Does Running Make Your Legs Bigger?

The effects of Running on Legs

The effects of Running on Legs

My first attempt at working out to lose weight had me jogging in the park for about an hour. After some time, I wasn’t feeling as challenged so I began running faster and longer.

However, I soon grew dismayed that while I was losing some weight, my thighs appeared to be getting bigger! At 5’1 inches, my goal was to reduce fat in my legs as opposed to building muscles/mass. Since my legs weren’t trimming down, I started to look into whether running caused legs to get bigger.

But do any research on the web and you will be confused for days. What you’ll find is that there are a lot of people who swear that running is the only thing that will actually make their legs smaller, while another set will have exactly the opposite effect, like me. So what exactly is going on here?

Cardio exercise will burn calories for sure, so one would think running, which is a great form of cardio, would melt the fat off your body. And this is actually true. Even ectomorphs will find their upper bodies responding quickly to this form of cardio, but the magic question is will running effectively target and get rid of the stubborn fat most women hold on to in their legs? Unfortunately, the answer is not so cut and dry.

You see, there are a lot of variables to take into consideration such as the length of time spent running, the intensity (whether you are activating slow twitch or fast twitch muscles), your current body fat and muscle composition, the ability for you to build muscles, your muscle memory, your perception, the effects running have on your appetite, etc.

Obviously, I can’t cover all the varying factors in this one article, so I will just focus on the big ones.

First let’s discuss the length of time/distance you spend running.

Running hard for a long period of time (2+ hours) and covering upwards of 8+ miles of ground (especially if done every day) is not necessary to lose fat. In fact, it can be considered over training. Not only will the muscles become engorged with blood and the lactic acid fluid released in your legs make them swell and appear bigger, but once the torn muscles heal from all the tears and strain, they will grow.

One factor many people erroneously belive is progressive overload from running will cause muscle gains and make their legs bigger. First, yes, progressive overload does cause muscle growth. This means if you were able to lift 5 lb. weights and complete 20 sets before failure, the second you are able to do 21 sets you have achieved progressive overload and will experience gains. However, running doesn’t put any more resistance on your leg muscles so there won’t be muscle gains. The inches on your legs will increase though if you are running 3 miles for one week and then start doing 4 miles the following week, provided you are doing so at a very fast pace and engaging your fast twitch muscles.

Does this mean that you should continue to do 3 miles of running forever to lose the fat from your legs?

Not quite. Even more food for thought, if you run often chances are you will get better at it. As you get fitter, the work required to do 3 miles will lessen. Keep running at 3 miles and instead of burning 400 calories, you’re burning 200, resulting in legs that will stay the same and may start to even gain fat if you continue to eat as you were when burning 400 calories.

If you try to run the 3 miles faster, you leave the aerobic zone and enter the anaerobic zone. And we already covered what will happen when you try to run longer (eventually you will adapt to that and have to keep increasing the length of your runs to burn the same amount of calories, which is not sustainable or if done at a high intensity will build up your leg muscles). It doesn’t end there. Let’s say what used to take you one hour now takes you 30 minutes to complete. It takes about 20 to 30 minutes before most people deplete their glycogen stores and start burning fat (if running in the steady state, aerobic fat burning zone), so the more efficient you get, the less fat you are likely to burn/lose.

Are you starting to see why the act of running may make your legs bigger? The most common reaction to us getting more efficient at running is to push ourselves harder. We might try to beat our old time by running faster (thus exiting the aerobic state) and/or we do an extra mile or two (building up the muscles in the legs). Oh vey!

Next, let’s look at the component of your diet and the effect running has on your appetite.

A lot of runners have this cardinal rule that fueling up on carbs is necessary before and after a long run. The thought process is that they will require a lot of energy to complete their workout, which carbohydrates provide. Thus, the more carbs, the longer and more intense the individual can work out. Then, after the workout, they are told they have to fuel up on typically carb laden protein shakes/bar to repair their muscles or they feel so hungry that they scarf down the first thing in sight since they’ve ‘earned it’.

The first issue is that if the body is burning carbs, it isn’t burning stored fat. In fact, by not introducing carbs before you train, you force the body to turn to fat for fuel. This is called being a fat burner or fat adapted. In order to lose the fat from your legs, your body has to burn the stored fat.

The second problem with carbohydrates is that they have been proven to be addictive and increase your appetite, generally for more carbs and sugar. Fighting real feelings of hunger and craving is a losing battle, and most women will end up caving eventually. Of course, the more of these foods that you ingest the higher chance that you will exceed your total daily calorie energy expenditure (the amount of energy you burn per day) and gain fat/weight, which unfortunately for many women likes to be stored in our legs/thighs.

Secondly, when you eat carbs your insulin levels will experience a spike.  are stored in the body as sugar, which is Carbs also prevent fat loss. So, .

There are a lot of factors to take into consideration and obviously I can’t cover them all in this blog post, but hopefully this article will give you insight into understanding why some people can melt inches from their legs while running while others gain just looking twice at a track.