We all get old because our cells get old. The mitochondria in our cells that produce energy become more sluggish and lower in numbers. How can we slow down the aging process at a cellular level? I normally don’t quote studies from the journal Cellular Metabolism but this one was supportive of high-intensity aerobic interval training (HIIT) helping reverse the years on our mitochondria.

Researchers at the Mayo Clinic randomly allocated healthy but sedentary men and women who were 30 or younger or older than 64 to three different exercise groups involving 12 weeks of training.


Group 1: Resistance training (RT) involving vigorous weight training five times a week


Group 2: High-intensity interval training (HIIT), involving pedaling stationary bicycles hard for four minutes, resting for three and then repeating that sequence three more times three times a week.


4 min. X 3 = 12min. of high intensity exercise

3 min. X 3 = 9 min. of rest in between


Total HIIT time of 21 minutes

Group 3: Combined aerobic training (AT) and RT involving stationary cycling at a moderate pace for 30 minutes three times a week and RT twice a week.


Group 4: No exercise control group


Not surprising Result #1: After 12 weeks, everyone in Groups 1-3 experienced improvements in fitness and their ability to regulate blood sugar.

Not surprising Result #2: Those in the RT group had the greatest gains in muscle mass and strength.

Not surprising Result #3: Those in the HIIT group had the greatest gains in their endurance.

Surprising Result #3: When they analyzed biopsied muscle cells to look for changes at a cellular level, those in the HIIT group had increases in the number and health of their mitochondria especially in the older group.


Fascinating Result #4: At a cellular gene level, almost 400 genes were working differently after 12 weeks of HIIT, compared with 33 for those who did RT and 19 for those who did AT.


In conclusion: It appears that when those over 65 participate in high intensity exercises of short duration have greater positive changes in their cells than the younger population. Not only are you never too old to exercise, it’s the best time to do it …as long as you are medically safe to do so!


Examples of HIIT include hockey, squash, interval cycling, walk/run, and taking the stairs instead of the elevator for a few floors.


Personal comment: I am a fan of short duration high intensity movements because I get bored with monotonous continuous aerobic exercises. When I do something fast e.g. sprint for 10 seconds to the mailbox or quickly run up the stairs in my house, I am telling my brain, my genes and my body at a cellular level, yeah, I’ve still got it!


Reference: Robinson MM et al Enhanced Protein Translation Underlies Improved Metabolic and Physical Adaptations to Different Exercise Training Modes in Young and Old Humans. Cell Metab. 2017 Mar 7;25(3):581-592.

Mitochondria in cells

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