Swimming Compared to Cold for Eliciting Maximal Oxygen Uptake in Mice 1

Abstract

Summary

Exposure of mice to water of either 28 or 20° stimulated in about 2 min a maximal oxygen consumption value (12–130 ml/kg/min) similar to swimming in thermoneutral (36°) water. 20° water was considered an excessive stress because of a relatively rapid decline in rectal temperature of 1.2°/min which resulted in metabolic depression. Respiratory exchange ratios during stress in 21% O₂ averaged 0.94 suggesting submaximal loads on the aerobic system. During the additional stress of hypoxia (12% O₂) R rose above 1.00 possibly indicating a true maximal aerobic stress. The ability of these tests to detect aerobic defects was demonstrated by the 26% lower VR _{O2 max} in mice breathing 12% O₂ during stress as compared to those in 21% O₂. It seems both the swimming and cold stress tests may be used interchangeably. Each is of short duration and neither require training.

The authors thank Mr. Joseph F. Pitt for his assistance.