Cardio sells more bad advice per minute than any other corner of the fitness industry. Let's clear the smoke.
Myth #1: “The fat-burning zone is the most effective for fat loss.”
Reality: the “fat-burning zone” (60–70 % max heart rate) burns a higher percentage of calories from fat. But it burns far fewer total calories than higher intensity. For fat loss, total calories burned matters — not the percentage from fat. A 30-minute HIIT session burns more fat than a 30-minute fat-burning-zone session, every single time.
Myth #2: “Fasted cardio burns more fat.”
Reality: fasted cardio burns slightly more fat during the workout but slightly less throughout the rest of the day. Total daily fat loss is roughly identical. The only edge of fasted cardio is preference — if you enjoy training fasted, do it. If you don't, don't.
Myth #3: “HIIT is enough — you don't need steady-state cardio.”
Reality: HIIT builds anaerobic capacity and conditions you for short, intense efforts. Steady-state Zone 2 cardio builds aerobic base, mitochondrial density, and the cardiovascular foundation that everything else stacks on top of. Both are needed. The best athletes do 80 % zone 2 and 20 % HIIT across the week.
Myth #4: “You should do cardio before lifting to warm up.”
Reality: doing more than 5–10 minutes of cardio before heavy lifting impairs strength performance for the rest of the session. A quick general warm-up on a rower or air bike is fine. A 30-minute steady-state ride before squats is not.
The right sequence: 5 minutes general cardio → mobility work → lift → finishing cardio if needed.
Myth #5: “Treadmills are the best cardio machine.”
Reality: treadmills are a cardio machine. They're great for runners. For most other purposes, a curved treadmill, rower, air bike, or SkiErg builds conditioning faster with less joint impact. The right cardio machine depends on your goal, not on tradition.
See our full breakdown: Curve vs Motorized Treadmill Guide.
Myth #6: “Zone 2 means walking.”
Reality: Zone 2 is the upper end of conversational pace — you can speak full sentences but not sing. For most fit adults, that's a moderate jog, a brisk cycling effort, or a Tempo-ish rowing pace. Not a stroll. Real Zone 2 work builds aerobic base; walking maintains general health but doesn't drive aerobic adaptations the same way.
Myth #7: “The calorie counter on cardio machines is accurate.”
Reality: treadmill and elliptical calorie counts are wildly optimistic — typically 20–40 % too high. Air bike and rower counts are much more accurate because they measure mechanical work directly. Use machine calorie counts for relative comparison (“I did 20 % more work today than yesterday”), not absolute caloric tracking.
Myth #8: “You need to do cardio every day to lose weight.”
Reality: you need to be in a caloric deficit to lose weight. That deficit can come from food alone, cardio alone, or both. 3 quality cardio sessions per week plus a managed diet beat 7 sessions of cardio with no diet structure, every time.
Myth #9: “More cardio is always better for the heart.”
Reality: for cardiovascular health, the dose-response curve flattens around 4–5 sessions per week of moderate cardio. Beyond that, additional volume is for performance, not for health. The first 30 minutes per day, 5 days per week, gives you most of the longevity benefit. Everything beyond that is for the sport.
What actually works for fat loss (the honest hierarchy)
- Caloric deficit through food. 200–500 cal under maintenance, sustainable.
- Strength training. Preserves muscle in deficit. The single biggest body-composition lever.
- Daily steps. 8,000–12,000 steps. The unsexy non-exercise activity that matters more than any single workout.
- 2–3 cardio sessions per week. Mix of Zone 2 and HIIT.
- Sleep. 7–9 hours. Bad sleep wrecks appetite hormones.
The honest summary
Cardio is a tool, not a religion. Use it for what works: building aerobic base (steady-state), building conditioning capacity (HIIT and air bike), and burning incremental calories during a fat-loss phase. Skip the gimmicks. Skip the fasted-cardio dogma. Use machines that measure your actual work, not your theoretical calorie burn.
The two cardio machines that tell the truth: the IRONSIDE Glam Premium Air Bike ($1,274) and the IRONSIDE Air Runner Curved Treadmill ($2,518). Build your cardio around these two and you'll never be lied to again.
Browse the full IRONSIDE cardio range.