Force-velocity profiling in athletes: Reliability and agreement across methods.

Area of Science:

• Sports Science
• Biomechanics
• Human Movement Analysis

Background:

• Accurate assessment of individual force-velocity (FV) profiles is crucial for optimizing athletic performance.
• Previous research has explored various methods for FV profile assessment, but reliability and agreement across methods remain areas of concern.
• Understanding the test-retest reliability and inter-method agreement is essential for practical application in training and research.

Purpose of the Study:

• To evaluate the test-retest reliability and agreement between different measurement methods for individual lower limb force-velocity profiles in athletes.
• To compare the reliability of FV profile assessment across different exercises (squat jump, countermovement jump, leg press) and measurement techniques.
• To identify the most reliable FV variables and methods for practical use in sports science and coaching.

Main Methods:

• A multicenter study involving 27-82 male and female athletes tested twice before and after a 2-6 month training period.
• Individual FV profiles were determined using incremental loading protocols in squat jump (SJ), countermovement jump (CMJ), and leg press exercises.
• Force and velocity were measured using force plates, linear encoders, and flight time calculations, with linear regression used to extrapolate FV variables (F0, V0, Pmax, SFV).

Main Results:

• The slope of the FV profile (SFV) demonstrated poor reliability across all vertical jumping methods (CV: 14-30%, ICC: 0.36-0.79).
• The leg press exercise showed acceptable reliability for FV variables (CV: 3.7-8.3%, ICC: 0.82-0.98).
• Agreement across methods for F0 and Pmax was moderate to strong (Pearson r: 0.56-0.95), while agreement for V0 and SFV was weaker (r: -0.39-0.78).

Conclusions:

• The reliability of force-velocity variables derived from vertical jumping is poor, particularly for SFV and V0, irrespective of the measurement method.
• Leg press provides a more reliable method for assessing force-velocity characteristics compared to vertical jumps.
• Coaches and researchers should exercise caution when interpreting FV variables from vertical jumps and consider the limitations of different measurement techniques.