Answer 5 questions to find your ideal cardio approach.
This quiz recommends a cardio approach — Zone 2, HIIT, or a mixed polarised model — based on your goals, available time, current fitness level, and preference for intensity. Each approach has distinct benefits and trade-offs; the right one depends on where you are and what you're trying to achieve.
Zone 2 keeps heart rate at 60–70% of maximum — the intensity at which you can comfortably hold a conversation. It trains the aerobic energy system, increases mitochondrial density, and improves the body's ability to oxidise fat as fuel. It's also the most sustainable form of cardio — low injury risk, low recovery cost, and sustainable as a long-term practice.
The downside: Zone 2 sessions need to be longer (at least 30–45 minutes) to be effective, and progress feels slow. The physiological adaptations are real and durable, but they take months to fully develop.
HIIT alternates between short bursts of maximum effort and recovery periods. It produces cardiovascular and metabolic adaptations in less time than steady-state cardio, and causes a meaningful "afterburn" effect (excess post-exercise oxygen consumption) in the hours following the session.
The trade-offs: HIIT is stressful on the body and requires adequate recovery. Done more than 2–3 times per week, it accumulates fatigue and increases injury risk. It's not appropriate as a daily practice for most people.
The polarised approach — approximately 80% low intensity (Zone 2) and 20% high intensity (Zone 4–5) — is the model used by elite endurance athletes and increasingly recommended for recreational exercisers. It avoids the "grey zone" of moderate intensity that's too hard to be truly aerobic and too easy to drive high-intensity adaptations.
In practice, this might look like 4 Zone 2 sessions and 1 HIIT session per week. The easy sessions feel almost too easy — that's intentional. Resisting the urge to make them harder is a discipline that pays off in long-term fitness development.
Zone 2 burns a higher proportion of fat during exercise. HIIT burns more total calories in less time and produces greater post-exercise calorie burn. For total fat loss over time, what matters most is total energy expenditure and adherence — neither approach is dramatically superior if you can stick to it consistently.
For people with limited time, HIIT is more efficient. For people who want a sustainable long-term practice with low recovery cost, Zone 2 wins. The polarised model is the best of both for people who can commit to consistent frequency.
How many HIIT sessions per week is too many?
More than 3 high-intensity sessions per week is too many for most people. HIIT requires 48–72 hours of recovery to avoid accumulating fatigue. Doing HIIT every day is a common mistake that leads to overtraining, elevated cortisol, and stalled progress.
Can beginners do HIIT?
Yes, but with modifications. True HIIT at maximum effort is demanding. Beginners should start with "interval training" — alternating moderate effort with rest — and build intensity gradually as fitness improves. Jumping into intense HIIT without a base level of fitness increases injury risk.
Does cardio type matter for heart health?
Both Zone 2 and HIIT improve cardiovascular health markers. Zone 2 is particularly effective for reducing resting heart rate, improving stroke volume, and reducing cardiovascular disease risk over time. HIIT improves VO2max more quickly. Both are beneficial; the best type is the one you do consistently.
Should I do cardio before or after weights?
For fat loss or general fitness, the order matters less than doing both consistently. If your priority is strength, do weights first when you're freshest. Zone 2 cardio after weights doesn't significantly impair muscle building. Intense HIIT before weights will reduce strength performance.