Browsing by Author "Surmon, Sean Henry"

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    Reciprocal muscle group and functional dynamic stability ratios of the hamstrings and quadriceps muscle groups during maximal isokinetic concentric and eccentric contractions
    (Stellenbosch : Stellenbosch University, 1999-12) Surmon, Sean Henry; Blaauw, J. H.; Stellenbosch University. Faculty of Education. Dept. of Sport Science.
    ENGLISH ABSTRACT: The concentric hamstring quadriceps reciprocal muscle group ratio has been the focus of a very large part of studies involving isokinetic dynamometry. The main aim of this study was to reevaluate the functional relevance of this ratio and explore a strength ratio between maximal eccentric strength of the hamstrings and the concentric strength of the quadriceps muscle groups, referred to as the functional dynamic stability ratio. At the same time the inter-relationship between the eccentric and concentric strength of the same muscle group (critical deficit ratio) was investigated. As background a detailed discussion of research concerning the conventional hamstring quadriceps ratio and the biomechanics of the knee joint and musculature was presented. The importance of the eccentric strength of the hamstring muscle group regarding functional muscle action and anterior cruciate ligament stability was also discussed. The functional dynamic stability ratio was hypothesised to be a 1: 1 ratio due to the simultaneous concentric quadriceps and eccentric hamstring muscle contraction during walking, jogging and running activities. The bilateral concentric and eccentric peak torque of the hamstrings and quadriceps muscle groups of 45 (N=45) rugby players were evaluated using a Kin-ComĀ© isokinetic dynamometer. The calculated average concentric reciprocal muscle group ratio was (0.64, SD=0.15) and eccentrically (0.61, SD=0.15). The average functional dynamic stability ratio resulted to 0.77 (SD= 0.14) for the left leg and 0.79 (SD= 0.16) for the right leg. Critical deficit ratios were 1.26 (SD=0.26) for the right hamstring, 1.33 (SD=0.210 right quadriceps, 1.28 (SD=0.21) lefts hamstring and 1.29 (SD=0.17) for the left quadriceps muscle groups. Values obtained were in accordance to that of available research. The functional dynamic stability ratio was found to be striving towards a 1:1 ratio to achieve optimal knee joint and hamstring integrity.