Differences Between Bimodal and Unimodal Force-time Curves During Countermovement Jump

Abstract

This study aimed to explore the biomechanical differences between single and double peak ground reaction force-time curves during the countermovement jump with respect to kinematics, kinetics, and coordination of the lower extremities. Twenty-five college students were stratified into a single peak curve group and a double peak curve group. Eight infrared cameras and two force platforms were synchronized to collect the data. Independent t-tests were performed with groups for each dependent kinematic, kinetic and time of the joint extensor concentric contraction variable. Repeated one-way analysis of variance measurements were performed for the time of the ankle, knee and hip extensor concentric contraction in each group. The double peak curve was associated with larger jump height, reactive strength index modified, rate of force development, impulse, hip, knee and ankle flexion, extension angular displacement, and hip and knee moments (p<0.05). The double peak curve group revealed a better hip, knee and ankle (proximal to distal) timing of extensor concentric contractions sequence of the lower extremities during the countermovement jump (p<0.05). The double peak curve group exhibited a more effective countermovement jump movement with respect to biomechanics compared to the single peak curve group.

Low-Pass Filter Effects on Metrics of Countermovement Vertical Jump Performance

“…What differed among these methods was how the low-pass cutoff frequency was determined for each trial. For the 50-Hz method, a cutoff frequency of 50 Hz was selected because of its widespread use in CMVJ studies (2,4,16,18,38). The visual inspection 1 method determined the cutoff frequency based on a subjective visual analysis of the signal frequency content.…”

“…Still, numerous CMVJ studies have analyzed raw GRF data or failed to indicate whether filtered or raw GRF data were analyzed (32,33,37,39,47) despite the possible influence of filtering on study results. In CMVJ studies using a low-pass filter, cutoff frequencies of 10 Hz (46), 12 Hz (24), 16 Hz (5), 17 Hz (30,34), 30 Hz (15), 40 Hz (44,45), and 50 Hz (2,16,18,38) have been reported. Some CMVJ studies provide justification for the selected cutoff frequency, such as plotting the frequency content of the recorded signals and subjectively estimating the primary frequency band (15,16), use of an objective determination method (34,45), or citing its use in a previous study (3,30).…”

The Influence of Repeated Drop Jump Training on Countermovement Jump Performance

“…The continuous concentric contraction and eccentric contraction of the muscles are called the stretch-shortening cycle (SSC) [2]. Past studies have found that using the SSC elastic energy mechanism increases the strength, speed, and muscle activation of the CMJ eccentric phase and increases the jump height during the CMJ concentric phase [3]. Thus, applying the SSC mechanism can enhance the muscle strength of the lower extremities and the jumping height in the CMJ to improve athletic perfor-mance.…”

“…Thus, applying the SSC mechanism can enhance the muscle strength of the lower extremities and the jumping height in the CMJ to improve athletic perfor-mance. In addition, previous studies have found that drop jumps (DJs) are an effective plyometric training (PT) and SSC training method, currently being widely used to improve jumping ability and leg strength to improve athletic performance [3,4]. Therefore, DJ training can enhance the SSC mechanism to improve CMJ performance.…”

The Effect of Repetitive Drop Jumps among Different Heights on Bilateral Asymmetry of Countermovement Jumps

“…The countermovement jump (CMJ) is a dynamic plyometric training method for multijoint movement of the lower extremities, which rapidly develops strength through higher eccentric force to increase the concentric force development of the stretching-shortening cycle (SSC) mechanism [1]. The drop jump (DJ) is widely used to increase muscle strength and improve the SSC ability as an effective plyometric training method [2].…”