当前位置： SCI文献检索 > JOURNAL OF STRENGTH AND CONDITIONING RESEARCH期刊下所有文献 > Effect of Ankle Joint Contact Angle and Ground Contact Time on Depth Jump Performance.

Effect of Ankle Joint Contact Angle and Ground Contact Time on Depth Jump Performance.

Abstract：

:Athletes often need to both jump high and get off the ground quickly, but getting off the ground quickly can decrease the vertical ground reaction force (VGRF) impulse, impeding jump height. Energy stored in the muscle-tendon complex during the stretch-shortening cycle (SSC) may mitigate the effects of short ground contact times (GCTs). To take advantage of the SSC, several coaches recommend "attacking" the ground with the foot in a dorsiflexed (DF) position at contact. However, the efficacy of this technique has not been tested. This investigation tested the hypotheses that shorter GCTs would lead to smaller vertical depth jump heights (VDJH), and that this difference could be mitigated by instructing the athletes to land in a DF as opposed to a plantar flexed (PF) foot position. Eighteen healthy junior college athletes performed depth jumps from a 45-cm box onto force platforms under instruction to achieve one of the 2 objectives (maximum jump height [hmax] or minimal GCT [tmin]), with one of the 2 foot conditions (DF or PF). These variations created 4 distinct jump conditions: DF-hmax, DF-tmin, PF-hmax, and PF-tmin. For all variables examined, there were no significant interactions. For all 4 conditions, the ankle was PF during landing, but the DF condition was 28.87% less PF than the PF condition. The tmin conditions had a 23.48% shorter GCT than hmax. There were no significant main effects for jump height. The peak impact force for tmin was 22.14% greater than hmax and 19.11% greater for DF compared with PF conditions. A shorter GCT did not necessitate a smaller jump height, and a less PF foot did not lead to improvements in jump height or contact time during a depth jump from a 45-cm box. The same jump height was attained in less PF and shorter GCT conditions by larger impact forces. To decrease contact time while maintaining jump height, athletes should be instructed to "get off the ground as fast as possible." This cue seems to be more important than foot position. However, it should be acknowledged that this technique leads to larger impact forces, which should be considered when prescribing the number of foot contacts in a plyometrics program. The ability of athletes to truly land in a DF position during depth jumps is questioned and needs further investigation.

journal_name

J Strength Cond Res

journal_title

Journal of strength and conditioning research

authors

Phillips JH,Flanagan SP

doi

10.1519/JSC.0000000000000980

subject

Has Abstract

pub_date

2015-11-01 00:00:00

pages

3143-8

issue

eissn

1064-8011

issn

1533-4287

journal_volume

pub_type

杂志文章

在线工具

Effect of Ankle Joint Contact Angle and Ground Contact Time on Depth Jump Performance.