Validity of field assessments to predict peak muscle power in preschoolers.

Field-based fitness assessments are time- and cost-efficient. However, no studies to date have reported the predictive value of field-based musculoskeletal fitness assessments in preschoolers. The purpose of this study was to determine the validity of 2 field assessments to predict peak muscle power in preschool-aged children. Four-hundred and nineteen 3- to 5-year olds participated (208 girls, 211 boys; mean age: 4.5 ± 0.9 years). Peak power (PP) was evaluated using a modified 10-s Wingate protocol as the criterion standard. Standing long-jump was measured in inches to the back of the heel using a 2-footed takeoff and landing. Shuttle-run time was measured using a shuttle-run protocol, which required children to sprint 50 feet (15.2 m), pick up a small block, and sprint back, with time measured to the closest tenth of a second. Regression modelling was used to calculate the predictive power of each field-based measurement, adjusting for weight (kg), age, and sex. Both standing long-jump distance and shuttle-run time were significantly correlated with PP (r = 0.636, p < 0.001, and r = -0.684, p < 0.001, respectively). Linear regression analysis determined that a child's PP can be predicted from the child's weight, age, and sex and either standing long-jump or shuttle-run time (adjusted R2 = 0.79, p < 0.001, and 0.81, p < 0.001, respectively). The standing long-jump and the Bruininks Oseretsky Test of Motor Proficiency 2nd Edition shuttle-run are both significant predictors of peak muscle power in preschool children. Either measure can be used as a cost- and time-efficient estimate of musculoskeletal fitness in preschoolers.

Effect of jumping interval training on neuromuscular and physiological parameters: a randomized controlled study.

This study analyzed the effect of 4 weeks of jumping interval training (JIT), included in endurance training, on neuromuscular and physiological parameters. Eighteen recreational runners, randomized in control and experimental groups, performed 40 min of running at 70% of velocity at peak oxygen uptake, for 3 times per week. Additionally, the experimental group performed the JIT twice per week, which consisted of 4 to 6 bouts of continuous vertical jumps (30 s) with 5-min intervals. Three days before and after the training period, the countermovement (CMJ) and continuous jump (CJ30), isokinetic and isometric evaluation of knee extensors/flexors, progressive maximal exercise, and submaximal constant-load exercise were performed. The JIT provoked improvement in neuromuscular performance, indicated by (i) increased jump height (4.7%; effect size (ES) = 0.99) and power output (≈ 3.7%; ES ≈ 0.82) of CMJ and rate of torque development of knee extensors in isometric contraction (29.5%; ES = 1.02); (ii) anaerobic power and capacity, represented by the mean of jump height (7.4%; ES = 0.8), and peak power output (PPO) (5.6%; ES = 0.73) of the first jumps of CJ30 and the mean of jump height (10.2%, ES = 1.04) and PPO (9.5%, ES = 1.1), considering all jumps of CJ30; and (iii) aerobic power and capacity, represented by peak oxygen uptake (9.1%, ES = 1.28), velocity at peak oxygen uptake (2.7%, ES = 1.11), and velocity corresponding to the onset of blood lactate accumulation (9.7%, ES = 1.23). These results suggest that the JIT included in traditional endurance training induces moderate to large effects on neuromuscular and physiological parameters.