Strength
 
Strength is one of the four aspects of physical fitness together with suppleness, skill and stamina.  Strength is provided by the  muscles and is measured by the ability to move weights, including, of course, the weight of the human body.   The term ‘power’ is often used too and power means strength at speed.   For example, does a person have the strength to get up from a chair is one question.  The question related to power is to ask how quickly they can get up from the chair and how many times can they do it within a minute?  That is power.  The term ‘sarcopenia’ is sometimes used by doctors but this just means ‘weak muscles’ in Greek and is not a disease like Parkinson’s disease or stroke.   In fact for all of us our muscles are getting weaker unless we take action and it is useful to consider how the four processes affect us as we live longer impact on strength and power.
 
Ageing
 
There is some loss of muscular strength due to ageing but if you look at people who have kept their muscles strong their performance is remarkable even in their seventies, eighties and nineties.  The other factors are more important.
 
Loss of fitness
 
Loss of fitness is probably the single most important cause of muscle weakness and loss of power, and by this we do not mean not going to a gym, although going to a gym is helpful at any age, but the loss of muscular strength that comes about as a result of modern lifestyle in a world dominated by the car, the computer and the desk job.   Although no one would wish to go back to a world in which all roads had to be dug by shovels and all clothes washed by hand, we are now living in an environment in which muscular strength is lost from the early twenties on, sometimes complicated by disease.
 
Disease
 
There are some diseases that affect muscles directly but any disease that causes immobility or reduced movement of a joint and the muscles that move it will lead to accelerated loss of muscle strength.   People who are lucky enough to get to a rehabilitation service after the onset of disease will get appropriate advice from a physiotherapist but most people with long-term health problems will not get this type of expert advice.  Arthritis UK, the main charity promoting research in arthritis, has, however, done great work in promoting the benefits of activity for people with arthritis.
 
This is now being recognised and the British Geriatric Society led by Professor Amit Arora has successfully introduced the concept of Deconditioning, the loss of muscle resulting from the immobilisation a hospital bed following the onset of acute illness. He has also introduced the need for action to recover the strength and power lost by Deconditioning and the need for Reconditioning, which is distinct from, but obviously very closely related to, the clinical service called Rehabilitation.

Beliefs and attitudes
 
As always the wrong beliefs, namely that "rest is best", and pessimistic attitudes – for  example, “there is no point in giving my aunt a resistance band, she is 84 after all” – are the main factors that have to be addressed.
 
Getting stronger
 
The evidence is that people of any age can recover and increase strength and everyone needs a programme covering all the main muscle groups, particularly those of the quadriceps in the front of the thigh, and the core muscles of the spine and abdomen to maintain posture and prevent backache. The term resistance training is used for exercise that focuses on strength and your body weight is sufficient to increase strength, for example to increase the strength of your quadriceps muscles by standing up, a squat, as it is called. There are two types of resistance training -isotonic and isometric. In isotonic you are moving your muscles , for example by standing up from a chair, in isometric you are requiring your muscles to work without moving for example by doing a Wall Squat, sitting on an imaginary chair with your back against the wall, or by doing The Plank, forearms on the ground, body straight, balanced on your toes.

The benefits are huge, particularly for women and the older you and the more long term conditions you have the greater the benefit. The best plan is to find a trainer or go to a gym or go online and use the NHS Strength and Flex plan.  

The NHS Live Longer Better system emphasises the need for people to be informed and enabled to increase stamina, suppleness, skill and strength and this is one of its priorities which will be helped by the Publication of the Report of House of Commons Select Committee on Health and Social Care on Healthy Ageing; physical activity in an ageing society