Scott Rayment – Podiatrist
Sudden increases in activity that exceed your body’s ability to cope and adapt are a major driver of running injury, and this can happen to any runner, at any experience level, not just beginners. These activity levels are commonly referred to as load, meaning frequency, duration, intensity and type of activity, whether that’s running, swimming, cycling or anything else. The tools below help you build load while minimising injury risk along the way.
Starting point: Couch to 5K
New to running or returning after a break, a structured, beginner-friendly program built around a goal of 5km is the safest way to progress. Couch to 5K (C25K) takes most people from no running background towards a continuous 5km over 9 weeks, using an interval format that gradually shifts the balance from walking towards running. We can talk you through a structured week-by-week plan if you’re starting from scratch.
The 10% rule
Reached your 5km goal, or already running and want to build volume safely, the 10% rule is well known in the running community for its simplicity, don’t increase your weekly training load (total kilometres per week) by more than 10%.
Example:
Week 1: 22km
Week 2: 24km (9.1% increase)
Week 3: 27km (12.5% increase)
Week 4: 30km (11.1% increase)
In this example, the jump from week 1 to week 2 is within a safe range. After that, the increases exceed 10% per week, which starts raising injury risk even though each individual week might feel manageable at the time.
Worth being upfront here, when this exact rule was tested head-to-head against a standard program in a randomised trial of novice runners, it didn’t significantly cut the number of injuries (Buist et al., 2008). It’s a useful rough guide for pacing your own progression, but it’s not foolproof, and it doesn’t replace attention to how your body’s actually responding.
Acute: Chronic workload ratio (ACWR)
For a more precise picture than the 10% rule offers, the acute: chronic workload ratio compares your acute workload, essentially recent fatigue, towards your chronic workload, underlying fitness, as a ratio. More involved to calculate, but gives more accurate insight into injury risk and training progression than a flat percentage rule.
Working out your ratio:
Calculate a 4-week rolling average in kilometres. Using the example above, that’s 22 + 24 + 27 + 30 = 103km ÷ 4 weeks = 25.8km per week on average.
Divide your current or planned week by this average to get your ratio. Week 5 at 30km ÷ 25.8km average = 1.2.
Interpreting the number (Gabbett, 2016):
Under 0.8: under-training
0.8 to 1.3: generally considered an optimal range
1.3 to 1.4: over-reaching
1.5 or higher: over-training
What these tools don’t do
Neither the 10% rule nor ACWR make you risk-free, they reduce risk by flagging when load’s climbing faster than your tissue is likely to adapt. Not a substitute for treatment if you’re already carrying an injury either, load management running alongside an unaddressed injury tends to just delay the same problem rather than settle it. Hard to say exactly how these numbers apply to you without knowing your history, injury history, foot type and footwear all interact with load in ways a generic percentage can’t fully capture.
Building a plan around you
These frameworks are useful starting points, but the runner in front of us always matters more than the formula. We can build a running program around your specific goals and injury history, factoring in things like previous stress fractures, tendon issues, or biomechanical patterns a generic 10% increase wouldn’t account for. Ask us about this at your next appointment, or book an assessment to discuss your concerns with us.
References
Gabbett TJ. The training-injury prevention paradox: should athletes be training smarter and harder? Br J Sports Med. 2016;50(5):273-280.
Buist I, Bredeweg SW, van Mechelen W, Lemmink KAPM, Pepping GJ, Diercks RL. No effect of a graded training program on the number of running-related injuries in novice runners: a randomised controlled trial. Am J Sports Med. 2008;36(1):33-39.