Effect of Box Height on Box Jump Performance in Elite Female Handball Players.

ABSTRACT: Koefoed, N, Dam, S, and Kersting, UG. Effect of box height on box jump performance in elite female team handball players. J Strength Cond Res 36(2): 508-512, 2022-This study aimed at investigating whether a link exists between performance in a countermovement jump and the height of the box an athlete could successfully jump onto. Furthermore, it was investigated whether the height of the box influences the takeoff. Ten, elite, female team, handball players were recruited for the study (age: 20.9 ± 3.2 years; height: 174.7 ± 7.6 cm; mass: 73.8 ± 6.7 kg). Subjects performed 3 maximal countermovement jumps. Subsequently, subjects jumped onto boxes of increasing height until they could no longer successfully jump onto the box. Subjects then performed 3 box jumps with maximal intention to boxes corresponding to 70% of their maximal center of mass displacement (LOW) and 90% of their maximal achieved box height (HIGH). Finally, subjects completed another 3 maximal countermovement jumps. There was no relationship between the maximal center of mass displacement in countermovement jumps and the maximal achievable box jump height (r2 = 0.35; p = 0.071). Between jumps to LOW and HIGH boxes, there were no differences in the chosen variables, peak force (-156 ± 390 N; p = 0.239), peak power (25 ± 236 W; p = 0.747), peak center of mass displacement (0.003 ± 0.039 m; p = 0.840), peak rate of force development (-3.055 ± 6264 N·s-1; p = 0.157), and concentric time to takeoff (0.005 ± 0.044 seconds; p = 0.721). Because no differences could be found, the added risk of failure leading to injury and the limited possibilities of improving specific landing technique with low impact when jumping to high boxes in training cannot be justified.

Repeated Bout Rate Enhancement Is Elicited by Various Forms of Finger Tapping.

Voluntary rhythmic movements, such as, for example, locomotion and other cyclic tasks, are fundamental during everyday life. Patients with impaired neural or motor function often take part in rehabilitation programs, which include rhythmic movements. Therefore, it is imperative to have the best possible understanding of control and behaviour of human voluntary rhythmic movements. A behavioural phenomenon termed repeated bout rate enhancement has been established as an increase of the freely chosen index finger tapping frequency during the second of two consecutive tapping bouts. The present study investigated whether the phenomenon would be elicited when the first bout consisted of imposed passive finger tapping or air tapping. These two forms of tapping were applied since they can be performed without descending drive (passive tapping) and without afferent feedback related to impact (air tapping) - as compared to tapping on a surface. Healthy individuals (n = 33) performed 3-min tapping bouts separated by 10 min rest. Surface electromyographic, kinetic, and kinematic data were recorded. Supportive experiments were made to measure, for example, the cortical sensory evoked potential (SEP) response during the three different forms of tapping. Results showed that tapping frequencies in the second of two consecutive bouts increased by 12.9 ± 14.8% (p < 0.001), 9.9 ± 6.0% (p = 0.001), and 16.8 ± 13.6% (p = 0.005) when the first bout had consisted of tapping, passive tapping, and air tapping, respectively. Rate enhancement occurred without increase in muscle activation. Besides, the rate enhancements occurred despite that tapping, as compared with passive tapping and air tapping, resulted in different cortical SEP responses. Based on the present findings, it can be suggested that sensory feedback in an initial bout increases the excitability of the spinal central pattern generators involved in finger tapping. This can eventually explain the phenomenon of repeated bout rate enhancement seen after a consecutive bout of finger tapping.

Peak Power Output in Loaded Jump Squat Exercise is Affected by Set Structure.

A priority in strength and power exercise might be to train with as high quality as possible for the shortest possible duration. In this context, peak power output could reflect quality. Designing an exercise session as a cluster set structure, as compared to a traditional set structure, may be a way to obtain higher peak power output in the session. But it is unknown whether that is obtainable for non-elite individuals performing loaded jump squat exercise. The aim of the present study was therefore to test the hypothesis that peak power output would be highest in a jump squat exercise session, which was structured with cluster sets, as compared to traditional sets. Ten individuals (2 women, 8 men; 26.5 ± 4.8 years, 1.81 ± 0.08 m, 90.9 ± 13.2 kg) performed two loaded jump squat exercise sessions structured with cluster sets and traditional sets, respectively. The sessions were performed on two separate days, in counterbalanced order. The position of the barbell was used to calculate derived values including peak power output. Values calculated as averages across the entire exercise sessions showed peak power output to be 178 ± 181 W, corresponding to 4.1% ± 4.9%, higher in the session with cluster set structure, as compared to the session with traditional set structure (p = 0.005). It was concluded that for non-elite individuals, peak power output was approximately 4% higher in a loaded jump squat exercise session structured with cluster sets as compared to an exercise session structured with traditional sets.