SINGAPORE – Is there an ideal time of the day to exercise? Experts are divided.

Project manager Jingxi Lim, 30, likes to schedule her gym workouts early, before her day gets busy. However, the avid boulderer finds that her favourite climbing sport is more manageable in the later part of the day.

It is easier to schedule time at a climbing gym in the evening. Also, she says: “I feel stronger towards the evening because it takes time for my body to warm up.”

Does it matter when you work out? Experts in healthcare and fitness say no. But it can also be yes, depending on your goals.

Dr Reyor Ko, a general practitioner with private medical company Doctor Anywhere, says the idea that exercising at different times of the day might yield different benefits is based on circadian rhythms.

“This is our body’s natural clock that influences physical, mental and behavioural changes within a 24-hour cycle,” he says.

“However, the scientific evidence regarding the optimal time for exercise is quite mixed.”

While some studies tout morning workouts for fat loss, others find evening exercise leads to improved performance and strength.

Here are some factors to consider when scheduling your workout.

Aim for at least 150 minutes of moderate exercise a week

Doctors advise regular exercise to improve and maintain one’s mental and physical health.

Dr Stephanie Ong, associate consultant at Changi General Hospital’s Department of Sport and Exercise Medicine, says: “Exercise plays a crucial role in health management by improving cardiovascular health and fitness, helping one maintain a healthy body weight, as well as reducing the risk of developing chronic diseases such as diabetes, high cholesterol and hypertension.”

She adds that exercise can reduce the risk of cancers such as those of the colon, breast, bladder and lung. It can also boost one’s mood and mental well-being.

The Singapore Physical Activity Guidelines released in 2022 recommend that adults aged 18 to 64 engage in at least 150 to 300 minutes of moderate-intensity aerobic activity a week.

Adults should also do strength-training activities at least two days a week, while those over the age of 50 should fit in balance and flexibility sessions as well.

Dr Ong says: “Currently, there are no guidelines as to what the best time of the day to work out is. Research suggests that exercising at any time of the day is beneficial for health and fitness goals.”

She adds: “The most crucial factor is consistency in exercise, so it is essential for an individual to pick a time that allows you to exercise regularly.”

Morning workouts may help build the exercise habit

If you are looking to build an exercise habit, working out in the mornings may help.

A study published in 2017 in the journal Health Psychology followed 48 students as they attempted to develop a healthy habit of stretching. Those who stretched in the morning developed the habit faster than those who stretched in the evening.

Dr Lim Wee Peng finds the study inconclusive, but the family physician and deputy medical director of Parkway Shenton does think that morning workouts are ideal for those who want to prioritise fitness and prefer consistency in their routine.

“Morning exercise kick-starts your metabolism, boosts energy levels and sets a positive tone for the day,” he says.

Mr Dean Leigh, who is Virgin Active Singapore’s national personal training manager, agrees that morning workouts can help people stay consistent with an exercise programme.

Scheduling exercise for later in the day makes it easier to miss workouts because of tiredness or having to work late.

However, he cautions that the quality of a morning workout could be compromised by bad sleep, or feeling too hungry or weak to give one’s best.

Not everyone is able to exercise first thing in the day. Dr Ko says: “I am just not a morning person, so all of my workouts are done in the afternoon or evening.”

He adds: “In my practice, encouraging people to exercise at a time that feels most natural and convenient to them has been the best approach to maintain regular physical activity and reap the health benefits associated with it.”

Afternoon workouts have reduced risk of injury, but avoid the heat

For those who cannot manage a morning workout, afternoon exercise might be better.

Dr Lim of Parkway Shenton says that towards the afternoon, body temperature and muscle flexibility are higher, leading to better performance and reduced risk of injury when exercising.

Are there other benefits? A study published in 2023 in the journal Nature followed more than 92,000 people in the United Kingdom for seven years and observed that moderate to vigorous physical activity at any time of the day reduced all-cause mortality and death from cardiovascular events.

The study indicates that this effect could be more pronounced in those who were most active from mid-day to the afternoon – 11am to 5pm.

Ms Lee Shi Hwee, physiotherapist at Singapore General Hospital, notes that these are still observations and more studies are required to confirm the findings.

“Exercise at any time of the day yields benefits,” she says. It is more important to exercise consistently.

Ms Heather Thomas, classical Pilates instructor and founder of Flex Studio Singapore, says that forming a new exercise habit is also about breaking bad old habits. Scheduling a lunchtime workout could help break bad habits, such as sitting for long hours at your desk and eating while working.

Her preferred time to exercise is in the hours after lunch, since this is when she can best focus on her practice.

“It’s important to have the mental space to say, ‘I’m here and I’m in my body.’ If you’re working out in the morning but concentrating on what you will be saying in a meeting at noon, you’re missing out,” she says.

As temperatures rise during the afternoons, and especially during hot months such as May, experts suggest taking extra precautions with afternoon workouts.

Dr Ang Kian Chuan, an orthopaedic surgeon with private practice SBF Sports and Hand Centre, says: “Common sense precautions, like keeping well-hydrated, appropriate clothing, activity moderation, would all be important to avoid adverse effects.”

Dr Ong says to watch out for signs of heat exhaustion, such as weakness or fatigue, dizziness or light-headedness, nausea or vomiting, headache, muscle cramps, thirst, heavy sweating and an elevated body temperature. Emergency treatment should be sought in case of loss of consciousness, confusion, seizures or other serious symptoms.

Ms Lee says to drink fluids before, during and after workouts. “Aim for 400ml to 600ml of water two hours before, and small amounts every 15 to 20 minutes during exercise. For workouts more than 90 minutes, you can consider replenishing electrolytes with a sports drink,” she says.

“Secondly, choose lightweight, breathable clothing in light colours to facilitate air circulation, and apply sunscreen to protect your skin from harmful UV rays if exercising outdoors.”

She adds: “Consider opting for activities such as swimming or cycling, which allow for better heat dissipation compared with high-intensity workouts. You can also choose to exercise in shaded areas or use a portable fan for instant cooling relief.”

Evening workouts may affect sleep

Regular exercise can help you sleep better at night, but opinions are divided on how evening exercise will affect sleep quality.

Dr Lim says that research shows evening exercise has a beneficial effect on sleep. “However, individuals who engage in high-intensity exercise, such as interval training, less than one hour before bedtime may experience poorer sleep quality and take a longer time to fall asleep.”

Dr Ong says that exercise raises the heart rate, body temperature and adrenaline levels, which can make it more difficult to fall asleep.

Mr Leigh says that some people take caffeinated drinks before their workout, which can make it harder for them to fall asleep later.

Yet if evening workouts fit your routine best, that can be an advantage, he adds. “Strength and power workouts are better later in the day, when your body is warmed up.”

Mixing it up for best results

Working out at a set time every day can help build consistency, but do not let the habit hobble you.

Mr Hansel Sng, a trainer at boutique gym Tribody Fitness, says that one of the biggest barriers to a regular exercise routine is changes to a daily schedule.

Clients often stop coming to the gym regularly because they do not know how to fit exercise into their new routine.

“A lot of people get discouraged if they can’t come at their regular time,” he says.

His advice? “Don’t be afraid to mix up your workout timings. There may be small benefits to exercising in the morning, or the afternoon, but not if it messes up your day.”

Housewife Sandhya Manuel, 50, used similar principles to restart her gym routine in 2023. An avid trekker and gym-goer until 2017, the mother of three had then fallen out of the exercise habit.

She signed up for a gym membership at the end of September 2023 and now goes in the morning about three times a week. “I prefer mornings because I get very lazy by the evening,” she says with a laugh.

She does not mind skipping the occasional workout in order to spend time with family and friends. “I skip only for a good reason,” she says.

That is the right attitude, says her trainer, Mr Sng. “Don’t feel guilty if you miss a workout session.”

Being consistent in the long run is more important, he adds. “You get the benefits of exercise only if you work out long-term. The best timing for a workout is what works for you.”

The Bottom Line: Exercise regularly and at a time that works best for you and your schedule. Adults should aim for at least 150 minutes of moderate intensity aerobic exercise a week, as well as at least two strength-training sessions.