Effects of acute whole-body vibration exposure on bat velocity and muscle activity during the baseball swing /by G. Francis """"Cisco"""" Reyes.

Three purposes for this study were (1) to investigate effects of acute WBV exposure and exercise order on bat velocity; (2) to examine relationship between muscular strength and bat velocity; (3) to evaluate the acute effects of WBV exposure on muscle recruitment patterns during the swing. Recreationally-trained male subjects (n = 16; 22 {plusmn} 2 yrs; 181.4 {plusmn} 7.4 cm; 84.7 {plusmn} 9 kg), who possessed previous baseball experience, were tested for 1-RM strength in squat and bench press. Subjects then participated in 4 randomized sessions, each consisting of 3 sets of 5 bat swings. Exercises (upper and lower body dynamic and static movements related to bat swing) with or without WBV exposure were applied following sets 1 and 2. Trials were: Control (CTRL), upper body followed by lower body exercises without WBV (Arm-Leg NOVIB), upper body followed by lower body exercises with WBV (Arm-Leg VIB), and lower body followed by upper body exercises with WBV (Leg-Arm VIB). Electromyography measured muscle activity of six muscles (gastrocnemius, biceps femoris, gluteus maximus, pectoralis major, latissimus dorsi, and triceps brachii) during all swings. Bat velocity was recorded during each swing and averaged across sets. One-way repeated measures ANOVA assessed statistical differences across sets and trials. Linear regressions analyzed relationship between strength and bat velocity. A significant relationship existed between bat velocity and 1-RM squat (r 2 = 0.406, p = 0.008) but not with bench press. The exercise order of Arm-Leg VIB significantly increased bat velocity by 2.6% (p = 0.02). Performing identical order of exercises without vibration (Arm-Leg NOVIB) significantly decreased bat velocity (p = 0.039). Gluteus maximus muscle activity significantly decreased following Arm-Leg VIB exercise order (p = 0.009). It was concluded that leg strength had a direct correlation to bat velocity suggesting that increasing leg strength may be beneficial for increasing bat velocity. Adding vibration exposure to total-body exercises can provide acute enhancements in bat velocity. Also, there appears to be an organized pattern of muscle recruitment order during the baseball swing. This data suggests WBV exercises may enhance bat velocity and perhaps contribute to improving a hitter's performance.Thesis (Ph. D., Physical Education)--University of Idaho, December 2008