Has a sudden decrease in athletic performance, lack of endurance, and slower times left you concerned about your running?

We all have our days where we simply just feel slow and can’t even think about running at the pace we normally do run at… If these types of days are occurring more and more and closer together then it might be time to get to the bottom of it and find out what is really going on and if it’s a cause for concern.

Let’s have a look at what could be some of the causes of your drop in running performance and loss of endurance. There are a few common ones…

What’s Behind Your Sudden Decrease In Athletic Performance

There are actually quite a few things that could be at play that are causing your sudden drop in running pace and loss of stamina.

Stamina: the ability to sustain the prolonged physical effort.

Age is of course one of the things that can cause us to recover slower and to get more tired and therefore to run slower times.

Pros & Cons Of Running After 50 – What You NEED To Know

If you are a female, one of the things that you are more susceptible to (more than males), even though it’s not exclusive to females, is having low iron levels.

I would definitely advise checking whether you have low iron or low ferritin levels.

Another cause for a sudden decrease in athletic performance could be overtraining.

In terms of blood tests, doctors can look at things like Creatine Kinase or other inflammatory markers in the blood.

Then of course, even if you are showing no obvious symptoms of illness, there are various illnesses that are relatively asymptomatic that can cause a sudden decrease in athletic performance and loss of stamina.

Fatigue and slowing down are big symptoms, so even though you are asymptomatic at rest, they may be affecting you during exercise.

What To Do If You Have Lost Your Running Stamina


Taking some time off from training and just resting could also arrest the sudden decrease in athletic performance.

I would suggest taking a few days off with no running at all. 72 hours of good, solid rest.

Then at least a week of very easy, short runs and if there isn’t a significant improvement in your athletic performance, then you do need to start looking at things like iron levels in your blood.

It may also then be worthwhile having a look at thyroid function.

If the rest doesn’t work then I would suggest a consultation with a sports physician because there are a number of factors that can cause this sudden decrease in athletic performance.

Check out this Practical Guide To Running Recovery.

10 Reasons Why Your Running Performance Has Dropped

  • Overtraining
  • Not eating enough nutritional meals
  • Not recovering correctly
  • Under or over-hydrating
  • Only running. (Your training should include mobility work, strength training, and cross training)
  • Not running long runs.
  • You’re not getting enough quality sleep
  • You’re aging
  • Not enough pace variety – running too hard all the time.
  • You may be experiencing a lot of stress.

We are HUGE advocates of mobility work here at Coach Parry and have created a mobility flow that you can do at home. You can access the mobility flow by clicking here.


With a passion for high performance sport – Lindsey Parry is one of South Africa’s most widely recognised coaches. Having led a team to the London, Rio and Tokyo Olympic Games as well as the Commonwealth Games in Edinburgh, the Gold Coast & Birmingham, and coached both triathletes and runners onto podiums of some of the world’s most illustrious races, Lindsey has a unique ability to understand what it takes to succeed at any level and thrives on coaching, motivating and inspiring others to do the same – whether it’s on the track, on stage or behind a mic.

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