We went for a long run in the hot sun, and my partner carried me up the stairs to our home and straight into the shower.

“How romantic,” I said ….. until he hit the cold tap.

“It’s good for you, Jac,” he grinned. “Shocks your system into life, hey?”

Recently, Mayo Clinic in Rochester, Minnesota, did a study on HIIT, high intensity interval training alongside other exercise regimes such as weight training, taking muscle biopsies of subjects under different exercise regimes to measure their impact on the cells. HIIT came up tops: it boosted the ability of the mitochondria within cells to generate energy by 69 per cent in older volunteers, and by 49 per cent in the younger group.

This is particularly important for 49-year-old me as mitochondrial activity declines with age.

The good news from the researchers at the Mayo clinic is that after three months of regular HIIT, “everything converged towards what we saw in young people”.  

For me, the best thing about HIIT is it requires no equipment and you can HIIT outdoors.  I love it and I do feel younger than I did a few years ago, despite a serious illness.

I generally do 30 minutes of HIIT, with my routines consisting of 45 seconds high intensity and 15 seconds low intensity activity. I often do star jumps and then run up stairs for the high intensity, and run down for the low intensity.

This is something I did, just for the purpose of illustrating what I mean. I love it, because it is outdoors, you can do HIIT anywhere, there are no rules (so long as your heart gets pumping) and most of all, it is fun!

Journal reference: Cell Metabolism, http://www.cell.com/cell-metabolism/fulltext/S1550-4131(17)30099-2