Signalling responses after varying sequencing of strength and endurance training in a fed state

Purpose: The objective of this study was to compare anabolic signalling responses to differing sequences of concurrent strength and endurance training in a fed state. Methods: Eighteen resistance-trained males were randomly assigned to the following experimental conditions; i) strength training (ST), ii) strength followed by endurance training (ST-END) or iii) endurance followed by strength training (END-ST). Muscle tissue samples were taken from the vastus lateralis before each exercise protocol, upon cessation of exercise, and 1 h-post cessation of strength training. Tissue was analysed for total and phosphorylated (p-) signalling proteins linked to the mTOR and AMPK networks. Results: Strength training performance was similar between ST, ST-END and END-ST. p-S6k1 was elevated from baseline 1 h post training in ST and ST-END (both p < 0.05). p-4E-BP1 was significantly lower than baseline post ST (p = 0.01), while 1 h post exercise in the ST-END condition p-4E-BP1 was significantly greater than post exercise (p = 0.04). p-ACC was elevated from baseline both post and 1 h post exercise (both p < 0.05) in the END-ST condition. AMPK, mTOR, p38, PKB, eEF2 responded similarly to the ST, ST-END and END-ST. Signalling responses to ST, ST-END and END were largely similar. As such it cannot be ascertained which sequence of concurrent strength and endurance training is most favourable in promoting anabolic signalling. Conclusions: These data indicate that in the case of the present study an acute bout of concurrent training of differing sequences elicited similar responses of the AMPK and mTOR networks. Key words: Combined exercise, mTOR, AMPK, exercise order, anabolic signalling