Influence of immersion on respiratory requirements during30-min cycling exercise

Abstract

Influence of immersion on respiratory requirements during 30-min cycling exercise. P-H. Bre Âchat, J-P. Wolf, M-L. Simon-Rigaud, N. Bre Âchat, J-P. Kantelip, S. Berthelay, J. Regnard. #ERS Journals Ltd 1999. ABSTRACT: Immersion is considered to facilitate exercise-based rehabilitation. However, the drag effect of moving limbs in water, likely to increase the respiratory requirements at exercise, is not mentioned in many reports.The energetic and ventilatory requirements of 30 min steady state cycling exercise performed by healthy male subjects in air and during immersion up to the xiphoid in 338C water were compared.In the first experimental series nine subjects exercised at the same 60% maximal oxygen consumption (V 'O 2 ,max) in air and water. In the two ambient conditions, ventilatory variables had similar values, but the ergometric setting had to be reduced during water immersion so that the workload rated only 6920 W (meanSD) in water versus 12132 W (p<0.001) in air. In the second experimental series, the same ergometric work load (122 W) was achieved by nine subjects with an average V 'O 2 of 2,210300 mL . min -1 in air versus 2,868268 mL . min -1 in water (p<0.001). Resting water immersion caused a marked trend for decreasing vital capacity (p=0.06), but no modification of other ventilatory variables. During exercise at similar V 'O 2 , the average values of minute ventilation (V 'E), tidal volume (VT), respiratory frequency (fR), tidal inspiratory time (VT/tI) were not different between water and air. However, at similar ergometric workload, V 'E, VT, fR, VT/tI and plasma lactate levels were significantly higher in water than in air. Such consequences of the drag effect of water upon limb movements have not been reported in previous studies relying on shorter exercise bouts.Thus, maintaining steady exercise levels in water either led to a decrease in the workload or required a 25% higher oxygen consumption than in air. These findings may be relevant to the prescription of water immersion rehabilitation programmes. Eur Respir J 1999; 13: 860±866.

Discussion of “Cardiorespiratory alterations induced by low-intensity exercise performed in water or on land”

“…However, the workload and rpm for the dry-land condition were not indicated by the authors, making difficult to interpret the data by others researchers. Because on the high density of the water, pedaling at a same cadency (rpm) would lead to a higher external output and V O 2 in water as clearly demonstrated in previous studies (Bréchat et al 1999(Bréchat et al , 2013. Regarding hemodynamics variables, the authors demonstrated similar values for stroke volume and cardiac output at a similar percentage of dry-land V O 2peak value, in agreement with the previous work of Bréchat et al (2013).…”

“…Therefore, this could explain why respiratory rate and ventilation were found higher during exercise in water condition (Table 3) (Ayme et al 2015). However, this result is in contradiction with a previous study demonstrating similar respiratory rate and ventilation at 60% of V O 2peak (dry-land condition) (Bréchat et al 1999). We also demonstrated no differences in respiratory rate and ventilation at submaximal and maximal intensities matched with similar external power output (Garzon et al 2012).…”

Aqua jogging-induced pulmonary oedema

“…some degree of suboedema may have been present [4,6]. In addition, 20uC water carries a cold stress, even to an exercising subject [4,7,8], and even mild cooling increases peripheral vascular resistance, left ventricular afterload and pulmonary congestion [7]. Finally, symptoms related to pulmonary oedema occur earlier during sustained exercising in water than on land.…”

“…In an experiment designed to compare immersed versus ground 30-min cycling, thoracic electrical impedance was lower during recovery on land after exercising in water than on ground, which reflected a larger amount of thoracic fluid, while stroke volume was simultaneously lower, i.e. some degree of suboedema may have been present [4,6]. In addition, 20uC water carries a cold stress, even to an exercising subject [4,7,8], and even mild cooling increases peripheral vascular resistance, left ventricular afterload and pulmonary congestion [7].…”

“…Conversely, running or cycling at sustained intensity may lead to higher burden to lung tissue in water than on ground. In water, the exercising mechanical strain [2] is strengthened by congestion of pulmonary vessels (hence, decreased lung compliance) and also by the inspiratory loading due to hydrostatic pressure, which is likely to enlarge intraairway pressure swings [3,4]. In addition, the work of breathing increases progressively during endurance exercise at constant work [5].…”