I do my high-intensity interval training twice a week, before breakfast on Tuesdays and Thursdays.

This high-intensity interval training approach is one in which speed and effort are changed to take your heart rate up and down on an interval basis, the duration of each interval being governed by heart rate and timing.  The duration of the cardio session is shorter than for MISS at 20 minutes.

This can be done either on cross-trainer or treadmill, only using the treadmill if you (and your knees) are happy with running – which mine are.

Each hard interval is two minutes at a particular speed on the cross-trainer or treadmill.

Each easy interval is however long it takes until your heart rate comes to your lower figure.

The lower heart rate figure is 65% of your theoretical maximum heart rate (65% of 220 – age).  At example age of 55, maximum heart tare of 165, this becomes 107.

You will need to experiment to find the correct hard figure to start with.  I’ve found for many in the past that 12kph on a treadmill is a good figure to start, or using level 16 if it’s a cross-trainer, but please experiment.

Each hard interval takes two  minutes. This takes your heart above your anaerobic, or lactate, threshold.

Once you hit that time, switch to an easy interval by setting the level down to 1 on a cross-trainer or maintaining minimum speed – perhaps 3kph – on a treadmill (but always moving) until you reach the lower heart rate figure. Then straight back to doing a hard interval again, and continue following this up-down-up-down cycle until the 20 minutes are done.

Each hard interval should be 0.1 kph harder than the previous one.  So the second hard interval on the first day is 12.1kph, the next one 12.2 kph – if you started at 12kph.

And the starting speed for a hard interval increases by 0.1kph each day.  So, start at 12kph day 1, start at 12.1 kph day 2 and so on (then add the 0.1 for each interval as mentioned above).

The very first hard interval of each session should be built up to slowly – don’t immediately jump in at 12kph on day 1, 12.1kph on day 2.  Take a minute of the two to build up to this – but be on the target figure for the first hard interval after that first minute.

I find this combination of working to meet these metabolic thresholds to be most effective approach to both fat reduction and improving my own cardiovascular fitness level. It also adds interest and mental stimulation to the cardio.

Check your progress in CV fitness by noting how many cycles you can perform in the 20 minutes. The recovery time, the time taken for the heart to reach the lower heart rate number during an easy interval gets shorter as cardiovascular fitness improves.

(For me as an example, when I started this approach in 2010, I could do 4 cycles in the 20-minute period. But since then, my fitness has improved and I can now perform 7 intervals in the 20 minutes, and I hope my CV fitness will improve further over the coming months such that I will be able to perform 8 intervals in that 20 minutes.)