Jessica Washington

Acute Hip Abduction Fatigue on Lumbopelvic-Hip Complex Stability in Softball Players

During an overhead throw, the gluteal muscle group stabilizes the lumbopelvic-hip complex (LPHC), leading to efficient energy transfer from the lower to upper extremity. It has been shown that LPHC instability can lead to throwing pathomechanics. The single leg squat has become a common assessment for LPHC stability, and could be used to determine the effects of fatigue on throwing athletes. The purpose of this study was to determine the effects of an acute abduction fatigue protocol on the LPHC of collegiate softball players via the single leg squat assessment of the leg ipsilateral to the throwing arm. Eighteen National Collegiate Athletic Association Division I softball players volunteered (20.5±1.9 years; 169.4±10.0 cm; 72.9±11.5 kg). Each participant performed a single leg squat on the leg ipsilateral to the throwing arm prior to and post side-lying hip abduction fatigue. LPHC and lower extremity kinematics were examined to determine potential effects of fatigue on LPHC stability. There were no significant main effects or interactions of LPHC or lower extremity kinematics during the single leg squat assessments across the fatigue protocol. Based on the current study, an acute bout of fatigue to the hip abductors does not affect LPHC stability in single leg squat execution.

Kinematic differences between hitting off a tee versus front toss in collegiate softball players

Abstract The purpose of this study was to compare kinematics of two hitting conditions: stationary tee and front toss from a practice pitcher. Twenty-two NCAA Division I Collegiate softball players (20.3 ± 1.5 years; 166.6 ± 6.3 cm; 68.0 ± 7.5 kg) participated. Participants executed five maximum effort swings from a stationary tee and five swings from a front toss practice pitcher. Data for each kinematic variable were averaged for the five maximal effort swings of each condition and analyzed using a within-subject repeated measures ANOVA. The front toss condition revealed significantly greater lead knee flexion at foot contact and greater trunk rotation towards the back side at ball contact. The tee condition revealed greater trunk lateral flexion to the back side at foot contact, greater trunk rotation towards the lead side at follow through, and greater pelvis rotation towards the lead side at follow through. This study most significantly indicates that swing mechanics are different between specific training methods; therefore, athletes should implement techniques most applicable to a competition setting such as the front toss.

Assessment of lumbopelvic–hip complex instability and segmental sequencing amongst softball athletes

ABSTRACT The purpose of this study was to examine the effects of lumbopelvic–hip complex (LPHC) instability on segmental sequencing and the maximum velocities during the overhead throw. Fifty softball athletes (164.0 ± 104.0 cm, 65.6 ± 11.3 kg, 16.3 ± 3.8 years) classified as either college, high school or youth performed three 60 ft overhead throws then executed bilateral single leg squats (SLS). Kinematics were recorded using an electromagnetic tracking system. Participants were classified as ‘unstable’ if they displayed knee valgus greater than 15° at 45° knee flexion in the descending phase of the SLS. One-way ANOVAs and Bonferonni post-hoc tests revealed no significant differences between stability groups in segmental sequencing and maximum velocities amongst the college, high school and youth participation level. When all athletes were grouped together regardless of age, there were still no significant differences observed between groups. These findings imply that segmental sequencing and maximum velocities are not a function of LPHC stability amongst this specific group of athletes. Additionally, the SLS may not accurately quantify LPHC stability in regards to throwing. The authors recommend that future studies repeat these methods amongst different athletic populations and continue to evaluate different clinical tests for LPHC stability.

Differences in Throwing Kinematics among Youth Baseball Pitchers and Football Quarterbacks

The purpose of this study was to examine throwing kinematics of youth baseball pitchers and football quarterbacks. Eighteen pitchers (13.6 ± 1.3 years; 169.3 ± 8.0 cm; 62.3 ± 10.2 kg) and fifteen quarterbacks (14.3 ± 1.6 years; 174.9 ± 7.9 cm; 69.1 ± 14.0 kg) participated. Pitchers threw three fastballs to a catcher (46 ft; 14.0 m), while quarterbacks threw three 15 yard (13.7 m) passes to a receiver. Baseball pitchers displayed significantly greater trunk flexion at maximum external rotation (MER), ball release (BR) and maximum internal rotation (MIR) (p<0.001, p=0.003, p=0.007); as well as greater trunk rotation opposite throwing arm side at BR (p=0.048). Football quarterbacks displayed greater trunk rotation to throwing arm side at MER (p=0.002); shoulder horizontal adduction at FC (p=0.004); shoulder external rotation at BR (p=0.036); and elbow flexion at FC and MER (p=0.018, p=0.044). Trunk kinematic differences may be the result of pitchers throwing from a mound versus flat ground, just as upper extremity kinematic differences could be the result of the weight and shape of the ball.

Hamstring and Gluteal Muscle Activation During the Assessment of Dynamic Movements

Recently, sports medicine professionals have shown interest in using dynamic movement assessments to help identify biomechanical risk factors for musculoskeletal injury. Thus the purpose of this study was to propose two movements (single leg step down and single leg lateral hop) that could predict injury and determine if these proposed movements elicited muscle activation of the hamstrings and gluteals. Surface electromyography was employed and muscle activations of the hamstrings and gluteus medius muscles were classified as strong during both the single leg step down (SLSD) and single leg lateral hop (SLLH). Both the hamstrings and gluteus medius muscles are associated with musculoskeletal injury. The SLSD and SLLH cause significantly high muscle activation of both these muscle groups and should be considered for use in dynamic movement assessments.