CoachingAnswer

HOW DO I BUILD ANAEROBIC CAPACITY?

By Anthony WalshRoadman CyclingUpdated 26 May 2026

ANSWER

Build anaerobic capacity with short, maximal or near-maximal efforts of 20–60 seconds — over-under intervals, standing starts, and sprint repeats. This energy system powers the accelerations, attacks and surges that decide racing outcomes. Most structured training plans focus exclusively on FTP and VO2max and leave anaerobic capacity undertrained. Two targeted sessions per week over a 4–6 week block moves the dial significantly.

KEY TAKEAWAYS

Anaerobic capacity powers efforts of 10–120 seconds — attacks, surges, short climbs and sprint finishes.
20–60 second maximal efforts with 3–5 minutes recovery are the core training stimulus.
Over-under intervals (alternating below and above FTP) build the ability to clear lactate and recover while still riding hard.
Anaerobic capacity is the most trainable short-term energy system — gains appear within 3–4 weeks.

WHO THIS IS FOR

IS THIS YOU?

The club racer who gets dropped on surges

You can hold tempo with the group but get shelled whenever the pace accelerates sharply.

The rider who struggles to respond to attacks

You have solid FTP but can't match the short explosive efforts that decide race situations.

THE ROADMAN VIEW

Here's what most training plans miss: FTP tells you what you can sustain, VO2max tells you what your ceiling is — but anaerobic capacity tells you what you can do when neither of those things matters and someone just attacks out of the corner. That's the real-world energy system for most cycling situations, and it's systematically neglected.

Alex Welburn made a sharp point about this on the podcast. The metrics most amateurs track — FTP, TSS, CTL — don't capture W' (W prime), the anaerobic work capacity bucket that determines how many hard efforts you can make before you genuinely can't respond. A rider with a big W' can handle repeated attacks and still have legs for the final sprint. A rider with depleted W' is cooked the moment the second acceleration comes.

The fix is specific: short, hard efforts with enough recovery to go genuinely hard again. These sessions are uncomfortable enough that riders avoid them. But a 4-week block of twice-weekly anaerobic work typically makes the surge and attack response night-and-day different. Cory Williams trains this way explicitly — his ability to throw 1,600 watts repeatedly in a criterium comes from systematic anaerobic capacity work, not just natural talent.

EXPERT EVIDENCE

WHAT THE EXPERTS SAY

Alex WelburnCycling coach and physiologist, Critical Power researcher
W prime — the anaerobic work capacity that sits above critical power — is a measurable, trainable system that determines how many hard efforts you can make in a ride. Most amateur training builds aerobic fitness while leaving W prime chronically underdeveloped.
Hear it: Why Your CTL Is Wrong | Roadman Cycling Podcast
Cory WilliamsProfessional criterium specialist, Legion Cycling Team
Criterium racing is decided by the ability to produce repeated short, high-power efforts separated by incomplete recovery. That's an anaerobic capacity problem as much as a sprint power problem. You train it specifically or you hope for a clean sprint — and most races don't give you one.
Hear it: Criterium Secrets: Get Ahead of 99% of Your Competition | Cory Williams

PRACTICAL APPLICATION

DO THIS WEEK

Add a short-effort session twice a week
After a 20-minute warm-up: 8–10 efforts of 30 seconds at maximal or near-maximal power, with 3 minutes easy spinning between each. Total hard work is only 4–5 minutes but each effort must be genuinely maximal to stress the anaerobic system.
Introduce over-under intervals
12–15 minutes alternating 1 minute at 120% FTP with 1 minute at 85% FTP, repeated. This drills the ability to clear lactate and recover while still pedalling hard — the exact demand of attacking and recovering in group racing.
Extend W prime gradually
Progress over 4 weeks: week 1–2: 30-second efforts at maximum; week 3–4: add 45-second efforts at 115% FTP. Track peak power on each effort. When it stops declining between weeks, the anaerobic system is adapting.

COMMON MISTAKES

WHAT CYCLISTS GET WRONG

MISTAKEOnly ever training FTP and VO2max and wondering why attacks drop you.
FIXAdd one anaerobic session per week in the 4–6 weeks before a race block. Short, maximal, well-recovered. The transfer to race situations is almost immediate.
MISTAKEDoing over-unders without adequate base aerobic fitness.
FIXAnaerobic sessions work best on top of a solid aerobic foundation. Without it, you're not building on anything — the high-intensity work just creates fatigue without a recovery system to absorb it.
MISTAKETaking too little recovery between maximal efforts.
FIXMaximal 30-second efforts need 3 minutes minimum recovery. Any less and you're not accessing the anaerobic system — you're doing fatigued aerobic work with high perceived effort.

FAQ

FREQUENTLY ASKED QUESTIONS

What is W prime in cycling?

W prime (W') is the total amount of work you can do above your critical power before you have to reduce intensity. Think of it as a rechargeable battery — you deplete it with hard efforts above threshold and recharge it during recovery. Training anaerobic capacity expands the size of that battery.

How long does it take to build anaerobic capacity?

Anaerobic adaptations are faster than aerobic ones. Most riders see meaningful improvements in 3–4 weeks of specific work. Peak anaerobic power — short sprints — can improve 5–15% in a dedicated 4-week block.

Is anaerobic training bad for endurance cycling?

No — it's complementary. A well-built aerobic base supports recovery between anaerobic efforts; anaerobic capacity creates the short-duration power that makes group rides and races survivable. The key is timing: anaerobic-specific work in build and race phases, on top of an aerobic base.

What's the difference between VO2 max and anaerobic capacity?

VO2 max efforts (4–8 minutes) stress the aerobic system near its ceiling. Anaerobic capacity (10–120 seconds) operates above that ceiling using stored phosphocreatine and glycolysis without oxygen. Both sit above FTP, but they're different systems requiring different training.

How often should I train anaerobic capacity?

Two sessions per week is effective for a focused 4–6 week block. Year-round, one session per week maintains the adaptation. These sessions are genuinely taxing — rest the day before and after each one.

RELATED EPISODES

HEAR THE CONVERSATIONS

Why Your CTL Is Wrong | Roadman Cycling Podcast

Criterium Secrets: Get Ahead of 99% of Your Competition | Cory Williams

Race Winning Interval Training | Roadman Cycling