Efficiency Factor Explained: What It Is, Why It Matters, and How to Improve It After 40

You can’t feel it when you're cycling, which is why a lot of cyclists I work with have no idea whether they're efficient or not.
They're training consistently, putting in effort but maybe not seeing results as quickly as they would like. Often, it’s down to a number they’ve never looked at, their efficiency factor, one of the most useful and most overlooked performance metrics available to cyclists over 40.

What is Efficiency Factor

Efficiency factor is simple. Take your average power from a steady aerobic effort (ideally zone 2) and divide it by your average heart rate from the same ride. ‍

Average power ÷ Average heart rate = Efficiency factor

So if you averaged 160 watts at an average heart rate of 140 beats per minute, your efficiency factor is 1.14. What that tells you is how much power your cardiovascular system is producing per heartbeat. A higher number means your engine is running more efficiently, producing more power for the same effort. A lower number means your heart is working harder than it should to produce that power.

For cyclists over 40, this matters more than you might think. As your aerobic engine becomes more efficient, you produce more power at lower heart rates, recover faster between sessions and hold your effort for longer before fatigue sets in.  

What Is a Good Efficiency Factor for Cyclists Over 40

From working with 100s of cyclists, a reasonable starting point for a well-trained 40+ year old is an efficiency factor between 1.3 and 1.7. Where you sit in that range depends on your training history, current fitness, and how consistently you've been building aerobic base.  

Between 0.9 and 1.4 is a zone where most uncoached amateur cyclists sit when they first start tracking this.

Below 1.2 on a zone 2 effort suggests your aerobic engine is working considerably harder than it should be at that intensity. This is something I see a lot in cyclists who’ve spent years training at moderate to high intensities without building a proper base.

Above 1.5 indicates good aerobic development. Your engine is running efficiently at sustainable intensities, which means quality, focused base building sessions produce more adaptation, and recovery between them is faster.

Above 1.7 is where well-trained endurance athletes tend to operate. Achievable for 40+ cyclists with a strong aerobic base and a consistent, focused training history.

Why You May Have A Lower Efficiency Than Expected

This is where it catches cyclists out.

I’ve worked with clients who’ve been riding for fifteen years and still have a lower efficiency factor than someone who’s been riding for three, but trained with structure. Experience without structure builds fitness, but not efficiency. Years of moderate intensity cycling  gets you used to putting in the effort, but doesn’t  teach your body to produce power economically. The engine’s been used a lot. It just hasn’t been trained to run efficiently.

After 40 this matters more.

You can still improve, but the body responds better to the right kind of training and is less forgiving to the wrong kind. If you keep cycling in that middle ground the return starts to decline. The good news is it does respond quickly when you get it right. Cyclists in their forties, fifties and even sixties often see clear improvements in efficiency within 8 to 12 weeks of consistent, structured aerobic work.

Aerobic Decoupling. The Related Number Worth Knowing

Alongside efficiency factor, there is also something called aerobic decoupling. This gives you a second useful number to track. Decoupling measures how much your heart rate drifts upward relative to your power output over the course of a long steady effort. On a well-paced zone 2 effort, both should stay relatively stable. If your heart rate keeps drifting up while power stays the same, or you have to reduce power to control it, that’s decoupling. This is a sign your aerobic system is fatiguing sooner than it should.

As a guide, below 5% on a longer zone 2 ride is generally considered a sign of good aerobic fitness. Above that, there’s work to do. We’ll go deeper into this in another blog, but for now, just know this:

Efficiency factor and decoupling are telling you the same story from different angles.

How to Start Tracking Your Own Efficiency Factor

You don't need expensive or complicated software to do this.  The calculation is straightforward and can be done with any ride that includes both power and heart rate data.

Pick a genuinely steady zone 2 ride, ideally indoors as it’s a more controlled environment so produces a more consistent effort for at least 45 – 60 minutes. This is important. The number is only meaningful on a controlled effort. A club ride, a commute, or anything with significant variability will produce a distorted number.

After the ride, find your average power and average heart rate for the main steady portion of the effort, excluding cool-down. Divide average power by average heart rate. That's your baseline efficiency factor.

‍
Track it monthly on the same type of effort. The trend over time is what matters more than any single number. Consistent improvement across a 4-12 week training block is confirmation that your aerobic base is improving. A plateau or decline signals that your training structure needs adjusting.

EF can also be worth tracking year on year at the same event. If you ride the same sportive or the same long route in similar conditions with similar fuelling and a similar approach, comparing your EF across years tells you if you are producing more power for the same cardiovascular cost over a long ride.

Treat it as a broad signal rather than a precision metric, as too many variables affect a long outdoor ride to make the comparison exact. But a meaningfully higher EF at the same event a year later, under similar conditions, is genuine evidence of aerobic development and progress.

How to Improve Your Cycling Efficiency Factor

The training that improves your efficiency factor is the same training that most cyclists skip: consistent, well-paced zone 2 cycling.

Zone 2 is where you can hold a full conversation easily, where heart rate is stable, and your power is consistent and controlled. For most cyclists this feels almost too easy when done correctly. At this intensity the body preferentially develops the parts of your aerobic system that make you more efficient. The adaptations are slow and cumulative and don't arrive after a single block of training but compound over months. This produces measurable, lasting improvement in your efficiency factor.

Eight to twelve weeks of two to four genuine zone 2 sessions per week, alongside well-structured quality work, typically produces a visible EF improvement for cyclists who have been training predominantly at moderate intensity.

The reason zone 2 work produces this improvement comes down to mitochondria, the energy-producing structures in muscle cells. Think of them as firelighters in a barbecue. More of them means the flame ignites faster, burns brighter, and stays alight longer when the effort demands it.

Consistent zone 2 training progressively increases mitochondrial density. Over time this produces a specific and measurable adaptation: cyclists find they can sustain higher power outputs at the same heart rate. Power that was once zone 3 effort starts sitting at zone 2 heart rate. The engine is running more economically at higher outputs.

This is exactly what happened with two riders I've coached over extended periods. Will dropped his average heart rate by more than ten beats per minute on zone 2 rides through structured training. Luke progressed from an efficiency factor of around 1.4 when we started working together to consistently above 1.8, with some rides touching 2.0, which is genuinely pro-level aerobic efficiency. Both improvements came from the same source: a deliberate, patient investment in aerobic base before the harder training phases were introduced.

The mitochondrial density built at the base also pays dividends higher up the training pyramid. Riders with a strong aerobic foundation recover faster between hard intervals, handle accumulated fatigue better across a training block, and hold their form later into long events. The base work looks unimpressive at the time but what it enables later is significant.

Efficiency factor won't show up on your Strava feed or impress anyone at the café stop but it’s one of the clearest indicators of whether your training is actually working. If you’ve never looked at it before, the first number you get will tell you how well your engine is really working.  Once you know this, it will change how you train.
That’s exactly what we focus on inside Elevate. We take the training you’re already doing and build a structure around it, so your fitness starts to improve consistently, instead of plateauing. If you want to understand what your own data is actually telling you, and how to improve it, book a free coach call.
‍
→ Learn more about Elevate

‍