Influence Of Different Exercise Intensities On The Respiratory Function And Breathing Pattern During Underwater Cycling

Abstract

Aquatic cycling is gaining a popularity and its physiological responses have been studied in previous research. Exercise intensity during aquatic cycling can be adjusted by changing the cadence and water resistance offered by the paddles on the pedaling mechanism. However, it remains unclear what level of exercise intensity would have a positive effect on the respiratory function. PURPOSE: he purpose of this study was to investigate the association between exercise intensity during aquatic cycling and respiratory function. METHODS: Twelve healthy men performed 15 minutes of aquatic cycling with load (LC) and no load (NLC) conditions. In both conditions, after sitting rest in water for 4 minutes, participants began cycling at 30 rpm, and the cadence was increased 15 rpm every 5 minutes. In LC, 3 paddles were attached to the wheel of stationary bicycle to increase water resistance against pedals. Using a spirometry, respiratory function and respiratory muscle pressure were measured before and after exercise. Breathing pattern was measured by an expiratory gas analyzer during exercise. RESULTS: During aquatic cycling, oxygen uptake (VO2) was significantly higher in LC than NLC (all p < 0.05) and progressively increased from 30 rpm to, 45 and, 60 rpm in both LC and NLC (all p < 0.05). At 60 rpm, respiratory rate was significantly higher (27 ± 3 vs. 23 ± 3 bpm, p < 0.05) and total breathing time, inspiratory time, and expiratory time were significantly lower in LC than NLC (2.3 ± 0.3 vs. 2.7 ± 0.4 sec, 1.0 ± 0.1 vs. 1.2 ± 0.1 sec, 1.3 ± 0.2 vs. 1.5 ± 0.2 sec, respectively, all p < 0.05). While inspiratory volume was significantly higher at 45 and, 60 rpm (855 ± 63 vs. 698 ± 66 ml, 1242 ± 107 vs. 896 ± 84 ml, all p < 0.05), expiratory volume was significantly higher at 30, 45, and 60 rpm (621 ± 76 vs. 576 ± 58 ml, 833 ± 63 vs. 692 ± 67 ml, 1225 ± 105 vs. 884 ± 76 ml, all p < 0.05) in LC than NLC. CONCLUSIONS: These results suggest that inspiratory and expiratory volumes progressively increase with higher cadence during aquatic cycling. But, inspiratory and expiratory times may not change until a higher intensity. Therefore, respiratory muscles may be recruited with increased ventilatory demand in LC compared with NLC.