Does age matter when it comes to exercise? According to doctors, it can have an impact on the type of workouts you do.
Young adults should focus on building up their muscles and bones, while those who are between 35 and 65 should try to maintain their bodies and avoid injury.
Meanwhile, those above 65 should pay more attention to their balance and agility to prevent falls.
"Once you go beyond 30, it's all downhill," said Dr Tan Chyn Hong, an orthopaedic surgeon at Mount Elizabeth Novena Hospital. "You slowly start losing your muscle and bone mass."
He and other doctors agreed that the best time to build up muscles and bones is when you are between 18 and 35 - they will serve as a "buffer" later in life.
During this period, people have finished growing and are typically at the peak of their physical health. This means they can focus on high-intensity activities to build up strength and endurance.
WALK MORE TO STAY FIT
There are people who go to the gym for an hour and, after that, they sit down for the whole day... They are still not as healthy as people who go to the gym and have a high step count.
DR BENEDICT TAN, chairman of Exercise Is Medicine Singapore, on the importance of walking at least 10,000 steps a day, over and above whatever exercise has already been done.
"Generally, it's better to build up your fitness when you are younger," noted Dr Derek Li, a general practitioner at Raffles Medical.
"It's hard to do so when you're older, but it's easier to maintain what you already have."
When people approach middle age, their energy levels tend to dip. This is also the time when chronic diseases such as high blood pressure tend to show up, making regular exercise crucial.
Dr Benedict Tan, who chairs Exercise Is Medicine Singapore, said people tend to start losing muscle mass once they hit 30.
"You might therefore want to do more strength training to reverse or slow down that loss," he said.
He is part of a worldwide movement aimed at getting doctors to prescribe exercise as part of their treatment plans for patients.
Currently, the World Health Organisation (WHO) recommends at least 150 minutes of moderate aerobic exercise weekly for adults aged between 18 and 64. Alternatively, they can do 75 minutes of vigorous activity.
They should also do muscle-strengthening exercises - such as push-ups or squats - at least two days a week.
This means at least 12 repetitions of each type of strength exercise a day, said Mr Anand Sivayogam, a senior physiotherapist at Mount Elizabeth Rehabilitation Centre.
He also gave tips on how to tell if a particular workout falls into the moderate or vigorous category.
He said: "If you can talk but you can't sing a song, that's considered moderate. If you can't even carry on a conversation properly, that means it's vigorous."
In other words, what one person considers a low-intensity workout could be an intense one for someone who is far less fit.
Dr Benedict Tan stressed the importance of walking at least 10,000 steps a day over and above whatever exercise has already been done.
"There are people who go to the gym for an hour and, after that, they sit down for the whole day," he said.
"They are still not as healthy as people who go to the gym and have a high step count."
As a person gets on in years, balance usually starts becoming a problem.
This is because the systems that control balance - including the eyes and mechanisms in the ears - begin to wear down, Dr Li said.
Hence, those over 65 should consider exercises that help improve flexibility, agility and balance.
These can involve relatively low-intensity group workouts, such as taiji, yoga or dancing.
There is a caveat: It is a person's physical condition, not his age, that determines the type of exercise he can do.
"You cannot say that when you are 50 years old, you can't do pull-ups," said Dr Benedict Tan. "It's not about age per se."
One of the benefits of exercise for those over 65 - many of whom are retirees - is that it also serves as a form of mental stimulation.
Said Dr Tan Chyn Hong: "It becomes a social thing, and it's good for your mental health."
One person who can attest to that is stock dealer Mohan Adas Kandiah, who exercises an average of six hours a week.
The 56-year-old runs and cycles, and even travels to Malaysia to go on long walks with his friends. For him, exercising has become a way of life.
"It's hard to explain, but it gives me a lot of joy," he said. "It's something that I would find very hard to go without now."