Why Do My Legs Feel Heavy Running? – Complete Guide to Tired Legs

There is nothing worse than waking up to tired and fatigued legs from training. However, as a runner, it is something we tend to get used to. This often results in legs that feel heavy during and after running. So, what causes your legs to feel heavy running?

In this article, we look at the main cause of why your legs feel heavy running. So, continue reading to find out more.

Why Do My Legs Feel Heavy and Tired Running?

As a runner, there are days when our legs feel amazing, and other days where they feel slow, tired, and sore. This is normal for most types of endurance athletes. However, if it is something occurring regularly you may need to look at what is causing this.

So, why do my legs feel heavy and tired?

There are a few reasons why you might experience a heavy and tired feeling when running. Some of these reasons are:

– Overtraining
– Lack of recovery
– Increased mileage
– Poor running form

If you are experiencing a heavy feeling when running, it’s generally no concern most of the time. As an endurance athlete we are constantly on our feet logging miles, and trying to improve our fitness. So, generally, the build-up of fatigue is usually the cause of feeling heavy and tired when running.

However, this feeling shouldn’t last more than two days. Your training program should take into account your fatigue each week and month. So, the days where you start to feel heavy in the legs should be followed by a recovery run soon after.

If you are experiencing your legs feeling heavy running more often than not, you are not allowing enough recovery in your training. The lack of recovery not only gives you a feeling of heaviness in the legs but also affects your training.

Another cause of your legs feeling heavy when running is increased mileage. When increasing your mileage it is quite common to have a heavy feeling in the legs. However, this usually passes as the body adapts to the increased mileage. That means if you experience a heavy feeling after increasing your mileage, you should plan in a recovery week after 3-4 weeks of increased mileage. This will help shed any fatigue you may have generated from increasing the duration of your runs. Doing so will also allow you to continue to increase your weekly volume.

Tired Legs When Running? What Should You do?

If you experienced tired legs when running, there are a few things you can do.

– Turn your planned run into a recovery run
– Shorten your run
– Run as planned
– Take a complete rest day
– Replace running with cycling or swimming

Generally, it is ok to keep running when your legs feel heavy. However, you first must understand the scale of the fatigue.

If it is a general feeling of tiredness, replacing your planned run with a slow recovery run can help put the spring back in your bounce. It will also help loosen up the muscles so you can complete the following day’s training as planned.

If you are struggling to even run slow, you may want to replace your session with cycling or swimming. Alternatively, a complete rest day maybe even wiser.

Only you can decide whether you need to rest or not. However, some tools that can help you make an informed decision and these tools are your heart rate monitor and GPS watch.

Heart rate monitors can help you understand how bad the fatigue is. For example, if you cannot raise your heart rate during exercise, it’s a sure sign you are fatigued. There is also a chance (if it lasts for some days) you are getting sick.

Other things like your resting heart rate can also help you make an informed decision about whether you should train or not. An increased resting heart rate of more than 15 beats per minute, maybe a sign that you are over trained, tired, or picking up an illness.

A GPS watch can also tell you a similar story. If your legs are heavy and you are evening struggling to run at the same speed you usually do. It is a sure sign you are tired.

Tired Legs After Running – Is it Normal?

While we have mostly spoken about why your legs feel heavy and tired running, there is the feeling of tired legs after running. Is this normal? And how often should your legs feel tired after running?

For most athletes, not just runners. It is normal to experience tired legs after training. We are constantly pushing our bodies to the limit, both with intensity and volume. However, we shouldn’t have tired legs after running every day.

Tired legs after long runs, interval workouts, and tempo runs are quite common, but should generally pass by the next day if you have correctly planned in your recovery. If you are constantly experiencing tired legs after running every day, then you have not allowed adequate recovery. That means you need to include more rest days, or recovery runs into your training program.

Planning in a recovery week every 3-5 weeks can also help reduce tired legs after running, as it will help shed any fatigue you carry into the next block of training. Typically if you are taking a rest week every 4th week, it is normal to start to feel fatigued in the legs in the 3rd week.

Alternatively, booking in a regular massage can help prevent tired legs after running and prevent build up of muscular fatigue. Just remember to plan a recovery day after a deep tissue massage. Otherwise you legs will feel heavy when running.

Should I Run with Tired Legs?

To make improvements in your running there needs to be a balance between training fatigued and training recovered. Fatigue is necessary to improve and it can often help you get used to how the body will feel during a race.

However, as we have discussed in this article, there are benefits and disadvantages to running with tired legs.

If you are unsure what you should do, reach out to a qualified running coach. They can then help you make an informed decision whether you should run or not.