Number of Directional Changes Alters the Physiological, Perceptual, and Neuromuscular Responses of Netball Players During Intermittent Shuttle Running

This study investigated whether an increased number of changes in direction altered the metabolic, cardiovascular, perceptual and neuromuscular responses to intermittent shuttle running. Using a randomized crossover design, ten female netball players completed 30 min of intermittent shuttle running over a 10 m (ISR10) and 20 m (ISR20) linear course. Measures of expired air, heart rate (HR), RPE, blood lactate concentration ([BLa]) and peak torque of knee extensors and flexors were measured. Differences (% ± 90% CL) in VO2 (1.5 ± 5.6%) was unclear between conditions, while HR was possibly higher (1.5 ± 2.5%) and [BLa] very likely lower in ISR20 compared to ISR10 (-32.7 ± 9.9%). RPE was likely lower in the ISR20 compared to the ISR10 condition at 15 (-5.0 ± 5.0%) and mosly likely lower at 30 min (-9.4 ± 2.0%). Sprint times over 20 m were likely slower during ISR20 at mid (3.9 ± 3.2%) but unclear post (2.1 ± 5.4%). Changes in muscle function were not different between ISR10 and ISR20 conditions for knee extension (-0.2 ± 0.9%) but were likely different for knee flexion (-5.7 ± 4.9%). More directional changes during shuttle running increases the physiological and perceptual load on female athletes that also causes a greater reductions in knee extensor torque. These findings have implications for the effective conditioning and injury prevention of female team sport athletes.