Pre-sleep protein has been shown to improve overnight muscle protein synthesis, muscle size and strength, and muscle recovery. However, all pre-sleep protein studies to date have utilized dairy-based protein sources. There is currently a large interest in alternative protein sources, such as plant-based protein. Yet, there is no evidence regarding the efficacy of plant-based proteins consumed pre-sleep. PURPOSE: Therefore, the purpose of this study was to compare animal-based vs. plant-based pre-sleep protein on muscle recovery as measured by blood markers of muscle damage and inflammation, metabolism, and muscle function. METHODS: Twenty-seven males performed a bout of eccentric exercise (ECC) for the knee extensors (ext) and flexors (flex) in the morning, then consumed 40 g of either whey hydrolysate (WH, n = 9), whey isolate (WI, n = 6), rice and pea combination (RP, n = 6), or placebo (PL, n = 6) 30 min pre-sleep. The ECC protocol consisted of 5 sets of 15 repetitions of maximal eccentric voluntary contractions for ext and flex of each leg, respectively. Catered meals (15% PRO, 55% CHO, 30% Fat) were provided to participants two days pre-ECC, the day of ECC, and the following two days during follow-up testing to standardized nutrition. Plasma creatine kinase (CK), interleukin-6 (IL-6), interleukin-10 (IL-10), and C-reactive protein (CRP) was measure at pre, post, +4, +6, +24, +48, and +72-hrs post-ECC. Isometric and isokinetic maximal voluntary contraction (ISOM and ISOK, respectively) was measured at pre, post, +24, +48, and +72-hrs post-ECC. Subjective muscle soreness, thigh circumference, and HOMA-IR was measured at pre, +24, +48, and +72-hrs post-ECC. RESULTS: CK increased at +4-hrs post-ECC and remained elevated at all time points compared to baseline (n = 25, p < 0.001) and was significantly greater at +72-hrs compared to all other time points (p < 0.001). IL-6 increased at +6-hrs (n = 25, p = 0.002) with no other time differing from baseline. CRP increased immediately post-ECC (n = 25, p = 0.035) with no other time differing from baseline. There were no group x time interactions for any blood marker. ISOMext was reduced after ECC (p = 0.001) and remained reduced until returning to baseline at +72 hrs. ISOMflex was reduced after ECC and remained reduced at +72-hrs (p < 0.001). ISOK60ext and ISOK60flex were reduced after ECC and remained reduced at +72-hrs (p < 0.001). ISOK180ext and ISOK180flex were reduced after ECC and remained reduced at +72-hrs (p < 0.05). ISOK300ext was reduced after ECC (p < 0.05) and remained reduced until returning to baseline at +72 hrs. ISOK300flex was reduced at +24-hrs and remained reduced at +72-hrs (p < 0.05). There were no group x time interactions for any muscle function marker. Muscle soreness increased post-ECC (p < 0.001) and did not return to baseline. There were no group x time interactions for muscle soreness. Thigh circumference (p = 0.456) and HOMA-IR (p = 0.396) did not change post-ECC. IL-10 concentrations were below the valid detectable limits of the assay used, thus were not included in the analyses. CONCLUSIONS: These data suggest that middle-aged men consuming 1.08 ± 0.02 g/kg/day PRO did not recover well from damaging exercise at +72-hrs and that pre-sleep protein, regardless of source, did not aid in muscle recovery when damaging exercise was performed in the morning. PRACTICAL APPLICATION: Individuals should consume a sufficient bolus of high-quality protein in close proximity to their exercise session, whenever that session may be. Further, pre-sleep protein consumption can be utilized to consume enough protein throughout the day.
