The distribution of eukaryotic initiation factor 4E after bouts of resistance exercise is altered by shortening of recov
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The Journal of Physiological Sciences Open Access
ORIGINAL PAPER
The distribution of eukaryotic initiation factor 4E after bouts of resistance exercise is altered by shortening of recovery periods Junya Takegaki1,2* , Riki Ogasawara3 , Karina Kouzaki4, Satoshi Fujita5, Koichi Nakazato4 and Naokata Ishii1
Abstract Insufficient duration of recovery between resistance exercise bouts reduces the effects of exercise training, but the influence on muscle anabolic responses is not fully understood. Here, we investigated the changes in the distribution of eukaryotic initiation factor (eIF) 4E, a key regulator of translation initiation, and related factors in mouse skeletal muscle after three successive bouts of resistance exercise with three durations of recovery periods (72 h: conventional, 24 h: shorter, and 8 h: excessively shorter). Bouts of resistance exercise dissociated eIF4E from eIF4E binding protein 1, with the magnitude increasing with shorter recovery. Whereas bouts of resistance exercise with 72 h recovery increased the association of eIF4E and eIF4G, those with shorter recovery did not. Similar results were observed in muscle protein synthesis. These results suggest that insufficient recovery inhibited the association of eIF4E and eIF4G, which might cause attenuation of protein synthesis activation after bouts of resistance exercise. Keywords: Resistance exercise, Recovery, Skeletal muscle, Protein synthesis, Translation initiation complex Background Skeletal muscle mass is regulated by muscle protein metabolism, and the accumulation of protein synthesis causes muscle hypertrophy. Resistance exercise is well known to transiently activate protein synthesis, and resistance exercise training promotes muscle growth. The recovery period is one of the determinants of the training effect, and a period of 2 or 3 days is regarded as adequate for inducing muscle hypertrophy [1]. Resistance exercise training with an excessively short recovery period can lead to inadequate responses, such as suppression of protein synthesis and activation of muscle protein degradation systems [2–4]. However, little information is available on the mechanisms underlying the suppression of acute and chronic responses of muscle anabolism after
*Correspondence: [email protected] 2 Ritsumeikan Global Innovation Research Organization, Ritsumeikan University, 1‑1‑1 Noji‑higashi, Kusatsu, Shiga 525‑8577, Japan Full list of author information is available at the end of the article
bouts of resistance exercise training with insufficient recovery. Although the detailed mechanisms for the activation of muscle protein synthesis and muscle hypertrophy in resistance exercise training are not fully understood, mechanistic target of rapamycin complex (mTORC) plays a role in this process [5–7]. A recent study reported that mTORC1 plays a minor role in the acute activation of muscle protein synthesis but is essential for muscle hypertrophy induced by chronic mechanical overload [8]. Additionally, repetitive resistance exercise with excessive
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