Secondary School Athletic Trainers' Experiences With Organizational Conflict: A Comparison Across Employment Models.

CONTEXT: Athletic training is a multifaceted profession characterized by interpersonal relationships and a team approach to care. Collaborative relationships, by nature, open the door to conflict, which has been reported frequently in the collegiate athletic setting. However, secondary school athletic trainers' (ATs') experiences with conflict and pressure in their role are not readily understood. OBJECTIVE: To measure the extent and sources of stress, pressure, and conflict within the secondary school athletic training setting and determine if differences exist across employment characteristics. DESIGN: Cross-sectional study. SETTING: Secondary school athletics. PATIENTS OR OTHER PARTICIPANTS: Secondary school ATs (n = 725, age = 39.8 ± 10.5 years, years certified = 16.7 ± 9.7, years in current role = 10.6 ± 7.8). MAIN OUTCOME MEASURES: Participants were asked to reply to an online questionnaire with quantitative measures pertaining to organizational conflict and workplace dynamic. Employment type (school district employee, school district teacher, medical or university facility, independent contractor) and status (full time, part time) served as independent variables. Likert-scale scores (1 = strongly agree to 5 = strongly disagree; 1 = always to 5 = never) and perceived sources of stress, pressure, and conflict were the dependent variables. Analyses consisted of Kruskal-Wallis tests with Mann-Whitney U post hoc tests and odds ratios to assess associations between variables of interest. RESULTS: We obtained a 15.3% response rate (725/4745). Although the ATs reported experiencing conflict and pressure, these experiences were relatively infrequent and not universal. Compared with part-time ATs, full-time ATs described higher ratings of strong relationships with coaches (P = .003) and principals (P = .002). The most frequently identified sources of conflict were parents (59%) and coaches (53.9%), followed by athletes (32.6%). Full-time ATs were 1.6 times more likely to report experiencing conflict with a coach than part-time ATs (odds ratio = 1.550, 95% CI = 1.037, 2.317; P = .040). CONCLUSIONS: Secondary school ATs' experiences regarding organizational conflict were relatively positive. Instances of pressure and conflict were noted, though relatively infrequently, and these experiences were largely uninfluenced by employment type.

Preseason Neck Mobility Is Associated With Throwing-Related Shoulder and Elbow Injuries, Pain, and Disability in College Baseball Pitchers.

BACKGROUND: Shoulder and elbow injuries in baseball pitchers, which can lead to significant pain and disability, have been on the rise at all levels of play for 3 decades. Despite anatomic and neurophysiological relationships, neck mobility has not been explored as a contributor to shoulder and elbow injuries in baseball pitchers. HYPOTHESIS: Impaired neck mobility will increase the risk of shoulder and elbow injuries in college baseball pitchers. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Posture, neck mobility, and shoulder passive range of motion were measured in healthy college baseball pitchers during the 2018 preseason. Time loss (days lost because of shoulder or elbow injuries) and patient-reported disability via Functional Arm Scale for Throwers (FAST) scores were used to dichotomize pitchers into injured and uninjured groups. Receiver operating characteristic curves were generated, and accuracy values and risk ratios (RRs) were calculated to assess the diagnostic utility of the physical measures. Time-to-injury analysis was conducted to assess the timing of injuries. RESULTS: A total of 49 pitchers (mean age, 19.92 ± 1.48 years; mean height, 187.04 ± 6.02 cm; mean weight, 89.14 ± 12.08 kg) completed the study. There were 10 pitchers (20.4%) who sustained a time-loss injury >7 days because of a shoulder or elbow injury. A Cervical Flexion-Rotation Test (CFRT) finding on the dominant side of ≤39° resulted in over 9 times the increased risk of time-loss injuries (RR, 9.38 [95% CI, 1.28-68.49]). Time-to-injury analysis demonstrated differences between the 2 groups (χ2 = 7.667; P = .01). Pitchers with a >39.25° finding on the CFRT played a mean 109.4 of 112 days (95% CI, 105-114) before the injury, while pitchers with ≤39.25° only played 83.6 of 112 days (95% CI, 68-99). A CFRT finding of ≤38° (RR, 3.91 [95% CI, 1.23-12.39]), cervical flexion range of motion of ≤64° (RR, 10.56 [95% CI, 1.50-74.34]), and weight of >86.9 kg (RR, 10.42 [95% CI, 1.14-213.70]) were also associated with an increased risk of patient-reported pain and disability on the FAST pitcher module. CONCLUSION: College baseball pitchers with less neck mobility during the preseason had an increased risk of time loss and shoulder and elbow disability during the season. The predictive value of these measures as part of a risk screening profile should be further explored.

Quadriceps Inhibition After Naturally Occurring Patellar Tendon Damage and Pain.

CONTEXT: After knee-joint injury, pain, effusion, and mechanoreceptor damage alter afferent signaling, which can result in quadriceps inhibition and subsequent weakness. The individual contributions of each factor to inhibition remain unclear due to confounding knee-joint injuries and indirect experimental models. OBJECTIVE: To characterize the influence of naturally occurring knee damage and pain on quadriceps neuromuscular function in individuals with patellar tendinopathy. DESIGN: Cross-sectional study. SETTING: Research laboratory. PATIENTS OR OTHER PARTICIPANTS: Twenty participants who self-reported patellar tendinopathy (PT) and 10 healthy control individuals underwent ultrasonic tendon assessment. Injured participants were dichotomized by an orthopaedic surgeon into groups with (1) pain and structural tendon abnormality and (2) regional pain alone. MAIN OUTCOME MEASURE(S): Quadriceps inhibition was assessed with the Hoffman reflex and the central activation ratio via the superimposed-burst technique. Normally distributed measures were analyzed using a 1-way analysis of variance and post hoc independent t tests. Kruskal-Wallis tests with post hoc Mann-Whitney U tests were used to analyze nonnormally distributed data. An a priori α level of P ≤ .05 was set. RESULTS: Control participants presented with more spinal-reflex excitability (0.37 ± 0.23) than the PT (0.10 ± 0.06; P = .03) and regional-pain (0.18 ± 0.05; P = .02) groups. Knee-extension strength was greater in the control (3.37 ± 0.59 Nm/kg) than in the PT (2.41 ± 0.67 Nm/kg; P = .01) group but not the regional-pain group (3.05 ± 0.66 Nm/kg; P = .24). Control individuals presented with more quadriceps activation (97.93% ± 3.12) than the PT (84.44% ± 16.98; P < .01) and regional-pain (91.17% ± 10.56; P = .01) groups. No differences were present for any measures between the PT and regional-pain groups (P values > .05). CONCLUSIONS: Deficits in spinal-reflex excitability, quadriceps activation, and strength were present in both the PT and regional-pain groups. A combination of pain and structural damage appeared to have the greatest negative effect on quadriceps function, as only the PT group presented with neuromuscular outcomes that failed to meet clinical thresholds.

Dynamic Leap and Balance Test: Ability to Discriminate Balance Deficits in Individuals With Chronic Ankle Instability.

CONTEXT: The Dynamic Leap Balance Test (DLBT) is a new dynamic balance task that requires serial changes in base of support with alternating limb support and recovery of dynamic stability, as compared with the Y modification of the Star Excursion Balance Test (Y-SEBT), which assesses dynamic stability over an unchanging base of support. OBJECTIVES: To assess the dynamic balance performance in 2 different types of dynamic balance tasks, the DLBT and the SEBT, in subjects with unilateral chronic ankle instability (CAI) when compared with matched controls. The authors hypothesized that the DLBT score would significantly differ between the CAI involved and uninvolved limbs (contralateral and healthy matched) and demonstrate a modest (r = .50) association with the SEBT scores. DESIGN: Case-control. SETTING: Controlled laboratory. PARTICIPANTS: A total of 36 physically active adults, 18 with history of unilateral CAI and 18 without history of ankle injury, were enrolled in the study. CAI subjects were identified using the Identification of Functional Ankle Instability questionnaire. INTERVENTIONS: The DLBT and the SEBT were performed in a randomized order on a randomly selected limb in CAI and healthy subjects. MAIN OUTCOME MEASURES: Time taken to complete the DLBT and the reach distances performed on the SEBT were compared between the CAI and the healthy subjects. RESULTS: There were no statistically significant differences (P < .05) in SEBT reach distances between groups. The DLBT time was greater (P < .01) for unstable ankles compared with the stable ankle. The authors found no correlation (P > .05) between DLBT time and any of the SEBT reach distances suggesting that the DLBT provides unique information in the assessment of patients with CAI. CONCLUSION: The DLBT challenges the ability to maintain postural control in CAI subjects differently than the SEBT. There is a need of more dynamic balance assessment tools that are functional and clinically relevant.

Application of a Preventive Training Program Implementation Framework to Youth Soccer and Basketball Organizations.

CONTEXT: Preventive training programs (PTPs) can reduce injury rates and improve neuromuscular control and sport performance. However, PTPs must be implemented correctly and consistently over time for athletes to benefit. Coaches represent the best long-term option for implementing PTPs. Youth athletes are at the optimal age for developing good habits before maturation. Although frameworks have been proposed to guide implementation efforts, little is known regarding the feasibility and real-world context of PTP implementation at the youth sport level. OBJECTIVE: To evaluate the application of the 7-Step framework for promoting implementation of a preseason PTP workshop. DESIGN: Descriptive epidemiology study. SETTING: Youth soccer and basketball organizations. PATIENTS OR OTHER PARTICIPANTS: Organizations with at least 1 team of athletes aged 8 to 14 years were invited to participate in a free preseason coaches' education workshop on PTP implementation. INTERVENTION(S): The 7-Step framework was used to guide PTP education and implementation for each organization. Personnel at organizations that agreed to participate attended a single preseason workshop for coaches. Research staff were available as a resource throughout the season but did not actively implement or monitor the PTPs. MAIN OUTCOME MEASURE(S): Retrospective evaluation of each organization's completion of steps 1 through 5 of the 7-Step framework. RESULTS: A total of 62 youth soccer (n = 40) and basketball (n = 22) organizations were invited to participate. Twelve organizations completed steps 1 through 4 and steps 5a through 5d. The highest drop-off rate occurred during step 1, "Establishing Administrative Support." No organization completed all components of steps 1 through 5. CONCLUSIONS: To better understand how to successfully promote PTP adoption, we must identify the implementation steps that may present the most challenges. Because the highest drop-off rate was seen during the initial step, establishing administrative support and strengthening initial engagement are necessary to improve PTP implementation.

Emergency Action Planning in Secondary School Athletics: A Comprehensive Evaluation of Current Adoption of Best Practice Standards.

CONTEXT: Emergency action plans (EAPs) are policies that improve response times and ensure access to emergency equipment for the management of patients with acute injuries and medical conditions, yet the extent to which EAP standards are adopted and implemented is unknown. OBJECTIVE: To describe the extent of EAP adoption and implementation in secondary school (SS) athletics with athletic trainer (AT) services in the United States. DESIGN: Cross-sectional study. SETTING: Web-based questionnaire. PATIENTS OR OTHER PARTICIPANTS: A national sample of ATs (n = 9642) was invited to participate in a Web-based questionnaire. MAIN OUTCOME MEASURE(S): Twelve components of EAP minimum best practices were derived from the "National Athletic Trainers' Association (NATA) Position Statement: Emergency Planning in Athletics." Emergency action plan components were analyzed using descriptive statistics with 95% confidence intervals (CIs) around proportions. Contingency tables (2 × 2) were used to calculate odds ratios (with 95% CIs) to assess adoption of the components (dichotomized as yes or no), employment factors (eg, full time versus part time, employed by clinic/district), and access to emergency equipment. RESULTS: The response rate for the questionnaire was 13.2% (n = 1273). A majority of ATs (89.1%) reported having an EAP; however, only 9.9% described implementing all 12 components cited in the NATA position statement. Athletic trainers stated that they created the EAP in 62.8% (95% CI = 60.1%, 65.4%) of schools with an EAP. Athletic trainers employed full time were at greater odds of adopting 9 or more components of the EAP compared with ATs employed part time (odds ratio = 2.42 [95% CI = 1.66, 3.53]). A total of 85.7% of ATs noted access to an automated external defibrillator. CONCLUSIONS: Although a majority of SSs had EAPs, the EAPs were often incomplete and lacked the necessary components for full compliance with the NATA position statement. These findings demonstrate the need for efforts to promote the adoption and implementation of comprehensive EAPs in SS athletics.

A Growing Consensus for Change in Interpretation of Clinical Research Evidence.

CONTEXT: The paradigm of evidence-based practice (EBP) is well established among the health care professions, but perspectives on the best methods for acquiring, analyzing, appraising, and using research evidence are evolving. BACKGROUND: The EBP paradigm has shifted away from a hierarchy of research-evidence quality to recognize that multiple research methods can yield evidence to guide clinicians and patients through a decision-making process. Whereas the "frequentist" approach to data interpretation through hypothesis testing has been the dominant analytical method used by and taught to athletic training students and scholars, this approach is not optimal for integrating evidence into routine clinical practice. Moreover, the dichotomy of rejecting, or failing to reject, a null hypothesis is inconsistent with the Bayesian-like clinical decision-making process that skilled health care providers intuitively use. We propose that data derived from multiple research methods can be best interpreted by reporting a credible lower limit that represents the smallest treatment effect at a specified level of certainty, which should be judged in relation to the smallest effect considered to be clinically meaningful. Such an approach can provide a quantifiable estimate of certainty that an individual patient needs follow-up attention to prevent an adverse outcome or that a meaningful level of therapeutic benefit will be derived from a given intervention. CONCLUSIONS: The practice of athletic training will be influenced by the evolution of the EBP paradigm. Contemporary practice will require clinicians to expand their critical-appraisal skills to effectively integrate the results derived from clinical research into the care of individual patients. Proper interpretation of a credible lower limit value for a magnitude ratio has the potential to increase the likelihood of favorable patient outcomes, thereby advancing the practice of evidence-based athletic training.

Implications of Thoracic Epidural Analgesia on Hospital Charges in Rib Fracture Patients.

Objective: Rib fractures are present in more than 150,000 patients admitted to US trauma centers each year. Those who fracture two or more ribs are typically treated with oral analgesic drugs and are discharged with few complications. The cost of this care generally reflects its brevity. When a patient fractures three or more ribs, there is an elevated risk of complication. In response, treatments are often broadened and their durations prolonged; this affects cost. While health, function, and survival have been widely explored, patient billing has not. Thus, we evaluated the financial implications of one mode of treatment for patients with rib fractures: thoracic epidural analgesia (TEA). Methods: We retrospectively analyzed the registry of a level II trauma center. All patients who fractured one or more ribs (n = 1,344) were considered; 382 of those patients were not candidates for epidural placement and were eliminated from analyses. Epidural placement was determined by individual clinicians. We used multiple linear regressions to determine predictors of cost. Results: After eliminating patients who were not eligible to receive TEA, the average patient bill was $59,123 ($10,631 per day of treatment). The administration of TEA predicted a 25% reduction in total billing (99% CI = -$21,429.55- -$7,794.66) and a 24% reduction in per-day billing (99% CI = -$3,745.99- -$1,276.14). Conclusions: Patients who received TEA were more severely injured and required longer treatments; controlling for these variables, the use of TEA associated with reductions in the cost of receiving care. From an administrative and insurance perspective, more frequent reliance on TEA may be indicated.

Validation of the Professional Identity and Values Scale Among an Athletic Trainer Population.

CONTEXT: Forming a professional identity is a process by which an individual achieves an awareness of his or her own self-concept in the context of the profession. Identity in relation to an individual's profession includes the ability to articulate one's role as a professional and professional philosophy. Professional identity has been studied extensively in other fields, but currently no professional identity scales have been validated within the athletic training profession. OBJECTIVE: To validate the Professional Identity and Values Scale (PIVS) among an athletic trainer population. DESIGN: Cross-sectional study. SETTING: Web-based questionnaire. PATIENTS OR OTHER PARTICIPANTS: Athletic trainers employed in National Collegiate Athletic Association Division I, II, III, or National Association of Intercollegiate Athletics colleges or universities (n = 299, 56.5% female, 43.5% male). The average age of the participants was 33.6 ± 8.3 years, and they had 10.3 ± 7.6 years of experience. MAIN OUTCOME MEASURE(S): Participants were asked to complete a demographic questionnaire and the 32-item PIVS. The variables included demographics and the PIVS (Professional Orientation and Values subscale [18 items] and the Professional Development subscale [14 items]). RESULTS: Exploratory factor analysis reduced the survey from 32 to 20 items and revealed 6 factors. Three factors emerged from the Professional Development subscale and emphasized professional insecurities during the early career stages, the importance of mentors during the intermediate stages, and self-confidence and awareness during the later stages of professional development. An additional 3 factors emerged from the Professional Orientation and Values subscale: (1) patient care and advocacy, (2) professional engagement and collaboration, and (3) personal wellness and values. A Cronbach α of 0.80 indicated good internal consistency. CONCLUSIONS: A modified PIVS is a valid and reliable measure of professional identity among athletic trainers employed in the collegiate setting.

Multilevel Examination of Job Satisfaction and Career Intentions of Collegiate Athletic Trainers: A Quantitative Approach.

CONTEXT: Recent employment data from collegiate athletic training settings have demonstrated departure trends among men and women. These trends have been hypothesized to be related to work-life balance. However, work-life balance is only 1 aspect of a myriad of factors. Due to the complex nature of the work-life interface, a multilevel examination is needed to better understand the precipitators of departure. OBJECTIVE: To quantitatively examine factors that may influence collegiate athletic trainers' (ATs') job satisfaction and career intentions via a multilevel examination of the work-life interface. DESIGN: Cross-sectional study. SETTING: Web-based questionnaire. PATIENTS OR OTHER PARTICIPANTS: Athletic trainers employed in National Collegiate Athletic Association Division I, II, or III or National Association of Intercollegiate Athletics colleges or universities (N = 299: 56.5% female, 43.5% male). The average age of participants was 33.6 ± 8.3 years, and their average experience was 10.3 ± 7.6 years. DATA COLLECTION AND ANALYSIS: Participants responded to an online questionnaire consisting of demographic questions, 9 Likert-scale surveys, and open-ended questions. Job-satisfaction Scores (JSSs) and intention-to-leave scores (ITLSs) served as the dependent variables and factors from individual, organizational, and sociocultural levels were the independent variables. Hierarchical regression analysis was run to determine the predictability of factors. RESULTS: No sex differences in ITLS or JSS were found in our sample. Independent variables explained 68.5% of the variance in JSS and 28.8% of the variance in ITLS. Additions of factor levels increased the percentage of explained variance in both scores. CONCLUSIONS: A combination of individual-, organizational-, and sociocultural-level factors was able to best predict JSS and ITLS among collegiate ATs.

Coach-led preventive training program in youth soccer players improves movement technique.

Long-term implementation of preventive training programs (PTP) in youth sport requires coach involvement. However, the optimal training of coaches to effectively implement a PTP remains unknown. It is also unknown if the benefits of PTP can be enhanced with multiple sport seasons of exposure. OBJECTIVES: To evaluate the influence of prior PTP exposure on movement technique in youth soccer players after completing a coach-led PTP. DESIGN: Cluster-randomized controlled trial. METHODS: Twelve youth soccer teams (n=89; age range 8-14 years) were divided into groups with (Experience (EXP); 6 teams [n=18 females, n=25 males]) and without (Novice (NOV); 6 teams [n=30 females, n=16 males]) previous professional-led PTP experience. The coaches and players of the EXP teams were exposed to an eight-week professional-led PTP before the coach-led PTP. EXP and NOV coaches attended the educational workshop prior to implementing the coach-led PTP. The Landing Error Scoring System (LESS) was used to evaluate movement technique. RESULTS: Both groups improved LESS scores over time (mean difference±SD [post-pre]=-0.8±0.2, 95%CI [-1.2, -0.4], p=0.0001). Of the 64 participants classified as high risk for injury (LESS ≥5) prior to PTP implementation, a greater proportion of EXP (n=14) compared to NOV (n=7) participants changed risk classification from high to low (LESSΔ≥1 and LESS <5; p=0.03). CONCLUSIONS: Our PTP enhanced movement technique regardless of PTP experience, but the benefits of the PTP impacted a proportionally greater number of players with previous PTP experience supporting continued PTP implementation. Coaches effectively implemented an exercise-based PTP after attending a training workshop regardless of previous PTP experience.

Effects of heat acclimation on hand cooling efficacy following exercise in the heat.

This study examined the separate and combined effects of heat acclimation and hand cooling on post-exercise cooling rates following bouts of exercise in the heat. Seventeen non-heat acclimated (NHA) males (mean ± SE; age, 23 ± 1 y; mass, 75.30 ± 2.27 kg; maximal oxygen consumption [VO2 max], 54.1 ± 1.3 ml·kg-1·min-1) completed 2 heat stress tests (HST) when NHA, then 10 days of heat acclimation, then 2 HST once heat acclimated (HA) in an environmental chamber (40°C; 40%RH). HSTs were 2 60-min bouts of treadmill exercise (45% VO2 max; 2% grade) each followed by 10 min of hand cooling (C) or no cooling (NC). Heat acclimation sessions were 90-240 min of treadmill or stationary bike exercise (60-80% VO2 max). Repeated measures ANOVA with Fishers LSD post hoc (α < 0.05) identified differences. When NHA, C (0.020 ± 0.003°C·min-1) had a greater cooling rate than NC (0.013 ± 0.003°C·min-1) (mean difference [95%CI]; 0.007°C [0.001,0.013], P = 0.035). Once HA, C (0.021 ± 0.002°C·min-1) was similar to NC (0.025 ± 0.002°C·min-1) (0.004°C [-0.003,0.011], P = 0.216). Hand cooling when HA (0.021 ± 0.002°C·min-1) was similar to when NHA (0.020 ± 0.003°C·min-1) (P = 0.77). In conclusion, when NHA, C provided greater cooling rates than NC. Once HA, C and NC provided similar cooling rates.

Improved Outcomes Associated with the Liberal Use of Thoracic Epidural Analgesia in Patients with Rib Fractures.

OBJECTIVE: Each year, more than 150,000 patients with rib fractures are admitted to US trauma centers; as many as 10% die. Effective pain control is critical to survival. One way to manage pain is thoracic epidural analgesia. If this treatment reduces mortality, more frequent use may be indicated. METHODS: We analyzed the patient registry of a level II trauma center. All patients admitted with one or more rib fractures (N = 1,347) were considered. Patients who were not candidates for epidural analgesia (N = 382) were eliminated. Mortality was assessed with binary logistic regressions. RESULTS: Across the total population, mortality was 6.7%; incidence of pneumonia was 11.1%; mechanical ventilation was required in 23.8% of patients, for an average duration of 10.0 days; average stay in the hospital was 7.7 nights; and 49.7% of patients were admitted to the ICU for an average of 7.2 nights. Epidural analgesia was administered to 18.4% of patients. After matching samples for candidacy, patients who received epidurals were 3.7 years older, fractured 2.6 more ribs, had higher injury severity scores, and were more likely to present with bilateral fractures, flail segments, pulmonary contusions, hemothoraces, and pneumothoraces. Despite greater injury severity, mortality among these patients was lower (0.5%) than those who received alternative care (1.9%). Controlling for age, injury severity, and use of mechanical ventilation, epidural analgesia predicted a 97% reduction in mortality. CONCLUSION: Thoracic epidural analgesia associates with reduced mortality in rib fracture patients. Better care of this population is likely to be facilitated by more frequent reliance on this treatment.

Female adolescent athletes' attitudes and perspectives on injury prevention programs.

OBJECTIVES: To examine what factors influence a high school female athlete's stated willingness to perform a lower extremity injury prevention program (IPP). A secondary aim was to examine if a participant's stated willingness affected her compliance with an IPP. DESIGN: Repeated measures. METHODS: We surveyed high school female field hockey, soccer and volleyball athletes before and after a season-long IPP warm-up intervention. Participants completed the Injury Prevention Program Attitude Survey (IPPAS), a paper and pencil survey utilizing Likert-style and open-ended questions. It was used to assess the athletes' willingness to perform an IPP if the data proved the player would experience improved performance, fewer injuries and risk factors, what outside factors influence their willingness to perform an IPP, who they would feel comfortable leading their team in an IPP, and what they believe an IPP can improve. RESULTS: Participants responded that they were willing to perform an IPP if data proved that they would have fewer injury risk factors (p≤0.001) and be less likely to suffer an ACL injury (p<0.001). Improved sport performance did not play a role in participants' willingness to perform an IPP. Before and after the warm-up intervention, participants stated that stretching, strengthening, and cardiovascular activity should be included in an IPP. Participants' stated willingness and beliefs prior to the intervention did not appear to affect their compliance. CONCLUSIONS: Female adolescent athletes are willing to perform IPPs if data indicated that they would have fewer injury risk factors and suffer fewer ACL and leg injuries.

Achilles Tendon Properties of Minimalist and Traditionally Shod Runners.

CONTEXT: Tendon adapts to load through alterations in its composition and mechanical properties. Mechanical adaptation to increased load often involves increases in cross-sectional area (CSA), stiffness, and modulus. Runners exhibit these adaptations. OBJECTIVE: To determine if runners wearing minimalist shoes had larger and stiffer Achilles tendons (AT) than traditionally shod runners. DESIGN: Cross-sectional study of well-trained, traditionally and minimally shod runners. SETTING: Laboratory assessment of trained runners. PARTICIPANTS: 23 men (11 traditional, 12 minimalist) and 8 women (6 traditional, 2 minimalist). Runners wearing minimalist shoes had 4.2 ± 1.6 y of training experience in minimalist shoes. MAIN OUTCOME MEASURES: The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force-elongation curve and its derivatives. RESULTS: Minimalist runners had a greater CSA: mean difference (MD) = 9.2 mm2, stiffness (MD = 268.1 N/mm), and modulus (MD = 202.9 MPa). ATs of minimalist runners experienced greater stress (MD 8.6 N/mm2) during maximal voluntary isometric contraction of the plantar-flexor muscles due to greater force of contraction (MD 798.9 N). CONCLUSION: The AT in minimalist runners adapts by increasing size, stiffness, and modulus, which is consistent with our understanding of mechanical adaptation of tendon to increased loading. Increased stress to the AT likely requires a slow transition to minimalist running to allow the AT to adapt without evidence of injury.

Achilles Tendon Adaptation During Transition to a Minimalist Running Style.

CONTEXT: Achilles tendons (ATs) adapt to increased loading generated by long-term adoption of a minimalist shoe running style. There may be difference in the chronology and extent of adaptation between the sexes. OBJECTIVE: To learn the chronology of AT adaptations in female and male runners who transitioned to a minimalist running style through a planned, progressive 12-wk transition program. DESIGN: Prospective cohort study of well-trained, traditionally shod runners who transitioned to minimalist shoe running. SETTING: Repeated laboratory assessment at baseline and 3, 12, and 24 wk after initiating transition program. PARTICIPANTS: Fifteen women and 7 men (of 29 enrolled) completed the study. MAIN OUTCOME MEASURES: The authors used diagnostic ultrasound and isokinetic dynamometry to generate a force elongation curve and its derivatives at each time point. RESULTS: Greater adaptations were observed in men than in women, with men generating more force and having greater increases in CSA, stiffness, and Young's modulus and less elongation after 12 wk of training. CONCLUSION: Men demonstrated changes in AT properties that were consistent with increased loading of the triceps surae during exercise. The women demonstrated far smaller changes. Further investigation is warranted to understand when adaptations may occur in women and the implications of altered AT mechanical properties for performance and injury risk.

Electromyographical and Perceptual Responses to Different Resistance Intensities in a Squat Protocol: Does Performing Sets to Failure With Light Loads Produce the Same Activity?

This investigation examined peak motor unit activity during sets that differed in resistance (50, 70, or 90% 1 repetition maximum [1RM]). Ten resistance-trained men (age, 23 ± 3 years; height, 187 ± 7 cm; body mass, 91.5 ± 6.9 kg; squat 1RM, 141 ± 28 kg) were assessed by electromyography (EMG) on the vastus lateralis and vastus medialis muscles in a randomized within-subject experiment consisting of 2 test visits: a drop-set day and a single-set day using only the 50% of 1RM intensity performed to failure. At the start of each day, subjects performed 2 submaximal repetition sets (50% 1RM × 10 repetitions and 70% 1RM × 7 repetitions). On the drop-set day, subjects performed 3 consecutive maximal repetition sets at 90%, 70%, and 50% 1RM to failure with no rest periods in between. On the single-set day, subjects performed a maximal repetition set at 50% 1RM to failure. Overall, the maximal repetition sets to failure at 50% and 70% 1RM resulted in higher peak EMG amplitude than during submaximal repetition sets with the same resistance. However, peak EMG amplitude was significantly (p ≤ 0.05) greater in the maximal 90% 1RM set than all other sets performed. When sets were performed to failure, ratings of perceived exertion (CR-10) did not differ over the intensity range of loads and suggests that perception is not capable of accurately detecting the actual amount of motor unit activation. The results of this investigation indicate that using higher external resistance is a more effective means of increasing motor unit activity than increasing the number of repetitions performed with lighter weights even when the end point is muscular failure. Accordingly, previous recommendations for the use of heavier loads during resistance training programs to stimulate the maximal development of strength and hypertrophy are further supported.