Speed and Distance Redistribution-Lower Limb Power Strategy in Single-Leg-Approach Jumps

Area of Science:

• Biomechanics
• Sports Science
• Human Movement Analysis

Background:

• The approach phase in running jumps is crucial for performance.
• Understanding how approach kinematics influence jump kinetics is essential for optimizing athletic movements.
• Previous research has not fully elucidated the joint-level power strategies during single-leg approach running jumps.

Purpose of the Study:

• To systematically investigate the influence of approach kinematics (speed and distance) on kinetics and power production during the approach to running jumps with a single leg (ARJSL).
• To analyze how different approach strategies affect jump height, touchdown velocity, reactive strength index, joint power, and joint stiffness.
• To characterize the joint-level mechanical adaptations in response to combined changes in approach speed and distance.

Main Methods:

• Employed a 2 × 3 within-subjects design with 25 male university students performing ARJSL trials.
• Manipulated approach speeds (fast, slow) and approach distances (3, 6, 9 m).
• Utilized 3D motion capture synchronized with force platform data to quantify biomechanical variables including jump height, vertical touchdown velocity, reactive strength index, peak joint power (hip, knee, ankle), and joint stiffness.

Main Results:

• Significant interactions between approach speed and distance were found for jump height, vertical touchdown velocity, reactive strength index, and ankle stiffness.
• Approach strategy alterations systematically changed the distribution of mechanical power across the hip, knee, and ankle joints.
• Reactive strength index and ankle stiffness demonstrated particular sensitivity to combined speed and distance manipulations, indicating their role in stretch-shortening cycle intensity and joint loading.

Conclusions:

• ARJSL performance is contingent upon finely tuned, speed- and distance-specific biomechanical adaptations within the lower extremity.
• Approach speed and distance interact to influence power redistribution and stiffness behavior during the ARJSL.
• Findings provide a joint-level mechanical characterization of approach effects on ARJSL, emphasizing neuromechanical indicators of performance.