Protein considerations for optimising skeletal muscle

Skeletal muscle is critical for human health. Protein feeding, alongside resistance exercise, 12 is a potent stimulus for muscle protein synthesis (MPS) and is a key factor that regulates skeletal 13 muscle mass (SMM). The main purpose of this narrative review was to evaluate the latest evidence 14 for optimising the amino acid or protein source, dose, timing, pattern and macronutrient coingestion 15 for increasing or preserving SMM in healthy young and healthy older adults. We used a systematic 16 search strategy of PubMed and Web of Science to retrieve all articles related to this review objective. 17 In summary, our findings support the notion that protein guidelines for increasing or preserving 18 SMM are more complex than simply recommending a total daily amount of protein. Instead, 19 multifactorial interactions between protein source, dose, timing, pattern and macronutrient 20 coingestion, alongside exercise, influence the stimulation of MPS, and thus should be considered in 21 the context of protein recommendations for regulating SMM. To conclude, on the basis of currently 22 available scientific literature, protein recommendations for optimising SMM should be tailored to 23 the population or context of interest, with consideration given to age and resting/post resistance 24 exercise conditions. 25