Researchers at the University of Alabama at Birmingham put 72 women, aged between 60 and 74, into three groups. The first group performed aerobic exercise once a week and resistance exercise also once a week, the second group did both aerobic and resistance exercises twice a week, while the last one was assigned three days of aerobic exercise and three days of resistance exercise a week.
After a period of four months, it was found that fitness gains did not differentiate significantly amongst the three groups. However, energy expenditure among the women exercising four times a week was higher than in any of the other two groups.
The women in the second group, who exercised four times a week, were burning around 225 additional calories a day in comparison to their energy expenditure at the beginning of the study. Those exercising twice a week were also burning nearly 100 more calories a day on top of their energy expenditure during exercise. However, the women exercising six times a week were found to be using nearly 200 less calories than they had been at the beginning.
The researchers suggested that the reason for the difference in energy expenditure could be due to the fact that the women exercising two or four times a week also began taking the stairs and walking for pleasure because of feeling energised, whilst the women exercising six times a week said that working out took too much of their time which they offset by driving or taking the elevator.