Comparing the Force-Time Characteristics Between Countermovement and Assisted Countermovement Jump with Different...

Area of Science:

• Biomechanics
• Sports Science
• Human Movement Analysis

Background:

• Conflicting findings exist regarding landing impact force (LIF) in countermovement jumps (CMJ) versus assisted countermovement jumps (ACMJ).
• Landing strategies (soft vs. stiff) may influence LIF, impacting neuromuscular adaptations.

Purpose of the Study:

• To compare LIF between CMJ and ACMJ.
• To investigate the effect of soft and stiff landing strategies on LIF during CMJ and ACMJ.
• To understand the influence of varying assistance levels on jump performance and landing mechanics.

Main Methods:

• Thirteen resistance-trained athletes performed CMJ and ACMJ at 60-90% bodyweight assistance.
• Participants employed either soft or stiff landing strategies on a force plate.
• Jump height, propulsion duration, peak propulsion force, and LIF were measured.

Main Results:

• Jump height significantly increased with greater assistance in ACMJ for both landing types.
• Propulsion duration significantly decreased with greater assistance in ACMJ.
• Peak and mean propulsion forces decreased with increased assistance in ACMJ.
• LIF was significantly greater in ACMJ with stiff landings compared to soft landings, particularly at higher assistance levels.

Conclusions:

• Assistance in ACMJ enhances jump height and reduces propulsion duration.
• Stiff landings in ACMJ, especially with higher assistance, result in greater LIF.
• The increased LIF in stiff-landing ACMJ is likely due to higher jump height and landing velocity.