CTL Fitness Projection to September Race

Based on training data · Jan – May 2026 · Updated 14 May

What is CTL?

CTL (Chronic Training Load) is your fitness number — a rolling 42-day average of the daily training stress you've put on your body. Think of it like a bank balance for fitness: consistent deposits build it up, missed days slowly draw it down.

It's calculated from TSS (Training Stress Score) — a single number per workout that combines duration and intensity. A 30-min easy jog might be 30 TSS. A hard 12km tempo effort could be 90 TSS.

Higher CTL = more fitness. But it takes weeks to build — you can't cram it. And it decays in about 6 weeks if you stop training entirely.

Your current
~28
Up from 25 in late April. Build phase working — but still short of 10k race tier.
10k race ready
35–45
Solid for racing 10k well, not just finishing.
Half marathon
50–65
Comfortably handling ~50–60km/week.
Marathon ready
65–85+
Consistent 70–100km/week for months.

Projected CTL — Now to September 2026

Actual CTL (to date)
Optimal build (no knee issues)
Conservative / knee-managed
Current trajectory (no change)
September race

⚠ The Knee Factor

3 weeks into the amber plan, with the Stryd data clearly capturing chronic left-side compensation and one fatigue-driven dip already (May 2 long run, ILR Bal 42.6%). The build is working — but the plan is the more conservative of the build scenarios. To stay on track:

  • Treat sharp pain as a full stop, not a "modify" signal
  • Monitor ILR balance trends after long runs and quality sessions
  • Strength A on Mondays loads exactly the muscles that need it — don't skip
  • Race weeks (W12, W19/W20) stay light — fitness is banked, not built, in the taper

If the knee flares during a build phase, CTL can drop fast — and unlike fitness, inflammation doesn't respond to "just push through it."

The Three Scenarios

🟢 Optimal Build — CTL ~60 by September

Requires averaging ~55–65km/week from now onward, with structured long runs (90+ min by peak weeks) and one quality session per week. Achievable if the knee fully clears and you're consistent. You'd arrive at the race genuinely fit — not just fit enough to finish.

Peak CTL: ~60–65 · Weekly km: 55–70 · Long run: up to 28–30km

🟡 Conservative / Knee-Managed — CTL ~42 by September

This is the amber plan you're following, with long runs gradually extending from the current 45 min toward 75–90 min in the peak weeks. Volume stays in the 35–48km range. You'll finish comfortably and the knee survives the build. Note: current implementation is even more conservative than this target and trending closer to CTL 37 at peak; lengthening Saturday long runs as the knee settles closes the gap.

Peak CTL: ~40–45 · Weekly km: 35–48 · Long run: up to 20–22km

🔴 No Change — CTL crashes to <5 by September

If training stops or becomes patchy (mostly short runs, big gaps from knee flares), fitness erodes steadily. By September you'd be below your January starting point. Not a race plan — just hoping for the best.

Peak CTL: ~28 → decay to ~5 · Weekly km: <15 · High injury risk from undercooked legs