Biomedical subjects

Glenn S Fleisig

Publications and source records attributed to Glenn S Fleisig.

13 recordsLinked to original sources

PubMed2006

Pitching biomechanics as a pitcher approaches muscular fatigue during a simulated baseball game.

BACKGROUND: The effects of approaching muscular fatigue on pitching biomechanics are currently unknown. As a pitcher fatigues, pitching mechanics may change, leading to a decrease in performance and an increased risk of injury. HYPOTHESIS: As a pitcher approaches muscular fatigue, select pitching biomechanical variables will be significantly different than they were before muscular fatigue. STUDY DESIGN: Controlled laboratory study. METHODS: Ten collegiate baseball pitchers threw 15 pitches per inning for 7 to 9 innings off an indoor throwing mound during a simulated baseball game. A pitching session ended when each pitcher felt he could no longer continue owing to a subjective perception of muscular fatigue. A 6-camera 3D automatic digitizing system collected 200-Hz video data. Twenty kinematic and 11 kinetic variables were calculated throughout 4 phases of the pitch. A repeated-measure analysis of variance (P < .01) was used to compare biomechanical variables between innings. RESULTS: Compared with the initial 2 innings, as a pitcher approached muscular fatigue during the final 2 innings he was able to pitch, there was a significant decrease in ball velocity, and the trunk was significantly closer to a vertical position. There were no other significant differences in kinematics or kinetics variables. CONCLUSION: The relatively few differences observed imply that pitching biomechanics remained remarkably similar between collegiate starting pitchers who threw between 105 and 135 pitches for 7 to 9 innings and approached muscular fatigue. CLINICAL RELEVANCE: This study did not support the idea that there is an increase in shoulder and elbow forces and torques as muscular fatigue is approached. It is possible that if a pitcher remained in a fatigued state for a longer period of time, additional changes in pitching mechanics may occur and the risk of injury may increase.

Adult↗

PubMed2006

The relationship between age and baseball pitching kinematics in professional baseball pitchers.

Joint range of motion and physical capacities have been shown to change with age in both throwing athletes and non-athletes. The age of professional baseball pitchers could span from late teens to mid-40s. However, the effects of age on the pitching kinematics among professional baseball pitchers are still unknown. In this study, 67 healthy professional baseball pitchers were tested using a 3D motion analysis system. Their mean age was 23.7+/-3.3 years (range 18.8-34.4). The 12 pitchers more than one standard deviation older than the mean (i.e., older than 27.0 years) were categorized into the older group, and the 10 pitchers more than one standard deviation younger than the mean (i.e., younger than 20.4 years) were defined as the younger group. In all, 18 kinematic variables (14 position and 4 velocity) were calculated, and Student's t-tests were used to compare the variables between the two groups. Six position variables were found to be significantly different between the two groups. At the instant of lead foot contact, the older group had a shorter stride, a more closed pelvis orientation, and a more closed upper trunk orientation. The older group also produced less shoulder external rotation during the arm cocking phase, more lead knee flexion at ball release, and less forward trunk tilt at ball release. Ball velocity and body segment velocity variables showed no significant differences between the two groups. Thus, differences in specific pitching kinematic variables among professional baseball pitchers of different age groups were not associated with significant differences in ball velocities between groups. The current results suggest that both biological changes and technique adaptations occur during the career of a professional baseball pitcher.

Adolescent↗

PubMed2006

Risk factors for shoulder and elbow injuries in adolescent baseball pitchers.

BACKGROUND: There is little evidence supporting current safety recommendations for adolescent pitchers. HYPOTHESIS: Pitching practices of adolescent pitchers without history of arm injury will be significantly different from those of adolescent pitchers who required shoulder or elbow surgery. STUDY DESIGN: Case control study; Level of evidence, 3. METHODS: Ninety-five adolescent pitchers who had shoulder or elbow surgery and 45 adolescent pitchers who never had a significant pitching-related injury completed a survey. Responses were compared between the 2 groups using t tests and chi(2) analyses. Multivariable logistic regression models were developed to identify the risk factors. RESULTS: The injured group pitched significantly more months per year, games per year, innings per game, pitches per game, pitches per year, and warm-up pitches before a game. These pitchers were more frequently starting pitchers, pitched in more showcases, pitched with higher velocity, and pitched more often with arm pain and fatigue. They also used anti-inflammatory drugs and ice more frequently to prevent an injury. Although the groups were age matched, the injured group was taller and heavier. There were no significant differences regarding private pitching instruction, coach's chief concern, pitcher's self-rating, exercise programs, stretching practices, relieving frequency, pitch type frequency, or age at which pitch types were first thrown. CONCLUSION: Pitching practices were significantly different between the groups. The factors with the strongest associations with injury were overuse and fatigue. High pitch velocity and participation in showcases were also associated with increased risk for injury. CLINICAL RELEVANCE: New recommendations were made based on these results. Adherence to the recommendations may reduce the incidence of significant injury to adolescent pitchers.

Adolescent↗

PubMed2006

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.

Abdomen↗

PubMed2005

Kinetic comparison among the fastball, curveball, change-up, and slider in collegiate baseball pitchers.

BACKGROUND: Controversy exists about whether breaking pitches are more stressful than are fastballs. Previous biomechanical studies compared kinematics but not kinetics. HYPOTHESIS: Elbow and shoulder forces and torques are statistically different among the fastball, curveball, change-up, and slider. STUDY DESIGN: Descriptive laboratory study. METHODS: Twenty-one healthy collegiate pitchers were studied with a high-speed automated digitizing system. All subjects threw fastballs (n = 21), most threw curveballs (n = 20) and change-ups (n = 19), and a few threw sliders (n = 6). Wrist, elbow, and shoulder kinetics were calculated using inverse dynamics. Nine kinetic and 26 kinematic parameters were compared among the different pitch types using repeated-measures analysis of variance. RESULTS: At the shoulder, internal rotation torque, horizontal adduction torque, abduction torque, and proximal force were significantly less in the change-up than in the other 3 pitches. Shoulder horizontal adduction torque was greater in the fastball than in the curveball and slider. Shoulder proximal force was greater in the slider than in the curveball. Elbow proximal force was less in the change-up than in the other 3 pitches. Elbow varus torque was greater in the fastball and curveball than in the change-up. Elbow flexion torque was greater in the curveball than in the change-up. The curveball and change-up demonstrated kinematic differences from the fastball, consistent with previous studies. CONCLUSION: There were significant kinematic differences between the fastball and curveball but few kinetic differences. The change-up had lower joint kinetics, lower angular velocities, and different body positions than the other 3 pitch types had. Results for the slider were inconclusive because of small sample size. CLINICAL RELEVANCE: Because the resultant joint loads were similar between the fastball and curveball, this study did not indicate that either pitch was more stressful or potentially dangerous for a collegiate pitcher. The low kinetics in the change-up implies that it is the safest.

Adult↗

PubMed2005

Relationship of biomechanical factors to baseball pitching velocity: within pitcher variation.

To reach the level of elite, most baseball pitchers need to consistently produce high ball velocity but avoid high joint loads at the shoulder and elbow that may lead to injury. This study examined the relationship between fastball velocity and variations in throwing mechanics within 19 baseball pitchers who were analyzed via 3-D high-speed motion analysis. Inclusion in the study required each one to demonstrate a variation in velocity of at least 1.8 m/s (range 1.8-3.5 m/s) during 6 to 10 fastball pitch trials. Three mixed model analyses were performed to assess the independent effects of 7 kinetic, 11 temporal, and 12 kinematic parameters on pitched ball velocity. Results indicated that elbow flexion torque, shoulder proximal force, and elbow proximal force were the only three kinetic parameters significantly associated with increased ball velocity. Two temporal parameters (increased time to max shoulder horizontal adduction and decreased time to max shoulder internal rotation) and three kinematic parameters (decreased shoulder horizontal adduction at foot contact, decreased shoulder abduction during acceleration, and increased trunk tilt forward at release) were significantly related to increased ball velocity. These results point to variations in an individual's throwing mechanics that relate to pitched ball velocity, and also suggest that pitchers should focus on consistent mechanics to produce consistently high fastball velocities. In addition, pitchers should strengthen shoulder and elbow musculature that resist distraction as well as improve trunk strength and flexibility to maximize pitching velocity and help prevent injury.

Acceleration↗

PubMed2005

Baseball injuries.

OBJECTIVE: To identify the frequency of injury in youth baseball, risk factors for these injuries, and possible prevention measures to reduce the frequency or severity of these injuries. DATA SOURCES: Information was collected from all known epidemiologic and intervention studies published in the peer-reviewed medical and scientific literature as it applies to youth baseball injuries. MAIN RESULTS: The frequency and severity of youth baseball injuries have remained relatively consistent over time. Risk factors for many injuries have been understudied and the study designs used for much of this research have been less than optimal. Several effective prevention measures have been identified, such as batting helmets, face shields, softer baseballs, and breakaway bases. CONCLUSIONS: Baseball is a relatively safe sport compared to many contact sports, but injuries do still occur. Future research should focus on determining the optimum pitching motion for both arm safety and performance, as well as systematically studying other potential safety improvements such as restrictions against breaking pitches.

Athletic Injuries↗

PubMed2004

Ulnar collateral ligament reconstruction in high school baseball players: clinical results and injury risk factors.

BACKGROUND: The incidence of ulnar collateral ligament injury has increased in baseball, especially at the high school level. HYPOTHESIS: Ulnar collateral ligament injury in high school baseball players is associated with overuse, high-velocity throwing, early throwing of breaking pitches, and improper warm-ups. STUDY DESIGN: Retrospective cohort study. METHODS: Follow-up physical examination and questionnaire data were collected at an average of 35 months after ulnar collateral ligament reconstruction from 27 former high school baseball players. Six potential risk factors were evaluated: year-round throwing, seasonal overuse, event overuse, throwing velocity more than 80 mph, throwing breaking pitches before age 14, and inadequate warm-ups. RESULTS: Overall, 74% returned to baseball at the same or higher level. Patients averaged 3 potential risk factors, and 85% demonstrated at least one overuse category. Of the pitchers, the average self-reported fastball velocity was 83 mph, and 67% threw breaking pitches before age 14. CONCLUSIONS: The success rate of ulnar collateral ligament reconstruction in high school baseball players is nearly equal to that in more mature groups of throwers. Overuse of the throwing arm and throwing breaking pitches at an early age may be related to their injuries. Special attention should be paid to elite-level teenage pitchers who throw with high velocity.

Adolescent↗

PubMed2004

Biomechanics of the elbow in sports.

In throwing activities, the elbow is sometimes stressed to its biomechanical limits. In this article, forces, torques, angular velocities, and muscle activity about the elbow are reviewed for the baseball pitch, the football pass, the javelin throw, the windmill softball pitch, the tennis serve, and the golf swing. The elbow goes through rapid extension in baseball pitching (about 2400 degrees/s) and rapid flexion in the javelin throw (about 1900 degrees/s). During baseball pitching, the elbow joint is subject to a valgus torque reaching 64 Nm, and requires proximal forces as high as 1000 N to prevent elbow distraction. The ulnar collateral ligament (UCL) rupture in baseball pitching, lateral epicondylitis in the tennis backhand, and other injury mechanisms are also discussed.

Baseball↗

PubMed2004

Change in plantarflexion strength after complete detachment and reconstruction of the Achilles tendon.

BACKGROUND: Chronic insertional tendinitis of the Achilles tendon is an overuse injury seen with increasing frequency because of an aging population and an increased interest in sports. We evaluated the change in plantarflexion strength in patients after our surgical technique for chronic insertional Achilles tendinitis. METHODS: From our previous clinical series of detachment and reconstruction of the Achilles tendon for the treatment of insertional tendinitis, ten patients were evaluated with an average followup of 32.1 (range 18 to 52) months. The average age was 65.7 years. We developed a mathematical model to predict the difference in plantarflexion strength between a reconstructed ankle and a healthy contralateral one. Isokinetic testing at 60 degrees/second was performed, measuring plantarflexion peak torque, dorsiflexion peak torque, and total work. RESULTS: Our mathematical model predicted a decrease of 4% in plantarflexion torque after the surgery. Isokinetic testing found no significant differences in plantarflexion torque, dorsiflexion torque, or total work between the operated and nonoperated ankles. CONCLUSIONS: Complete detachment and reconstruction of the Achilles tendon do not decrease the working capacity of the gastrocsoleus muscle.

Achilles Tendon↗

PubMed2004

Electromyographic analysis of the rotator cuff and deltoid musculature during common shoulder external rotation exercises.

STUDY DESIGN: Prospective single-group repeated-measures design. OBJECTIVES: To quantify electromyographic (EMG) muscle activity of the infraspinatus, teres minor, supraspinatus, posterior deltoid, and middle deltoid during exercises commonly used to strengthen the shoulder external rotators. BACKGROUND: Exercises to strengthen the external rotators are commonly prescribed in rehabilitation, but the amount of EMG activity of the infraspinatus, teres minor, supraspinatus, and deltoid during these exercises has not been thoroughly studied to determine which exercises would be most effective to achieve strength gains. METHODS AND MEASURES: EMG measured using intramuscular electrodes were analyzed in 10 healthy subjects during 7 shoulder exercises: prone horizontal abduction at 100 degrees of abduction and full external rotation (ER), prone ER at 90 degrees of abduction, standing ER at 90 degrees of abduction, standing ER in the scapular plane (45 degrees abduction, 30 degrees horizontal adduction), standing ER at 0 degrees of abduction, standing ER at 0 degrees of abduction with a towel roll, and sidelying ER at 0 degrees of abduction. The peak percentage of maximal voluntary isometric contraction (MVIC) for each muscle was compared among exercises using a 1-way repeated-measures analysis of variance (P<.05). RESULTS: EMG activity varied significantly among the 7 exercises. Sidelying ER produced the greatest amount of EMG activity for the infraspinatus (62% MVIC) and teres minor (67% MVIC). The greatest amount of activity of the supraspinatus (82% MVIC), middle deltoid (87% MVIC), and posterior deltoid (88% MVIC) was observed during prone horizontal abduction at 100 degrees with full ER. CONCLUSIONS: Results from this study provide initial information to develop rehabilitation programs. It also provides information helpful for the design and conduct of future studies.

Adult↗

PubMed2003

Anchor enhanced capsulorraphy in bunionectomies using an L-shaped capsulotomy.

The objective of this study was to investigate potential benefit of a suture anchor-enhanced capsulorraphy in the early maintenance of correction in bunionectomies. We compared, retrospectively, in successive series, the loss of correction of the Hallux Valgus (HV) and intermetatarsal (IM) angle, in those repaired with an L-shaped capsulorraphy enhanced with anchors to those without. Intraoperative and second week postoperative simulated weightbearing anterior posterior (AP) X-rays were used to evaluate results. By using only intraoperative and early postoperative X-rays, we should have effectively eliminated extraneous factors that might have influenced our results. A Total of 106 cases were investigated, 65 of which were repaired using anchors, the remaining 41 without. In the anchor group, 38 underwent a proximal metatarsal concentric shelf osteotomy (CSO)/modified McBride procedure, while the remaining 27 had a distal Chevron correction. In the without-anchor group, 21 had a CSO/modified McBride procedure while 20 underwent the Chevron procedure. In the without-anchor group, the average HV and IM loss of correction was 4.60 degrees (range, -2 to 21 degrees) and 0.6 degrees (range, -1 to 9 degrees) respectively. In the anchor group, the corresponding loss was 2.8 degrees (range, -3 to 17 degrees) and 0.6 degrees (range, -2 to 14 degrees) respectively. These results, when statistically analyzed, demonstrated that while the IM angle change was not statistically significant, the HV angle change was statistically significant, implying that the anchor plays a significant role in maintaining the surgical correction in both the distal Chevron and CSO/ modified McBride bunionectomies.

Hallux Valgus↗

PubMedDate not supplied

Effect of pitch type, pitch count, and pitching mechanics on risk of elbow and shoulder pain in youth baseball pitchers.

BACKGROUND: Joint pain is thought to be an early sign of injury to a pitcher. OBJECTIVE: To evaluate the association between pitch counts, pitch types, and pitching mechanics and shoulder and elbow pain in young pitchers. STUDY DESIGN: Prospective cohort study. METHODS: Four hundred and seventy-six young (ages 9 to 14 years) baseball pitchers were followed for one season. Data were collected from pre- and postseason questionnaires, injury and performance interviews after each game, pitch count logs, and video analysis of pitching mechanics. Generalized estimating equations and logistic regression analysis were used. RESULTS: Half of the subjects experienced elbow or shoulder pain during the season. The curveball was associated with a 52% increased risk of shoulder pain and the slider was associated with an 86% increased risk of elbow pain. There was a significant association between the number of pitches thrown in a game and during the season and the rate of elbow pain and shoulder pain. CONCLUSIONS: Pitchers in this age group should be cautioned about throwing breaking pitches (curveballs and sliders) because of the increased risk of elbow and shoulder pain. Limitations on pitches thrown in a game and in a season can also reduce the risk of pain. Further evaluation of pain and pitching mechanics is necessary.

Adolescent↗