The purpose of the present study was to assess the acute effects of pre-sleep consumption of isocaloric casein protein (CP), CP and whey protein (BLEND), or non-caloric control (CTRL) at a dose relative to lean body mass (LBM) on recovery following an evening lower-body resistance exercise (RE) bout. Fifteen active and previously resistance-trained males (age: 21 ± 1 years, body fat: 14.2 ± 2.7%) participated in this randomized, single-blind, crossover study. Participants performed an evening lower-body RE bout and were provided with 0.4 g/kg/LBM of whey protein (WP) supplement post-RE. A single dose of 0.6 g/kg/LBM of CP, 0.4 g/kg/LBM of CP and 0.2 g/kg/LBM WP (BLEND), or CTRL was consumed 30 min prior to sleep. Measurements of perceived recovery (visual analogue scales (VAS) for recovery, soreness, and fatigue), appetite (VAS for hunger, satiety, and desire to eat), as well as pressure-pain threshold (dolorimeter), average power, and peak torque (isokinetic dynamometry) of the right thigh muscles were assessed the following morning. Main effects of time were seen for all recovery variables (perceived recovery: F2,28 = 96.753, p < 0.001, hp2 = 0.874; perceived fatigue: F2,28 = 76.775, p < 0.001; hp2 = 0.846; perceived soreness: F2,28 = 111.967, p < 0.001; hp2 = 0.889). A main effect of supplement was only seen for perceived recovery (F2,28 = 4.869; p = 0.015; hp2 = 0.258), with recovery being 6.10 ± 2.58 mm greater in CP vs. BLEND (p = 0.033) and 7.51 ± 2.28 mm greater in CP than CTRL (p = 0.005). No main effects of supplement were seen in measures of perceived soreness, or fatigue (F2,28 ≤ 2.291; p > 0.120; hp2 ≤ 0.141). No differences between supplements were found in perceived next-morning hunger (p = 0.06), satiety (p ≥ 0.227), or desire to eat (p = 0.528). Main effects of supplement were seen between BLEND and CP vs. CTRL for measures of pain-pressure threshold at the rectus femoris (F2,28 = 9.377; p = 0.001; hp2 = 0.401), the vastus lateralis (F2,28 = 10.887; p < 0.001; hp2 = 0.437), and the vastus medialis (F2,28 = 12.113, p < 0.001; hp2 = 0.464). Values of peak torque and average power were similar between all supplement groups at 60°/sec (F1.309,18.327 ≤ 1.994; p ≥ 0.173; hp2 ≤ 0.125), 180°/s (F2,28 ≤ 1.221; p ≥ 0.310; hp2 ≤ 0.080), and 300°/sec (F2,28 ≤ 2.854; p ≥ 0.074; hp2 ≤ 0.169). Pre-sleep consumption of CP and BLEND at a dose relative to LBM may enhance perceived overnight recovery to a greater extent than CTRL as a result of less muscle soreness the following morning after an acute evening RE bout.
Keywords: appetite; pre-sleep protein; recovery; resistance exercise; supplement.