Abstract

INTRODUCTION:

The role of nutrition in modulating post-exercise overnight recovery remains to be elucidated. We assessed the impact of protein ingestion immediately prior to sleep on digestion and absorption kinetics and protein metabolism during overnight recovery from a single bout of resistance type exercise.

METHODS:

16 healthy young males performed a single bout of resistance type exercise in the evening (20:00) after a full day of dietary standardization. All subjects were provided with appropriate recovery nutrition (20 g protein, 60 g carbohydrate) immediately after exercise (21:00). Thereafter, 30 min prior to sleep (23:30 h) subjects ingested a beverage with (PRO) or without (PLA) 40 g specifically produced intrinsically [1-C]phenylalanine labeled casein protein. Continuous intravenous infusions with [ring-H5]phenylalanine and [ring-H2]tyrosine were applied with blood and muscle samples collected to assess protein digestion and absorption kinetics, whole-body protein balance and mixed muscle protein synthesis rates throughout the night (7.5 h).

RESULTS:

During sleep casein protein was effectively digested and absorbed resulting in a rapid rise in circulating amino acid levels which were sustained throughout the remainder of the night. Protein ingestion prior to sleep increased whole-body protein synthesis rates (311±8 vs 246±9 ∼mol·kg·7.5 h ) and improved net protein balance (61±5 vs -11±6 μmol·kg·7.5 h ) in the PRO vs PLA experiment, respectively; P<0.01). Mixed muscle protein synthesis rates were ∼22% higher in the PRO vs PLA experiment, which reached borderline significance (0.059±0.005 vs 0.048±0.004 %·h; P=0.05).

CONCLUSION:

This is the first study to show that protein ingested immediately prior to sleep is effectively digested and absorbed, thereby stimulating muscle protein synthesis and improving whole-body protein balance during post-exercise, overnight recovery.