Jennifer Sanfilippo

Clinical and Morphological Changes Following 2 Rehabilitation Programs for Acute Hamstring Strain Injuries: A Randomized Clinical Trial

STUDY DESIGN Randomized, double-blind, parallel-group clinical trial. OBJECTIVES To assess differences between a progressive agility and trunk stabilization rehabilitation program and a progressive running and eccentric strengthening rehabilitation program in recovery characteristics following an acute hamstring injury, as measured via physical examination and magnetic resonance imaging (MRI). BACKGROUND Determining the type of rehabilitation program that most effectively promotes muscle and functional recovery is essential to minimize reinjury risk and to optimize athlete performance. METHODS Individuals who sustained a recent hamstring strain injury were randomly assigned to 1 of 2 rehabilitation programs: (1) progressive agility and trunk stabilization or (2) progressive running and eccentric strengthening. MRI and physical examinations were conducted before and after completion of rehabilitation. RESULTS Thirty-one subjects were enrolled, 29 began rehabilitation, and 25 completed rehabilitation. There were few differences in clinical or morphological outcome measures between rehabilitation groups across time, and reinjury rates were low for both rehabilitation groups after return to sport (4 of 29 subjects had reinjuries). Greater craniocaudal length of injury, as measured on MRI before the start of rehabilitation, was positively correlated with longer return-to-sport time. At the time of return to sport, although all subjects showed a near-complete resolution of pain and return of muscle strength, no subject showed complete resolution of injury as assessed on MRI. CONCLUSION The 2 rehabilitation programs employed in this study yielded similar results with respect to hamstring muscle recovery and function at the time of return to sport. Evidence of continuing muscular healing is present after completion of rehabilitation, despite the appearance of normal physical strength and function on clinical examination. LEVEL OF EVIDENCE Therapy, level 1b-.

Hamstring strength and morphology progression after return to sport from injury

PURPOSE Hamstring strain reinjury rates can reach 30% within the initial 2 wk after return to sport (RTS). Incomplete recovery of strength may be a contributing factor. However, relative strength of the injured and unaffected limbs at RTS is currently unknown.The purpose was to characterize hamstring strength and morphology at the time of RTS and 6 months later. METHODS Twenty-five athletes who experienced an acute hamstring strain injury participated after completion of a controlled rehabilitation program. Bilateral isokinetic strength testing and magnetic resonance imaging (MRI) were performed at RTS and 6 months later. Strength (knee flexion peak torque, work, and angle of peak torque) and MRI (muscle and tendon volumes) measures were compared between limbs and over time using repeated-measures ANOVA. RESULTS The injured limb showed a peak torque deficit of 9.6% compared to the uninjured limb at RTS (60°·s, P < 0.001) but not 6 months after. The knee flexion angle of peak torque decreased over time for both limbs (60°·s, P < 0.001). MRI revealed that 20.4% of the muscle cross-sectional area showed signs of edema at RTS with full resolution by the 6-month follow-up. Tendon volume of the injured limb tended to increase over time (P = 0.108), whereas muscle volume decreased between 4% and 5% in both limbs (P < 0.001). CONCLUSIONS Residual edema and deficits in isokinetic knee flexion strength were present at RTS but resolved during the subsequent 6 months. This occurred despite MRI evidence of scar tissue formation (increased tendon volume) and muscle atrophy, suggesting that neuromuscular factors may contribute to the return of strength.

Concussion Increases Odds of Sustaining a Lower Extremity Musculoskeletal Injury After Return to Play Among Collegiate Athletes

Background: Previous studies have identified abnormalities in brain and motor functioning after concussion that persist well beyond observed clinical recovery. Recent work suggests subtle deficits in neurocognition may impair neuromuscular control and thus potentially increase risk of lower extremity musculoskeletal injury after concussion. Purpose: To determine the odds of sustaining an acute lower extremity musculoskeletal injury during the 90-day period after return to play from concussion in a cohort of National Collegiate Athletic Association (NCAA) Division I collegiate athletes. Study Design: Cohort study; Level of evidence, 3. Methods: Included in this study were 87 cases of concussion among 75 athletes (58 men; 17 women) participating in NCAA Division I football, soccer, hockey, softball, basketball, wrestling, or volleyball at a single institution from 2011 to 2014. The 90-day period after return to play for each case of concussion was reviewed for acute noncontact lower extremity musculoskeletal injury. Each 90-day period after return to play was matched to the same 90-day period in up to 3 controls. Control athletes without a history of concussion in the previous year were matched to concussed athletes by sport team/sex, games played, and position. A total of 182 control (136 men; 46 women) 90-day periods were reviewed for acute injury. Conditional logistic regression was used to assess the association between concussion and subsequent risk of acute lower extremity musculoskeletal injury. Results: The incidence of acute lower extremity musculoskeletal injury was higher among recently concussed athletes (15/87; 17%) compared with matched controls (17/182; 9%). The odds of sustaining an acute lower extremity musculoskeletal injury during the 90-day period after return to play were 2.48 times higher in concussed athletes than controls during the same 90-day period (odds ratio, 2.48; 95% CI, 1.04-5.91; P = .04). Conclusion: Concussed athletes have increased odds of sustaining an acute lower extremity musculoskeletal injury after return to play than their nonconcussed teammates. The study results suggest further investigation of neurocognitive and motor control deficits may be warranted beyond the acute injury phase to decrease risk for subsequent injury.

Lean mass asymmetry influences force and power asymmetry during jumping in collegiate athletes.

Abstract Bell, DR, Sanfilippo, JL, Binkley, N, and Heiderscheit, BC. Lean mass asymmetry influences force and power asymmetry during jumping in collegiate athletes. J Strength Cond Res 28(4): 884–891, 2014—The purpose of this investigation was to (a) examine how asymmetry in lower extremity lean mass influenced force and power asymmetry during jumping, (b) determine how power and force asymmetry affected jump height, and (c) report normative values in collegiate athletes. Force and power were assessed from each limb using bilateral force plates during a countermovement jump in 167 division 1 athletes (mass = 85.7 ± 20.3 kg, age = 20.0 ± 1.2 years; 103 men and 64 women). Lean mass of the pelvis, thigh, and shank was assessed using dual-energy x-ray absorptiometry. Percent asymmetry was calculated for lean mass at each region (pelvis, thigh, and shank) as well as force and power. Forward stepwise regressions were performed to determine the influence of lean mass asymmetry on force and power asymmetry. Thigh and shank lean mass asymmetry explained 20% of the variance in force asymmetry (R2 = 0.20, p < 0.001), whereas lean mass asymmetry of the pelvis, thigh, and shank explained 25% of the variance in power asymmetry (R2 = 0.25, p < 0.001). Jump height was compared across level of force and power asymmetry (p > 0.05) and greater than 10% asymmetry in power tended to decrease the performance (effect size >1.0). Ninety-five percent of this population (2.5th to 97.5th percentile) displayed force asymmetry between −11.8 and 16.8% and a power asymmetry between −9.9 and 11.5%. A small percentage (<4%) of these athletes displayed more than 15% asymmetry between limbs. These results demonstrate that lean mass asymmetry in the lower extremity is at least partially responsible for asymmetries in force and power. However, a large percentage remains unexplained by lean mass asymmetry.

Dual-Energy X-Ray Absorptiometry Measured Regional Body Composition Least Significant Change: Effect of Region of Interest and Gender in Athletes

Dual-energy X-ray absorptiometry (DXA) is widely used to evaluate body composition in athletes. Knowledge of measurement precision is essential for monitoring body composition changes over time. This study begins characterizing DXA body composition precision in 60 (30 males and 30 females) Division 1 athletes focusing on gender, regional, and tissue type differences. Two total body scans with repositioning between were performed on the same day. Least significant change (LSC) for the root-mean-square deviation (LSCRMSD) and the percent coefficient of variation (LSC%CV) for total, lean, and fat mass was calculated for 6 regions of interest. The effect of gender, region, tissue type, and mass on the standard deviation (SD) and percent coefficient of variation (%CV) between the 2 scans was evaluated using repeated measures regression analysis. Statistically significant effects of gender, region, tissue type, and mass on SD and %CV were noted. To generalize, a nonlinear positive relationship between LSCRMSD and mass and a nonlinear negative relationship between LSC%CV and mass were observed. In conclusion, DXA body composition LSC varies among genders, regions, tissues, and mass. As such, when evaluating serial body composition in athletes, especially if assessing regional change, knowledge of precision in individuals of similar body size and gender to the population of interest is needed.

High School Sport Specialization Patterns of Current Division I Athletes

Background: Sport specialization is a strategy to acquire superior sport performance in 1 sport but is associated with increased injury risk. Currently, the degree of high school specialization among Division I athletes is unknown. Hypothesis: College athletes will display increased rates of specialization as they progress through their high school careers. Study Design: Descriptive epidemiological study. Level of Evidence: Level 4. Methods: Three hundred forty-three athletes (115 female) representing 9 sports from a Midwest Division I University completed a previously utilized sport specialization questionnaire regarding sport participation patterns for each grade of high school. McNemar and chi-square tests were used to investigate associations of grade, sport, and sex with prevalence of sport specialization category (low, moderate, high) (a priori P ≤ 0.05). Results: Specialization increased throughout high school, with 16.9% (n = 58) and 41.1% (n = 141) of athletes highly specialized in 9th and 12th grades, respectively. Football athletes were less likely to be highly specialized than nonfootball athletes for each year of high school (P < 0.001). There was no difference in degree of specialization between sexes at any grade level (P > 0.23). Conclusion: The majority of Division I athletes were not classified as highly specialized throughout high school, but the prevalence of high specialization increased as athletes progressed through high school. Nonfootball athletes were more likely to be highly specialized than football athletes at each grade level. Clinical Relevance: Most athletes who are recruited to participate in collegiate athletics will eventually specialize in their sport, but it does not appear that early specialization is necessary to become a Division I athlete. Athletes should be counseled regarding safe participation in sport during high school to minimize injury and maximize performance.

Star Excursion Balance Test Performance Varies by Sport in Healthy Division I Collegiate Athletes

STUDY DESIGN Cross-sectional. OBJECTIVES To describe performance and asymmetry on the Star Excursion Balance Test (SEBT) by sex and sport, and to determine if differences exist within a collegiate athlete population. BACKGROUND Performance on the SEBT may differ between sexes and levels of competition, though the results of previous studies have been inconsistent. Investigation of performance and asymmetry differences between sports is limited. Sex- and sport-specific reference values likely need to be determined to best assess SEBT performance. METHODS Performance on the SEBT was retrospectively reviewed in 393 healthy National Collegiate Athletic Association Division I collegiate athletes from 8 sports. Means, standard deviations, and 95% confidence intervals were calculated for all variables. Normalized reach distance (percent limb length) and asymmetry between limbs were compared for the anterior (ANT), posterolateral (PL), and posteromedial (PM) directions and for the composite (COMP) score using a 2-way analysis of variance (ANOVA) of sex by sport, and a 1-way ANOVA to separately compare sports within each sex. RESULTS Average normalized reach distance ranged from 62% to 69%, 84% to 97%, and 99% to 113% in the ANT, PL, and PM directions, respectively, and from 82% to 92% in the COMP score. Normalized asymmetry ranged from 3% to 4%, 5% to 8%, and 5% to 6% in the ANT, PL, and PM directions, respectively. A significant sex-by-sport interaction (P = .039) was observed in the ANT direction, with a sex effect for soccer players (P<.001; men less than women). Significant differences were observed in the PL and PM directions and in the COMP score among womens teams, with womens ice hockey players reaching the farthest (COMP, 90.0%). Among mens teams, significant differences were observed in all directions and in the COMP score. Mens ice hockey players (COMP, 91.9%) and wrestlers achieved the farthest distances (COMP, 88.8%). CONCLUSION Performance on the SEBT varies by team, with a difference between sexes also present for soccer. Performance on the SEBT and potential injury risk should be interpreted within the context of the athletes sport.

A DXA Whole Body Composition Cross-Calibration Experience: Evaluation With Humans, Spine, and Whole Body Phantoms

New densitometer installation requires cross-calibration for accurate longitudinal assessment. When replacing a unit with the same model, the International Society for Clinical Densitometry recommends cross-calibrating by scanning phantoms 10 times on each instrument and states that spine bone mineral density (BMD) should be within 1%, whereas total body lean, fat, and %fat mass should be within 2% of the prior instrument. However, there is limited validation that these recommendations provide adequate total body cross-calibration. Here, we report a total body cross-calibration experience with phantoms and humans. Cross-calibration between an existing and new Lunar iDXA was performed using 3 encapsulated spine phantoms (GE [GE Lunar, Madison, WI], BioClinica [BioClinica Inc, Princeton, NJ], and Hologic [Hologic Inc, Bedford, MA]), 1 total body composition phantom (BioClinica), and 30 human volunteers. Thirty scans of each phantom and a total body scan of human volunteers were obtained on each instrument. All spine phantom BMD means were similar (within 1%; <-0.010 g/cm2 bias) between the existing and new dual-energy X-ray absorptiometry unit. The BioClinica body composition phantom (BBCP) BMD and bone mineral content (BMC) values were within 2% with biases of 0.005 g/cm2 and -3.4 g. However, lean and fat mass and %fat differed by 4.6%-7.7% with biases of +463 g, -496 g, and -2.8%, respectively. In vivo comparison supported BBCP data; BMD and BMC were within ∼2%, but lean and fat mass and %fat differed from 1.6% to 4.9% with biases of +833 g, -860 g, and -1.1%. As all body composition comparisons exceeded the recommended 2%, the new densitometer was recalibrated. After recalibration, in vivo bias was lower (<0.05%) for lean and fat; -23 and -5 g, respectively. Similarly, BBCP lean and fat agreement improved. In conclusion, the BBCP behaves similarly, but not identical, to human in vivo measurements for densitometer cross-calibration. Spine phantoms, despite good BMD and BMC agreement, did not detect substantial lean and fat differences observed using BBCP and in vivo assessments. Consequently, spine phantoms are inadequate for dual-energy X-ray absorptiometry whole body composition cross-calibration.

Star Excursion Balance Test Anterior Asymmetry Is Associated With Injury Status in Division I Collegiate Athletes

STUDY DESIGN: Retrospective cohort. BACKGROUND: Star Excursion Balance Test (SEBT) performance differs by sport in healthy collegiate athletes, and lower extremity injury rates also vary by sport, sex, and athletic exposure. The relationship between SEBT performance and injury risk has not been evaluated with consideration of these additional variables, which may be necessary to fully describe the relationship between SEBT performance and injury risk. OBJECTIVES: To assess the association between preseason SEBT performance and noncontact injury occurrence to the knee or ankle in Division I collegiate athletes when controlling for sport, sex, and athletic exposure. METHODS: Star Excursion Balance Test performance, starting status, and injury status were reviewed retrospectively in National Collegiate Athletic Association Division I collegiate athletes from a single institution. A total of 147 athletes were healthy at the time of preseason SEBT testing and either remained healthy (n = 118) or sustained a noncontact injury to the knee or ankle (n = 29) during their sports subsequent competitive season. Side‐to‐side asymmetries were calculated in each direction as the absolute difference in reach distance between limbs. Star Excursion Balance Test reach distances and asymmetries were compared between groups using multivariable regression, controlling for sport, sex, and athletic exposure (starter, nonstarter). Receiver operating characteristic curves were used to determine optimal sensitivity and specificity for significant models. RESULTS: When controlling for sport, sex, and athletic exposure, SEBT side‐to‐side asymmetry in the anterior direction, expressed as an absolute or normalized to limb length, discriminated between injured and noninjured athletes (area under the curve greater than 0.82). CONCLUSION: Assessing side‐to‐side reach asymmetry in the anterior direction of the SEBT may assist in identifying collegiate athletes who are at risk for sustaining noncontact injuries to the knee or ankle. LEVEL OF EVIDENCE: Prognosis, level 2b.

Preseason Aerobic Capacity Is an Independent Predictor of In-Season Injury in Collegiate Soccer Players.

Purpose: To determine whether preseason aerobic capacity is independently associated with in-season injury among collegiate soccer players. Design: Prospective cohort study. Setting: University athletic department. Participants: Forty-three NCAA Division I soccer athletes (male = 23). Independent Variables: Gender and preseason lean body mass (LBM), body fat percentage (BF%), and maximal aerobic capacity (V[Combining Dot Above]O2max). Main Outcome Measures: In-season injuries were recorded during the season, and body composition and fitness variables were compared between injured and uninjured players. Multivariate regression models were developed to predict injury during the entire season and during the first 4 weeks of the season. Results: Thirty-five injuries among 25 players were recorded during the season. Players injured at any point during the season had lower V[Combining Dot Above]O2max (57.7 vs 63.4 mL·kg−1·min−1, P = 0.014) and Tmax (15.8 vs 17.2 minutes, P = 0.035), compared with uninjured players, but no differences were noted in age, gender, LBM, or BF%. Players injured during the first 4 weeks of the season had lower LBM (49.7 vs 56.0 kg, P = 0.038) and Tmax (15.1 vs 16.7 minutes, P = 0.043) than uninjured players. For injuries occurring throughout the entire season, V[Combining Dot Above]O2max was an independent predictor of injury (P = 0.043), whereas gender, LBM, and BF% were not. During the first 4 weeks of the season, V[Combining Dot Above]O2max (P = 0.035) and LBM (P = 0.049) were related to injury, whereas gender and BF% were not. Conclusions: Aerobic fitness is an independent predictor of in-season injury. Early-season injuries are related to aerobic fitness and LBM. Clinical Relevance: Efforts to increase aerobic capacity and LBM among soccer players in the off-season may help reduce in-season injury.