J. M. Cacchillo, K. K. Lahue, K. L. Johnson, M.B. Hope, and W. M. Silvers

Whitworth University, Spokane, WA

Expected exercise duration has been shown to affect pacing strategies and ratings of perceived exertion. PURPOSE: To observe the effect of knowledge of exercise duration on: 1) rate of perceived exertion (RPE), 2) heart rate, 3) pacing strategy during a timed circuit workout. METHODS: Sixteen college-age, recreationally-active participants (nmale = 9, nfemale = 7) completed two separate 8-min circuit workouts: one of known duration (KD) and one of unknown duration (UD) in a randomized, crossover design. Each participant completed as many cycles as possible for a four exercise circuit: 200-m run, 10 walking lunges with 15-lb dumbbells, 20 roman twists with a 10-lb medicine ball, and 10 box jumps. Pacing strategy was measured as the total completed cycles during each 8-min workout. Completed cycles were recorded as whole numbers for full cycles plus 0.25, 0.50, or 0.75 depending on the last exercise completed in the final cycle. Heart rate (HR) and rating of perceived exertion (RPE) were collected every two minutes during the workouts. Heart rate was measured using a Polar T31 chest strap with watch and RPE was measured using a Borg 10-point RPE scale. Immediately after each workout, participants provided an RPE value correspondent to the whole workout. RESULTS: Dependent group t-tests were used to determine whether significant differences existed between KD and UD for RPE, HR, and completed circuit cycles. Statistical significance was set at p ≤ 0.05. HR was not significantly different (p=0.07) between UD (177.6 ± 7.5-bpm) and KD (180.4 ± 7.0-bpm). RPE was not significantly different (p=0.89) between UD (5.8 ± 1.2) and KD (5.9 ± 1.3). The number of completed cycles was not significantly different (p=0.42) between UD (3.4 ± 0.5) and KD (3.5 ± 0.5). CONCLUSIONS: A possible reason for the lack of statistical differences in workout pacing, RPE, HR may have been due to the short duration (8-min) of the workout sessions; longer sessions may have elicited a more pronounced effect on these variables. Nevertheless, in this research scenario, knowledge of exercise duration did not significantly affect HR, RPE or workout pacing during an 8-min circuit workout.

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