Velocity Loss Is Not an Accurate Predictor of the Percentage of Completed Repetitions During the Prone Bench Pull Exercise

Abstract

Pérez-Castilla, A, Miras-Moreno, S, Janicijevic, D, and García-Ramos, A. Velocity loss is not an accurate predictor of the percentage of completed repetitions during the prone bench pull exercise. J Strength Cond Res 37(5): 1001–1008, 2023—The primary aim of this study was to explore the goodness of fit and accuracy of both general and individual relationships between the magnitude of velocity loss (%VL) and the percentage of performed repetitions with respect to the maximal number of repetitions that can be completed to failure (%Rep) during the Smith machine prone bench pull exercise. Fifteen male sports science students completed a preliminary session to determine the bench pull one-repetition maximum (1RM) and 2 identical experimental sessions separated by 48–72 hours. In each experimental session, subjects randomly performed single sets of repetitions to failure separated by 10 minutes against the 60% 1RM, 70% 1RM, and 80% 1RM during the Smith machine bench pull exercise. Individual %Rep-%VL relationships presented a greater goodness of fit than general %Rep-%VL relationships at the 60% 1RM (R2 = 0.85–0.97 vs. 0.79–0.85), 70% 1RM (R2 = 0.84–0.99 vs. 0.77–0.84), and 80% 1RM (R2 = 0.84–1.00 vs. 0.74–0.80). However, the accuracy (absolute errors) in estimating the %Rep during the second testing session based on the %Rep-%VL equations obtained in the first testing session did not differ between the individual and general %Rep-%VL equations in 8 of 9 comparisons (p ≥ 0.102). The absolute errors between the actual and predicted %REP were unacceptable (>10%) in 11 of 18 comparisons, and acceptable (5–10%) in 7 of 18 comparisons. These results highlight that the %Rep cannot be estimated with high degree of accuracy from VL recordings during the Smith machine bench pull exercise, regardless of whether individual or general Rep-%VL relationships are considered.

Inter-repetition Rest Impact on Percentage of Repetition Completed at Certain Velocity Loss

“…Our findings are in line with previous studies that reported a moderate to strong goodness-of-fit for the general %rep-%VLT relationships obtained in several resistance training exercises ( R 2 ≥ 0.77) 6 7 10 11 12 13 26 . In addition, supporting our third hypothesis, the individual %rep-%VLT relationship provided a higher goodness-of-fit than the general %rep-%VLT relationship.…”

“…In addition, supporting our third hypothesis, the individual %rep-%VLT relationship provided a higher goodness-of-fit than the general %rep-%VLT relationship. These results are in agreement with those demonstrated for the Smith machine bench press ( R 2 =0.97–0.99 vs. 0.80–0.94) 11 , Smith machine prone bench pull ( R 2 =0.84–1.00 vs. 0.74–0.85) 10 , and free-weight back squat ( R 2 =0.24–1.00 vs. 0.67–0.80) 14 exercises. For the reason explained above, these results are likely due to the high variability that exists across individuals in the pattern of repetition velocity decline during the training set.…”

“…It has also been shown that individual %rep-%VLT relationships provide a better goodness-of-fit and errors than general %rep-%VLT relationships during the Smith machine bench press and prone bench pull exercises 10 11 . However, other authors have recently observed a high inter-individual variability (between-subject CV=10.7–34.3%) for %rep associated with different VLTs 10 12 13 and, more surprisingly, an unacceptable accuracy (absolute errors>10%) when the individual and general %rep-%VLT equations were used to estimate the %rep in a subsequent session 10 14 . These divergent findings highlight the need for future research to draw more robust conclusions.…”

Relationship Between the Number of Repetitions in Reserve and Lifting Velocity During the Prone Bench Pull Exercise: An Alternative Approach to Control Proximity-to-Failure

“…These results are in agreement with previous findings by Mor án-Navarro et al (17) who observed a narrow range for the absolute velocity thresholds corresponding to 2 (0.50-0.53 m•s 21 ), 4 (0.56-0.58 m•s 21 ), 6 (0.62-0.64 m•s 21 ), and 8 (0.67-0.69 m•s 2 1 ) RIR when all loading magnitudes were taken together (65, 75, and 85% 1RM) during the Smith machine prone bench pull exercise. The comparable accuracy could be explained because general RIR-velocity equations are affected by the high interindividual variability in the number of repetitions completed when reaching a given magnitude of velocity loss (7,21,22), while individual RIR-velocity relationships are more affected when the velocity decline from repetition-to-repetition moves away from linearity (7). In addition, the greater absolute errors for $2 RIR could be explained by the greater intraindividual and interindividual variability for repetition velocities far from momentary failure (6).…”

“…This study is part of a larger project investigating the feasibility of different velocity-based methods to control the proximity-tofailure during the Smith machine prone bench pull exercise. The results regarding the %Rep-%VL and RTF-velocity relationships have been published elsewhere (16,22), while in this study, we examined the possibility of estimating the RIR from velocity recordings. More specifically, to shed light on the importance of individualizing the RIR-velocity relationships, these relationships were constructed pooling the data from all subjects recruited for this study (general RIR-velocity relationship) as well as independently for each subject (individual RIR-velocity relationship).…”