Anaerobic Capacity in Running: The Effect of Computational Method

To date, no study has compared anaerobic capacity (AnC) estimates computed with the maximal accumulated oxygen deficit (MAOD) method and the gross energy cost (GEC) method applied to treadmill running exercise.

Four different models for estimating anaerobic energy supply during treadmill running exercise were compared.

Fifteen endurance-trained recreational athletes performed, after a 10-min warm-up, five 4-min stages at ∼55-80% of peak oxygen uptake, and a 4-min time trial (TT). Two linear speed-metabolic rate (MR) regression models were used to estimate the instantaneous required MR during the TT (MR ), either including (5+Y ) or excluding (5-Y ) a measured Y-intercept. Also, the average GEC (GEC ) based on all five submaximal stages, or the GEC based on the last submaximal stage (GEC ), were used as models to estimate the instantaneous MR . The AnC was computed as the difference between the MR and the aerobic MR integrated over time.

The GEC remained constant at ∼4.39 ± 0.29 J⋅kg^-1⋅m^-1 across the five submaximal stages and the TT was performed at a speed of 4.7 ± 0.4 m⋅s^-1. Compared with the 5-Y , GEC , and GEC models, the 5+Y model generated a MR that was ∼3.9% lower, with corresponding anaerobic capacities from the four models of 0.72 ± 0.20, 0.74 ± 0.16, 0.74 ± 0.15, and 0.54 ± 0.14 kJ⋅kg^-1, respectively (F _1.07,42 = 13.9, P = 0.002). The GEC values associated with the TT were 4.22 ± 0.27 and 4.37 ± 0.30 J⋅kg^-1⋅m^-1 for 5+Y and 5-Y , respectively (calculated from the regression equation), and 4.39 ± 0.28 and 4.38 ± 0.27 J⋅kg^-1⋅m^-1 for GEC and GEC , respectively (F _1.08,42 = 14.6, P < 0.001). The absolute typical errors in AnC ranged between 0.03 and 0.16 kJ⋅kg^-1 for the six pair-wise comparisons and the overall standard error of measurement (SEM) was 0.16 kJ⋅kg^-1.

These findings demonstrate a generally high disagreement in estimated anaerobic capacities between models and show that the inclusion of a measured Y-intercept in the linear regression (i.e., 5+Y ) is likely to underestimate the MR and the GEC associated with the TT, and hence the AnC during maximal 4-min treadmill running.