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This study compared the effects of six warm-up modalities on peak power output (PPO) during the high-pull exercise. Nine resistance-trained males completed six trials using different warm-ups: highpull specific (HPS), cycle, whole body vibration (WBV), cycle+HPS, WBV+HPS and a control. Intramuscular temperature (Tm) was increased by 2°C using WBV or cycling. PPO, Tm and electromyography (EMG) were recorded during each trial. Two high-pulls were performed prior to and 3 min after participants completed the warm-up. The greatest increase in PPO occurred with HPS (232.8 ± 89.7 W, P < 0.001); however, this was not different to combined warm-ups (cycle+HPS 158.6 ± 121.1 W; WBV +HPS 177.3 ± 93.3 W, P = 1.00). These modalities increased PPO to a greater extent than those that did not involve HPS (all P < 0.05). HPS took the shortest time to complete, compared to the other conditions (P < 0.05). EMG did not differ from pre to post warm-up or between modalities in any of the muscles investigated. No change in Tm occurred in warm-ups that did not include cycling or WBV. These results suggest that a movement-specific warm-up improves performance more than temperature- related warm-ups. Therefore, mechanisms other than increased muscle temperature and activation may be important for improving short-term PPO. [ABSTRACT FROM AUTHOR]

The aim of this study was to determine the muscle activity and onset time of hip extensors during a closed kinetic chain exercise (deadlift) at sub-maximal loads of 30%, 40%, 50%, and 75% of one repetition maximum (1RM). Twelve healthy males with at least three years of resistance training experience volunteered for the study. Biceps femoris (BF) and gluteus maximus (GM) muscle activity, onset time, peak and mean power were measured during the concentric phase of the deadlift. There was no main effect (p > 0.05) or no interaction effect for the onset time in BF and GM and for each load BF and GM had similar muscle activity. Increasing the external load during deadlift had no adverse effect on the relative onset time and it did not promote BF onset to occur before GM onset, thus both muscles were simultaneously activated, which should not compromise a delay in GM. [ABSTRACT FROM AUTHOR]

The purpose of this study was to quantify the inter-session reliability of force–velocity–power profiling and estimated maximal strength in youth. Thirty-six males (11–15 years old) performed a ballistic supine leg press test at five randomized loads (80%, 100%, 120%, 140%, and 160% body mass) on three separate occasions. Peak and mean force, power, velocity, and peak displacement were collected with a linear position transducer attached to the weight stack. Mean values at each load were used to calculate different regression lines and estimate maximal strength, force, velocity, and power. All variables were found reliable (change in the mean [CIM] = − 1 to 14%; coefficient of variation [CV] = 3–18%; intraclass correlation coefficient [ICC] = 0.74–0.99), but were likely to benefit from a familiarization, apart from the unreliable maximal force/velocity ratio (CIM = 0–3%; CV = 23–25%; ICC = 0.35–0.54) and load at maximal power (CIM = − 1 to 2%; CV = 10–13%; ICC = 0.26–0.61). Isoinertial force–velocity–power profiling and maximal strength in youth can be assessed after a familiarization session. Such profiling may provide valuable insight into neuromuscular capabilities during growth and maturation and may be used to monitor specific training adaptations. [ABSTRACT FROM PUBLISHER]

The aim of the study was to validate the self-report Multimedia Activity Recall for Children and Adolescents (MARCA) against accelerometry for the assessment of physical activity in New Zealand children. Participants (n = 716, 10–18 years) recalled 3–4 days of activity using the MARCA and underwent a partially overlapping 7-day accelerometry protocol during a national survey. Spearman correlation coefficients (ρ) assessed the association between accelerometer-derived counts per minute and MARCA-derived physical activity level and time in locomotion. Both data sources estimated time spent in light and moderate–vigorous physical activity. Association and agreement between methods for light physical activity and moderate–vigorous physical activity was assessed using correlations and Bland–Altman plots respectively, and pairedt-tests conducted. Accelerometer-derived activity counts were moderately correlated with both MARCA-derived physical activity level and locomotion (ρ = 0.38,P < 0.0001). The correlation between methods was –0.14 for light physical activity and 0.28 for moderate–vigorous physical activity (P < 0.0001). The MARCA overestimated moderate–vigorous physical activity compared with accelerometry (120 min,P < 0.0001), which increased as moderate–vigorous physical activity time increased. Some sex and ethnicity (Māori [indigenous] versus non-Māori) differences were observed. Overall, the MARCA indicated moderate validity for assessment of physical activity level, locomotion and moderate–vigorous physical activity and poor validity for assessment of light physical activity. This was comparable to other self-report tools. The MARCA has utility for future large-scale research. [ABSTRACT FROM PUBLISHER]

Kinematic studies have shown that fast bowlers have run-up velocities, based on centre of mass velocity calculations, which are comparable to elite javelin throwers. In this study, 34 fast bowlers (22.3 ± 3.7 years) of premier grade level and above were tested using a three-dimensional (3-D) motion analysis system (240 Hz). Bowlers were divided into four speed groups: slow-medium, medium, medium-fast, and fast. The mean centre of mass velocity at back foot contact (run-up speed) was 5.3 ± 0.6 m/s. Centre of mass velocity at back foot contact was significantly faster in the fastest two bowling groups compared to the slow-medium bowling group. In addition, stepwise multiple regression analysis showed that the centre of mass deceleration over the delivery stride phase was the strongest predictor of ball speed in the faster bowling groups. In conclusion, centre of mass kinematics are an important determinant of ball speed generation in fast bowlers. In particular, bowlers able to coordinate their bowling action with periods of centre of mass deceleration may be more likely to generate high ball speed. [ABSTRACT FROM AUTHOR]