PURPOSE: Resistance training (RT) is one of the most important stimuli for muscle hypertrophy, but it may play also an important role on weight loss and fatty acid (FA) oxidation increase. It has been largely demonstrated that RT affects anabolic pathways but, considering the numerous variables of RT, the differences between various training techniques has been till now poorly investigated. The aim of this study was to assess Akt, ERK, 4EBP1, S6 and AMPK, ACC signalling after a single bout of high-intensity interval resistance training (HIIRT) and of traditional resistance training (TRT).
METHODS: 12 healthy subjects performed in two different moments and with different legs HIIRT and TRT protocol. HIIRT consisted in 2 sets of 6/2/2 reps with incomplete rest between (20”) sets while TRT consisted of 4 sets x15 reps with 1’15” of rest between sets. Biopsies from the vastus lateralis were taken one week before training sessions (pre), immediately after (T0), 6 hours after (T6) and 24 hours after (T24) training. Western blot and RT-PCR mRNA analysis were performed, results were described as arbitrary unit.
RESULTS: No significant differences were found at any of time points in AKT, ERK and 4EBP1 phosphorylation. There was a significant increase in S6-P phosphorylation at T6 both in HIIRT (p<0.005) and TRT (p<0.001). TRT showed a significant increased at T24 of AMPK-P compared to HIIRT (p<0.05). ACC-P showed a similar although not significant increase at T0 in both training. mRNA analysis showed that HIIRT seems to be more related to mechanical deformation (MGF), while the TRT seems to act on IGF-1 pathway.
CONCLUSIONS: Our findings suggest that a less time commitment resistance training technique is, at least, equally effective to induce an increase of S6-P whilst TRT seems to be more effective to stimulated oxidative pathway. This data seems confirm that the manipulation of different variables of RT induces different molecular and metabolic responses related to the activation of specific muscle signalling pathways.