Differences in VO2peak of Surfers when Paddling in Water Versus on a Swimbench Ergometer

Purpose: There are multiple studies in the literature that have assessed the aerobic fitness of both recreational and competitive surfers during simulated paddling on a swimbench ergometer. However, no previous studies have measured oxygen consumption of these athletes while paddling in the water. Therefore, the purpose of this study was to test the hypothesis that surfers will achieve a higher VO2peak when tested in a swim flume versus on a swimbench ergometer. Methods: Forty-eight proficient surfers (Male: 38, Female: 10) between the ages of 18 and 45 years old participated in the study. Protocol one measured heart rate (HR), oxygen consumption (VO2) and respiratory exchange ratio (RER) in 15-second intervals while subjects performed an incremental (1minute stages) paddling test both on a Vasa swimbench ergometer and in an Endless Pool Elite swim flume. The order of exercises modality was randomized between subjects and separated by one week. Protocol two followed the same procedures as protocol one but additionally measured muscle activity and changes in skin temperature. Peak HR, VO2, and RER at volitional fatigue were recorded for each subject for protocol one and two. Muscle activity during the final stage and changes in skin temperature were recorded for protocol two only. A paired t-test was used to determine any differences in VO2peak, HR, RER, peak muscle activity, and changes in skin temperature between the two testing modalities. Results: Participants were 26.4±7.5 years old, 175.13±8.55 cm, 71.01±10.55 kg, and reported 11.63±7.86 years of experience. There were no significant differences in maximal HR (Flume: 177±12 bpm, Ergo: 176±17 bpm) or RER (Flume: 1.23±0.11, Ergo: 1.22±0.10) between the two tests. However, VO2peak was significantly higher in the swim flume (33.03±6.48 ml/kg/min) versus on the swimbench ergometer (29.86±6.76 ml/kg/min) (p-value ˂ 0.001). During the final stage, activation of the upper trapezius was significantly higher in the water and latissimus dorsi activity was significantly higher on the ergometer (p-value 0.05). There was also a significantly greater decrease in skin temperature at the end of testing in the swim flume (p 0.001). Conclusion: Results from this study demonstrate that when tested in a training specific environment, surfers significantly increased their VO2peak by 11%. These differences are likely attributable to differences in muscle recruitment and thermoregulation found between exercise paradigms. These data suggest that previous reports of VO2peak in surfers, as determined by swimbench ergometry, likely underestimated surfer's aerobic fitness. Future research investigating the aerobic fitness of surfers should be done while paddling in water.