Most runners tend to run more and more and more, and end up running too far too quickly, all whilst going too fast. Whilst your lungs and mind may be able to handle the distance, your tendons, muscles and joints can often need more time to adapt. Building up an endurance for running takes time and jumping into a half marathon from a 5kms in 4 weeks is not the way to avoid overuse injuries.

In strength and conditioning, ‘progressive overload’ is a concept that involves gradually increasing the stress or demand placed on the body over time. Building your running base over a longer period helps the body adapt and become used to the stress of running. Increasing your weekly milage can be difficult as people are unsure of when to increase and by how much. Getting a running program from a qualified running coach can help with this and allow you to stick to a plan that will progressively overload towards your goal.

Alternatively, many people reference the ‘10% rule’ (also known as the "Acute Running Ratio"). Using the 10% rule as a guideline, runners aim to progress their distance by 10% each run or each week (for example, the distance ran may increase from 5km the previous week to 5.5km). The 10% rule works extremely well for beginner and intermediate runners. As you become more adept, the 10% rule quickly becomes obsolete.

What is the Acute Running Ratio?

Once you begin to accumulate higher running volume, increasing your distance by 10% each week can be dangerous. This is where the acute:chronic workload ratio can come into play. The acute load refers to the training volume over one week, and the chronic load is the average training volume over the preceding four-week period.

The formula is simple – acute workload divided by chronic workload = acute:chronic workload ratio.

For example, somebody regularly running 5-10kms every week decides to run 15km.

- Week 1 (5km) + Week 2 (8km) + Week 3 (7km) + Week 4 (10km)

- 4-week average = 7.5km

- 15 / 7.5 = ~ 2.6

Studies show keeping this ratio between 0.8 and 1.2 tends to be the sweet spot for most people. Under 0.8 and you may be ‘de-training’ or ‘deconditioning’ without adequate stimulus for your system, and over 1.3 can significantly increase your risk of becoming injured.

So whatever method you pick, the idea is to ensure you’re not progressing faster than you should and that a good running plan helps keep you on track from falling for this common pitfall.