What's your heart rate?

I run a lot, and when I do I wear a sports watch (a Garmin Forerunner 945 for those who were wondering).

For years it showed me all sorts of stats like speed, distance, vertical metres, pace, and so on.

But I've set it up so now it only shows me one thing, my heart rate.

That's because over the years I've worked out that this is the one number that actually tells me something useful that I can react to. Depending on the run, if it (my heart rate) is too high then I slow down and if it's too low I speed up. Speed (e.g. you are running at 10km an hour) or pace (e.g. you are running 5 minute per km) aren't useful in the same way. A pace that's manageable on the flat or on the road might be impossible to sustain going uphill or on a rocky trail. Distance doesn't tell me much either, and neither does time.

Some people don't like using heart rate, they say it's a 'lagging measure'. But I like it because its 'directionality' tells you something useful too. If your heart rate was too high, and you've reduced your effort then it should start to come down, if it doesn't then you need to reduce your effort further.

Heart rate is also affected by factors like heat, fatigue, hills and how well I slept, and that is exactly why I like it. Every one of those things changes how a run actually feels.

The Hidden Cost research I did earlier this year suggests that digital work has a similar problem - that there doesn't seem to be an accurate way of measuring effort (and making that effort legible to the wider organisation). There's no clear, reliable, or visible way for digital practitioners or teams to track how close they might be to tipping into overwork. Often the overload is only noticed after it happens, which isn't good for anyone.

I've written previously about NASA's Task Load Index (NASA-TLX), which measures how demanding work feels to the person doing it. It asks people to rate a task across six dimensions:

• Mental demand (how much thinking it requires)
• Physical demand (how much physical effort is needed)
• Time pressure (how rushed it feels)
• Effort (how hard you have to work to get it done)
• Performance (how successful you feel you were)
• Frustration (how stressful or irritating it felt)

Whilst something this involved is maybe overkill (and frankly unworkable) for a lot of digital work, I do wonder what the most useful number (or numbers) might be for understanding the velocity and capacity of it. Or whether they even exist.

How do you know when you're getting close to the edge? And how do you know when you could push a little harder? I know that once my heart rate goes above a certain number then things start to feel more difficult, though I can probably sustain it for a while. But over another number (about 170 at the moment), that my effort can't be held for long (and I usually start to feel a bit sick).

When implementing the EOS management system there's a real focus at a leadership level on 'leading' (forward-looking) indicators which are the numbers that tell you something is about to go wrong while there's still time to do something about it. What makes them work is that there is a threshold attached to each one, with specific actions that are triggered when you cross it. E.g. if we're not having at least four new business conversations a week, that isn't something to wait and discuss at the quarterly review, it's something we will act on now, in these specific ways.

Google does something similar with what it calls 'toil' which they define as the manual, repetitive work that keeps a service running but doesn't improve it. Its engineering teams try to make sure that toil doesn't occupy any more than 50% of anyone's time, and if the proportion of their time spent on that type of work goes above that threshold then they do something about it.

The thresholds I can think of are nearly all aimed at outputs (hours worked, sales conversations, delivery dates, uptime). Fewer are aimed at understanding whether the people doing the work can keep doing it. My heart rate is this second kind of number - it tells me something about me, not about how fast I'm going.

So what's the version of that for a digital team? Which number(s) would tell you a person or a team is heading for overwork while there's still room to ease off?

It's going to be a tricky question to answer well, but it feels worth a conversation.

Here are a few ideas I've had about what an approach to this might look like (none of them are perfect), curious to hear what you think:

• Self-rated strain, tracked every week. Ask your team one question, scored 1 to 10 - “how sustainable was this week’s workload?” The trigger for action might be when you spot two consecutive weeks which are scored at 8 or above, or a rise of, say, three points against the person’s own baseline. The action could be a scheduled conversation about that individual's workload within x days. The weakness of this approach is that people are likely to under-report how they feel in cultures where admitting strain feels risky and people have to believe that accurately reporting how they feel will result in a meaningful intervention.
• Recovery time gap. Track the days since the last stretch of at least, say two or three hours, of protected/deep work time (i.e. with no meetings and no reactive work). The trigger could be if that gap stretches to more than five working days. The weakness here is it only measures what's in your calendar not the reality of your days (reactive work rarely arrives as a calendar invite!) and some people thrive on fragmented days so this wouldn't necessarily link to how overloaded someone felt.
• Proportion of unplanned work. Track the proportion of the week spent on work that was not planned on Monday. The trigger would be whenever the % rises above a team-agreed percentage. The weakness here is that unplanned/undefined work is also difficult to track, and this approach would rely on people recording how they've spent all their time which is...notoriously difficult/problematic (and is also additional work).
• Personal early-warning behaviour. Get each person to identify their own 'tell' (e.g. skipping lunch, short replies, stopping taking leave) and track whether they notice it in themselves. The trigger here would be that the person sees the behaviour appear. The action would be that they flag it to the team and agree an intervention. Although people may not notice their own 'tells' until it's too late, and identifying and sharing them requires a high level of trust.

There probably also needs to be a 'directionality test' around whatever you try i.e. after the amount, type, or scope of work is reduced, does the strain score (whatever you might be using) fall within a specific amount of time, e.g. two weeks? If not, the cause of the 'strain' probably isn't the work itself, and easing things further is likely to be the wrong intervention. In these cases attention may then need to turn to other elements such as whether the role suits the person, and the general working environment. This includes the culture (e.g. what gets rewarded, how available people are expected to be, whether it feels safe to admit they are feeling under strain) and any wider pressures the organisation itself may be under.

I expect that any progress in this area will only emerge from experimentation, and what works for one team may not be transferable. But I'm keen to hear what others think, or have experienced.