The purpose was to investigate the effects of simultaneous endurance and strength training repeatedly performed in the same training sessions (hybrid training). Twenty-six habitually active female physical-education students took part in the study. They were assigned to a hybrid training group (HT) or one of two control groups (CON1; only endurance training and CON2; maintained their normal training regimen). In a pre- and post-test training design all the subjects were tested before and after the intervention period concerning peak oxygen uptake while pedalling on a cycle ergometer and power output in a progressive cycle ergometer pedalling power/strength test. The HT intervention group and the CON1 group trained three times per week for five weeks, while the CON2 group did not change their normal training regimen. The HT group used a pre-programmed cycle ergometer to pedal at a mean oxygen uptake of 70-75% VO2peak for 30 minutes, but the training time was divided into 60 intermittent work periods (6 seconds) at a very high relative intensity (approximately 190 % of VO2peak) interspersed with low-intensity work periods (24 seconds) at about 45% of VO2peak. The CON1 group trained at the same mean oxygen uptake level as the HT group but during 30 minutes continuous training. The HT group significantly increased VO2peak and muscle power performance. The CON1 group increased VO2peak significantly but not power/strength. The CON2 group did not change significantly in the parameters studied. Thus, it can be concluded that in-session hybrid training allows simultaneous significant improvements of both VO2peak and muscle power performance during cycle ergometer pedalling.