This is not going to be a long in-depth blog. In fact, it will simply provide a very condensed review of the paper recently published by Churchward-Venne et al (2016) in the Sports Medicine journal where they discuss: “the current state of evidence regarding the dose-dependent relationship between dietary protein ingestion and changes in skeletal muscle protein synthesis during recovery from resistance-type exercise in older adults. They provide recommendations on the amount of protein that may be required to maximize skeletal muscle reconditioning in response to resistance-type exercise in older adults.”

With an approximately $US50 cost to access this article, most will  simply not be willing to fork out that sort of money. So I wanted to outline the key points that were made in this article and provide a little bit more than what appears in the below online abstract. If you have any questions or want further information just leave a comment at the end of the article and I’ll get back to you as soon as possible.

ABSTRACT: Hyperaminoacidemia following protein ingestion enhances the anabolic effect of resistance-type exercise by increasing the stimulation of muscle protein synthesis and attenuating the exercise-mediated increase in muscle protein breakdown rates. Although factors such as the source of protein ingested and the timing of intake relative to exercise can impact post-exercise muscle protein synthesis rates, the amount of protein ingested after exercise appears to be the key nutritional factor dictating the magnitude of the muscle protein synthetic response during post-exercise recovery. In younger adults, muscle protein synthesis rates after resistance-type exercise respond in a dose-dependent manner to ingested protein and are maximally stimulated following ingestion of ~20 g of protein. In contrast to younger adults, older adults are less sensitive to smaller doses of ingested protein (less than ~20 g) after exercise, as evidenced by an attenuated increase in muscle protein synthesis rates during post-exercise recovery. However, older muscle appears to retain the capacity to display a robust stimulation of muscle protein synthesis in response to the ingestion of greater doses of protein (~40 g), and such an amount may be required for older adults to achieve a robust stimulation of muscle protein synthesis during post-exercise recovery. The aim of this article is to discuss the current state of evidence regarding the dose-dependent relationship between dietary protein ingestion and changes in skeletal muscle protein synthesis during recovery from resistance-type exercise in older adults. We provide recommendations on the amount of protein that may be required to maximize skeletal muscle reconditioning in response to resistance-type exercise in older adults.

Key points

• The key question often posed in relation to diet and resistance training is: “How much protein should I consume after a workout/training session to maximise the adaptive response to resistance-type exercise?”
• Whilst the answer to this question is not entirely clear what is known is that this depends on 4 key things: age, bodyweight, energy balance and possibly training status.
• Evidence shows that maximising skeletal muscle protein synthesis rates during recovery from resistance training exercise in younger adults is sufficiently accommodated by the ingestion of ∼20 g of protein or ∼0.25 g protein/kilogram bodyweight.
• Older adults demonstrate a blunted post-prandial muscle protein synthetic response.
• However, older adults as opposed to younger adults require higher amounts of protein during recovery from resistance training exercise to optimally stimulate muscle protein syntheis. Intakes even up to ∼40 g appear necessary.
• No consensus currently exists regarding the amount of protein required to maximally stimulate skeletal muscle protein synethsis rates during recovery from resistance training exercise in older adults.

• Given that older adults not involved in resistance training or vigourous physical activity require an increased intake of protein relative to younger adults, a higher protein intake seems warranted post-exercise after performing resistance training.
• Leucine-enriched whey protein or increased EAA providing 3.5 g leucine have prolonged the duration of the increase in myofibrillar protein synthesis rates following resistive exercise in older men.
• Technically, the capacity of older skeletal muscle to robustly respond with increased protein synthetic response post-resistive exercise may relate to leucine-mediated increases in p70S6K1 (Thr389) phosphorylation and/or amino acid transporter expression.
• The availability of dietary protein-derived amino acids within the circulation following protein ingestion is reduced in older adults.
• The ‘optimal’ dose of ingested protein as previously mentioned may therefore be double (∼40 g) that required by younger adults.
• The dose of ingested protein to induce a maximal stimulation of muscle protein synethesis following resistive exercise appears to increase during energy deficit versus energy balance.
• Greater rates of muscle protein synethesis have been demonstrated when 30 g versus 15 g of whey protein were consumed after training in younger adults when under conditions of mild energy deficit.
• Older adults in energy deficit and engaged in resistive exercise may require even higher amounts of post-exercise protein >40 g but <50 g; however, this is based entirely from extrapolating from younger adults and is therefore speculative at this point in time
• There is a lack of data as to the amount of ingested protein required to maximally stimulate skeletal muscle protein synthesis after resistance-type exercise in younger and older women.
• Continued research is required to unravel the contribution of ageing versus age-related decreases in physical activity on anabolic resistance and whether or not resistive exercise and/or increases in physical activity can reduce age-related anabolic resistance to protein feeding.
• Work on masters athletes with above-average fitness and muscular strength will hopefully help researchers decipher the exact nature of anabolic age-related resistance.
• It is envisaged that this will provide valuable guidance on how best to attenuate these changes through resistive exercise and/or physical activity in addition to nutritional strategies aimed at facilitating maximal muscle protein synthesis.

Reference

Churchward-Venne TA. et al. (2016) “What is the Optimal Amount of Protein to Support Post-Exercise Skeletal Muscle Reconditioning in the Older Adult?” Sports Medicine (see here for publication)

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