CTL ramp rate — the 3.5 rule explained with real numbers

Open any PMC on any platform and you’ll see a blue line climbing. That’s CTL — your 42-day exponentially weighted average of daily TSS. Everyone wants it high; nobody reads the speed limit. The rule of thumb every competent coach respects is simple: experienced amateur athletes shouldn’t raise CTL faster than 3.5 points per week on average. Returning athletes, 2.5. Anything above 5 for more than a week or two is injury territory.

This post is about what those numbers actually look like in a real training block, where the rule comes from, and why ramping faster almost always backfires even when you can handle the absolute load.

Where the number comes from

The 3.5-per-week figure isn’t pulled out of the air — it’s a distillation of two overlapping bodies of evidence. Clinical literature on soft-tissue adaptation (tendon, ligament, cartilage) shows structural remodeling lags cardiovascular fitness by 4–8 weeks. If CTL grows faster than the body can remodel, the mismatch shows up as tendonitis, bone stress, or frequent illness. Meanwhile, coaching literature (Friel, Coggan, Joe Friel’s 10% weekly rule for running) converges on a similar ceiling when translated to TSS terms.

3.5 CTL/week isn’t a line above which you’re guaranteed injury. It’s the line above which injury risk climbs faster than your fitness does. You can go higher — pros routinely do — but you’re paying an increasing risk premium per CTL point.

What 3.5 CTL/week actually means as weekly TSS

The tricky part: CTL responds exponentially, not linearly, to weekly TSS. You can’t just say “add 25 TSS per week” — the relationship depends on where you’re starting.

A useful approximation: in steady state, weekly TSS ≈ CTL × 7. So an athlete sitting at CTL 60 needs about 420 weekly TSS to maintain. To climb by 3.5 CTL in a week, add roughly 35–45 TSS to that baseline — call it 460 TSS the next week.

At CTL 80, maintenance is about 560 weekly TSS. To climb 3.5, aim for 600. The amount you add scales with your current level, which is why experienced athletes can absorb more absolute stress than beginners — their whole curve is higher.

A worked 10-week build

Amateur cyclist, starting CTL 50, target CTL 80 by the end of a 10-week block. Let’s see if 3.5/week gets us there, and what the weekly TSS targets look like.

Weeks 1–3 (re-entry, 2.5 CTL/wk)

• Week 1: 380 TSS → CTL 52
• Week 2: 420 TSS → CTL 55
• Week 3: 440 TSS → CTL 57

Weeks 4–6 (build, 3.5 CTL/wk)

• Week 4: 490 TSS → CTL 60
• Week 5: 520 TSS → CTL 64
• Week 6: 480 TSS → CTL 67

Week 7 — deload

• Week 7: 320 TSS → CTL 67 (holds — a good deload preserves, not destroys, CTL)

Weeks 8–10 (peak, 3 CTL/wk)

• Week 8: 520 TSS → CTL 71
• Week 9: 560 TSS → CTL 75
• Week 10: 540 TSS → CTL 78

Final CTL 78, not quite the 80 target. That’s realistic: average 2.8 CTL/week over 10 weeks, with a deload that holds steady. Athletes who insist on hitting exactly 80 end up pushing 4.5+ per week in the final phase, and the injury rate in that scenario is notably higher. Landing at 78 in one piece beats landing at 82 and losing the next three weeks to tendonitis.

Signs you’re ramping too fast

Hard rule is 3.5/week, but four softer signals often fire first:

• Monotony drifting up. To cram more TSS into the week, athletes compress the hard-easy rhythm. Monotony above 1.8 is an early warning even if CTL ramp looks reasonable.
• TSB staying below −20 for more than two weeks. Means you’re not absorbing what you’re putting in. The body remembers; you’ll pay later.
• Morning HR creeping up. Classic overreaching signal. Not a ZoneTwo metric directly — requires a device — but a simple one to self-check.
• Niggles that don’t resolve with a normal rest day.Tight calf, sore Achilles, “dead legs” that persist through Sunday. The body is asking to go slower.

What to do when you’re above the ramp line

You’re already at CTL 78 with four weeks to race, you wanted 85, and the current trajectory is 5+ per week. What now?

Cap the ramp. Two weeks at maintenance, then one modest build week, then taper. Arriving at CTL 80 healthy beats arriving at CTL 85 with an overreach flag and compromised race form. The final 5 CTL points rarely make a noticeable performance difference; injury definitely does.

If you’re ramping hard because of race-date pressure, the honest answer is to pick a later race. That’s not a fun answer. It’s also the correct one.

More on the curves: CTL, ATL, TSB, what is TSS, and training readiness.