Documentation of the lower extremity motion patterns of adolescent pitchers is an important part of understanding the pitching motion and the implication of lower extremity technique on upper extremity loads, injury and performance. The purpose of this study was to take the initial step in this process by documenting the biomechanics of the lower extremities during the pitching cycle in adolescent pitchers and to compare these findings with the published data for older pitchers. Three-dimensional motion analysis using a comprehensive lower extremity model was used to evaluate the fast ball pitch technique in adolescent pitchers. Thirty-two pitchers with a mean age of 12.4 years (range 10.5–14.7 years) and at least 2 years of experience were included in this study. The pitchers showed a mean of 49 ± 12° of knee flexion of the lead leg at foot contact. They tended to maintain this position through ball release, and then extended their knee during the follow through phase (ball release to maximal internal glenohumeral rotation). The lead leg hip rapidly progressed into adduction and flexion during the arm cocking phase with a range of motion of 40 ± 10° adduction and 30 ± 13° flexion. The lead hip mean peak adduction velocity was 434 ± 83°/s and flexion velocity was 456 ± 156°/s. Simultaneously, the trailing leg hip rapidly extended approaching to a mean peak extension of –8 ± 5° at 39% of the pitch cycle, which is close to passive range of motion constraints. Peak hip abduction of the trailing leg at foot contact was –31 ± 12°, which also approached passive range of motion constraints. Differences and similarities were also noted between the adolescent lower extremity kinematics and adult pitchers; however, a more comprehensive analysis using similar methods is needed for a complete comparison.
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Adolescent Baseball Pitching Technique: Lower Extremity Biomechanical Analysis
Matthew D. Milewski, Sylvia Õunpuu, Matthew Solomito, Melany Westwell, and Carl W. Nissen
The Effects of Track Turns on Lower Extremity Function
Joseph Hamill, Michael Murphy, and Donald Sussman
The mechanics of moving along a curved path suggest that runners must change their body positions and thus adjust their lower extremity function as they accomplish a track turn. The purpose of the present study was to investigate the changes in the kinetics and kinematics of the lower extremity as runners proceed around the turn of a 400-m track (radius 31.5 m). Five skilled runners served as subjects in the study and were required to perform 10 trials in three conditions, running at 6.31 m/s plus or minus 5% (4:15 min/mile pace). The right and left limbs on a track turn and the right limb on the straightaway were evaluated using ground reaction force data and kinematic data from high-speed film. Statistical analysis of the 18 ground reaction force variables and 4 kinematic variables suggested that the right and left limbs at the midpoint of the track turn were asymmetrical and that most of the differences occurred in the first portion of the footfall Significant differences were found in the touchdown angle, maximum pronation angle, all mediolateral variables, and in the vertical variables describing the collision phase of the footfall (p < .05). The data suggest that the etiologies of injuries to the right and left lower extremity differ, with right foot injuries being of the impact type and left leg injuries being of the overpronation type.
Acute Static Stretching Reduces Lower Extremity Power in Trained Children
Jeni R. McNeal and William A. Sands
Several studies utilizing adult subjects have indicated that static stretching may reduce subsequent strength and power production, possibly for as long as an hour following the stretch. This observation has not been evaluated in children, nor in athletes accustomed to performing static stretches during strength/power type training sessions. The purpose of this investigation was to determine if an acute bout of passive, static stretching of the lower extremity would affect jumping performance in a group of young, female gymnasts. Thirteen competitive gymnasts (age 13.3 − 2.6 yrs) performed drop jumps under two conditions: immediately following stretching and without prior stretching. The jumps were performed on separate days. The conditions were randomly ordered among the subjects. Time in the air (AIR) and ground contact time (CT) were measured during the drop jumps using a timing mat. Three different stretches of the lower extremity were conducted on each gymnast twice, each stretch being held for 30 seconds. Following the stretching condition, AIR was significantly reduced (.44 vs .46 sec, p < .001), while CT was not different (.130 for both conditions, p > .05). This study demonstrates that children’s lower extremity power is reduced when the performance immediately follows passive, static stretching, even in children accustomed to static stretching during training sessions involving explosive power.
The Relationship Between Health-Related Quality of Life and Lower-Extremity Visuomotor Reaction Time in Young Adult Women Following Ankle Sprain
Katherine A. Bain, Shelby Baez, Kyle B. Kosik, Matthew C. Hoch, Johanna M. Hoch, Nathan F. Johnson, Richard D. Andreatta, and Phillip A. Gribble
subjective outcomes assessing domains of HRQOL in individuals with a history of LAS. Poorly rated HRQOL can negatively impact neurocognitive performance and create attentional disruptions that suggest the need to better understand the relationship between constructs of self-reported HRQOL and lower-extremity
Does Neuromuscular Training Reduce the Risk of Lower-Extremity Musculoskeletal Injury in High School Female Athletes With a History of Sport-Related Concussion?
April L. McPherson, Taylor M. Zuleger, Kim D. Barber Foss, Shayla M. Warren, Jennifer A. Hogg, Jed A. Diekfuss, and Gregory D. Myer
History of sport-related concussion (SRC) increases the risk for future lower-extremity musculoskeletal (LE MSK) injury across all ages and levels of sport (eg, high school, college, and professional). 1 – 5 SRCs in adolescent athletes are of particular importance since an estimated 1.1 to 1
A Perturbation Study of Lower Extremity Motion during Running
Wilbert Van Woensel and Peter R. Cavanagh
The present study explored kinematic adaptation in the lower extremity to running in shoes with 10° valgus and varus midsole perturbations. Rearfoot motion and knee flexion/extension data on nine subjects were collected using a Selspot II system during treadmill running in the two test shoes and in a neutral shoe condition. Maximum pronation was significantly altered by an amount approximately the same as the shoe perturbation, but there was no substantial adaptation in the amount of knee flexion. From the rearfoot patterns it was inferred that time to maximum pronation may be an unreliable variable to describe the pattern of rearfoot motion; the two-phase profile using rearfoot velocity may be more useful. It was concluded that certain subtle sagittal plane kinematic adaptations in timing and velocity patterns did occur at the knee in response to the shoe perturbations.
Hip Abductor Weakness and Lower Extremity Kinematics during Running
Becky L. Heinert, Thomas W. Kernozek, John F. Greany, and Dennis C. Fater
Objective:
To determine if females with hip abductor weakness are more likely to demonstrate greater knee abduction during the stance phase of running than a strong hip abductor group.
Study Design:
Observational prospective study design.
Setting:
University biomechanics laboratory.
Participants:
15 females with weak hip abductors and 15 females with strong hip abductors.
Main Outcome Measures:
Group differences in lower extremity kinematics were analyzed using repeated measures ANOVA with one between factor of group and one within factor of position with a significance value of P < .05.
Results:
The subjects with weak hip abductors demonstrated greater knee abduction during the stance phase of treadmill running than the strong group (P < .05). No other significant differences were found in the sagittal or frontal plane measurements of the hip, knee, or pelvis.
Conclusions:
Hip abductor weakness may influence knee abduction during the stance phase of running.
Lower-Extremity Electromyography Measures During Walking With Ankle-Destabilization Devices
Luke Donovan, Joseph M. Hart, and Jay Hertel
Context:
Ankle-destabilization devices are rehabilitation tools that may improve neuromuscular control by increasing lower-extremity muscle activation. Their effects should be tested in healthy individuals before being implemented in rehabilitation programs.
Objective:
To compare EMG activation of lower-extremity muscles during walking while wearing 2 different ankle-destabilization devices.
Design:
Crossover.
Setting:
Laboratory.
Participants:
15 healthy young adults (5 men, 10 women).
Intervention:
Surface EMG activity was recorded from the anterior tibialis, peroneus longus, lateral gastrocnemius, rectus femoris, biceps femoris, and gluteus medius as subjects walked on a treadmill shod, with an ankle-destabilization boot (ADB), and an ankle-destabilization sandal (ADS).
Main Outcome Measures:
Normalized amplitudes 100 ms before and 200 ms after initial heel contact, time of onset activation relative to initial contact, and percent of activation time across the stride cycle were calculated for each muscle in each condition.
Results:
The precontact amplitudes of the peroneus longus and lateral gastrocnemius and the postcontact amplitudes of the lateral gastrocnemius were significantly greater in the ADB and ADS conditions. In the ADB condition, the rectus femoris and biceps femoris postcontact amplitudes were significantly greater than shod. The peroneus longus and lateral gastrocnemius were activated significantly earlier, and the anterior tibialis, lateral gastrocnemius, and rectus femoris were activated significantly longer across the stride cycle in the ADB and the ADS conditions. In addition, the peroneus longus was activated significantly longer in the ADB condition when compared with shod.
Conclusions:
Both ankle-destabilization devices caused an alteration in muscle activity during walking, which may be favorable to an injured patient. Therefore, implementing these devices in rehabilitation programs may be beneficial to improving neuromuscular control.
The Effects of Self-Myofascial Release on Flexibility of the Lower Extremity: A Critically Appraised Topic
Christine M. Feldbauer, Brittany A. Smith, and Bonnie Van Lunen
Clinical Question:
Does self-myofascial release improve lower extremity fexibility or range of motion in physically active individuals?
Clinical Bottom Line:
There is low-level evidence to support the use of self-my-ofascial release to increase range of motion and fexibility in the lower extremity.
Lower Extremity Joint Moments During Carrying Tasks in Children
Jason C. Gillette, Catherine A. Stevermer, Ross H. Miller, W. Brent Edwards, and Charles V. Schwab
Farm youth often carry loads that are proportionally large and/or heavy, and field measurements have determined that these tasks are equivalent to industrial jobs with high injury risks. The purpose of this study was to determine the effects of age, load amount, and load symmetry on lower extremity joint moments during carrying tasks. Three age groups (8–10 years, 12–14 years, adults), three load amounts (0%, 10%, 20% BW), and three load symmetry levels (unilateral large bucket, unilateral small bucket, bilateral small buckets) were tested. Inverse dynamics was used to determine maximum ankle, knee, and hip joint moments. Ankle dorsiflexion, ankle inversion, ankle eversion, knee adduction, and hip extension moments were significantly higher in 8–10 and 12–14 year olds. Ankle plantar flexion, ankle inversion, knee extension, and hip extension moments were significantly increased at 10% and 20% BW loads. Knee and hip adduction moments were significantly increased at 10% and 20% BW loads when carrying a unilateral large bucket. Of particular concern are increased ankle inversion and eversion moments for children, along with increased knee and hip adduction moments for heavy, asymmetrical carrying tasks. Carrying loads bilaterally instead of unilaterally avoided increases in knee and hip adduction moments with increased load amount.
