The relationship between balance and pitching error in college baseball pitchers

The objective of the study was to examine the relationship between balance and pitching error in college baseball pitchers. Sixteen college baseball pitchers, 9 National Association of Intercollegiate Athletics (NAIA) and 7 National Collegiate Athletic Association (NCAA) Division III, participated in the study. Balance ability, expressed as average sway velocity (deg.s(-1)), during dominant leg unilateral stance with eyes open and eyes closed was quantified for each subject utilizing the Balance Master System 7.04 (long force plate). Additionally, each subject underwent sensory organization testing on the SMART EquiTest System providing information regarding the effective use of the somatosensory, visual, and vestibular inputs. Pitching error was assessed with a high-speed video camera recorder during spring practice. A JUGS radar gun measured pitch velocity. The mean pitching error was 37.50 cm with a mean pitch velocity of 78 miles.h(-1) (35 m.s(-1)). No significant correlation was demonstrated between unilateral stance eyes open and pitching error (r = -0.24; p = 0.36) or unilateral stance eyes closed and pitching error (r = -0.29; p = 0.27). A significant negative correlation was demonstrated between sensory organization test 5 and pitching error (r = -0.50; p = 0.05) and between sensory organization test 5/1 and pitching error (r = -0.50; p = 0.05). Additionally, unilateral stance eyes closed demonstrated a positive correlation with pitch velocity (r = 0.52; p = 0.04). The results reveal that low levels of vestibular input utilization may lead to high levels of pitching error in college baseball pitchers.     

Lumbopelvic control and pitching performance of professional baseball pitchers

This study assessed the correlation between lumbopelvic control during a single-leg balancing task and in-game pitching performance in Minor-League baseball pitchers. Seventy-five healthy professional baseball pitchers performed a standing lumbopelvic control test during the last week of spring training for the 2008 and 2009 seasons while wearing a custom-designed testing apparatus, the "Level Belt." With the Level Belt secured to the waist, subjects attempted to transition from a 2-leg to a single-leg pitching stance and balance while maintaining a stable pelvic position. Subjects were graded on the maximum sagittal pelvic tilt from a neutral position during the motion. Pitching performance, number of innings pitched (IP), and injuries were compared for all subjects who pitched at least 50 innings during a season. The median Level Belt score for the study group was 7°. Two-sample t-tests with equal variances were used to determine if pitchers with a Level Belt score <7° or ≥7° were more likely to perform differently during the baseball season, and chi-square analysis was used to compare injuries between groups. Subjects scoring <7° on the Level Belt test had significantly fewer walks plus hits per inning than subjects scoring ≥7° (walks plus hits per inning pitched, 1.352 ± 0.251 vs. 1.584 ± 0.360, p = 0.013) and significantly more IP during the season (IP, 78.89 ± 38.67 vs. 53.38 ± 42.47, p = 0.043). There was no significant difference in the number of pitchers injured between groups. These data suggest that lumbopelvic control influences overall performance for baseball pitchers and that a simple test of lumbopelvic control can potentially identify individuals who have a better chance of pitching success.     

Influence of shoulder abduction and lateral trunk tilt on peak elbow varus torque for college baseball pitchers during simulated pitching

Elbow varus torque is a primary factor in the risk of elbow injury during pitching. To examine the effects of shoulder abduction and lateral trunk tilt angles on elbow varus torque, we conducted simulation and regression analyses on 33 college baseball pitchers. Motion data were used for computer simulations in which two angles-shoulder abduction and lateral trunk tilt-were systematically altered. Forty-two simulated motions were generated for each pitcher, and the peak elbow varus torque for each simulated motion was calculated. A two-way analysis of variance was performed to analyze the effects of shoulder abduction and trunk tilt on elbow varus torque. Regression analyses of a simple regression model, second-order regression model, and multiple regression model were also performed. Although regression analyses did not show any significant relationship, computer simulation indicated that the peak elbow varus torque was affected by both angles, and the interaction of those angles was also significant. As trunk tilt to the contralateral side increased, the shoulder abduction angle producing the minimum peak elbow varus torque decreased. It is suggested that shoulder abduction and lateral trunk tilt may be only two of several determinants of peak elbow varus torque.     

Lower-extremity ground reaction forces in collegiate baseball pitchers

The purpose of this study was to investigate ground reaction forces (GRF) in collegiate baseball pitchers and their relationship to pitching mechanics. Fourteen healthy collegiate baseball pitchers participated in this study. High-speed video and force plate data were collected for fastballs from each pitcher. The average ball speed was 35 ± 3 m/sec (78 ± 7 mph). Peak GRFs of 245 ± 20% body weight (BW) were generated in an anterior or braking direction to control descent. Horizontal GRFs tended to occur in a laterally directed fashion, reaching a peak of 45 ± 63% BW. The maximum vertical GRF averaged 202 ± 43% BW approximately 45 milliseconds after stride foot contact. A correlation between braking force and ball velocity was evident. Because of the downward inclination and rotation of the pitching motion, in addition to volume, shear forces may occur in the musculoskeletal tissues of the stride limb leading to many of the lower-extremity injuries seen in this athletic population.     

The impact of pitch counts and days of rest on performance among major-league baseball pitchers

Although the belief that overuse can harm pitchers is widespread, there exists little evidence to show that the number of pitches thrown and the days of rest affect future performance and injury among adults. The purpose of this study is to quantify the effects of pitches thrown and the days of rest on pitcher performance. We examined performances of major-league baseball starting pitchers from 1988 to 2009 using fractional polynomial multiple regression to estimate the immediate and cumulative impact of pitches thrown and the days of rest on performance, while controlling for other factors that likely affect pitcher effectiveness. Estimates indicate each pitch thrown in the preceding game increased earned run average (ERA) by 0.007 in the following game. Each pitch averaged in the preceding 5 and 10 games increased the ERA by 0.014 and 0.022, respectively. Older pitchers were more sensitive to cumulative pitching loads than younger pitchers were, but they were less affected by pitches thrown in the preceding game. Rest days were weakly associated with performance. In summary, we found that there is a negative relationship between past pitches thrown and future performance that is virtually linear. The impact of the cumulative pitching load is larger than the impact of a single game. Rest days do not appear to have a large impact on performance. This study supports the popular notion that high pitching loads can dampen future performance; however, because the effect is small, pitch-count benchmarks have limited use for maintaining performance and possibly preventing injury.     

Shoulder joint movement of the non-throwing arm during baseball pitch—comparison between skilled and unskilled pitchers

The shoulder of a non-throwing arm during a baseball pitch must be in a constant position while the shoulder of the throwing arm moves in a nearly circular path around it. However, it has not been investigated whether a skilled pitch requires less shoulder-joint movement. It was hypothesized that pitchers with less shoulder movement of the non-throwing arm can be considered to have higher skill and to attain higher initial ball velocity. Nine baseball pitchers were used as subjects. The coach classified them into a skilled and an unskilled group. The pitching motions were recorded using two high-speed cameras. The time series of three-dimensional landmark coordinates of the shoulder joint of the non-throwing arm during the baseball pitch were calculated using the direct linear transformation method. The shoulder-joint movement (SJM) index, which expresses the movement (displacement) of the shoulder joint of the non-throwing arm quantitatively, was proposed to compare the SJM at different skill levels and investigate the relationship between SJM and initial ball velocity. The SJM of the skilled pitchers was smaller than that of the unskilled pitchers, and the smaller value of the SJM led to faster initial ball velocity. The data suggest that the less SJM of the non-throwing arm is required to attain a skilled pitch and higher initial ball velocity.     

Kinematic and kinetic comparison of baseball pitching among various levels of development

Proper biomechanics help baseball pitchers minimize their risk of injury and maximize performance. However previous studies involved adult pitchers only. In this study, 23 youth, 33 high school, 115 college, and 60 professional baseball pitchers were analyzed. Sixteen kinematic (11 position and five velocity), eight kinetic, and six temporal parameters were calculated and compared among the four levels of competition. Only one of the 11 kinematic position parameters showed significant differences among the four levels, while all five velocity parameters showed significant differences. All eight kinetic parameters increased significantly with competition level. None of the six temporal parameters showed significant differences. Since 16 of the 17 position and temporal parameters showed no significant differences, this study supports the philosophy that a child should be taught ‘proper’ pitching mechanics for use throughout a career. Kinetic differences observed suggest greater injury risk at higher competition levels. Since adult pitchers did not demonstrate different position or temporal patterns than younger pitchers, increases in joint forces and torques were most likely due to increased strength and muscle mass in the higher level athlete. The greater shoulder and elbow angular velocities produced by high-level pitchers were most likely due to the greater torques they generated during the arm cocking and acceleration phases. The combination of more arm angular velocity and a longer arm resulted in greater linear ball velocity for the higher level pitcher. Thus, it appears that the natural progression for successful pitching is to learn proper mechanics as early as possible, and build strength as the body matures.     

High school and college baseball pitchers response and glove movements to line drives

The timing of glove movements used by baseball pitchers to catch fast approaching balls (i.e., line drives) was examined in two tests to determine the responses and temporal characteristics of glove movements in high school and college baseball pitchers. Balls were projected toward the head of participants at 34.8 m.s-1 (78 mph) on average in an indoor test and at speeds approaching 58.1 m.s-1 (130 mph) in a field test. Pitchers caught over 80% and 15% of the projected balls in the indoor and field tests, respectively. Analyses of glove responses indicated that all pitchers could track the line drives and produce coordinated glove movements, which were initiated 160 ms (+/-47.8), on average, after the ball was launched. College pitchers made initial glove movements sooner than high school pitchers in the field test (p=0.012). In contrast, average glove velocity for pitchers increased from 1.33 (+/-0.61) to 3.45 (+/-0.86) m.s-1 across the tests, but did not differ between experience levels. Glove movement initiation and speed were unrelated, and pitchers utilized visual information throughout the ball's flight to catch balls that approached at speeds exceeding the estimated speeds in competitive situations.     

A relationship between attractiveness and performance in professional cyclists

Females often prefer to mate with high quality males, and one aspect of quality is physical performance. Although a preference for physically fitter males is therefore predicted, the relationship between attractiveness and performance has rarely been quantified. Here, I test for such a relationship in humans and ask whether variation in (endurance) performance is associated with variation in facial attractiveness within elite professional cyclists that finished the 2012 Tour de France. I show that riders that performed better were more attractive, and that this preference was strongest in women not using a hormonal contraceptive. Thereby, I show that, within this preselected but relatively homogeneous sample of the male population, facial attractiveness signals endurance performance. Provided that there is a relationship between performance-mediated attractiveness and reproductive success, this suggests that human endurance capacity has been subject to sexual selection in our evolutionary past.     

A comparison of throwing kinematics between youth baseball players with and without a history of medial elbow pain

Risk factors in throwing factors associated to little league elbow have not been adequately explored. Whether these factors also affect the players' performance is also important to elucidate while modifying throwing pattern to reduce injury. The purpose of this study was to compare the differences in throwing kinematics between youth baseball players with or without a history of medial elbow pain (MEP) and to determine the relationship between their throwing kinematics and ball speed. Fifteen players with previous MEP were matched with 15 healthy players by age, height and weight. Throwing kinematics was recorded by an electromagnetic motion analysis system. A foot switch was used for determining foot off and foot contact. Ball speed was recorded with a sports radar gun. The group with a history of MEP demonstrated less elbow flexion angle at maximum shoulder external rotation and had more lateral trunk tilt at ball release compared to the healthy group. The group with a history of MEP also had faster maximum upper torso rotation velocities, maximum pelvis rotation velocities and ball speeds. Maximum shoulder external rotation angle (r = 0.458, P = 0.011), elbow flexion angle at maximum shoulder external rotation (r = -0.637, P = 0.0003), and maximum upper torso rotation velocity (r = 0.562, P = 0.002) had significant correlation with ball speed. Findings of this study can be treated as elbow injury-related factors that clinicians and coaches can attend to when taking care of youth     

The effects of taping on scapular kinematics and muscle performance in baseball players with shoulder impingement syndrome

PurposeThis study aimed to investigate the effect of elastic taping on kinematics, muscle activity and strength of the scapular region in baseball players with shoulder impingement.ScopeSeventeen baseball players with shoulder impingement were recruited from three amateur baseball teams. All subjects received both the elastic taping (Kinesio Tex^TM) and the placebo taping (3 M Micropore tape) over the lower trapezius muscle. We measured the 3-dimensional scapular motion, electromyographic (EMG) activities of the upper and lower trapezius, and the serratus anterior muscles during arm elevation. Strength of the lower trapezius was tested prior to and after each taping application. The results of the analyses of variance (ANOVA) with repeated measures showed that the elastic taping significantly increased the scapular posterior tilt at 30° and 60° during arm raising and increased the lower trapezius muscle activity in the 60–30° arm lowering phase (p < 0.05) in comparison to the placebo taping.ConclusionsThe elastic taping resulted in positive changes in scapular motion and muscle performance. The results supported its use as a treatment aid in managing shoulder impingement problems.     

The relationship between maternal age and chromosome size in autosomal trisomy.

The pattern of maternal age-specific incidence of autosomal trisomy in spontaneous abortions was examined for each chromosome for which a sufficient number of trisomies was observed. This included chromosomes 2, 4, 7-10, 13-16, 18, and 20-22. The rate of increase after age 30 for each of the small chromosomes (groups D-G) was similar, with the exception of chromosome 16, which showed a significantly shallower rate. The C group chromosomes tended to have an intermediate rate of increase after age 30, with the exception of chromosome 7, which had a pattern similar to the smaller chromosomes. The larger chromosomes (2 and 4) had the smallest rate of increase. There was a significant relationship between chromosome size and rate of increase after age 30 (after excluding chromosome 16), but not with rate of increase before age 30. The results suggest that autosomal trisomies may be of heterogeneous origin, with a maternal age-related factor associated with chromosome size and other sources unrelated to chromosome size. Additional evidence for and against this hypothesis is discussed.     

The relationship between the osmotic fragility of human erythrocytes and cell age

Erythrocytes in a normal blood sample are hemolyzed over a range of hypotonic salt concentrations. In order to investigate the relationship between the distribution of osmotic fragilities and the distribution of cellular ages, the osmotic fragility has been compared with three indices of cellular age. The activity of glutamic-oxalacetic transaminase (GOT) and the percentage hemoglobin A_1C were measured in samples hemolyzed in different hypotonic salt concentrations. The osmotic fragility curve was also obtained for cells of different density separated by centrifugation. These experiments indicate that the fragility distribution is not an accurate reflection of the distribution of cellular ages. The mean fragility for older cells is higher than that of younger cells. However, cellular aging does not produce a gradual increase in osmotic fragility. Instead, it seems to produce changes which can both increase and decrease the fragility, resulting in a broader distribution of fragilities with some of the older cells actually less fragile than the younger ones.     

The relationship between whole bone stiffness and strength is age and sex dependent

Accurately estimating whole bone strength is critical for identifying individuals that may benefit from prophylactic treatments aimed at reducing fracture risk. Strength is often estimated from stiffness, but it is not known whether the relationship between stiffness and strength varies with age and sex. Cadaveric proximal femurs (44 Male: 18–78 years; 40 Female: 24–95 years) and radial (36 Male: 18–89 years; 19 Female: 24–95 years) and femoral diaphyses (34 Male: 18–89 years; 19 Female: 24–95 years) were loaded to failure to evaluate how the stiffness-strength relationship varies with age and sex. Strength correlated significantly with stiffness at all sites and for both sexes, as expected. However, females exhibited significantly less strength for the proximal femur (58% difference, p < 0.001). Multivariate regressions revealed that stiffness, age and PYD were significant negative independent predictors of strength for the proximal femur (Age: M: p = 0.005, F: p < 0.001, PYD: M: p = 0.022, F: p = 0.025), radial diaphysis (Age: M = 0.055, PYD: F = 0.024), and femoral diaphysis (Age: M: p = 0.014, F: p = 0.097, PYD: M: p = 0.003, F: p = 0.091). These results indicated that older bones tended to be significantly weaker for a given stiffness than younger bones. These results suggested that human bones exhibit diminishing strength relative to stiffness with aging and with decreasing PYD. Incorporating these age- and sex-specific factors may help to improve the accuracy of strength estimates.