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Volitional Weight-Lifting in Rats Promotes Adaptation via Performance and Muscle Morphology prior to Gains in Muscle Mass.

Rader EP, Miller GR, Chetlin RD, Wirth O, Baker BA - Environ Health Insights (2014)

Bottom Line: Exclusively following 700 g load training, forces increased by 21% whereas muscle masses remained unaltered.For soleus (SOL) and tibialis anterior (TA) muscles, 700 g load training increased muscle fiber number per unit area by ∼20% and decreased muscle fiber area by ∼20%.Additionally, number of muscle fibers per section increased by 18% for SOL muscles.

View Article: PubMed Central - PubMed

Affiliation: Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA.

ABSTRACT
Investigation of volitional animal models of resistance training has been instrumental in our understanding of adaptive training. However, these studies have lacked reactive force measurements, a precise performance measure, and morphological analysis at a distinct phase of training - when initial strength gains precede muscle hypertrophy. Our aim was to expose rats to one month of training (70 or 700 g load) on a custom-designed weight-lifting apparatus for analysis of reactive forces and muscle morphology prior to muscle hypertrophy. Exclusively following 700 g load training, forces increased by 21% whereas muscle masses remained unaltered. For soleus (SOL) and tibialis anterior (TA) muscles, 700 g load training increased muscle fiber number per unit area by ∼20% and decreased muscle fiber area by ∼20%. Additionally, number of muscle fibers per section increased by 18% for SOL muscles. These results establish that distinct morphological alterations accompany early strength gains in a volitional animal model of load-dependent adaptive resistance training.

No MeSH data available.


Related in: MedlinePlus

No indications of chronic degeneration/regeneration or alterations to the interstitium with training. Transverse sections of SOL muscles stained with hematoxylin and eosin. Scale bar = 50 μm.
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f3-ehi-suppl.1-2014-001: No indications of chronic degeneration/regeneration or alterations to the interstitium with training. Transverse sections of SOL muscles stained with hematoxylin and eosin. Scale bar = 50 μm.

Mentions: The performance gain was not accompanied by increased muscle mass, thereby excluding muscle mass as a factor for the adaptation (Table 1, Figure 2). To investigate muscle morphology, muscle transverse sections were evaluated. No training effect was observed in the percentage of muscle tissue composed of non-degenerative muscle fibers, degenerative muscle fibers, or centrally nucleated fibers (Table 2, Figure 3, Supplementary Figure 1A–C). This was also consistent with the absence of changes in the cellular and non-cellular interstitium, indicating a lack of edema and the absence of accumulated connective tissue (Table 2, Figure 3, Supplementary Figure 1A–C). Overall, these results indicate that chronic cycles of degeneration/regeneration did not accompany training.


Volitional Weight-Lifting in Rats Promotes Adaptation via Performance and Muscle Morphology prior to Gains in Muscle Mass.

Rader EP, Miller GR, Chetlin RD, Wirth O, Baker BA - Environ Health Insights (2014)

No indications of chronic degeneration/regeneration or alterations to the interstitium with training. Transverse sections of SOL muscles stained with hematoxylin and eosin. Scale bar = 50 μm.
© Copyright Policy - open-access
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC4216651&req=5

f3-ehi-suppl.1-2014-001: No indications of chronic degeneration/regeneration or alterations to the interstitium with training. Transverse sections of SOL muscles stained with hematoxylin and eosin. Scale bar = 50 μm.
Mentions: The performance gain was not accompanied by increased muscle mass, thereby excluding muscle mass as a factor for the adaptation (Table 1, Figure 2). To investigate muscle morphology, muscle transverse sections were evaluated. No training effect was observed in the percentage of muscle tissue composed of non-degenerative muscle fibers, degenerative muscle fibers, or centrally nucleated fibers (Table 2, Figure 3, Supplementary Figure 1A–C). This was also consistent with the absence of changes in the cellular and non-cellular interstitium, indicating a lack of edema and the absence of accumulated connective tissue (Table 2, Figure 3, Supplementary Figure 1A–C). Overall, these results indicate that chronic cycles of degeneration/regeneration did not accompany training.

Bottom Line: Exclusively following 700 g load training, forces increased by 21% whereas muscle masses remained unaltered.For soleus (SOL) and tibialis anterior (TA) muscles, 700 g load training increased muscle fiber number per unit area by ∼20% and decreased muscle fiber area by ∼20%.Additionally, number of muscle fibers per section increased by 18% for SOL muscles.

View Article: PubMed Central - PubMed

Affiliation: Centers for Disease Control and Prevention, National Institute for Occupational Safety and Health, Morgantown, WV, USA.

ABSTRACT
Investigation of volitional animal models of resistance training has been instrumental in our understanding of adaptive training. However, these studies have lacked reactive force measurements, a precise performance measure, and morphological analysis at a distinct phase of training - when initial strength gains precede muscle hypertrophy. Our aim was to expose rats to one month of training (70 or 700 g load) on a custom-designed weight-lifting apparatus for analysis of reactive forces and muscle morphology prior to muscle hypertrophy. Exclusively following 700 g load training, forces increased by 21% whereas muscle masses remained unaltered. For soleus (SOL) and tibialis anterior (TA) muscles, 700 g load training increased muscle fiber number per unit area by ∼20% and decreased muscle fiber area by ∼20%. Additionally, number of muscle fibers per section increased by 18% for SOL muscles. These results establish that distinct morphological alterations accompany early strength gains in a volitional animal model of load-dependent adaptive resistance training.

No MeSH data available.


Related in: MedlinePlus