Biomechanical and Physiological Responses during Running in Water and on Dry Land at Maximal Effort

Abstract

PURPOSE: To investigate biomechanical and physiological responses during running in water (i.e., deep water running: DWR) and treadmill running on dry land (TMR) at maximal effort. METHODS: Eleven subjects (22.6 ± 2.6 years) performed DWR and TMR graded exercise tests on separate days. On the third test day, the subjects exercised at their 60%, 80%, and 100% of maximal oxygen uptake (VO2max). VO2max, maximal heart rate (HRmax), and rating of perceived exertion at maximal effort (RPE max) were measured during graded exercise tests, as was stride frequency (SF) of each stage of the graded exercise tests. Muscle activity from the rectus femoris, biceps femoris, tibialis anterior, and gastrocnemius were measured. Maximal physiological responses (i.e., VO2max and HRmax) and RPEmax were analyzed using a Student’s t-test (α = 0.05). Muscle activity and SF were analyzed using a 2 (mode) x 3 (intensity) repeated measures analysis of variance. When an interaction effect was observed, Bonferroni’s post hoc tests were conducted to compare the mean values (α = 0.05). RESULTS: VO2max (TMR: 59.2 ± 5.6 ml/kg/min, DWR: 48.9 ± 5.7 ml/kg/min) nor HRmax (TMR: 191.2 ± 6.9 beats/min, DWR: 174.1 ± 9.6 beats/min) were different between DWR and TMR (P<0.001). RPEmax was not different between DWR and TMR (TMR: 18.4 ± 1.3, DWR: 17.8 ± 1.9: P>0.05). SF was influenced by the interaction of mode and intensity (P<0.001). The SF during DWR was significantly lower than that of TMR for all exercise intensity conditions with SF increasing over intensity at a greater rate during DWR vs. TMR. Muscle activity from all the tested muscles were not influenced by the interaction of mode and intensity (P>0.05). Muscle activity from all the tested muscles were different between modes (P<0.05) and between intensities (P<0.001). Specifically, muscle activity from the lower extremity during DWR was approximately 35% to 69% lower than that of TMR at maximal effort. CONCLUSION: Maximal effort was achieved during DWR and TMR such that muscle activity was lower during DWR vs. TMR. This may explain decreased physiological responses during DWR vs. TMR. Supported by a Grant-in-Aid for Young Scientists (B) from the Japan Society for the Promotion of Science (grant No. 24700758).