Muscle Fibre Typology as a Novel Risk Factor for Hamstring Strain Injuries in Professional Football (Soccer): A Prospective Cohort Study.

BACKGROUND: Hamstring strain injuries (HSI) are prevalent in team sports and occur frequently in the later phase of matches. In the search for interindividual factors that determine muscle fatigue and possibly injury risk, muscle fibre typology is a likely candidate. OBJECTIVE: The aim of the study was to determine whether muscle fibre typology is a risk factor for HSI. METHODS: A prospective cohort study was conducted over three seasons in professional football players competing in the Belgian Jupiler Pro League (n = 118) and in the English Premier League (n = 47). A total of 27 HSI were sustained during this period. Muscle fibre typology was non-invasively estimated using proton magnetic resonance spectroscopy and was characterized as a fast, slow, or intermediate typology based on the carnosine concentration in the soleus. A multivariate Cox model was used to identify risk factors for HSI. RESULTS: Football players exhibited a wide variety of muscle typologies (slow 44.9%, intermediate 39.8%, fast 15.3%). In the combined cohort, players with a fast typology displayed a 5.3-fold (95% confidence interval [CI] 1.92-14.8; P = 0.001) higher risk of sustaining an index HSI than slow typology players. This was also independently observed in both leagues separately as, respectively, a 6.7-fold (95% CI 1.3-34.1; P = 0.023) and a 5.1-fold (95% CI 1.2-20.4; P = 0.023) higher chance was found in fast typology players than in slow typology players of the Jupiler Pro League and the Premier League cohort. CONCLUSION: We identified muscle fibre typology as a novel and potent risk factor for HSI in team sports.

The contribution of growth and maturation in the functional capacity and skill performance of male adolescent handball players.

The present study determined to what extent the variance in performance might be explained by chronological age, biological maturation, training load and anthropometry in 168 Belgian male handball players aged 14 years: anthropometric, strength, speed and sport-specific skills were assessed. MANOVA tested the effect of chronological age and biological maturity, whereas MANCOVA was used to compare maturity groups controlling for chronological age and training load. In addition, canonical correlation analysis was used between age, maturity-offset and anthropometry, on one side, and performance and sport-specific skills, on the other side. Results revealed significant differences between early, on-time and late maturity groups for anthropometry (p<0.001), strength (p<0.001) and sprint 20-m (p<0.05) in favour of the early maturing players. The difference between the mean values of the extreme groups for height was 24.8 cm, for weight 33.2 kg and, for body fat 6.5%; for handgrip 20.2 kg, for 5-jump test 1.1 m and for 20-m sprint 0.20 s. Maturity status had no effect on sport-specific skills. Canonical correlations indicated that poorer scores in sport-specific skills were related to fatness and lack of training. In parallel, a substantial relationship was found between early maturity-offset, body size, strength and 20-m sprint.

The KörperkoordinationsTest für Kinder: reference values and suitability for 6-12-year-old children in Flanders.

An adequate coordination level in children is important for their general development, but also for health, psychosocial, academic and well-being-related reasons. In this study, the suitability of the KörperkoordinationsTest für Kinder (KTK) as an assessment instrument for the gross motor coordination was evaluated in 2470 children from 26 elementary schools for general education spread over the Flemish and Brussels-capital region. All children performed four subtests: walking backwards (WB), moving sideways (MS), hopping for height (HH) and jumping sideways (JS). Age and gender-specific values were established for the Flemish children anno 2008. Overall, the current sample scored significantly worse than their 1974 German counterparts (P<0.001). Score distribution showed 21% of the children being placed in the problematic range of gross motor coordination level. A decline in coordination was observed especially in those tasks relying primarily on coordinative capacities (WB and MS), while improvements or status quo in those tasks relying on strength and speed (JS and HH) were explained by secular trends. We suggest that the KTK is a valuable instrument for the assessment of the gross motor coordination of Flemish children and efforts should be made in order to face the decline in coordination.