AMY PACKER

Many endurance athletes don’t reach peak performance levels until they are in their 30s, and this is the time for everyone to work on stamina and strength.

Focusing on activities to boost stamina slows the loss of muscle mass, which begins in our early 30s. As muscle burns more calories than fat, this decline makes it harder to maintain a healthy weight.

More importantly, as the heart is primarily muscle, this loss also increases the risk of heart failure.

Our lung capacity is also declining by now, though we have so much to spare most people won’t notice this until they are in their 50s or 60s. Dr Lindley says there is nothing we can do to prevent the changes within our lungs which reduce their capacity, but exercise will make them work more efficiently.

He explains: “The less oxygen our respiratory muscles use for breathing, the more oxygen there is available in the bloodstream for other exercise. And if you make the skeletal muscles more efficient, there’s more oxygen available, so you can work harder.” Any activity which gets you to the point of breathlessness and can be maintained will boost respiratory function.

However, we are often juggling jobs and children at this time of life, so the key is to build exercise into your daily routine.

BJ Fogg, a behavioural scientist based at Stanford University and author of

Tiny Habits: The Small

Changes That Change Everything, explains: “You create any habit you want by making the habit super-easy, finding where it fits into your routine.”

You might not have time for an exercise class, but you can easily do some star jumps while you watch the TV news, or squats while the kettle boils.

Celebrating such small steps may sound silly, but Fogg explains: “By feeling good at the right moment, your brain recognises and encodes the sequence of behaviours you just performed, and this speeds up the habitformation process.”

But be sure to build in some more sustained activity. One way to do this is to look for activities such as bike riding and ball games the whole family can enjoy.

For optimal benefits in a limited time, Dr Brooke-Wavell recommends interval training — where you alternate bursts of high-intensity exercise with slower recovery phases. And Sammy Margo adds: “Work on your legs and glutes as they are your biggest muscle groups.”

Support this with a diet that includes iron and protein-rich foods such as red meat and leafy greens.

Muscle and bone loss accelerate at this time, and for women this is particularly true after menopause.

If you have always been active, you will begin to notice a widening gap between yourself and friends and family who have not exercised regularly.

Dr Brooke-Wavell says: “Working on muscular strength becomes really important. Some women will lose up to a third of their bone mass and a third of their muscle strength over their lifetime.”

And the good news is that it’s never too late to start.

One of Dr Brooke-Wavell’s studies showed that just five minutes of exercise a day will improve bone density within six months. She asked a group of postmenopausal women to do 50 hops a day — always on the same leg — and, after six months, bone density had improved in the hopping leg and deteriorated in the leg which hadn’t been exercised.

Balance becomes increasingly important and this relies on strength in the lower legs and core. Exercises such as tai chi, yoga and Pilates, which use muscle isolation and very controlled movements, will build and strengthen these muscle groups and reduce the risk of falls.

Support muscle and bone strength by eating foods containing generous amounts of protein, vitamin D and calcium.

“It’s all about strength training,” says Sammy Margo. “There has been a lot of research linking good muscle strength with a reduced risk of cognitive decline.”

However, arthritis, old injuries and general aches can make exercise a challenge at this time of life.

If this is an issue, try swimming and water aerobics as the water helps to support your body weight.

Dr Lindley suggests: “Resistance training is helpful, and it’s something everyone can do — just hold a tin of beans in each hand and do some bicep curls as you watch TV.”

Simple tricks like not using your arms to push yourself up from a chair or sofa will also help maintain muscle in the legs and core.

Whatever your age, or fitness level, the experts agree on the importance of setting realistic goals. Start the day with some gentle stretches — it gently wakes up muscles, reducing the risk of aches and injuries, and a recent study found it improves vascular function and circulation in just 12 weeks.

Aim to do something every day, but don’t make exercise a chore — you’re far more likely to stick with something you enjoy.