THE ASSOCIATION BETWEEN TRUNK ENERGY FLOW AND PEAK SHOULDER DISTRACTION FORCE IN COLLEGIATE SOFTBALL PITCHING

The purpose of the study was to determine the association between trunk energy flow (proximal energy inflow (IF) and distal energy outflow (OF) on the pitching arm side) and peak shoulder distraction force during the acceleration phase of the windmill softball pitch. Fifty-five collegiate softball pitchers participated. Regression analysis revealed proximal energy IF was not associated with peak shoulder distraction force during the acceleration phase of the pitch [F (1,53) = .026; p = .87), r = .02]. Distal trunk OF was also not associated with peak shoulder distraction force during the acceleration phase of the pitch [F (1,53) = .920; p = .342), r = .13]. Thus, it was concluded proximal trunk energy IF and distal trunk energy OF on the pitching arm side are not associated with peak shoulder distraction force during the acceleration phase of the pitch

RELATIONSHIP BETWEEN HIP RANGE OF MOTION AND PITCHING KINEMATICS IN HIGH SCHOOL BASEBALL PITCHERS

The purpose of this study was to examine the association of hip rotational range of motion (ROM) with lower extremity and trunk kinematics in high school baseball pitchers. Twenty-five healthy high school baseball pitchers volunteered (15.9 ± 1.1 years). Passive hip internal rotation (IR) and external rotation (ER) ROM was measured with the pitchers seated using a digital inclinometer. Total hip ROM (IR + ER) was calculated for the stride leg and drive leg. Biomechanical data were collected with a 3-D electromagnetic tracking system while pitchers threw three fastballs. Simple linear regression analysis determined drive and stride leg hip IR, ER, and total ROM did not predict pitching kinematics. Future research should continue identifying parameters associated with altered biomechanics that may place baseball pitchers at increased risk of injury

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

THE RELATIONSHIP BETWEEN TRUNK ENERGY FLOW AND COLLEGIATE SOFTBALL HITTING PERFORMANCE

The purpose of this study was to determine the relationship between trunk energy flow and performance (exit velocity) during collegiate softball hitting. Nineteen collegiate softball athletes (age: 19.6 ± 1.0yrs) performed three maximal effort swings off a pitching machine. Kinematic data were collected using an electromagnetic tracking system. A segmental power analysis was performed to quantify peak rates of trunk energy flow (proximal inflow (IF) and distal outflow (OF) on front and back sides). Regression analyses determined exit velocity was best predicted by peak rate of distal trunk energy OF on the front side. On average, the model showed exit velocity increased by .9 mph for every 100 W increase in distal trunk energy OF on the front side while holding body mass constant

INDIVIDUAL CONSTRAINTS AND TIME SCALE ON JOINT COUPLING PATTERNS IN SOFTBALL PITCHERS

BACKGROUND: Individual constraints such as fatigue may gradually influence a performer’s movement patterns over time. The degree of linkage between joint angles of the throwing arm can help describe the extent that joint actions are coupled. The purpose of this study was to examine changes in joint coupling patterns in softball pitchers at increased pitch counts. METHODS: Eighteen high-school softball pitchers (15±1.6y,1.6±0.2m,77.2±17.0kg) pitched four blocks of twenty-five randomly assigned common pitch types. Randomly determined rest ranging from four to seven minutes was provided between blocks to mimic time between innings of a game. Participants’ kinematics were captured using an electromagnetic tracking system which recorded positional data of sensors placed on body segments. Trials were trimmed from top of the pitch to end of follow through and interpolated 0-100% of the pitch. Each participant’s mean time series data of shoulder, elbow, and wrist sagittal-plane angular motion were determined from three fastball pitches in the first and last blocks. Joint-to-joint time series correlations were performed on the shoulder and elbow, shoulder and wrist, and elbow and wrist. To evaluate if the joint-to-joint correlation coefficients between the first and last blocks were statistically different, correlation coefficients were transformed into Z-scores and compared using Steiger’s Z-tests. RESULTS: The respective correlation coefficients for the first and last blocks were as follows: shoulder-elbow=.44/.34; shoulder-wrist=.68/.61; and elbow-wrist=.32/.25. The strengths and direction of the correlation coefficients ranged from weak to strong and were positive but non-significant (\u3e.05). Differences in joint-to-joint correlation coefficients between the first and last blocks were non-significant: shoulder-elbow; Z-diff=.35,p=.73; shoulder-wrist; Z-diff=.32,p=.75; elbow-wrist; Z-diff=.19,p=.85. CONCLUSIONS: Greater joint coupling (higher coefficient) may represent a strategy to limit motions and simplify the task, whereas a releasing of joint coupling may represent more independent components or movement exploration. This work suggests joint coupling occurs in softball pitching but changes may be minimal at this pitch volume (100 pitches). Additional work identifying the effects of individual constraints on softball pitching is needed to understand workload implications on movement patterns and injury risk

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