Limited passive hamstring flexibility might affect kinematics, performance, and injury risk during running. Pre-activity static straight-leg raise stretching often is used to gain passive hamstring flexibility. To investigate the acute effects of a single session of passive hamstring stretching on pelvic, hip, and knee kinematics during the swing phase of running. Randomized controlled clinical trial. Biomechanics research laboratory. Thirty-four male (age = 21.2 ± 1.4 years) and female (age = 21.3±2.0 years) recreational athletes. Participants performed treadmill running pretests and posttests at 70% of their age-predicted maximum heart rate. Pelvis, hip, and knee joint angles during the swing phase of 5 consecutive gait cycles were collected using a motion analysis system. Right and left hamstrings of the intervention group participants were passively stretched 3 times for 30 seconds in random order immediately after the pretest. Control group participants performed no stretching or movement between running sessions. Six 2-way analyses of variance to determine joint angle differences between groups at maximum hip flexion and maximum knee extension with an α level of .008. Flexibility increased between pretest and post-test in all participants (F1,30 = 80.61, P<.001). Anterior pelvic tilt (F1,30 = 0.73, P=.40), hip flexion (F1,30 = 2.44, P=.13), and knee extension (F1,30 = 0.06, P=.80) at maximum hip flexion were similar between groups throughout testing. Anterior pelvic tilt (F1,30 = 0.69, P=.41), hip flexion (F1,30 = 0.23, P=.64), and knee extension (F1,30 = 3.38, P=.62) at maximum knee extension were similar between groups throughout testing. Men demonstrated greater anterior pelvic tilt than women at maximum knee extension (F1,30 = 13.62, P=.001). A single session of 3 straight-leg raise hamstring stretches did not change pelvis, hip, or knee running kinematics.Context:
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Lower extremity overuse injuries are associated with gluteus medius (GMed) weakness. Understanding the activation of muscles about the hip during strengthening exercises is important for rehabilitation. To compare the electromyographic activity produced by the gluteus medius (GMed), tensor fascia latae (TFL), anterior hip flexors (AHF), and gluteus maximus (GMax) during 3 hip-strengthening exercises: hip abduction (ABD), hip abduction with external rotation (ABD-ER), and clamshell (CLAM) exercises. Controlled laboratory study. Laboratory. Twenty healthy runners (9 men, 11 women; age = 25.45 ± 5.80 years, height = 1.71 ± 0.07 m, mass = 64.43 ± 7.75 kg) participated. A weight equal to 5% body mass was affixed to the ankle for the ABD and ABD-ER exercises, and an equivalent load was affixed for the CLAM exercise. A pressure biofeedback unit was placed beneath the trunk to provide positional feedback. Surface electromyography (root mean square normalized to maximal voluntary isometric contraction) was recorded over the GMed, TFL, AHF, and GMax. Three 1-way, repeated-measures analyses of variance indicated differences for muscle activity among the ABD (F3,57 = 25.903, P<.001), ABD-ER (F3,57 = 10.458, P<.001), and CLAM (F3,57 = 4.640, P=.006) exercises. For the ABD exercise, the GMed (70.1 ± 29.9%), TFL (54.3 ± 19.1%), and AHF (28.2 ± 21.5%) differed in muscle activity. The GMax (25.3 ± 24.6%) was less active than the GMed and TFL but was not different from the AHF. For the ABD-ER exercise, the TFL (70.9 ± 17.2%) was more active than the AHF (54.3 ± 24.8%), GMed (53.03 ± 28.4%), and GMax (31.7 ± 24.1 %). For the CLAM exercise, the AHF (54.2 ± 25.2%) was more active than the TFL (34.4 ± 20.1%) and GMed (32.6 ± 16.9%) but was not different from the GMax (34.2 ± 24.8%). The ABD exercise is preferred if targeted activation of the GMed is a goal. Activation of the other muscles in the ABD-ER and CLAM exercises exceeded that of GMed, which might indicate the exercises are less appropriate when the primary goal is the GMed activation and strengthening.Context:
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Lumbopelvic Joint Manipulation and Quadriceps Activation of People With Patellofemoral Pain Syndrome
Quadriceps weakness and inhibition are impairments associated with patellofemoral pain syndrome (PFPS). Lumbopelvic joint manipulation has been shown to improve quadriceps force output and inhibition, but the duration of the effect is unknown. To determine whether quadriceps strength and activation are increased and maintained for 1 hour after high-grade or low-grade joint mobilization or manipulation applied at the lumbopelvic region in people with PFPS. Randomized controlled clinical trial. University laboratory. Forty-eight people with PFPS (age = 24.6±8.9 years, height = 174.3 ± 11.2 cm, mass = 78.4 ± 16.8 kg) participated. Participants were randomized to 1 of 3 groups: lumbopelvic joint manipulation (grade V), side-lying lumbar midrange flexion and extension passive range of motion (grade II) for 1 minute, or prone extension on the elbows for 3 minutes. Quadriceps force and activation were measured using the burst superimposition technique during a seated isometric knee extension task. A 2-way repeated-measures analysis of variance was performed to compare changes in quadriceps force and activation among groups over time (before intervention and at 0, 20, 40, and 60 minutes after intervention). We found no differences in quadriceps force output (F5,33,101,18 = 0.65, P = .67) or central activation ratio (F4.84,92.03 = 0.38, P= .86) values among groups after intervention. When groups were pooled, we found differences across time for quadriceps force (F2.66,101.18 = 5.03, P = .004) and activation (F2.42,92.03 = 3.85, P = .02). Quadriceps force was not different at 0 minutes after intervention (t40 = 1.68, P = .10), but it decreased at 20 (t40 = 2.16, P = .04), 40 (t40 = 2.87, P = .01) and 60 (t40 = 3.04, P = .004) minutes after intervention. All groups demonstrated decreased quadriceps activation at 0 minutes after intervention (t40 = 4.17, P <.001), but subsequent measures were not different from preintervention levels (t40 range, 1.53–1.83, P >.09). Interventions directed at the lumbopelvic region did not have immediate effects on quadriceps force output or activation. Muscle fatigue might have contributed to decreased force output and activation over 1 hour of testing.Context:
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Altered neuromuscular control strategies during fatigue probably contribute to the increased incidence of non-contact anterior cruciate ligament injuries in female athletes. To determine biomechanical differences between 2 fatigue protocols (slow linear oxidative fatigue protocol [SLO-FP] and functional agility short-term fatigue protocol [FAST-FP]) when performing a running-stop-jump task. Controlled laboratory study. Laboratory. A convenience sample of 15 female soccer players (age = 19.2 ±0.8 years, height = 1.67±0.05m, mass = 61.7 + 8.1 kg) without injury participated. Five successful trials of a running–stop-jump task were obtained prefatigue and postfatigue during the 2 protocols. For the SLO-FP, a peak oxygen consumption (V˙o2peak) test was conducted before the fatigue protocol. Five minutes after the conclusion of the V˙o2peak test, participants started the fatigue protocol by performing a 30-minute interval run. The FAST-FP consisted of 4 sets of a functional circuit. Repeated 2 (fatigue protocol) × 2 (time) analyses of variance were conducted to assess differences between the 2 protocols and time (prefatigue, postfatigue). Kinematic and kinetic measures of the hip and knee were obtained at different times while participants performed both protocols during prefatigue and postfatigue. Internal adduction moment at initial contact (IC) was greater during FAST-FP (0.064 ±0.09 Nm/kgm) than SLO-FP (0.024±0.06 Nm/kgm) (F1,14 = 5.610, P=.03). At IC, participants had less hip flexion postfatigue (44.7°±8.1°) than prefatigue (50.1°±9.5°) (F1,14 = 16.229, P=.001). At peak vertical ground reaction force, participants had less hip flexion postfatigue (44.7°±8.4°) than prefatigue (50.4°±10.3°) (F1,14 = 17.026, P=.001). At peak vertical ground reaction force, participants had less knee flexion postfatigue (−35.9°±6.5°) than prefatigue (−38.8°±5.03°) (F1,14 = 11.537, P=.001). Our results demonstrated a more erect landing posture due to a decrease in hip and knee flexion angles in the postfatigue condition. The changes were similar between protocols; however, the FAST-FP was a clinically applicable 5-minute protocol, whereas the SLO-FP lasted approximately 45 minutes.Context:
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Health care providers must be prepared to manage all potential spine injuries as if they are unstable. Therefore, most sport teams devote resources to training for sideline cervical spine (C-spine) emergencies. To determine (1) how accurately rescuers and simulated patients can assess motion during C-spine stabilization practice and (2) whether providing performance feedback to rescuers influences their choice of stabilization technique. Crossover study. Training studio. Athletic trainers, athletic therapists, and physiotherapists experienced at managing suspected C-spine injuries. Twelve lead rescuers (at the patient's head) performed both the head-squeeze and trap-squeeze C-spine stabilization maneuvers during 4 test scenarios: lift-and-slide and log-roll placement on a spine board and confused patient trying to sit up or rotate the head. Interrater reliability between rescuer and simulated patient quality scores for subjective evaluation of C-spine stabilization during trials (0 = best, 10 = worst), correlation between rescuers' quality scores and objective measures of motion with inertial measurement units, and frequency of change in preference for the head-squeeze versus trap-squeeze maneuver. Although the weighted κ value for interrater reliability was acceptable (0.71–0.74), scores varied by 2 points or more between rescuers and simulated patients for approximately 10% to 15% of trials. Rescuers' scores correlated with objective measures, but variability was large: 38% of trials scored as 0 or 1 by the rescuer involved more than 10° of motion in at least 1 direction. Feedback did not affect the preference for the lift-and-slide placement. For the log-roll placement, 6 of 8 participants who preferred the head squeeze at baseline preferred the trap squeeze after feedback. For the confused patient, 5 of 5 participants initially preferred the head squeeze but preferred the trap squeeze after feedback. Rescuers and simulated patients could not adequately assess performance during C-spine stabilization maneuvers without objective measures. Providing immediate feedback in this context is a promising tool for changing behavior preferences and improving training.Context:
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The reliability of clinical techniques to quantify thoracic spine rotation range of motion (ROM) has not been evaluated. To determine the intratester and intertester reliability of 5 thoracic rotation measurement techniques. Descriptive laboratory study. University research laboratory. Forty-six healthy volunteers (age = 23.6±4.3 years, height = 171.0±9.6 cm, mass = 71.4 ±16.7 kg). We tested 5 thoracic rotation ROM techniques over 2 days: seated rotation (bar in back and front), half-kneeling rotation (bar in back and front), and lumbar-locked rotation. On day 1, 2 examiners obtained 2 sets of measurements (sessions 1, 2) to determine the within-session intertester reliability and within-day intratester reliability. A single examiner obtained measurements on day 2 (session 3) to determine the intratester reliability between days. Each technique was performed 3 times per side, and averages were used for data analysis. Reliability was determined using intraclass correlation coefficients, standard error of measurement (SEM), and minimal detectable change (MDC). Differences between raters during session 1 were determined using paired t tests. Within-session intertester reliability estimates ranged from 0.85 to 0.94. Ranges for the SEM were 1.0° to 2.3° and for the MDC were 2.8° to 6.3°. No differences were seen between examiners during session 1 for seated rotation (bar in front, both sides), half-kneeling rotation (bar in front, left side), or the lumbar locked position (both sides) (all values of P > .05). Within-day intratester reliability estimates ranged from 0.86 to 0.95. Ranges for the SEM were 0.8° to 2.1° and for the MDC were 2.1 ° to 5. 9°. Between-days intratester reliability estimates ranged from 0.84 to 0.91. Ranges for the SEM were 1.4° to 2.0° and for the MDC were 3.9° to 5.6°. All techniques had good reliability and low levels of measurement error. The seated rotation, bar in front, and lumbar-locked rotation tests may be used reliably when more than 1 examiner is obtaining measurements.Context:
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Many active people finish exercise hypohydrated, so effective rehydration after exercise is an important consideration. To determine the effects of a rehydration solution containing whey protein isolate on fluid balance after exercise-induced dehydration. Randomized controlled clinical trial. University research laboratory. Twelve healthy men (age = 21 ± 1 years, height = 1.82 ± 0.08m, mass = 82.71 ± 10.31 kg) participated. Participants reduced body mass by 1.86% ± 0.07% after intermittent exercise in the heat and re-hydrated with a volume of drink in liters equivalent to 1.5 times their body mass loss in kilograms of a solution of either 65 g/L carbohydrate (trial C) or 50 g/L carbohydrate and 15 g/L whey protein isolate (trial CP). Solutions were matched for energy density and electrolyte content. Urine samples were collected before and after exercise and for 4 hours after rehydration. We measured urine volume, drink retention, net fluid balance, urine osmolality, and subjective responses. Drink retention was calculated as the difference between the volume of drink ingested and urine produced. Net fluid balance was calculated from fluid gained through drink ingestion and fluid lost through sweat and urine production. Total cumulative urine output after rehydration was not different between trial C (1173 ± 481 mL) and trial CP (1180 ± 330 mL) (F1 = 0.002, P = .96), and drink retention during the study also was not different between trial C (50% ± 18%) and trial CP (49% ± 13%) (t11 = −0.159, P = .88). At the end of the study, net fluid balance was negative compared with base-line for trial C (−432 ± 436 mL) (t11 = 3.433, P = .03) and trial CP (−432 ± 302 mL) (t11 = 4.958, P = .003). When matched for energy density and electrolyte content, a solution of carbohydrate and whey protein isolate neither increased nor decreased rehydration compared with a solution of carbohydrate.Context:
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Few population-based studies have examined the incidence of meniscal injuries, and limited information is available on the influence of patient's demographic and occupational factors. To examine the incidence of meniscal injuries and the influence of demographic and occupational factors among active-duty US service members between 1998 and 2006. Cohort study. Using the International Classification of Diseases (9th revision) codes 836.0 (medial meniscus), 836.1 (lateral meniscus), and 836.2 (meniscus unspecified), we extracted injury data from the Defense Medical Surveillance System to identify all acute meniscal injuries among active-duty military personnel. Active-duty military personnel serving in all branches of military service during the study period. Incidence rate (IR) per 1000 person-years at risk and crude and adjusted rates by strata for age, sex, race, rank, and service. During the study period, 100201 acute meniscal injuries and 12115606 person-years at risk for injury were documented. The overall IR was 8.27 (95% confidence interval [CI] = 8.22, 8.32) per 1000 person-years. Main effects were noted for all demographic and occupational variables (P< .001), indicating that age, sex, race, rank, and service were associated with the incidence of meniscal injuries. Men were almost 20% more likely to experience an acute meniscal injury than were women (incidence rate ratio = 1.18, 95% CI = 1.15, 1.20). The rate of meniscal injury increased with age; those older than 40 years of age experienced injuries more than 4 times as often as those under 20 years of age (incidence rate ratio = 4.25,95% CI = 4.08, 4.42). The incidence of meniscal injury was sub-stantially higher in this study than in previously reported studies. Male sex, increasing age, and service in the Army or Marine Corps were factors associated with meniscal injuries.Context:
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The female athlete triad describes the interrelatedness of energy availability, menstrual function, and bone density. Although associations between triad components and musculoskeletal injury (INJ) have been reported in collegiate athletes, limited information exists about menstrual irregularity (MI) and INJ in the high school population. To determine the prevalence of and relationship between MI and INJ in high school athletes. Cross-sectional study. High schools. The sample consisted of 249 female athletes from 3 high schools who competed in 33 interscholastic, school-sponsored sport teams, dance teams, and cheerleading or pom-pon squad during the 2006–2007 school year. Each athlete remained on the roster throughout the season. Participants completed a survey regarding injury type, number of days of sport participation missed, and menstrual history in the past year. The prevalences of MI and INJ were 19.7% and 63.1%, respectively. Athletes who reported MI sustained a higher percentage of severe injuries (missing ≥22 days of practice or competition) than did athletes who reported normal menses. Although the trend was not significant, athletes with MI were almost 3 times more likely to sustain an injury resulting in 7 or more days of time lost from sport (odds ratio = 2.7, 95% confidence interval = 0.8, 8.8) than those who sustained an injury resulting in 7 or fewer days of time lost. The incidences of MI and INJ in this high school population during the study period were high. Athletes who reported MI sustained a higher percentage of severe injuries than did athletes who reported normal menses. Education programs to increase knowledge and improve management of MI and its potential effects on injury in female high school athletes are warranted.Context:
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Clinically, lowering of the medial longitudinal arch is believed to be closely related to rearfoot eversion. However, the relationship between arch height and rearfoot eversion during gait is unclear. (1) To examine the influence of 2 reference positions (weight-bearing neutral position [WBNP] and subtalar neutral position [STNP]) on maximum rearfoot eversion, tibial internal rotation, knee flexion, knee internal rotation, and dorsiflexion-plantar flexion of ankle joint measures during jogging and (2) to compare the relationships among static arch height, navicular drop, and the 2 maximum rearfoot eversion measures. Crossover study. Gait laboratory. Thirty-three volunteers between 18 and 40 years of age. Each participant stood on the treadmill in 2 static positions: WBNP and STNP. Kinematic data were obtained using a 10-camera motion analysis system (120 Hz) when participants jogged at 2.65 m/s on the treadmill in bare feet. Rearfoot and shank angular kinematics, navicular drop, and static arch height. Maximum rearfoot eversion was greater (WBNP: 4.03° ± 2.58°, STNP: 10.91° ± 5.34°) when STNP was the static reference (P < .001). A strong correlation was seen between maximum STNP eversion and navicular drop (r = 0.842) but not between WBNP and navicular drop (r = 0.216). Differences were noted in dorsiflexion and knee kinematics during gait between the static references; however, the effect sizes were low, and the mean differences were smaller than 2°, which was less than 5% of total excursion during gait. Using STNP rather than WBNP as the reference position affects estimates of frontal-plane rearfoot movement but not other ankle or knee motions in jogging.Context:
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Medical organizations have recommended that administrators, parents, and community leaders explore every opportunity to make interscholastic athletic programs safe for participation, including employing athletic trainers at practices and competitive events. To determine the overall level of medical services provided for secondary school-aged athletes at high school athletic events in a rural southern state, to evaluate the employment of athletic trainers in the provision of medical services in secondary schools, and to compare athletic training medical services provided at athletic events among schools of various sizes. Cross-sectional study. Questionnaires were sent to administrators at 199 secondary schools. A total of 144 administrators, including interscholastic athletic directors and school principals, from 199 secondary schools participated (72% response rate). Participants completed the Self-Appraisal Checklist for Health Supervision in Scholastic Athletic Programs from the American Academy of Pediatrics, which has been demonstrated to be valid and reliable. The Kruskal-Wallis and Mann-Whitney tests were used to measure differences in groups. We found differences in cumulative scores when measuring between institutional classifications (P≤.05). Cumulative scores for the Event Coverage section of the instrument ranged from 80.5 to 109.6 out of a total possible score of 126. We also found differences in several factors identified in the Event Coverage section (P≤.05). The number of coaching staff certified in cardiopulmonary resuscitation or first aid was minimal. Most schools did not have a plan for providing minimal emergency equipment, ice, or water for visiting teams. We found that 88% (n = 7) of the 8 essential Event Coverage components that the American Academy of Pediatrics deems important were not addressed by schools represented in our study.Context:
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To present recommendations for the prevention and screening, recognition, and treatment of the most common conditions resulting in sudden death in organized sports. Cardiac conditions, head injuries, neck injuries, exertional heat stroke, exertional sickling, asthma, and other factors (eg, lightning, diabetes) are the most common causes of death in athletes. These guidelines are intended to provide relevant information on preventing sudden death in sports and to give specific recommendations for certified athletic trainers and others participating in athletic health care.Objective:
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Reliability and Validity of the Functional Assessment of Neurocognition in Sport (FANS): A Paradigm Shift in Post-Concussion Return-to-Sport Decision-Making
Driving After Concussion: Clinical Measures Associated with Post-concussion
The role of shoulder posture in pitching mechanics and injury risk in high school baseball pitchers
Corticospinal Excitability during Standing and Its Association with Postural Control Following Acute Lateral Ankle Sprain.
The socio-economic cost of anterior cruciate ligament injuries and lateral ankle sprains in amateur football and basketball.
JAT eISSN: 1938-162X
JAT ISSN: 1062-6050
ATEJ ISSN: 1947-380X