Metabolic and cardiovascular responses to exercise with caffeine.
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Biomedical subjects
M M Toner
Publications and source records attributed to M M Toner.
Auxiliary cooling: comparison of air-cooled vs. water-cooled vests in hot-dry and hot-wet environments.
Water-cooled, air-cooled, and ambient air-ventilated auxiliary cooling vests were evaluated in a hot-wet climate (HW) (35 degrees C, 75% R.H.) and a hot-dry environment (HD) with additional infrared radiation (Ta = 49 degrees C, 20% R.H., 68 degrees C black globe temperature). Twelve subjects dressed in full chemical warfare combat uniforms underwent 120 min of heat exposure in each combination of climate and cooling vest, except for the hot-dry environment and ambient-air vest. During each exposure, total exercise time was 20 min and rest time 100 min. This resulted in a mean time weighted metabolic rate of 180 W. Both water-cooled and air-cooled vests were sufficient for cooling in the HW climate: heat storage (delta S) was 13 and 7 W, final rectal temperature (Tre) 37.4 and 37.3 degrees C, and heart rate (HR) 124 and 112 b . min-1, respectively. While using the ambient-air vest, all variables were significantly (p less than 0.05) higher (delta S, 25 W; Tre, 37.7 degrees C; HR, 139 b . min-1; respectively). In the HD climate, both water and air-cooled vests were insufficient with a delta S of 46 and 48 W, final Tre of 38.4 and 38.3 degrees C, and final HR of 151 and 147 b . min-1. However, both cooling vests improved the subjects' physiological status compared to these predicted variables without auxiliary cooling. No significant differences were found between the air or the water-cooled vests in either the HD or HW climates. It was concluded that an air-cooled vest can be used with the same efficiency as a water-cooled vest. In contrast, the ambient-air vest was shown to have a low effectiveness in HW and to be dangerous in a HD climate.
Body Temperature Regulation↗
Modification of the Monark bicycle ergometer for underwater exercise.
A standard Monark bicycle ergometer was modified for underwater exercise by removal of the friction belt and attachment of one to six metal fins to the flywheel. Three fins could be fastened to either side of the flywheel. The fins used on the left side of the wheel were made of standard perforated angle iron with the perpendicular side measuring 38 mm; those on the right side were made from the same length of nonperforated angle iron but with a perpendicular side of only 26 mm. Net surface area of the two types of fins (excluding area of perforation) was the same. Oxygen uptake (VO2) was found to be: VO2 = a(rpm)b + 0.25, 1.min-1, with a = 0.00164 -- 0.00104n + 0.000266n2 -- 0.00002n3; b = 1.64 + 0.506n -- 0.104n2 + 0.00667n3, when n is the number of fins. The correlation coefficient (r) between measured and predicted VO2 was r = 0.98. The preferable range of pedaling speeds was 29-40 rpm to maintain a constant speed for up to 1 h. Major advantages of this modified ergometer for underwater exercise are 1) the modification is simple and the same ergometer can be used for land exercise, 2) the ergometer can be biologically calibrated and used for a wide range of exercise oxygen uptakes, and 3) subjects can perform for a proportionally longer time period than other modifications of the same ergometer.
Adult↗