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.

Figure 1.docx (22 kB)
Figure 1

This document is currently not available here.