Neuromuscular electrical stimulation attenuates thigh skeletal muscles atrophy but not trunk muscles after spinal cord injury

The current study examined the effects of 12 weeks of surface neuromuscular electrical stimulation (NMES) and ankle weights on the cross-sectional areas (CSAs) of three thigh [Gracilis (Gra), Sartorious (Sar) and Adductor (Add)] as well as two trunk [hip flexor (HF) and back extensor (BE)] muscle groups in men with spinal cord injury (SCI). Seven individuals with chronic motor complete SCI were randomly assigned into a resistance training + diet (RT + diet; n = 4) or diet control (n = 3) groups. The RT + diet group underwent twice weekly training with surface NMES and ankle weights for 12 weeks. Training composed of four sets of 10 repetitions of leg extension exercise while sitting in their wheelchairs. Both groups were asked to monitor their dietary intake. Magnetic resonance images were captured before and after 12 weeks of interventions. Gra muscle CSA showed no change before and after interventions. A significant interaction (P = 0.001) was noted between both groups as result of 9% increase and 10% decrease in the Gra muscle CSA of the RT + diet and diet groups, respectively. Sar muscle CSA increased [1.7 ± 0.4–2.5 ± 0.5 cm²; P = 0.029] in the RT + diet group with no change [2.9 ± 1.4–2.6 ± 1.3 cm²] in the diet group; with interaction noted between both groups (P = 0.002). Analysis of covariance indicated that Add muscle CSA was 38% greater in the RT + diet compared to the diet group (P = 0.025) after 12 weeks; a trend of interaction was also noted between both groups (P = 0.06). HF and BE muscle groups showed no apparent changes in CSA in both groups. The results suggested that surface NMES can delay the process of progressive skeletal muscle atrophy after chronic SCI. However, the effects are localized to the trained thigh muscles and do not extend to the proximal trunk muscles.     

Distal skeletal tibia assessed by HR-pQCT is highly correlated with femoral and lumbar vertebra failure loads

Dual energy X-ray absorptiometry (DXA) is the standard for assessing fragility fracture risk using areal bone mineral density (aBMD), but only explains 60–70% of the variation in bone strength. High-resolution peripheral quantitative computed tomography (HR-pQCT) provides 3D-measures of bone microarchitecture and volumetric bone mineral density (vBMD), but only at the wrist and ankle. Finite element (FE) models can estimate bone strength with 86–95% precision. The purpose of this study is to determine how well vBMD and FE bone strength at the wrist and ankle relate to fracture strength at the hip and spine, and to compare these relationships with DXA measured directly at those axial sites. Cadaveric samples (radius, tibia, femur and L4 vertebra) were compared within the same body. The radius and tibia specimens were assessed using HR-pQCT to determine vBMD and FE failure load. aBMD from DXA was measured at the femur and L4 vertebra. The femur and L4 vertebra specimens were biomechanically tested to determine failure load. aBMD measures of the axial skeletal sites strongly correlated with the biomechanical strength for the L4 vertebra (r = 0.77) and proximal femur (r = 0.89). The radius correlated significantly with biomechanical strength of the L4 vertebra for vBMD (r = 0.85) and FE-derived strength (r = 0.72), but not with femur strength. vBMD at the tibia correlated significantly with femoral biomechanical strength (r = 0.74) and FE-estimated strength (r = 0.83), and vertebral biomechanical strength for vBMD (r = 0.97) and FE-estimated strength (r = 0.91). The higher correlations at the tibia compared to radius are likely due to the tibia’s weight-bearing function.     

The Quételet index revisited in children and adults

BackgroundThe body mass index (BMI) is based on the original concept that body weight increases as a function of height squared. As an indicator of obesity the modern BMI assumption postulates that adiposity also increases as a function of height in states of positive energy balance.ObjectiveTo evaluate the BMI concept across different adiposity magnitudes, in both children and adults.MethodsWe studied 975 individuals who underwent anthropometric evaluation: 474 children and 501 adults. Tetrapolar bioimpedance analysis was used to assess body fat and lean mass.ResultsBMI significantly correlated with percentage of body fat (%BF; children: r = 0.893; adults: r = 0.878) and with total fat mass (children: r = 0.967; adults: r = 0.953). In children, body weight, fat mass, %BF and waist circumference progressively increased as a function of height squared. In adults body weight increased as a function of height squared, but %BF actually decreased with increasing height both in men (r = −0.406; p < 0.001) and women (r = −0.413; p < 0.001). Most of the BMI variance in adults was explained by a positive correlation of total lean mass with height squared (r² = 0.709), and by a negative correlation of BMI with total fat mass (r = −0.193).ConclusionsBody weight increases as a function of height squared. However, adiposity progressively increases as a function of height only in children. BMI is not an ideal indicator of obesity in adults since it is significantly influenced by the lean mass, even in obese individuals.     

Kinematic chain reactions on trunk and dynamic postural steadiness in subjects with recurrent low back pain

Although subjects with recurrent low back pain (LBP) demonstrate altered trunk control, the kinematic and kinetic responses of the trunk have not been carefully investigated. This study was conducted to compare the standing time, spine range of motion (ROM), and dynamic postural steadiness index (DPSI) based on visual condition between subjects with and without recurrent LBP during upright one leg standing. Sixty-three individuals participated in the study, including 34 control subjects and 29 subjects with recurrent LBP. The DPSI was a composite of the medio-lateral (MLSI), anterior-posterior (APSI), and vertical steadiness indices (VSI) on a force platform. The control group demonstrated longer standing time (s) during the eyes-open condition than the LBP group (26.82 ± 6.03 vs. 19.87 ± 9.36; t = 2.96, p = 0.01). Regarding spine ROM, visual condition was significantly different between groups (F = 7.09, p = 0.01) and demonstrated interactions with spine region and group (F = 5.53, p = 0.02). For the kinetic measures, there was a significant interaction between visual conditions and indices (F = 25.30, p = 0.001). In the LBP group, the DPSI was significantly correlated with the MLSI (r = 0.59, p = 0.002), APSI (r = 0.44, p = 0.03), and VSI (r = 0.98, p = 0.01) in the eyes-closed condition. Overall, the results of this study indicated that the LBP group decreased thorax and lumbar spine rotations during the eyes-closed condition. The LBP group also demonstrated positive correlations with the kinetic indices, enhancing dynamic postural steadiness in the eyes-closed condition in order to possibly avoid pain or further injury. This dynamic postural steadiness strategy is necessary to improve kinetic and kinematic chain reactions in the LBP group. This compensatory pattern supports the development of optimal postural correction strategies to prevent LBP recurrence and might represent a chain reaction to protect trunk control without visual input.     

How symmetric are metal-on-metal hip resurfacing patients during gait? Insights for the rehabilitation

Metal-on-metal hip resurfacing patients demonstrate hip biomechanics closer to normal in comparison to total hip arthroplasty during gait. However, it is not clear how symmetric is the gait of hip resurfacing patients. Biomechanical data of 12 unilateral metal-on-metal hip resurfacing participants were collected during gait at a mean time of 45 months (SD 24) after surgery. Ankle, knee, hip, pelvis and trunk kinematics and kinetics of both sides were measured with a motion and force-capture system. Principal component analysis and mean hypothesis’ tests were used to compare the operated and healthy sides. The operated side had prolonged ankle eversion angle during late stance and delayed increased ankle inversion angle during early swing (p = 0.008; effect size = 0.70), increased ankle inversion moment during late stance (p = 0.001; effect size = 0.78), increased knee adduction angle during swing (p = 0.044; effect size = 0.57), decreased knee abduction moment during stance (p = 0.05; effect size = 0.40), decreased hip range of motion in the sagittal plane (p = 0.046; effect size = 0.56), decreased range of hip abduction moment during stance (p = 0.02; effect size = 0.63), increased hip range of motion in the transverse plane (p = 0.02; effect size = 0.62), decreased hip internal rotation moment during the transition from loading response to midstance (p = 0.001; effect size = 0.81) and increased trunk ipsilateral lean (p = 0.03; effect size = 0.60). Therefore, hip resurfacing patients have some degree of asymmetry in long term, which may be related to hip weakness and decreased range of motion, to foot misalignments and to strategies implemented to reduce loading on the operated hip. Interventions such as muscle strengthening and stretching, insoles and gait feedback training may help improving symmetry following hip resurfacing.     

Standardized activities of daily living in presence of sub-acute low-back pain: A pilot study

The aim of this pilot study was to investigate how sub-acute low-back pain (LBP) patients differed with respect to control in movements and muscle activation during standardized tasks representing daily living activities, and explore relationships between cognition and measured motor performance. Linear and nonlinear parameters were computed from kinetics, kinematics and muscle activity recorded for 12 sub-acute patients and 12 healthy matched controls during trunk flexion, sit-to-stand from a chair and lifting a box. Cognitive variables were collected to explore relationships with biomechanical parameters. For trunk flexion, left external abdominal oblique muscle activity level was lower for patients compared with controls (p < 0.05), whereas sample entropy (complexity) was higher (p < 0.05). Normalized mutual information was lower for patients compared with controls for left and right erector spinae (p < 0.05). Level of activity of left external abdominal oblique correlated negatively with cognitive ignoring and positively with catastrophizing (p ? 0.05), and catastrophizing also correlated positively with functional connectivity of abdominal muscles (p < 0.05). Signs of reorganization in muscle activation pointed towards different synergistic actions in trunk muscles in sub-acute LBP patients compared with controls. The interplay with maladaptive cognition suggested that in the subacute stage of LBP, both biomechanical and cognitive factors should be taken into account.     

Kinematic analyses of trunk stability in one leg standing for individuals with recurrent low back pain

This prospective study examined normalized stability differences based on dominance side and visual feedback. Subjects with low back pain (LBP) (n = 26; 9 men, 17 women) and without LBP (n = 28; 11 men, 17 women) participated in this study. All subjects were asked to maintain single leg standing balance with the contralateral hip flexed 90° for 25 s. The outcome measures included normalized holding duration and stability. The combined rotation (R_xyz) was also calculated to compare the upper and lower thorax and lumbar axes relative to the core spine axis. The holding duration was significantly different between groups (T = ?2.21, p = 0.03). The subjects without recurrent LBP (control group) demonstrated longer hold duration times (24.60 ± 4.2 s) than the subjects with recurrent LBP (21.2 ± 7.1 s). For the normalized hold duration, there was a significant difference between groups based on visual input (F = 7.13, p = 0.009). There was also a significant difference in standing stability based on visual input (F = 93.93, p = 0.0001) and trunk area (F = 101.51, p = 0.0001). In addition, the normalized stability was significantly different based on dominance and visual input (F = 11.28, p = 0.002). Therefore, trunk stability could prompt an uncoordinated bracing effect with poor proprioception from injury to passive structures or due to interference of pain during central processing of information in subjects with recurrent LBP.     

How do rocker-soled shoes influence the knee adduction moment in people with knee osteoarthritis? An analysis of biomechanical mechanisms

The primary objective was to examine mechanisms behind previously observed changes in the knee adduction moment (KAM) with rocker-soled shoes, in participants sub-grouped according to whether they experienced an immediate decrease, or increase, in peak KAM. In subgroups where frontal plane knee ground reaction force (GRF) lever-arm emerged as a significant predictor, a secondary aim was to examine biomechanical factors that contributed to change in this parameter. Thirty individuals with symptomatic, radiographic knee osteoarthritis (OA) underwent 3D gait analysis in unstable rocker-soled shoes and non-rocker-soled shoes. Multiple regression analyses, within each subgroup, examined relationships between changes in frontal plane knee-GRF lever arm and frontal plane resultant GRF magnitude and changes in peak KAM and KAM impulse between shoe conditions. In the subgroup that decreased peak KAM with rocker-soled shoes (n = 23), change in knee-GRF lever arm and frontal plane GRF magnitude at peak KAM together were significant predictors of change in peak KAM; however, only change in mean knee-GRF lever arm significantly predicted change in KAM impulse. Decreased medial GRF magnitude, increased lateral trunk lean towards the stance limb and reduced varus/increased valgus hip-knee-ankle angle were associated with a lower knee-GRF lever arm in this group, with rocker-soled shoes. In contrast, none of the independent variables predicted changes in KAM in the subgroup who increased peak KAM with rocker-soled shoes (n = 7).     

Electromyographic patterns of lower limb muscles during apprehensive gait in younger and older female adults

ObjectiveInvestigate the influence of apprehensive gait on activation and cocontraction of lower limb muscles of younger and older female adults.MethodsData of 17 younger (21.47 ± 2.06 yr) and 18 older women (65.33 ± 3.14 yr) were considered for this study. Participants walked on the treadmill at two different conditions: normal gait and apprehensive gait. The surface electromyographic signals (EMG) were recorded during both conditions on: rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), tibialis anterior (TA), gastrocnemius lateralis (GL), and soleus (SO).ResultsApprehensive gait promoted greater activation of thigh muscles than normal gait (F = 5.34 and p = 0.007, for significant main effect of condition; RF, p = 0.002; VM, p < 0.001; VL, p = 0.003; and BF, p = 0.001). Older adults had greater cocontraction of knee and ankle stabilizer muscles than younger women (F = 4.05 and p = 0.019, for significant main effect of groups; VM/BF, p = 0.010; TA/GL, p = 0.007; and TA/SO, p = 0.002).ConclusionApprehensive gait promoted greater activation of thigh muscles and older adults had greater cocontraction of knee and ankle stabilizer muscles. Thus, apprehensive gait may leads to increased percentage of neuromuscular capacity, which is associated with greater cocontraction and contribute to the onset of fatigue and increased risk of falling in older people.     

Decreased lower limb muscle recruitment contributes to the inability of older adults to recover with a single step following a forward loss of balance

In response to a balance disturbance, older individuals often require multiple steps to prevent a fall. Reliance on multiple steps to recover balance is predictive of a future fall, so studies should determine the mechanisms underlying differences between older adults who can and cannot recover balance with a single step. This study compared neural activation parameters of the major leg muscles during balance recovery from a sudden forward loss of balance in older individuals capable of recovering with a single step and those who required multiple steps to regain balance. Eighty-one healthy, community dwelling adults aged 70 ± 3 participated. Loss of balance was induced by releasing participants from a static forward lean. Participants performed four trials at three initial lean magnitudes and were subsequently classified as single or multiple steppers. Although step length was shorter in multiple compared to single steppers (F = 9.64; p = 0.02), no significant differences were found between groups in EMG onset time in the step limb muscles (F = 0.033–0.769; p = 0.478–0.967). However, peak EMG normalised to values obtained during maximal voluntary contraction was significantly higher in single steppers in 6 of the 7 stepping limb muscles (F = 1.054–4.167; p = 0.045–0.024). These data suggest that compared to multiple steppers, single steppers recruit a larger proportion of the available motor unit pool during balance recovery. Thus, modulation of EMG amplitude plays a larger role in balance recovery than EMG timing in this context.     

Do adipokines underlie the association between known risk factors and breast cancer among a cohort of United States women?

Introduction: Obesity is a well-established risk factor for postmenopausal breast cancer, but mechanisms underlying the association are unclear. Adipocyte-derived, cytokine-like adipokines have been suggested as contributory factors. To evaluate their association with breast cancer risk factors and breast cancer risk, we conducted a nested case-control study of 234 postmenopausal breast cancer cases and 234 controls in a cohort of U.S. women with prospectively-collected serum samples obtained in the mid 1970s and followed for up to 25 years. Methods: Adiponectin, absolute plasminogen activator inhibitor-1 (aPAI-1), and resistin were measured by a multiplex immunoassay. Sex hormones were available for 67 cases and 67 controls. Results: Among controls, we found that lower levels of adiponectin and higher levels of aPAI-1 were correlated with increasing levels of estradiol (Spearman r = ?0.26, p-value = 0.033; r = 0.42, p = 0.0003), decreasing levels of sex hormone binding globulin (r = 0.38, p = 0.0013; r = ?0.32, p = 0.0076), and increasing body mass index (BMI) (r = ?0.31, p =  < 0.0001; r = 0.39, p =  < 0.0001). Hormones were not associated with resistin. Among the relatively small percentage of women using postmenopausal hormones at the time of blood collection (13.7%), aPAI-1 levels were higher than in non-users (p = 0.0054). Breast cancer risk was not associated with circulating levels of adiponectin (age-adjusted p for linear trend = 0.43), aPAI-1 (p = 0.78), or resistin (p = 0.91). The association was not confounded by BMI, parity, age at first full-term birth, age at menopause, current postmenopausal hormone use, and circulating sex steroid hormones. Furthermore, adipokine associations were not modified by BMI (p > 0.05). The lack of association with risk may be due to measurement error of the laboratory assays. Discussion: lower levels of adiponectin and higher levels of aPAI-1 measured in prospectively-collected serum from postmenopausal women were associated with increasing BMI but not breast cancer risk.     

Association of urinary 15-F2t-isoprostane level with oxygen desaturation and carotid intima–media thickness in nonobese sleep apnea patients

Obstructive sleep apnea (OSA) is characterized by recurrent apnea during sleep that may unbalance oxidative stress, increasing atherosclerosis. Among oxidative stress markers, 15-F_2t-isoprostane is considered one of the most sensitive and specific metabolites of lipid peroxidation. To explore the relationship between urinary 15-F_2t-isoprostane with sleep apnea severity and carotid modifications in nonobese OSA patients, 31 nonobese sleep apnea patients were studied, along with 10 lean subjects without OSA. Patients were assessed by polysomnography, blood pressure measurement, and ultrasonography to determine the carotid intima–media thickness (IMT). Urinary 15-F_2t-isoprostanes were measured by liquid chromatography–tandem mass spectrometry. Urinary 15-F_2t-isoprostane concentrations were increased in severe OSA patients compared to control subjects (20.2 ± 7.3 vs 12.3 ± 2.8 ng/mmol creatinine; P = 0.020). Mean carotid IMT was correlated with 15-F_2t-isoprostane (r = 0.532; P < 0.001) and with the apnea–hypopnea index (r = 0.345; P = 0.029). 15-F_2t-Isoprostane level was related to the night time spent at SaO₂ < 90% (r = 0.478; P = 0.002), the apnea–hypopnea index (r = 0.465; P = 0.003), and the mean nocturnal SaO₂ (r = ? 0.424; P = 0.007). These results showed a relationship between lipid peroxidation, carotid intima–media thickness, and intermittent hypoxia in nonobese OSA patients, thus reinforcing the hypothesis that oxidative stress could be involved in the early atherosclerotic process.     

Efecto de los movimientos explosivos y de impacto aplicados en piscina sobre la composición corporal,la fuerza y la densidad mineral ósea de mujeres mayores de 60 años

BackgroundOsteoporosis is characterised by loss of bone mass and deterioration of bone tissue microarchitecture that leads to fragility related to the risk of fractures. The aim of the study is to analyse the effects of a training program based on explosive movements and impact, assessed in a swimming pool, on body composition, explosive strength and bone mineral density in women over 60 years old.Material and methodsA total of 35 healthy physically active women (60 ± 4.19 years) were divided into a training pool group using multi jumps (JG) and a control group (CG). JG trained for 24 weeks, 3 times a week, an hour and a half per session. Body composition testing, explosive strength, and bone mineral density were assessed before and after the program.ResultsThere were differences in the explosive force (JG vs CG = P < .05 to .001) and the estimated power (JG vs CG = P < .05 to .002) between JG vs CG, with significant increases in JG. There were no significant differences in the percentage of fat and lean mass, bone mineral density lumbar and femoral between groups, although slightly significant increases in bone mineral density lumbar and femoral could be seen in JG after program implementation (JG pre-test vs JG post- test = P < .05).ConclusionsThe training program with impact and explosive movements assessed in a pool induces gains in muscle strength and power with slight adaptations in body mass index in women over 60 years.     

Anthropometric features and cutaneous melanoma risk: A prospective cohort study in French women

BackgroundEpidemiological studies on anthropometric features and cutaneous melanoma risk in women yielded inconsistent results, with few analyses involving prospective cohort data. Our objective was to explore several anthropometric characteristics in relation to the risk of melanoma in women.MethodsWe prospectively analysed data from E3N, a French cohort involving 98,995 women born in 1925–1950. Participants completed self-administered questionnaires sent biennially over 1990–2008. Relative risks (RRs) and 95% confidence intervals (CIs) were computed using Cox proportional hazards regression models, adjusted for age, number of naevi, freckling, skin and hair colour, skin sensitivity to sun exposure, residential sun exposure, and physical activity.ResultsHeight was positively associated with melanoma in age-adjusted models only (RR = 1.27, 95% CI = 1.05–1.55 for ≥164 cm vs. <160 cm; P for trend = 0.02). After full adjustment, there was a significantly positive relationship between sitting-to-standing height ratio and melanoma risk (RR = 1.40, 95% CI = 1.06–1.86 for ≥0.533 vs. <0.518; P for trend = 0.02). A large body shape at menarche was inversely associated with the risk of melanoma (RR = 0.78, 95% CI = 0.62–0.98; compared with lean). However, weight, body mass index, body surface area, waist or hip circumference, sitting height or leg length were not significantly associated with risk.ConclusionThese results suggest that height, sitting-to-standing height ratio and body shape at menarche may be associated with melanoma risk. Further research is required to confirm these relationships and better understand the underlying mechanisms.     

Descriptive analysis of kinematics and kinetics of catchers throwing to second base from their knees

In order to decrease the amount of time that it takes the catcher to throw the ball, a catcher may chose to throw from the knees. Upper extremity kinematics may play a significant role in the kinetics about the elbow observed in catchers throwing from the knees. If relationships between kinematics and kinetics exist then the development of training and coaching instruction may help in reduced upper extremity injury risk. Twenty-two baseball and softball catchers (14.36 ± 3.86 years; 165.11 ± 17.54 cm; 65.67 ± 20.60 kg) volunteered. The catchers exhibited a less trunk rotation (5.6 ± 16.2°), greater elbow flexion (87.9 ± 21.4°) and decreased humeral elevation (71.1 ± 12.3°) at the event of maximum shoulder external rotation as compared to what has previously reported in catchers. These variables are important, as they have previously been established as potential injury risk factors in pitchers, however it is not yet clear the role these variables play in catchers’ risk of injury. A positive relationship between elbow varus torque during the deceleration phase and elbow flexion at MIR was observed (r = 0.609; p = 0.003). Throwing from the knees reduces a catcher’s ability to utilize the proximal kinetic chain and this may help to explain why their kinematics and kinetics differ from what has previously been presented in the literature.     

Braking characteristics during cutting and pivoting in female soccer players

Most biomechanical studies into changing direction focus on final contact (FC), whilst limited research has examined penultimate contact (PEN). The aim of this study was to explore the kinematic and kinetic differences between PEN and FC of cutting and pivoting in 22 female soccer players (mean ± SD; age: 21 ± 3.1 years, height: 1.68 ± 0.07 m, mass: 58.9 ± 7.3 kg). Furthermore, the study investigated whether horizontal force–time characteristics during PEN were related to peak knee abduction moments during FC. Three dimensional motion analyses of cutting and pivoting on the right leg were performed using Qualysis ‘Proreflex’ infrared cameras (240 Hz). Ground reaction forces (GRF) were collected from two AMTI force platforms (1200 Hz) to examine PEN and FC. Both manoeuvres involved significantly (P < 0.05) greater knee joint flexion angles, peak horizontal GRF, but lower average horizontal GRF during PEN compared to FC. Average horizontal GRF during PEN (R = −0.569, R² = 32%, P = 0.006) and average horizontal GRF ratio (R = 0.466, R² = 22%, P = 0.029) were significantly related to peak knee abduction moments during the FC of cutting and pivoting, respectively. The results indicate PEN during pre-planned changing direction helps reduce loading on the turning leg where there is greater risk of injuries to knee ligaments.     

Punto de corte de espesor de tejido adiposo epicárdico para predecir síndrome metabólico en población venezolana

ObjectiveTo define an echocardiographically-assessed cut-off point for epicardial adipose tissue (EAT) thickness associated to metabolic syndrome (MS) components in Venezuelan subjects.MethodsFifty-two subjects aged 20-65 years diagnosed with MS according to International Diabetes Federation criteria and 45 sex- and age-matched controls were selected. Blood glucose and plasma lipids were tested; EAT thickness and left ventricular mass were measured by echocardiography.ResultsNo significant age and sex differences were found between the two groups. Body weight, body mass index, waist circumference, and systolic and diastolic blood pressure were significantly higher (P = .0001) in the MS group. This group showed significantly higher levels of fasting blood glucose (P = .0001), total cholesterol (P = .002), LDL-C (P = .007), non-HDL-C (P = .0001), triglycerides (P = .0001), Tg-HDL-C ratio (P = .0001), and lower HDL-C levels (P = .0001) as compared to the control group. EAT thickness (P = .0001) and left ventricular mass (P = .017) were significantly higher in the MS group. The ROC curve showed an AUC of 0.852 (P = .0001) with a power of the test of 0.99. A 5-mm EAT thickness showed a sensitivity of 84.62% (95% CI: 71.9-93.1) and a specificity of 71.11% (95% CI: 55.7-83.6) for predicting MS. The odds ratio of this population for experiencing MS due to an EAT ≥ 5 mm was 8.25 (95% CI: 3.15-21.56; P = .0001).ConclusionAn EAT value ≥ 5 mm has good sensitivity and specificity for predicting MS in the Venezuelan population.     

Knee flexor strength and bicep femoris electromyographical activity is lower in previously strained hamstrings

The aim of this study was to determine if athletes with a history of hamstring strain injury display lower levels of surface EMG (sEMG) activity and median power frequency in the previously injured hamstring muscle during maximal voluntary contractions. Recreational athletes were recruited, 13 with a history of unilateral hamstring strain injury and 15 without prior injury. All athletes undertook isokinetic dynamometry testing of the knee flexors and sEMG assessment of the biceps femoris long head (BF) and medial hamstrings (MHs) during concentric and eccentric contractions at ±180 and ±60° s^?1. The knee flexors on the previously injured limb were weaker at all contraction speeds compared to the uninjured limb (+180° s^?1 p = 0.0036; +60° s^?1 p = 0.0013; ?60° s^?1 p = 0.0007; ?180° s^?1 p = 0.0007) whilst sEMG activity was only lower in the BF during eccentric contractions (?60° s^?1 p = 0.0025; ?180° s^?1 p = 0.0003). There were no between limb differences in MH sEMG activity or median power frequency from either BF or MH in the injured group. The uninjured group showed no between limb differences in any of the tested variables. Secondary analysis comparing the between limb difference in the injured and the uninjured groups, confirmed that previously injured hamstrings were mostly weaker (+180° s^?1 p = 0.2208; +60° s^?1 p = 0.0379; ?60° ^?1 p = 0.0312; ?180° s^?1 p = 0.0110) and that deficits in sEMG were confined to the BF during eccentric contractions (?60° s^?1 p = 0.0542; ?180° s^?1 p = 0.0473). Previously injured hamstrings were weaker and BF sEMG activity was lower than the contralateral uninjured hamstring. This has implications for hamstring strain injury prevention and rehabilitation which should consider altered neural function following hamstring strain injury.     

Validity of trunk extensor and flexor torque measurements using isokinetic dynamometry

This study aimed to evaluate the validity and test–retest reliability of trunk muscle strength testing performed with a latest-generation isokinetic dynamometer. Eccentric, isometric, and concentric peak torque of the trunk flexor and extensor muscles was measured in 15 healthy subjects. Muscle cross sectional area (CSA) and surface electromyographic (EMG) activity were respectively correlated to peak torque and submaximal isometric torque for erector spinae and rectus abdominis muscles. Reliability of peak torque measurements was determined during test and retest sessions. Significant correlations were consistently observed between muscle CSA and peak torque for all contraction types (r = 0.74−0.85; P < 0.001) and between EMG activity and submaximal isometric torque (r ⩾ 0.99; P < 0.05), for both extensor and flexor muscles. Intraclass correlation coefficients were comprised between 0.87 and 0.95, and standard errors of measurement were lower than 9% for all contraction modes. The mean difference in peak torque between test and retest ranged from −3.7% to 3.7% with no significant mean directional bias. Overall, our findings establish the validity of torque measurements using the tested trunk module. Also considering the excellent test–retest reliability of peak torque measurements, we conclude that this latest-generation isokinetic dynamometer could be used with confidence to evaluate trunk muscle function for clinical or athletic purposes.