Pre-sleep Protein Ingestion Increases Mitochondrial Protein Synthesis Rates During Overnight Recovery from Endurance Exercise: A Randomized Controlled Trial

Abstract

Background: Casein protein ingestion prior to sleep has been shown to increase myofibrillar protein synthesis rates during overnight sleep. It remains to be assessed whether pre-sleep protein ingestion can also increase mitochondrial protein synthesis rates. Though it has been suggested that casein protein may be preferred as a pre-sleep protein source, no study has compared the impact of pre-sleep whey versus casein ingestion on overnight muscle protein synthesis rates.

Objective: We aimed to assess the impact of casein and whey protein ingestion prior to sleep on mitochondrial and myofibrillar protein synthesis rates during overnight recovery from a bout of endurance-type exercise.

Methods: Thirty-six healthy young men performed a single bout of endurance-type exercise in the evening (19:45 h). Thirty minutes prior to sleep (23:30 h), participants ingested 45 g of casein protein, 45 g of whey protein, or a non-caloric placebo. Continuous intravenous L-[ring-¹³C₆]-phenylalanine infusions were applied, with blood and muscle tissue samples being collected to assess overnight mitochondrial and myofibrillar protein synthesis rates.

Results: Pooled protein ingestion resulted in greater mitochondrial (0.087 ± 0.020 vs 0.067 ± 0.016%·h^-1, p = 0.005) and myofibrillar (0.060 ± 0.014 vs 0.047 ± 0.011%·h^-1, p = 0.012) protein synthesis rates when compared with placebo. Casein and whey protein ingestion did not differ in their capacity to stimulate mitochondrial (0.082 ± 0.019 vs 0.092 ± 0.020%·h^-1, p = 0.690) and myofibrillar (0.056 ± 0.009 vs 0.064 ± 0.018%·h^-1, p = 0.440) protein synthesis rates.

Conclusions: Protein ingestion prior to sleep increases both mitochondrial and myofibrillar protein synthesis rates during overnight recovery from exercise. The overnight muscle protein synthetic response to whey and casein protein does not differ.

Clinical trial registration: NTR7251 .

Fig. 1

Experimental protocol. A carbohydrate drink was consumed immediately following a bout of endurance-type exercise at 20:45 h. Participants were randomly assigned to ingest placebo, 45 g of casein protein, or 45 g of whey protein at 23:30 h

Fig. 2

Overnight plasma glucose (a) and insulin (b) levels following pre-sleep placebo (PLA), casein protein (CAS), or whey protein (WHEY) ingestion. Data are analyzed by two-factor repeated-measures analysis of variance with time as the within-subject factor and treatments as the between-subject factor. The data are expressed as mean ± standard deviation. Time × treatment: panel a: p = 0.298, panel b: p < 0.001. ^CPCAS significantly higher than PLA. ^WPWHEY significantly higher than PLA. ^WCWHEY significantly higher than CAS, p < 0.05

Fig. 3

Overnight plasma levels and incremental area under the curve (iAUC) of phenylalanine (a, b, leucine (c, d), essential amino acid (e, f), and total amino acid levels (g, h) following pre-sleep placebo (PLA), casein protein (CAS), or whey protein (WHEY) ingestion. Timeline data are analyzed by two-factor repeated-measures analysis of variance with time as the within-subject factor and treatments as the between-subject factor. Timeline data are expressed as mean ± standard deviation. Incremental area under the curve data are analyzed with a one-way analysis of variance. Incremental area under the curve data are expressed as box-and-whisker plots with the median (line), mean (cross), interquartile range (box), and minimum and maximum values (tails). Time × treatment: panels a, c, e, g: p < 0.001. Analysis of variance: panels b, d, f, h: p < 0.001. ^CP: CAS significantly higher than PLA. ^WPWHEY significantly higher than PLA. ^WCWHEY significantly higher than CAS. iAUC data: treatments without a common letter differ, p < 0.05

Fig. 4

Overnight plasma l-[ring-¹³C₆]-phenylalanine enrichments following pre-sleep placebo (PLA), casein protein (CAS), or whey protein (WHEY) ingestion. Data are analyzed by two-factor repeated-measures analysis of variance with time as the within-subject factor and treatments as the between-subject factor. The data are expressed as mean ± standard deviation. Time × treatment: p < 0.001. ^PWPLA significantly higher than WHEY. ^CWCAS significantly higher than WHEY, p < 0.05. MPE mole percent excess

Fig. 5

Overnight myofibrillar (a) and mitochondrial (b) protein synthesis rates following pre-sleep placebo (PLA), casein protein (CAS), or whey protein (WHEY) ingestion. The data are presented as box-and-whisker plots with the median (line), mean (cross), interquartile range (box), and minimum and maximum values (tails). Data were analyzed with a one-way analysis of variance with treatment as the between-subject factor and a Bonferroni correction was applied. Analysis of variance: panel a: p = 0.015, panel b: p = 0.009. Treatments without a common letter differ, p < 0.05. FSR fractional synthetic rate

Fig. 6

Myosin IIa (MHC IIa) and citrate synthase (CS) protein abundance in myofibrillar (Myofib) and mitochondrial (Mito) protein fractions (a), equal amount of protein loaded on the gel was confirmed by staining the SDS-page gel (b). CBB coomassie brilliant blue