Friday September 11 2015
Hopping may not be suitable for everyone
"Older people could reduce risk of osteoporosis by hopping for two minutes a day," the Daily Mirror reports. A UK study found regular hopping increased bone density in older men.
The study assigned more than 30 healthy older men to exercises on one leg and compared the change in bone density with the other leg.
It found five sets of 10 hops, with a 15-second rest between each set, every day increased the density of some parts of the hip. The men, aged 65 to 80 years old, were followed up with a second scan after 12 months.
Some of the media claim this has major implications for the prevention and management of osteoporosis. But these findings were from a group of healthy older males without osteoporosis and no other health conditions. It is unclear whether hopping would be effective, and safe, for people who actually have osteoporosis.
The follow-up time was also relatively modest – just 12 months – so it is uncertain whether this exercise regime would prevent bone fractures in the long term. Women feature in many of the newspaper pictures, but were not participants in this study.
Ways to prevent osteoporosis include weight-bearing exercises. For people aged over 60, this can include brisk walking. Read more about bone health.
Where did the story come from?
The study was carried out by researchers from Loughborough University, the University of Cambridge, University Hospitals Leicester, and Derby Hospitals NHS foundation Trust.
It was funded by the National Osteoporosis Innovative Award, a Medical Research Council UK Interdisciplinary Bridging Award, and a Loughborough University Scholarship.
The study was published in the peer-reviewed Journal of Bone and Mineral Research.
This study has been widely reported in the UK media, with many sources suggesting hopping reduces the risk of a fracture. This was not reported in the paper and it is not yet known whether the bone density improvements demonstrated led to reduced numbers of fractures.
What kind of research was this?
This randomised controlled trial aimed to evaluate the effects of these exercises on cortical and trabecular bone (found in the hip) and its 3D distribution across the hip.
This study design is the best way to assess such an effect, but as it was only the participants' legs that were randomised in this instance, both legs may have benefited from changes to other behaviours.
What did the research involve?
Researchers recruited 50 healthy men of European origin who were aged 65 to 80. The men had no involvement in exercises of a strength, power or weightlifting nature for more than one hour a week, and had no health conditions likely to influence bone, neuromuscular function or their ability to perform exercises.
The "exercise leg" of each participant was randomly assigned (left or right) using sealed opaque envelopes. Limb dominance had no effect on allocation.
All participants were to perform hopping exercises on their exercise leg only and avoid any other changes to their physical activity or dietary habits during the trial.
The hopping exercise involved around 10 minutes of activity and consisted of five sets of 10 hops, with a 15-second rest between each set. This was performed in a variety of directions. Exercises were to be performed as high and fast as they could on a hard, even surface, while barefoot and when another person was nearby.
Measurements of bone mineral content were taken by CT scan before and after the study period. This was performed by a radiographer who was unaware (blinded) to leg allocation and efforts were made to standardise leg placement. Researchers were interested in how the exercise affects different parts of the hip.
Participants were to complete a seven-day food diary and health and physical activity questionnaire before the trial began. Anthropometric measurements (height, weight and BMI) and body composition were taken by DEXA (DXA) scan before and after the trial period. The men were followed up after 12 months.
What were the basic results?
Of the 50 men who started the trial, only 34 remained for analysis. The withdrawal rate was 32% (16 men). This was mainly because of either health problems unrelated to the intervention, time commitments or discomfort during exercise.
The study found bone mineral density in the outer and spongy layers significantly increased over time in each leg. The density of the outer layer increased significantly more in the exercise leg, compared with the control leg.
There was a greater increase in density in the exercise leg than the control leg in terms of where the femur connects to the hip bone. Instability of the hip was reduced more in the exercise leg.
How did the researchers interpret the results?
The researchers state short bursts of regular hopping exercises increased hip bone density, and exercise that targets localised regions of the proximal femur (the section of bone that connects the upper thigh bone to the hip) could produce greater increases in bone strength and resistance to fracture.
This was a randomised controlled trial assessing the effect on hip bone density of hopping as a form of weight-bearing exercise in older men. The study found the hopping exercise to be of significant benefit to certain parts of the hip. But this study was performed in healthy men with no health concerns.
The study had a number of strengths and limitations. Strengths are that it was randomised in design, and the fact there was concealed allocation to the intervention group and blinded assessors, reducing the risk of bias. The researchers also performed calculations to estimate the number of participants needed for their study.
Limitations are that the study may have benefited from having a control group who did not take part in the hopping exercise, rather than just a randomly assigned leg. In addition, the sample size was quite small, the study did not assess physical activity or dietary habits after the intervention, and it was conducted in a group of healthy older men.
This means the findings may not be generalisable to other groups, especially those with osteoporosis, where boosting bone density would be of great benefit.
While this study has presented some significant findings, it is not possible to say whether this intervention would be of use to other older people who have health issues or are perhaps unsteady on their feet. The high drop-out rate of 32% suggests it may not be a suitable exercise for many men.
If you do have osteoporosis, hopping may not be the ideal exercise plan for you as there is a risk of falling, which could result in fracture. Your GP or the doctor in charge of your care should be able to recommend a suitable exercise plan.