Load‐sensitive adhesion factor expression in the elderly with skiing: relation to fiber type and muscle strength

Abstract

We hypothesized that 12 weeks of downhill skiing mitigates the functional deficits of knee extensor muscles in elderly subjects due to the specific recruitment of fast motor units during forceful turns on the slope. Downhill skiing led to a 1.4-fold increase in the mean cross-sectional area of slow (P=0.04)- and fast (P=0.08)-type muscle fibers. Fold changes in the expression of the structural component of focal adhesions, gamma-vinculin, were correlated with alterations in concentric force (r=0.64). Hypertrophy of fast fibers was more pronounced in women than in men (1.7 vs 1.1). Gender-specific structural-functional adjustments of knee extensor muscles and attached patellar tendon were reflected by altered expression of pro- vs de-adhesive proteins and a number of correlations. The de-adhesive protein tenascin-C was selectively increased in women compared with men (1.7 vs 1.1) while the content of the adhesive collagen XII was specifically reduced in women. The pro-adhesive focal adhesion kinase showed a specific increase in men compared with women (1.9 vs 1.1). Our findings indicate that quantitatively matched adaptations in slow and fast motor units of extensor muscle underlie the preventive effect of skiing against sarcopenia and support that hypertrophy and reinforcement of fiber adhesion operate in the improvement of muscle strength.

T/T homozygosity of the tenascin-C gene polymorphism rs2104772 negatively influences exercise-induced angiogenesis

“…The 230-kDa isoform of Tenascin-C was abundantly detected in vastus lateralis ([26]; Fig 4). Before training, a genotype effect was evident in vastus lateralis muscle for the relative content of tenascin-C protein vs. actin (Fig 4).…”

“…The bands corresponding to the tagged proteins were detected using chemoluminescence (Femto kit; Pierce, Fisher Scientific, Wohlen, Switzerland) and recorded using a Chemidoc system with Quantity One software (Bio-Rad, Hercules, CA, USA). Tenascin-C protein content was estimated for the monomer of the 230-kDa isoform [26]. Vimentin protein content was estimated combined for the small and large isoform [40].…”

Quantitative changes in focal adhesion kinase and its inhibitor, FRNK, drive load-dependent expression of costamere components

“…It is, however, not known through which mechanism load-modulated muscle atrophy and hypertrophy is associated with the regulation of costamere components in intact skeletal muscle. Specifically, it is not understood how acute posttranslational regulation of FAK on tyrosine 397, which serves as readout for integrin-associated mechanotransduction (28,32,53), relates to the reported changes in FAK content with prolonged changes in muscle loading (14,17,21) and how this may come into play in the regulation of costamere component expression. To this end, we measured the relationship between posttranslational regulation and expression of FAK in the tenotomy model of rat soleus muscle overload.…”

“…In culture, this is a rapid process, with FAK-pY397 content being threefold increased within 2 min of stretch and being decreased within the next 10 min without changes in soluble FAK protein (32). By contrast, with chronic muscle overload, the increased content of FAK-pY397 is explained by elevated FAK protein expression (16,17,21). This view is supported by an elevated content of NH 2 -terminally immunoreactive FAK, which is indicative of activated FAK, at the sarcolemma in frequently recruited muscle fiber types (12,16).…”

Single and combined influence of ACE and ACTN3 genotypes on muscle phenotypes in octogenarians

“…The rationale for studying BMD in our study lies on the fact that muscle phenotypes (as those we measured here) are positively correlated with BMD, especially in women (Shin et al 2011). Finally, though there exist between-sex differences in the muscle strength and tendon characteristics of elderly people (Flueck et al 2011), the potential confounding effect of sex was well controlled for in our analyses: indeed, (i) we did not observe an interaction effect of sex 9 ACE I/D polymorphism or sex 9 ACTN3 R577X polymorphism on the phenotypes we studied (all P [ 0.07) and thus men and women were grouped together in all ANCOVA analyses, in which we used sex as one of the covariates; and (ii) as for sarcopenia scores, we used sexadjusted logistic regression, with the scores being expressed as sex-specific percentiles.…”