Is Low-Frequency Electrical Stimulation a Tool for Recovery after a Water Rescue? A Cross-Over Study with Lifeguards

This study aimed to evaluate the degree to which transcutaneous electrical stimulation (ES) enhanced recovery following a simulated water rescue. Twenty-six lifeguards participated in this study. The rescue consisted of swimming 100 m with fins and rescue-tube: 50 m swim approach and 50 m tow-in a simulated victim. Blood lactate clearance, rated perceived effort (RPE), and muscle contractile properties were evaluated at baseline, after the water rescue, and after ES or passive-recovery control condition (PR) protocol. Tensiomiography, RPE, and blood lactate basal levels indicated equivalence between both groups. There was no change in tensiomiography from pre to post-recovery and no difference between recovery protocols. Overall-RPE, legs-RPE and arms-RPE after ES (mean +/- SD; 2.7 +/- 1.53, 2.65 +/- 1.66, and 2.30 +/- 1.84, respectively) were moderately lower than after PR (3.57 +/- 2.4, 3.71 +/- 2.43, and 3.29 +/- 1.79, respectively) (p= 0.016,p= 0.010,p= 0.028, respectively). There was a significantly lower blood lactate level after recovery in ES than in PR (mean +/- SD; 4.77 +/- 1.86 mmol center dot L(-1)vs. 6.27 +/- 3.69 mmol center dot L-1;p= 0.045). Low-frequency ES immediately after a water rescue is an effective recovery strategy to clear out blood lactate concentration.