Slow enough to chat, fast enough to count

Most beginners run, cycle or swim too hard on their easy days and too easy on their hard ones. Everything ends up at the same medium-grumpy effort. "Zone 2" is the name coaches give to the genuinely easy end: an effort you could hold for a long time while still talking.

You don't need a watch to find it. You need one test and a rough idea of your heart rate range, and the tool below gives you both.

The talk test beats the number

Heart rate is a proxy for how hard your body is working. Breathing is closer to the real thing. As you speed up, there is a point where your breathing gets noticeably heavier and full sentences become awkward. Research has found that this point lines up reasonably well with the lab-measured "first threshold" where effort stops being purely easy. That is why the talk test is popular: it is free and it works on a hot day, uphill, or when you slept badly and your heart rate runs high.

• Easy (zone 2): you can speak in full sentences, breathing is deeper but controlled.
• Moderate: you can speak, but you would rather say short phrases.
• Hard: a few words at a time. Fine in small doses, not for most of your week.

Find your range

The old rule "220 minus your age" is a rough guess. A large analysis of studies (Tanaka and colleagues, 2001) found 208 − 0.7 × age fits better across ages. Even so, real maximums vary by roughly 7–11 beats per minute either side of the estimate, so treat the zones below as a starting point and let the talk test overrule them.

How to use zone 2 in your week

For a first-year plan, a simple shape works well: two or three easy sessions of 20 to 45 minutes, plus one slightly harder session if you feel like it. Build the length before the pace. If a run at easy effort means you have to walk, that is normal: alternate running and walking and let the running pieces grow over the weeks.

Easy days feel almost too easy at first. That is the point. They add up to a lot of training you recover from quickly, which leaves you fresher for the sessions that are meant to be hard.

When the number and the feeling disagree

Heart rate drifts upward with heat, dehydration, caffeine, poor sleep, illness and long sessions. On those days, go by the talk test and let the number run a bit high. Wrist sensors can also lag or misread during fast changes in effort, so a chest strap is the more reliable option if you care about the figures.

If you get chest pain, unusual breathlessness, dizziness or palpitations when you exercise, or you have a heart condition or take medication that affects heart rate, speak to a doctor before using zones like these. They are a general guide, not medical advice.

What to take away

• Easy means you can hold a conversation. Use that as the main test.
• Use the age-based range as a starting guess, not a rule.
• Most of your cardio can be easy; keep hard efforts short and occasional.
• Build time at easy effort first, speed later.