Water-based exercises in pregnancy: Apparent weight in immersion and ground reaction force at third trimester.

Background: The morphological alterations during pregnancy may affect the biomechanical loads during exercise practice. Aquatic exercises may suit pregnant women, who are recommended to exercise with low vertical ground reaction force loads. Therefore, the study aimed to determine the apparent weight reduction during immersion and the vertical ground reaction force of three specific water-based exercises in pregnant women at the third trimester.
Methods: Eleven pregnant women volunteered to take part in the study [32.0 (SD 1.3) weeks, 28.1 (SD 5.7) years, 72.5 (SD 10.1) kg]. The protocol started with the participants immersed to the xiphoid process depth for the apparent weight assessment. Then, three water-based exercises (stationary running, frontal kick and butt kick) were randomly performed at a pre-selected cadence, with 5-min interval. The vertical ground reaction force was measured in each exercise and peak, impulse, contact time and swing time were determined. Repeated measures ANOVA was used (α = 0.05).
Findings: The apparent weight reduction resulted a mean of 82.9 (SD 6.5)% of body weight. Peak, impulse, contact time and swing time revealed no significant difference between exercises (P > 0.05). Values of peak of vertical ground reaction force ranged from 0.67 to 0.72 units of body weight.
Interpretation: Pregnant women at the third trimester can benefit from the apparent weight reduction during immersion for exercising. The three water-based exercises presented similar vertical ground reaction force values, which are considered as low odds for musculoskeletal injuries. Therefore, these findings highlight the safety of the water-based exercise program during pregnancy.
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