From fitness magazine about benefits of jumping-kind of exercise:
You know high-impact exercise builds bone mass, but how much does it take for results?A recent study found that women who did an average of just one 60-minute high-intensity exercise session a week (running at a 7.5-minute-mile pace, jumping and aerobic stepping), as well as two 10-minute workouts (again high intensity), gained small but significant increase in thighbone density.Do your bones good and add sprints, jumping jacks, rope jumping, jumping with weights to your exercise plan two or three times a week for 10 – 15 minutes.