M. Fisher, L. D’Acquisto, D. D’Acquisto, K. Roemer, J. Tesfaye, M. Dohrman, L. Miller

Central Washington University, Ellensburg, WA

Systematically regulating intensity while exercising in water is problematic given the nature of the workout medium. One approach to controlling exercise intensity is self-regulation by instructing participants to exercise over a range of prescribed rating of perceived exertions (e.g. RPE, Borg 6-20 scale). PURPOSE: This study investigated the cardiorespiratory responses to a series of incremental, perceptually self-regulated shallow water exercise (SR-SWE) efforts. It was hypothesized that (1) a steady rate cardiorespiratory response (oxygen uptake (V̇O2)& heart rate (HR)) for sustained SR-SWE efforts prescribed at RPE 9, 11, 13, 15 and 17 would be achieved, and (2) V̇O2 would be linearly, positively and strongly related to prescribed perceived exertions ranging from RPE 9 to 17. METHODS: Male volunteers (n=6, 23±1 years) participated in a familiarization session and a second testing period in which they performed five, five min SR-SWE efforts prescribed at RPE 9, 11, 13, 15, and 17. In addition, participants performed an incremental, five min SR-SWE bout to a max of RPE 20 to determine peak V̇O2 and HR. V̇O2 (Parvo-Medics TrueMax 2400, indirect calorimetry), HR (Polar, telemetry) and blood lactate (BLa) concentration (Analox Instruments) were measured for all SR-SWE efforts. Participants were immersed to axillary level (~75% of stature; water temperature, ~28-290 Celsius) for all exercise efforts. RESULTS: Peak V̇O2, HR, respiratory exchange ratio, and BLa was 3.63±0.25 l·min-1, 187±6 b·min-1, 1.08±0.03, and 11.7±1.2 mM, respectively. For RPE efforts 9, 11, 13, 15 & 17, both V̇O2 and HR for mins two through five were the same (P>0.05). Steady rate V̇O2 and HR, and BLa ranged from 0.69±0.10 l·min-1, 83±5.8 b·min-1, 1.53±0.6 mM (RPE 9, “very light”) to 3.10±0.471 l·min-1, 168±7 b·min-1, and 6.4±1.5 mM (RPE 17, “very hard”), respectively (P<0.05). Percent V̇O2 and %HR peak increased in a step-wise fashion from RPE 9 (19.0±2.0 and 44.3±2.7%) to RPE 17 (85.1±7.4 and 90.4±2.5%, respectively) (P<0.05). V̇O2 and HR were linearly and strongly correlated with RPE (R ranged from 0.94 to 0.99, p<0.05). CONCLUSION: Self-regulation of intensity based on prescribed RPE is a viable way of regulating intensity while exercising in a shallow water medium.

Supported by CWU-Ellensburg Master's Research or Creative Activity Fellowship.

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