Validity and Reliability of a 3-Point Load-Velocity Profile for Predicting Hex Bar Deadlift 1 Repetition Maximum

Area of Science:

• Sports Science
• Biomechanics
• Strength and Conditioning

Background:

• Assessing maximal strength (1RM) is crucial for training prescription.
• Traditional 1RM testing is time-consuming and can be fatiguing.
• Velocity-based training offers a potentially more efficient method for monitoring strength.

Purpose of the Study:

• To evaluate the between-session reliability of load-velocity parameters derived from a 3-point method in the hex bar deadlift.
• To determine the validity of a predictive 1RM model using these load-velocity parameters.
• To compare predicted 1RM with directly measured 1RM in resistance-trained individuals.

Main Methods:

• Nineteen resistance-trained subjects completed two testing sessions.
• Each session included a traditional 1RM test and a 3-load hex bar deadlift assessment for load-velocity profiling.
• Reliability was assessed using coefficient of variation (CV) and intraclass correlation coefficient (ICC).
• A linear mixed-effects model predicted 1RM from theoretical maximal load (L0) and theoretical maximum velocity (V0).

Main Results:

• Theoretical maximal load (L0) demonstrated excellent between-session reliability (CV = 5.2%, ICC = 0.97).
• Theoretical maximum velocity (V0) showed good reliability (CV = 6.0%, ICC = 0.70).
• The predictive model explained 97.5% of the variance in actual 1RM (marginal R² = 0.975).
• Predicted 1RM values were similar on average but had wide limits of agreement (±15.7 kg) compared to direct 1RM testing.

Conclusions:

• The 3-point load-velocity profile offers a reliable and valid method for predicting hex bar deadlift 1RM.
• This approach provides a less fatiguing and more efficient alternative for athlete strength monitoring.
• Individual variability necessitates caution; predicted 1RM should not be used interchangeably with direct 1RM testing.