Abstract
Background: Swimming subjects the human body to frequent short intervals of breath hold (BH) and resistive forces of water, increased respiratory effort and thermal stress due to immersion in water. This activity demands higher energy expenditure for movement in a viscous medium. To cope with these, certain adaptations occur in cardiovascular and respiratory systems.

Aims and Objectives: Our study compared some cardiovascular and respiratory parameters in male swimmers and sedentary controls at rest and at breakpoint of BH. This helped to know whether respiratory system and cardiovascular system are susceptible to adaptation induced by swimming.

Materials and Methods: Thirty regular swimmers and 30 sedentary healthy controls were considered for investigations. A portable electrocardiograph (ECG), finger-tip pulse oximeter, spirometer, and sphygmomanometer were used to record ECG (PR interval, QRS interval, QTc interval, and QRS axis), SpO2, heart rate (HR), tidal volume (TV), and blood pressure.

Results: In controls, at breakpoint of BH, oxygen desaturation was extremely significant (“P” < 0.0001), TV was extremely significantly increased (“P” = 0.0006), and only within controls group, HR showed significant increase (“P” = 0.04). No statistically significant change in blood pressure was observed between the groups at breakpoint. A significant increase in TV at breakpoint of BH over that of resting value was observed in controls compared to swimmers (“P” = 0.0134). ECG changes in swimmers and controls were not significantly different.

Conclusion: Regular swimming causes oxygen conserving effect, an efficient rise in TV in response to BH.

Key words: Breath-hold; Swimmers; Desaturation; Electrocardiograph; Tidal Volume