Background

While mini-trampolines have been used among a variety of groups including children as an intervention tool, the motor behavior children adopt while hopping on this soft, elastic surface is unknown. Identifying coordinative structures and their stability for hopping on a mini-trampoline is imperative for recommending future interventions and determining appropriateness to populations with motor dysfunctions.

Research question

Do children demonstrate similar biomechanical and coordination patterns as adults while hopping on a mini-trampoline?

Methods

Fifteen adults aged 18–35 years and 14 children aged 7–12 years completed bouts of continuous two-legged hopping in-place on a stiff surface for 10 s at a time and on a mini-trampoline for 30 s at a time. 3-D motion capture tracked whole-body movement. We evaluated whole-body vertical stiffness as a ratio of peak vertical force and peak vertical displacement, as well as spatiotemporal parameters of hopping. Coordinative structures were evaluated as continuous relative phase angles of the foot, shank, thigh, and pelvis segments.

Results and significance

Adults did not modify whole-body vertical stiffness on a mini-trampoline, while children increased whole-body vertical stiffness to compensate for the reduced surface stiffness. Both groups conserved the coordinative structure for hopping on a mini-trampoline by modulating hopping cycle timing. Moreover, children hopped with an adult-like coordinative structure, but required greater shank-thigh and thigh-pelvis out-of-phase motion. However, the consistency of their coordination was diminished compared to adults. Children aged 7–12 years old have formed a stable coordinative structure for spring-mass center-of-mass dynamics that is preserved on this soft, elastic surface. However, children might be developing control strategies for preferred whole-body vertical stiffness, particularly when required to dampen peak vertical forces. These results highlight the importance of evaluating the emerging motor behavior to manipulated environmental constraints, particularly when considering the utility and appropriateness of mini-trampoline interventions for children with motor dysfunctions.

中文翻译：

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成人和儿童在小型蹦床上跳跃的协调动力学

背景

虽然微型蹦床已在包括儿童在内的各种人群中使用，作为干预工具，但尚不清楚儿童在跳动于此柔软而有弹性的表面时所采取的运动行为。识别协调结构及其在小型蹦床上跳跃时的稳定性对于推荐未来的干预措施并确定对运动功能障碍人群的适用性至关重要。

研究问题

儿童在跳上小型蹦床时是否表现出与成年人相似的生物力学和协调方式？

方法

15名18至35岁的成年人和14名7至12岁的儿童在坚硬的表面上一次连续10 s跳完两脚，在微型蹦床上一次30 s跳完。3-D运动捕捉可跟踪全身运动。我们以峰值垂直力和峰值垂直位移之比以及跳跃的时空参数来评估全身垂直刚度。协调结构被评估为脚，小腿，大腿和骨盆段的连续相对相位角。

结果与意义

成人没有改变小型蹦床的全身垂直刚度，而儿童则增加了全身垂直刚度以补偿降低的表面刚度。两组都通过调节跳跃周期的时间来保持在迷你蹦床上跳跃的协调结构。此外，孩子们跳起了成年人般的协调结构，但需要更大的小腿和大腿骨盆异相运动。但是，与成年人相比，他们协调的一致性降低了。7至12岁的儿童已经形成了稳定的协调结构，用于弹簧质量质心动力学，并保留在此柔软而有弹性的表面上。但是，儿童可能正在开发控制策略，以获得更好的全身垂直刚度，尤其是在需要减小峰值垂直力时。