No abstract

The purpose of this study was to examine the results of the two major methods of treatment of complete acromioclavicular separation: surgery and nonsurgical techniques. Twenty male patients with complete acromioclavicular separation within the preceding 13 months were retrospectively examined and tested for recovery of shoulder strength and function. Comparisons were conducted between 10 of the patients who had been treated nonsurgically (Group 1), and 10 who had been treated surgically (Group 2). An additional group of 10 uninjured male subjects as controls was also tested for comparison of strength between dominant and nondominant limbs (Group 3). All of the patients were tested for strength of both shoulders using the Kin-Com isokinetic dynamometer, for shoulder flexibility using the Leighton flexometer, and for grip strength using a standard grip dynamometer. A questionnaire concerning patient evaluation of the injury was also administered to all of the subjects. The majority of strength and flexibility tests showed no significant differences between the nonsurgical and surgical groups. The nonsurgical group was statistically superior to the surgical group in the following test scores: eccentric abduction (fast speeds), concentric external rotation (slow speeds), eccentric external rotation (fast), eccentric abduction (slow), and flexibility in external rotation. These findings generally indicated that the nonsurgical treatment of a third-degree acromioclavicular separation is superior in restoring normal shoulder function in the 1st year following injury.

This study was conducted to determine some fitness parameters of two elite handball players, including the current world champion, and also to determine some of the time-motion characteristics of the game of hand-ball. The VO2 max values of the two players were found to be similar (53.1 and 55.2 ml/kg/min), while the world champion was substantially higher on the anaerobic power test and in peak ventilation scores. The results of heart rate monitoring of these players indicated that the mean game heart rate was dependent on several external factors, such as the skill level of each player, the fitness level of each player, the length of the rallies, and the player in control of the rally. The mean heart rate for the world champion was 149 beats per minute (bpm) during each game, while that for the other skilled player was 163.6 bpm, which represented 80% and 88% of maximum, respectively. The average length of each rally was 9 seconds, and the mean pause time (between rallies) was 10 seconds, producing a work-to-test ratio of approximately 1:1. The ball was found to be in play for an average of 47.3% of the total mean game time of 17 minutes. Each player was found to take approximately 350 strokes per match, with the world champion, and eventually the winner, taking a greater number of serves. Handball training should consist of interval training at an intensity of at least 80% of maximum heart rate, with a work-to-rest ratio of 1:1 and an emphasis on 10 second intervals.

A mathematical model has been developed to study the control mechanisms of human trunk movement during walking. The trunk is modeled as a base-excited inverted pendulum with two-degrees of rotational freedom. The base point, corresponding to the bony landmark of the sacrum, can move in three-dimensional space in a general way. Since the stability of upright posture is essential for human walking, a controller has been designed such that the stability of the pendulum about the upright position is guaranteed. The control laws are developed based on Lyapunov's stability theory and include feedforward and linear feedback components. It is found that the feedforward component plays a critical role in keeping postural stability, and the linear feedback component, (resulting from viscoelastic function of the musculoskeletal system) can effectively duplicate the pattern of trunk movement. The mathematical model is validated by comparing the simulation results with those based on gait measurements performed in the Biomechanics Laboratory at the University of Manitoba.

The arm swing in hockey skating can have a positive effect on the forces produced by each skate, and the resulting velocity from each push off. The main purpose of this study was to measure the differences in ground reaction forces (GRFs) produced from an anteroposterior versus a mediolateral style hockey skating arm swing. Twenty-four elite-level female hockey players performed each technique while standing on a ground-mounted force platform, and all trials were filmed using two video cameras. Force data was assessed for peak scaled GRFs in the frontal and sagittal planes, and resultant GRF magnitude and direction. Upper limb kinematics were assessed from the video using Dartfish video analysis software, confirming that the subjects successfully performed two distinct arm swing techniques. The mediolateral arm swing used a mean of 18.38° of glenohumeral flexion/extension and 183.68° of glenohumeral abduction/adduction while the anteroposterior technique used 214.17° and 28.97° respectively. The results of this study confirmed that the mediolateral arm swing produced 37% greater frontal plane and 33% less sagittal plane GRFs than the anteroposterior arm swing. The magnitudes of the resultant GRFs were not significantly different between the two techniques; however, the mediolateral technique produced a resultant GRF with a significantly larger angle from the direction of travel (44.44°) as compared to the anteroposterior technique (31.60°). The results of this study suggest that the direction of GRFs produced by the mediolateral arm swing more closely mimic the direction of lower limb propulsion during the skating stride.