How much exercise should we take
Exercise benefits us in an enormous number of ways – from helping control weight to reducing the risk of heart disease and osteoporosis. Different benefits almost certainly demand different exercise doses
The current NHS Guideline, from which I quote freely below, recommends a mix of aerobic exercise and muscle strengthening.
“To stay healthy, adults aged 19-64 should try to be active daily and should do:
- At least 150 minutes (2 hours and 30 minutes) of moderate intensity aerobic activity such as cycling or fast walking every week or
- 75 minutes (1 hour and 15 minutes) of vigorous intensity aerobic activity such as running or a game of singles tennis every week, and
- muscle-strengthening activities on 2 or more days a week that work all major muscle groups (legs, hips, back, abdomen, chest, shoulders and arms).
A rule of thumb is that 1 minute of vigorous-intensity activity is about the same as 2 minutes of moderate-intensity activity.
One way to do your recommended 150 minutes of weekly physical activity is to do 30 minutes on 5 days a week.”
“Examples of activities that require moderate effort for most people include:
- walking fast
- water aerobics
- riding a bike on level ground or with few hills
- doubles tennis
- pushing a lawn mower
Moderate-intensity activity will raise your heart rate and make you breathe faster and feel warmer. One way to tell if you’re working at a moderate intensity is if you can still talk, but you can’t sing the words to a song.
Examples of activities that require vigorous effort for most people include:
- jogging or running
- swimming fast
- riding a bike fast or on hills
- singles tennis
- skipping rope
- martial arts
Vigorous-intensity activity means you’re breathing hard and fast, and your heart rate has gone up quite a bit. If you’re working at this level, you won’t be able to say more than a few words without pausing for a breath.
In general, 75 minutes of vigorous-intensity activity can give similar health benefits to 150 minutes of moderate-intensity activity.
What counts as muscle-strengthening activity?
Muscle strength is necessary for daily activities, to build and maintain strong bones, to regulate blood sugar and blood pressure and to help maintain a healthy weight.
Muscle-strengthening exercises are counted in repetitions and sets. A repetition is 1 complete movement of an activity, like lifting a weight or doing a sit-up. A set is a group of repetitions.
For each activity, try to do 8 to 12 repetitions in each set. Try to do at least 1 set of each muscle-strengthening activity. You’ll get even more benefits if you do 2 or 3 sets.”
How good are these recommendations?
They are both realistic and highly beneficial. They are certainly enough to bring appreciable increase in physical fitness together with health and longevity benefits. Note, however, that the NHS Guidelines do point out that there is substantial evidence that more vigorous-intensity activity can bring health benefits over and above that of moderate intensity activity.
Almost identical recommended exercise guidelines have been produced by a number of countries and continental groups. There is no science to these recommendations which are a compromise between what is ideal and what is achievable. The recommended level has been plucked from the sky and has no real evidence to support it. The benefits of exercise increase with increasing exercise level – but the more exercise that is recommended the smaller the chance of it being taken up. No one has yet demonstrated the cross-over point beyond which the benefit of exercise at a population level is cancelled out by the reduction in uptake! In 2018 the “Physical activity guidelines for health and prosperity in the United States” were published. The overall levels of recommended activity were not changed from previous guidelines but the way in which the exercise is broken up was changed. “Even short-duration activity lasting less than 10 minutes is beneficial.”
The effect of age
As we get older the benefits of exercise get greater and greater but we take less and less of it. In the US the average walking time for 20-29 year olds is about 30 minutes per day which has fallen to about nine minutes per day by the age of 70-79. Very reasonably it is argued that it is futile to advise the elderly to triple their exercise – they just won’t do it. The target for everyone should not be a fixed amount of exercise but an increase which is within the bounds of possible attainment.
Doing a little is much better than nothing
The graph below shows the return for effort expended. For most health problems, including premature mortality, the greatest difference is seen between the inactive and the slightly active. Just doing a bit is a help. Of course the more you do the greater the benefits but don’t let that put you off doing something.
The dangers of admission to hospital
When older people are admitted to hospital they are faced by a hazard other than the reason for their admission.
When in hospital older patients spend most of their time in bed, even if they are able to walk independently and most do not walk at all. Consequently, hospital associated disability is prevalent, affecting more than one third of older adults admitted to hospital. It has been said that 10 days in a hospital bed leads to 10 years’ worth of lost muscle mass in people over age 80.
Hospital associated disability—defined as loss of ability to perform one or more basic activities of daily living such as using the toilet, bathing, dressing, transferring from bed to chair, or walking independently at discharge—is associated with long term disability, institutionalisation and death. Simple exercises can help prevent it, according to one recent trial which reported a 64% reduction in hospital associated disability among older adults (mean age 88) who were supervised doing simple exercises such as walking and rising from a chair for about 20 minutes a day.
So if you are visiting an elderly person person in hospital you could really help by taking short walks around the ward with them Sadly this will not always be welcomed by the nursing staff.