Vertical Ground Reaction Force During a Water-Based Exercise Performed by Elderly Women: Equipment Use Effects

Purpose: The present study aimed to compare the vertical ground reaction force responses during the performance of the stationary running water-based exercise with and without equipment at different cadences by elderly women. Method: Nineteen elderly women (age: 68.6 ± 5.0 years; body mass: 69.0 ± 9.5 kg; height: 154.9 ± 5.6 cm) completed one session consisting of the performance of the water-based stationary running with elbow flexion and extension immersed to the xiphoid process depth. The exercise was performed in three conditions, without equipment, with water-floating and with water-resistance equipment, at three cadences (80 b·min^-1, 100 b·min^-1 and maximal) in a randomized order. Peak and impulse of vertical ground reaction force were collected during the exercise using an underwater force plate. Repeated measures two-way ANOVA was used (α = 0.05). Results: Peak vertical ground reaction force (p < .001) and impulse (p ≤ 0.002) resulted in lower values for the water-floating use (0.42-0.48 BW and 0.07-0.13 N.s/BW) in comparison to the water-resistance equipment use (0.46-0.60 BW and 0.09-0.16 N.s/BW) and to the non-use of equipment (0.45-0.60 BW and 0.07-0.17 N.s/BW), except for the impulse at the maximal cadence. In addition, peak vertical ground reaction force at 80 b·min^-1 (p = .002) and impulse at the maximal cadence (p < .001) showed lower values compared to the other cadences. Conclusion: The use of water-floating equipment minimizes the vertical ground reaction force during the stationary running water-based exercise performed by elderly women regardless of the cadence.