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Noah X. Tocci, David R. Howell, Dai Sugimoto, Corey Dawkins, Amy Whited, and Donald Bae

High elbow torque during a pitch may contribute to injury risk. Our objective was to determine the pitch mechanics associated with elbow varus torque in youth baseball pitchers. Eighteen male youth pitchers (age = 15.5 ± 1.6 years) threw 3 fastballs and 3 change-ups from a windup position while undergoing 3-dimensional kinematic analysis. Independent variables included ball release point distance, stride length, lateral pelvic tilt, and ball velocity. Two multiple regression models, separated by pitch type (fastball, change-up) were used to determine the association of independent variables with peak varus torque at the elbow. Fastball and change-up regression models indicated that stride length (β = 0.301, p = .015; β = 0.46, p < .001, respectively) and lateral pelvic tilt (β = −0.50, p < .001; β = −0.25, p = .04, respectively) were significantly associated with peak elbow varus torque. During fastballs, pitch velocity was significantly associated with peak elbow varus torque (β = 0.38, p = .002), while release point distance was significantly associated with peak elbow varus torque during change-ups (β = −0.33, p = .015). Youth pitchers with longer strides and less lateral pelvic tilt demonstrated greater elbow torque regardless of pitch type, while the association of ball velocity and release point to elbow varus torque was dependent on pitch type.

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David R. Howell, Thomas A. Buckley, Brant Berkstresser, Francis Wang, and William P. Meehan III

The purpose of this study was to identify the rate of abnormal single-task and dual-task gait performance following concussion compared to uninjured controls using previously established normative reference values. The authors examined athletes with a concussion (n = 54; mean age = 20.3 [1.1] y, 46% female, tested 2.9 [1.5] d postinjury), and healthy controls were tested during their preseason baseline examination (n = 60; mean age = 18.9 [0.7] y, 37% female). Participants completed an instrumented single-/dual-task gait evaluation. Outcome variables included average walking speed, cadence, and step length. A significantly greater number of those with concussion walked with abnormal dual-task gait speed compared with the control group (56% vs 30%, P = .01). After adjusting for potential confounding variables (age, concussion history, symptom severity, and sleep), concussion was associated with lower dual-task gait speed (β = −0.150; 95% confidence interval [CI] = −0.252 to −0.047), cadence (β = −8.179; 95% CI = −14.49 to −1.871), and stride length (β = −0.109; 95% CI = −0.204 to −0.014). Although group analyses indicated that those with a concussion performed worse on single-task and dual-task gait compared with controls, a higher rate of abnormal gait was detected for the concussion group compared with the control group for dual-task gait speed only. Dual-task gait speed, therefore, may be considered as a measure to compare against normative values to detect postconcussion impairments.

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David R. Howell, Corrine N. Seehusen, Mathew J. Wingerson, Julie C. Wilson, Robert C. Lynall, and Vipul Lugade

Our purpose was to investigate the reliability and minimal detectable change characteristics of a smartphone-based assessment of single- and dual-task gait and cognitive performance. Uninjured adolescent athletes (n = 17; mean age = 16.6, SD = 1.3 y; 47% female) completed assessments initially and again 4 weeks later. The authors collected data via an automated smartphone-based application while participants completed a series of tasks under (1) single-task cognitive, (2) single-task gait, and (3) dual-task cognitive-gait conditions. The cognitive task was a series of continuous auditory Stroop cues. Average gait speed was consistent between testing sessions in single-task (0.98, SD = 0.21 vs 0.96, SD = 0.19 m/s; P = .60; r = .89) and dual-task (0.92, SD = 0.22 vs 0.89, SD = 0.22 m/s; P = .37; r = .88) conditions. Response accuracy was moderately consistent between assessments in single-task standing (82.3% accurate, SD = 17.9% vs 84.6% accurate, SD = 20.1%; P = .64; r = .52) and dual-task gait (89.4% accurate, SD = 15.9% vs 85.8% accurate, SD = 20.2%; P = .23; r = .81) conditions. Our results indicate automated motor-cognitive dual-task outcomes obtained within a smartphone-based assessment are consistent across a 1-month period. Further research is required to understand how this assessment performs in the setting of sport-related concussion. Given the relative reliability of values obtained, a smartphone-based evaluation may be considered for use to evaluate changes across time among adolescents, postconcussion.

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David R. Howell, Jessie R. Oldham, Melissa DiFabio, Srikant Vallabhajosula, Eric E. Hall, Caroline J. Ketcham, William P. Meehan III, and Thomas A. Buckley

Gait impairments have been documented following sport-related concussion. Whether preexisting gait pattern differences exist among athletes who participate in different sport classifications, however, remains unclear. Dual-task gait examinations probe the simultaneous performance of everyday tasks (ie, walking and thinking), and can quantify gait performance using inertial sensors. The purpose of this study was to compare the single-task and dual-task gait performance of collision/contact and noncontact athletes. A group of collegiate athletes (n = 265) were tested before their season at 3 institutions (mean age= 19.1 ± 1.1 years). All participants stood still (single-task standing) and walked while simultaneously completing a cognitive test (dual-task gait), and completed walking trials without the cognitive test (single-task gait). Spatial-temporal gait parameters were compared between collision/contact and noncontact athletes using MANCOVAs; cognitive task performance was compared using ANCOVAs. No significant single-task or dual-task gait differences were found between collision/contact and noncontact athletes. Noncontact athletes demonstrated higher cognitive task accuracy during single-task standing (P = .001) and dual-task gait conditions (P = .02) than collision/contact athletes. These data demonstrate the utility of a dual-task gait assessment outside of a laboratory and suggest that preinjury cognitive task performance during dual-tasks may differ between athletes of different sport classifications.