Search Results

Studies investigating the effect of targeting on gait have focused on the analysis of ground reaction force (GRF) within the time domain. Analysis within the frequency domain may be a more sensitive method for evaluating variations in GRF. The aim of the present study was to investigate the effect of visual targeting on GRF analyzed within the frequency domain. A within-subject repeated-measures design was used to measure the mediolateral, vertical, and antero-posterior components of the GRF of 11 healthy volunteers while walking at their own pace over a paper-covered walkway. A 30 × 24-cm target area was superimposed over a hidden Kistler force plate mounted at the midpoint of the walkway. GRF were recorded with and without the target and were analyzed within the frequency domain. Although visually guided foot placement has previously been undetected by traditional time-domain measures, targeting was found to significantly increase the frequency content of both the mediolateral (t₁₀ = -4.07, p < 0.05) and antero-posterior (t₁₀ = -2.52, p < 0.05) components of GRF. Consequently, it appears that frequency analysis is a more sensitive analytic technique for evaluating GRF. These findings have methodological implications for research in which GRF is used to characterize and assess anomalies in gait patterns.

Purpose: The purpose of this investigation was to examine the weight management (WM) behaviors of collegiate wrestlers after the implementation of the NCAA’s new weight control rules. Methods: In the fall of 1999, a survey was distributed to 47 college wrestling teams stratified by collegiate division (i.e., I, II, III) and competitive quality. Forty-three teams returned surveys for a total of 741 responses. Comparisons were made using the collegiate division, weight class, and the wrestler’s competitive winning percentage. Results: The most weight lost during the season was 5.3 kg ± 2.8 kg (mean ± SD) or 6.9% ± 4.7% of the wrestler’s weight; weekly weight lost averaged 2.9 kg ± 1.3 kg or 4.3% ± 2.3% of the wrestler’s weight; post-season, the average wrestler regained 5.5 kg ± 3.6 kg or 8.6% ± 5.4% of their weight. Coaches and fellow wrestlers were the primary influence on weight loss methods; however, 40.2% indicated that the new NCAA rules deterred extreme weight loss behaviors. The primary methods of weight loss reported were gradual dieting (79.4%) and increased exercise (75.2%). However, 54.8% fasted, 27.6% used saunas, and 26.7% used rubber/ plastic suits at least once a month. Cathartics and vomiting were seldom used to lose weight, and only 5 met three or more of the criteria for bulimia nervosa. WM behaviors were more extreme among freshmen, lighter weight classes, and Division II wrestlers. Compared to previous surveys of high school wrestlers, this cohort of wrestlers reported more extreme WM behaviors. However, compared to college wrestlers in the 1980s, weight loss behaviors were less extreme. Conclusions: The WM practices of college wrestlers appeared to have improved compared to wrestlers sampled previously. Forty percent of the wrestlers were influenced by the new NCAA rules and curbed their weight loss practices. Education is still needed, as some wrestlers are still engaging in dangerous WM methods.

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.

Generating consistent maximum ball velocity is an important factor for a baseball pitcher’s success. While previous investigations have focused on the role of the upper and lower extremities, little attention has been given to the trunk. In this study it was hypothesized that variations in pelvis and upper torso kinematics within individual pitchers would be significantly associated with variations in pitched ball velocity. Nineteen elite baseball pitchers were analyzed using 3-D high-speed motion analysis. For inclusion in this study, each pitcher demonstrated a variation in ball velocity of at least 1.8 m/s (range: 1.8–3.5 m/s) during his 10 fastball pitch trials. A mixed-model analysis was used to determine the relationship between 12 pelvis and upper torso kinematic variables and pitched ball velocity. Results indicated that five variables were associated with variations in ball velocity within individual pitchers: pelvis orientation at maximum external rotation of the throwing shoulder (p = .026), pelvis orientation at ball release (p = .044), upper torso orientation at maximum external rotation of the throwing shoulder (p = .007), average pelvis velocity during arm cocking (p = .024), and average upper torso velocity during arm acceleration (p = .035). As ball velocity increased, pitchers showed an increase in pelvis orientation and upper torso orientation at the instant of maximal external rotation of the throwing shoulder. In addition, average pelvis velocity during arm cocking and average upper torso velocity during arm acceleration increased as ball velocity increased. From a practical perspective, the athlete should be coached to strive for proper trunk rotation during arm cocking as well as strength and flexibility in order to generate angular velocity within the trunk for maximum ball velocity.

Purpose: This study examined performance and physiological adaptations following 3 weeks of repeated-sprint training (RST) with blood-flow restriction (BFR) or without (non-BFR). Methods: Twenty-six semiprofessional and amateur adult male team-sport players were assessed for repeated-sprint ability, anaerobic capacity, leg lean mass, neuromuscular function, and maximal aerobic capacity before and after RST. Participants completed 9 cycling RST sessions (3 sets of 5–7 × 5-s sprints, 25-s passive recovery, 3-min rest) over a 3-week period with BFR or non-BFR. Results: During RST sessions, the BFR group demonstrated lower mean power output compared with non-BFR (−14.5%; g = 1.48; P = .001). Significant improvements (P < .05) in mean and peak power output during repeated-sprint ability (+4.1%; g = 0.42, and + 2.2%; g = 0.25, respectively) and anaerobic capacity (+4.8%; g = 0.47, and + 4.7%; g = 0.32, respectively) tests, leg lean mass (+2.0%; g = 0.16), and peak aerobic power (+3.3%; g = 0.25) were observed from pretesting to posttesting without any between-groups differences. No significant changes (P > .05) were observed for maximal isometric voluntary contraction and maximal aerobic capacity. Peak rate of force development decreased (P = .003) in both groups following RST (−14.6%; g = 0.65), without any between-groups differences. Conclusions: Repeated-sprint ability, anaerobic capacity, leg lean mass, and peak aerobic power improved following 3 weeks of RST; however, the addition of BFR did not further enhance adaptations. Interestingly, comparable improvements were achieved between groups despite lower external loads experienced during RST sessions with BFR.

Context: A limiting factor for reducing anterior cruciate ligament injury risk is ensuring that the movement adaptions made during the prevention program transfer to sport-specific activity. Virtual reality provides a mechanism to assess transferability, and neuroimaging provides a means to assay the neural processes allowing for such skill transfer. Objective: To determine the neural mechanisms for injury risk–reducing biomechanics transfer to sport after anterior cruciate ligament injury prevention training. Design: Cohort study. Setting: Research laboratory. Participants: Four healthy high school soccer athletes. Interventions: Participants completed augmented neuromuscular training utilizing real-time visual feedback. An unloaded knee extension task and a loaded leg press task were completed with neuroimaging before and after training. A virtual reality soccer-specific landing task was also competed following training to assess transfer of movement mechanics. Main Outcome Measures: Landing mechanics during the virtual reality soccer task and blood oxygen level–dependent signal change during neuroimaging. Results: Increased motor planning, sensory and visual region activity during unloaded knee extension and decreased motor cortex activity during loaded leg press were highly correlated with improvements in landing mechanics (decreased hip adduction and knee rotation). Conclusion: Changes in brain activity may underlie adaptation and transfer of injury risk–reducing movement mechanics to sport activity. Clinicians may be able to target these specific brain processes with adjunctive therapy to facilitate intervention improvements transferring to sport.