Exercise intensity of head-out water-based activities (water fitness)

The aims of this study were: (i) to measure the exercise intensity (EI) of the most common water-based exercises (WE) at different movement frequencies (f1 = 1.8-2.0 Hz; f2 = 2.0-2.2 Hz; f3 = 2.2-2.4 Hz) and at a standardize movement's amplitude; (ii) to measure EI during a combination (MIX) of these WE. Five WE were selected: "running raising the knees high" (S); "jumping moving the legs sideways" (SJ); "jumping moving the legs backward and forward" (FJ); "alternate forward kicks" (FK); "alternate sideways kicks" (SK). Twelve physically active women were asked to perform these WE at the three frequencies, as well as a combination (MIX) of the WE. EI increased significantly (p < 0.01) with increasing frequency; as an average, for all WE: VO2 ranged from 18 to 25 ml kg(-1) min(-1), HR from 102 to 138 bpm, RPE from 9.8 to 14.4 (at f1 and f3, respectively). In terms of % VO2max, EI ranged from 37 to 54% for S, was similar for SJ and FJ (31-43%) and for FK and SK (47-63%) at f1 and f3, respectively. Thus, a given EI can be attained either by changing the type of exercise and/or the frequency of the movement. The combination of exercises did not change (in terms of VO2, HR and RPE) the intensity of each exercise performed separately. These data can be utilized to control, in terms of exercise type and frequency, the intensity of a proposed water-based activity.