Gross efficiency responses to exercise conditioning in adult males of various ages

Abstract

This study investigated gross efficiency changes in a group of 60 adult males (mean age 39.2 ± 1.2 years) resulting from endurance training and age‐related responses to such training in sub‐groups (each n = 20) of younger (30.7 ± 0.7 years), intermediate (38.3 ± 0.5 years) and older (48.6 ± 1.1 years) subjects. Gross efficiency (%) was calculated from work output, oxygen consumption and RER energy equivalents following 10 min standard cycle ergometry exercise at 100 W and 50 rev min^‐1. Measurements were made at pre‐, mid‐ and post‐8 months of training, which involved progressive walking/jogging activities designed to enhance endurance capacity. In the total group, VO ₂ decreased pre‐ to post‐training from 2.15 ± 0.02 to 1.93 ± 0.01 1 min^‐1 (P < 0.01). In the sub‐groups, both the younger and older subjects showed a significantly reduced VO ₂ , from 2.17 ± 0.01 to 1.98 ± 0.04 1 min^‐1 and 2.05 ± 0.08 to 1.86 ± 0.03 1 min^‐1 respectively (P < 0.05), but no significant changes were noted at mid‐training. In the intermediate age subjects, while there were trends towards a reduced VO ₂, none was significant. The ANOVA revealed increased mean gross efficiency in the total group from pre‐(14.3 ± 0.1%) to post‐ (15.5 ± 0.2%) (P < 0.05) but not at mid‐training (14.8 ± 0.2%). While similar trends were observed in the sub‐groups, gross efficiency increases were not significant, although changes in gross efficiency were reflected in VO ₂. The findings suggest that during standardized exercise, oxygen cost may be reduced and gross efficiency increased in adult males following endurance training and that such changes may take place over a variety of age ranges.