20 Minutes. Which Activity Wins?

The assumption is - you do not have time. This is a common excuse, built on misinformation.

Most people over 40 are running on a schedule with no obvious gaps in it. This issue - we need to look for the gaps. We need to prove we have the time to spare to get our butts down the gym, to a class or out of the house for a walk, jog, cycle or swim.

So let, as an example, work with 20 minutes.

That is the constraint. The concern should never be - 20 minutes is not enough, or which activity burns fat at the highest percentage.

Instead the reframe should centre on - which activity burns the most total calories in 20 minutes, or better yet which activity can I do for 20 minutes?

The answer will make the fat burning zone crowd uncomfortable (should you fall into this category - check this QW on the very subject: [link to Your Body Has Three Fuel Sources]).

Here is what the research shows for an average 80kg adult over 20 minutes.

Walking burns around 90 calories. Moderate cycling around 140. A steady run covers roughly 200. Strength training sits at around 160. HIIT - real HIIT, not a casual circuit - burns between 200 and 260 calories.

Same 20 minutes. Completely different result.

There is a post-exercise effect worth knowing about. After high intensity work your body continues burning at an elevated rate for one to three hours while it restores itself - lowering heart rate, repairing muscle and clearing lactate (the oh so lovely burning sensation you feel during exercise).

It is real. It is measurable.

It is not the 48-hour after-burn the fitness industry will try to sell you. A walk does not produce this effect in the same way. That is the honest difference.

Now the caveat - and this one matters.

HIIT at genuine intensity is not suitable for everyone. If you are returning after injury, dealing with joint pain, or have not exercised consistently in months, launching into sprint intervals is not the starting point.

The correct starting point is whatever you can sustain without breaking down. A 20-minute walk done consistently beats a single HIIT session that leaves you wrecked for days, and blaming the exercise, and not your approach.

Intensity follows capacity - not the other way around. A 20-minute walk becomes a brisk walk. A brisk walk becomes an interval walk. An interval walk becomes a walk / run intervals.

The engine and performance builds over time. There are (frustratingly) no short cuts, if they existed, I would have every client and member use them.

After each session this week, note two things: what activity you did and your perceived effort out of 10. Do this for the next two weeks. If the effort score for the same activity is dropping - your fitness is improving. That is the only number worth tracking right now.

If you want help working out where your 20 minutes should start, tell me about your situation. There are no wrong answers.

Build habits, not hurdles.