Validity of an Alternative Method for Estimating Anaerobic Contribution During Running in Normoxia and Hypoxia

Authors

Ethan J. Hein, University of North Texas, DentonFollow
Sarah E. Deemer, University of North Texas, DentonFollow
Lydia K. Caldwell, University of Dayton, OhioFollow
Austin B. Shaw, University of North Texas, DentonFollow
Brady C. McLain, University of North Texas, DentonFollow
Jacob L. McNary, University of North Texas, DentonFollow
Claudio A. Gobatto, University of Campinas, Limeira, São Paulo, BrazilFollow
Marcelo Papoti, University of São Paulo, School of Physical Education and Sports, Ribeirão Preto, BrazilFollow
Fúlvia de Barros Machado-Gobatto, University of Campinas, Limeira, São Paulo, BrazilFollow
David W. Hill, University of North Texas, DentonFollow

Abstract

Anaerobic metabolism is vital for sustaining work rates during severe-intensity exercise, particularly under environmental conditions such as hypoxia where aerobic metabolism is constrained. Accumulated oxygen deficit (AOD) is the gold-standard method for quantifying anaerobic contribution, yet its implementation is limited by extensive laboratory testing. An alternative approach (AOD_alt) estimates anaerobic contribution from a single exercise bout and provides insight into the distinct contributions of phosphocreatine and glycolysis. However, its validity during running under conditions of reduced oxygen availability remains unexplored. PURPOSE: To determine the validity of AOD_alt during severe-intensity treadmill running in normoxia and hypoxia. METHODS: Twenty-three adults (10W/13M; age 32 ± 7 y; VO_2max 54 ± 6 mL∙kg^-1∙min^-1) completed incremental and constant-speed treadmill running tests in normoxia (F_IO₂ = 21%) and hypoxia (F_IO₂ = 15%). An incremental test was used to determine VO_2max, oxygen demand, and a running speed for the subsequent tests. Two severe-intensity, constant-speed tests were performed at identical speeds across conditions of F_IO₂. AOD was calculated as the difference between estimated oxygen demand and accumulated oxygen uptake; AOD_alt was calculated as the sum of the phosphocreatine and glycolytic contributions derived from post-exercise VO₂ recovery kinetics and blood lactate concentration, respectively. A two-way repeated-measures ANOVA (method x condition) and Pearson correlations were used for analyses. RESULTS: There was no method x condition interaction (p = 0.36) and no main effect of method (p = 0.74). Anaerobic contribution was greater in hypoxia than normoxia (main effect of condition, p < 0.001). In normoxia, AOD (49.4 ± 10.7 mL∙kg^-1 O₂) and AOD_alt (51.0 ± 11.2 mL∙kg^-1 O₂) were similar and strongly correlated (r = 0.68). In hypoxia, AOD (70.8 ± 12.2 mL·kg^-1 O₂) and AOD_alt (70.5 ± 17.6 mL∙kg^-1 O₂) were also similar and correlated (r = 0.67). CONCLUSION: Reduced oxygen availability increased anaerobic contribution without compromising AOD_alt estimates during severe-intensity running. These findings support AOD_alt as a valid measure of anaerobic contribution under hypoxic conditions and highlight its utility for coaches and athletes training at altitude who may have limited time for testing sessions.

Recommended Citation

Hein, Ethan J.; Deemer, Sarah E.; Caldwell, Lydia K.; Shaw, Austin B.; McLain, Brady C.; McNary, Jacob L.; Gobatto, Claudio A.; Papoti, Marcelo; de Barros Machado-Gobatto, Fúlvia; and Hill, David W. (2026) "Validity of an Alternative Method for Estimating Anaerobic Contribution During Running in Normoxia and Hypoxia," International Journal of Exercise Science: Conference Proceedings: Vol. 2: Iss. 18, Article 61.
Available at: https://digitalcommons.wku.edu/ijesab/vol2/iss18/61