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To achieve maximal force output, clinicians and coaches have been experimenting with upper extremity plyometric exercises for years, without sufficient scientific validation of this training method. The goal of this study was to examine the effects of an 8-week course of high volume upper extremity plyometric training on the isokinetic strength and throwing velocity of a group of intercollegiate baseball players. Twenty-four Division I collegiate baseball players (age: 19.7 +/- 1.3 years; height: 183.9 +/- 5.9 cm; mass: 90.7 +/- 10.5 kg) were recruited to participate in this study. Throwing velocity, isokinetic peak torque, isokinetic functional strength ratios, and time to peak torque were measured pre- and posttraining. Subjects were rank-ordered according to concentric internal rotation (IR) strength and were assigned randomly to either the plyometric training group (PLY) or the control group (CON). Training consisted of 6 upper extremity plyometric exercises ("Ballistic Six") performed twice per week for 8 weeks. Subjects assigned to CON performed regular off-season strength and conditioning activities, but did not perform plyometric activities. PLY demonstrated significant increases (p < 0.05) in throwing velocity following 8 weeks of training when compared with CON (83.15 mph [pre] vs. 85.15 mph [post]). There were no statistically significant differences in any of the isokinetic strength measurements between PLY and CON groups pre- to posttraining. Statistically significant differences were seen within PLY for concentric IR and eccentric external rotation (ER) isokinetic strength at 180 degrees x s(-1) and 300 degrees x s(-1); and within CON for eccentric ER isokinetic strength at 300 degrees x s(-1) and concentric IR isokinetic strength at 180 degrees x s(-1). The Ballistic Six training protocol can be a beneficial supplement to a baseball athlete's off-season conditioning by improving functional performance and strengthening the rotator cuff musculature.

Patients with multiple sclerosis (MS) present with varying symptoms that can differ between and within individuals. As new interventions and drug treatments become available to MS patients, it is essential to understand the relationship between fatigue and the variability of functional mobility measures in order to define a meaningful change due to treatment within the MS population. The purpose of this study was to examine the within-day and between-day changes in gait variability for subjects with MS in fresh and fatigued conditions. Walking gait parameters were measured from 20 subjects diagnosed with MS and eight healthy control subjects. Standard deviations of hip, knee and ankle kinematic and kinetic variables were quantified as the measure of variability and analysed with a two-way (group by condition) ANOVA. Results indicated MS subjects had significantly greater hip (P <0.020), knee (P <0.011) and ankle (P <0.034) joint angle variability than control subjects, but variability was not different between conditions. Kinetic variability was not different between groups or conditions. MS subjects in this study walked more slowly than the healthy controls and they also reported more fatigue. Research examining treatment effects within the MS population should account for increased levels of kinematic gait variability.