Well, that excuse is no longer valid, according to researchers at the University of Wisconsin—Oshkosh. They believe that shorter, cumulative cardio sessions may be just as effective as one longer bout when it comes to fitness gains and fat loss.

They recruited a study group of overweight female college students (they had a body mass index of 28 or above), who were then randomly placed into one of three exercise groups or a diet-only control group. The exercising groups trained at 75% of heart rate reserve 3—5 days a week in either three 10-minute bouts of exercise per day (3x10), two 15-minute bouts per day (2x15) or one 30-minute bout per day (1x30).  Subjects were tested pre- and post-treatment for aerobic fitness, bodyweight, skin fold thickness and circumference measures. Each was asked to follow a self-monitored calorie-restricted diet (80% of predetermined resting metabolic rate) for the 12-week duration of the study.

In all three exercising groups, V02 max increased, while eight, body mass index, sum of skin folds and sum of circumferences decreased following the exercise program.

Thus, the researchers concluded that several shorter bouts of exercise have similar effect to one continuous bout with regard to aerobic fitness and weight loss during caloric restriction in overweight young women. We’re willing to bet, however, that this strategy will work for anyone. If you opt to do cardio after your resistance training workout, you could break it up into several shorter bouts and avoid that long, boring aerobic stint at the end of your workout (which you often skip anyway!).

*Journal of the American College of Nutrition