Single joint kinematic alterations have been identified during gait in those with chronic ankle instability (CAI). The purpose of this study was to compare sagittal plane hip, knee, and ankle kinematics during walking in participants with and without CAI. Twelve individuals with CAI and 12 healthy individuals walked on a treadmill at 1.5 m/s. Three-dimensional kinematics were analyzed using mean ensemble curves and independent t tests. Participants with CAI demonstrated less lower extremity flexion during the absorption phase of stance and the limb placement phase of swing, which may have implications for limb placement at initial contact.
Matthew C. Hoch, David R. Mullineaux, Kyoungkyu Jeon and Patrick O. McKeon
Bente R. Jensen, Line Hovgaard-Hansen and Katrine L. Cappelen
Running on a lower-body positive-pressure (LBPP) treadmill allows effects of weight support on leg muscle activation to be assessed systematically, and has the potential to facilitate rehabilitation and prevent overloading. The aim was to study the effect of running with weight support on leg muscle activation and to estimate relative knee and ankle joint forces. Runners performed 6-min running sessions at 2.22 m/s and 3.33 m/s, at 100%, 80%, 60%, 40%, and 20% body weight (BW). Surface electromyography, ground reaction force, and running characteristics were measured. Relative knee and ankle joint forces were estimated. Leg muscles responded differently to unweighting during running, reflecting different relative contribution to propulsion and antigravity forces. At 20% BW, knee extensor EMGpeak decreased to 22% at 2.22 m/s and 28% at 3.33 m/s of 100% BW values. Plantar flexors decreased to 52% and 58% at 20% BW, while activity of biceps femoris muscle remained unchanged. Unweighting with LBPP reduced estimated joint force significantly although less than proportional to the degree of weight support (ankle).It was concluded that leg muscle activation adapted to the new biomechanical environment, and the effect of unweighting on estimated knee force was more pronounced than on ankle force.
Jennifer M. Medina McKeon, Patrick O. McKeon and Marjorie A. King
Kristen Couper Schellhase, Jennifer L. Plant and Carey E. Rothschild
Alicia M. Kissinger-Knox, Nicole J. Norheim, Denise S. Vagt, Kevin P. Mulligan and Frank M. Webbe
We compared two modes of ascertaining symptom information in baseline concussion testing with 754 NCAA Division II collegiate athletes. All athletes reported symptoms in both a face-to-face structured clinical interview using the SCAT3 symptom scale items and the similar symptom self-report scale in the computerized ImPACT test. Males reported significantly more symptoms and with greater severity during the interview compared to the computerized self-report. If males report symptoms according to a different format in posttrauma assessments than baseline, differences may reflect mode of testing and not change due to concussion.
Nathan Millikan, Dustin R. Grooms, Brett Hoffman and Janet E. Simon
Context: Functional tests are limited primarily by measuring only physical performance. However, athletes often multitask, and deal with complex visual-spatial processing while being engaged in physical activity. Objective: To present the development and reliability of 4 new neurocognitive single-leg hop tests that provide more ecological validity to test sport activity demands than previous functional return to sport testing. Design: Cross-sectional. Setting: Gymnasium. Participants: Twenty-two healthy participants (9 males and 13 females; 20.9 [2.5] y, 171.2 [11.7] cm, 70.3 [11.0] kg) were recruited. Interventions: Maximum distance (physical performance) and reaction time (cognitive performance) were measured for 3 of the neurocognitive hop tests all testing a different aspect of neurocognition (single-leg central-reaction hop—reaction time to 1 central stimulus, single-leg peripheral-reaction crossover hop—reaction time between 2 peripheral stimuli, and single-leg memory triple hop—reaction to memorized stimulus with distractor stimuli). Fastest time (physical performance) and reaction time (cognitive performance) were measured for the fourth neurocognitive hop test (single-leg pursuit 6m hop—requiring visual field tracking [pursuit] and spatial navigation). Main Outcome Measures: Intraclass correlation coefficients were calculated to assess reliability of the 4 new hop tests. Additionally, Bland–Altman plots and 1-sample t tests were conducted for each single-leg neurocognitive hop to evaluate any systematic changes. Results: Intraclass correlation coefficients based on day 1 and day 2 scores ranged from .87 to .98 for both legs for physical and cognitive performance. The Bland–Altman plots and 1-sample t tests (P > .05) indicated that all 4 single-leg neurocognitive hop tests did not change systematically. Conclusions: These data provide evidence that a neurocognitive component can be added to the traditional single-leg hop tests to provide a more ecologically valid test that incorporates the integration of physical and cognitive function for return to sport. The test–retest reliability of the 4 new neurocognitive hop tests is highly reliable and does not change systematically.
Kayla E. Boehm and Kevin C. Miller
Clinical Scenario: Exertional heat stroke (EHS) is a medical emergency characterized by body core temperatures >40.5°C and central nervous system dysfunction. An EHS diagnosis should be immediately followed by cold-water immersion (CWI). Ideally, EHS victims cool at a rate >0.15°C/min until their temperature reaches 38.9°C. While generally accepted, these EHS treatment recommendations often stem from research that examined only males. Since gender differences exist in anthropomorphics (eg, body surface area, lean body mass) and anthropomorphics impact CWI cooling rates, it is possible that CWI cooling rates may differ between genders. Clinical Question: Do CWI rectal temperature (T rec) cooling rates differ between hyperthermic males and females? Summary of Findings: The average T rec cooling rate across all examined studies for males and females was 0.18 (0.05) and 0.24 (0.03)°C/min, respectively. Hyperthermic females cooled ∼33% faster than males. Clinical Bottom Line: Hyperthermic females cooled faster than males, most likely because of higher body surface area to mass ratios and less lean body mass. Regardless of gender, CWI is highly effective at lowering T rec. Clinicians must be able to treat all EHS victims, regardless of gender, with CWI, given its high survival rate when implemented appropriately. Strength of Recommendation: Moderate evidence (2 level 3 studies) suggests that females cool faster than males when treated with CWI following severe hyperthermia. Despite gender differences, cooling rates exceeded cooling rate recommendations for EHS victims (ie, 0.15°C/min).
Timothy M. Wohlfert and Kevin C. Miller
Clinical Scenario: Exertional heat stroke (EHS) is a potentially deadly heat illness and poses a significant health risk to athletes; EHS survival rates are near 100% if properly recognized and treated. Whole-body cold water immersion (CWI) is the most effective method for lowering body core temperature. Precooling (PC) with CWI before exercise may prevent severe hyperthermia or EHS by increasing the body’s overall heat storage capacity. However, PC may also alter athletes’ perception of how hot they feel or how hard they are exercising. Consequently, they may be unable to accurately perceive their body core temperature or how hard they are working, which may predispose them to severe hyperthermia or EHS. Clinical Question: Does PC with whole-body CWI affect thermal sensation (TS) or rating of perceived exertion (RPE) during exercise in the heat? Summary of Key Findings: In 4 studies, RPE during exercise ranged from 12 (2.0) to 20 (3.0), with no clinically meaningful differences between PC and control trials. TS scores ranged from 2 (1.0) to 8 (0.5) in control trials and from 2 (1.0) to 7.5 (0.5) during PC trials. Clinical Bottom Line: PC did not cause clinically meaningful differences in RPE or TS during exercise. It is unlikely that PC would predispose athletes to EHS by altering perceptions of exercise intensity or body core temperature. Strength of Recommendation: None of the reviewed studies (all level-2 studies with Physiotherapy Evidence Database scores ≥ 5) suggest that PC with CWI influences RPE or TS in exercising males.
Samantha L. Winter, Sarah M. Forrest, Joanne Wallace and John H. Challis
The purpose of this study was to validate a new geometric solids model, developed to address the lack of female-specific models for body segment inertial parameter estimation. A second aim was to determine the effect of reducing the number of geometric solids used to model the limb segments on model accuracy. The full model comprised 56 geometric solids, the reduced model comprised 31, and the basic model comprised 16. Predicted whole-body inertial parameters were compared with direct measurements (reaction board, scales), and predicted segmental parameters with those estimated from whole-body dual x-ray absorptiometry scans for 28 females. The percentage root mean square error (%RMSE) for whole-body volume was <2.5% for all models and 1.9% for the full model. The %RMSE for whole-body center of mass location was <3.2% for all models. The %RMSE whole-body mass was <3.3% for the full model. The RMSE for segment masses was <0.5 kg (<0.5%) for all segments; Bland-Altman analysis showed the full and reduced models could adequately model thigh, forearm, foot, and hand segments, but the full model was required for the trunk segment. The proposed model was able to accurately predict body segment inertial parameters for females; more geometric solids are required to more accurately model the trunk.
Stephan R. Fisher, Justin H. Rigby, Joni A. Mettler and Kevin W. McCurdy
Clinical Scenario: Cryotherapy is one of the most commonly used modalities for postexercise muscle recovery despite inconsistencies in the literature validating its effectiveness. With the need to find a more effective modality, photobiomodulation therapy (PBMT) has gained popularity because of recent research demonstrating its ability to accelerate the muscle recovery process. Focused Clinical Question: Is PBMT more effective than cryotherapy at reducing recovery time and decreasing delayed onset muscle soreness after strenuous exercise? Summary of Key Findings: Three moderate- to high-quality double-blinded, randomized, placebo-controlled trials and 2 low- to moderate-quality translational studies performed on rats were included in this critically appraised topic. All 5 studies supported the use of PBMT over cryotherapy as a treatment for postexercise muscle recovery following exercise. PBMT was superior in reducing creatine kinase, inflammation markers, and blood lactate compared with cryotherapy, following strenuous/high intensity aerobic or strength muscular exercise. PBMT was also shown to improve postexercise muscle performance and function more than cryotherapy. Clinical Bottom Line: There is moderate evidence to suggest the use of PBMT over cryotherapy postexercise to enhance muscle recovery in trained and untrained athletes. Shorter recovery times and increased muscle performance can be seen 24 to 96 hours following PBMT application. Strength of Recommendation: Based on consistent findings from all 5 studies, there is grade B evidence to support the use of PBMT over cryotherapy for more effective postexercise recovery of skeletal muscle performance.