderate slope (determine this prior to data collection).

2) Expired air samples will be collected for 1 min minute at minutes 4, 19, 39, and 59.

3) Record heart rates form a polar heart rate monitor every 5 min.

4) Record rectal and skin (chest, upper arm, thigh, calf) temperatures every 10 min.

5) Make sure you measure pre- and post body weight.

 Results:

1) Calculate mean skin temperatures using the equation of Ramanathan et al.

2) Calculate total body temperatures.

3) Calculate body heat storage.

4) Calculate heat production from the exercise VO2 and RER data.

5) Estimate heat loss, and comment on the weight loss from the exercise.

6) Graph the changes in the main IV's you measured.

Discussion:

Did all changes support past research?

At what core temperatures do researchers typically terminate exercise tests of heat stress in research?

Why does exercise VO2 increase during exercise in the heat at a given intensity?

If this subject has a VO2max=3.5 L/min, how much more intense was the exercise at 90 min compared to 5 min?

References

Use the articles posted to readings section for this topic.