Effect of alpine skiing training on tendon mechanical properties in older men and women

Strain is one of the parameters determining tendon adaptation to mechanical stimuli. The aim of this study was to test whether the patellar tendon strain induced during recreational alpine skiing would affect tendon mechanical properties in older individuals. Twenty-two older males and females (67 ± 2 years) were assigned to a 12-week guided skiing programme (IG) and 20 aged-matched volunteers served as controls (CG). Patellar tendon mechanical properties and cross-sectional area (CSA) were measured before and after training, with combined dynamometry and ultrasonography scanning. None of the variables changed significantly in the CG after training. In the IG, tendon stiffness and Young's modulus were increased (respectively, 14% and 12%, P<0.01), without any significant change in tendon CSA. In addition, changes in tendon stiffness were blunted in women (9%) compared with men (19%). Serum IGF-1 concentration tended to be lower in women (-19%, P=0.07). These results demonstrate that the mechanical stimulus induced by alpine skiing is sufficient to elicit adaptive changes in patellar tendon mechanical and material properties in older subjects. Furthermore, the present sex-specific adaptations are consistent with previous reports of lower collagen metabolic responsiveness in women and may be underpinned by anthropometric and metabolic differences.

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

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.