High‐Intensity Resistance Training with Insufficient Recovery Time Between Bouts Induce Atrophy and Alterations in Myosin Heavy Chain Content in Rat Skeletal Muscle

Abstract

The aim of this study was to test whether high-intensity resistance training with insufficient recovery time between bouts, could result in a decrease of muscle fiber cross-sectional area (CSA), alter fiber-type frequencies and myosin heavy chain (MHC) isoform content in rat skeletal muscle. Wistar rats were divided into two groups: trained (Tr) and control (Co). Tr group were subjected to a high-intensity resistance training program (5 days/week) for 12 weeks, involving jump bouts into water, carrying progressive overloads based on percentage body weight. At the end of experiment, animals were sacrificed, superficial white (SW) and deep red (DR) portions of the plantaris muscle were removed and submitted to mATPase histochemical reaction and SDS-PAGE analysis. Throughout the experiment, both groups increased body weight, but Tr was lower than Co. There was a significant reduction in IIA and IID muscle fiber CSA in the DR portion of Tr compared to Co. Muscle fiber-type frequencies showed a reduction in Types I and IIA in the DR portion and IID in the SW portion of Tr compared to Co; there was an increase in Types IIBD frequency in the DR portion. Change in muscle fiber-type frequency was supported by a significant decrease in MHCI and MHCIIa isoforms accompanied by a significant increase in MHCIIb isoform content. MHCIId showed no significant differences between groups. These data show that high-intensity resistance training with insufficient recovery time between bouts promoted muscle atrophy and a transition from slow-to-fast contractile activity in rat plantaris muscle. Anat Rec, 294:1393Rec, 294: -1400Rec, 294: , 2011. V V C 2011 Wiley-Liss, Inc.

The effects of resistance exercise on cocaine self-administration, muscle hypertrophy, and BDNF expression in the nucleus accumbens

“…In most existing models of resistance exercise, dynamic movements of the hindlimbs are motivated by electric shock, such that the subject must repeatedly jump to escape or avoid the shock (Fluckey et al, 1995; Hernandez et al, 2000; Nilsson et al, 2010; Tamaki et al, 1992). In other models, subjects are placed in a weighted vest and submerged in water, requiring the animal to jump repeatedly to the surface in order to breathe (Cunha et al, 2005; De Souza et al, 2011; Haraguchi et al, 2011). The use of these methods limits the appeal of these models because repeated exposure to pain (e.g., electric shock) and stress (e.g., water submersion) can confound behavioral and neurobiological measures relevant to substance use.…”

Animal models of resistance exercise and their application to neuroscience research

“…For example, a submersion procedure in which the subject is placed at the bottom of a shallow pool with a weighted harness is a common water-based resistance model (e.g., Cunha et al, 2005; de Souza et al, 2011; Haraguchi et al, 2011). In this model, the subject is submerged in water with progressively increasing loads attached to a weighted vest and must jump in order to escape the water.…”

Resistance Training With Excessive Training Load and Insufficient Recovery Alters Skeletal Muscle Mass–Related Protein Expression

“…For this purpose, we used a 12-week resistance training program ( Figure 1), according to a protocol previously used in our laboratory, to induce muscle overwork and consequent atrophy in plantaris muscle fast-twitch fibers (e.g., type IIA and IID fibers) (9). The intensity and volume of training were progressive throughout the experiment (Table 1), achieving an overload 15% greater than what is recommended to promote beneficial adaptations in rat skeletal muscle (e.g., muscle fiber hypertrophy) (2).…”

“…Our laboratory recently reported that a resistance training program with insufficient recovery time between bouts can induce atrophy and phenotypic alterations in rat skeletal muscle fibers (9), which indicates an increase in the protein catabolism/anabolism ratio. In this regard, Petibois et al (31) observed that overtrained individuals presented higher amino acid levels and lower blood protein accumulation in response to exercise compared with appropriately trained individuals, which suggested that proteins were catabolized for amino acid supply during exercise.…”