The purpose of this study was to quantify biomechanical parameters employing two-dimensional (2-D) and three-dimensional (3-D) analyses while performing the squat with varying stance widths.Two 60-Hz cameras recorded 39 lifters during a national powerlifting championship. Stance width was normalized by shoulder width (SW), and three stance groups were defined: 1) narrow stance squat (NS), 107 +/- 10% SW; 2) medium stance squat (MS), 142 +/- 12% SW; and 3) wide stance squat (WS), 169 +/- 12% SW.Most biomechanical differences among the three stance groups and between 2-D and 3-D analyses occurred between the NS and WS. Compared with the NS at 45 degrees and 90 degrees knee flexion angle (KF), the hips flexed 6-11 degrees more and the thighs were 7-12 degrees more horizontal during the MS and WS. Compared with the NS at 90 degrees and maximum KF, the shanks were 5-9 degrees more vertical and the feet were turned out 6 degrees more during the WS. No significant differences occurred in trunk positions. Hip and thigh angles were 3-13 degrees less in 2-D compared with 3-D analyses. Ankle plantar flexor (10-51 N.m), knee extensor (359-573 N.m), and hip extensor (275-577 N.m) net muscle moments were generated for the NS, whereas ankle dorsiflexor (34-284 N.m), knee extensor (447-756 N.m), and hip extensor (382-628 N.m) net muscle moments were generated for the MS and WS. Significant differences in ankle and knee moment arms between 2-D and 3-D analyses were 7-9 cm during the NS, 12-14 cm during the MS, and 16-18 cm during the WS.Ankle plantar flexor net muscle moments were generated during the NS, ankle dorsiflexor net muscle moments were produced during the MS and WS, and knee and hip moments were greater during the WS compared with the NS. A 3-D biomechanical analysis of the squat is more accurate than a 2-D biomechanical analysis, especially during the WS.
Background The curveball has been anecdotally considered as a dangerous pitch among youth pitchers, especially for their ulnar collateral ligaments. No biomechanical studies have been conducted among youth pitchers comparing different types of pitches. Hypothesis The kinetics of the baseball throw varies significantly between the fastball, curveball, and change-up for youth pitchers. Kinematic and temporal differences are also expected. Study Design Controlled laboratory study. Methods Twenty-nine youth baseball pitchers (age, 12.5 ± 1.7 years) pitched 5 fastballs, 5 curveballs, and 5 change-ups with maximum effort in an indoor laboratory setting. Data were collected with a 3-dimensional motion analysis system. Kinetic, kinematic, and temporal parameters were compared among the 3 pitches. Results For elbow varus torque, shoulder internal rotation torque, elbow proximal force, and shoulder proximal force, the fastball produced the greatest values, followed by the curveball and then the change-up. The fastball also produced the greatest elbow flexion torque. Shoulder horizontal adduction torque and shoulder adduction torque were the least for the change-up. Several differences in body segment position, velocity, and timing were also found. Conclusions In general, elbow and shoulder loads were the greatest in the fastball and least in the change-up. Kinematic and temporal differences were also found among the 3 pitch types. Clinical Relevance The curveball may not be more potentially harmful than the fastball for youth pitchers. This finding is consistent with recent epidemiologic research indicating that amount of pitching is a stronger risk factor than type of pitches thrown.
Ulnar collateral ligament (UCL) surgery continues to demonstrate excellent clinical outcomes and a high return-to-play (RTP) rate with a low complication rate. Recent studies have demonstrated similar clinical outcomes for baseball players who have undergone either UCL reconstruction or UCL repair. In comparison, few studies have assessed the clinical outcomes of UCL surgery for nonthrowing athletes.The primary objective of this study is to provide clinical outcomes of UCL surgery performed in nonthrowing athletes at a single institution with a minimum 2-year follow-up. Our hypothesis was that these patients would have similar clinical outcomes, complication rates, and RTP rates when compared with throwing athletes.Case series; Level of evidence, 4.From our longitudinal elbow registry, 40 nonthrowing athletes were identified who underwent UCL surgery (repair or reconstruction) between 2011 and 2019. Participant characteristics were recorded: age, sex, laterality, arm dominance, sport, level of competition, and type of surgery (UCL repair or reconstruction). Outcomes included RTP rate and average time, American Shoulder and Elbow Surgeons (ASES) scores, and complications.From the 40 patients eligible for inclusion in this study with a minimum 2-year follow-up, 37 (93%) were successfully contacted: 16 male (43%) and 21 female (57%). Mean ± standard deviation age at the time of surgery was 18.0 ± 3.7 years. From the 37 technical procedures, 28 (76%) were UCL repairs and 9 (24%) were UCL reconstructions. For these patients, 15 (41%) had partial tears, 20 (54%) had complete tears, 1 (3%) had a medial epicondyle avulsion, and 1 (3%) had an unspecified pathology. Sports included football (n = 11), gymnastics (11), cheerleading (7), wrestling (4), volleyball (2), basketball (1), and acrobatics (1). Quarterbacks were excluded from the football patients, as quarterbacks are throwing athletes. Level of competition included high school (n = 26), college (8), professional (2), and youth sports (1). The RTP rate was 93% (26/28) at a mean 7.4 months for UCL repair and 100% (9/9) at a mean 10.0 months for UCL reconstruction. Mean ASES scores were 94.4 and 98.7 for UCL repair and reconstruction, respectively. Complications were low, with 2 patients in the UCL repair group requiring ulnar nerve transposition for ulnar nerve paresthesia.In nonthrowing athletes, patients undergoing UCL repair and UCL reconstruction show favorable outcomes at minimum 2-year follow-up. RTP and clinical outcomes are consistent with previous studies in baseball players as well as a parallel ongoing study conducted on non-baseball throwing athletes.
The purpose of this study was to establish and compare kinematic data among four groups of collegiate pitchers who threw the fastball (FA), change-up (CH), curveball (CU), and slider (SL). Twenty-six kinematic parameters at lead foot contact, during the arm-cocking and arm acceleration phases, and at ball release were measured for 16 collegiate baseball pitchers. Approximately 60% of these parameters showed significant differences among the four pitch variations. The greatest number of differences (14 of 26) occurred between the FA and CH groups, while the fewest differences (2 of 26) occurred between the FA and SL groups. The CH group had the smallest knee and elbow flexion at lead foot contact and the greatest knee and elbow flexion at ball release. During the arm-cocking and arm acceleration phases, peak shoulder, elbow, and trunk angular velocities were generally greatest in the FA and SL groups and smallest in the CH group. At ball release the CH group had the most upright trunk and the greatest horizontal shoulder adduction, while the CU group had the most lateral trunk tilt. Understanding kinematic differences can help a pitcher select and learn different pitches and can help a batter learn how to identify different pitches.
Summary: The throwing motion is a complex movement pattern that requires flexibility, muscular strength, coordination, synchronicity of muscular firing, and neuromuscular efficiency. During the act of throwing, excessively high stresses are generated at the shoulder joint because of the unnatural movements frequently performed by the throwing. The thrower's shoulder must be flexible enough to allow the excessive external rotation required to throw a baseball. The overhead throwing motion places tremendous demands on the shoulder joint complex musculature to produce functional stability. The surrounding musculature must be strong enough to assist in arm acceleration but must exhibit neuromuscular efficiency to produce dynamic functional stability. During the act of pitching, the angular velocity at the shoulder joint exceeds 7,000° per second and has been referred to as the fastest human movement. Tremendous forces are generated at the shoulder joint, at times up to one times body weight. Because of these tremendous demands, at incredible angular velocities, various shoulder injuries may occur. An understanding of the biomechanics of throwing will assist the clinician in the recognition of various injuries and their specific treatment approaches. In this paper, we discuss the biomechanics of the overhead throwing motion for baseball as well as football.
Correct biomechanics minimise the risk of injury and improve performance during baseball pitching. The mechanics of 20 youth pitchers were analysed during outdoor practice using digital camcorders and a checklist of kinematic and temporal elements. The pitchers were also analysed indoors with a six-camera 240Hz Motion Analysis System. In both conditions, mechanics were graded using accepted norms for youth pitchers. Kappa coefficients were calculated between the qualitative measurements and motion analysis data for 17 kinematic parameters. 11 variables showed acceptable relationships between qualitative and quantitative data, indicating the practical value of this qualitative analysis as a field tool.
Pitching biomechanics are associated with performance and risk of injury in baseball. Previous studies have identified biomechanical differences between youth and adult pitchers but have not investigated changes within individual young pitchers as they mature.Pitching kinematics and kinetics will change significantly during a youth pitcher's career.Descriptive laboratory study.Pitching biomechanics were captured in an indoor laboratory with a 12-camera, 240-Hz motion analysis system for 51 youth pitchers who were in their first season of organized baseball with pitching. Each participant was retested annually for the next 6 years or until he was no longer pitching. Thirty kinematic and kinetic parameters were computed and averaged for 10 fastballs thrown by each player. Data were statistically analyzed for the 35 participants who were tested at least 3 times. Within-participant changes for each kinematic and kinetic parameter were tested by use of a mixed linear model with random effects ( P < .05). Least squares means for sequential ages were compared via Tukey's honestly significant difference test ( P < .05).Three kinematic parameters that occur at the instant of foot contact-stride length, lead foot placement to the closed side, and trunk separation-increased with age. With age, shoulder external rotation at foot contact decreased while maximum shoulder external rotation increased. Shoulder and elbow forces and torques increased significantly with age. Year-to-year changes were most significant between 9 and 13 years of age for kinematics and between 13 and 15 years for normalized kinetics (ie, scaled by bodyweight and height).During their first few years, youth pitchers improve their kinematics. Elbow and shoulder kinetics increase with time, particularly after age 13. Thus, prepubescent pitchers may work with their coaches to improve the motions and flexibility of the players' bodies and the paths of their arms. Once proper mechanics are developed, adolescent pitchers can focus more on improving strength and power.
Meniscocapsular separations are often seen in knees with other intra-articular pathology. The consequences of these tears with regard to knee contact mechanics are currently unknown, and the biomechanical advantages of repair have not been measured. We hypothesize that tears to the meniscocapsular junction will cause an increase in tibiofemoral contact pressure and a decrease in contact area, with a return to more normal conditions after repair. 10 fresh-frozen cadaver knees each underwent 10 cycles of axial compressive loading in full extension under three different testing conditions: intact, meniscocapsular separation, and repair. A pressure sensor matrix was inserted into the medial joint space and used to measure magnitude and location of contact pressure and area. Mean contact pressure increased from 0.80±0.17 MPa in the intact knee to 0.88±0.19 MPa with separation, with a decrease to 0.78±0.14 MPa following repair. Peak pressures followed a similar trend with 2.59±0.41, 3.03±0.48, and 2.84±0.40 MPa for the same three groups, respectively. While none of the changes seen was statistically significant, even these small changes would potentially create degenerative changes at the articular surface over prolonged (i. e., months or years) standing, walking, and activity in the unrepaired state.
Baseball pitchers who undergo SLAP (superior labrum, anterior to posterior) repair often have trouble returning to their previous level of performance. While the reason is often assumed to be diminished shoulder range of motion or other mechanical changes, differences in pitching biomechanics following surgery have not been previously studied. Pitching biomechanics were compared retrospectively between collegiate and professional pitchers with a history of a SLAP repair (n=10) and a control group (n=40) with no history of surgery. Full body biomechanics were compared between the two groups. For each comparison, a Student’s t-test was used at an a level of 0.05. Pitchers with history of SLAP repair produce less shoulder external rotation, shoulder horizontal abduction, and trunk forward tilt during pitching than pitchers with no history of injury.
