How to Combat Heavy Legs When Running

Do you ever feel like you’re running through treacle? Getting heavy legs can be very frustrating, particularly if you’re training for a marathon or another long distance race. While heavy legs don’t feel great, the good news is that there are several things you can do to quickly address this issue - and get back to running free and easy.

Let's learn about some of the underlying causes of heavy legs when running, as well as some simple tips you can follow to prevent this from happening.

What causes heavy legs whilst running?

There are several likely causes of heavy legs when running - here are some of the most common reasons you might experience this.

Fatigue

By far and away the most common cause of heavy legs when running is fatigue and a lack of recovery time. If you increase your mileage or running intensity quickly, fatigue is likely to set in. Training causes small tears in your muscle fibres, and so your body needs time to recover and repair the damage (which in turn makes your legs stronger). However, if you don't leave enough time between training sessions to recover properly, then the accumulated damage will make your legs simply feel tired and unresponsive.

It’s worth noting that there are different kinds of fatigue too. If the feeling of tiredness goes away after a warm up or that you feel after a week of intense training, this is what’s known as ‘normal fatigue’. It usually goes away by itself. On the other hand, abnormal fatigue - which doesn’t go away after some recuperation and a light recovery run - is a potentially a bigger issue indicating overtraining.

Poor running form

Running form is another reason that your legs might start to feel heavy and slow. There are several mistakes you could be making with running form, but the most likely is the tendency to over stride.

Many runners pick their legs up fairly high and reach them forward. This puts a lot of additional strain on your legs, tiring them out fast. Instead, you should aim for quick, light steps, with your feet not lifting high off the ground or far in front of your body. For more tips, read our guide to running form. 

Too much weight training

Most marathon training plans will include some weight training sessions, where you perform various weighted exercises such as squats and lunges. However, if you overexert yourself during weight training workouts, then you will experience DOMS (delayed onset muscle soreness). While leg weight training is good, you  should only increase the amount you lift gradually, and balance running workouts and weight lifting sessions so they don’t work against one another

Nutrition and diet

Failing to get the right nutrients in your body might explain why your legs feel like lead. Most runners can get everything they need from a well balanced diet. So, look again at what you are eating, and ask:

• Are you getting enough carbohydrates? Carbs come from food such as pasta, rice, bread and potatoes, and are an amazing source of energy (it gets stored in your muscles as glycogen, which you use to power your runs).

• Are you getting enough protein? When you go running, the exercise will cause small tears in your muscles and so your body uses proteins to repair any damage – you’ll therefore want to get more of it on your plate (again, aim for about a quarter of each meal). Protein comes from a variety of sources including all kinds of meat and seafood, as well as eggs, lentils, and dairy.

• Are you getting enough minerals? To exercise efficiently, your body needs a variety of minerals including iron, sodium, potassium and magnesium. Generally speaking, these can all be found in a healthy balanced diet, but it’s worth thinking about what you eat and ensuring it contains all the nutrients you need.

• Are you well hydrated? Not getting enough fluid could also leave you feeling fatigued. Read our article on hydration for running to learn more. 

We’ve put together a complete marathon training nutrition guide - read it here. 

Rule out medical causes

In most cases, feeling that your legs are heavy when running will be down to one of the factors outlined above - and can be solved with some relatively simple changes. That being said, there could be underlying medical issues that are making your legs feel heavy - including varicose veins, poor circulation, and diabetes. If you’re concerned there could be a medical cause, then it is always worth speaking with your doctor.

How can you prevent heavy legs when running?

Preventing the underlying causes of heavy legs when running is normally quite straightforward. Here are some simple steps you can take to avoid it from happening.

Rest!

As noted above, one of the primary causes of heavy legs when running is simply overexertion. If you have recently upped the mileage, speed or frequency of your runs, it is likely that fatigue is setting in. Take a few days away from running, then gently ease yourself back into training.

Warm up properly

Many runners forgo proper warm-ups before their training sessions, but this means that their bodies are not fully prepared for the exertion ahead - so they’re more likely to cause damage to muscle tissues, bones and joints. Follow our running warm up tips to make sure your body is primed and prepared for each session.

Perform proper post-run stretches

Just like with warmups, many runners forget to stretch out after their runs. This means you miss a  vital opportunity to help your body recover. Stretching encourages blood flow to the muscles - which is a vital part of the repair process - helps clear lactic acid and increases flexibility. Read our blog on stretches to learn more.

Wear correct running shoes

Another way to prevent heavy legs when running is to ensure you are wearing a proper pair of running shoes. Your footwear should be lightweight so you can move freely and easily, and it should also offer plenty of cushioning to reduce the impact of foot strikes on hard surfaces. Browse our women’s running shoes and men’s running shoes to find the right footwear for you. 

If your legs feel heavy when running this is rarely a serious problem. With a little rest, some changes in form, footwear, stretching and diet, you’ll soon be running with comfort and ease again.