Altered Cervical Spine Position Results in Decreased Eccentric Shoulder Rotation Strength.

Overhead athletes require strenuous shoulder activity in nonneutral cervical spine positions to eccentrically decelerate the throwing/striking arm following ball release/contact. We therefore aimed to compare eccentric shoulder rotation strength through a 90° arc between neutral and rotated positions. Fifty-two participants (19 M, 34 F 170±10 cm; 73±18 kg, 21.9±2.9 years) without shoulder or cervical spine pathology participated. Isokinetic eccentric shoulder rotation strength was measured through a 90° arc with the shoulder elevated 90° in frontal plane (frontal plane), and 45° anterior to the frontal plane (scapular plane) in neutral and rotated cervical spine positions. Cervical spine position was obtained by instructing participants to maximally rotate their respective side. Frontal plane eccentric external rotated strength differed between neutral and contralaterally positions in the first 10° of the motion, near forearm vertical (p+=+0.029). Internal rotation strength differed between neutral and contralaterally rotated positions from 55-60° external rotation (p+=+0.004). Scapular plane eccentric external rotation differed between cervical positions between 21-67° shoulder external rotation (p<0.001). Scapular plane internal rotation strength differed between cervical positions between 22-60° shoulder external rotation (p<0.001). In populations requiring strenuous use of their shoulders in altered cervical spine positions, sports medicine clinicians should consider including strength testing that reflects the functional positions of their patients during an orthopedic examination.

Energy Flow during Baseball Machine Hitting.

The primary aims of the study were to perform a descriptive analysis of hitting energetics off a pitching machine and to compare between the rear- and lead-side lower and upper extremities. Eighty-five high school to minor league baseball athletes participated. Five full-effort swings off a pitching machine with the fastest exit velocity were used for analysis. Energy flow was quantified using a segment power analysis. Wilcoxon signed-rank test revealed significant differences between rear- and lead-side energetics during both swing phases. During the stride, the rear knee and shoulder generated more energy than the lead side. Throughout the swing phase the lead knee, hip, and elbow generated more energy than the rear side, but at the shoulder the rear side generated significantly more energy than the lead. Most intriguing, differing energy transfer directions between the rear and lead knee and shoulder joints were reported. Furthermore, descriptive results revealed energy is predominantly transferred across the knee, shoulder, and elbow joints, while the hips primarily display energy generation. The descriptive nature of the study provides a foundation for future research and can be used as a resource for training personnel to design effective training protocols aimed at maximizing performance.

Altered Cervical Spine Position Results in Decreased Shoulder Rotation Strength.

BACKGROUND: Strength testing of shoulder rotation is commonly used in clinical examinations of the shoulder. People prone to shoulder injury, such as overhead athletes and manual trade workers, place their shoulders under tremendous amounts of stress when the cervical spine is in nonneutral positions. If these nonneutral cervical spine positions result in decreased shoulder strength, it may help explain the etiology of the high prevalence of shoulder injuries in these populations. Given standard clinical strength assessments are performed with a neutral cervical spine, an investigation into the effects of cervical spine rotation is warranted. QUESTIONS/PURPOSES: We sought to compare isokinetic shoulder rotation strength while in a neutral position with rotated cervical spine positions, specifically (1) with the cervical spine rotated contralaterally with the shoulder elevated in the frontal plane and (2) with the cervical spine rotated ipsilaterally and the shoulder elevated in the scapular plane. METHODS: A convenience sample of 52 individuals (height 170 ± 10 cm; weight 73 ± 18 kg, age 21 ± 2 years; 18 males, 34 females), without shoulder or cervical spine pathology participated in this study. Participants were screened for eligibility via questionnaire. Concentric shoulder internal and external rotation torque was measured through a 90° arc on an isokinetic dynamometer with the shoulder elevated 90° in the frontal plane, and again 45° anterior to the frontal plane (scapular plane). Two repetitions were performed in a single testing session with the participant's cervical spine in neutral in both planes, maximally rotated contralaterally in the frontal plane, and maximally rotated ipsilaterally with the shoulder in the scapular plane; the second repetition was used for analysis. The testing order was randomized. Data were imported into a platform for statistical parametric mapping analysis (a technique that allows data from the entire arc of motion to be compared with data from another arc to identify differences in the wave form) to compare strength between positions throughout 90° arc of motion. RESULTS: Rotating the cervical spine contralaterally with the shoulder in the frontal plane resulted in a decrease in external (2.24 Nm or 12% average difference; p < 0.001) and internal (2.22 Nm or a 6% average difference; p = 0.02) rotation strength with the forearm within 15° and 20° of the vertical position. Rotating the cervical spine ipsilaterally with the shoulder in the scapular plane resulted in a decrease in external rotation strength (1.27 Nm or a 6% average difference; p < 0.001) throughout nearly all the motion, with peaks approximately 20° and 60° from the horizontal position, and internal rotation strength (1.78 Nm or 5% average difference; p < 0.001) the last 60° towards the horizontal position. CONCLUSION: Patient populations who require strenuous use of their shoulders in altered cervical spine positions may be at increased risk for injury from decreased shoulder rotator strength. CLINICAL RELEVANCE: Clinicians should assess shoulder strength in the position the patient requires to use their shoulder because cervical spine position may cause weakness that would be missed in standard testing positions.

Influence of a Pre-throwing Protocol on Range of Motion and Strength in Baseball Athletes.

Though chronic overhand throwing is known to result in range of motion and strength adaptations, there is limited research regarding interventions for maintenance of these characteristics. Therefore, the purposes of this study were to explore the use of a pre-throwing protocol focusing on lumbopelvic-hip complex musculature in high school baseball players and examine its effects on shoulder and hip range of motion and isometric strength over the course of a season. Four exercises were added to the intervention team's warm-up routine. The control and intervention teams' passive bilateral hip and shoulder range of motion and isometric strength were assessed pre/post-season. A multivariate analysis of variance revealed significant differences in delta scores between the teams for multiple shoulder and hip range of motion and isometric strength variables. Key results were the intervention team lost significantly more stride hip external rotation but gained more isometric strength than the control team. The intervention team was also able to better maintain shoulder range of motion than the control team. Practitioners should use the results of this study and consider incorporating exercises that target lumbopelvic-hip complex musculature into their current training program.

Relationship Between Humeral Energy Flow During the Baseball Pitch and Glenohumeral Stability.

Researchers suggest that motion deriving energy from the more proximal segments of the body is important to reduce injury susceptibility. However, limited clinical assessments have been associated with efficient energy flow within a complex movement such as the baseball pitch. This research aimed to determine the relationship between glenohumeral stability as determined by the closed kinetic chain upper extremity stability test and energy transfer into and out of the humerus during the baseball pitching motion. Kinematic and kinetic data were collected at 240 Hz on twenty-four baseball pitchers. Participants performed the closed kinetic chain upper extremity stability test prior to throwing three fastballs at game speed to a catcher with the fastest fastball used for analysis. Spearman's Rho were used to examine relationships between energy flow in and out of the humerus with glenohumeral stability as determined by the average score and normalized stance width during the closed kinetic chain upper extremity stability test. There was a significant negative correlation between the average score and normalized peak power leaving the humerus (r s[22]=-0.42, p=0.04). This result provides preliminary support for the use of the closed kinetic chain upper extremity stability test as a clinical assessment of a pitcher's ability to efficiently transfer energy within the upper extremity during the pitch.

Glenohumeral and Hip Range of Motion in Youth Softball Athletes.

The purpose of this study was to compare measures of bilateral shoulder and hip range of motion (ROM) between youth softball pitchers and position players. Fifty-two youth softball athletes (12.7±2.1 yrs.; 160.28±10.98 cm; 59.31±15.07 kg) participated. Bilateral hip and shoulder ROM were measured among pitchers (n=29) and position players (n=23). A 2 (pitcher/position player) × 2 (dominant/non-dominant) ANOVA was performed for both internal and external rotation ROM for the shoulder and hip. Paired sample t-tests were also conducted to examine side-to-side differences in total ROM. Data revealed a significant interaction between position and side dominance. Specifically, position players have significantly more non-dominant shoulder external rotation ROM (106.92°± 9.14°) than pitchers (100.12°± 11.21°). There were no significant differences between throwing and non-throwing sides. It is important that coaches and clinicians are aware of these adaptations between overhand and underhand throwing in order to properly develop conditioning and rehabilitation programs to alleviate injury susceptibility and cater to position-specific demands. Additionally, the current data suggest many of the functional adaptations seen within older populations are not fully developed until after youth.

Lumbopelvic-Hip Complex and Scapular Stabilizing Muscle Activations During Full-Body Exercises With and Without Resistance Bands.

Wasserberger, KW, Downs, JL, Barfield, JW, Williams, TK, and Oliver, GD. Lumbopelvic-hip complex and scapular stabilizing muscle activations during full-body exercises with and without resistance bands. J Strength Cond Res 34(10): 2840-2848, 2020-Inefficient sequencing in the kinetic chain has been linked to decreased performance and increased injury risk. Resistance band usage is very common in baseball/softball due to accessibility and low cost. However, resistance band use has primarily focused on the rotator cuff and surrounding shoulder musculature, thereby ignoring the rest of the kinetic chain. Currently, it is unclear whether resistance bands are effective tools for training musculature outside the throwing extremity. Thus, the purpose of this study was to examine muscle activations of the lumbopelvic-hip complex (LPHC) and scapular stabilizing musculature during 4 full-body exercises with and without the use of a resistance band. Twenty healthy, active individuals (174.39 ± 1.58 cm; 74.10 ± 1.75 kg; 21.85 ± 1.13 years) participated. Data were collected through surface electromyography for the LPHC and scapular stabilizing musculature during 4 full-body exercises with and without a resistance band. Statistical analyses were used to determine significant differences in activation levels between exercises and within exercises between conditions. Data showed a significant difference on muscle activation based on the interaction between resistance band usage and exercise choice (Λ = 0.276, F24, 136.92 = 3.19, p < 0.001). Adding a resistance band was effective in increasing muscle activation within the scapular stabilizing musculature. Conversely, the use of a resistance band was not as effective in increasing the activation of LPHC musculature. Future studies should investigate exercises that increase LPHC musculature activation. Coaches and clinicians can use these results to make more informed decisions when prescribing exercises to athletes for performance enhancement and rehabilitation.

On discretising continuous data for subgroup analysis in baseball pitching and alternative analytical methodologies.

There is a plethora of research attempting to contrast high- and low-velocity pitchers to identify traits to target for increasing velocity. However, pitch velocity exists on a continuum. Therefore, our purpose is to display the analytical discrepancies between creating velocity subgroups and leaving velocity as a continuous variable by examining the influence of ball velocity on elbow valgus torque. Motion capture data for 1315 actively competing pitchers were retrospectively extracted from a private database. We compared three analytic methods: (1) linear regression of valgus torque on ball velocity, (2) t-test between low- and high-velocity groups formed by a median split, and (3) t-test between very low- and very high-velocity groups formed by upper and lower velocity quartiles. Linear regression indicates ball velocity influenced valgus torque (p < 0.001, R2 = 0.280). Median splitting reduced the predictability of ball velocity on valgus torque (p < 0.001, R2 = 0.180). Conversely, extreme group splitting artificially inflated the effect size (p < 0.001, R2 = 0.347). We recommend sports biomechanics researchers not discretise a continuous variable to form subgroups for analysis because (1) it distorts the relationship between the variables of interest and (2) a regression equation can be used to estimate the dependent variable at any value of the independent variable, not just the group means.

Usage and acceptability of data normalization in baseball pitching.

In baseball pitching biomechanics, kinetic values are commonly ratio 'normalised' by dividing by mass or mass*height to allow for comparison between athletes of different sizes. However, creating a normalised ratio variable should meet certain statistical assumptions. Our purpose was to determine if elbow valgus torque predicted by pitching velocity is influenced by normalisation using regression model comparison with and without normalised torque values. Motion capture data for youth to professional pitchers (n = 1988) were retrospectively analysed. Normalisation assumptions were tested by comparing linear regression models to analogous models with an intercept fixed at zero and by examining remaining correlations between the confounding variable and new, normalised variable. Both mass (p < 0.001) and mass*height (p < 0.001) normalisation did not remove their respective relationship with torque. After accounting for mass or mass and height, velocity predicted 10% of variance in elbow valgus torque, whereas velocity predicted 59% of mass normalised torque and 45% of mass*height normalised torque. Ratio normalisation does not fully account for anthropometric variables that differ across pitchers and leads to different conclusions in the magnitude of velocity's predictive effect on elbow valgus torque. Therefore, we recommend using regression model comparison to account for anthropometric variables in baseball pitching kinetic data.

Ground reaction forces in baseball pitching: temporal associations with pitch velocity among high-velocity pitchers.

How baseball pitchers interact with the ground is an important aspect of pitching technique and performance. Previous studies on ground reaction forces in baseball pitching have largely been limited to pitchers at the youth or adolescent level, with only a few studies examining higher velocity pitchers. Additionally, previous studies have limited their analyses to only peak kinetic values, neglecting any temporal importance of when these peak values occur. Therefore, our purpose was to provide normative ground reaction force values and examine the associations between pitch velocity and ground reaction forces in high-velocity pitchers. We retrospectively extracted pitch velocities as well as rear and lead leg ground reaction force data from internal databases for 105 high-velocity pitchers. We analysed the associations between the full ground reaction force time series and pitch velocity using statistical parametric mapping regression. Regression analysis revealed pitch velocity significantly predicted lead leg braking ground reaction force from approximately 27% to 35% of the period between front foot contact and ball release. These data reinforce the importance of effective braking forces for achieving maximal pitch velocities. Additionally, our observed peak ground reaction force values were considerably higher than those previously reported.

Preliminary Analysis of Closed Kinetic Chain Upper Extremity Stability Test Differences Between Healthy and Previously Injured/In-Pain Baseball Pitchers.

BACKGROUND: A comprehensive examination of the kinetic chain during an overhead athlete's upper extremity assessment, such as the closed kinetic chain upper extremity stability test (CKCUEST), may help clinicians identify potential upper extremity dysfunction. HYPOTHESIS: Body position observed on dominant and nondominant hand touch during a CKCUEST trial differs between players with previous injury/pain history compared with healthy counterparts. STUDY DESIGN: Descriptive laboratory study. LEVEL OF EVIDENCE: Level 5. METHODS: Seventeen baseball pitchers were recruited to participate (18.03 ± 2.01 years; 185.40 ± 6.57 cm; 83.92 ± 13.87 kg). A medical history questionnaire was used to separate participants into groups, either previous injury/pain or healthy. Kinematic and kinetic data were collected on the participants performing the CKCUEST with an electromagnetic tracking system. Kinematics were analyzed using a pair of 1-way multivariate analyses of variance (MANOVAs). RESULTS: The MANOVA for nondominant hand touch in the CKCUEST revealed a significant difference in lumbopelvic-hip complex (LPHC) kinematics between previously injured/pain group and healthy group (Λ = 0.37; F4,12 = 5.12; P = 0.01). CONCLUSIONS: The previously injured/pain group displayed less pelvic axial rotation and dominant hip abduction during the nondominant touch indicating more LPHC stability during the nondominant touch. In conclusion, differences were observed in LPHC kinematics during the CKCUEST nondominant touch between a healthy and previously injured/pain group perhaps due to the increased awareness provided through rehabilitative programs for the previously injured/pain group. CLINICAL RELEVANCE: Clinicians can use this information to help address kinetic chain movement efficiency within baseball pitchers. This study provides evidence of LPHC kinematic differences during the nondominant touch of baseball pitchers and may enhance the use of the CKCUEST as a return-to-play assessment.

Energy flow through the lower extremities in high school baseball pitching.

It is generally accepted that most of the energy transferred to the ball during a baseball pitch is generated in the trunk and lower extremities. Therefore, purpose of this study was to assess the energy flow through the lower extremities during a baseball pitch. It was hypothesised that the (stabilising) leading leg mainly transfers energy in a distal-to-proximal order as a kinetic chain while the (driving) trailing leg generates most energy, primarily at the hip. A joint power analysis was used to determine the rates of energy (power) transfer and generation in the ankles, knees, hips and lumbosacral joint (L5-S1) for 22 youth pitchers. Analyses showed that the leading leg mainly transfers energy upwards in a distal-to-proximal order just before stride foot contact. Furthermore, energy generation was higher in the trailing leg and primarily arose from the trailing hip. In conclusion, the legs contribute differently to the energy flow where the leading leg acts as an initial kinetic chain component and the trailing leg drives the pitch by generating energy. The actions of both legs are combined in the pelvis and passed on to the subsequent, more commonly discussed, open kinetic chain starting at L5-S1.

Pelvis and Trunk Energy Flow in Collegiate Softball Pitchers With and Without Upper Extremity Pain.

BACKGROUND: The softball pitch is a full-body motion, where efficient proximal to distal energy flow through the kinetic chain is said to reduce stress at the upper extremity. Although altered trunk kinematic parameters are associated with upper extremity pain in softball pitchers, further research is needed to determine whether differences exist in proximal energy flow between softball pitchers with and without pain. HYPOTHESIS/PURPOSE: To examine pelvis and trunk energy flow during the acceleration phase of the pitch in collegiate softball pitchers with and without upper extremity pain. It was hypothesized that those with upper extremity pain would have less energy flowing into the proximal ends of the pelvis and trunk as well as less energy flowing out of the distal ends of the pelvis and trunk during the acceleration phase when compared with pitchers who did not have upper extremity pain. STUDY DESIGN: Descriptive laboratory study. METHODS: A total of 54 female National Collegiate Athletic Association Division I softball pitchers (age, 20.2 ± 2.0 years; height, 173.5 ± 6.9 cm; weight, 78.5 ± 11.5 kg) were assigned to pain (n = 17) and pain-free (n = 38) groups. Participants pitched 3 maximal effort rise-balls for a strike, and the average of the 3 trials was used for analysis. Kinematic data were collected at 100 Hz using an electromagnetic tracking system. A segment power analysis was performed to quantify energy flow for the pelvis and trunk. The Mann-Whitney U test was used to compare pelvis and trunk energy flow during the acceleration phase of the pitch as well as pitch velocity between collegiate softball pitchers with and without upper extremity pain. RESULTS: No significant differences were found between pelvis and trunk energy flow during the acceleration phase or pitch velocity between collegiate softball pitchers with and without upper extremity pain (all P values >.057). CONCLUSION: Previous research determined that kinematic parameters differ between collegiate pitchers with and without upper extremity pain. However, the current study found no difference in pelvis and trunk energy flow or pitch velocity. Although altered kinematics in collegiate pitchers with upper extremity pain may serve as compensation patterns to maintain pitch velocity and proximal energy flow, future research is needed to confirm this postulation. CLINICAL RELEVANCE: The lack of energy flow differences between upper extremity pain groups suggests that pitchers may adapt their biomechanics to maintain trunk and pelvis energy flow patterns. Coaches, athletes, and clinicians should know that movement adaptations can allow for maintained performance levels but may result in the presence of pain that may manifest in other deleterious and injury-susceptible biomechanics.

Comparison of Pelvis and Trunk Kinematics Between Youth and Collegiate Windmill Softball Pitchers.

BACKGROUND: The windmill softball pitch is a dynamic sporting movement that places softball pitchers at high risk of injury. Unlike baseball, there is limited research into the mechanical differences between softball pitchers of varying skill levels. PURPOSE/HYPOTHESIS: The purpose of this study was to compare pelvis and trunk kinematics between youth and collegiate softball pitchers. It was hypothesized that there would be significant differences in pelvis and trunk kinematics between these 2 groups. STUDY DESIGN: Descriptive laboratory study. METHODS: The pelvic and trunk kinematics of 90 softball pitchers were collected during full-effort pitching using a 3-dimensional motion capture system. Participants were grouped based on their age at the time of data collection (35 youth [mean age, 11 ± 1 years]; 55 collegiate [mean age, 20 ± 2 years]). We compared between-group differences in pelvic posterior tilt, lateral tilt, axial rotation, and axial rotation velocity as well as trunk extension, lateral flexion, axial rotation, and axial rotation velocity during the pitching phase between start of pitch and ball release (BR) using 1-dimensional statistical parametric mapping. Statistical significance was determined using Holmes-Sidák stepdown correction-adjusted P values (P '). RESULTS: Compared with youth pitchers, collegiate pitchers exhibited a more posteriorly tilted pelvis from the moment of start of pitch until 94% of the way between start of pitch and BR (P ' = .002) and a more laterally flexed trunk toward the glove side from the moment of start of pitch until 71% of the way between start of pitch and BR (P ' = .010). CONCLUSION: Collegiate pitchers displayed a more posteriorly tilted pelvis and more laterally flexed trunk toward the glove side during the windmill pitching motion when compared with youth pitchers. CLINICAL RELEVANCE: These findings add to the growing body of softball research and help elucidate mechanical differences between youth and collegiate softball pitchers.

Hip Range of Motion and Strength and Energy Flow During Windmill Softball Pitching.

CONTEXT: Inadequate hip range of motion (ROM) and isometric strength (ISO) may interfere with energy flow through the kinetic chain and result in increased injury susceptibility. OBJECTIVE: To examine the relationship of hip ROM and ISO with energy flow through the trunk and pitching-arm segments during the windmill softball pitch in youth athletes. A subsequent purpose was to examine the relationship between energy flow and pitch speed. DESIGN: Descriptive laboratory study. SETTING: University research laboratory. PATIENTS OR OTHER PARTICIPANTS: A sample of 29 youth softball pitchers (age = 11.2 ± 1.3 years, height = 155.0 ± 10.4 cm, mass = 53.2 ± 12.6 kg). MAIN OUTCOME MEASURE(S): Bilateral hip internal-rotation and external-rotation (ER) ROM and ISO were measured. Net energy outflow and peak rates of energy outflow from the distal ends of the trunk, humerus, and forearm were calculated for the acceleration phase of the windmill softball pitch, and pitch speed was measured. RESULTS: Regression analysis revealed an effect of drive-hip ER ISO on the net energy flow out of the distal ends of the trunk (P = .045) and humerus (P = .002). Specifically, increased drive-hip ER ISO was associated with increased net energy outflow from the trunk to the humerus and from the humerus to the forearm. No significant effects of hip ROM or other hip ISO measures were observed. Additionally, pitchers who achieved higher peak rates of distal outflow tended to achieve higher pitch speeds. CONCLUSIONS: An association was present between drive-hip ER ISO and the net energy flow out of the distal ends of the trunk and humerus during the acceleration phase of the windmill softball pitch, emphasizing the importance of hip and lower body strength in executing the whole-body windmill pitch. Overall, energy-flow analysis is an interesting new way to analyze pitching mechanics and will aid in furthering our understanding of performance and injury risk in windmill softball pitching.

Increased Upper Arm Length and Loading Rate Identified as Potential Risk Factors for Injury in Youth Baseball Pitchers.

BACKGROUND: In the throwing elbow, increased elbow torque has been correlated with increased injury risk. Additional insight into the relationships between anthropometric factors and elbow joint loading is warranted. PURPOSE: To investigate the relationship among physical limb length characteristics, elbow kinetics, and elbow kinematics in youth baseball pitchers and to examine the relationship between elbow varus loading rate and elbow kinetics. DESIGN: Descriptive laboratory study. METHODS: A total of 27 male youth baseball pitchers participated (mean ± SD: age, 15.8 ± 2.7 years; height, 176.3 ± 13.0 cm; weight, 71.7 ± 16.4 kg). Upper arm (UA) and forearm (FA) lengths were measured using a moveable sensor to digitize bony landmarks. Kinematic data were collected at 240 Hz using an electromagnetic tracking system. Participants threw 3 fastballs to a catcher at a regulation distance (60 ft 6 in), and the fastest velocity trial was used for analysis. Linear regression was used to determine the relationship among limb length characteristics, elbow kinetics, and elbow kinematics after accounting for the effects of body weight and height. RESULTS: Pitchers with longer UA length experienced increased maximum elbow varus torque (P = .005) and maximum net elbow force (P = .001). Pitchers with an increased forearm to UA ratio had decreased elbow compression force (P < .001) and exhibited a more flexed elbow at foot contact (P = .001). Pitchers with greater maximum loading rates experienced greater elbow varus torque (P = .002). CONCLUSION: In youth baseball pitchers, longer UA length and greater loading rate increase varus torque about the elbow during a fastball pitch. CLINICAL RELEVANCE: Longer UA length and greater loading rate may place pitchers at risk of injury because of their relationship with kinetic values.

Energy generation, absorption, and transfer at the shoulder and elbow in youth baseball pitchers.

Performance during the baseball pitch is dependent on the flow of mechanical energy through the kinetic chain. Little is known about energy flow during the pitching motion and it is not known whether patterns of energy flow are related to pitching performance and injury risk. Therefore, the purpose of this study was to quantify energy generation, absorption, and transfer across the shoulder and elbow during the baseball pitch and explore the associations between these energetic measures, pitch speed, and traditional measures of upper extremity joint loading. The kinematics of 40 youth baseball pitchers were measured in a controlled laboratory setting. Energy flow between the thorax, humerus, and forearm was calculated using a segmental power analysis. Regression analyses revealed that pitch speed was best predicted by arm cocking phase shoulder energy transfer to the humerus and peak elbow valgus torque was best predicted by arm acceleration-phase elbow energy transfer to the forearm. Additionally, energy transfer across the shoulder and elbow generally exhibited the strongest correlations to pitch speed and upper extremity joint loads. These data reinforce the importance of energy transfer through the kinetic chain for producing high pitch speeds and provide descriptive data for energy flow during baseball pitching not previously found in the literature.

Effects of Hip Range of Motion and Isometric Strength on Energy Flow during Windmill Softball Pitching.

CONTEXT: Inadequate hip range of motion (ROM) and isometric strength (ISO) may interfere with energy flow through the kinetic chain and result in increased injury susceptibility. OBJECTIVE: To examine the relationship of hip ROM and ISO with energy flow through the trunk and pitching arm segments during the windmill softball pitch in youth athletes. A subsequent purpose was to examine the relationship between energy flow and pitch speed. DESIGN: Descriptive laboratory study. SETTING: University research laboratory. PARTICIPANTS: A sample of 29 youth softball pitchers (11.2±1.3 yrs.; 155.0±10.4 cm; 53.2±12.6 kg). MAIN OUTCOME MEASURE(S): Bilateral hip internal rotation (IR) and external rotation (ER) ROM and ISO were measured. Net energy outflow and peak rates of energy outflow from the distal ends of the trunk, humerus, and forearm were calculated for the acceleration phase of the windmill softball pitch, and pitch speed was measured. RESULTS: Regression analysis revealed a significant effect of drive hip ER ISO on the net energy flow out of the distal ends of the trunk (p=0.045) and humerus (p=0.002). Specifically, increased drive hip ER ISO was associated with increased net energy outflow from the trunk to the humerus and from the humerus to the forearm. No significant effects of hip ROM or other hip ISO measures were observed. Additionally, pitchers who achieved higher peak rates of distal outflow tended to also achieve higher pitch speeds. CONCLUSIONS: There is an association between drive hip ER ISO and the net energy flow out of the distal ends of the trunk and humerus during the acceleration phase of the windmill softball pitch, emphasizing the importance of hip and lower body strength in the execution of the whole-body windmill pitch. Overall, energy flow analysis is an interesting new way to analyze pitching mechanics and will aid in further understanding of performance and injury risk in windmill softball pitching.

Segment power analysis of collegiate softball hitting.

The primary aim of this investigation was to describe the energy flow through the kinetic chain during softball hitting using a segmental power analysis. Twenty-three NCAA Division I collegiate softball athletes (20.4 ± 1.7 yr; 166.7 ± 22.0 cm; 74.9 ± 15.9 kg) performed three maximum effort swings off a stationary tee placed in the middle of the strike zone. Pelvis, trunk, humerus, forearm and hand segment powers were integrated across four phases of the softball swing (load, stride, acceleration, and follow-through). The load and stride phases had low segment energy inflow and outflow values as well as net segment energy flow for all body segments compared to subsequent phases of the swing. The acceleration phase showed large trunk inflow values relative to the pelvis. There was also descriptively larger front compared to back-side upper extremity inflow. Finally, the follow-through phase showed primarily energy outflow for the upper extremity segments likely attributed to slowing down rotation.