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Resistance Training/Periodization

(9) VALDIITY OF ESTIMATING MAXIMUM MUSCULAR STRENGTH IN THE BACK SQUAT USING SUBMAXIMAL BAR VELOCITY: A SYSTEMATIC REVIEW AND META-ANALYSIS

Thursday, July 13, 2023
1:00 PM – 1:15 PM East Coast USA Time
Location: Milano I-II
Abstract Details: One repetition maximum (1RM) testing is the gold standard for assessing maximum strength in resistance training exercises. However, 1RM testing can be time consuming and physically taxing on the body and may be difficult to perform in team-settings with practice and competition schedules. As an alternative, 1RM can be estimated from bar or movement velocity at submaximal loads based on the load-velocity relationship. Despite its potential utility, the validity of this method has yielded inconsistent results.

Purpose: The purpose of this systematic review and meta-analysis is to quantify the observed error when using bar velocity to estimate 1RM in the free weight back squat exercise and identify potential sources of heterogeneity and that may contribute additional error.

Methods: A systematic search of Web of Science, Pubmed, and SPORTDiscus electronic databases was conducted using combinations of the following keywords “velocity-based training,” “load-velocity profiling,” “mean velocity,” “mean propulsive velocity,” “peak velocity,” “maximal strength,” “1RM,” “estimation,” “prediction,” “back squat,” and “regression”. Initial systematic database search identified 372 unique articles with only 5 articles remaining after removing studies that did not meet inclusion criteria. Statistical analyses were performed using the “metafor” package in R (v 4.2.1; R Core Team, https://www.r-project.org/).

Results: A total of 27 effects were analyzed; 85.2% of effects were obtained from male participants only, while the remaining 14.8% came from female participants. The effects included data from 71 participants, aged 17.8-25.4 years ([mean ± SD] 22.8 ± 2.9 yrs.). Measured 1RMs ranged from 86.5-153.1 kg (131.8 ± 26.9 kg), whereas estimated 1RMs ranged from 88.6-171.6 kg (148.0 ± 28.6 kg). The number of submaximal loads used to estimate 1RM ranged from 2-8 submaximal loads (4.5 ± 2.6 loads). Using a 3-level intercept only model, the 27 effects indicated that free weight back squat 1RM is overestimated when derived from bar velocity when using the minimal velocity threshold method (ES=0.5304, 95% CI: 0.1878 to 0.8730, p=0.0038) with high heterogeneity in the observed error between measured and estimated 1RM (I2= 91%). Potential moderating variables that were established a priori include the number of submaximal loads(β=-0.0225, p=0.3836), highest submaximal load (β=-0.0129, p=0.1224), and participant height (β=-0.0638, p=0.6120); none of these moderators were independently associated with the observed error in estimating 1RM.

Conclusions: Based on the effect size calculated using the 3-level intercept model, overestimations of 1RM in terms of kilograms could range from 3.35-20.05kg. The consistent overestimation of 1RM and high levels of heterogeneity when using the MVT method indicates that the MVT method is not a viable option for estimating 1RM in the free weight back squat. PRACTICAL APPLICATION: Strength and conditioning professionals should exercise caution when estimating 1RM from the load-velocity relationship. Alternatively, researchers should aim to develop better estimation methods for using the load velocity relationship to estimate 1RM in the free weight back squat exercise.

Acknowledgements: None.