THE RELATIONSHIP BETWEEN STRIDE MECHANICS AND SHOULDER DISTRACTION FORCE IN COLLEGIATE SOFTBALL PITCHERS

The purpose of this study was to determine the relationship between stride mechanics and shoulder distraction force in softball pitchers. Sixty-three collegiate softball pitchers (age: 20.1 ± 1.3 yrs, height: 173.3 ± 7.4 cm, weight: 79.7 ± 11.7 kg) participated and threw three maximal effort fastballs for a strike. Kinematic data were collected using an electromagnetic tracking system with a sampling frequency of 100 Hz. Regression analysis revealed a significant positive relationship between stride length and shoulder distraction force [R2 = .11; F (1, 61) = 7.345, p = .009], where stride length accounted for 11% of the variation in shoulder distraction force. Specifically, shoulder distraction force increased by .94 N/kg for every 10% increase in stride length normalized as a percentage of body height

Soil Chemistry Properties Under Two Different Management Practices: Clipped Saint Augustine Grass Lawn and Annually Burned Cajun Prairie

Prescribed burning every two or more years is the recommended management practice to remove unnecessary invasive plants and to enhance the regrowth of desirable plants for the development of a fire-dependent plant community native to southwestern Louisiana. A portion of Saint Augustine grass lawn at Louisiana State University at Eunice (LSUE) was converted into a Cajun Prairie restoration plot in 1989. Since 1991, the adjacent lawn has been clipped weekly, whereas the prairie has been burned every January. The objective of this study was to determine the soil chemical properties of clipped lawn and burned prairie plots. Each plot (12 m x 104 m) had four blocks (replications). Soil samples from the 0-10 cm depth were taken from each block for each plot in December 2002, March 2003, and June 2003. They were analyzed in the laboratory for soil chemical properties: pH, organic carbon (OC), electrical conductivity (EC) as a measure of soluble salts, phosphorus (P), potassium (K), calcium (Ca), magnesium (Mg), sodium (Na), iron (Fe), zinc (Zn) and copper (Cu). Extractable soil P, Ca, Mg and Na were significantly greater in the burned prairie than in the clipped lawn. In the burned prairie from December to June, Fe increased, whereas pH, EC, P, K, Na, Cu, and Zn decreased. The results suggest that the annually burned restored Cajun Prairie provided greater nutrient deposition into the soil than the clipped Saint Augustine lawn

PEAK RATE OF TRUNK ENERGY OUTFLOW DIFFERS BETWEEN PITCH TYPES IN SOFTBALL PITCHERS

In softball players, it is unclear how certain pitch types may increase the risk of injury. The purpose of this study was to determine energy flow differences in the trunk and upper-arm segments between pitch types. Twenty-three softball pitchers participated. Absolute values of trunk energy inflow (IF) and outflow (OF), and upper arm IF, as well as segment energy flow when normalized to pitch speed were assessed in three pitch types. Differences between trunk energy OF were found between fastballs compared to curveballs and dropballs. When normalized to pitch speed, trunk energy OF only differed between fastballs and dropballs. For the upper arm, absolute differences were found between the fastball and curveball. Similar rates of humerus IF between the fastball and dropball and less trunk outflow in the dropball may indicate increased upper extremity demands in the dropball

EFFICIENCY INDEX USED TO ASSESS SHOULDER STRESS IN COLLEGE SOFTBALL PITCHERS THROUGHOUT A SIMULATED GAME

Shoulder distraction forces in softball pitching are known to have a positive impact on performance yet a negative impact on musculoskeletal health. The purpose of this study was to assess changes in shoulder stress across innings pitched using Efficiency Arm-Stress Index (EASI) scores. Motion capture was used on collegiate softball pitchers pitching a simulated game. Peak shoulder distraction force was obtained using inverse dynamics procedures and used to calculate an EASI score (fastball velocity divided by peak shoulder distraction force in percent body weight). A RM·ANOVA revealed inning had no effect on EASI score (F[6,7]=1.28, p=0.286). Understanding a pitcher’s efficiency score may help shape individual pitching loads. Future work should investigate clinically meaningful changes in efficiency scores and mechanisms behind low efficiencies

INFLUENCE OF IN-GAME SITUATION ON BALL RELEASE PARAMETERS IN DIVISION 1 COLLEGE BASEBALL PITCHERS

BACKGROUND: Success at high competition levels often hinges on performing well during high pressure (leverage) situations. Advanced baseball analytics enable teams to quantify the pressure of in-game situations, and markerless motion capture makes it possible to capture in-game biomechanical data. Research suggests consistent pitch release parameters improve performance across a season. Therefore, this study aimed to compare fastball release parameters and pitch velocity in college baseball pitchers between in-game high and low Leverage Index (LI) situations. METHODS: In-game markerless motion capture data (300Hz) for fifty-six NCAA Division 1 baseball pitchers (1.89±0.1m; 92.7±8.9kg) were analyzed. Pitch velocity and hand position (relative to the middle of the pitching rubber) in the anterior/posterior, superior/inferior, and medial/lateral directions at ball release were analyzed. Play-by-play data were scraped for LI components (score, innings, outs, and baserunners) and matched to the appropriate pitch. LI is an estimate of in-game pressure that measures the potential change in win expectancy and is calculated as the sum of the weighted change in win probability divided by the average win probability added per swing. Each pitcher’s highest and lowest LI fastball pitches were used for within-pitcher comparison. A one-way repeated measures multivariate analysis of variance (RM·MANOVA) determined if release parameters and pitch velocity differed between high and low LI situations (α = .05). RESULTS: Descriptive statistics (high LI mean ± SD vs. low LI mean ± SD) for the parameters analyzed are as follows: LI (2.8±1.6 vs. 0.4±0.5), pitch velocity (40.45±3.2 vs. 40.54±1.4 m/s), anterior/posterior hand position (1.72±0.1 vs. 1.73±0.1 m), medial/lateral hand position (0.52±0.2 vs. 0.47±0.2 m), and superior/inferior hand position (1.79±0.2 vs. 1.82±0.2 m). The RM·MANOVA revealed no significant differences in release parameters between high and low LI pitches (F4,52 =.322, p=.862). CONCLUSION: While prior research identified a relationship between consistency in the release position and season long performance, these release parameters are not influenced by high or low pressure (leverage) situations. Additional comparisons of high and low leverage situations, as determined by LI, should include analysis of additional kinematics, ball flight metrics, and ball/strike outcomes

KINEMATIC PREDICTORS OF INGAME FASTBALL VELOCITY IN NCAA DIVISION I BASEBALL PITCHERS

BACKGROUND: Pitch velocity is a key measure of fastball performance in baseball pitchers. The kinematics related to ball velocity are traditionally examined in laboratory settings with marker-based motion capture systems. However, limited research exists investigating their influence on in-game performance. The purpose of this study was to identify the kinematic predictors of in-game fastball velocity in collegiate baseball pitchers. METHODS: Kinematic data from 57 NCAA Division I pitchers (height: 1.89 ± 0.06m, mass: 93.1 ± 1.18kg) were collected at 300hz using an eight-camera markerless motion capture system (KinaTrax, Boca Raton, FL). Data were processed and filtered using propriety KinaTrax software. Kinematics were measured at foot contact (FC) (stride length, shoulder rotation, shoulder horizontal abduction, and shoulder abduction), maximum shoulder external rotation (MER) (shoulder rotation and elbow flexion), ball release (BR) (elbow flexion, shoulder abduction, trunk flexion, trunk lateral flexion, and lead knee flexion). Maximum knee extension velocity as well as trunk and pelvis rotation velocity were also included for analysis. Fastball velocity was recorded using a TrackMan (Scottsdale, AZ) V3 Game Tracking unit. The average of each subject’s first five fastballs thrown in a game was used for analysis. A backward multiple linear regression (α = .05) was used to identify the kinematic predictors of in-game fastball velocity. RESULTS: The average fastball velocity from the cohort was 40.9 ± 1.22m/s (91.4 ± 2.73mph). After the backward elimination (cutoff of p ≥ 0.05), three predictors explained 17.7% of the variance in fastball velocity (F(3,54)=3.81, R2 =.177, p=.014). As fastball velocity increases by 1 m/s (2.2 mph), max lead knee angle velocity increases by 0.003°/s (β=0.003, t=2.46, p=.017), max trunk rotational velocity increases by 0.005°/s (β=0.005, t=2.40, p=.020), or lead knee flexion at BR decreases by 0.027° (β=-0.027, t=-2.33, p=.024), while all other variables are held constant. CONCLUSION: The findings show greater stride knee extension at BR, maximum stride knee extension velocity, and maximum trunk rotational velocity are predictors of in-game fastball velocity. Investigating in-game data provided similar results to those of prior laboratory studies, while a higher pitch velocity, fewer significant variables, and lower coefficient of determination were noted

COMPARISON OF IN-GAME TRUNK AND UPPER EXTREMITY KINEMATICS BETWEEN PITCH TYPES IN COLLEGIATE BASEBALL PITCHERS

BACKGROUND: Baseball pitchers commonly experience shoulder and elbow injuries. Pitch type has been identified as a possible risk factor, but previous biomechanical studies were limited to laboratory analysis. The purpose of this study was to compare in-game trunk and upper extremity kinematics between fastballs, breaking balls, and changeups in collegiate baseball pitchers. METHODS: Twenty-four NCAA Division I collegiate baseball pitchers (1.9±0.1m; 94.5±10.5kg) who threw at least five in-game fastballs, breaking balls, and changeups were included in this study. Trunk and throwing-arm kinematics were recorded during games using a markerless motion capture system (300Hz). A TrackMan V3 Game Tracking unit defined pitch type. Kinematics of each pitcher’s first five pitches of each pitch type were averaged for analysis. A repeated measures multivariate analysis of variance (MANOVA) was used to assess within-subject differences between each pitch type (α = .05). The variables of interest were shoulder abduction at foot contact (FC), shoulder horizontal abduction at FC, shoulder external rotation at FC, shoulder maximum external rotation (MER), elbow flexion at MER, maximum shoulder rotational velocity, lateral trunk tilt at ball release (BR), shoulder abduction at BR, and elbow flexion at BR. RESULTS: The MANOVA revealed differences in kinematics between pitch types (F18,78 = 3.49, p\u3c.001). Follow-up univariate testing revealed significant differences across pitch types for MER (F2 = 3.77, p=.03) along with shoulder abduction (F2 = 6.27, p=.004), lateral trunk tilt (F2 = 11.63, p\u3c.001), and elbow flexion (F2 = 5.06, p =.01), all at BR. Pairwise comparisons revealed that fastballs had greater MER than breaking balls (mean within-subjects difference: 1.5±2.6°, p=.03). At BR, changeups resulted in greater shoulder abduction than fastballs (1.2±2.0°, p=.03) and breaking balls (1.5±2.3°, p=.01). Changeups produced less lateral trunk tilt at BR than fastballs (-3.6±4.8°, p=.003) and breaking balls (-2.9±4.2°, p=.008) and greater elbow flexion at BR than breaking balls (1.2±1.7°, p=.006). All other variables were not significantly different (p \u3e.10). CONCLUSION: Collegiate pitchers had in-game kinematic differences between pitch types, especially at BR. It is unknown if these differences alter injury risk, but they may impact performance by showing the batter which pitch type will be thrown

Vitamin D receptor gene polymorphisms and Parkinson's disease in a population with high ultraviolet radiation exposure.

IntroductionA high prevalence of vitamin D deficiency has been reported in Parkinson's disease (PD). Epidemiologic studies examining variability in genes involved in vitamin D metabolism have not taken into account level of exposure to ultraviolet radiation (UVR). We examined whether exposure to UVR (as a surrogate for vitamin D levels) and variations in the vitamin D receptor gene (VDR) are associated with PD.MethodsWithin a geographical information system (GIS) we linked participants' geocoded residential address data to ground level UV data to estimate historical exposure to UVR. Six SNPs in VDR were genotyped in non-Hispanic Caucasian subjects.ResultsAverage lifetime UVR exposure levels were >5000 Wh/m(2), which was higher than levels for populations in previous studies, and UVR exposure did not differ between cases and controls. Homozygotes for the rs731236 TT (major allele) genotype had a 31% lower risk of PD risk (OR=0.69; 95% CI=0.49, 0.98; p=0.04 for TT vs. TC+CC). The rs7975232 GG (minor allele) genotype was also associated with decreased risk of PD (OR=0.63; 95% CI=0.42, 0.93; p=0.02 for GG vs. TG+TT). The association between PD risk and a third locus, rs1544410 (BsmI), was not statistically significant after adjustment for covariates, although there was a trend for lower risk with the GG genotype.ConclusionsThis study provides initial evidence that VDR polymorphisms may modulate risk of PD in a population highly exposed to UVR throughout lifetime

Vitamin D receptor gene polymorphisms and cognitive decline in Parkinson's disease.

We and others have suggested that vitamin D receptor gene (VDR) polymorphisms influence susceptibility for Parkinson's disease (PD), Alzheimer's disease (AD), mild cognitive impairment (MCI) or overall cognitive functioning. Here we examine VDR polymorphisms and cognitive decline in patients with PD. Non-Hispanic Caucasian PD patients (n=190) in the Parkinson Environment Gene (PEG) study were successfully genotyped for seven VDR polymorphisms. Cognitive function was assessed with the Mini-Mental State Exam (MMSE) at baseline and at a maximum of three follow-up exams. Using repeated-measures regression we assessed associations between VDR SNP genotypes and change in MMSE longitudinally. PD cases were on average 67.4years old at diagnosis and were followed for an average of 7.1years into disease. Each additional copy of the FokI A allele was associated with a 0.115 decrease in the total MMSE score per year of follow-up (β=-0.115, SE(β)=0.05, p=0.03) after adjusting for age, sex, education and PD duration. The effect on MMSE by the FokI A allele was comparable in absolute magnitude to the effect for disease duration in years prior to first interview (β=-0.129 per year, SE(β)=0.08, p=0.13), and years of education (β=0.118 per year, SE(β)=0.03, p<0.001). When LD/LED use and PD subtype were added to the model, the effect of the FokI A allele on total MMSE score was magnified (β=-0.141, SE(β)=0.05, p=0.005). Results point to Fokl, a functional VDR polymorphism, as being associated with cognitive decline in PD. Future studies examining the contributions of the vitamin D metabolic pathway to cognitive dysfunction in PD are needed