Comparison of Maximal Oxygen Consumption During Underwater Treadmill Running and Land-Based Treadmill Running

Underwater (UW) running has emerged as a low load bearing form of supplementary training for cardiovascular fitness, as a way to promote recovery from strenuous exercise while maintaining aerobic fitness, and as a way to prevent injury. Prior studies have reported conflicting results as to whether UW treadmill running elicits similar cardiorespiratory responses to land-based (LB) running. PURPOSE: To compare maximal oxygen consumption (max VO2) during 2 UW treadmill trials (one barefoot and one wearing specially designed underwater running shoes) and a LB treadmill trial to exhaustion. METHODS: Experienced male triathletes (n=14) (mean (sd) age, ht and wt = 35.1±9.8 yrs, 182.1±6.1 cm, and 78.7±11.3 kg, respectively) completed max VO2 trials for each of 3 conditions: running on an UW treadmill with water running shoes, running on an UW treadmill barefoot, and running on a LB treadmill. For UW treadmill trials, participants started at a pre-determined moderately-vigorous pace. Speed was increased 0.5 mph each minute for the first 4 minutes and thereafter jet resistance was increased 10% each minute to exhaustion. For LB treadmill trials, participants began at a predetermined moderately-vigorous pace. Grade was increased 2% every 2 minutes to exhaustion. Descriptive statistics and repeated measures ANOVA were calculated. RESULTS: There was no difference in max VO2 among the trials (max VO2 (ml.kg.min) = 53.0±7.0 for the LB trial, 51.8±8.7 for the UW barefoot trial and 53.2±6.8 for the UW shoe trial, p=0.584). RPE, and RER were not significantly different among the trials (p=, 0.698, and 0.075, respectively). For the UW trials, speed, jet resistance, and water temperature were not significantly different between trials (p=0.678, 0.336, and 0.672, respectively). Maximal HR was significantly greater for the LB trial than for the UW trials (HR = 185.1±13.4 for the LB trial, 172.5±12.8 for the UW shoe trial and 172.8±9.7 for the UW barefoot trial, p=.004). CONCLUSIONS: Maximal aerobic capacity can be accurately assessed on an UW treadmill with less cardiovascular strain.