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Background: This study examined the impact of a 4-week school-based sprint interval training program on cardiorespiratory fitness (CRF), daily physical activity (PA) behavior, and cardiometabolic risk (CMR) outcomes in adolescents. Methods: A total of 56 adolescents (22 females) were allocated to either an intervention (n = 22; 17.0 [0.3] y) or control group (n = 30; 16.8 [0.5] y). Intervention group performed 5 to 6, 30 second "all out" running sprints, interspersed with 30-second rest intervals, 3 times per week, for 4 consecutive weeks, whereas control group performed their normal physical education lessons. CRF was estimated from the 20-m multistage fitness test and PA behavior was determined using accelerometry. Fasting blood samples were obtained to measure biochemical markers of CMR. Results: Significant group × time interactions were observed for CRF (5.03 [1.66 to 8.40]; P <.001; d = 0.95), sedentary time (136.15 [91.91 to 180.39]; P =.004; d = 1.8), moderate PA (57.20 [32.17 to 82.23]; P <.001; d = 1.5), vigorous PA (5.40 [4.22 to 6.57]; P <.001; d = 1.2), fasting insulin (0.37 [−0.48 to 1.21]; P =.01; d = 1.0), homeostasis model of assessment-insulin resistance (0.26 [0.15 to 0.42]; P <.001; d = 0.9), and clustered CMR score (0.22 [−0.05 to 0.68]; P <.001; d = 10.63). Conclusion: Findings of this study indicate that 4 weeks of school-based sprint interval training improves CRF, improves PA profiles, and maintains CMR in adolescents during the school term. [ABSTRACT FROM AUTHOR]

Background: Electromyographic systems are widely used in scientific and clinical practice. The reproducibility and reliability of these measures are crucial when conducting scientific research and collecting experimental data.Objective: To test the reliability of surface electromyography signals from both the Flexor Digitorum Superficialis (FDS) and Extensor Carpi Radialis Brevis (ECRB) muscles of both the left and right arms during an individual, static multi-planar maximum voluntary contraction handgrip task using the Myon 320 system (Myon AG, Switzerland).Methods: Eight right-handed male participants performed two maximal handgrip tests in five separate wrist positions using both hands. Muscle activity was recorded from both forearms. Reliability was measured using the Standard Error of Measurement (SEM), Coefficient of Variation (CV) and Intra-class correlation coefficients. Wrist joint position correlations within and between the FDS and ECRB muscle activities were also analysed.Results: Absolute reliability was shown across all positions for both hands with CV and SEM recorded at below 10%. The output measures indicate that the Myon 320 system (Myon AG, Switzerland) produces good to fair reliability when assessing forearm muscle activity. Correlations in the left FDS muscles were negative. Correlations between the left ECRB and left FDS muscles were variable but positive between the right ECRB and right FDS muscles.Conclusions: The data sets retrieved from all participants were reliably evaluated. Wrist position correlations within and between the FDS and ECRB muscles may have been influenced by hand dominance. The findings demonstrate that the methods and systems outlined in this study can be used reliably in future research. [ABSTRACT FROM AUTHOR]

Lower back pain is commonly associated with golfers. The study aimed: to determine whether thoracic- and lumbar-erector-spinae muscle display signs of muscular fatigue after completing a golf practice session, and to examine the effect of the completed practice session on club head speed, ball speed and absolute carry distance performance variables. Fourteen right- handed male golfers participated in the laboratory-based-study. Surface electromyography (EMG) data was collected from the lead and trail sides of the thoracic- and lumbar-erector-spinae muscle. Normalized root mean squared (RMS) EMG activation levels and performance variables for the golf swings were compared before and after the session. Fatigue was assessed using median frequency (MDF) and RMS during the maximum voluntary contraction (MVC) performed before and after the session. No significant differences were observed in RMS thoracic- and lumbar-erector-spinae muscle activation levels during the five phases of the golf swing and performance variables before and after the session (p > .05). Significant changes were displayed in MDF and RMS when comparing the MVC performed before and after the session (p < .05). Fatigue was evident in the trail side of the erector-spinae muscle after the session. [ABSTRACT FROM AUTHOR]

The purpose of this study was to compare the electromyography (EMG) patterns of the thoracic and lumbar regions of the erector spinae (ES) muscle during the golf swing whilst using four different golf clubs. Fifteen right-handed male golfers performed a total of twenty swings in random order using the driver, 4-iron, 7-iron and pitching-wedge. Surface EMG was recorded from the lead and trail sides of the thoracic and lumbar regions of the ES muscle (T8, L1 and L5 lateral to the spinous-process). Three-dimensional high-speed video analysis was used to identify the backswing, forward swing, acceleration, early and late follow-through phases of the golf swing. No significant differences in muscle-activation levels from the lead and trail sides of the thoracic and lumbar regions of the ES muscle were displayed between the driver, 4-iron, 7-iron and pitching-wedge (P > 0.05). The highest mean thoracic and lumbar ES muscle-activation levels were displayed in the forward swing (67–99% MVC) and acceleration (83–106% MVC) phases of the swing for all clubs tested. The findings from this study show that there were no significant statistical differences between the driver, 4-iron, 7-iron and pitching-wedge when examining muscle activity from the thoracic and lumbar regions of the ES muscle. [ABSTRACT FROM AUTHOR]

Testosterone is an important biological hormone, which displays a gradual decline with advancing age. Exercise training has been proposed as a first-line therapy for biochemical hypogonadism (clinically low serum testosterone). As such, the present investigation compared the incidence of biochemical hypogonadism (total testosterone <11.3 nmol·L-1) in a cohort of otherwise healthy lifelong sedentary men (SED [N=24], 63±5 years), compared with a positive control group of lifelong exercisers (LEX [N=16], 60±5 years) using electrochemiluminescent immunoassay. Fisher's exact test identified significantly more of the SED group were classified as biochemically hypogonadal than the LEX group (8/24 compared to 2/16 respectively; p<.05). These data provide preliminary evidence that exercise may protect against the development of low testosterone defined hypogonadism in aging men. [ABSTRACT FROM AUTHOR]

Objectives To evaluate the ability of BMI, WC, and WHtR to identify increased cardiometabolic risk in pre-adolescents. Methods This is a cross-sectional study involving 192 children (10.92 ± 0.58 years, 56% female) from the United Kingdom between 2010 and 2013. Receiver operating characteristic curves determined the discriminatory ability of BMI, WC and WHtR to identify individuals with increased cardiometabolic risk (increased clustered triglycerides, HDL-cholesterol, systolic blood pressure, cardiorespiratory fitness, and glucose). Results A WHtR ≥ 0.5 increased the odds by 5.2 (95% confidence interval 2.6 - 10.3) of having increased cardiometabolic risk. Similar associations were observed for BMI and WC. Both BMI-z and WHtR were fair predictors of increased cardiometabolic risk, although BMI-z demonstrated the best trade-off between sensitivity and specificity, 76.1% and 63.6%, compared with 68.1% and 65.5% for WHtR. Cross-validation analysis revealed that BMI-z and WHtR correctly classified 84% of individuals (kappa score = 0.671, 95% CI 0.55, 0.79). The sensitivity of the cut-points suggests that 89.3% of individuals were correctly classified as being at risk with only 10.7% misdiagnosed whereas the specificity of the cut-points indicated that 77.8% of individuals were correctly identified as being healthy with 22.2% of individuals incorrectly diagnosed as being at risk. Conclusions Findings suggest that WHtR provides similar cardiometabolic risk estimates to age and sex adjusted BMI. [ABSTRACT FROM AUTHOR]

Introduction:The aim of this investigation was to examine the impact high-intensity interval training (HIIT) on serum insulin-like growth factor-I (IGF-I) in active compared with sedentary aging men. Methods:22 lifetime sedentary (SED; 62 ± 2 years) and 17 masters’ athletes (LEX; 60 ± 5 years) were recruited to the study. As HIIT requires preconditioning exercise in sedentary cohorts, the study required three assessment phases; enrollment (phase A), following preconditioning exercise (phase B), and post-HIIT (phase C). Serum IGF-I was determined by electrochemiluminescent immunoassay. Results:IGF-I was higher in LEX compared to SED at baseline (p = 0.007, Cohen’sd = 0.91), and phase B (p = 0.083, Cohen’sd = 0.59), with only a small difference at C (p = 0.291, Cohen’sd = 0.35). SED experienced a small increase in IGF-I following preconditioning from 13.1 ± 4.7 to 14.2 ± 6.0 μg·dl−1(p = 0.376, Cohen’sd = 0.22), followed by a larger increase post-HIIT (16.9 ± 4.4 μg·dl−1), which was significantly elevated compared with baseline (p = 0.002, Cohen’sd = 0.85), and post-preconditioning (p = 0.005, Cohen’sd = 0.51). LEX experienced a trivial changes in IGF-I from A to B (18.2 ± 6.4 to 17.2 ± 3.7 μg·dl−1[p = 0.538, Cohen’sd = 0.19]), and a small change post-HIIT (18.4 ± 4.1 μg·dl−1[p = 0.283, Cohen’sd = 0.31]). Small increases were observed in fat-free mass in both groups following HIIT (p < 0.05, Cohen’sd = 0.32–0.45). Conclusions:In conclusion, HIIT with preconditioning exercise abrogates the age associated difference in IGF-I between SED and LEX, and induces small improvements in fat-free mass in both SED and LEX. [ABSTRACT FROM PUBLISHER]