IGF-I stimulates hypertrophy and differentiation of cardiomyocytes, as demonstrated in in vivo and in vitro studies (21, 22).
On the other hand, ERK is also critically related to IGF-I-induced hypertrophy in rat plantaris (Haddad and Adams 2004), which is predominantly composed of type II fibers (type IIA: ~40%, type IIB: ~40%; (Armstrong and Phelps 1984).
Likewise, GH was associated with changes in type I fibre hypertrophy and yet is reported to have no effect on myofibrillar protein accretion (Meinhardt et al. 2010; Rennie 2003; Yarasheski et al. 1993).
Conversely, resistance exercise induces morphological and neurological adaptations which contribute to changes in muscle neural firing pattern, size (i.e., hypertrophy), and function (i.e., strength and power) [10, 11].
Chondrogenic induction with TGF- β is often associated with the hypertrophy (i.e., upregulation of collagen X) [ 41].
Experimental animal studies have demonstrated that the bladder progresses through three sequential stages (i.e., hypertrophy, compensation, and decompensation) in partial BOO [ 7].
It has also been shown that rapamycin can prevent chronic mechanical-overload-induced increases in fiber size (i.e. hypertrophy) (Bodine et al., 2001; Goodman et al., 2011a).
In contrast, adult mammalian CMs have long been thought to be terminally differentiated and thus post-mitotic [ 16– 18] and much of the growth of the postnatal mammalian heart occurs via enlargement of pre-existing CMs, i.e., hypertrophy [ 18, 19].
Further histochemical analysis (data not included) showed that the increased ST weights were associated with increased muscle fibre diameters (i.e. hypertrophy), with the fast fibres being mainly affected.
Although there are numerous studies that reported changes in muscle metabolism, none provide compelling evidence that EST, similar to the paradigms used in clinical settings, produces early muscle hypertrophy (i.e., in less than 6 weeks).
