What’s a good and average 5k time for my age?

Five kilometres, just over 3.1 miles, is running’s primary gateway distance. It tends to be most people’s first exposure to the sport, be it a parkrun or Turkey Trot, but it’s also a distance that many runners spend a long time trying to get right.

This might lead you to take a look at your own 5k time and think, is it good? This is multifactorial, a good 5k is dependent on your age, gender and athletic history – much of this is to do with how these characteristics impact your VO2 max.

On top of this, there’s environmental considerations at play – are you doing your 5k in a triathlon and what is the temperature and humidity? 

What is a good 5k time? 

Generally speaking, parkrun is the place to go for this information. Interestingly, the nation’s pace at parkrun has slowed over the years — a trend with positive implications as it means a broader range of people are taking up a Saturday morning 5k.

Over 16 years, the average finish time has increased consistently. In 2005, the average time stood at 22 minutes and 17 seconds, compared to 32 minutes and 30 seconds in 2020. 

That said, a good 5k time is different depending on your personal circumstances – primarily your age and gender. We will go ahead now and break that down further. 

What is a good 5k time for your age?

Your 5k time is heavily dependent (but not entirely) on your VO2 max which conventional academic wisdom dictates that it decreases approximately 10% every decade past the age of 30. This decline can be reduced with training. 

The graph above shows the male and female age graded 5k world records. Interestingly, the linear decline observed in science of VO2 max with age is quite visible with the times slowing down as a straight line from the age of 50 to 75 before a sharp increase.

After the age of 75, the population of possible runners decreases quickly and, as a result, the rate of speed decrease ramps up. 

This graph is how age graded times work. Age grading has been around for many years and was popularised in the UK by parkrun. The way it’s calculated is to divide your age group world record by the time that you achieved.

For example, a 50 year old male who runs a 22-minute 5k would have an age graded score of 15 divided by 22 which is 68.2%, we can then calculate an equivalent time by multiplying the percentage with the open world record and we get a time of 18:27.

The result of this means that a 50-year-old male running 22 minutes would be equivalent (using this method) to a 30-year-old running 18:27. 

The graph above shows that according to age grading methodologies, the times on a given curve are equivalent. The graph above shows the equivalent times for a person under the age of 35 running 15, 20 and 25 minutes. For example, a male running 15 minutes at age 30 will be equivalent to a 60 year old running 20 minutes. 

There’s an infinite number of graphs we could make here but the way to calculate your equivalent time is as follows. 

Step 1: Divide the open world record for the appropriate sex by the time in mind.

Step 2: Divide that number (which should be less than 1 unless you’re planning on setting a world record) by the world record for the appropriate age. 

For example, if we want to know what the equivalent time for 20 minutes for a 60 year old female would be we do 14 divided by 20 which is 0.7. We then divide the female 60 year old 5k record by 0.7 which gives us an age equivalent time of about 27:14. 

How fast should I run 5k in a triathlon?

If you’ve ever run in a triathlon, you’ve probably noticed it’s a bit harder than running during an open race and that you go a little slower. Your running ability in a triathlon is highly dependent on how tired you are when you get off the bike.

Science has looked into this. Several studies have compared running performance in triathlons with standalone running events and their finding breaks down into the following:

Biomechanical changes

A study in the BMJ examined biomechanical changes in running gait during triathlons. It found that triathletes exhibit alterations in running biomechanics, such as changes in stride length and frequency, compared to when they run fresh. They did say that more work needs to be done into the extent of triathlon impacting run speed. 

Heat and hydration

Environmental factors, such as heat and hydration status, can further impact running performance in a triathlon compared to standalone running events. In long-course triathlons, heat accumulation is a problem and athletes’ core temperature can get very high before they start running. In contrast, athletes doing a standalone running event in the same conditions will start with a much more ‘normal’ core temperature. 

While these studies provide valuable insights into the differences between running in a triathlon and running fresh there are also individual variations among athletes and the specific demands of different triathlon courses and race dynamics.

Studies have also shown that it’s harder to run off a bike with high stochasticity – meaning a smooth bike leg vs a bike leg with a lot of surging is easier to run off.

This is seen with hilly races even in middle distances, where run times are often slower even when average power is actually lower than a race which is flatter.  

How to estimate my 5k time?

If you’re fortunate enough to own a smart GPS-watch of some type you’ll likely be aware of its tendency to guess your race ability over various distances. This is essentially done by curve fitting using the ‘Critical Speed’ or ‘Critical Power’ model of running. 

Here’s how it works:

•  Critical Speed: Critical speed is the maximum speed at which an athlete can run aerobically without accumulating an excessive amount of lactate in the blood, which leads to fatigue. It represents the boundary between steady state running and an unsustainable effort. This is the running equivalent of your Functional Threshold Power, or FTP. 

• Relationship with Distance: The critical speed model suggests that an athlete can sustain this pace for a certain duration, depending on the distance being covered. For instance, an athlete can maintain critical speed for about 20 to 30 minutes. This can be used to calculate possible sustainable paces for given durations. 

• Fatigue: Running faster than the critical speed will lead to the accumulation of lactate and metabolites associated with fatigue. 

Estimating your pace for a 5k should be done with the critical speed model. There are many calculators online to aid athletes doing this. 

Conclusion 

In conclusion, a good 5k time is influenced by various factors such as age, gender, athletic history, and the demands of different race formats as well as conditions on the day.

Understanding what constitutes a good 5k time on a given day requires a nuanced approach whereby the runner in question considers all factors at play. 

Parkrun serves as an invaluable resource for benchmarking 5k performance, showcasing a diverse range of participants and their evolving pace over time.

Age grading offers further insight into individual achievements by comparing performances across age groups, revealing how age impacts running capabilities and highlighting the potential for improvement through training. We know that as we age, our VO2 max decreases linearly and 5k time seems to increase accordingly. 

Triathletes face unique challenges when it comes to running off the bike, with biomechanical changes and environmental factors affecting performance.

The stochasticity of the bike, as well as how close you’re riding to your capacity, will dictate how close a triathlete is able to perform relative to their open running abilities. 

Strategies for estimating 5k times often rely on models like critical speed, which offer a scientific approach to predicting sustainable paces based on physiological parameters. These have wide errors though and runners should be wary of being limited by what their watch suggests they can achieve. 

Ultimately, the pursuit of a good 5k time is extremely individual and your personal circumstances will dictate what makes a ‘good’ 5k time.