The Effect of Weightlifting Belt on the Relative Load-Velocity Relationship and One-Repetition Maximum Prediction Accuracy in the Free-Weight Back Squat

Huang, Y, García-Ramos, A, Chen, Z, Li, Z, Yu, J, Geng, Y, Li, D, Jia, B, and LAM, W-K. The effect of weightlifting belt on the relative load–velocity relationship and one-repetition maximum prediction accuracy in the free-weight back squat. J Strength Cond Res XX(X): 000–000, 2026—This study compared the relative load-velocity relationship between free-weight back squats performed with (SWB) and without (SNB) wearing a weightlifting belt, and examined the accuracy of the absolute load–velocity relationship to estimate SWB one-repetition maximum (1RM). Twenty-five resistance-trained athletes (14 men and 11 women) completed 2 sessions in both SWB and SNB conditions. The load–velocity relationship, modeled using both multiple-point (40, 55, 70, and 85% 1RM) and 2-point (40%, 85% 1RM) methods, was used to estimate SWB 1RM of the second session based on individual and average optimal minimum velocity thresholds from the first session. SWB significantly increased 1RM (119.2 ± 36.8 vs. 114.0 ± 34.9 kg; p < 0.001) and bar velocities across all 4 submaximal absolute loads (p = 0.006–0.026), but slightly reduced velocities at relative loads of 85–100% 1RM (p = 0.025–0.049). The velocities corresponding to different %1RM demonstrated acceptable reproducibility (mean coefficient of variation = 5.2%, mean intraclass correlation coefficient = 0.85) and no significant differences between the multiple- and 2-point methods (p = 0.111–0.944). All approaches estimated SWB 1RM with low to moderate absolute percentage errors (4.2–5.2%). In conclusion, using a weightlifting belt does not substantially affect the %1RM–V relationship below 85%1RM and yields 1RM estimations with accuracy comparable with that previously reported for the SNB condition. The 2-point method combined with an optimal minimum velocity threshold provides a time-efficient approach for estimating 1RM and establishing the associated %1RM–V relationship in the free-weight back squat.