What’s better: a long, slow run or a short, fast one?

Unless you’re following a dedicated training plan, it can be hard to tell when you should speed things up and slow things down, let alone how far you should be running in the first place.

There’s a reason why slow running gets so much attention: it’s incredibly beneficial, no matter what stage of your running journey you’re at.

Taking a run ‘easy’ is valuable because its a great way to build your endurance and improve your fitness without causing as much stress on the body as running faster.

Long, slow runs are particularly effective for people looking to increase the distance they can run for because low-intensity or ‘zone two’ training can improve your lactate threshold. This is important because increasing your lactate threshold allows you to run faster and further using anaerobic energy - your body’s low-intensity, endurance energy source.

Doing less intense cardio work can also help to improve muscular and aerobic endurance because of the way it improves oxygen flow. It’s also particularly effective at capillarisation, the process of increasing the number of capillaries that serve a muscle and thus improve your muscular and aerobic endurance by delivering oxygen to that area of the body.

But while running fast all the time isn’t good for you, there are plenty of benefits to incorporating speed work into a routine too.

Short, fast runs are a great way to challenge both your heart and lungs as well as your muscles and adding ‘fast’ runs into your weekly schedule is important if you want to get quicker.

But they’re often underestimated for their effectiveness in burning calories. Short, regular runs can also reduce your risk of developing heart disease - and of course they’re easier to fit into a busy schedule.

In general fitness terms, around 80% of your runs should be long and slow, and 20% should be short and fast.

Your goals and current strengths and weaknesses will help to what you should prioritise in your training. For example, if you’re training for a marathon or beyond, you should prioritise long, slow runs. If you want to run quicker over the 5k distance, then you should prioritise short, fast runs.