Sweet Spot (MIET) Training for Cyclists Over 40: Build Fitness, Not Fatigue

When most riders talk about “sweet spot”, I smile — I’ve been coaching that effort for years under a different name: MIET — Moderately Intensive Endurance Training.
The term “sweet spot” caught on later, but the idea’s the same: ride just below threshold — hard enough to trigger change, easy enough to repeat tomorrow.

For masters cyclists, it’s the single most useful training zone you can master.

What MIET actually is

MIET sits around 90 % of FTP or RPE 7/10 — that “strong but sustainable” zone you could hold for two to four hours on a good day, depending on fuelling, mindset and fitness.
It’s below threshold, but high enough to build real aerobic strength.

At this intensity your body produces more lactate — but that’s not a villain.
Lactate is a valuable fuel, shuttled between fibres to keep muscles firing.
The real limiter isn’t lactate itself; it’s the hydrogen-ion (H⁺) accumulation that comes with hard work, which can interfere slightly with how actin and myosin (your muscle filaments) contract.
Researchers haven’t pinned down every detail, but we know this: lactate delays fatigue — it doesn’t cause it.
MIET keeps that system in balance: enough effort to adapt, not so much that acidity and fatigue win.

Why MIET matters more after 40

As we age, recovery and hormone response slow a little. Threshold and VO₂ sessions hit harder; full recovery can take days.
MIET delivers the aerobic stimulus we need with far less residual fatigue.

Benefits for masters riders

Builds aerobic durability — staying strong late in long rides.
Raises functional threshold indirectly by expanding aerobic power.
Keeps training repeatable — you can ride again tomorrow.
Improves psychological confidence — you finish sessions feeling capable, not crushed.

Finding your MIET zone

Use whatever tools you’ve got:

Power: ≈ 88 – 92 % of FTP
Heart rate: ≈ 85 – 90 % of threshold HR
RPE: 7 / 10 — steady pressure, breathing controlled, speech in short phrases.

If heart-rate drift climbs more than ~5 bpm or legs feel heavy early, you’ve gone too hard.

How much is enough

Consistency beats hero workouts.
Start with two MIET sessions per week, each 3 × 8 minutes with 3–4 minutes easy pedalling between.
That’s 24 minutes of real work — plenty to drive adaptation while keeping recovery intact.

Progress gradually:

Step 1 – 3 × 8 min
Step 2 – 3 × 10 min
Step 3 – 2 × 15 min
Step 4 – 2 × 20 min

Once you can handle that comfortably, you can fold MIET blocks into longer endurance rides.

Example week (8 hours total)

| Day | Focus |
| Mon | Rest or mobility |
| Tue | MIET 3 × 8 min @ 90 % FTP |
| Wed | 60–90 min Zone 2 |
| Thu | Strength 30 min (light) |
| Sat | Long ride 3 – 3.5 h (Z2 with 2 × 20 min MIET mid-ride) |
| Sun | Easy spin or family ride |

Recovery signals to watch

Sleep quality ↓ or resting HR ↑ = back off.
RPE climbs for same power.
Mood or motivation dip.
Respond early; swap a MIET session for endurance instead.

The bottom line

MIET is efficient, sustainable training for grown-up legs.
Work just below threshold, repeat it weekly, recover well, and you’ll build fitness that lasts.

**Want to train smarter?** Download my free guide: [The 6 Pillars of Cycling Performance] Evidence-based strategies used by world champions and weekend warriors alike.

Richard SternOctober 20, 2025