MATHEMATICAL CONSIDERATIONS FOR DERIVING THE CRITICAL LOAD FOR RESISTANCE EXERCISE

Authors

OK Anderson
PJ Succi
CC Voskuil
MT Byrd
HC Bergstrom
TK Dinyer-McNeely

Abstract

Olivia K. Anderson¹, Pasquale J. Succi², Caleb C. Voskuil³, M. Travis Byrd⁴, Haley C. Bergstrom², Taylor K. Dinyer-McNeely¹

¹Oklahoma State University, Stillwater, OK, ²University of Kentucky, Lexington, KY, ³Texas Christian University, Fort Worth, TX, ⁴Mayo Clinic, Scottsdale, AZ,

The critical load (CL) may reflect the highest sustainable load that can be completed for an extended number of repetitions. The performance of repetitions to failure at 4 submaximal loads is required to determine CL, which is defined as the slope of the total work (kg lifted x repetitions completed) vs. repetitions completed relationship (Figure 1). PURPOSE: This study examined the CL estimate derived from 2 trials (2T: 50%, 80% one-repetition maximum [1RM]), 3 trials (3₁T: 50%, 60%, 80% 1RM; 3₂T: 50%, 60%, 70% 1RM), and 4 trials (4T: 50%, 60%, 70%, 80% 1RM) to improve the efficiency of estimation. METHODS: 49 participants (mean ± SD: age 22 ± 3 yrs; height 173 ± 8 cm; body mass 68 ±15 kg) completed a 1RM for the leg extension and repetitions to failure at 50%, 60%, 70%, and 80% 1RM, on separate days. Repetitions completed and total work were recorded during each visit. A one-way repeated measures ANOVA and Pearson’s correlations were used to examine differences and relationships, respectively, among the 4 CL estimates. RESULTS: The one-way repeated measures ANOVA indicated the CL derived from 3₁T (18.2 ± 7.3 kg) was greater than 4T (17.8 ± 6.9 kg, p < 0.001), and 3₂T (12.6 ± 6.1 kg) was less than 4T (p < 0.001). There was no difference between the CL estimates derived from 2T (17.5 ± 7.1 kg) and 4T (p = 1.000). There were strong correlations between the CL estimates from 4T and 2T (r = 0.987, p < 0.001), and between 4T and 3₁T (r = 0.992, p < 0.001), and a moderate correlation between 4T and 3₂T (r = 0.545, p < 0.001). CONCLUSION: The strong correlation and lack of mean difference between the 4T and 2T CL derivations suggest completing fewer trials may provide accurate estimates of the CL. Reducing trials may be less fatiguing for the participant, as well as more time efficient for both the participant and the investigator. Further, CL estimates derived from 3₁T or 3₂T may over- or underestimate CL, respectively. Thus, careful consideration should be taken when determining the number of trials used to estimate the CL.

Recommended Citation

Anderson, OK; Succi, PJ; Voskuil, CC; Byrd, MT; Bergstrom, HC; and Dinyer-McNeely, TK (2022) "MATHEMATICAL CONSIDERATIONS FOR DERIVING THE CRITICAL LOAD FOR RESISTANCE EXERCISE," International Journal of Exercise Science: Conference Proceedings: Vol. 11: Iss. 9, Article 26.
Available at: https://digitalcommons.wku.edu/ijesab/vol11/iss9/26