I have not had time yet to review this entire study, and I suspect given it's age it has been reference in the nut forums already, but I wanted to see if anyone could clarify
some things I saw in the abstract:
https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3381813/
"Muscle protein synthesis (MPS) is the driving force behind adaptive responses to exercise and represents a widely adopted proxy for gauging chronic efficacy of acute interventions, (i.e. exercise/nutrition). Recent findings in this arena have been progressive. Nutrient-driven increases in MPS are of finite duration (∼1.5 h), switching off thereafter despite sustained amino acid availability and intramuscular anabolic signalling. Intriguingly, this ‘muscle-full set-point’ is delayed by resistance exercise (RE) (i.e. the feeding × exercise combination is ‘more anabolic’ than nutrition alone) even ≥24 h beyond a single exercise bout, casting doubt on the importance of nutrient timing vs. sufficiency per se. Studies manipulating exercise intensity/workload have shown that increases in MPS are negligible with RE at 20–40% but maximal at 70–90% of one-repetition maximum when workload is matched (according to load × repetition number). However, low-intensity exercise performed to failure equalises this response. Analysing distinct subcellular fractions (e.g. myofibrillar, sarcoplasmic, mitochondrial) may provide a readout of chronic exercise efficacy in addition to effect size in MPS per se, i.e. while ‘mixed’ MPS increases similarly with endurance and RE, increases in myofibrillar MPS are specific to RE, prophetic of adaptation (i.e. hypertrophy). Finally, the molecular regulation of MPS by exercise and its regulation via ‘anabolic’ hormones (e.g. IGF-1) has been questioned, leading to discovery of alternative mechanosensing–signalling to MPS."
1. "Nutrient-driven increases in MPS are of finite duration (∼1.5 h)..."
Does this statement mean that, in the absence of recent (>24hour after) training to stimulate MPS, nutrient-driven rises in MPS only last for ~1.5hr? If so, then what exactly is the function of stimulating MPS via nutrition if there is no recent training to which the rise in MPS can aid in hypertrophy or adaptation?
In other words, if the window after training wherein your body is still recovery from/adapting to stimulus has ended (say, >24 hours), then what exactly does a nutrient-driven rise in MPS actually do considering you've already adapted? Do your muscles grow from nutrient-driven MPS even if you're not training?
Finally, does this in any way suggest that consuming protein - for example - every couple of hours when you're NOT actively training (say a person goes on vacation or takes a week-long break) would better to maintain MPS uptime?
2. "Intriguingly, this ‘muscle-full set-point’ is delayed by resistance exercise (RE) (i.e. the feeding × exercise combination is ‘more anabolic’ than nutrition alone) even ≥24 h beyond a single exercise bout, casting doubt on the importance of nutrient timing vs. sufficiency per se"
Here, the author states that the 'feeding x exercise combination is 'more anabolic' than nutrition alone', thus mitigating the impacts of nutrient timing vs sufficiency. It seems to me that, if that is true, then the impact of consuming food after training and/or before training would actually be somewhat important if the anabolic effect is increased by having both in combination and in close proximity. Not to say you need a protein shake RIGHT after training, but if the increase is driven by training + food, it seems like it would make sense to get it in ASAP...
3. "However, low-intensity exercise performed to failure equalises this response."
Finally, this appears to suggest that low-intensity training done to failure actually stimulates MPS sufficiently to optimize conditions. If that is true, then could a person not do, say, several sets of push-ups to failure on 'off' days simply to maintain maximal MPS uptime? Also, is this something a person could take advantage of during period wherein injury, insufficient time, etc kept them out of the gym wherein they could perform training with heavier loads?
Thanks for any help.
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