This week I had a client with 250 minutes of weekly cardio in his plan and a diary where they no longer fit. Instead of cutting the cardio, we traded part of the minutes for intensity. He ended up with the same calorie burn and an hour and a quarter less cardio per week.
Let me explain how this trade works, with the numbers, an example week and what to watch out for.
The calories you burn in a session depend on two things: intensity and time. If you raise one, you can lower the other.
Numbers for an 80 kg person: walking fast or cycling at 120 to 130 beats per minute burns about 6 to 7 calories per minute. In hard intervals it is around 14 calories per minute. These are estimates and they vary from person to person, but the ratio is stable and gives you a simple rule:
1 hard minute is worth about 2 moderate minutes.
Moderate is the cardio you are probably already doing: 120 to 130 beats, brisk walking, bike, stairs. You can hold a short conversation and you could keep going for an hour if you had to.
Hard is an effort of 8 to 9 on a scale of 10. The conversation stops. You do it in one-minute intervals because nobody can hold it continuously.
My client's example works for almost anyone on a 250-minute plan:
It saves more than an hour a week. There is also a small bonus: after an intense session your metabolism stays elevated for a few hours. The effect has been measured and sits at 5 to 10 per cent. Count on it as a small extra and nothing more.
The choice of machine is yours: bike, stairs, rower or running. If you are not used to running, start with the bike or the rower, which have almost no impact on the knees and the back.
High intensity asks for recovery. Two to three sessions a week is plenty. More than that and you start paying with your sleep, your mood and your performance in the gym.
Keep it away from leg day. Intervals the day before or on the same day as leg training take strength away from where you need it. Put the intervals on another day, or at least well away from that session.
If you are just starting out, this is not for you yet. Do a few weeks of moderate cardio first. Once you have a base, then you add intensity.
Your daily steps stay the same. The trade is in the cardio minutes; the steps in your plan carry on as they are.
If it were only a question of arithmetic, you would do the whole week in 80 minutes of intervals. In practice moderate cardio has advantages worth keeping: you recover from it quickly, it does not interfere with strength training, and you can do it even on the days when you are wrecked. People who build a plan of intervals only tend to abandon it after a few weeks.
So the base stays moderate, and intensity comes in only to make up the minutes the diary took away.
The best cardio is the one you can actually do every week. When there is no time for more minutes, there is almost always room for more intensity.
Queres um plano feito para ti, ajustado com os teus números?
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