Running to the beat: Does listening to music affect running cadence and lower extremity biomechanics?

BACKGROUND: Gait retraining can be effective in altering lower extremity biomechanics and reducing risk of injury. In attempts to alter running gait, previous studies used metronomes to manipulate cadence. RESEARCH QUESTION: The aim of this study was to determine if manipulating running cadence via music could alter lower extremity biomechanics. METHODS: Eighteen runners ran at a self-selected speed (SS) and ran to music where the beats per minute (bpm) of the songs was increased by 5% (+5%) and 10% (+10%). Kinematic and kinetic data were collected with a motion capture system and a triaxial accelerometer. A one-way repeated measures analysis of variance (ANOVA) was applied to test the effect of bpm (SS, +5%, +10%) on cadence, heart rate and peak vertical acceleration. A statistical parametric mapping (SPM) one-way repeated measures ANOVA was used to test the effect of bpm on the sagittal plane kinematic signals during stance phase. RESULTS: There was a significant main effect for bpm on the discrete metrics. Post hoc tests showed significant differences in heartrate from SS to + 5%, + 5% to + 10%, and SS to 10%. There were no significant differences between cadence or peak acceleration. SIGNIFICANCE: In the current study, listening to music with faster bpm was not shown to increase cadence and decrease peak tibial accelerations during running.

Hip Strength and Pitching Biomechanics in Adolescent Baseball Pitchers.

CONTEXT: Hip strength may influence the energy flow through the kinematic chain during baseball pitching, affecting athlete performance as well as the risk for injury. OBJECTIVE: To identify associations between hip strength and pitching biomechanics in adolescent baseball pitchers during 3 key events of the pitching cycle. DESIGN: Cross-sectional study. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: A total of 26 adolescent male baseball pitchers (age = 16.1 ± 0.8 years, height = 184.29 ± 5.5 cm, mass = 77.5 ± 8.5 kg). MAIN OUTCOME MEASURE(S): The main outcome measure was hip strength (external rotation, internal rotation, flexion, abduction, adduction, and extension). After strength measurements were acquired, motion capture was used to obtain a full-body biomechanical analysis at 3 events during the pitching cycle (foot contact, maximal external rotation, and ball release). We then evaluated these values for associations between hip strength and pitching biomechanics. Scatterplots were examined for linearity to identify an appropriate correlation test. The associations were linear; thus, 2-tailed Pearson correlation coefficients were used to determine correlations between biomechanical metrics. An α level of .01 was chosen. RESULTS: Ten strong correlations were found between pitching biomechanics and hip strength: 8 correlations between hip strength and kinematics at key points during the pitch and 2 correlations of hip strength with peak elbow-varus torque. CONCLUSIONS: Several correlations were noted between lower extremity strength and pitching biomechanics. This information provides data that may be used to improve performance or reduce injury (or both) in pitchers. Increased hip strength in adolescent pitchers may both improve performance and decrease the risk of injury.

Relationships Among Shoulder Rotational Strength, Range of Motion, Pitching Kinetics, and Pitch Velocity in Collegiate Baseball Pitchers.

ABSTRACT: Cross, JA, Higgins, AW, Dziuk, CC, Harris, GF, and Raasch, WG. Relationships among shoulder rotational strength, range of motion, pitching kinetics, and pitch velocity in collegiate baseball pitchers. J Strength Cond Res 37(1): 129-135, 2023-Throwing shoulder injuries are the most common type of injury experienced by baseball pitchers. Weakness in the shoulder musculature and insufficient throwing arm range of motion are both risk factors for developing a shoulder injury. The goal of this study was to determine correlations among shoulder rotational strength, range of motion, pitching kinetics, and pitch velocity in collegiate pitchers. Thirteen uninjured male college pitchers were evaluated. Clinical measures included shoulder internal and external rotation range of motion, peak isokinetic internal and external rotator strength, and peak isometric internal and external rotator strength. Three-dimensional biomechanics were assessed as subjects threw from an indoor pitching mound to a strike zone net at regulation distance. Pearson's correlations were used to assess the associations among the clinical measures and throwing metrics. Five significant correlations were found between peak shoulder compressive force and strength, and 4 significant correlations were found between pitching velocity and strength ( p < 0.05). No significant correlations were found between range of motion and pitching kinetics or velocity. Our results suggest that as shoulder rotational strength increases, the peak shoulder compressive force and pitch velocity both increase. Knowledge of relationships between strength metrics and pitching biomechanics may allow for improved strength training routines with the goal of increasing velocity without increasing injury risk.

Hip Flexibility and Pitching Biomechanics in Adolescent Baseball Pitchers.

CONTEXT: Inadequate hip active range of motion (AROM) may stifle the energy flow through the kinematic chain and decrease pitching performance while increasing the risk for pitcher injury. OBJECTIVE: To examine the relationship between hip AROM and pitching biomechanics during a fastball pitch in adolescent baseball pitchers. DESIGN: Cross-sectional study. SETTING: Biomechanics laboratory. PATIENTS OR OTHER PARTICIPANTS: A sample of 21 adolescent male baseball pitchers (age = 16.1 ± 0.8 years, height = 183.9 ± 5.2 cm, mass = 77.9 ± 8.3 kg). MAIN OUTCOME MEASURE(S): Bilateral hip external-rotation (ER), internal-rotation, flexion, abduction, and extension AROM were measured. Three-dimensional biomechanics were assessed as participants threw from an indoor pitching mound to a strike-zone net at regulation distance. Pearson product moment correlation coefficients were used to determine relationships between hip AROM and biomechanical metrics. RESULTS: Negative correlations were found at foot contact between back-hip ER AROM and torso-rotation angle (r = -0.468, P = .03), back-hip ER AROM and back-hip abduction angle (r = -0.474, P = .03), and back-hip abduction AROM and lead-hip abduction angle (r = -0.458, P = .04). Back-hip extension AROM was positively correlated with increased stride length (r = 0.446, P = .043). Lead-hip abduction AROM was also positively correlated with normalized elbow-varus torque (r = 0.464, P = .03). CONCLUSIONS: We observed several relationships between hip AROM and biomechanical variables during the pitching motion. These findings support the influence that hip AROM can have on pitching biomechanics. Overall, greater movement at the hips allows the kinematic chain to work at maximal efficiency, increasing the pitch velocity potential.

Sagittal Subtalar and Talocrural Joint Assessment During Ambulation With Controlled Ankle Movement (CAM) Boots.

BACKGROUND: The purpose of the current study was to determine sagittal plane talocrural and subtalar kinematic differences between barefoot and controlled ankle movement (CAM) boot walking. This study used fluoroscopic images to determine talar motion relative to tibia and calcaneal motion relative to talus. METHODS: Fourteen male subjects (mean age 24.1 ± 3.5 years) screened for normal gait were tested. A fluoroscopy unit was used to collect images at 200 Hz during stance. Sagittal motion of the talocrural and subtalar joints were analyzed barefoot and within short and tall CAM boots. RESULTS: Barefoot talocrural mean maximum plantar and dorsiflexion were 9.2 ± 5.4 degrees and -7.5 ± 7.4 degrees, respectively; short CAM boot mean maximum plantar and dorsiflexion were 3.2 ± 4.0 degrees and -4.8 ± 10.2 degrees, respectively; and tall CAM boot mean maximum plantar and dorsiflexion were -0.2 ± 3.5 degrees and -2.4 ± 5.1 degrees, respectively. Talocrural mean range of motion (ROM) decreased from barefoot (16.7 ± 5.1 degrees) to short CAM boot (8.0 ± 4.9 degrees) to tall CAM boot (2.2 ± 2.5 degrees). Subtalar mean maximum plantarflexion angles were 5.3 ± 5.6 degrees for barefoot walking, 4.1 ± 5.9 degrees for short CAM boot walking, and 3.0 ± 4.7 degrees for tall CAM boot walking. Mean minimum subtalar plantarflexion angles were 0.7 ± 3.2 degrees for barefoot walking, 0.7 ± 2.9 degrees for short CAM boot walking, and 0.1 ± 4.8 degrees for tall CAM boot walking. Subtalar mean ROM decreased from barefoot (4.6 ± 3.9 degrees) to short CAM boot (3.4 ± 3.8 degrees) to tall CAM boot (2.9 ± 2.6 degrees). CONCLUSION: Tall and short CAM boot intervention was shown to limit both talocrural and subtalar motion in the sagittal plane during ambulation. The greatest reductions were seen with the tall CAM boot, which limited talocrural motion by 86.8% and subtalar motion by 37.0% compared to barefoot. Short CAM boot intervention reduced talocrural motion by 52.1% and subtalar motion by 26.1% compared to barefoot. CLINICAL RELEVANCE: Both short and tall CAM boots reduced talocrural and subtalar motion during gait. The short CAM boot was more convenient to use, whereas the tall CAM boot more effectively reduced motion. In treatments requiring greater immobilization of the talocrural and subtalar joints, the tall CAM boot should be considered.

Biplane fluoroscopy for hindfoot motion analysis during gait: A model-based evaluation.

The purpose of this study was to quantify the accuracy and precision of a biplane fluoroscopy system for model-based tracking of in vivo hindfoot motion during over-ground gait. Gait was simulated by manually manipulating a cadaver foot specimen through a biplane fluoroscopy system attached to a walkway. Three 1.6-mm diameter steel beads were implanted into the specimen to provide marker-based tracking measurements for comparison to model-based tracking. A CT scan was acquired to define a gold standard of implanted bead positions and to create 3D models for model-based tracking. Static and dynamic trials manipulating the specimen through the capture volume were performed. Marker-based tracking error was calculated relative to the gold standard implanted bead positions. The bias, precision, and root-mean-squared (RMS) error of model-based tracking was calculated relative to the marker-based measurements. The overall RMS error of the model-based tracking method averaged 0.43 ± 0.22mm and 0.66 ± 0.43° for static and 0.59 ± 0.10mm and 0.71 ± 0.12° for dynamic trials. The model-based tracking approach represents a non-invasive technique for accurately measuring dynamic hindfoot joint motion during in vivo, weight bearing conditions. The model-based tracking method is recommended for application on the basis of the study results.

Quantifying cross-scatter contamination in biplane fluoroscopy motion analysis systems.

Biplane fluoroscopy is used for dynamic in vivo three-dimensional motion analysis of various joints of the body. Cross-scatter between the two fluoroscopy systems may limit tracking accuracy. This study measured the magnitude and effects of cross-scatter in biplane fluoroscopic images. Four cylindrical phantoms of 4-, 6-, 8-, and 10-in. diameter were imaged at varying kVp levels to determine the cross-scatter fraction and contrast-to-noise ratio (CNR). Monte Carlo simulations quantified the effect of the gantry angle on the cross-scatter fraction. A cadaver foot with implanted beads was also imaged. The effect of cross-scatter on marker-based tracking accuracy was investigated. Results demonstrated that the cross-scatter fraction varied from 0.15 for the 4-in. cylinder to 0.89 for the 10-in. cylinder when averaged across kVp. The average change in CNR due to cross-scatter ranged from 5% to 36% CNR decreases for the 4- and 10-in. cylinders, respectively. In simulations, the cross-scatter fraction increased with the gantry angle for the 8- and 10-in. cylinders. Cross-scatter significantly increased static-tracking error by 15%, 25%, and 38% for the 6-, 8-, and 10-in. phantoms, respectively, with no significant effect for the foot specimen. The results demonstrated submillimeter marker-based tracking for a range of phantom sizes, despite cross-scatter degradation.