The effects of a subsequent jump on the knee abduction angle during the early landing phase

Abstract

Background: A double-leg landing with or without a subsequent jump is commonly used to evaluate the neuromuscular control of knee abduction. However, the differences in frontal plane knee biomechanics between landings with and without a subsequent jump are not well known. The purpose of the present study was to investigate the effects of a subsequent jump on knee abduction, including during the early landing phase, in female and male subjects.

Methods: Twenty-one female subjects and 21 male subjects participated. All subjects performed drop landing task (a landing without a subsequent jump) and drop vertical jump task (a landing with a subsequent jump). The subjects landed from a 30-cm height. In drop vertical jump, the subjects also performed a maximum vertical jump immediately after landing. The knee abduction angle and moment were analyzed using a 3D motion analysis system. A two-way analysis of variance (task × time) was performed to examine the effects of a subsequent jump on the knee abduction angle during the early landing phase in female and male subjects. Another two-way analysis of variance (task × sex) was performed to compare peak knee abduction angles and moments.

Results: In female subjects, the knee abduction angle was significantly greater during drop vertical jump than during drop landing, as measured 45 to 80 ms after initial contact (P < 0.05). Significant task-dependent effects in the peak knee abduction angle (P = 0.001) and the abduction moment (P = 0.029) were detected. The peak knee abduction angle and the abduction moment were greater during drop vertical jump than during drop landing.

Conclusions: Subsequent jumps cause greater knee abduction during the early landing phase only in female subjects. This finding may relate to the sex discrepancy in non-contact anterior cruciate ligament injuries. Additionally, the presence of a subsequent jump significantly increases the peak knee abduction angle and the peak knee abduction moment during landings. Therefore, compared with a landing task without a subsequent jump (drop landing), a landing task with a subsequent jump (drop vertical jump) may be advantageous for screening for knee abduction control, especially in female athletes.

Keywords: Anterior cruciate ligament; Biomechanics; Knee injury; Prevention; Risk factor; Sex difference.

Conflict of interest statement

Ethics approval and consent to participate

All subjects read and signed informed consent forms prior to their inclusion in the present study. This study was approved by the Hokkaido University Institutional Review Board (Approval number: 11–55).

Consent for publication

The subject who is showed in figure has read and signed a consent form for publication.

Competing interests

The authors declare that they have no competing interests.

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Figures

Fig. 1

Marker placement

Fig. 2

The two landing tasks. In drop landing (DL, landings without a subsequent jump), the subjects drop off a 30-cm high box and land on the force plates (a). During drop vertical jump (DVJ, landings with a subsequent jump), the subjects drop off the box and then jump immediately after landing (b)

Fig. 3

Knee abduction angles during the early landing phase for female (a) and male subjects (b) and peak knee abduction angles during the landing phase (c). *indicates a significant difference (P < 0.05). IC, initial contact

Fig. 4

Knee flexion angles during the early landing phase for female (a) and male subjects (b) and the peak knee abduction angle measured during the landing phase (c). *indicates a significant difference (P < 0.05). IC, initial contact

Fig. 5

Peak knee abduction (a) and flexion moments (b). *indicates a significant difference between DVJ and DL, as detected by the post hoc test (P < 0.05)