Does it matter what time you exercise? Matt Roberts, The Times Health Club fitness expert, sorts the larks from the owls

KEEPING AN EYE ON THE CLOCK

For many, the pressure of work, social and family commitments means that when it comes to exercise it is often more a case of “Can I exercise at all this week?”, as opposed to “What time of day is most effective for my body?” Assuming that you are flexible, what is the best time of day?

There are many schools of thought on this, taking into consideration factors such as digestion, joint mobility, circulation, metabolism and even your biorhythms, and it is one of those areas that has led to conflicting ideas, leaving everyone confused.

At the risk of confusing further, I want to focus on the most effective time to work out, based on burning the greatest amount of calories, because let’s face it, for most people this is the main reason for working out.

To burn up the calories you need to raise your metabolic rate, the rate at which your body burns energy, for as long as you can manage and then use an approach that will keep your basal metabolic rate – the rate your body burns calories at rest – high at all times, whether you are awake or asleep.

Each time you exercise, your calorie burning rate “spikes” and then slowly returns to the basal rate when you finish. The rate of decrease is reasonably slow and you burn calories after you finish exercise for up to several hours.

If you do an office job where you spend most of your time sitting, your body has no need to work particularly hard and your metabolism slows considerably. When you sleep it slows to its lowest point of the day.

Based on this principle you could assume that the greatest level of success is achieved by regularly raising your heart rate and consequently your metabolic rate throughout the day.

MULTIPLE WORKOUT PRINCIPLE

If you had to go out and kill your meal a few times each day – like our caveman ancestors – you would lose weight quickly. While the image of this happening on the streets of Britain is absurd, the basic premise is sound. You would raise your metabolism to a high level for 30 minutes and then rest for several hours, during which time your metabolism would slowly fall, followed by a repeat of the same process. Throw in the metabolism-raising effects of eating and digestion after your hard-earned meal and you have a recipe for good calorie burning.

How can you put this into practice in the modern world? Go to the gym twice a day, or go for a run once and to the gym once, or maybe use your commute to work on a cycle as a genuine workout session (not in work clothes, however, you need to get really hot and sweaty or you are not really exercising). This approach gives your daily metabolism profile an effective boost. The obvious downside is that it is time-consuming and may be impractical. It also means exercising twice a day, which you may either dislike or grow to dislike pretty quickly.

MORNING WORKOUTS

If sleeping induces the greatest fall in metabolism, exercising in the evening is a wasted opportunity to sustain an elevated calorie burn rate, so morning is the better choice. But your body is not a simple on/off mechanism, particularly after you reach your twenties. It takes time to increase circulation levels and to stretch the muscles into good joint mobility. On that basis, an early workout is not ideal, even if it maximises the “awake hours” over which your metabolism will be raised, particularly if you are going to boost your heart rate only once a day. And while the effects of eating after a workout are good, exercising on an empty stomach may mean that you lack the fuel required to work out hard.

Why not eat breakfast at 7.30am, which will give you more than an hour to digest your meal if you choose to exercise at 9am. By then your body will be mobilised, your mind alert and ready for physical challenges and you will still get the maximum return for the day in terms of calories used.

Ultimately working out three to four times a week, twice a day for 30 minutes is best, once at 9am and the next at 3pm – just as you are in the middle of your working afternoon. If it’s impossible to fit in a mid-afternoon workout, or you just can’t face working out first thing in the morning, don’t beat yourself up about it. Doing a workout will have a significant effect on raising your metabolic rate and burning those calories more effectively.

Find out more about Matt Roberts at www.personaltrainer.uk.com

CLICK HERE TO JOIN THE TIMES HEALTH CLUB

Times recommends

• The grim reality of life as an air stewardess
• 50 of the world's best design blogs
• Video: Georgia Jagger on fashion and her mum's clothes