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Trop peu de repos entre les séries réduit-il la riposte anabolique?

03/10/2015 | Etudes Musculation

 

Short inter-set rest duration impairs resistance exercise-induced
rates of myofibrillar protein synthesis in young males

James McKendry         Appl. Physiol. Nutr. Metab. Vol. 40, 2015 pS41

Resistance exercise contractile variables can be manipulated to enhance
the muscle morphological response. Reducing the duration of
rest-recovery taken between sets of resistance exercise (≤1 min) influences
systemic concentrations of hormones thought to be critical for
muscle hypertrophy. However, local mechanisms activated through
the mechanical stress resistance exercise places on the muscle may act
as intrinsic ‘drivers’ of hypertrophy, irrespective of the endocrine
response.

The aim of this study was to determine the acute muscle
anabolic response to a bout of resistance exercise performed with
contrasting inter-set rest durations. In a parallel designed study,
16 males completed 4 sets of bilateral leg press (LP) and knee extension
(KE) exercise at 75% of 1RM to momentary failure followed by ingestion
of 25g of whey protein.

Resistance exercise sets were interspersed by 1 min (1 M; n=8) or 5 min (5 M; n=8). Muscle biopsies of the vastus
lateralis were obtained at rest, 0, 4, 24 and 28 h postexercise during a
primed-continuous infusion of L-[ring-13C6] phenylalanine to determine
rates of myofibrillar protein synthesis (MPS) and anabolic signalling
in the ‘early’ (0-4 h) and ‘late’ (24-28 h) recovery phase. 1M induced
a greater elevation in plasma lactate and serum testosterone compared
with 5 M, with no difference between groups in serum growth
hormone response.

Total work volume (reps x sets x load) was 13%
lower for LP (P = 0.01) and 17% lower for KE (P = 0.029) in 1 M compared
with 5 M.

Rates of MPS increased above basal values by 80 and 150%
over 0-4 h post-exercise for 1 M and 5 M, respectively.
The rate of MPS
over 0-4 h post-exercise was significantly lower in 1 M compared with
5 M (0.040 ± 0.004 vs. 0.069 ± 0.007 %·h-1, respectively, P = 0.005). Rates
of MPS at 24-28 h post-exercise remained elevated above basal fasted
values for 1 M and 5 M (0.046 ± 0.007 and 0.046 ± 0.009 %·h-1, respectively,

P < 0.05) with no difference between groups. Immediately postexercise,
eEF2Thr56 phosphorylation was lower in 5Mcompared with
1 M (P <0.05).

In conclusion, short inter-set rest duration of 1 M impaired
resistance exerciseinduced myofibrillar protein synthesis compared
with rest-interval duration of 5 M
. We speculate that the
suppression in MPS in 1 M is notdue tothe reduction in total work, but
rather the intracellular metabolic ‘stress’ response (i.e. energy depletion),
which may have down-regulated protein translation through a
compromised anabolic signalling.

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