New research from the University of Exeter and the University of Leicester, both in the United Kingdom, suggests that a single 1-minute bout of high-intensity, weight-bearing physical activity is associated with better bone health in women.
Such brief bursts of activity are equivalent to a run at a medium pace for premenopausal women, and a slow-paced jog for postmenopausal women. The findings were published in the International Journal of Epidemiology.
Osteoporosis is a bone disease that causes bone to become weak and brittle. Bone tissue is constantly broken down and replaced, but osteoporosis occurs when new bone production does not keep pace with the removal of old bone.
Individuals with osteoporosis have holes and spaces in the bone that are larger than those of healthy bone. This reduced bone density and mass make the bones more likely to break.
According to the National Osteoporosis Foundation, there are around 54 million people in the United States living with osteoporosis and low bone mass. Studies estimate that 1 in 2 women and 1 in 4 men aged 50 years and older may break a bone as a result of osteoporosis.
The likelihood of developing osteoporosis significantly increases for women who have experienced menopause. Therefore, finding strategies that may optimize bone health in premenopausal and postmenopausal women is a priority.
Evidence shows that being inactive is a modifiable risk factor for osteoporosis. But how physical activity helps to maintain or minimize the loss of bone mass is not understood as well as other modifiable risk factors, such as diet, smoking, and alcohol.
The 2008 Physical Activity Guidelines for Americans recommend at least
The new research examined whether or not physical activity relevant to bone health was associated with healthy bone in premenopausal and postmenopausal women.
'Clear link' between exercise, bone health
Using data from UK Biobank on more than 2,500 women, lead author Dr. Victoria Stiles, a senior lecturer in Sport and Health Sciences at the University of Exeter, and team compared activity levels as measured by monitors worn on the wrist for a week, with bone health as measured by an ultrasound scan on the participants' heel bones.
Analysis by the researchers showed that women who participated in between 60 and 120 seconds of high-intensity, weight-bearing physical activity each day had 4 percent better bone health than women who took part in under a minute of physical activity. Furthermore, women who did more than 2 minutes of this type of exercise had 6 percent better bone health.
"We don't yet know whether it's better to accumulate this small amount of exercise in bits throughout each day or all at once, and also whether a slightly longer bout of exercise on 1 or 2 days per week is just as good as 1-2 minutes a day," says Dr. Stiles.
"But there's a clear link between this kind of high-intensity, weight-bearing exercise and better bone health in women."
Dr. Stiles notes that due to the study being cross-sectional - that is, an observational study that analyzes data from a population at a particular time point - they cannot be certain whether the high-intensity physical exercise led to better bone health or whether individuals with better bone health tend to do more of this exercise type.
"However, it seems likely that just 1-2 minutes of running a day is good for bone health," she adds.
Dr. Stiles and colleagues broke the UK Biobank data into single-second segments to observe how individuals go about their daily tasks.
"We wanted to make every second count in our analysis, because short snippets of high-intensity activity are more beneficial to bone health than longer, continuous periods. We were careful not to ignore short bursts of activity throughout the day."
Dr. Victoria Stiles
Having healthy bones has many associated benefits, including a decreased risk of developing osteoporosis and experiencing fewer fractures in older age.