Clinical Scenario: Hamstring strains are common athletic injuries, with a high-recurrence rate (34%). Recently, platelet-rich plasma (PRP) injections have gained popularity as a potential treatment option to accelerate healing of hamstring injury. Focused Clinical Question: Does the combination of PRP injection and rehabilitation decrease recovery time of acute hamstring injury as compared to rehabilitation alone in college athletes? Summary of Key Findings: A literature search resulted in 3 randomized controlled trials. One study showed benefits in various outcome measures with PRP, compared to rehabilitation alone, while 2 showed no benefits. One study reported improved pain, ultrasonography regenerative indications, and recovery time with PRP injection following acute hamstring injury; however, larger studies have shown no benefits. The literature demonstrates conflicting evidence regarding benefits of PRP injections in hamstring injuries. Clinical Bottom Line: At this time, PRP injections cannot be recommended as having value for hamstring injuries, compared to rehabilitation alone. Strength of Recommendation: Due to inconsistent or limited quality patient-oriented evidence in existing literature, the strength of this recommendation is grade B, based on the strength of recommendation taxonomy.
Mary Lynn Manduca and Stephen J. Straub
Derwin K. C. Chan, Vanessa Lentillon-Kaestner, James A. Dimmock, Robert J. Donovan, David A. Keatley, Sarah J. Hardcastle and Martin S. Hagger
We applied the strength-energy model of self-control to understand the relationship between self-control and young athletes’ behavioral responses to taking illegal performance-enhancing substances, or “doping.” Measures of trait self-control, attitude and intention toward doping, intention toward, and adherence to, doping-avoidant behaviors, and the prevention of unintended doping behaviors were administered to 410 young Australian athletes. Participants also completed a “lollipop” decision-making protocol that simulated avoidance of unintended doping. Hierarchical linear multiple regression analyses revealed that self-control was negatively associated with doping attitude and intention, and positively associated with the intention and adherence to doping-avoidant behaviors, and refusal to take or eat the unfamiliar candy offered in the “lollipop” protocol. Consistent with the strength-energy model, athletes with low self-control were more likely to have heightened attitude and intention toward doping, and reduced intention, behavioral adherence, and awareness of doping avoidance.
Gil Rodas, Lourdes Osaba, David Arteta, Ricard Pruna, Dolors Fernández and Alejandro Lucia
Purpose: The authors investigated the association between risk of tendinopathies and genetic markers in professional team sports. Methods: The authors studied 363 (mean [SD]; 25  y, 89% male) elite players (soccer, futsal, basketball, handball, and roller hockey) from a top-level European team (FC Barcelona, Spain). Of 363, 55% (cases) had experienced 1+ episodes of tendinopathy during 2008–2018 and 45% (controls) remained injury free. The authors first examined the association between single-nucleotide polymorphisms (SNPs) and tendinopathy risk in a hypothesis-free case-control genome-wide association study (495,837 SNPs) with additional target analysis of 58 SNPs that are potential candidates to influence tendinopathy risk based on the literature. Thereafter, the authors augmented the SNP set by performing synthetic variant imputation (1,419,369 SNPs) and then used machine learning-based multivariate modeling (support vector machine and random forest) to build a reliable predictive model. Results: Suggestive association (P < 10−5) was found for rs11154027 (gap junction alpha 1), rs4362400 (vesicle amine transport 1-like), and rs10263021 (contactin-associated protein-like 2). Carriage of 1+ variant alleles for rs11154027 (odds ratio = 2.11; 95% confidence interval, 1.07–4.19, P = 1.01 × 10−6) or rs4362400 (odds ratio = 1.98; 95% confidence interval, 1.05–3.73, P = 9.6 × 10−6) was associated with a higher risk of tendinopathy, whereas an opposite effect was found for rs10263021 (odds ratio = 0.42; 95% confidence interval, 0.20–0.91], P = 4.5 × 10−6). In the modeling approach, one of the most robust SNPs was rs10477683 in the fibrillin 2 gene encoding fibrillin 2, a component of connective tissue microfibrils involved in elastic fiber assembly. Conclusions: The authors have identified previously undescribed genetic predictors of tendinopathy in elite team sports athletes, notably rs11154027, rs4362400, and rs10263021.
Jeanne F. Nichols, Mitchell J. Rauh, Michelle T. Barrack, Hava-Shoshana Barkai and Yael Pernick
The authors’ purpose was to determine the prevalence and compare associations of disordered eating (DE) and menstrual irregularity (MI) among high school athletes. The Eating Disorder Examination Questionnaire (EDE-Q) and a menstrual-history questionnaire were administered to 423 athletes (15.7 ± 1.2 y, 61.2 ± 10.2 kg) categorized as lean build (LB; n = 146) or nonlean build (NLB; n = 277). Among all athletes, 20.0% met the criteria for DE and 20.1% for MI. Although the prevalence of MI was higher in LB (26.7%) than NLB (16.6%) athletes (P = 0.01), no differences were found for DE. For both sport types, oligo/amenorrheic athletes consistently reported higher EDE-Q scores than eumenorrheic athletes (P < 0.05). Athletes with DE were over 2 times as likely (OR = 2.3, 95%CI: 1.3, 4.2) to report oligo/amenorrhea than athletes without DE. These data establish an association between DE and MI among high school athletes and indicate that LB athletes have more MI but not DE than NLB athletes.
Julio Cezar Q. Machado, Caroline M.O. Volpe, Leonardo S. Vasconcellos and José A. Nogueira-Machado
Background: Neutrophil gelatinase-associated lipocalin (NGAL) is a glycoprotein released during early phases of a postischemic kidney in response to kidney injury, inflammation, and oxidative stress. It can be detected in urine after 2 hours of an ischemic event. The aim was to measure and to correlate the level of urine NGAL (uNGAL) with urea, creatinine, and glomerular filtration rate (GFR) of endurance cycling athletes (n = 19) and physically active individuals (control, n = 17). Methods: Quantification of urea and creatinine were performed by dry chemical method, and GFR was calculated using the modification of diet in renal disease formula, according to Brazilian Society of Nephrology. uNGAL analyses were performed by enzyme linked immunoabsorbent assay. Analyses were performed 48 hours after exercises. Results: uNGAL (in ng/mL) levels, expressed as median, minimum, and maximum, in cyclist group, 387.7 (109.7–1691.0), was significantly higher than that observed in control (physically active) group, 141.5 (4.8–657.0), (P < .05). No significant correlations were observed between uNGAL and creatinine, urea, or GFR (P > .05). Conclusions: Results have pointed to increased uNGAL levels in endurance cycling athletes. Increase of uNGAL in absence of clinical signs or alterations in creatinine, urea, or GFR might suggest that there is metabolic adaptation to endurance exercise, or possibly predisposition to acute kidney injury over time.
Clinical Scenario: Ice hockey and soccer are both dynamic sports that involve continuous, unpredictable play. These athletes consistently demonstrate higher rates of groin strains compared with other contact sports. Measuring the hip adductor/abductor ratio has the potential to expose at-risk players, reduce injury rates, and preserve groin health in players with chronic strains. Focused Clinical Question: What is the clinical utility of measuring the hip adductor/abductor ratio for preseason and in-season ice hockey and soccer players? Summary of Key Findings: Three studies, all of which were prospective cohort designs, were included. One study involved assessing preseason strength and flexibility as a risk factor for adductor strains in professional ice hockey players. Another study performed with the same professional hockey team used preseason hip adductor/abductor strength ratios to screen for those players who would benefit from a strengthening intervention aimed at reducing the incidence of adductor strains. The final study, which was performed in elite U17 soccer players, assessed the effectiveness of monthly in-season strength monitoring as a guide to trigger in-season interventions to decrease injury incidence. Clinical Bottom Line: Measuring the hip adductor/abductor strength ratio in hockey and soccer players can be a beneficial preseason and in-season tool to predict future groin strain risk and screen for athletes who might benefit from a strengthening intervention. Strength of Recommendation: Level 3 evidence exists to support monitoring the hip adductor/abductor strength ratio to assess and reduce the risk of adductor strains in ice hockey and soccer players.
Constantine P. Nicolozakes, Daniel K. Schneider, Benjamin D. Roewer, James R. Borchers and Timothy E. Hewett
Context: The functional movement screen (FMS™) is used to identify movement asymmetries and deficiencies. While obesity has been reported to impede movement, the correlation between body mass index (BMI), body fat percentage (BF%), and FMS™ in athletes is unknown. Objective: To determine if there is a relationship between BMI, BF%, and FMS™ scores in a sample of National Collegiate Athletic Association Division I football athletes. Design: Cross-sectional study. Setting: Biodynamics laboratory. Participants: A total of 38 male freshman football players (18.0 [0.7] y, 185.3 [5.5] cm, and 103.9 [20.3] kg). Interventions: Height, weight, and BF% were collected, and subjects underwent the FMS™ conducted by a certified athletic trainer. Main Outcome Measures: The dependent variables were BMI, BF%, composite FMS™ score, and 7 individual FMS™ test scores. Subjects were grouped as normal BMI (BMI < 30 kg/m2) or obese (BMI ≥ 30 kg/m2). A composite FMS™ score of ≤14 and an individual FMS™ score of ≤1 were classified as cutoffs for poor movement performance. Results: A negative correlation between composite FMS™ score and BMI approached significance (P = .07, ρ = .296). A negative correlation between composite FMS™ score and BF% was significant (P = .01, ρ = −.449). There was a significant difference in the number of obese subjects scoring below the composite FMS™ cutoff (χ 2 = 5.179, P = .02) and the individual FMS™ cutoff on the deep squat (χ 2 = 6.341, P = .01), hurdle step (χ 2 = 9.870, P = .002), and in-line lunge (χ 2 = 5.584, P = .02) when compared with normal BMI subjects. Conclusions: Increased BF% and BMI relate to lower composite FMS™ and individual FMS™ test scores, indicating potentially poor movement patterns in larger National Collegiate Athletic Association football athletes. Future research should focus on examining lower extremity–specific FMS™ tasks individually from composite FMS™ scores.
Michael S. Guss, John P. Begly, Austin J. Ramme, David P. Taormina, Michael E. Rettig and John T. Capo
Context: Major League Baseball (MLB) players are at risk of hook of hamate fractures. There is a paucity of data assessing the effect of a hook of hamate fracture on MLB players’ future athletic performance. Objective: To determine if MLB players who sustain hook of hamate fractures demonstrate decreased performance upon return to competition when compared with their performance before injury and that of their control-matched peers. Design: Retrospective case-control design. Setting: Retrospective database study. Participants: 18 MLB players who sustained hook of hamate fractures. Methods: Data for 18 MLB players with hook of hamate fractures incurred over 26 seasons (1989–2014) were obtained from injury reports, press releases, and player profiles (www.mlb.com and www.baseballreference.com). Player age, position, number of years in the league, mechanism of injury, and treatment were recorded. Individual season statistics for the 2 seasons immediately prior to injury and the 2 seasons after injury for the main performance variable—Wins Above Replacement—were obtained. Eighteen controls matched by player position, age, and performance statistics were identified. A performance comparison of the cohorts was performed. Main Outcome Measures: Postinjury performance compared with preinjury performance and matched-controls. Results: Mean age at the time of injury was 25.1 years with a mean of 4.4 seasons of MLB experience prior to injury. All injuries were sustained to their nondominant batting hand. All players underwent operative intervention. There was no significant change in Wins Above Replacement or isolated power when preinjury and postinjury performance were compared. When compared with matched-controls, no significant decline in performance in Wins Above Replacement the first season and second season after injury was found. Conclusion: MLB players sustaining hook of hamate fractures can reasonably expect to return to their preinjury performance levels following operative treatment.
Rochelle Rocha Costa, Adriana Cristine Koch Buttelli, Alexandra Ferreira Vieira, Leandro Coconcelli, Rafael de Lima Magalhães, Rodrigo Sudatti Delevatti and Luiz Fernando Martins Kruel
Background: The aim of this study was to perform a systematic review with meta-analysis and meta-regressions evaluating the effects of isolated strength training (ST), compared with a control group, on total cholesterol (TC), triglycerides (TG), low-density (LDL), high-density lipoprotein (HDL), C-reactive protein (CRP), and adiponectin of adults. Methods: Embase, PubMed, Cochrane, and Scopus data sources were searched up to May 2017. Clinical trials that compared ST with a control group of adults older than 18 years, which evaluated blood TC, TG, LDL, HDL, CRP, or adiponectin as an outcome were included. Random effect was used and the effect size (ES) was calculated by using the standardized mean difference with a 95% confidence interval. Results: ST promotes a reduction in TC (ES: −0.399; P < .001), TG (ES: −0.204; P = .002), LDL (ES: −0.451; P < .001), and CRP (ES: −0.542; P = .01) levels. In addition, ST is associated to an increase in HDL (ES: 0.363; P < .001) and adiponectin concentrations (ES: 1.105; P = .01). Conclusion: ST promotes decreases in TC, TG, LDL, and CRP levels and increases HDL and adiponectin concentrations. Thus, progressive ST could be a potential therapeutic option for improving abnormalities in lipid and inflammatory outcomes in adults.
Jeffrey M. Willardson, Fabio E. Fontana and Eadric Bressel
To compare core muscle activity during resistance exercises performed on stable ground vs. the BOSU Balance Trainer.
Twelve trained men performed the back squat, dead lift, overhead press, and curl lifts. The activity of the rectus abdominis, external oblique abdominis, transversus abdominis/internal oblique abdominis, and erector spinae muscles was assessed. Subjects performed each lift under three separate conditions including standing on stable ground with 50% of a 1-RM, standing on a BOSU Balance Trainer with 50% of a 1-RM, and standing on stable ground with 75% of a 1-RM.
Significant differences were noted between the stable 75% of 1-RM and BOSU 50% of 1-RM conditions for the rectus abdominis during the overhead press and transversus abdominis/internal oblique abdominis during the overhead press and curl (P < .05). Conversely, there were no significant differences between the stable 75% of 1-RM and BOSU 50% of 1-RM conditions for the external obliques and erector spinae across all lifts examined. Furthermore, there were no significant differences between the BOSU 50% of 1-RM and stable 50% of 1-RM conditions across all muscles and lifts examined.
The current study did not demonstrate any advantage in utilizing the BOSU Balance Trainer. Therefore, fitness trainers should be advised that each of the aforementioned lifts can be performed while standing on stable ground without losing the potential core muscle training benefits.