ABSTRACT.The study was conducted to investigate the specificity of training effects accruing from participation in programs of treadmill running and bicycle ergometer riding. Two groups of adult male subjects were pretested using PWC150tests on both the treadmill and bicycle ergometer and were found to be similar (P > .50) in their functional capacity as measured by both tests. For a period of six weeks one group engaged in treadmill running of increasing intensity while the other group participated in a progressive training program on a bicycle ergometer. The groups were subsequently post‐tested on both. The treadmill and bicycle ergometer tests indicated that the treadmill training group had improved significantly in physical working capacity as measured by both tests whereas the bicycle training group had improved significantly only as measured by the bicycle ergometer test. A 2‐way ANOVA for repeated measures was employed to test for suspected interaction between training tasks and PWC150tests. The results identified the existence of significant interaction between the bicycle training program and the bicycle PWC150test. It was concluded that training effects of cycling are more specific than those of running and, therefore the choice of a work capacity test for assessing changes in circulorespiratory functional capacity resulting from exercise is critical.