DEPTH JUMP TRAINING AND THE VOLLEYBALL SPIKE

The dynamics of movement often combine high strength demands with speed requirements. We speak of the rise time of a force. or the power (work done per unit of time) exhibited in the perfo-rmance of a task. Success in numerous sports is dependent upon the ahility to meet the strength-speed demands; and this practical need leads us to questions about how one improves dynamic capahilities. It has been suggested that plyometric training is a means to this end (Verhoshanski, 1968)

INFLUENCE OF TRADITIONAL AND NON-TRADITIONAL ENTRIES ON FIGURE SKATING JUMPS

The choice of performing jumps from traditional entries or nontraditional entries are left to the discretion of the skater. The purpose of this study was to examine the influence of non-traditional entries on the kinematics of two figure skating jumps using a simple quantitative tool available to coaches. It was hypotheisized that non-tradional entries would alter jump kinematics. Ten skilled figure skaters were videotaped while performing toe loops or salchows with both traditional and non-tradional entires. Kinematic variables were determined with Dartfish. Results indicated that non-traditional entries had significantly more jump height and ankle plantar flexion at landing in the toe loop, and signifcantly more horizontal displacment in the salchow. Coaches may wish to examine these subtlies to determine a skater’s readiness to practice non-traditional entries

Landing development: A first look at young children

The purpose of this study was to examine sagittal and frontal views of children (n=14) aged 4-9 landing from a maximal effort vertical jump to begin a description of landing development. Video records (collected at 30 frames/sec) of the jump and landing were viewed frame by frame with Windows Movie Maker and analyzed with a simple scoring system validated to detect improper movements during landing. Findings indicated that this stop-landing task challenged balance as most landings included a step, straddled foot position, and a wide stance. Mechanisms for force absorption (knee and hip flexion) tended to occur more often in landings of older children, but incidences of knee valgus also increased with age. Further investigation may establish developmental expectations for landing and help coaches and physical educators correct potentially harmful patterns as children age and pursue more competitive sport

THE EFFECTS OF LOAD MASS ON THE KINEMATICS OF STIFF-LEGGED DEADLIFT

The purpose of this study was to investigate the effects of load mass on the kinematics of lower extremity joint movements during the stiff-legged deadlift (SLD) lift exercise. Five participants performed the SLD at 40%, 60%, and 80% of their estimated 1 repetition maximum. Measurements of the joint angle and angular velocity of the spine, hip, knee, and ankle were analyzed to understand the influence of various load masses in the SLD lifting technique. No statistical significant differences were found in the joint angles and angular velocities of the spine and lower extremity between different loads. Therefore, this study suggests that performing stiff-legged exercise up to 80% is safe to perform as long as the participants are experienced with this lifting technique

THE EFFECTS OF MIDSOLE CONSTRUCTION ON BOWLING DELIVERY

The purpose of this study was to examine the effects of midsole construction on the mechanics of bowling delivery. Twelve participants performed five candle bowling ball deliveries in three footwear conditions (barefoot, traditional and modified with E-TPU). Both kinematic and kinetic analyses were conducted. The results of the barefoot condition showed hip, knee and ankle joints at 92.3 ± 9.9°, 133.0 ± 14.5°, and 111.6 ± 11.2°, respectively, which were not significantly different from the modified condition of 93.9 ± 9.9° (p =.289) 132.1 ± 14.5° (p =.758), and 117.7 ± 9.4° (p =.123). Also, no significant difference was found in peak vertical force to body weight ratio. These findings provide a preliminary understanding on the effects of footwear on bowling delivery. Future studies are warranted to evaluate 3D motion analysis with experienced bowlers at the bowling alley

THE EFFECTS OF FATIGUE ON SOFTBALL PITCHER FROM PITCHING MULTIPLE GAMES

The purpose of this study was to examine the effects of fatigue on softball pitching from pitching back to back games. Players were asked to throw 15 balls in each inning for seven innings and for a total of two games. The results showed fastball’s velocity in the first inning of the first game (25.4 ± 2.5 m/s) had significantly decreased after a game and a half (24.3 ± 2.7 m/s; p = 0.00). Hence, this study suggests that the pitchers started to show signs of fatigue after this amount of pitches (165 pitches), so softball coaches may take this into consideration and make necessary pitching change. Given the established relationship between fatigue and injury in pitchers, the Amateur Softball Association may use this information to implement a pitch count to protect softball pitchers from overuse injur

KINETIC ANALYSES OF E-TPU MATERIAL IN BOWLING FOOTWEAR

The purpose of this study was to examine the vertical ground reaction force between the traditional bowling shoes made of rubber midsole and the modified bowling shoes made of E-TPU midsole. All shoes underwent both static and dynamic performance testing on a force platform. The preliminary results indicated that the bowling footwear with the E-TPU material provided lower amount of vertical ground reaction force in both static and dynamic testing, which may potentially be beneficial to bowlers to minimize lower extremity injury. Future studies are warranted to evaluate the internal joint forces of bowling delivery mechanics with the E-TPU material footwear