Influence Of Post-exercise Nutrient Intake On Recovery And Subsequent Exercise Performance In Youth Cyclists

Abstract

PURPOSE: The purpose of this study was to determine if chocolate milk (CM) consumption after high-intensity cycling affected post-exercise recovery and subsequent exercise performance in youth cyclists, compared to carbohydrate (CHO) and placebo (PL) beverages. METHODS: Eight youth cyclists (15-18 y, VO2peak = 61.8±7.7 mL·kg-1·min-1) completed two exercise sessions on three separate occasions. The first exercise session (EX1) included 30 min of constant-load cycling, and 60 min of standardized high-intensity intervals. Subjects consumed a recovery beverage (PL, CHO or CM) immediately following EX1 and again 2 h after EX1. A standardized lunch was consumed 4 h post-EX1, and a second exercise session (EX2) was completed 7 h after EX1. EX2 consisted of 30 min of constant-load cycling followed by a simulated 30 km time trial (TT). Ratings of muscle soreness, and mental and physical energy/fatigue were obtained prior to EX1, 4 h post-EX1, and pre-EX2. TT power output (W) was used to assess subsequent exercise performance. RESULTS: Changes in muscle soreness over time were not significantly different between treatments. However, soreness was significantly elevated in PL from pre-EX1 (44±23 mm) to 4 h post-EX1 (67±22 mm) and pre-EX2 (68±20 mm). Soreness tended to be elevated in CHO from pre-EX1 (37±26 mm) to 4 h post-EX1 (52±28 mm; p = 0.051) but not at pre-EX2, and soreness was not elevated at any post-exercise timepoint in CM. Physical fatigue ratings increased significantly from pre-EX1 to pre-EX2 in PL, but not CHO or CM. In addition, changes in physical fatigue after exercise tended to be less pronounced with CM versus other treatments (p-values for treatment x time effects: 0.03 - 0.19). Average TT power was similar between PL (181±27 W), CHO (197±39 W) and CM (195±38 W). CONCLUSIONS: CM ingestion after exercise may confer recovery benefits in youth cyclists, as demonstrated by the absence of elevated muscle soreness and fatigue ratings post-exercise. However, significant treatment x time effects were not consistently observed across all soreness/fatigue measurements. Subsequent cycling performance was not significantly different between treatments. However, TT performance effects (~8% higher power in CM/CHO versus PL) may be functionally relevant if upheld in trials with larger sample sizes.