Effects of Water Immersion on the Internal Power of Cycling

Abstract

Purpose Water immersion adds additional drag and metabolic demand for limb movement with respect to air, but its effect on the internal metabolic power ( Ė int ) of cycling is unknown. We aimed at quantifying the increase in Ė int during underwater cycling with respect to dry conditions at different pedaling rates. Methods Twelve healthy subjects (four women) pedaled on a waterproof cycle ergometer in an experimental pool that was either empty (DRY) or filled with tap water at 30.8°C ± 0.6°C (WET). Four different pedal cadences ( f p ) were studied (40, 50, 60, and 70 rpm) at 25, 50, 75, and 100 W. The metabolic power at steady state was measured via open circuit respirometry, and Ė int was calculated as the metabolic power extrapolated for 0 W. Results The Ė int was significantly higher in WET than in DRY at 50, 60, and 70 rpm (81 ± 31 vs 32 ± 30 W, 167 ± 35 vs 50 ± 29 W, 311 ± 51 vs 81 ± 30 W, respectively, all P < 0.0001), but not at 40 rpm (16 ± 5 vs 11 ± 17 W, P > 0.99). Ė int increased with the third power of f p both in WET and DRY ( R 2 = 0.49 and 0.91, respectively). Conclusions Water drag increased Ė int , although limbs unloading via the Archimedes’ principle and limbs shape could be potential confounding factors. A simple formula was developed to predict the increase in mechanical power in dry conditions needed to match the rate of energy expenditure during underwater cycling: 44 f p 3 – 7 W, where f p is expressed in Hertz.

Water-Based Rehabilitation in the Elderly: Data Science Approach to Support the Conduction of a Scoping Review

“…This property allows a reduction in body weight in patients under particular conditions. For example, after surgery or in case of strength deficit, the water allows passive and active movements during rehabilitation, reducing the impact of gravity [3]. In a similar way, the same hydrostatic thrust guarantees a safe environment for the patients, preventing the risks of a trauma related to an accidental fall during the exercises.…”

Effectiveness of aquatic exercise versus other therapeutic modalities in patients with knee osteoarthritis pain: A systematic review with meta-analysis

“…Its main bene ts for therapeutic strategies come from Archimedes' principle, which determines that a body partially or totally submerged in water is pushed upwards with a force of equal magnitude to the uid displaced by it [5].…”