Kinesiology Research & Publications

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Browsing Kinesiology Research & Publications by Author "Aagaard, Per"

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    Lower Limb Asymmetry in Mechanical Muscle Function: A Comparison Between Ski Racers With and Without ACL Reconstruction
    (Scandinavian Journal of Medicine and Science in Sports, 2016) Herzog, Walter; Jordan, Matthew; Aagaard, Per
    Due to a high incidence of anterior cruciate ligament (ACL) re-injury in alpine ski racers, the aim was to assess functional asymmetry in the countermovement jump (CMJ), squat jump (SJ) and leg muscle mass in elite ski racers with and without anterior cruciate ligament reconstruction (ACL-R). Elite alpine skiers with ACL-R (n=9; 26.2±11.8 months post-op) and uninjured skiers (n=9) participated in neuromuscular screening. Vertical ground reaction force during the CMJ and SJ was assessed using dual force plate methodology to obtain phase-specific bilateral asymmetry indices (AI) for kinetic impulse (CMJ and SJ phase-specific kinetic impulse AI). Dual X-Ray absorptiometry (DXA) scanning was used to assess asymmetry in lower body muscle mass. Compared to controls, ACL-R skiers had increased AI in muscle mass (P<0.001), kinetic impulse AI in the CMJ concentric phase (P<0.05) and the final phase of the SJ (P<0.05). Positive associations were observed between muscle mass and AI in the CMJ concentric phase (r=0.57, P<0.01) as well as in the late SJ phase (r=0.66, P<0.01). Future research is required to assess the role of the CMJ and SJ phase-specific kinetic impulse asymmetry index as a part of a multi-faceted approach for improving outcome following ACL-R in elite ski racers.
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    Rapid Hamstring/Quadriceps Strength in ACL Reconstructed Elite Alpine Ski Racers
    (Medicine and science in sports and exercise, 2016) Herzog, Walter; Jordan, Matthew; Aagaard, Per
    Due to the importance of hamstrings (HAM) and quadriceps (QUAD) strength for anterior cruciate ligament (ACL) injury prevention, and the high incidence of ACL injury in ski racing, HAM and QUAD maximal and explosive strength was assessed in ski racers with and without ACL reconstruction (ACL-R).
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    A Return to Skiing Envelope of Function for Anterior Cruciate Ligament Reconstructed Elite Alpine Ski Racers
    (Science and Skiing VI, 2016) Herzog, Walter; Jordan, Matthew; Aagaard, Per
    Elite alpine ski racing comprises bidirectional turning with forceful concentric but predominantly eccentric contractions that create large quadriceps muscle loading and hamstrings/quadriceps muscle co-contraction (4, 10). Ski racing also occurs in an unpredictable environment where skiers are at an increased risk for lower body injury, especially to the knee joint and the anterior cruciate ligament (ACL) (2, 3, 8, 15). Unlike field sports, there are no sex-differences in ACL injury rates due to the preclusion of sex-related risk factors resulting from the large forces and unique mechanisms of ACL injury (8, 15).