The purpose of the study was to investigate the effects of fatigue on lower extremity joint kinematics, and kinetics during repetitive drop jumps. Twelve recreationally active males (n = 6) and females (n = 6) (nine used for analysis) performed repetitive drop jumps until they could no longer reach 80% of their initial drop jump height. Kinematic and kinetic variables were assessed during the impact phase (100 ms) of all jumps. Fatigued landings were performed with increased knee extension, and ankle plantar flexion at initial contact, as well as increased ankle range of motion during the impact phase. Fatigue also resulted in increased peak ankle power absorption and increased energy absorption at the ankle. This was accompanied by an approximately equal reduction in energy absorption at the knee. While the knee extensors were the muscle group primarily responsible for absorbing the impact, individuals compensated for increased knee extension when fatigued by an increased use of the ankle plantar flexors to help absorb the forces during impact. Thus, as fatigue set in and individuals landed with more extended lower extremities, they adopted a landing strategy that shifted a greater burden to the ankle for absorbing the kinetic energy of the impact.
Joshua T. Weinhandl, Jeremy D. Smith and Eric L. Dugan
Ronald Davis, Charlotte Sanborn, David Nichols, David M. Bazett-Jones and Eric L. Dugan
Bone mineral density (BMD) loss is a medical concern for individuals with spinal cord injury (SCI). Concerns related to osteoporosis have lead researchers to use various interventions to address BMD loss within this population. Whole body vibration (WBV) has been reported to improve BMD for postmenopausal women and suggested for SCI. The purpose of this case study was to identify the effects of WBV on BMD for an individual with SCI. There were three progressive phases (standing only, partial standing, and combined stand with vibration), each lasting 10 weeks. Using the least significant change calculation, significant positive changes in BMD were reported at the trunk (0.46 g/cm2) and spine (.093 g/cm2) for phase 3 only. Increases in leg lean tissue mass and reduction in total body fat were noted in all three phases.
Tim L.A. Doyle, Ronald W. Davis, Brendan Humphries, Eric L. Dugan, Bryon G. Horn, Jae Kun Shim and Robert U. Newton
A number of researchers have long questioned systems used for classifying athletes with disabilities. Wheelchair basketball players have gained much attention from researchers. Despite this, no change to the NWBA classification system has been made since it was first adopted in 1984. This study investigated the NWBA classification system. At two summer basketball camps, 46 players were tested to assess player sprint performance and stratification under the NWBA medical classification system. The group consisted of Class 1, 2, and 3 players. Electronic timing gates were used to collect 20 meter sprint-times. Results indicate that Class 1 players were significantly slower compared to Class 2 and 3 players (p < .05) with no difference between Class 2 and 3. The results of this study support a change to this system.