The effects of ball impact location and grip tightness on the arm, racquet and ball for one-handed tennis backhand groundstrokes.

A torque-driven, 3D computer simulation model of an arm-racquet system was used to investigate the effects of ball impact location and grip tightness on the arm, racquet and ball during one-handed tennis backhand groundstrokes. The stringbed was represented by nine point masses connected to each other and the racquet frame with elastic springs and three torsional spring-dampers between the hand and the racquet were used to represent grip tightness. For each perturbation of nine impact locations and grip tightness, simulations were run for a 50 ms period starting with ball-racquet impact.

Evaluation of a subject-specific, torque-driven computer simulation model of one-handed tennis backhand groundstrokes.

A torque-driven, subject-specific 3-D computer simulation model of the impact phase of one-handed tennis backhand strokes was evaluated by comparing performance and simulation results. Backhand strokes of an elite subject were recorded on an artificial tennis court. Over the 50-ms period after impact, good agreement was found with an overall RMS difference of 3.

Dynamic function of the fibula. Gait analysis evaluation of three different parts of the shank after fibulectomy: proximal, middle and distal.

The purpose of this case study was to investigate the dynamic features of fibular movement to gait pattern by analyzing the gait of individuals with three different parts of the fibula resected. Gait analyses revealed that proximal fibula resection impaired knee stability, whereas distal fibula resection disturbed ankle kinematics significantly. Except a mild secondary quadriceps weakness, middle fibula resection did not cause a significant biomechanical disturbance on gait.

Does bilateral total knee arthroplasty affect gait in women?: comparison of gait analyses before and after total knee arthroplasty compared with normal knees.

We performed gait analysis of 24 patients with bilateral knee osteoarthritis (OA) before, 1 year, and 2 years after bilateral total knee arthroplasty and compared these results to 12 normal controls. Cadence was significantly decreased in OA patients when compared with controls. Step and stride lengths were significantly different preoperatively (shorter) and postoperatively (P < .

Reliability and validity testing of an archery chronometer.

Keeping the arrow velocity constant during consecutive shots and responding to "clicker's fall "are considered to be an important feature of archery performance. A specially designed device called an archery chronometer was developed to measure the reaction time of an archer to clicker's fall, arrow velocity, and external factors that may affect arrow velocity. The purposes of this study were to test (1) the validity of Clicker Reaction Time (CRT) measurer, and (2) the reliability of CRT in accordance with the Flying Time (FT)/Average Speed (AS), temperature (TEMP), wind speed (WS) and wind direction (WD) measurements.

Functional evaluation of intraarticular severely comminuted fractures of the calcaneus with gait analysis.

Twenty-one patients (23 feet) treated nonsurgically for severely comminuted intraarticular fractures of the calcaneus were evaluated prospectively with a clinical scoring scale and computerized gait analysis. All patients had Sanders type III and type IV fractures. The treatment protocol consisted of no closed reduction, immobilization in removable splint, physiotherapy after edema subsided, and weightbearing after 8 weeks.

Comparison of landing maneuvers between male and female college volleyball players.

Objective: To compare differences in kinematic and kinetic parameters of knee, hip and ankle joints between male and female college volleyball players.

Design: Cross-sectional study.

Background: Landing injuries, which usually involve anterior cruciate ligament injuries, are common in volleyball with a higher incidence in females.