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).
Kayla E. Boehm and Kevin C. Miller
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.
Context: Periodic assessment of knee extensor muscle strength and size is important for all ages to evaluate the functional status of individuals and to identify and treat those at risk for mobility problems and frailty; however, it is not fully understood whether these field-based simplified approaches correspond to evaluation in knee extensor muscle strength or size. Objective: To examine the relationship between field-based simplified evaluation approaches and knee extensor muscle strength or size in young women. Design: Experimental. Setting: University research laboratory. Subjects: A total of 62 university freshmen women volunteered to participate in this study. Main Outcome Measures: Knee extensor muscle thickness was measured at the anterior half of thigh length; muscle strength was measured when subjects performed knee extension. Field-based simplified approaches (sit-to-stand, standing long jump, handgrip, and upper leg 50% [thigh] girth) were also measured. Results: Maximal strength was correlated with thigh girth, handgrip, and standing long jump, but not with the sit-to-stand test. Muscle thickness was correlated with thigh girth and handgrip, but not with standing long jump or the sit-to-stand test. A stepwise multiple-regression analysis was calculated using the predictor thigh girth and standing long jump to predict knee extensor maximal strength (R 2 = .295). To predict knee extensor muscle thickness, the predictor thigh girth was calculated (R 2 = .202). Conclusions: Knee extensor muscle strength and size could be evaluated by the field-based simplified approaches, in particular by the thigh girth measurement, which may be a major determinant to maintain activities of daily living for healthy young women. However, the 4 field-based simplified approaches appear to be still not of high impact.
Jennifer M. Medina McKeon and Patrick O. McKeon
John D. McCamley, Eric L. Cutler, Kendra K. Schmid, Shane R. Wurdeman, Jason M. Johanning, Iraklis I. Pipinos and Sara A. Myers
Patients with peripheral artery disease (PAD) experience significant leg dysfunction. The effects of PAD on gait include shortened steps, slower walking velocity, and altered gait kinematics and kinetics, which may confound joint torques and power measurements. Spatiotemporal parameters and joint torques and powers were calculated and compared between 20 patients with PAD and 20 healthy controls using independent t tests. Separate analysis of covariance models were used to evaluate group differences after independently adjusting for gait velocity, stride length, and step width. Compared with healthy controls, patients with PAD exhibited reduced peak extensor and flexor torques at the knee and hip. After adjusting for all covariates combined, differences between groups remained for ankle power generation in late stance and knee flexor torque. Reduced walking velocity observed in subjects affected by PAD was closely connected with reductions in joint torques and powers during gait. Gait differences remained at the knee and ankle after adjusting for the combined effect of spatiotemporal parameters. Improving muscle function through exercise or with the use of assistive devices needs to be a key tool in the development of interventions that aim to enhance the ability of PAD patients to restore spatiotemporal gait parameters.
Genki Hatano, Shigeyuki Suzuki, Shingo Matsuo, Satoshi Kataura, Kazuaki Yokoi, Taizan Fukaya, Mitsuhiro Fujiwara, Yuji Asai and Masahiro Iwata
Context: Hamstring injuries are common, and lack of hamstring flexibility may predispose to injury. Static stretching not only increases range of motion (ROM) but also results in reduced muscle strength after stretching. The effects of stretching on the hamstring muscles and the duration of these effects remain unclear. Objective: To determine the effects of static stretching on the hamstrings and the duration of these effects. Design: Randomized crossover study. Setting: University laboratory. Participants: A total of 24 healthy volunteers. Interventions: The torque–angle relationship (ROM, passive torque [PT] at the onset of pain, and passive stiffness) and isometric muscle force using an isokinetic dynamometer were measured. After a 60-minute rest, the ROM of the dynamometer was set at the maximum tolerable intensity; this position was maintained for 300 seconds, while static PT was measured continuously. The torque–angle relationship and isometric muscle force after rest periods of 10, 20, and 30 minutes were remeasured. Main Outcome Measures: Change in static PT during stretching and changes in ROM, PT at the onset of pain, passive stiffness, and isometric muscle force before stretching were compared with 10, 20, and 30 minutes after stretching. Results: Static PT decreased significantly during stretching. Passive stiffness decreased significantly 10 and 20 minutes after stretching, but there was no significant prestretching versus poststretching difference after 30 minutes. PT at the onset of pain and ROM increased significantly after stretching at all rest intervals, while isometric muscle force decreased significantly after all rest intervals. Conclusions: The effect of static stretching on passive stiffness of the hamstrings was not maintained as long as the changes in ROM, stretch tolerance, and isometric muscle force. Therefore, frequent stretching is necessary to improve the viscoelasticity of the muscle–tendon unit. Muscle force decreased for 30 minutes after stretching; this should be considered prior to activities requiring maximal muscle strength.
Anna Lina Rahlf, Klaus-Michael Braumann and Astrid Zech
Context: Although increasingly used for therapeutic treatment, only limited evidence exists regarding the effects of kinesio taping on patients with knee osteoarthritis (OA). Objective: To determine the effects of kinesio taping on pain, function, gait, and neuromuscular control concerning patients with knee OA. Design: Randomized sham-controlled trial. Setting: University laboratory. Participants: A total of 141 patients (65.1 [7.0] y) with a clinical and radiographic diagnosis of knee OA. Intervention: Kinesio tape, sham tape, or no tape for 3 consecutive days. Main Outcome Measures: Self-reported pain, stiffness, and function were measured by the Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC). Further tests included the Balance Error Scoring System, 10-m walk test, the maximum voluntary isometric contraction force of the quadriceps femoris, and knee active range of motion. Results: At baseline, there were no differences in all outcomes between groups except for knee flexion. Significant effects were found for WOMAC pain (tape vs sham, P = .05; tape vs control, P = .047), stiffness (tape vs sham, P = .01; tape vs control, P ≤ .001), and physical function (tape vs sham, P = .03; tape vs control P = .004). No interactions were found for balance, muscle strength, walking speed, or active range of motion. Conclusion: Wearing kinesio tape for 3 consecutive days had beneficial effects regarding self-reported clinical outcomes of pain, joint stiffness, and function. This emphasizes that kinesio taping might be an adequate conservative treatment for the symptoms of knee OA.