Effects of marathon training on maximal aerobic capacity and running economy in experienced marathon runners

Maximal aerobic capacity (VO_2max) and running economy (RE) are markers of running performance. A valid evaluation of RE may occur through allometric scaling of body mass (alloVO₂; ml kg^-0.66 min^-1), energy cost (EC; kcal kg^-1 km^-1), or percent of VO_2max (%VO_2max). Little is known about physiological changes that occur in competitive runners over a marathon training cycle. The VDOT score, incorporating VO_2max and RE, enables comparison of race performances under different temperature conditions. This study's purpose was to determine whether VO_2max and measures of RE change with marathon training, and to evaluate the relationship between these variables and VDOT. Eight runners (age 34±2 years; marathon <3:00 males, <3:30 females; five females) completed treadmill marathon-intensity-effort (MIE) and VO_2max tests at 10 and 1-2 weeks pre-marathon. Body composition (%BF) was determined using hydrostatic weighing. Paired t-tests were used to compare pre- and post-training values. The alpha level for significance was set at 0.05. Body fat decreased from 18.7±1.5% to 16.7±1.6%, VO_2max increased from 51.6±2.4 to 63.9±1.1 ml kg^-1 min^-1, and %VO_2max during the MIE decreased from 82.1±2.0 to 72.3±3.2% (p < 0.05 for all). VDOT was significantly associated with alloVO₂ (r = -0.779, p = 0.039) but not with VO_2max (r = 0.071, p = 0.867). Experienced competitive runners may increase VO_2max and decrease %BF after a marathon-specific training cycle. The decrease in %VO_2max in a MIE is likely due to a higher VO_2max, as other measures of RE did not change significantly. In this cohort, alloVO₂ was negatively correlated with race performance.