How Runna Can—And Should—Fix It’s Algorithm’s Age Bias Issue

Runna has continually impressed me on just about every front since they first appeared—and started their exponential growth—at the tail end of the pandemic.

The platform was genuinely impressive from the very beginning. It took a ubiquitous concept and seemingly did everything the right way: investing heavily in UX, doing industry-leading influencer marketing campaigns, making the leap into the US market and, of course, courting and then landing an acquisition by Strava. It feels like the London-based startup has barely put a foot wrong.

Along with the social media buzz, the merch, the events, Runna is providing undeniable value to the running market: bringing informed, adaptive training plans to the masses, and at a more affordable price point than a traditional running coach.

While I don’t think an app can entirely replace a human coach in terms of effectiveness (at least for the foreseeable future), the idea of rolling up all commonly-accepted training wisdom into an adaptive mobile platform definitely creates a new option for those who either can’t afford or aren’t ready for a coach, and it also provides a great on-ramp for new runners to get started in a structured way.

For now, Runna’s algorithm has its obvious weaknesses. It can’t measure your willpower on a given day, know your mood, intuit if you’ve had a great or terrible night’s sleep, know how serious your marathon goal is to you, and so on. Instead, it takes in all the data it can—a battery of responses you give it when you sign up, plus data from each of your runs—to create a training plan around your goals.

Which is why it was so surprising to learn that Runna’s algorithm doesn’t account for a runner’s age.

And, I get it.

Runna has been marketing directly at Gen Z, focusing heavily on Instagram and TikTok. They know their target demographic and they’ve completely nailed it. Run clubs. Tinder collabs. Influencer campaigns. They’ve built their adaptive training plan algorithms around young people who are at their physical peak, and don’t have to worry about some of the issues that older runners have to account for.

But, now that Runna is essentially the go-to run training app, they’ve got a responsibility to ensure their app works for every runner, regardless of age.

The Runna Age Input Experience

I’ve noodled with Runna a decent amount over the last couple of years, often frankly to marvel at how nice and slick it all is.

When you first register on the app, unsurprisingly, you’re prompted to enter your date of birth along with other data. The app even states that “your age will help us personalise your training intensity and reduce injury risk.” So far, so good.

But it turns out, this data isn’t currently used by the algorithm, it seems.

On a discussion from May 30 on the Runna subreddit, a user flagged that the date of birth and gender prompts were new. To which a Runna team member (sarah-runna) replied, explaining that they’ve recently started including the date of birth prompt, and that “in the future we might start using it to make our plan engine even more personalised to you”.

The Runna staffer goes on to say: “one example is that we often get feedback that Runna plans aren’t always doable for 50-60+ users, so if we had this data we could look to make changes specifically for them“.

I had to read those lines a couple of times to let them sink in.

Seriously?

The biggest running app in the world, with millions of users¹, treats a new-to-running 68-year-old the same as an 18-year-old?

Hold up.

Over on LinkedIn, there are 166 people listed as being on the Runna team—with 39 of them dedicated to engineering. Now those numbers aren’t exact, but the point is that Runna have the resources to figure this out and provide older runners the same quality, injury-free experience as its target demographic.

As far as I can tell, Runna generates your initial plan based on recent race results (if you have any) and your self-described running level. Age is not accounted for.

On that Reddit thread, there’s a 68-year-old runner who acknowledges moving to a different plan from Runna following an injury.

Yes, Older Runners’ Bodies Are Different

I don’t think I need to convince anyone of this point, do I? We all lose lean muscle mass as we age; we all take longer to recover after workouts; we all take injuries harder and take longer to bounce back.

A 60-year-old doesn’t bounce back from a calf strain like a 30-year-old does.

If my granny knows this, Runna should too.

How Coaches Account For Runner’s Ages

Our own head coach, Katelyn Tocci, weighed in on the importance of accounting for age:

“As a running coach, considering an athlete’s age is crucial because it directly affects recovery time, injury risk, hormonal shifts, muscle mass, and aerobic capacity.

A 25-year-old and a 55-year-old can both be strong runners, but their bodies can respond differently to stress, volume, and intensity.

For younger athletes, I might include more speed work and shorter recovery periods in their training plans, as they can often bounce back from repetitive stress more easily than an older runner.

In contrast, for older athletes, I prioritize longer warm-ups, more recovery days, lower-impact workouts such as cross training, and strength training to preserve muscle mass and joint health. As we age we naturally lose muscle mass (sarcopenia) over time, so strength training becomes even more essential for performance and injury prevention.“

Raziq Rauf (Raz), USATF-certified running coach since 2018, and author of Running Sucks, told me:

“There’s a reason 40+ is the masters category. Bodies can do less as they age. Slower recovery, reduced strength, more chance of injury, lower VO2 max, and so much more just happens naturally, so it’s crazy that Runna hasn’t taken age into account before. 

Of course there are so many factors involved, but you generally have to dial down the intensity of the workouts for older athletes. You might add more strength training and more rest, for instance. As a coach, it’s difficult to give too many generalizations in good faith.“

Rauf told me that he’s extra-cautious when it comes to advising older runners, even turning down clients that he’s not confident in coaching.

How Runna Can Fix Its Age Bias

The following are a grab-bag of quick wins that Runna could incorporate into it’s algorithm that would immediately improve the experience and reduce injury risk for it’s older users.

None of these are exact, or perfect, but since we’re starting with a blank slate it’s not hard to make some major improvements:

1. Age-Appropriate Mileage Progression Rates

• Why: Older runners often experience slower adaptations.
• How: Use more conservative mileage or intensity increases.

2. Age-Adjusted Ratio of High-Intensity to Easy Workouts

• Why: Hard intervals carry a higher injury risk as runners age.
• How: Lower the frequency of interval or sprint sessions, or replace some intervals with threshold or steady-state runs.

3. Longer Warm-Ups and Cool-Downs

• Why: Joint and muscle elasticity decrease with age, making dynamic warm-ups crucial.
• How: Extend warm-ups and cool-downs by 5–10 minutes, focusing on mobility and dynamic stretching.

4. Strength and Mobility Work Emphasis

Many younger runners can get away with practically no strength training; older runners will suffer sacropenia (muscle mass loss) and decreases in bone density without it, so it should be a mandatory recommendation for older runners.

• Why: Strength and flexibility decrease with age but are vital for injury prevention and performance.
• How: Increase weekly strength and mobility-focused sessions (e.g., yoga, bodyweight work).

5. The Precautionary Approach – Frequent Check-Ins and Nudges To Go Easy

• Why: The implications of a festering injury to an older runner are much more drastic than that of a younger runner: they can be derailed for months, and lose a lot of their fitness, due to overlooking an injury.
• How: More frequent checking in with the older athlete, and nudging them to rest or downgrade an upcoming workout if they’re feeling any signs of fatigue or injury.

Runna Is The Leading Running App. Now They Need To Account For All Runners

At the risk of repeating myself, what Runna has achieved is outstanding.

They’ve got an incredible number of people into running and helped many more achieve impressive running goals.

And now, they’re in the position of being the dominant running app.

With this position, I’d argue they’ve got a public responsibility to not just serve runners under 40, but to make a product that serves anyone who picks it up.

Older runners have more to lose than younger runners: injuries through improper training can set them back months, during which time they can lose crucial fitness that they may never fully regain.

I’m looking forward to seeing Runna resolve this and help even more people with their running goals.

1. https://public.runna.com/ ↩︎