Signaling Responses After Varying Sequencing of Strength and Endurance Training in a Fed State.
Level 2 - randomized trial
Individual randomized trial
PubMed 26694228 · doi:10.1123/ijspp.2015-0534
What was done
Eighteen resistance-trained men were randomly assigned to one of three exercise conditions in a fed state: strength training alone (ST), strength followed by endurance training (ST-END), or endurance followed by strength training (END-ST). Vastus lateralis muscle biopsies were collected before exercise, immediately on cessation of exercise, and 1 h after cessation of strength training to measure total and phosphorylated proteins in the mTOR and AMPK signaling networks.
What was found
Strength-training performance was similar across all groups. Phosphorylated S6k1 (p-S6k1) increased from baseline at 1 h post-training in ST and ST-END (both P < .05). p-4E-BP1 was significantly lower than baseline post-ST (P = .01), whereas at 1 h post-exercise in ST-END it was significantly greater than immediately post-exercise (P = .04). p-ACC increased from baseline immediately and 1 h post-exercise in END-ST (both P < .05). Total and phosphorylated AMPK, mTOR, p38, PKB, and eEF2 responded similarly across ST, ST-END, and END-ST.
Why it matters
In a fed state, altering the sequence of strength and endurance exercise within an acute training bout does not distinctly favor or impair downstream anabolic signaling pathways.
Limits
Small sample size (18 participants divided across three groups). The study measured only acute signaling responses up to 1 hour post-exercise rather than direct muscle protein synthesis rates or chronic adaptations in strength and hypertrophy. Tested only fed, resistance-trained men.
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