The mistake everyone makes
Open most fitness apps and the cardio section is one button labelled “cardio”. You hit start, your watch tracks heart rate, the app counts the calories. Job done.
Except it’s not. Zone-2 base work, tempo intervals, anaerobic-threshold pushes, HIIT and recovery walks ask completely different things of your physiology. Treating them as interchangeable is why most people train hard for years without getting measurably fitter. They’re collecting time in the wrong zones.
This isn’t an opinion. The five modes drive different adaptations, and you need a thoughtful mix of them.
Mode 1: Zone-2 (aerobic base)
What: Long, conversational efforts. Heart rate roughly 60–70% of your max. You could hold a conversation; you probably couldn’t sing.
What it does: Increases mitochondrial density (the engine count in each muscle cell). Improves the body’s ability to burn fat as fuel. Lowers resting heart rate. Builds the foundation everything else depends on.
How often: 3–5 times a week, 30–60 minutes each. The bulk of your weekly conditioning volume should sit here.
Mistake people make: Training above this band because it “feels too easy” and getting the wrong adaptations.
Mode 2: Tempo (sustained Zone 3)
What: Sustained efforts at roughly 70–80% of max heart rate. You can speak in short sentences. Long sentences become uncomfortable.
What it does: Pushes your lactate threshold higher — the point at which lactic acid starts accumulating. Higher threshold means you can sustain a faster pace before fatigue catches up.
How often: Once a week, 20–45 minutes. This is the work that hurts but isn’t fully painful. It’s the most-skipped mode because it’s neither comfortable nor dramatic.
Mistake people make: Treating every cardio session as a tempo session. You can’t recover from that, and the adaptations stop coming.
Mode 3: Anaerobic threshold (Zone 4)
What: Short, hard pushes at 80–90% of max. Speaking in single words. The pace you could hold for 10–15 minutes if you absolutely had to.
What it does: Improves your VO2 max — the maximum oxygen your body can use during exertion. This is the metric most strongly correlated with healthy ageing.
How often: Once a week, briefly. Typically 4–8 minute intervals with full recovery between. Rarely more than 15 minutes total work.
Mistake people make: Doing this too often. Anaerobic-threshold work is metabolically expensive. Twice a week is too much for most people; three times destroys recovery and stops the adaptation.
Mode 4: HIIT (high-intensity intervals)
What: Maximal-or-near-maximal efforts (Zone 5 — 90%+ of max) interspersed with recovery. The classic example is 30 seconds all-out, 90 seconds easy, repeated 6–10 times.
What it does: Stresses the alactic and anaerobic energy systems. Improves peak power output. Useful for sport-specific conditioning. Often misunderstood as a fat-loss panacea — it’s not.
How often: Once a week, briefly. 15–20 minutes total session including warm-up.
Mistake people make: Doing HIIT for fat loss instead of using Zone-2 + nutrition. HIIT burns calories during the session but you can’t do enough of it weekly to drive significant fat loss. Use it for fitness, not weight loss.
Mode 5: Recovery (active recovery)
What: Slow walks, gentle mobility flows, breathwork. Heart rate well below Zone 1 — usually 50–60% of max at most.
What it does: Promotes blood flow without adding to training stress. Helps you absorb the work you’ve done. Lowers stress hormones. The mode that lets all the other modes actually stick.
How often: Every day, especially after hard sessions. 20–30 minutes minimum.
Mistake people make: Treating recovery as “doing nothing”. Recovery is an active practice. The clients who get the most out of training are the ones who recover deliberately.
How we mix them in client programming
For a typical client training 4 sessions a week (2 strength + 2 conditioning) plus daily walking, a representative week looks like:
- Mon: Strength session + 30 min Zone-2 walk
- Tue: Recovery walk (45 min Zone 1)
- Wed: Conditioning — Zone-2 + tempo block (45 min total)
- Thu: Strength session + 30 min Zone-2 walk
- Fri: Recovery + mobility (30 min)
- Sat: Conditioning — Zone-2 base + one short Zone-4 effort (45 min total)
- Sun: Long Zone-2 walk (60+ min) or rest
That’s roughly 4 hours of conditioning a week, only 15–20 minutes of which is “hard”. Most of the work is comfortable. The adaptations come from the volume, not the intensity.
This is the opposite of what most people do — which is to train at a moderate-to-hard intensity for an hour every time, getting medium adaptations and chronic fatigue.
How the app shows this
Inside MyPT, each conditioning session is tagged with its mode. The app shows you which mode you’re supposed to be in for that session, and during the session it shows your current zone live (if you have a wearable) so you can stay in the right band.
We tag the mode because the mode matters. The right mix, sustained for months, makes you genuinely fitter. The wrong mix — even with a lot of effort — wastes the work.