For strong bones you need to do fitness training at least twice a week
The over-fifties who want to keep their bones strong by doing fitness training need to make sure they train at least twice a week. And more often is better, write researchers at the University of Erlangen, Germany in the Scandinavian Journal of Medicine and Science in Sports. The Germans followed a group of women for over twelve years who did fitness training under supervision.
The researchers gathered their data for the Erlangen Fitness and Osteoporosis Prevention Study, in which 41 women were monitored from 1998 to 2010. At the start of the study the women were aged between 48 and 60 and trained 4 times a week or less [EG]. The researchers compared this group with a control group of 44 comparable women who did no training [CG].
The women did a maximum of two group-training sessions a week in a gym supervised by a trainer. Each workout lasted an hour, and consisted of just under half an hour of cardio training and just over half an hour of strength training.
The strength training consisted of a dozen basic exercises for the large muscle groups, and was periodised: for three months the women trained using weights with which they could do 12-14 reps, then they did six weeks at a weight with which they could do 20-25 reps.
The women trained at home doing skipping, stretches and exercises with an elastic resistance band. They were given a new training scheme every three months.
The researchers discovered that the women did not all train with the same frequency, so they divided the women in the experimental group into two subgroups: a high-frequency exercise group [HEF-EG], which trained on average 2.5 times per week, and a low-frequency exercise group [LEF-EG], which trained on average 1.5 times a week.
After twelve years the low-frequency trainers had lost as much bone mass as the women in the control group, as the first table below shows. Click on it for the complete version.
The frequent trainers were better off, as the table above shows. The table compares the women who had done a relatively high amount of training with the women who had trained relatively little. Click on it for the complete version. The bone density in the spine had increased by a small amount in the frequent trainers, and the exercise programme they followed also seemed to delay the loss of bone mass in the hips.
"Although our findings might not be generalizable across all exercise types and cohorts, the take home message of the present article may be that even if exercise is applied with high intensity/impact and is regularly adapted and consequently supervised, it is crucial to realize an overall exercise frequency of at least 2 sessions/week to impact bone mass density", the Germans summarise.
Scand J Med Sci Sports. 2014 Jun;24(3):526-34.
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