INTRODUCT1ON: Ski racing demands the dynamic generation of high levels of torque. Isokinetic leg strength tests are almost always open kinetic chain (OKC) tests. Neumayr et al. (2003) found concentric (con) hamstring:quadriceps (H:Q) ratios of 0,57-0.60 for World Cup alpine ski racers. Recent tests with Austrian elite skiers in our lab using an isokinetic closed kinetic chain (CKC) device showed very different con H:Q ratios (0.14-0.36). To our knowledge there is no published work which compares H:Q ratios in isokinetic OKC and CKC. METHOD: Twelve athletes of the Skigymnasium Stams (<$7, $5; 16±0.8 years; 68.2±8.0 kg; 173.0±7.1 cm) were tested on a Con-Trex leg press (CKC) and on a multi-joint (OKC) for unilateral concentric and eccentric (ecc) extension and flexion strength. Isokinetic measurements were performed at knee angles of 85° to 120° for CKC and 90° to 170° for OKC (180° = full knee extension) and velocity setting of 0.4/0.4m/s (CKC) and 120°/s (OKC). All recorded strength values were corrected for the effect of gravity. The statistical analysis was performed using a Pearson Correlation (p<0.05) in SPSS 15.0. RESULTS: The H:Q ratios of the OKC and CKC are shown in Table 1. No significant correlations of the H:Q ratios between open and closed kinetic chain were found. DISCUSSION: Traditional OKC tests simply compare the influence of quadriceps and hamstrings on the knee joint. The inclusion of the hip joint in the CKC radically changes the flexor:extensor ratio because of the pre-dominance of the hip extensors. Additional OKC measurements with the athletes of Stams, in which the hip was isolated, confirmed this (con flexor:extensor ratio=0.08-0.25). In alpine skiing the majority of the work is performed by knee and hip muscles utilizing the SSC. Such physiological demands can be better simulated with CKC testing and functional ratios should be used. This is in accordance with Aagaard et al. (1998), who stated that the agonist-antagonist strength relationship may be better described by con/ecc and ecc/con ratios. In order to assess the balancing nature of the hamstrings in ACL deficient knees the H:Q ratio should be tested under ecc/con conditions (Dvir, 2004). CONCLUS1ON: CKC tests are more ski specific and not comparable to OKC results. The inclusion of the hip joint in CKC tests necessitates replacing H:Q ratio with flexor:extensor ratio.
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