The ability of energy recovery in professional soccer players is increased by individualized low-intensity exercise

The aim of this study was to investigate whether individualized low-intensity exercise (ILIE) within the recovery domain before lactate threshold 1 (LT 1) improves energetic recovery and general endurance capacity in professional soccer players. Twenty-four professional soccer players (age: 24.53 ± 4.85 years, height: 180 ± 6.30 cm, body mass: 75.86 ± 8.01 kg, body fat: 12.19 ± 2.69%) participated in the study (n = 24). The 1-h ILIE intervention involved 27 jogging sessions spanning nine weeks and jogging speed corresponding to 72% of LT 1 (7.15 ± 0.95 km∙h-1). Pre-ILIE and post-ILIE LT testing variables measured within 9 weeks included blood lactate concentrations (La-) and heart rate (HR) at specific exercise intensities during ILIE LT test. The jogging/running speeds (S), delta (Δ) S, HR, and ΔHR were measured at 1.5, 2.0, 3.0, and 4.0 mmol∙L-1 La-, respectively. Values of La- and HR at the same exercise intensities (5.4-16.2 km∙h-1) in the post-ILIE LT test compared with pre-ILIE LT test were significantly decreased (P < 0.05 and P < 0.01, respectively). Furthermore, S at all specific La- levels (1.5, 2.0, 3.0, and 4.0) were significantly increased, while HR at 2.0, 3.0, and 4.0 La- decreased significantly (P < 0.05 and P < 0.01, respectively). Low to moderate positive correlations were observed between ΔS and ΔHR at 1.5 and 2.0 La- (r = 0.52 and r = 0.40, respectively). The nine-week ILIE improved energy recovery and general endurance of professional soccer players. This relates to repeated high-intensity intermittent sprints during the 90-min soccer game.