Although the original (ORG) physical working capacity at fatigue threshold (PWCFT) assessment has demonstrated strong reliability and sensitivity to training and/or nutritional interventions, limitations may exist regarding the method of PWCFT estimation. However, a relatively new mathematical method, called Dmax, has been shown to be objective and reliable when estimating metabolic and neuromuscular fatigue thresholds. To date, however, no study has examined whether the Dmax method for estimating the work rate at PWCFT is similar to the ORG method. PURPOSE: The purpose of this study is to evaluate the reliability and validity of the Dmax-EMG method for estimating and tracking changes in PWCFT. METHODS: In the reproducibility study, 11 men (age: 21.9 ± 1.37 years; height: 175.6 ± 8.65 cm; body mass: 82.1 ± 13.92 kg) completed two incremental exercise tests (GXT) to exhaustion on nonconsecutive days. In the validity study, 11 active men (age: 23.4 ± 3.0 years; height: 177.9 ± 7.8 cm; body mass: 80.9 ± 10.7 kg) and 10 active women (age: 22.3 ± 3.1 years; height: 166.6 ± 9.5 cm; body mass: 62.8 ± 8.7 kg) volunteered to perform 12 sessions of high-intensity interval training (HIIT) over 4-weeks along with a pre- and post-training GXT to compare the Dmax to the ORG method of estimating PWCFT. RESULTS: The reproducibility study revealed no significant differences between the first (181.5 ± 29.2 W) and second (181.9 ± 26.18 W) GXT trials (p = 0.87). In addition, ICC3,1 resulted in 0.949 with an SEM of 6.28 W and a MD of 17.41 W. In the crossvalidation, the CE between actual and predicted PWCFT was not statistically different at pre (-6.7 W; p > 0.05) or post (-7.2 W; p > 0.05). Pre (r = 0.87) and post (r = 0.84) validity coefficients were considered very strong and the pre and post TE PWCFT values were 30.8 W and 32.5 W, respectively. Wide limits of agreement were calculated in the Bland-Altman analyses (pre: -68.36 to 54.93 W; post: -57.77 to 72.06 W) with no significant biases in both pre (-6.7 ± 30.8 W; p = 0.330) and post (-7.2 ± 32.5 W; p = 0.325). In addition, 95.2% and 100% participants fell within ±1.96 standard deviations of the mean difference for pre and post, respectively. CONCLUSION: Results of the study suggest that the Dmax method is both a reproducible and a valid method to estimate PWCFT when compared to the ORG method in young men.


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Graduation Date





Stout, Jeffrey


Master of Science (M.S.)


College of Education and Human Performance


Educational and Human Sciences

Degree Program

Sport & Exercise Science; Applied Exercise Physiology









Release Date

May 2016

Length of Campus-only Access


Access Status

Masters Thesis (Open Access)