Animal models for inducing muscle hypertrophy: are they relevant for clinical applications in humans?

Muscle hypertrophy is an adaptive response to overload. Progressive resistance exercise (PRE) is thought to be among the best means to achieve hypertrophy in humans. While functional adaptations to PRE in muscles of humans are made in the clinic, it is difficult to evaluate hypertrophic responses and underlying mechanisms because the adaptations require many weeks or months before they become evident and there is a large variability in response to PRE among humans. In contrast, various animal models have been shown to induce rapid and extensive muscle hypertrophy and some models allow precise control of the exercise parameters. By examining the animal models of muscle hypertrophy and understanding the advantages and disadvantages of each, clinicians may be able to evaluate and use relevant data from these models to design new strategies for modification of PRE in humans. The purpose of this article is to review animal models that are currently used in basic research laboratories, discuss the hypertrophic and functional outcomes, and relate these to PRE used in the clinic.