With the exception of shoe mileage, which is likely a response to rather than a risk factor for AKP, these results should prove useful to clinicians in identifying runners at risk for anterior knee pain.

Load carriage is a key element in dismounted military operations. Load carriage requirements in the field regularly exceed 50% of lean body mass (LBM) and have only rarely been studied. Therefore, our purpose was to determine the metabolic and motivational effects of heavy loads (30-70% LBM) during constant-rate "road" marching on a treadmill. Ten healthy male Army officers carried loads of 30%, 50%, and 70% LBM in an all-purpose, lightweight, individual, carrying equipment pack for 30 minutes, at a speed of 6 km/h. Oxygen consumption (VO2), ventilation, heart rate (HR), respiratory exchange ratio, rating of perceived exertion (RPE), and Self-Motivation Inventory scores were recorded at each trial. Significant increases were observed for VO2, ventilation, and HR between the trials. RPE significantly increased for the 70% LBM trial, compared with the 30% and 50% trials. No significant differences were seen in respiratory exchange ratio or Self-Motivation Inventory scores. Increasingly heavy loads carried in a rucksack resulted in increased VO2, RPE, and HR; therefore, increasing the load that a soldier is required to carry may negatively affect road march performance.

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The bench press is one of the most popular weight training exercises. Although most training regimens incorporate multiple repetition sets, there are few data describing how the kinematics of a lift change during a set to failure. To examine these changes, recreational lifters (10 men and 8 women) were recruited. The maximum weight each subject could bench press (1RM) was determined. Subjects then performed as many repetitions as possible at 75% of the 1RM load. Three-dimensional kinematic data were recorded and analyzed for all lifts. Statistical analysis revealed that differences between maximal and submaximal lifts and the kinematics of a submaximal lift change as a subject approaches failure in a set. The time to lift the bar more than doubled from the first to the last repetition, causing a decrease in both mean and peak upward velocity. Furthermore, the peak upward velocity occurred much earlier in the lift phase in these later repetitions. The path the bar followed also changed, with subjects keeping the bar more directly over the shoulder during the lift. In general, most of the kinematic variables analyzed became more similar to those of the maximal lift as the subjects progressed through the set, but there was considerable variation between subjects as to which repetition was most like the maximal lift. This study shows that there are definite changes in the lifting kinematics in recreational lifters during a set to failure and suggests it may be particularly important for coaches and less-skilled lifters to focus on developing the proper bar path, rather than reaching momentary muscular failure, in the early part of a training program.

As part of the physical education program at the United States Military Academy, all cadets complete a movement training course designed to develop skills and improve performance in military-related physical tasks as well as obstacle navigation. The purpose of this study was to determine if completion of this course would also result in changes in jump-landing technique that reduce the risk of anterior cruciate ligament (ACL) injury. Analysis of landing mechanics on a two-footed jump landing from a height of 30 cm with a three-dimensional motion capture system synchronized with two force plates revealed both positive and negative changes. Video assessment using the Landing Error Scoring System (LESS) revealed an overall improved landing technique (p=.001) when compared to baseline assessments. The studied military movement course appears to elicit mixed but overall improved lower extremity jump-landing mechanics associated with risk for ACL injury.

The purpose of this study was to determine the vertical and lateral forces applied to the bar during a maximal and a submaximal effort bench press lifts. For this study, 10 male and 8 female recreational lifters were recruited (mean height: 1.71 ± 0.08 m; mass: 73.7 ± 13.6 kg) and were asked to perform a maximal and submaximal (80% of maximal lift) bench press. These lifts were performed with a bar instrumented to record forces applied to it, via the hands, in the vertical direction and along the long axis of the bar. To determine the position of the bar and timing of events, 3D kinematic data were recorded and analyzed for both lifts. The subjects in this study averaged a maximal lift of 63 ± 29 kg (90 ± 31% bodyweight). The peak vertical force was 115 ± 22% (percentage of load), whereas for the submaximal condition it was 113 ± 20%; these forces were statistically different between conditions; they were not when expressed as a percentage of the load (p > 0.05). During all the lifts, the lateral forces were always outward along the bar. The lateral force profile was similar to that of the vertical force, albeit at a lesser magnitude. During the lift phase, the peak lateral force was on average 26.3 ± 3.9% of the vertical force for the maximal lift and 23.7 ± 3.9% of the vertical force for the submaximal lift. Given that the amount of force applied laterally to the bar was a similar percentage of vertical force irrespective of load, it appears that the generation of lateral forces during the bench press is a result of having the muscles engaged in generating vertical force.

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