The intensity that you run at not only dictates your body’s heart rate but also the amount of calories that you must burn in order to fuel the muscles that are being placed under demand. So then how many calories does running burn?
The following table provides rough figures based upon half an hour of running at various speeds.
|Speed (pace)||8 stone 9lbs||11 stone||13 stone 2lbs|
|5mph (12 min/mile)||240||298||355|
|6mph (10 min/mile)||300||372||444|
|6.7mph (9 min/mile)||330||409||488|
|7.5mph (8 min/mile)||375||465||555|
|8.6mph (7 min/mile)||435||539||644|
|10mph (6 min/mile)||495||614||733|
Source; Harvard Medical School – Harvard Health Letter – Jul 2004
Monitoring calorie burn during exercise is of course necessary if you are trying to lose weight. A daily shortfall of 1000 calories of your body’s requirements will result in weight loss of around 2lbs per week. Achieving that 1000 calorie deficit is much easier if you are also using exercise as a way to burn a chunk of calories that you’ve consumed, however, you have to work fairly hard to achieve meaningful results. The above table demonstrates that a 9 stone person running for half an hour at 5 miles per hour will only burn off 240 calories. Another way of looking at that is if you eat a Mars Bar (260 calories) you’ve more than undone your half hour of hard work. Food for thought!
Be wary of the figures being produced by your heart rate monitor (HRM) as well, very often they will display what is known as Total Calorie Burn (TCB) which is actually a combination of your calorie expenditure during exercise and your Resting Metabolic Rate (RMR; the number of calories you burn just existing) for the duration of your exercise session. This matters if you are using 2000 calories (women) as a baseline for your food intake and then using your heart rate monitor calorie reading to calculate how many extra calories you can consume on top of your 2000. Sorry to disappoint, but part of your 2000 calories is (probably) already included in your HRM calorie reading (some heart rate monitors display the net calorie burn but you will have to check with the manufacturer to be sure).
2000 calories per day for women or 2500 for men doesn’t take into account other factors such as the size of the person or their activity levels, if you want to calculate your 24 hour calorie figure for your resting metabolic rate you need to apply the following equation:
Mifflin St. Jeor Equation
For men: RMR = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) + 5
For women: RMR = (10 x weight in kg) + (6.25 x height in cm) – (5 x age in years) – 161
The number that you calculate will give you a baseline figure to work with when you are counting calories in an effort to lose weight or you are trying to ensure you have enough calories onboard to race competitively. Bare in mind that the number you generate doesn’t include any physical activity, not even walking from the settee to the fridge, so unless you are sitting down on a seat all day long you will burn off more calories than the figure suggests.
In order to work out your RMR contribution to a total calorie burn amount you have to use the following equation:
(RMR ÷ 1440) x Number of mins workout lasted
If we use an example from the above table, a 35 year old, 69kg (approx 11 stone), 160cm woman runs for 30 minutes at 6 mph, their heart rate monitor may very well tell them that they have consumed 372 calories (TCB), she looks at her heart rate monitor, congratulates herself in the knowledge that she only ate 1372 calories that day so she is 1000 calories below her body’s required 2000 per day (women) and well on her way towards her 2lbs of fat loss that week. Unfortunately she really only burned off an additional 307 calories.
Applying the above equation, 65 calories would have been burned off had she just sat down and not moved for the same time period. It isn’t a huge difference but it can make the difference when it comes to weight loss, especially if it is a daily recurring event throughout your weekly calorie intake.
Lastly, bear in mind that a person with more lean muscle mass will burn off more calories at rest than a person with less muscle mass. Besides the benefits to calorie burn if a runner adds 3lbs of extra muscle in total to their legs the benefits could far outweigh the detriment that the extra weight would have on the runner. I don’t know for sure but I’m willing to bet that Mo Farah weighs more now than he did when he wasn’t winning olympic and world gold medals. The major change he made in his training was that he started strength and conditioning alongside his running, I’m pretty sure as a result he will have added some muscle to his frame.
Our general advice would be don’t be too quick to consume extra calories in an effort to prevent hitting ‘the wall’, the wall is 20 miles away and if you’re not placing your body into a caloric deficit for weight loss then your body will have approximately 2000 calories stored and will be raring to go. Go easy on the consumable rewards for your hard work too!
Enjoy your running