Methods or Measuring Fatigue in Runners

Hi there! 👋

The nights have started drawing in here in the UK, but there’s still a little more summer running to squeeze in before we move into autumn conditions. I hope you have some good plans to make the most of it! 

In this month’s newsletter I’m going to be talking about methods you can use to monitor fatigue and their relative pros and cons. 

Balancing freshness and fatigue

First it’s worth saying that a good training program should have you feeling tired at certain points in the week e.g. after you’ve applied a big training stress (done one or two hard sessions). This fatigue is necessary to signal your body to adapt and get fitter. 

However, you should also have points in the week where you’re feeling relatively fresh. These fresher periods are key, because this is where your body is actually given space to adapt - it needs time and energy to build new mitochondria, capillaries, muscle tissue and so on. 

Ultimately, we need both the fatigued periods and the fresh periods on order to see fitness progression. 

It’s common to fall into a trap of feeling as though you should be tired all the time from training… Surely, if you’re feeling well-recovered, then you’re not training hard enough?

However, if you’re constantly in a state of fatigue, your body won’t be adapting optimally to the training. You’ll also be too tired to perform training sessions (particularly longer runs, or high-intensity sessions) to a good quality. If this pattern is continued, it can lead to a state of overtraining, which can be very disruptive to training, and can have serious long-term health implications. 

Conversely, if you’re never really feeling particularly tired from your training, it’s likely that you’re not doing enough, and you’ll be losing (or at best maintaining) fitness. 

It’s wise to monitor your fatigue levels, to make sure you’re getting a nice undulating cycle of tiredness and freshness, and to ensure you’re doing the right types of sessions on the right days (e.g. not attempting a hard interval session when you’re already tired). 

Monitoring Fatigue

Some methods you can consider when monitoring your training fatigue are as follows: 

• Mood, motivation and sleep quality. These are all really great indicators of fatigue. If you’re feeling less motivated to run than normal, or have been finding yourself a bit irritable, low or even lacking in sex drive, these can all be signs of fatigue. Reduced sleep quality can be another signal. There are formal mood questionnaires you can complete (e.g. the ‘profile of mood states’ (POMS) questionnaire). But in my view, simply reflecting on your mood, motivation and sleep over the last 24-48 hours can be far quicker and just as effective. 

• The stairs test. Running up a flight of stairs is a really simple way to gauge fatigue levels. Pay attention to how ‘bouncy’ or ‘powerful’ you feel when running up the stairs, and how achey or sore your legs are. You can even rate this daily on a scale of 1-5 to get a quantitative picture of how this varies day to day. 

• Post Warm-Up Rating of Perceived Effort (RPE). Simply doing a bit of running can often give you a good indication of how tired you are! I’d recommend paying attention to your RPE after the first 10-15 mins of running, once you are warmed up. If you’re feeling sluggish or your pace or running wattage looks low relative to your effort level, then it might be wise to cut your session short or reduce the intensity. 

• Heart rate. There are a few different things you can look at with heart rate. An elevated or suppressed resting heart rate can be a sign of fatigue. Likewise an increase or decrease in your heart rate relative to your pace or running wattage can be another warning sign. 

• Heart rate responsiveness. Another heart-rate based indication of fatigue is that your heart rate becomes slower to respond to changes in intensity. So if you increase the effort level, you might find that your heart rate rises more slowly, and doesn’t climb as high as it usually would. When you reduce the effort, your heart rate might also be slower to return to a resting/baseline level. 

• Heart Rate Variability (HRV). This is a really popular monitoring method at the moment, now that wrist-based heart rate monitors are commonplace! HRV is the variation in the length of time between consecutive heart beats. HRV is more sensitive to stress than the other heart rate measures mentioned above. Every person will have a baseline HRV, which will differ from person to person and depending on the device you use to measure it. Many people believe it’s just a low HRV that’s bad. However, any deviation away from your norm (whether high or low) is actually potentially indicative of fatigue or general stress. It’s important to note that HRV measures are unreliable, especially if taken from the wrist, and personally I don’t set much store in these values. I certainly wouldn’t trust a HRV value as a main indicator of fatigue. I have countless examples where athletes I work with have bad HRV scores, but perform really well in training or racing.

• Running Watch Estimates. Many running watches have auto-generated indicators of fatigue, training status (e.g. ‘overtrained’) or estimated recovery time. These are also highly unreliable and I wouldn’t pay much attention to them!

Triangulating Values

In my view, the subjective indicators of fatigue (mood, motivation, sleep, the stairs test and RPE), are the most valuable and reliable indicators. All heart rate based measures can be sensitive to a whole host of other factors such as caffeine use, hydration, environmental temperature, time of day, and even body position. If you do want to use these heart rate measures, then I would use them as a secondary indicator to help support your subjective assessment. 

News

We have some new training plans available, focussing on preparation for mountain events of roughly 50-miles or 100km. These plans are perfect if you’re preparing for something like Lakeland 50, UTS 100, the CCC or any of the Bob Graham, Paddy Buckley or Ramsey Rounds. They focus on developing mountain-specific fitness, with a key focus on building up your tolerance for big days in the hills!

Click here to view these plans. Or if you’re interested in any of our other plans, you can check them out here.

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That’s it for this month! If you’re relatively new to the mailing list and want to see previous instalments, then you can do so here.

Thanks and happy running! 🏃‍♀️🏃

Emma