Anterior cruciate ligament (ACL) injury in female athletes is common. Team sport athletes experience more ACL injuries than ballet and modern dancers. Examining biomechanical differences between these two groups may help to explain the discrepancy in ACL injury rates. The purpose of this study was to examine lower extremity kinematic differences between collegiate dancers and National Collegiate Athletic Association Division I soccer athletes during a rebound jump-landing task. Peak hip, knee, and ankle kinematics were collected during a jump-landing task. Results showed more knee flexion and less ankle eversion in the dancers compared to the soccer athletes. Differences in training and strategies used during landing may explain the kinematic differences between groups.

Ankle braces and taping are commonly used to prevent ankle sprains and allow return to play following injury, however, it is unclear how passive restriction of joint motion may effect running gait kinematics and energy expenditure during exercise. The purpose of this study was to determine the effect of different types of ankle supports on lower extremity kinematics and energy expenditure during continuous running. Thirteen healthy physically active adults ran at self-selected speed on the treadmill for 30min in four different ankle support conditions: semi-rigid hinged brace, lace-up brace, tape and control. Three-dimensional lower extremity kinematics and energy expenditure were recorded every five minutes. The semi-rigid hinged brace was most effective in restricting frontal plane ankle motion. The lace-up brace and tape restricted sagittal plane ankle motion, while semi-rigid hinged bracing allowed for normal sagittal plane ankle kinematics. Kinematic changes from all three ankle supports were generally persistent through 25-30min of exercise. Only tape influenced knee kinematics, limiting flexion velocity and flexion-extension excursion. Small but significant increased in energy expenditure was found in tape and semi-rigid hinged brace conditions; however, the increases were not to any practically significant level (<0.5kcal/min).

Subconcussive head impacts do not result in outward signs of neurological dysfunction, however they may have an effect on neurocognitive function. Limited research has indicated that negative changes in neurocognitive function occurs in high school football athletes as a result of one season of football. The purpose of this study was to prospectively evaluate the effects of one season of high school football on neurocognitive test scores. Results revealed a significant group and time interaction effect (p < .001) for the Verbal Memory composite score of the ImPACT test. Further analysis revealed a significant difference in the Verbal Memory score between groups at postseason (p < .01), with the football group scoring lower than the low contact group. It appears that one season of high school football may have a negative effect on the Verbal Memory composite score of the ImPACT test in high school football athletes.

The direct anterior (DA) total hip arthroplasty (THA) is a minimally invasive procedure that accesses the hip joint from the anterior aspect of the hip by retracting instead of incising anterior hip musculature during surgery. During this procedure, little to no damage occurs to the hip abductors and extensors, and as a result is theorized to result in an accelerated return to normal function. PURPOSE: To prospectively investigate gait biomechanics following DA THA to identify the short term recovery and time sequence of return to normal gait. METHODS: Nine participants undergoing DA THA (64.1±9 y, 1.7±0.1 m, 72.5±10.8 kg) and nine control participants (60.7±4.3 y, 1.7±0.1 m, 71.4±5.5 kg), completed walking gait trials prior to and at three and six weeks following DA THA surgery. At each session, gait biomechanics at the hip were collected via three-dimensional motion capture system and force plates. RESULTS: Individual two-way repeated measures ANOVA revealed significant biomechanical differences in walking gait between the DA THA and the control groups at pre-surgery, and at three and six weeks following surgery. At pre operation and three weeks post operation, max hip extension (pre: p<0.001, 10.4±10.3; 3 wk post: p=0.005, 3.9±10.7), hip flexion/extension excursion (pre: p<0.001. -20.1±9.8; 3 wk post: p<0.001, -26.85±7.6), hip abduction/adduction excursion (pre: p=0.001, -2.63±2.0, 3 wk post: p=0.02, -4.65±2.24), hip extension moment (pre: p<0.001, -557.3±309.2, 3 wk post: p<0.001, -677.1±215.0) and hip internal rotation moment (pre: p<0.001, 41.89±27.6, 3 wk post: p<0.001, 54.6±31.1) were all significantly less in the DA THA group than the control group. By six weeks post operation, only hip flexion/extension excursion (p<0.001, -33.5±4.3) and hip abduction/adduction excursion (p=0.01, -3.6±2.1) remained significantly lower in the DA THA group. CONCLUSIONS: Short term analysis following DA THA revealed impairments in walking gait at pre operation, and at three and six weeks post operation. By six weeks post operation however, many improvements were made in walking gait when compared to the previous sessions. It appears that the participants began to return to normal function, but a longer follow-up time may be necessary to determine if these DA THA participants completely return to normal walking gait.

BACKGROUND: The direct anterior (DA) total hip arthroplasty (THA) is a minimally invasive procedure that accesses the hip joint from the anterior aspect of the hip by retracting instead of incising muscles during surgery. The lack of soft tissue damage is thought to result in an accelerated return of strength and function. PURPOSE: The purpose of this study was to identify when participants undergoing DA regained normal strength and function. METHODS: Twenty DA and 14 controls participated in this prospective study. Maximum isometric hip strength was measured in all hip motions using a hand-held dynamometer. Function was assessed using the Timed Up and Go (TUG) test and the Trendelenburg Single-Leg Balance (SLB) test. Data were collected at pre-operation, three and six weeks, and three months post-operation. MAIN RESULTS: At three and six weeks post-operation, all strength values except for hip adduction were significantly lower than the control group. By three months, only hip external rotation remained significantly lower in the DA group (p = 0.04; DA: 0.86 ± 0.54 N/BW, Control: 1.22 ± 0.37 N/BW). At three and six weeks post-operation, all strength values except for hip extension and external rotation were more asymmetrical than the control group. By three months post operation, only hip flexion remained more asymmetrical (p = 0.03, DA: –1.11 ± 2.04, Control: 0.55 ± 2.24). There were significant time effects for Trendelenburg SLB test (p = 0.04) and TUG (p = 0.003), but post hoc testing revealed no further differences. CONCLUSIONS: The results indicate that an emphasis on improving hip flexion and external rotation strength may be valuable in regaining normal strength and function in the DA population.

Context:Shoulder injury in baseball pitchers is a very common problem and has been linked to an imbalance in rotator cuff strength. Recently, the use of functional shoulder strength ratios has become more popular because they more closely resemble the actions of the shoulder during the throwing motion.Objective:To investigate the link between preseason shoulder rotator cuff functional strength ratios and the development of shoulder pain and injury.Design:Prospective research design.Setting:University human performance laboratory.Patients:Fifteen collegiate baseball pitchers participated in this study. At the end of the baseball season, six (19.5 ± 1.8 years, 73.6 ± 2.8 inches, 198.7 ± 19.1 lbs) developed shoulder injury and were placed in the injured group, and nine (21.0 ± 1.7 years, 73.1 ± 2.3 inches, 207.9 ± 28.1 lbs) did not develop injury and were placed in the noninjured group.Interventions:Isokinetic peak torque was collected concentrically and eccentrically for both shoulder internal rotation (IR) and external rotation (ER) at 60°-s−1, 180°-s−1, and 300°-s−1.Main Outcome Measure:The following functional ratios were calculated from the peak torque measures: concentric ER: concentric IR; eccentric ER: eccentric IR; concentric ER: eccentric IR (cocking phase); and eccentric ER: concentric IR (acceleration phase). Analysis was conducted using an analysis of variance comparing the injured and noninjured groups. A secondary analysis was conducted using an analyses of variance on the concentric and eccentric peak torque for shoulder IR and ER between groups.Results:The acceleration phase functional shoulder ratio was significantly higher (p = .019) in the injured group and a concentric IR peak torque (p = .003) was significantly lower in the injured group compared with the noninjured group.conclusion:Increased acceleration phase ratios and decreased concentric IR peak torque may be linked to the development of shoulder injury during a baseball season.

This study examined a modification of the Margaria-Kalamen test for football players. The football stair climb test (FST) protocol used in this study increased the vertical displacement (20 steps, 3.12 m) so that the mean best time for the test was 2.048 +/- 0.267 seconds. Fifty-eight Division I-A football players volunteered to participate (mean +/- SD age = 20.2 +/- 1.8 yr, height = 184.1 +/- 7.7 cm, weight = 102.5 +/- 19.4 kg). Subjects performed 25 trials with 30 to 40 seconds of rest between trials. Test-retest reliability was determined using 34 subjects by way of intraclass correlation coefficients with a value of 0.73 for peak power and SEM of 105.4 W, indicating an acceptable level of reliability. Subjects were divided into 3 groups by position: linemen (Line), skill, and linebackers (LB). Alpha level was p < 0.05. Peak power was 1674.5 +/- 300.8, 1712.6 +/- 251.5, and 1388.6 +/- 210.4 W for the LB, Line, and Skill groups, respectively. Groups were significantly different (p < 0.0001), with the LB and Line found to be more powerful than the Skill group. Peak power continued to increase throughout the 25 trials in the Skill and LB group but plateaued after approximately 17 trials in the Line group. It was concluded that the FST was a reliable test for measuring peak anaerobic power in collegiate football players, which, theoretically, should provide more accurate measures of peak power caused by increased vertical displacement and longer duration, resulting in a decreased influence of cheating strategies during test administration. To achieve maximal power in stair climbing tasks, coaches may need to incorporate a greater number of trials or a more intense warm-up than has been previously reported.

PURPOSE: To investigate metabolic responses of HIV-positive patients receiving Highly Active Antiretroviral Therapy (HAART) participating in the Hawaii AIDS Clinical Research Program's Healthy Heart study. METHODS: Twenty-six subjects volunteered to participate in a continuous graded maximal treadmill test (Balke protocol; age=46±9.3 years; ht=173.2±8.2 cm; wt=78.29±12.74 kg; CD4 count=471±201.1; 88.5% of subjects had undetectable viral loads). Metabolic data were collected using standard open-circuit indirect calorimetry techniques. RESULTS: Twenty-five subjects met at least one standard for documenting maximal effort during graded exercise testing as described by the ACSM. Mean (±SD) metabolic data were as follows: VO2max=37.7±7.0 ml·kg−1·min−1; RER=1.07±0.09; HRmax=171.9±14.3 bpm; lactatepre=0.76±0.41 mmol (n = 14); lactatepost=5.05±1.89 mmol (n = 14); RPE= 17.4±2.6. Maximal oxygen uptake represented a normal distribution (skewness=0.50). These values were achieved on subjects who exercised at a mean of 97.5% of age-predicted HRmax (APHRmax=192-0.007·age2). Despite having met at least one of the five ACSM criteria for maximal effort, 12 subjects produced a maximal RER at or below 1.03 and only three of the 25 subjects with criteria for maximal effort produced a maximal RER at or above 1.15. Of the 13 subjects for whom blood lactatepost was assessed, only one subject exceeded the 8.0 mmol criterion and eight of these subjects failed to exceed a blood lactatepost concentration of 5.0 mmol. Although 96% of subjects met at least one ACSM criterion for maximal effort, 88% did not meet the criterion for maximal effort based on an RER>1.15 and 92% of those tested for blood lactate did not meet maximal effort criterion based on lactatepost>8.0 mmol. Eight subjects demonstrated markedly attenuated RER and/or blood lactatepost (RERmax<1.0 and/or lactatepost<2.0 mmol) responses including the individual demonstrating the highest VO2max (VO2max=52.2 ml·kg−1·min−1; RERmax=0.98; lactatepost=1.98 mmol). CONCLUSIONS: Data presented indicate an attenuated anaerobic metabolic response to maximal exercise in an HIV-positive population undergoing HAART.