Updated: Mar 27, 2021
Running fast is great. It’s impressive on Strava, Nike Run and at Races, you get Personal Bests, you look better to the people around you and you get to pass people. Why wouldn’t you want to run fast? It's better than running slow in every way, right?
Not so fast. The pace at which you run is a tool. If you think of speed as a spectrum from slow to fast, every notch between the endpoints has different advantages. It’s easy to see the pros for running fast, but what is the trade off. Remember that speed is a range from slow to fast and to the degree that you get faster the pros and cons become more impactful. So know what you're giving up when you go faster and know what you gain when you go slower.
Pros and Cons of Fast and Slow
I like to think in terms of analogues, so let's think about doing lunges for 60 seconds. What happens when you go fast is you:
Increase the number of lunges you do in the time frame,
Increase your likelihood of falling over, it becomes harder to practice great form the faster you go,
Breathe faster which means you increase your effort and HR, and
Burn (slightly) more energy (your weight stays the same, but your speed increases).
So what happens when you go slow for the 60 seconds is you:
Do a lower number of lunges,
Are more stable (although at an extreme slow you become unstable again),
Maintain moderate breathing,
Burn less energy,
Are able to be more mindful of the exercise, noticing micromovements and aches and pains as they come up,
Are able to adjust your core mid-movement with less fear of falling,
Have more mental capacity or focus for form, as it is not being taken away by speed,