Differences in Hip and Knee Running Moments across Female Pubertal Development

Purpose This study aimed to investigate whether knee and hip running moments differ across stages of female pubertal development. Methods This was a cross-sectional study comparing the barefoot running moments of 91 prepubertal (n = 31, Tanner stage I), early/midpubertal (n = 30, Tanner stages II and III), and late/postpubertal (n = 30, Tanner stages IV and V) girls. External peak moments for knee abduction (KAbM), knee adduction (KAM), knee flexion (KFM), and knee internal rotation (KIRM) were analyzed. Secondary measures of hip adduction moment at the time of peak KAbM and hip flexion moment at the time of peak KFM were also derived. Between-group differences were analyzed using a series of one-way ANOVAs and ANCOVAs. Results At the knee, the late/postpubertal girls displayed a higher peak KFM and KAM compared with the prepubertal group (P 0.05). At the hip, both the late/postpubertal (P = 0.03) and early/midpubertal girls (P = 0.039) ran with a lower hip adduction moment at the time of peak KAbM than the prepubertal girls. The hip flexion moment at the time of peak KFM in late/postpubertal girls was also significantly lower than both the early/mid- and prepubertal girls (P

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Protocol for Objective Measurement of Infants’ Physical Activity using Accelerometry

Purpose This study aimed to evaluate methods for infants' physical activity measurement based on accelerometry, including the minimum number of measurement days and placement of a wrist or ankle device. We also evaluated the acceptability of the device among infants and mothers. Methods A cross-sectional mixed-methods study was conducted on a convenience sample of 90 infants. Physical activity was measured using the Actigraph GT3X+ accelerometer placed on the wrist and/or ankle for 7 consecutive days (worn for 24 h), and a qualitative interview was performed to verify acceptability. The intraclass correlation coefficient (ICC) method and the Bland and Altman's dispersion diagram were used to verify the minimum number of measurement days. All analyses were stratified by walking status. Results The mean (SD) age was 12.9 (1.70) months; the mean acceleration varied between 25.8 mg (95% confidence interval (CI), 14.3–52.7) and 27.3 mg (95% CI, 17.9–44.5) using the wrist placement, and between 24.9 mg (95% CI, 10.6–48.4) and 26.2 mg (95% CI, 11.7–65.6) using the ankle placement. The ICC results showed a lower acceleration variability between days among infants incapable of walking; they achieved an ICC of 0.80 with 1 d of measurement in both placements. Among those capable of walking, the minimum number of days to achieve an ICC of 0.80 was 2 d measured at the wrist (0.85; 95% CI, 0.71–0.93) and 3 d measured at the ankle (0.92; 95% CI, 0.84–0.96). The qualitative results pointed to the wrist placement as the preferred placement among the overall sample. Conclusions Two and three measurement days with the accelerometer placed on the wrist and ankle, respectively, seemed to adequately represent a week of measurement. The accelerometer placed on the wrist had better acceptance by the infants and mothers.

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Effect of Beta-blocker Treatment on V˙O2peak in Patients with Heart Failure

Purpose In addition to prolonged life and reduced hospitalization rates, it is currently unclear whether beta-blocker (BB) treatment modulates peak oxygen consumption (V˙O2peak), a hallmark of exercise capacity, in patients with heart failure (HF). The main aim of this study is to determine the effect of BB treatment on V˙O2peak in HF patients. Methods We conducted a systematic search of MEDLINE, Scopus, and Web of Science since their inceptions until March 2017 for randomized controlled trials (RCT) assessing the effect of BB treatment on V˙O2peak in chronic HF patients. A meta-analysis was performed to ascertain the standardized mean difference (SMD) between the effects of BB and placebo treatment on V˙O2peak. Secondary outcomes included peak exercise performance and New York Health Association functional class. Subgroup and meta-regression analyses assessed potential moderating factors. Results Fourteen RCT met the inclusion criteria (overall n = 616). Interventions comprised BB (n = 324) or placebo (n = 292) administration lasting 3 to 24 months. Concomitant reported medication did not differ between HF patients assigned to BB and placebo groups. After data pooling, V˙O2peak was preserved with BB compared with placebo treatment (SMD, −0.04; 95% confidence interval (CI), −0.20 to 0.12; P = 0.61); heterogeneity among studies was not detected (I2 = 0%, P = 0.88). Peak exercise performance was not altered (SMD, 0.02; 95% CI, −0.16 to 0.20; P = 0.85), whereas New York Health Association functional class was reduced with BB compared with placebo (SMD, −0.54; 95% CI, −0.90 to −0.18; P = 0.003). Conclusions According to evidence from RCT, prolonged BB (B1-selective or nonselective) treatment does not affect V˙O2peak but improves functional status in HF patients.

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Synchronizing Gait with Cardiac Cycle Phase Alters Heart Rate Response during Running

Timing foot strike to occur in synchrony with cardiac diastole may reduce left ventricular afterload and promote coronary and skeletal muscle perfusion. Purpose This study aimed to assess heart rate (HR) and metabolic responses to running when foot strikes are timed to occur exclusively during 1) the systolic phase of the cardiac cycle or 2) the diastolic phase. Methods Ten elite male distance runners performed a testing session on a treadmill at 4.72 m·s−1 while matching their steps to an auditory tone and wearing a chest strap that transmitted accelerometer and ECG signals. Testing comprised eight prompted 3-min stages, where a real-time adaptive auditory tone guided subjects to step with each ECG R-wave (systolic stepping) or alternatively, at 45% of each R-R interval (diastolic stepping), followed by a 3-min unprompted control stage. Metabolic variables were measured continuously. Results HR (P

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Benefits of Resistance Training with Blood Flow Restriction in Knee Osteoarthritis

Purpose Evaluate the effects of a low-intensity resistance training (LI-RT) program associated with partial blood flow restriction on selected clinical outcomes in patients with knee osteoarthritis (OA). Methods Forty-eight women with knee OA were randomized into one of the three groups: LI-RT (30% one repetition maximum [1-RM]) associated (blood flow restriction training [BFRT]) or not (LI-RT) with partial blood flow restriction, and high-intensity resistance training (HI-RT, 80% 1-RM). Patients underwent a 12-wk supervised training program and were assessed for lower-limb 1-RM, quadriceps cross-sectional area, functionality (timed-stands test and timed-up-and-go test), and disease-specific inventory (Western Ontario and McMaster Universities Osteoarthritis Index [WOMAC]) before (PRE) and after (POST) the protocol. Results Similar within-group increases were observed in leg press (26% and 33%, all P

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Monitoring Training and Performance in Athletes

No abstract available

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Predictive Modeling of Hamstring Strain Injuries in Elite Australian Footballers

Purpose Three of the most commonly identified hamstring strain injury (HSI) risk factors are age, previous HSI, and low levels of eccentric hamstring strength. However, no study has investigated the ability of these risk factors to predict the incidence of HSI in elite Australian footballers. Accordingly, the purpose of this prospective cohort study was to investigate the predictive ability of HSI risk factors using machine learning techniques. Methods Eccentric hamstring strength, demographic and injury history data were collected at the start of preseason for 186 and 176 elite Australian footballers in 2013 and 2015, respectively. Any prospectively occurring HSI were reported to the research team. Using various machine learning techniques, predictive models were built for 2013 and 2015 within-year HSI prediction and between-year HSI prediction (2013 to 2015). The calculated probabilities of HSI were compared with the injury outcomes and area under the curve (AUC) was determined and used to assess the predictive performance of each model. Results The minimum, maximum, and median AUC values for the 2013 models were 0.26, 0.91, and 0.58, respectively. For the 2015 models, the minimum, maximum and median AUC values were, correspondingly, 0.24, 0.92, and 0.57. For the between-year predictive models the minimum, maximum, and median AUC values were 0.37, 0.73, and 0.52, respectively. Conclusions Although some iterations of the models achieved near perfect prediction, the large ranges in AUC highlight the fragility of the data. The 2013 models performed slightly better than the 2015 models. The predictive performance of between-year HSI models was poor however. In conclusion, risk factor data cannot be used to identify athletes at an increased risk of HSI with any consistency.

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