Why Does Running Feel So Hard When I'm Going So Slow?

Have you ever gone out for an easy run and looked down at your watch only to wonder why your heart rate is so high when you feel like you are barely moving? You might be trying to stay in Zone 2, but no matter how slowly you run, your heart rate keeps climbing and climbing. What about when you’re running with a friend who can carry on an entire conversation while you’re struggling to get a a word out.

Why does running sometimes feel so hard when you’re going so slow?

The first thing I want to talk about is that pace and effort are not the same thing.

Your body doesn't know what pace you're running

Well, sort of. Your body responds to the physiological demands of running, not the number on your watch.

A 12-minute mile might be incredibly easy for one runner and a challenging effort for another. Your cardiovascular fitness, muscular endurance, running economy and training history all influence how hard a particular pace feels.

Running economy refers to how much energy your body uses to run at a given speed. Research shows that running economy is influenced by many things, including biomechanics, neuromuscular coordination, muscle and tendon function, and metabolic efficiency. So two runners can have similar aerobic fitness but use different amounts of energy to maintain the same pace.

But, running economy and aerobic fitness can improve with training.

Why is my heart rate so high when I'm running slowly?

There's been a lot of discussion about Zone 2 training lately. While training at lower intensities has benefits, I think we've made it unnecessarily complicated for many runners. Your heart rate is influenced by more than your fitness. Heat, humidity, dehydration, stress, sleep and accumulated training fatigue can all affect how your body responds to a run. Heart rate zones calculated by your watch are also estimates. They don't necessarily reflect your individual physiological thresholds.

Oe of the things I ask my athletes to do to assess their running intensity is the talk test. Can you speak in complete sentences without becoming short of breath? Research supports the talk test as a easy and practical way to monitor exercise intensity.

And if you need to alternate walking and running to maintain an easy effort, that's perfectly fine.

Sometimes running feels hard because your body is working harder

There's another important question I ask my athletes - has running always felt difficult at this pace, or has something changed?

If you're new to running, your cardiovascular and muscular systems are still adapting. With consistent training, the same pace will often require less effort. But if you've been running comfortably for months and suddenly your usual easy pace feels exhausting, I'd want to know why.

Are you recovering adequately?

Eating enough?

Sleeping well?

Have you recently increased your training?

On Episode 30 of our podcast, The Running Injury Podcast we discussed a 13-year-old runner whose performance was declining despite continued training. We explored how inadequate fueling and recovery can affect performance. Even though this episode is about a 13- year old the concepts hold true to all age groups.

Low energy availability can impair training adaptations and athletic performance, something highlighted in the International Olympic Committee's 2023 consensus statement on Relative Energy Deficiency in Sport.

Athletes with persistent or unexplained declines in exercise tolerance should undergo further evaluation.

So how do you make running feel easier?

My advice is pretty simple. Stop comparing your easy pace to someone else's.

Run at an effort that matches your current fitness.

Walk when you need to.

Build your training gradually, incorporate strength training, eat enough to support your activity and allow yourself time to recover.

Pay attention to how running feels over several weeks rather than judging your fitness by one run.

Easy running is relative. As your body adapts, what feels difficult today may eventually become your comfortable pace.

You might even find yourself enjoying those slower runs a little more.

References

1. Saunders PU, Pyne DB, Telford RD, Hawley JA. Factors affecting running economy in trained distance runners. Sports Med. 2004;34(7):465-485. doi:10.2165/00007256-200434070-00005

2. Reed JL, Pipe AL. The talk test: a useful tool for prescribing and monitoring exercise intensity. Curr Opin Cardiol. 2014;29(5):475-480. doi:10.1097/HCO.0000000000000097

3. Mountjoy M, Ackerman KE, Bailey DM, et al. 2023 International Olympic Committee's (IOC) consensus statement on Relative Energy Deficiency in Sport (REDs). Br J Sports Med. 2023;57(17):1073-1097. doi:10.1136/bjsports-2023-106994