Assessing the Relationship Between External Workloads and Noncontact Injuries During Summer Conditioning and Preseason Practice in National Collegiate Athletic Association Division 1 Football Players.

ABSTRACT: Burghardt, WP, Pfeiffer, KA, and Kuenze, C. Assessing the relationship between external workloads and noncontact injuries during summer conditioning and preseason practice in National Collegiate Athletic Association Division 1 football players. J Strength Cond Res 37(4): 816-822, 2023-The purpose of this study was to prospectively investigate the relationship between noncontact injuries and workload in collegiate football during summer conditioning and preseason training. Workload and noncontact injury data were collected over the summer conditioning and preseason practice periods for a Division 1 National Collegiate Athletic Association football team ( n = 34). Seven- and 21-day exponentially weighted moving averages (EWMA) were calculated daily for each athlete. The acute:chronic ratio (A:C ratio) of these 2 measures was also calculated daily. Injury rates for noncontact injuries were calculated for both periods. Continuous variable modeling (panel logistic regression and restricted cubic spline) was used to assess the relationship of EWMA A:C ratio and noncontact injury using a 3-day lag period. Athletic exposures (AEs) were defined as individual sport training, practice, or competition sessions. Nine injuries were observed (6.97/1,000 AEs), with 4 injuries resulting in lost time (3.09/1,000 AEs). The mean EWMA A:C ratio was 0.92 ± 0.41 (95% confidence interval: 0.03-2.09). Both the panel logistic regression and the restricted cubic spline models showed a significant relationship between EWMA A:C ratio and noncontact injuries. However, the odds ratio (14.16) in the logistic regression had a very large standard error (14.51) and a wide 95% confidence interval (1.90-105.49). The restricted cubic spline model had a pseudo R2 of 0.136. Injury occurrence at given EWMA ratio values was lower than reported in previous research. Although both continuous models demonstrated a significant relationship between the EWMA A:C ratio and subsequent noncontact injuries over the next 3 days, neither model had sufficient goodness of fit to warrant adoption at this time.

Preseason to Postseason Changes on the BTrackS Force Plate in a Sample of College Athletes.

CONTEXT: Balance testing is a vital component in the evaluation and management of sport-related concussion. Few studies have examined the use of objective, low-cost, force-plate balance systems and changes in balance after a competitive season. OBJECTIVE: To examine the extent of preseason versus postseason static balance changes using the Balance Tracking System (BTrackS) force plate in college athletes. DESIGN: Pretest, posttest design. SETTING: Athletic training facility. PARTICIPANTS: A total of 47 healthy, Division-I student-athletes (33 males and 14 females; age 18.4 [0.5] y, height 71.8 [10.8] cm, weight 85.6 [21.7] kg) participated in this study. MAIN OUTCOME MEASURES: Total center of pressure path length was measured preseason and postseason using the BTrackS force plate. A Wilcoxon signed-rank test was conducted to examine preseason and postseason changes. SEM and minimal detectable change were also calculated. RESULTS: There was a significant difference in center of pressure path length differed between preseason (24.6 [6.8] cm) and postseason (22.7 [5.4] cm) intervals (P = .03), with an SEM of 3.8 cm and minimal detectable change of 10.5 cm. CONCLUSIONS: Significant improvements occurred for center of pressure path length after a competitive season, when assessed using the BTrackS in a sample of college athletes. Further research is warranted to determine the effectiveness of the BTrackS as a reliable, low-cost alternative to force-plate balance systems. In addition, clinicians may need to update baseline balance assessments more frequently to account for improvements.

MRI-Based Assessment of Lower-Extremity Muscle Volumes in Patients Before and After ACL Reconstruction.

CONTEXT: Study of muscle volumes in patients after anterior cruciate ligament (ACL) injury and reconstruction (ACL-R) is largely limited to cross-sectional assessment of the thigh musculature, which may inadequately describe posttraumatic and postsurgical muscle function. No studies have prospectively examined the influence of ACL injury and reconstruction on lower-extremity muscle volumes. OBJECTIVE: Assess magnetic resonance imaging-derived lower-extremity muscle volumes, and quantify quadriceps strength and activation in patients following ACL injury and reconstruction. DESIGN: Prospective case series. SETTING: Research laboratory and magnetic resonance imaging facility. Patients (or Other Participants): Four patients (2 men and 2 women; age = 27.4 (7.4) y, height = 169.2 (8.1) cm, and mass = 74.3 (18.5) kg) scheduled for ACL-R. INTERVENTION(S): Thirty-five muscle volumes were obtained from a bilateral lower-extremity magnetic resonance imaging before and after ACL-R. MAIN OUTCOME MEASURES: Muscle volumes expressed relative to (1) a normative database presurgery and postsurgery, (2) limb symmetry presurgery and postsurgery, and (3) percentage change presurgery to postsurgery. Quadriceps function was quantified by normalized knee extension maximal voluntary isometric contraction torque and central activation ratio. RESULTS: Involved vastus lateralis and tibialis anterior were consistently smaller than healthy individuals (z < -1 SD) presurgery and postsurgery in all patients. Involved rectus femoris and vastus lateralis were more than 15% smaller than the contralateral limb presurgery, whereas the involved rectus femoris, gracilis, vastus medialis, vastus intermedius, and vastus lateralis muscle volumes exceeded 20% asymmetry postoperatively. Involved gracilis and semitendinosus atrophied more than 30% from presurgery to postsurgery. Involved maximal voluntary isometric contraction torque and central activation ratio increased by 12.7% and 12.5%, respectively, yet strength remained 33.2% asymmetric postsurgery. CONCLUSIONS: Adaptations in lower-extremity muscle volumes are present following ACL injury and reconstruction. Anterior thigh and shank muscles were smaller than healthy individuals, and large asymmetries in quadriceps volumes were observed presurgery and postsurgery. Selective atrophy of the semitendinosus and gracilis occurred following surgery. Volumetric deficits of the quadriceps musculature may exist despite improvements in muscle strength and activation.

Quadriceps Strength Testing Practices & Barriers During Return to Sport from ACL Reconstruction: A Survey of Collegiate Athletic Trainers.

CONTEXT: Quadriceps strength is a key outcome for guiding rehabilitation and return to sport-specific activities after ACL reconstruction (ACLR) surgery. OBJECTIVES: 1) Describe the quadriceps strength testing practices and barriers college athletic trainers (ATs) are using and experiencing when returning patients to sport-specific activities after ACLR. 2)Compare testing methods between college ATs working in the National Collegiate Athletic Association (NCAA) Division I setting and other college settings. DESIGN: Cross-sectional. SETTING: Online survey. PATIENTS OR OTHER PARTICIPANTS: 243 full-time collegiate ATs who had primarily overseen/directed an ACLR rehabilitation in the past five years (age: 34.8±10.7, years of AT practice: 11.7±9.3, NCAA division I setting: 56%). MAIN OUTCOMES: Our survey included four sections: Demographics, General ACLR rehabilitation practices, Quadriceps strength testing methods & criteria, and Quadriceps strength testing barriers. RESULTS: Knee muscle strength was the most common (98%) outcome collegiate ATs use when determining whether an ACLR patient is ready to progress to sport-specific activities. Manual muscle testing (MMT) was the most used testing method (57%), followed by isokinetic dynamometry (IKD) (48%), repetition max (RM) testing (35%) and handheld dynamometry (HHD) (22%). Most ATs (63-64%) used >90% side-to-side symmetry as their return to sport-specific activities criteria. Lack of equipment needed (83%), lack of financial means (28%), and lack of training/education (20%) were the barriers that most limited ATs use of IKD testing, the gold-standard testing method. Compared to ATs in other settings, a greater proportion of ATs working in the NCAA Division I setting used IKD testing (65% vs 28%) and a smaller proportion used MMT (47% vs 70%). CONCLUSIONS: While almost all college ATs considered knee muscle strength an important outcome to assess when returning patients to sport-specific activities after ACLR, quadriceps strength testing practices were highly variable among ATs and may be impacted by access to necessary resources.

Associations Between Race & Socioeconomic Status, Lower Extremity Strength, and Patient Reported Outcomes Following Anterior Cruciate Ligament Reconstruction.

CONTEXT: There are significant disparities in access to health care, but there are limited data about the impact of race and socioeconomic status (SES) on postoperative outcomes following anterior cruciate ligament (ACL) reconstruction (ACLR) surgery. OBJECTIVE: To identify associations between area deprivation index (ADI), strength measures and patient-reported outcomes (PROs) following ACLR as well as to examine differences in outcomes between race, sex, and race. DESIGN: Case control study in a single hospital setting. SETTING: Database secondary analysis. PATIENTS OR OTHER PARTICIPANTS: Data was collected from 340 patients who underwent primary, isolated, unilateral ACLR. MAIN OUTCOME MEASURES: Strength measures and PROs were obtained at patients' postoperative assessments at approximately six months post-surgery. Area Deprivation Index values were calculated on each patient's census tract, determined through medical records review. Correlations were conducted to determine the relationship between ADI and KOOS measures, IKDC, and limb symmetry on strength measurements. The racial composition of the sample was heavily skewed and was excluded from statistical analyses. RESULTS: ADI was weakly correlated with IKDC (ρ=0.11, p=0.04) outcomes, with more disadvantaged patients reporting better quality of life and knee function. ADI was not correlated with other outcomes of interest. The median ADI value of the sample was 32 (range 1-86 [IQR 19-47]). CONCLUSIONS: Our study revealed a weak correlation between higher levels of socioeconomic disadvantage as measured by ADI and improved subjective assessment of knee function and quality of life as measured by IKDC. These findings are contrary to what other studies on this subject have found and highlight the importance of further research into the impact of SES and other social determinants of health on post ACLR outcomes.

A gender comparison of central and peripheral neuromuscular function after exercise.

CONTEXT: Central and peripheral muscle fatigue during exercise may exacerbate neuromuscular factors that increase risk for noncontact anterior cruciate ligament injury. OBJECTIVE: To compare lower extremity motor-evoked potentials (MEPs), muscle strength, and electromyography (EMG) activation after an exercise protocol. DESIGN: Pretest, posttest group comparison. SETTING: University laboratory. PARTICIPANTS: 34 healthy volunteers (17 female, age = 21.9 ± 2.3 years, weight = 77.8 ± 3.0 kg, height = 171.1 ± 6.6 cm, and 17 male, age = 23.4 ± 6.5 years, weight = 81.6 ± 3.3 kg, height = 179.6 ± 7.3 cm). INTERVENTION: A standardized 30-min exercise protocol that involved 5 repeated cycles of uphill walking, body-weight squatting, and step-ups. MAIN OUTCOME MEASURES: Quadriceps and hamstring MEP amplitude (mV) and transmission velocity normalized to subject height (m/s) were elicited via transcranial magnetic stimulation and measured via surface EMG. Quadriceps and hamstring peak EMG activation (% MVIC) and peak torque (Nm/kg) were measured during MVICs. Separate ANCOVAs were used to compare groups after exercise while controlling for baseline measurement. RESULTS: At baseline, males exhibited significantly greater knee-extension torques (males = 2.47 ± 0.68 Nm/kg, females = 1.95 ± 0.53 Nm/kg; P = .036) and significantly higher hamstring MEP amplitudes (males = 223.5 ± 134.0 mV, females = 89.3 ± 77.6 mV; P = .007). Males exhibited greater quadriceps MEP amplitude after exercise than females (males = 127.2 ± 112.7 mV, females = 32.3 ± 34.9 mV; P = .016). CONCLUSIONS: Males experienced greater peripheral neuromuscular changes manifested as more pronounced reductions in quadriceps torque after exercise. Females experienced greater central neuromuscular changes manifested as more pronounced reduction in quadriceps MEP amplitude. Reduced central neural drive of the quadriceps coupled with knee-extension torque preservation after exercise may increase risk of knee injury in females.

Prospective, Randomized, Double-Blind Evaluation of the Efficacy of a Single-Dose Hyaluronic Acid for the Treatment of Patellofemoral Chondromalacia.

BACKGROUND: Patellofemoral pain is common in the young and active populations. Nonoperative management is limited and focuses on physical therapy. Hyaluronic acid (HA) is an injectable device that has been used for the treatment of knee osteoarthritis. HYPOTHESIS: A single injection of HA would reduce pain and improve function in patients with patellofemoral pain who had previously failed conservative management. STUDY DESIGN: Randomized controlled trial; Level of evidence, 2. METHODS: A total of 86 patients with patellofemoral pain (65 females, 21 males; mean ± SD age, 27.0 ± 7.7 years; height, 168.6 ± 8.9 cm; weight, 74.6 ± 17.0 kg; body mass index, 26.2 ± 5.2 kg/m2) enrolled in this study after failing conservative management. Patients were randomly allocated to either 6 mL of HA or a sham injection. All patients were prescribed an additional home exercise program, including lower extremity strengthening and flexibility exercises, and were evaluated at 1, 3, and 6 months. Outcome assessments included patellofemoral pain assessment with a visual analog scale during a single-legged squat, KOOS (Knee injury and Osteoarthritis Outcome Score), Kujala score, Tegner activity rating, and normalized isometric knee extension strength. Group assignment was revealed after the 6-month assessment, and crossover treatment was offered to patients in the sham group who were still symptomatic. Linear mixed models were used to compare outcomes between groups and across time. RESULTS: A total of 45 patients were randomized to HA injection and 41 to sham, with 6 patients lost to follow-up (93% follow-up rate). Patients in both groups experienced a significant reduction in visual analog pain ratings and significant improvements in all domains of the KOOS and in Kujala scores at 6 months when compared with baseline measurement (P < .05); however, there was no significant difference between groups. There were no differences observed over time or between groups for normalized knee extension strength or Tegner activity rating (P > .05). CONCLUSION: HA injection had no clinically meaningful effect on pain or functional outcomes in patients diagnosed with patellofemoral pain. Improvements were observed for both groups in patient-reported pain and function, with no change in quadriceps strength or activity rating. REGISTRATION: NCT01771952 (ClinicalTrials.gov identifier).

Thoracic spine thrust manipulation improves pain, range of motion, and self-reported function in patients with mechanical neck pain: a systematic review.

STUDY DESIGN: Systematic review. BACKGROUND: Neck pain is a common diagnosis in the physical therapy setting, yet there is no gold standard for treatment. This study is part of a growing body of literature on the use of thoracic spine thrust manipulation for the treatment of individuals with mechanical neck pain. OBJECTIVE: The purpose of this systematic review was to determine the effects of thoracic spine thrust manipulation on pain, range of motion, and self-reported function in patients with mechanical neck pain. METHODS: Six online databases were comprehensively searched from their respective inception to October 2010. The primary search terms included "thoracic mobilization," "thoracic spine mobilization," "thoracic manipulation," and "thoracic spine manipulation." Of the 44 studies assessed for inclusion, 6 randomized controlled trials were retained. Between-group mean differences and effect sizes for pretreatment-to-posttreatment change scores, using Cohen's d formula, were calculated for pain, range of motion, and subjective function at all stated time intervals. RESULTS: Effect size point estimates for the pain change scores were significant for global assessment across all studies (range, 0.38-4.03) but not conclusively significant at the end range of active rotation (range, 0.02-1.79). Effect size point estimates were large among all range-of-motion change measures (range, 1.40-3.52), and the effect size point estimates of the change scores among the functional questionnaires (range, 0.47-3.64) also indicated a significant treatment effect. CONCLUSIONS: Thoracic spine thrust manipulation may provide short-term improvement in patients with acute or subacute mechanical neck pain. However, the body of literature is weak, and these results may not be generalizable. LEVEL OF EVIDENCE: Therapy, level 1b-.