Impact of Pedaling Cadence and Resistance on the Cardiovascular Response during Underwater Cycling

• Published in: The FASEB journal Vol. 35; no. S1
• Main Authors: Fukuie, Marina, Hoshi, Daisuke, Hashitomi, Tatsuya, Watanabe, Kouichi, Tarumi, Takashi, Sugawara, Jun
• Format: Journal Article
• Language: English
• Published: The Federation of American Societies for Experimental Biology 01-05-2021
• ISSN: 0892-6638; 1530-6860
• DOI: 10.1096/fasebj.2021.35.S1.00383

The cardiovascular response to underwater cycling has not been studied in detail previously. The purpose of this study was to investigate the impact of change in pedaling cadence and resistance on cardiovascular measurements during underwater cycling.
Eleven healthy young men (24±2 yrs) performed 15 minutes of underwater cycling with load (LC) and no‐load (NLC) conditions. In both conditions, after a 4 minute seated rest, 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 to increase water resistance against pedaling. Oxygen uptake (VO2), finger blood pressure (BP), heart rate (HR), stroke volume (SV), and cardiac output (CO) were continuously measured during cycling.
VO2 increased with higher cadences in both conditions (NLC: 3.09±0.03 ml/kg/min at rest to 9.71±0.18 ml/kg/min at 60 rpm, LC: 3.10±0.04 ml/kg/min at rest to 16.90±0.18 ml/kg/min at 60 rpm) along with increases in HR and CO. HR was greater in LC than NLC at all cadences (all P<0.05). CO at 60 rpm was also higher in LC than NCL (14.1±0.4 vs. 8.6±0.3 l/min, P<0.001), although it was similar at rest, 30 rpm, and 45 rpm between LC and NLC. In both conditions, SV was not different between rest and 30 rpm but began to increase after 45 rpm. At 60 rpm, SV increased only in the LC and was higher than NLC (LC vs. NLC: 129±3 vs. 100±2 ml, P=0.01). Systolic BP and pulse pressure were not different between both conditions at rest and 45 rpm but increased at 60 rpm and was higher in LC than NLC. Diastolic and mean BP did not change in either condition.
Our results suggest that pedaling cadence and resistance both have significant impact on the cardiovascular response during underwater cycling which may be affected by change in hydrostatic pressure, frequency of muscle pump, and/or cardiac filling time.