Exercise Plus Presleep Protein Ingestion Increases Overnight Muscle Connective Tissue Protein Synthesis Rates in Healthy Older Men

Abstract

Protein ingestion and exercise stimulate myofibrillar protein synthesis rates. When combined, exercise further increases the postprandial rise in myofibrillar protein synthesis rates. It remains unclear whether protein ingestion with or without exercise also stimulates muscle connective tissue protein synthesis rates. The authors assessed the impact of presleep protein ingestion on overnight muscle connective tissue protein synthesis rates at rest and during recovery from resistance-type exercise in older men. Thirty-six healthy, older men were randomly assigned to ingest 40 g intrinsically L-[1-13C]-phenylalanine and L-[1-13C]-leucine-labeled casein protein (PRO, n = 12) or a nonprotein placebo (PLA, n = 12) before going to sleep. A third group performed a single bout of resistance-type exercise in the evening before ingesting 40 g intrinsically-labeled casein protein prior to sleep (EX+PRO, n = 12). Continuous intravenous infusions of L-[ring-2H5]-phenylalanine and L-[1-13C]-leucine were applied with blood and muscle tissue samples collected throughout overnight sleep. Presleep protein ingestion did not increase muscle connective tissue protein synthesis rates (0.049 ± 0.013 vs. 0.060 ± 0.024%/hr in PLA and PRO, respectively; p = .73). Exercise plus protein ingestion resulted in greater overnight muscle connective tissue protein synthesis rates (0.095 ± 0.022%/hr) when compared with PLA and PRO (p < .01). Exercise increased the incorporation of dietary protein-derived amino acids into muscle connective tissue protein (0.036 ± 0.013 vs. 0.054 ± 0.009 mole percent excess in PRO vs. EX+PRO, respectively; p < .01). In conclusion, resistance-type exercise plus presleep protein ingestion increases overnight muscle connective tissue protein synthesis rates in older men. Exercise enhances the utilization of dietary protein-derived amino acids as precursors for de novo muscle connective tissue protein synthesis during overnight sleep.

The impact of collagen protein ingestion on musculoskeletal connective tissue remodeling: a narrative review

“…For instance, it has been speculated that protein sources delivering large amounts of the key amino acids used for connective tissue protein synthesis (ie, glycine and proline) may be more suitable for facilitating increased connective tissue protein synthesis rates. 13 , 14 , 89 , 90 This hypothesis is discussed in the following sections.…”

“…Both endurance- 71 , 72 and resistance-type exercise 13 , 14 , 25 , 27 , 28 , 73 increase muscle connective tissue protein synthesis in humans. Lengthening contractions more robustly increase postexercise intramuscular connective tissue protein synthesis rates than do shortening contractions, reflecting the potent stimulatory effect of increased tension within contracting muscle tissue.…”

“…Recently, we demonstrated that the ingestion of a larger, 40-g dose of casein protein does not result in increase in intramuscular collagen protein synthesis rates over a more prolonged postprandial period during overnight sleep (7.5 h). 13 …”

“…Follow-up work demonstrated that the utilization of the ingested protein-derived amino acids for de novo intramuscular connective tissue protein synthesis is further enhanced during recovery from resistance exercise. 13 Together, the observations that dietary protein–derived amino acids are incorporated into connective tissue protein and modulated with physical activity implies that dietary provision of amino acids is required and that there may be conditions where intramuscular connective tissue remodeling can be facilitated or compromised. For instance, it has been speculated that protein sources delivering large amounts of the key amino acids used for connective tissue protein synthesis (ie, glycine and proline) may be more suitable for facilitating increased connective tissue protein synthesis rates.…”

“…Physical activity potently increases connective tissue synthesis rates, leading to enhanced remodeling and more effective transfer of contractile force. 13–16 On the other hand, physical inactivity reduces connective tissue synthesis rates. 17 , 18 Impairments in connective tissue remodeling may lead to structural changes in tissues that compromise their mechanical properties and contribute to the development of musculoskeletal injury.…”