Physiological Effects of the Cool Vest Jacket on Recovery after a Repeated Shuttle Sprint Ability Test

Soccer is an intermittent sport requiring rapid recovery from repeated high-intensity efforts, especially under heat stress conditions. Cooling vests have emerged as a practical strategy to enhance post-exercise heat dissipation, yet their physiological effects remain underexplored. This study aimed to assess the efficacy of a cooling vest following a repeated shuttle sprint ability (RSSA) test under hot conditions, focusing on skin temperature, blood lactate, and heart rate responses. Eleven recreational male soccer players completed two RSSA tests in a randomized crossover design, each followed by 15 min of passive recovery with or without a cooling vest. Skin temperature was measured at five anatomical sites, while blood lactate and the heart rate were recorded at baseline, pre-test, and at 0, 1, 3, 5, 10, and 15 min post-exercise. Compared with the control condition, the cooling vest intervention significantly reduced skin temperature at the 3^rd and the 5^th min post-exercise (3 min: d_z = -1.54, 95% CI [-2.53, -0.55], p < 0.001; 5 min: d_z = -0.90, 95% CI [-1.71, -0.08], p = 0.016). Transient between-condition differences were also observed for blood lactate at the 3^rd and the 5^th min (3 min: d_z = -1.00, 95% CI [-1.95, -0.006], p = 0.022; 5 min: d_z = -1.34, 95% CI [-2.36, -0.31], p = 0.003) and for the heart rate at 1 min post-exercise (d_z = -0.84, 95% CI [-1.59, -0.09], p = 0.013). No consistent differences were found at other time points. The protocol showed high between-day reliability (CV = 2.47%; ICC = 0.75), supporting the validity of the observed effects. In conclusion, post-exercise use of a cooling vest after repeated sprints in the heat accelerates early superficial thermal recovery, as evidenced by reductions in skin temperature during the first minutes of recovery. Transient and isolated differences were also observed for the heart rate and blood lactate concentration; however, these effects were not sustained across the full recovery time-course. From a practical perspective, cooling vests may be useful during short recovery windows in intermittent sports, while further research is needed to determine whether broader or longer-lasting physiological benefits can be achieved.