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Abstract

Background:

Relationships between the back leg's lumbopelvic control and throwing arm kinetics have been established in throwing athletes. However, little literature has established normative values for in-pitch hip flexion parameters as well as the role that hip flexion-extension excursion may play in the generation of throwing arm kinetics and ball velocity.

Purpose:

(1) To establish normative values for lead and back hip flexion for high school (HS) pitchers and (2) to investigate the relationship of lead and back hip flexion-extension excursion with throwing arm kinetics, full body kinematics, and ball velocity.

Study Design:

Descriptive laboratory study.

Methods:

A total of 56 HS pitchers, who were instructed to throw 8 to 12 fastball pitches, were evaluated with 3-dimensional motion capture. The mean normative values of lead and back hip flexion-extension excursion were calculated and compared with an internal database of professional pitchers for comparison. HS pitchers were then divided into quartiles based on “high” and “low” lead and back hip flexion-extension excursion. Multiple regression models examined the association of lead and back hip excursion, controlling for anthropometric parameters, with ball velocity and throwing arm kinetics.

Results:

HS pitchers had decreased lead hip (43°± 14° vs 48°± 14.6°, respectively; p = .038) and back hip (50°± 18° vs 56°± 15°, respectively; p = .009) flexion excursion compared with professional pitchers. Pitchers with low lead hip and low back hip excursion also had significantly less shoulder internal rotation torque (3.5%BW × BH vs 4.5%BW × BH and 4.4%BW × BH, respectively; P_max = .03), shoulder anterior force (30.4%BW vs 36.3%BW and 35.8%BW, respectively; P_max = .03), elbow varus torque (3.3%BW × BH vs 4.3%BW × BH and 4.2%BW × BH, respectively; P_max = .02), and elbow medial force (27.1%BW vs 35.5%BW and 34.1%BW, respectively; P_max = .03) compared with pitchers with high lead hip and high back hip excursion as well as pitchers with high lead hip and low back hip excursion. When controlling for anthropometric parameters, lead and back hip excursion were not strongly predictive for ball velocity (P > .05). Only back hip excursion was moderately predictive for shoulder anterior force (P = .04; B = 0.118 [confidence interval 0.006-0.230]; β = 0.272).

Conclusion:

HS pitchers had less lead and back hip flexion-extension excursion compared with professional pitchers. Lead and back hip flexion-extension excursion likely play small roles in ball velocity for HS pitchers; however, increased back hip flexion-extension excursion may be a risk factor for higher shoulder anterior force.

Clinical Relevance:

Establishing normative values for hip flexion excursion in HS pitchers provides clinicians, coaches, and strength and conditioning professionals with important benchmarks for assessing lower body mechanics during pitching. The identification of reduced lead and back hip flexion excursion in HS pitchers compared to professionals highlights a potential developmental gap that may influence throwing arm kinetics. Although hip flexion excursion appears to have minimal impact on ball velocity, increased back hip excursion was associated with higher shoulder anterior forces, suggesting a possible risk factor for shoulder load. These findings can inform targeted training interventions to improve lower body mechanics, reduce upper extremity loading, and ultimately contribute to safer pitching practices for developing pitchers.

Keywords

extension kinematics kinetics mechanics fastball pitching

The function of lower extremity kinematics as a component of the kinetic chain for baseball pitchers has been long been a source of examination for researchers.^{1,11,12,15,20,21} In particular, the role that the hip, both lead and back, plays is of particular importance as a means to provide a stable base to rotate the trunk and to continue the kinetic chain, respectively.¹⁵

Previous literature has focused on active and passive hip range of motion (ROM) in baseball pitchers as a metric to assess in-pitch kinematic and kinetic parameters. Albiero et al¹ noted that in adolescent pitchers, back hip extension ROM was positively correlated with stride length, while lead hip abduction ROM was positively correlated with normalized elbow varus torque.² In fact, compensatory kinematic movements of the shoulder with changes in passive hip rotational motion have been noted when evaluating youth pitchers; in particular, shoulder external rotation of the throwing arm was correlated with the degree of both lead and back hip internal rotation.⁷

Still, to date, little literature has established normative values for in-pitch hip flexion parameters among playing levels as well as the role that hip flexion-extension excursion may play in the generation of throwing arm kinetics and ball velocity. Therefore, the purpose of this study was (1) to establish normative values for lead and back hip flexion for high school (HS) pitchers in comparison to an internal database of professional pitchers and (2) to discern a plausible relationship of lead and back hip flexion-extension excursion with throwing arm kinetics, full body kinematics, and ball velocity. We hypothesized that HS pitchers with decreased lead and back hip excursion would experience increased throwing arm kinetics as a compensatory mechanism of force generation in the kinetic chain.

Methods

A total of 56 HS pitchers and 288 professional pitchers were included in this study. Inclusion requirements for professional pitchers were as follows: (1) at the time of testing, pitchers were on the Major League or Minor League (Low A, High A, AA, and AAA) roster; (2) pitchers had no record of a serious injury (requiring >2 weeks of rest or rehabilitation) in the past 6 months; and (3) pitchers were cleared by team clinicians to participate in baseball activities. Inclusion requirements for HS pitchers were as follows: (1) at the time of testing, pitchers were on an HS or club team; (2) pitchers had no record of a serious injury (requiring >2 weeks of rest or rehabilitation) in the past 6 months; and (3) pitchers were cleared to participate in baseball activities by their physician. Motus Global (Rockville Centre, NY) deidentified all data before the inclusion of participants, thus qualifying for exempt institutional review board approval under federal guidelines.

Pitching evaluations were conducted as previously described.^4,10 Pitchers reported to the test site, and a privacy waiver was administered with consent provided. For underage pitchers, parents provided consent, and the pitchers provided assent. Demographic data were reported by the pitcher and included age, preferred throwing arm, years of play, and history of injuries. Researchers measured and recorded the pitchers’ height with a standard tape measure and weight using a medical scale. The pitcher was given unlimited time to warm up with his preferred routine of pitching at maximum effort (ie, arm bands, stretching, PlyoCare balls, long toss). Once the pitcher indicated that he was ready to pitch, 46 reflective markers were placed on anatomic landmarks.¹⁰ The 8-camera Raptor-E motion analysis system (Motion Analysis) was used to record the markers at 480 Hz. Before pitching, data from a single static calibration were collected with the pitcher standing in the capture volume and the legs hip-width apart, the shoulders abducted at 90°, and the elbows flexed at 90°. The static test was conducted to align the pitcher with the laboratory coordinate system and to define the local coordinate systems. The global coordinate system was established based on the International Society of Biomechanics standards: Y was vertically upward, X was perpendicular to Y (positive to home plate), and Z was the cross-product of X and Y.

Pitchers were instructed to pitch 8 to 12 fastballs from a standard dirt mound with game-like effort to a catcher behind home plate at a regulation distance (18.4 m). Pitchers pitched at their own set rate and were given the option to pitch from the stretch or the windup.^6,17 Ball velocity was recorded using a radar gun (Stalker Sport) located behind the pitcher.

All data processing for full body kinematics and throwing arm kinetics was performed with MATLAB scripts (MathWorks) as previously described.^4,10 Data from the markers were filtered by a low-pass filter (fourth-order, zero-lag Butterworth filter; 13.4-Hz cutoff frequency).⁹ There were 7 time points of the pitch used in this study (Figure 1): maximum knee height (MKH), separation of hands (SH), elbow extension (EE), foot contact (FC), maximum shoulder external rotation (MER), ball release (BR), and maximum shoulder internal rotation (MIR). MKH was identified as the frame in which the lead knee reached the maximum value in the Y direction. SH was denoted as the frame of maximum acceleration of the combined vectors between the 2 wrist centers. EE was defined as the time point at which the elbow reached its maximum extension before FC. FC was defined as the first frame in which the lead toe or heel reached the minimum in the Y axis. MER was established as the frame in which the throwing arm achieved maximum external rotation with respect to the trunk. BR was determined to be an instant of 0.01 seconds after the wrist passed the elbow in the forward direction.^4,9 MIR was identified as the frame in which the throwing arm reached maximum internal rotation after BR. Pitch time parameters were defined as a percentage of the pitch, starting at FC (0%) to BR (100%). Hip rotation was calculated as the angle between the pelvis and femur in the transverse plane, and a negative value indicated internal rotation and positive was external rotation. Hip flexion was calculated as the angle between the pelvis and femur in the sagittal plane, where a positive value was considered flexion and negative was extension.

Figure 1.

A visual depiction of the time points throughout the pitch.

The joint reaction force exerted on the shoulder can be divided into vectors of anterior, proximal (compressive), and superior forces in which the anterior, proximal, and superior forces on the shoulder reflect positive values and posterior, distal (distractive), and inferior forces represent negative values.¹⁸ Peak kinetic forces were calculated and subsequently normalized by the pitcher's weight (% body weight [BW]), while peak kinetic torques were normalized by the pitcher's weight and height (% BW × body height [BH]).^4,10

Statistical Analysis

As the number of pitches thrown per pitcher was not uniform, the mean of all independent variables and the dependent variable was calculated per pitcher. Both lead and back hip flexion were plotted at the established pitching time points, with an independent t test conducted at each time point for lead and back hip flexion between HS and professional pitchers. The maximum and minimum hip flexion for both the lead and back hip occurred at EE and MER. Therefore, the difference in hip flexion at these time points was defined as “hip excursion.” High hip excursion defined pitchers with a large difference in hip flexion values between EE and MER. Low hip excursion defined pitchers with a small difference in hip flexion values between EE and MER. The mean lead and back hip flexion values were then placed in a scatterplot to divide HS pitchers into quartiles based on high and low lead and back hip flexion using the following nomenclature:

Q1 = high lead hip, high back hip;

Q2 = low lead hip, high back hip;

Q3 = high lead hip, low back hip; and

Q4 = low lead hip, low back hip.

Quartiles were subsequently compared using analysis of variance for specific anthropometric, kinematic, and kinetic variables of interest, as well as ball velocity, with the post hoc Tukey honestly significant difference test for specific subgroup comparisons. Lastly, multiple regression models for kinetic parameters of interest or those that derived significance from initial analysis of variance were created, controlling for anthropometric parameters, including age, weight, and leg length, with lead and back hip flexion-extension excursion. Similar models were created for ball velocity. Regression coefficients were standardized by multiplying the coefficient for the independent variable by the ratio of the standard deviation of the predictor variable and the standard deviation outcome variable, as noted:

β_{i} = b_{i} * S_{Xi} / S_{Y} .

All statistical analyses were performed using R (R Core Team). Alpha was set to .05 for all tests.

Results

HS pitchers demonstrated increased lead hip flexion at SH (58°± 16° vs 51°± 19°, respectively; P > .001), EE (45°± 13° vs 40°± 14°, respectively; P = .015), and MIR (82°± 10° vs 78°± 12.4°, respectively; P > .001) compared with professional pitchers (Figure 2). HS pitchers demonstrated less back hip flexion at SH (40°± 16° vs 35°± 17°, respectively; P = .018), and greater back flexion at MER (–6°± 8° vs −9°± 9°, respectively; P = .018), BR (3°± 9° vs −1°± 10°, respectively; P > .001), and MIR (11°± 10° vs 6°± 11°, respectively; P > .001) compared with professional pitchers. HS pitchers had less lead hip (43°± 14.3° vs 48°± 15°, respectively; P = .038) and back hip (50°± 18° vs 56°± 15°, respectively; P = .009) flexion excursion compared with professional pitchers. HS pitchers were younger, were lighter, had shorter leg lengths, and had a slower ball velocity compared with professional pitchers (P < .05).

Figure 2.

Comparison of high school (HS) and professional (PRO) baseball pitchers for (A) lead hip flexion and (B) back hip flexion at different pitch time points. BR, ball release; EE, elbow extension; FC, foot contact; MER, maximum shoulder external rotation; MIR, maximum shoulder internal rotation; MKH, maximum knee height; SH, separation of hands. *Significance at P < .05.

The quartiles for high and low lead and back hip flexion-extension excursion subgroups are shown in Figure 3. Quartiles were compared for anthropometric, kinematic, and kinetic differences as shown in Table 1. No differences were noted in anthropometric parameters or ball velocity between subgroups (P > .05). HS pitchers in the Q4 subgroup (low lead, low back) had significantly less lead knee flexion at FC compared with pitchers in the Q1 subgroup (high lead, high back) (absolute difference = 10°; P = .03) and demonstrated the slowest maximum trunk rotation velocity compared with all the other subgroups. HS pitchers in the Q4 subgroup (low lead, low back) had significantly less shoulder internal rotation torque (P_max = .03), shoulder anterior force (P_max = .03), elbow varus torque (P_max = .02), and elbow medial force (P_max = .03) compared with pitchers in the Q1 subgroup (high lead, high back) and Q3 subgroup (high lead, low back).

Figure 3.

Scatterplot for mean lead and back hip flexion-extension excurion.

Table 1

Quartile Comparisons of Anthropometric, Kinematic, and Kinetic Parameters for High School Pitchers^a

	Q1 (High Lead, High Back; n = 18)	Q2 (Low Lead, High Back; n = 17)	Q3 (High Lead, Low Back; n = 14)	Q4 (Low Lead, Low Back; n = 7)	P
Handedness, R/L, n	15/3	13/4	10/4	5/2
Age, y	16.5 ± 1.4	16.1 ± 1.3	16.7 ± 1.9	16.0 ± 0.7
Height, cm	178.3 ± 10.1	183.4 ± 4.5	177.3 ± 7.5	181.4 ± 7.1
Weight, kg	74.6 ± 7.7	77.1 ± 11.1	73.7 ± 16.8	70.0 ± 7.6
Leg length, cm	90.3 ± 8.5	90.4 ± 4.1	87.5 ± 7.2	94.3 ± 3.3
Ball velocity, m/s	31.8 ± 2.7	31.1 ± 2.5	31.2 ± 3.7	30.2 ± 2.6
Stride length at FC, %BH	77.7 ± 4.3	76.3 ± 4.5	75.6 ± 4.0	75.0 ± 5.4
Stride width at FC, cm	12.1 ± 5.7	24.3 ± 6.7	18.4 ± 6.1	16.5 ± 8.1	^b
Shoulder abduction at FC, deg	88 ± 7	91 ± 13	84 ± 16	96 ± 19
Lead knee flexion at FC, deg	47 ± 5	46 ± 7	44 ± 9	37 ± 9	^{c , d}
Pelvis rotation at FC, deg	61 ± 12	64 ± 10	60 ± 11	63 ± 13
Trunk rotation at FC, deg	39 ± 12	33 ± 7	40 ± 12	37 ± 10
Lead hip internal rotation at FC, deg	−10 ± 14	−8 ± 14	−17 ± 15	−21 ± 17
Back hip internal rotation at FC, deg	7 ± 13	5 ± 14	7 ± 17	2 ± 12
Shoulder external rotation at MER, deg	160 ± 15	160 ± 8	164 ± 8	166 ± 8
Shoulder abduction at MER, deg	92 ± 9	96 ± 7	90 ± 8	98 ± 14	^e
Shoulder horizontal adduction at MER, deg	11 ± 11	13 ± 5	6 ± 9	15 ± 12	^e
Lead hip internal rotation at MER, deg	1 ± 10	4 ± 12	−5 ± 10	2 ± 15	^e
Back hip internal rotation at MER, deg	−12 ± 9	−20 ± 8	−8 ± 11	−20 ± 10	^{e , f , g}
Elbow flexion at BR, deg	31 ± 7	29 ± 6	28 ± 6	37 ± 12
Lead knee flexion at BR, deg	39 ± 9	41 ± 12	44 ± 14	35 ± 13
Arm slot at BR, deg	52 ± 12	51 ± 11	47 ± 11	56 ± 11
Maximum trunk rotation, deg	42 ± 11	36.1 ± 7.2	47 ± 12	40 ± 10	^e
Maximum trunk flexion, deg	45 ± 13	43.4 ± 7.3	44 ± 6	36 ± 11
Maximum lead knee extension velocity, deg/s	321 ± 135	285.3 ± 116.5	267 ± 84	240 ± 138
Maximum pelvis rotation, deg	642 ± 85	646 ± 97	623 ± 76	664 ± 89
Timing of maximum pelvis rotation velocity, % time	44 ± 8	40 ± 8	46 ± 11	46 ± 8
Maximum trunk rotation velocity, deg/s	664 ± 164	509 ± 138	702 ± 303	488 ± 80	^{c , e , f , g}
Timing of maximum trunk rotation velocity, % time	59 ± 8	55 ± 12	57 ± 7	58 ± 9
Maximum trunk flexion velocity, deg/s	573 ± 115	535 ± 107	618 ± 126	533 ± 122
Timing of maximum trunk flexion velocity, % time	88 ± 9	86 ± 10	83 ± 5	80 ± 5	^c
Shoulder internal rotation torque, %BW×BH	4.5 ± 0.8	4.3 ± 0.5	4.4 ± 0.5	3.5 ± 0.8	^c,d,g
Shoulder superior force, %BW	20.8 ± 6.8	21.4 ± 6.1	18.3 ± 9.8	189 ± 11.2
Shoulder anterior force, %BW	36.3 ± 7.0	38.1 ± 5.2	35.8 ± 6.5	30.4 ± 3.9	^{c , d , g}
Elbow varus torque, %BW×BH	4.3 ± 1	3.9 ± 1.2	4.2 ± 0.5	3 ± 0.7	^{c , g}
Elbow medial force, %BW	35.5 ± 7.3	31.3 ± 11.2	34.1 ± 6.6	27.1 ± 5.7	^{c , g}
Elbow anterior force, %BW	33.4 ± 7.3	30.8 ± 13.2	32.2 ± 5.9	31.1 ± 4.5
Elbow flexion torque, %BW × BH	3.2 ± 0.6	3.0 ± 1.1	3.1 ± 0.6	2.8 ± 0.6
Shoulder distractive force, %BW	93.2 ± 13.7	87.4 ± 13.1	89.2 ± 16.2	82.9 ± 16.4
Elbow distractive force, %BW	87.0 ± 14.2	82.9 ± 15.7	83.9 ± 16.5	81.0 ± 15.7	^{e , g}

Data are shown as mean ± SD unless otherwise indicated. Negative hip flexion is considered hip extension. BH, body height; BR, ball release; BW, body weight; FC, foot contact; L, left; MER, maximum shoulder external rotation; R, right. Significant differences (p < 0.05) between:

Q1 and Q3.

Q1 and Q4.

Q2 and Q4.

Q2 and Q3.

Q1 and Q2.

Q3 and Q4.

When controlling for anthropometric parameters (age, weight, leg length), lead and back hip excursion were not significant in the relationship to ball velocity for HS pitchers (P > .05). Of the kinetic parameters, only back hip excursion was moderately predictive for shoulder anterior force (P = .04; B = 0.118 [CI 0.006-0.230]; β = 0.272).

Discussion

Professional and HS pitchers differed in how they used their back and lead hips throughout the pitch. HS pitchers demonstrated greater lead hip flexion and less back hip flexion at early portions of the pitch compared with professional pitchers. When delineating pitchers by the degree of lead and back hip flexion-extension excursion throughout the pitch, HS pitchers with low lead and low back hip excursion demonstrated the slowest pitch velocities with the lowest throwing arm kinetics, although these ball velocity differences were not extrapolated to the regression models. Lastly, increased back hip flexion-extension excursion was modestly correlated with normalized shoulder anterior force.

Comparisons of in-pitch or dynamic hip ROM values in the literature have shown agreeable results when considering playing levels. Milewski et al¹³ evaluated adolescent pitchers (mean age, 12 years) and noted that the lead hip began at 64° of flexion at FC and continued to flex 22° by the time of MIR. This is in agreement with the HS pitchers in the current study; however, it should be noted that the hip excursion values reported in Milewski et al’s¹³ study were from FC to MIR and therefore are not directly applicable, as our study defined hip excursion starting at EE. Pryhoda and Sabick¹⁵ evaluated youth pitchers who demonstrated similar back hip flexion at MKH; however, while our cohort of HS and professional pitchers extended the back hip from FC to MER, the youth pitchers approached neutral flexion but not extension at later portions of the pitch, suggesting a stark difference in pitching mechanics between youth pitchers and older pitching cohorts. Whether these differences are attributable to skill, maturity, age, or physiological differences as children mature is unclear; however, it is important that the extrapolation of results from a study conducted at one playing level is likely inappropriate to apply to others.

Our study's results suggest differences in in-pitch hip flexion parameters between HS and professional pitchers. HS pitchers had decreased lead and back hip flexion-extension excursion compared with professional pitchers. This could be caused by the ability of a professional pitcher to have the strength and balance to move the lead hip a greater amount as he brings his lead knee into MKH and then stride down the mound. HS pitchers demonstrated increased lead hip flexion and decreased back hip flexion at early portions of the pitch compared with professional pitchers. Given that the lead leg typically reaches peak braking force with a predominant vertical ground-reactive component at late portions of the pitch,¹⁶ it may suggest that professional pitchers have developed an improved mechanism by which to push off the lead leg. Dowling et al⁵ noted that professional pitchers with the fastest ball velocity had greater lead knee extension, suggesting that flexing the knee after landing can result in energy dissipation. This similarly can apply to hip flexion requiring more extension at late portions of the pitch to create a stable base for subsequent rotational motion of the pelvis to lever.

Contrary to our hypothesis, increased back hip flexion-extension excursion was found to be modestly correlated with normalized shoulder anterior force in HS pitchers. Previous literature in youth pitchers has suggested compensatory movements of the shoulder with changes in passive hip rotational motion.⁷ Considering the role that the back leg plays in propelling the center of mass forward toward home plate, there may be negative upper extremity compensatory movements with excessive excursion of the back hip. It should be noted that no statistically significant correlations have been found between dynamic hip rotational ROM and passive hip rotational ROM in youth analyses, suggesting that much of the previous literature correlating active and passive hip ROM parameters with outcomes of interest may not necessarily apply to in-pitch hip excursion parameters.⁷

This study has clinical applicability. Establishing critical kinematic differences between HS and professional pitchers lends support for training programs to take into account these significant differences when developing appropriate rehabilitation, training, and pitch restrictions for cohorts with different levels of pitching. Even more, our results suggest that increased back hip flexion-extension excursion may be a risk factor for higher shoulder anterior force in HS pitchers. Shoulder anterior force has been reported to be a source of anterior shoulder pain and injuries in pitchers, implicated in a variety of pathological conditions including internal impingement of the shoulder, glenohumeral internal rotation deficits, and anterior capsular laxity.^14,16,18 Minimizing these excursion parameters for HS pitchers may be beneficial in the prevention of these common abnormalities encountered by pitching cohorts. Nevertheless, these recommendations should be taken lightly, given the use of throwing arm kinetics as surrogates for definitive joint loading.

Limitations

This study must be considered with limitations. Each pitcher was asked to throw with game-like intensity but it is possible their effort may not have reflected game-day effort. Additionally, pitchers only threw 8 to 12 fastballs, which may not fully reflect game pitch counts. It is possible that hip mechanics change as players increase throw counts with continued exertion; fatigue has been shown to influence performance outcomes.^2,3,8,19 Because pitching data were only obtained for fastballs, the application of these findings to other pitch styles is unclear and warrants additional exploration. Lastly, hip flexion-extension excursion only encompasses 1 parameter of dynamic hip motion, which also consists of motion in the rotational plane as well as about an abduction/adduction axis. The role that the hip may play with consideration of these additional planes of motion is not elucidated in the current study and likely warrants further investigation.

Conclusion

To date, no study, to our knowledge, has established and compared normative values for in-pitch hip flexion parameters among different playing levels or has explored the role that hip flexion-extension excursion may play in the generation of throwing arm kinetics and ball velocity. These results are important in establishing baseline kinematic normative values while also demonstrating the unique differences in pitching kinematics between playing levels. Lead and back hip flexion likely play small roles in ball speed for HS pitchers; however, increased back hip flexion-extension excursion may be a risk factor for increased shoulder anterior force. Focused training on lower extremity kinematics, strength, and lumbopelvic control in HS pitchers may influence throwing arm kinetics with potential injury risk implications.

Footnotes

Final revision submitted December 25, 2024; accepted January 3, 2025.

One or more of the authors has declared the following potential conflict of interest or source of funding: S.B. has received consulting fees from Smith & Nephew and support for education from Arthrex. E.P.S. has received hospitality payments from Arthrex and Smith & Nephew and support for education from Arthrex, Gotham Surgical, and Medwest Associates. S.J.N. has received royalties or licensing fees, support for education, and consulting fees from Arthrex. J.S.D. has received royalties from Arthrex and support for education from Gotham Surgical. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Ethical approval for this study was waived by Hospital for Special Surgery (No. 2020-1957).

ORCID iD

Brittany Dowling

Kyle Kunze

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Lead and Back Hip Flexion-Extension Excursion: A Biomechanical Analysis in High School Baseball Pitchers

Abstract

Background:

Purpose:

Study Design:

Methods:

Results:

Conclusion:

Clinical Relevance:

Keywords

Methods

Statistical Analysis

Results

Discussion

Limitations

Conclusion

Footnotes

ORCID iD

References