Running will alter your body composition. But what does that really mean? We explore how running affects muscle and body fat.
Body composition refers to the makeup of your body: how much of it is muscle (lean tissue), how much of it is fat (adipose tissue) and how much of it is bone, water and more. When we talk about body composition for runners and other athletes, we tend to only refer to subcutaneous fat (the body fat just underneath the skin) and muscle (lean tissue), although managing visceral fat (around your organs) is just as important to health and wellness. As a quick aside, there’s no need to refer to anything as “lean muscle”: all muscle is lean by definition!
It’s not possible to turn body fat into muscle, and nor will muscle turn into fat. It’s simply not possible (just as it’s not possible for your hair to turn into your hat, or your rug to turn into your carpet). What can happen, of course, is that you can lose fat and gain muscle. Or (less desirable), you can lose muscle and gain fat. But one type of tissue can not morph into another.
A strong, lean physique is one with enough muscle mass to be shapely and healthy, covered in levels of body fat high enough to promote healthy hormones and low enough to avoid health complications.
So what happens to body composition when we take part in cardiovascular exercise such as running? Creating a calorie deficit will result in a reduction in body fat, so our body composition will change in that our body fat percentage will go down. But our lean mass (muscle) is unlikely to increase by much through the activity of running, because it doesn’t challenge the muscles with enough resistance for them to rebuild and grow.
So, whilst running (combined with a healthy diet) will help reduce body fat levels, we need to look to some sort of resistance training to build muscle. Why do we want to build muscle? So that our body shape changes for the better and we do not end up “skinny fat”. Adding lean tissue to our bodies means we will be stronger, less prone to injury and will look better! It’s muscle that makes for a firm, shapely body, after all.
Combine your love of running with some sort of resistance training (body weight exercises, weight training, kettlebells or yoga are all good) and you will have a healthy, strong, fit body which performs well and looks great.