Age-related slowing of maximum running speed was characterized by a decline in stride length and an increase in contact time along with a lower magnitude of GRFs. The sprint-trained athletes demonstrated an age-related selective muscular atrophy and reduced force capacity that contributed to the deterioration in sprint running ability with age.

Muscle strength and mass decline in sedentary individuals with aging. The present study investigated the effects of both age and 21 weeks of progressive hypertrophic resistance training (RT) on skeletal muscle size and strength, and on myostatin and myogenin mRNA expression in 21 previously untrained young men (26.0 ± 4.3 years) and 18 older men (61.2 ± 4.1 years) and age-matched controls. Vastus lateralis muscle biopsies were taken before and after RT. Type I and type II muscle fiber cross-sectional areas increased more in young men than in older men after RT (P < 0.05). Concentric leg extension increased (P < 0.05) more after 10.5 weeks in young men compared to older men, but after 21 weeks no statistical differences existed. The daily energy and protein intake were greater (P < 0.001) in young subjects. Both myostatin and myogenin mRNA expression increased in older when compared with young men after RT (P < 0.05). In conclusion, after RT, muscle fiber size increased less in older compared to young men. This was associated with lower protein and energy intake and increases in myostatin gene expression in older when compared to young men.

Differences in body composition and performance were investigated between elite and U20 male ice hockey players of two different national standards. 179 players were recruited from the highest Finnish (n=82) and Danish (n=61) national level. In addition, one U20 team from Finland (n=19) and Denmark (n=17) participated. Body composition and countermovement jump performance (CMJ) were measured off-ice in addition to on-ice assessments of agility, 10 and 30-m sprint performance and endurance capacity (the maximal Yo-Yo Intermittent Recovery Level 1 Ice Hockey Test, Yo-Yo IR1-IHmax). Large differences in on-ice performances were demonstrated between Finnish and Danish elite players for agility, 10 and 30-m sprint performance (2-3%, P≤0.05) and Yo-Yo-IR1-IHmax performance (15%, P≤0.05).In contrast, no differences (P>0.05) were present between elite players for CMJ ability or body composition. However, elite players possessed more body and muscle mass than U20 players.Finally, the Finnish U20 cohort had a similar performance level as the Danish elite players and superior 10-m sprint performance, whereas the Danish U20 level was inferior to the other groups in every performance assessment (P≤0.05). In conclusion, on-ice speed and endurance differ markedly between elite players of two national standards with no difference in body composition or CMJ ability. Moreover, the most consistent difference between U20 and senior elite players was related to body and muscle mass. These results highlight the usefulness of on-ice assessments and suggests the importance of on-ice high-intensity training in elite players in addition to training targeted the development of lean body mass in youth prospects.

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