A thread on concurrent training. When does aerobic training start to detract from muscular/strength gains?

The primary driver of protein synthesis is the mTOR pathway and the primary driver of aerobic adaptations is AMPK pathway.

These two can get into a “tug of war”..

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over which adaptations are promoted because AMPK activity likely (but not certainly), reduces protein synthesis (Dreyer et. al, 2006).

mTOR relies on muscle glycogen to work well, while aerobic training diminishes available glycogen stores.

Studies have shown that..

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combined strength & endurance training over 10 weeks led to less strength increases vs just strength training alone (Baar, 2006; Hickson 1980).

BUT, the strength gain could very well have come from the hypertrophy gains caused via mTOR protein synthesis.

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Interestingly enough, combining both aerobic training and resistance training can be beneficial for weight-class sports because, in theory, you could still train for strength via low reps/high intensity and also performance glycogen-depleting aerobic exercise before..

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or shortly after strength training to activate AMPK and lessen the growth response associated with mTOR and still retain the neuromuscular adaptations (a primary driver in strength).

This is ultimately good information for intermediate and advanced athletes.

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I would not be overly concerned with this in beginners.

Everything works for a pure beginner, and a lot of things work for an early novice trainee or athlete. We probably don’t have to worry about this too much with them.

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