Why do so many gym-goers head instinctively for the treadmill? Is it because they want to improve their aerobic ability? Sometimes. Because they envy the carcass-with-lungs physique of long distance runners? Not in my experience. No, its because they want to burn as many calories as possible in their gym session, in the hope that these magic calories will remould and refine their bodies.
Unfortunately, aerobic exercise cannot sculpt anything and those who rely on running to tone their physique may find their buns of steel are decidedly doughey. A glance around in a starting pen for any major marathon, where almost all competitors will have spent several hours a week running for a minimum of five months, will confirm that there is only so much support lycra can do for wobbly bits!
So doesn’t pavement pounding do the job? The problem is not the running per se, simply that aerobic activity has limited effects on the body. Aerobic exercise (any activity that is sustained at a consistent pace) uses your slow-twitch Type I muscle fibres, which burn a combination of carbohydrates and fats, and I often measure this using a trainsmart monitor complete with gas mask. Running at a fast tempo will mean your body will use almost exclusively carbohydrates; fats, your slow-release fuel, hardly gets a look-in. My data shows powerwalking or slow jogging the most efficient way to burn fat for most people. Typically, running uses 10kcal/min with just 15% fat usage, compared to 7kcal/min with 80% fat usage.
Clearly, for most people, running is a poor fat-burner. Unfortunately, its not good at sculpting the muscles either – the slow-twitch fibres used during running will improve their abilities to exchange oxygen (eg become more efficient) but even a trained slow-twitch fibre is limited to growing to 120% of its untrained size. Cycling and aerobic classes fit into this category, too. So, lots of sweat + lots of calories burned = little fat reduction and little response from muscles.
I suppose some fat loss is better than none, and you will at least get better at running! If running is important to your sport, or you enjoy it, then this is clearly a very valid reason to continue pushing hard. It’s not as if running has no benefits – as with most exercise, individuals can expect an improved cardiovascular response, improved stress patterns and reduced blood pressure. As someone who has completed four marathons, I can tell you there is nothing wrong with running – provided you know what to expect from it. I should also point out that, for around one in six individuals, aerobics burns fat very effectively (these people are classically labelled ectomorphs).
But for the majority of us, the same rules apply. If you want to improve the shape of your body, then you will need to increase your lean mass (muscle) and reduce your bodyfat. The most efficient way to do this is resistance training. This is press-ups, chins, squats and weight training with benches – this type of training overloads your fast-twitch Type II muscle fibres, raising your metabolism (and the rate at which you burn fat) for up to 72 hours after an intense workout. It improves your lean mass, and therefore your basal metabolic rate (the amount of energy your body uses up, just to stay alive, before movement).
There is always more than one thing to consider when looking to achieve success in regards to health and fitness. But very few of mu clients have found what they are looking for on the treadmill. Calories are just a form of energy and busting a gut to burn them blindly will not always generate the results you are after – but overloading the fibres most likely to get you a return makes sense and is the difference between working hard and working smart!