Since 1996, when the first report of sex differences in neuromuscular function appeared in the literature with the aim of understanding why physically active females are at greater risk of injuring the ACL than their male counterparts, many authors have reported on sex differences in neuromuscular and biomechanical function. Based on this collective literature, clear sex differences in muscle activation and movement patterns have been identified, leading to the focus on neuromuscular and biomechanical factors as the key reasons for the sex differences in ACL injury rates. In turn, prevention programs have been developed to reduce dynamic knee loading through
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MA, ATC,
MS, CAT(C), ATC,
PhD, ATC,
PhD, and
PhD, ATC, FNATA, FACSM
With regard to sideline concussion testing, the effect of fatigue associated with different types of exercise on postural control is unknown. To evaluate the effects of fatigue on postural control in healthy college-aged athletes performing anaerobic and aerobic exercise protocols and to establish an immediate recovery time course from each exercise protocol for postural control measures to return to baseline status. Counterbalanced, repeated measures. Research laboratory. Thirty-six collegiate athletes (18 males, 18 females; age = 19.00 ± 1.01 years, height = 172.44 ± 10.47 cm, mass = 69.72 ± 12.84 kg). Participants completed 2 counterbalanced sessions within 7 days. Each session consisted of 1 exercise protocol followed by postexercise measures of postural control taken at 3-, 8-, 13-, and 18-minute time intervals. Baseline measures were established during the first session, before the specified exertion protocol was performed. Balance Error Scoring System (BESS) results, sway velocity, and elliptical sway area. We found a decrease in postural control after each exercise protocol for all dependent measures. An interaction was noted between exercise protocol and time for total BESS score (P = .002). For both exercise protocols, all measures of postural control returned to baseline within 13 minutes. Postural control was negatively affected after anaerobic and aerobic exercise protocols as measured by total BESS score, elliptical sway area, and sway velocity. The effect of exertion lasted up to 13 minutes after each exercise was completed. Certified athletic trainers and clinicians should be aware of these effects and their recovery time course when determining an appropriate time to administer sideline assessments of postural control after a suspected mild traumatic brain injury.Abstract
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MS, ATC,
PhD,
PhD, ATC, and
PhD
The Cuff Link is a closed kinetic chain rehabilitation apparatus for the upper extremity. Limited research has established its effectiveness to elicit muscle activation of the scapular muscles. To determine if scapular muscle activation differs in response to 2 upper extremity closed kinetic chain exercises: Cuff Link and standard push-up. A single-group, repeated-measures design. Controlled laboratory. Twenty-eight healthy individuals (13 women: age = 19.69 ± 1.55 years, height = 167.44 ± 9.52 cm, mass = 61.00 ± 8.79 kg; 15 men: age = 22.00 ± 3.91 years, height = 181.44 ± 6.60 cm, mass = 82.36 ± 13.23 kg) with no history of shoulder or low back injury volunteered to participate in this study. Participants performed 10 trials of complete revolutions on the Cuff Link and 10 full–weight-bearing push-ups. We controlled trial velocity and randomized order. Trunk and shoulder positions were normalized to the participant's height. Using surface electromyography, we recorded muscle activity of the serratus anterior, middle trapezius, and lower trapezius. Rectified and smoothed electromyography data for the serratus anterior, middle trapezius, and lower trapezius were normalized as a percentage of the maximal voluntary isometric contractions (%MVIC). Mean muscle activity of the serratus anterior, middle trapezius, and lower trapezius. We used paired-samples t tests to analyze the mean data for each condition. The α level was adjusted to .016 to avoid a type I error. Middle trapezius %MVIC was greater during push-ups (27.01 ± 20.40%) than during use of the Cuff Link (11.49 ± 9.46%) (P = .001). Lower trapezius %MVIC was greater during push-ups (36.07 ± 18.99%) than during use of the Cuff Link (16.29 ± 8.64%) (P = .001). There was no difference in %MVIC for the serratus anterior between conditions. The push-up demonstrated greater middle trapezius and lower trapezius activation levels compared with the Cuff Link. However, the push-up had a high participant failure rate. Because serratus anterior activation levels were similar, the Cuff Link may be an appropriate alternative for individuals lacking the upper body strength to perform a push-up.Abstract
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PhD, CAT(C) and
PhD
The modified Thomas test is commonly used in the clinical setting to assess flexibility about the thigh region. To evaluate the clinical reliability of the modified Thomas test for evaluating the flexibility of the rectus femoris muscle about the knee joint. Descriptive laboratory study using a test-retest design. Institution-based clinical orthopaedic setting. Fifty-seven individuals between the ages of 18 and 45 years with no history of trauma participated. Of those, 54 completed the study. Three Board-certified athletic therapists with an average of 12.67 years of sport medicine expertise assessed rectus femoris flexibility using pass/fail and goniometer scoring systems. A retest session was completed 7 to 10 days later. Parametric and nonparametric tests were used to compare participants' test-retest results. Chance-corrected κ values (intrarater x¯ = 0.40, 95% confidence interval [CI] = 0.30, 0.54; interrater x¯ = 0.33, 95% CI = 0.23, 0.41) indicated generally poor levels of reliability for pass/fail scoring. Intraclass correlation coefficient (ICC) values (intrarater x¯ = 0.67, 95% CI = 0.55, 0.76; interrater x¯ = 0.50, 95% CI = 0.40, 0.60) indicated fair to moderate levels of reliability for goniometer data. Measurement error values (standard error of measurement = 7°, method error = 6°, and coefficient of variation = 13%) and Bland-Altman plots (with 95% limits of agreement) further demonstrated the degree of intrarater variance for each examiner when conducting the test. These results call into question the statistical reliability of the modified Thomas test and provide clinicians with important information regarding its reliability limits when used to clinically assess flexibility of the rectus femoris muscle about the knee joint in a physically active population. More research is needed to ascertain the variables that may confound the statistical reliability of this orthopaedic technique.Abstract
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PhD,
BSc,
PhD,
MSc, and
BSc
Single-limb squats on a decline angle have been suggested as a rehabilitative intervention to target the knee extensors. Investigators, however, have presented very little empirical research in which they have documented the biomechanics of these exercises or have determined the optimum angle of decline used. To determine the involvement of the gastrocnemius and rectus femoris muscles and the external ankle and knee joint moments at 60° of knee flexion while performing a single-limb squat at different decline angles. Participants acted as their own controls in a repeated-measures design. We recruited 10 participants who had no pain, injury, or neurologic disorder. Participants performed single-limb squats at different decline angles. Angle-specific knee and ankle moments were calculated at 60° of knee flexion. Angle-specific electromyography (EMG) activity was calculated at 60° of knee flexion. Integrated EMG also was calculated to determine the level of muscle activity over the entire squat. An increase was seen in the knee moments (P < .05) and integrated EMG in the rectus femoris (P < .001) as the decline angle increased. A decrease was seen in the ankle moments as the decline angle increased (P = .001), but EMG activity in the gastrocnemius increased between 16° and 24° (P = .018). As the decline angle increased, the knee extensor moment and EMG activity increased. As the decline angle increased, the ankle plantar-flexor moments decreased; however, an increase in the EMG activity was seen with the 24° decline angle compared with the 16° decline angle. This indicates that decline squats at an angle greater than 16° may not reduce passive calf tension, as was suggested previously, and may provide no mechanical advantage for the knee.Abstract
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Observational Studies
PhD, CAT(C),
PhD,
PhD, and
MSc, CAT(C)
Orthopaedic assessment skills are critical to the success of athletic therapists and trainers. The Standardized Orthopedic Assessment Tool (SOAT) has been content validated. To establish interrater reliability of the SOAT. Thirty-two college students, 10 raters, and 2 standardized patients (SPs) from Calgary, Alberta, Canada. Randomized observational study. Students were allowed 30 minutes to complete a mock orthopaedic assessment of an SP with an injury specific to a region of the body (shoulder, knee, or ankle). Using the region-specific SOAT, raters and SPs evaluated students' orthopaedic assessment skills. The sum totals of the SOAT for 2 raters and 1 SP were used to calculate each student's performance scores for respective scenarios. Scale reliability analysis (Cronbach α) was completed on the SOAT for each of the 3 body-region examinations. The mean overall reliability of 3 SOATs (ie, ankle, knee, and shoulder) was positive: α = .85 with the SP scores factored into the equation and α = .86 without the SP scores factored into the equation. Reliability for the ankle region was highest (α = .91), followed by the knee (α = .83) and the shoulder (α = .82). The study sample size was small, but the results will enable further study with generalization to a broader audience of athletic therapists and athletic trainers. Because a baseline measure of reliability was established using a robust statistical analysis, future researchers can employ more stringent statistical analysis and focus on the effects of various pedagogical techniques to teach and learn the underlying construct of clinical competence in orthopaedic assessment.Abstract
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MSc,
PhD,
MSc,
MSc,
MSc,
MSc,
PhD, and
PhD
Elite distance runners (EDR) must optimize their nutrition to maintain their demanding training schedules. To develop a nutrition concept for EDR based on energy and macronutrient expenditures. This theoretical study provides calculations for macronutrient and energy expenditures of EDR. Anthropometric and metabolic characteristics of EDR were assumed based on average real EDR. University of Kiel. Three prototypic types of male EDR described in the literature as type I (TI; body mass = 72 kg, respiratory quotient = 0.9 at rest, fast-twitch muscle fibers = 60% to 70%), type II (TII; body mass = 67 kg, respiratory quotient = 0.82 at rest, fast-twitch muscle fibers = 50%), and type III (TIII; body mass = 60 kg, respiratory quotient = 0.75 at rest, fast-twitch muscle fibers = 30% to 40%). We calculated the macronutrient and energy expenditures of the 3 types of EDR according to body mass, respiratory quotient, and percentage of fast-twitch muscle fibers. We found that the average energy expenditure was 3750 kcal · d−1 for TI runners, 3463 kcal · d−1 for TII runners, and 3079 kcal · d−1 for TIII runners. The carbohydrate (CHO) expenditure reached an average value of 10.0 g · kg−1 · d−1 for TI runners, 8.0 g · kg−1 · d−1 for TII runners, and 4.7 g · kg−1 · d−1 for TIII runners. When the EDR accomplished running sessions at a pace ≥100% of maximum oxygen consumption, all types of runners had a CHO demand of about 10 g · kg−1 · d−1. The TI and TII runners need a CHO intake of 8 to 10 g · kg−1 · d−1. For the TIII runners, a CHO intake >6 g · kg−1 · d−1 is necessary during anaerobic training sessions. Nutrition concepts must be differentiated for EDR according to metabolic and anthropometric characteristics of the runners and their special training emphases.Abstract
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PhD, LAT, ATC,
PhD, and
PhD, ATC, FNATA, FACSM
Work-family conflict (WFC) involves discord that arises when the demands of work interfere with the demands of family or home life. Long work hours, minimal control over work schedules, and time spent away from home are antecedents to WFC. To date, few authors have examined work-family conflict within the athletic training profession. To investigate the occurrence of WFC in certified athletic trainers (ATs) and to identify roots and factors leading to quality-of-life issues for ATs working in the National Collegiate Athletic Association Division I-A setting. Survey questionnaire and follow-up, in-depth, in-person interviews. Division I-A universities sponsoring football. A total of 587 ATs (324 men, 263 women) responded to the questionnaire. Twelve ATs (6 men, 6 women) participated in the qualitative portion: 2 head ATs, 4 assistant ATs, 4 graduate assistant ATs, and 2 AT program directors. Multiple regression analysis was performed to determine whether workload and travel predicted levels of WFC. Analyses of variance were calculated to investigate differences among the factors of sex, marital status, and family status. Interviews were transcribed verbatim and then analyzed using computer software as well as member checks and peer debriefing. The triangulation of the data collection and multiple sources of qualitative analysis were utilized to limit potential researcher prejudices. Regression analyses revealed that long work hours and travel directly contributed to WFC. In addition to long hours and travel, inflexible work schedules and staffing patterns were discussed by the interview participants as antecedents to WFC. Regardless of sex (P = .142), marital status (P = .687), family status (P = .055), or age of children (P = .633), WFC affected Division I-A ATs. No matter their marital or family status, ATs employed at the Division I-A level experienced difficulties balancing their work and home lives. Sources of conflict primarily stemmed from the consuming nature of the profession, travel, inflexible work schedules, and lack of full-time staff members.Abstract
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PhD, LAT, ATC,
PhD,
PhD, ATC, FNATA, FACSM, and
PhD
Previous researchers have shown that work-family conflict (WFC) affects the level of a person's job satisfaction, life satisfaction, and job burnout and intentions to leave the profession. However, WFC and its consequences have not yet been fully investigated among certified athletic trainers. To investigate the relationship between WFC and various outcome variables among certified athletic trainers working in National Collegiate Athletic Association Division I-A settings. A mixed-methods design using a 53-item survey questionnaire and follow-up in-depth interviews was used to examine the prevalence of WFC. Division I-A universities sponsoring football. A total of 587 athletic trainers (324 men, 263 women) responded to the questionnaire, and 12 (6 men, 6 women) participated in the qualitative portion of the mixed-methods study. We calculated Pearson correlations to determine the relationship between WFC and job satisfaction, life satisfaction, and job burnout. Regression analyses were run to determine whether WFC was a predictor of job satisfaction, job burnout, or intention to leave the profession. Interviews were transcribed verbatim and then analyzed using the computer program N6 as well as member checks and peer debriefing. Negative relationships were found between WFC and job satisfaction (r = −.52, P < .001). Positive were noted between WFC and job burnout (r = .63, P < .001) and intention to leave the profession (r = .46, P < .001). Regression analyses revealed that WFC directly contributed to job satisfaction (P < .001), job burnout (P < .001), and intention to leave the profession (P < .001). Overall, our findings concur with those of previous researchers on WFC and its negative relationships to job satisfaction and life satisfaction and positive relationship to job burnout and intention to leave an organization. Sources of WFC, such as time, inflexible work schedules, and inadequate staffing, were also related to job burnout and job dissatisfaction in this population.Abstract
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PhD, ATC and
MS, ATC
To perform a systematic review to determine the healing time of the lateral ankle ligaments after an acute ankle sprain. We identified English-language research studies from 1964 to 2007 by searching MEDLINE, Physiotherapy Evidence Database (PEDro), SportDiscus, and CINAHL using the terms ankle sprain, ankle rehabilitation, ankle injury, ligament healing, and immobilization. We selected studies that described randomized, controlled clinical trials measuring ligament laxity either objectively or subjectively immediately after injury and at least 1 more time after injury. Two reviewers independently scored the 7 studies that met the inclusion criteria. Because of differences in study designs, a meta-analysis could not be performed. Effect sizes and confidence intervals could be calculated only for 1 study. The percentages of subjective and objective instability were calculated for the remaining studies. Ankle laxity improved over a period of 6 weeks to 1 year. One author showed stress talar tilt values of 16.10 ± 8.8° immediately after injury and 3.4 ± 3.6° at 3 months after injury. In 2 articles, the authors reported that positive anterior drawer tests were still present in 3% to 31% of participants at 6 months after injury. Additionally, feelings of instability affected 7% to 42% of participants up to 1 year after injury. In the studies that we examined, it took at least 6 weeks to 3 months before ligament healing occurred. However, at 6 weeks to 1 year after injury, a large percentage of participants still had objective mechanical laxity and subjective ankle instability. Direct comparison among articles is difficult because of differences in methods. More research focusing on more reliable methods of measuring ankle laxity is needed so that clinicians can know how long ligament healing takes after injury. This knowledge will help clinicians to make better decisions during rehabilitation and for return to play.Abstract
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Research Retreat IV: ACL Injuries–The Gender Bias, April 3-5, 2008, Greensboro, NC
Consensus Statement
PhD, ATC, FNATA, FACSM,
PhD, ATC, and
PhD, ATC
In April 2008, more than 80 attendees from across the United States and Canada participated in the fourth research retreat focused on the gender bias in anterior cruciate ligament (ACL) injury. The retreat was cofounded by Irene Davis, PhD, PT, and Mary Lloyd Ireland, MD, who hosted the 3 previous research retreats in Lexington, Kentucky, in April of 2001, 2003, and 2006. In the first year (2001), a consensus document of what we know, don't know, and still need to know related to this problem was developed.1 Each subsequent retreat has revisited and updated the previous consensus statement
The ACL is loaded by a variety of combined sagittal and nonsagittal mechanisms during dynamic sport postures considered to be high risk.1–6 In vivo strain of the ACL is related to maximal load and timing of ground reaction forces.7,8 Females typically display a more erect (upright) posture when contacting the ground during the early stages of deceleration tasks.9–12 Maturation influences biomechanical and neuromuscular factors.13–20 Fatigue alters lower limb biomechanical and neuromuscular factors suggested to increase ACL injury risk.2,21–23 TheWhat We Know
The female ACL is smaller in length, cross-sectional area, and volume compared with the male ACL, even after adjusting for body anthropometry.1 The female's femoral notch height is larger, but the femoral notch angle is smaller than in males, which may influence femoral notch impingement theory. Femoral notch width is a good predictor of ACL size (area and volume) in males but not in females. Femoral notch angle is a good predictor of ACL size in females but not in males.1 The female ACL is less stiff (has a lower modulus of elasticity) and failsWhat We Know
A consensus is emerging from the literature that the likelihood of suffering an ACL injury is not evenly distributed across the menstrual cycle; instead, the risk of suffering an ACL disruption is greater during the preovulatory phase of the menstrual cycle than in the postovulatory phase.1–5 During the preovulatory phase, hormone levels are changing dramatically, falling to their nadirs with the onset of menses and once again rising rapidly near ovulation. Evidence exists for sex hormone receptors (estrogen, testosterone, and relaxin) on the human ACL.6–10 Evidence exists for sex hormoneWhat We Know
Various training programs that incorporate elements of balance training, plyometric training, education, strengthening, and feedback alter biomechanical and neuromuscular variables thought to contribute to ACL injury.1–5 Various intervention programs reduce the incidence of ACL injuries.6–8 The protective effects of ACL injury prevention training programs appear to be transient.9–11 What are the mechanisms underlying the success of various injury prevention programs? Specifically, which elements of an injury prevention program (strengthening, plyometrics, etc) produce the desired protective effect? How much training stimulus (ie, duration and timing)What We Know
What We Don't Know
Summaries
PhD
Multiple risk factors, both modifiable and nonmodifiable, are known to manifest within the noncontact anterior cruciate ligament (ACL) injury mechanism.1 I will primarily address neuromechanical contributions to injury risk, which are often a key focus at meetings of this nature; such factors are amenable to training and, hence, largely modifiable. I hope, however, that as the reader progresses through the document, the critical importance of underlying nonmodifiable factors within the resultant neuromechanical strategy will not be lost. Sexual dimorphism in modifiable neuromuscular factors linked to ACL injury is well documented, with the “female” movement pattern interpreted as riskier.
PhD and
PhD, ATC, FNATA, FACSM
The fundamental basis for knee trauma prevention research is that injuries occur in patterns reflecting the underlying causes. Understanding the underlying causes or risk factors for one of the more severe sport-related knee injuries, an anterior cruciate ligament (ACL) disruption, is important for developing intervention strategies, identifying those at increased risk of this injury, and allowing targeted interventions. The risk factors for ACL injury have been considered either internal or external to an individual. In the following review, we focus on what is known about 2 categories of internal risk factors: an athlete's anatomy and menstrual cycle phase.THE ASSOCIATION
Abstracts
Ground Reaction Forces, but Not Knee Muscle Activation, or Sagittal Knee Joint Stiffness Differ Between Female Dancers and Basketball Players during Drop Jumps Introduction: Anterior Cruciate Ligament (ACL) injuries frequently occur during landing. Although both dancers and athletes regularly perform landings, dancers reportedly have lower rates of ACL injury than athletes. During activity, greater knee muscle coactivation can increase knee joint stiffness, and be protective by not allowing the joint to reach harmful ranges.Abstract #1
Reliability and Validity of the Functional Assessment of Neurocognition in Sport (FANS): A Paradigm Shift in Post-Concussion Return-to-Sport Decision-Making
Landon B. LempkePhD, ATC,
Benjamin L. BrettPhD, and
Douglas P. TerryPhD,ABPP
Corticospinal Excitability during Standing and Its Association with Postural Control Following Acute Lateral Ankle Sprain.
Joosung Kim,
Arlette C. Perry,
Kevin A. Jacobs,
Brian Arwari,
Soyeon Ahn, and
Kyung-Min Kim
Driving After Concussion: Clinical Measures Associated with Post-concussion
Kumiko Hashida,
Julia Drattell,
Kim Love,
Robert C. Lynall,
Russell K. Gore,
Hannes Devos, and
Julianne D. Schmidt
The role of shoulder posture in pitching mechanics and injury risk in high school baseball pitchers
Yi-Hsuan WengPT, MS,
Tsun-Shun HuangPT, PhD, and
Jiu-Jenq LinPT, PhD
Healthcare Utilization and Provider Workload in Collegiate Student Athletes for Acute, Overuse, Time-Loss and Non-Time-Loss Injuries
Cathleen N. BrownPhD, ATC,
Viktor E. BovbjergMPH, PhD,
Michael T. SoucyMS,
SeokJae ChoeMA, ATC,
Michael FredericsonMD, and
Janet E. SimonPhD, ATC
JAT eISSN: 1938-162X
JAT ISSN: 1062-6050
ATEJ ISSN: 1947-380X
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