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Team lifting is required in many workplaces, particularly where heavy and awkward lifts are prevalent. Despite the known risk factors associated with team lifting, it remains under researched, with almost no 4-person lifting studies. The purpose of this thesis was to investigate how members of a 4-person team coordinate their actions during a lifting task that involved an unexpected release from a single team member. It involved a novel approach to investigating the mechanisms associated with joint action and whether these mechanisms may alert the remaining lifters that a release is imminent, where the goal was to elicit an unexpected response from the group. Data collected for a previous team lifting study was used. Six groups of four male participants (n = 24) performed 30 lifts with a constructed 60 kg lifting apparatus designed to transition between a rectangular (2 x 4 ft or 61 x 122 cm) and a square (2 x 2 ft or 61 x 61 cm) configuration. A total of 8 trials (4 per configuration) were designated as “drop trials”. Vertical force at the hands and right-side electromyography (EMG) of the biceps brachii (BB), anterior deltoid (AD), upper trapezius (UT), and the lumbar erector spinae (LES) was collected for each participant. Means and standard deviation of vertical force was compared from the pre-drop phase for both drop and non-drop (lift) trials. No significant differences were found between drop and non-drop trials during the pre-drop phase. A comparison of time to peak force and time to peak muscle activity was performed for lifters adjacent to the release position. These times were compared against a 25 to 150 ms window to determine whether the muscle activity was considered reflexive or anticipatory to the dropped load. A small proportion of the peak muscle activity values were considered anticipatory (6 BB and 2 LES), suggesting that while it is possible for the dropper to disguise the release, perhaps joint action provides insight to the other lifters. The complex mechanisms that support joint action, their connection to biomechanics and their role in team lifting warrants further research in order to determine how large of a role they might play. / Thesis / Master of Science in Kinesiology

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The purpose of this study was to investigate the effect of same-day strength training on bat swing velocity of male collegiate baseball players. Sixteen male baseball players engaged in a preseason strength training program designed by the team's strength and conditioning coach. All subjects were tested for bat swing peak velocity immediately prior to ball impact for a non lifting day (NLD) by recording 10 swings with 30 seconds of rest in between swings. The next day, a lifting day (LD), all subjects tested on the NLD were tested four to six hours after the morning lifting session with the same amount of swings and rest. Six Vicon MX13+ infrared cameras (Vicon-Colorado, Centennial, Colorado), running at 400 Hz, were placed around the swinging area using Nexus 1.2 imaging software to download and determine bat swing peak velocity immediately prior to ball impact. The average of the top six bat swing peak velocity test results, for each subject, was compared to measures taken on the NLD and LD. A matched t-test revealed a significant difference in bat swing peak velocity between a NLD and a LD. A mean bat swing difference between NLD (69.18) and LD (70.86) of 1.68 was statistically different at better than the .05 level [p =.021]. This study suggests that male collegiate baseball players should be able to engage in a designed strength training program with a positive effect, and without any negative effect, on bat swing peak velocity when a strength training session is scheduled on the same day as a baseball competition.

Analysis of elite performances is important to elucidate the characteristics of effective weightlifting technique contributing to the highest level of achievement. The general technique of the weightlifting movements is well established. However, it is also apparent that weightlifting technique can differ based on athlete characteristics. Thus, existing technical models may not accurately reflect current technique of top performers or be applied generically to athletes of different skill, size, sex, or ability. Therefore, the purpose of this descriptive study was to update the scientific knowledge of snatch technique of top international weightlifters. This study used video analysis to determine barbell trajectory and kinematics of 319 successful snatch attempts from two major international competitions. Relative frequencies of barbell trajectory types differed based on competition, sex, category, and ranking. No statistical differences were observed among the top-three performers for either sex for most kinematic variables, and there were no overall discernible patterns of effect size differences for individual or clusters of kinematic variables. The results of this study indicate that weightlifting success can be achieved with a variety of technique profiles.

M. S.

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Twenty-five sedentary female volunteers, 18-30 years of age, were studied to determine the effects of an endurance running program on leg strength gains from a weight training program. Subjects were randomly assigned to one of three groups: a weight training group (W), a weight training plus running group (RW), or a control group (C). The subjects trained three days per week, approximately one hour per day, for nine weeks. The RW group ran for 25 min then weight trained for 30 min, whereas the W group weight trained for one hour. Subjects were tested for one-repetition maximum (l-RM) pre-training, at two week intervals during training, and post-training. Thigh girth (midpoint [MG] and 1.18 cm above the patella [AP]) and percent body fat were measured pre- and post-training, only weekly on a calibrated scale. Body weight was measured. Significant improvements in isotonic leg strength of 56% for W and 66% for RW were observed, with no difference between the groups. W and RW also achieved a significantly greater isotonic leg strength than the C group. The experimental groups had a significantly greater posttest AP as compared to the C group. No significant differences were observed over the experimental period in MG, percent body fat and body weight of any of the groups. In conclusion, the running program used in the present study did not interfere with leg strength or girth gains achieved through weight training. These results are in contrast to those reported in other studies which found that aerobic training impaired strength gains. / Master of Science