Stay tuned for the next article – a 12-week training program to improve your kJ endurance!

Why 3,000 kJ is gaining attention…

News is in that 3,000 kilojoules (kJ) — the total energy expended on the bike during a ride — may be a useful benchmark for serious or aspiring cyclists – and to anyone who has raced, it’s barely news at all…

According to coaches at Red‑Bull‑Bora‑Hansgrohe’s Under-23 development program, riders who can still produce strong power outputs after expending ~3,000 kJ demonstrate a level of durability and endurance that could translate to race-level performance.

In professional races, total energy expenditure is often much higher — often a top pro rider’s performance under fatigue comes after 5,000 kJ or more.

The upshot: if you’re a committed amateur or developing rider, then ‘training for kJ’ — building your capacity to perform even when tired — can be a powerful complement to traditional power / VO₂max / FTP metrics.

To any decent coach or indeed elite amateur upwards, this is not news – because if you re training to win races, you are essentially training specifically to be able to pull your best shot at the end of the race.

I tell my athletes often – When you think you are done, you are not done – it’s this area of the session or race that is crucial to improving, near the end, when you are tiring – and in a nutshell, this simple concept needs to be grasped to make serious improvements – and yes, it hurts…

What tracking kilojoules reveals — beyond “just power output”

Power meters and heart-rate monitors remain indispensable, but focusing on total work done (kJ) adds a layer of realism: real rides and races aren’t all about all-out four-minute efforts — many depend on sustained output over hours.

By tracking how your power output degrades (or holds up) over a high cumulative workload, you can gauge durability — that is, how well your engine copes when the tank is near empty. Here’s a simple test:

• On a rested day: warm up, then do a 20-minute maximal time-trial effort; record average power.
• On another day, ride steady (zone 2–3) until your head unit shows 2,000–2,500 kJ (for well-trained amateurs, 2,500 kJ; less fit riders may hit it sooner). Then spin easy 5–10 min, and — without pre-warmup — do another 20-minute max effort.

If your 20-minute power drops by 5% or less between fresh and fatigued efforts → you’re “very durable.”
A drop of 5–10% → moderate durability.
A drop of >10% → signals you might need to improve endurance.

That’s a concrete, measurable way to track more than just “peak watts” — instead, you test your ability to deliver sustained performance under fatigue.

Training to raise your kJ ceiling and endurance

So — how do you actually raise your capacity to produce power even late into a long ride? There’s no magic formula, but these training principles and practices tend to deliver.

• Build aerobic base via Zone-2 / endurance rides

One of the best foundations for long-lasting performance is to spend time in low-to-moderate intensity, high-volume rides. Riding in Zone 2 (roughly 60–75% of your FTP, or 60–70% of max heart rate) helps build aerobic capacity, mitochondrial density, and fuel-efficiency.

For many riders, gradually extending weekend rides — say from 1 hour → 2, 3, even 4+ hours (when schedule permits) — builds the engine.

• Add structured intervals: tempo, sweet-spot, VO₂max, anaerobic or sprint

Pure endurance isn’t enough if you want to hold strong power late into a ride or respond to surges. That’s why mixing in higher-intensity workouts is important:

• Sweet-spot or tempo intervals — efforts at ~76–90% of FTP (or just under threshold), such as 10–20 min blocks, help train your body to sustain a hard but manageable pace.
• VO₂max intervals (e.g. 3–5 minute hard efforts) expand aerobic capacity.
• Anaerobic / sprint intervals help build power for surges, attacks, climbs, and race-winning efforts. For example: 1-minute efforts at 130–160% of threshold power with ample recovery.

Combining these with endurance rides yields a more complete engine — one that can produce power across a range of durations and fatigue levels.

• Train for fatigue — long rides with efforts late

Build fatigue resistance by structuring long rides with intensity at the end — e.g. several hours steady ride followed by a few hard efforts.

This adapts your body and mind to handle the most demanding parts of races: when glycogen is low, muscles are tired, and yet you need to push — climb, sprint, or break away.

• Refine pedaling technique, cadence, and neuromuscular efficiency

Power isn’t just about strong legs — efficiency matters. A smooth, circular pedal stroke, correct cadence, and good neuromuscular coordination help you sustain power longer with less wasted energy. Cadence drills, technique focus, and core stability work all pay dividends. Think about how you pedal – so many cyclists totally ignore this, and yet this is how we power forward.

• Include strength training and off-the-bike conditioning

Endurance and power on the bike can be enhanced by off-bike strength training. Building muscular strength — especially in legs and core — improves torque, helps cycling economy, and supports fatigue resistance.

Also, good nutrition and proper fueling before/during rides is essential: if glycogen or glucose runs out mid-ride, your ability to produce high power degrades fast.

How to practically integrate this if you’re an amateur or recreational cyclist

Here’s a sample weekly structure:

• 1–2 low-intensity endurance rides (Zone 2), 1–3 hours each — builds aerobic base and fat-burning efficiency.
• 1 tempo or sweet-spot interval session (e.g. 2 × 20 min at ~90% FTP) — builds sustained threshold endurance.
• 1 VO₂max / interval session — e.g. 4–6 × 3–5 min at high intensity, with recovery.
• 1 long ride with fatigue simulation — e.g. 2.5–4 hours steady, finishing with a short hard effort or time-trial; or ride until a target kJ threshold and then do a 20-min all-out.
• 1–2 strength / core workouts off bike — e.g. squats, lunges, core stability, to build muscular resilience and power.
• Recovery / easy spins or rest days, plus good nutrition and hydration (both on and off the bike).

This kind of mixed plan gives you the volume, intensity, and variety to build not just peak power — but power that lasts.

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Why this approach matters — beyond arbitrary watt goals

Many riders aim to raise their FTP or max watts, but those metrics don’t always translate into real-world performance. In races — or long weekend rides — what matters often isn’t your 5-minute power, but how you ride after hours of effort; how you respond to attacks when you’re tired; and how your legs behave when glycogen is depleted.

Tracking and training around total work done (kJ) gives you a more holistic fitness benchmark. You force your physiology to adapt to fatigue — building aerobic capacity, muscular and neuromuscular durability, metabolic efficiency, and mental resilience.

It also helps you train smart: you’re not just chasing watt gains, but building the capacity of your engine, so you have the fuel and endurance to ride hard late in the ride.

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Some caveats / what “3,000 kJ = magic number” doesn’t tell you

• kJ ignores intensity. Doing 3,000 kJ at a very easy pace is very different than doing 3,000 kJ with lots of tempo and threshold efforts.
• Individual differences matter. Rider weight, fitness level, training history, recovery, nutrition — all change how kJ translates to performance. A lighter rider will take longer to rack up kJ at endurance pace; a heavier rider may hit it sooner.
• Time constraints. Many amateurs can’t ride 20–30 hours a week like pros. Instead of 80/20 volume-intensity splits, you may need to prioritise efficient, mixed workouts (sweet-spot, intervals, longish rides).
• Need for recovery and good fueling. Training stress must be balanced with adequate sleep, nutrition, and rest — especially when doing high workloads.

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Bottom line: build the ENGINE — don’t just chase watts

I have coached many athletes who, when they first come to me, are focused on hitting a Moby Dick number – they may well find the mythical ‘white watts’, but it will near-destroy them in the process. Often this way of thinking about performance inhibits development, because one area become stronger to the detriment of other equally important areas.

If you want to be a stronger, more resilient cyclist — whether for long weekend rides, gran fondos, or racing — shifting the mindset from “peak watts” to “sustainable power under fatigue” can pay off.

Use a power meter (or reliable head-unit) to track kJ. Periodically test your performance fresh and after fatigue. Structure a mix of endurance rides, threshold/tempo work, interval sessions, and fatigue-loaded long rides. Supplement with off-bike strength training, good nutrition, and recovery.

Over the months, the years, you’ll build a bigger tank — one that can carry you far and still summon power when it matters. That’s the kind of engine that wins races, survives long rides, and leaves you better equipped to find out just what you have in you.

Looking for coaching? See my CPCS Training Plans here!