Medical meetings canbe dull as ditch water. But occasionally you get something that is of interest to your everyday life – and that of your patients.
I have heard tell that intermittent exertion (high intensity interval exercise – or HIIT to use the jargon) instead of just plodding on with continuous exercise is better for your Cardio Respiratory fitness (CRF).
Weighing in on this debate at the 12thAnnual Obesity Summit sponsored by the Cleveland Clinic was Martin Gibala, PhD, Professor and Chair of Department of Kinesiology at McMasters University, Hamilton, ON.
He sited a slew of studies:
- One in overweight diabetics (BMI at least 30) on a walking regimen, where they got their heart rate up to 66% of maximum during the HIIT phase (to know your maximum heart rate, you subtract your age from 220). There was an increase of 1 MET (Metabolic Equivalent of Task – which is a reflection of the level of metabolic activity your body is capable of) in 4 months, in the interval walking group but not in the continuous walkers.
- A study of blood sugar, also showed interval walkers improved where the continuous walkers didn’t.
- A meta analysis of 65 studies of people with different degrees of obesity noted normal weight individuals “robustly improved” their CRF with interval training.
- Finally in a cycling study, both continuous and intermittent exercisers saw an improvement in insulin sensitivity (a crucial factor in obese and diabetic patients reflecting how efficiently your body metabolizes blood sugar) and 2 MET’s improvement in CRF, in both Butthe volumeof exercise in the interval group was five fold lowerthan the continuous group.
Dr. Gibala was promoting interval exercise in particular – telling people look for stairs to climb - they’re “available almost everywhere” he notes. Then do 20 second intervals at an RPE of 15 (RPE stands for Rating of Perceived Exertion – in other words how hard you seem to be exerting yourself - on the Borg RPE scale of 6 – 20, 15 is deemed as “hard” exertion).
This will improve your metabolic equivalent 1 MET he claims – and a 1 MET improvement is as good as a 2 inch reduction in waist circumference; a five point improvement in systolic blood pressure; or a reduction of 18 mg/dl in blood sugar from the point of view of your health.
Pretty good for just skipping up a few stairs.
You may worry if you suddenly start high intensity exercising that your heart might give out. But in yet another study looking at people in cardiac rehab’ half the subjects got the ordinary, continuous program. The other half had to exercise intermittently, getting their heart rate up to 90 per cent of maximal heart rate – so pretty intense). But the HIIT subjects didn’t crump any more than the steady continuous exercisers. The “risk for events was low in both groups” reassured Dr. Gibala.
And it is reported that people much prefer doing HIIT as it is more efficient and requires less time – and lack of time is the commonest objection cited for not exercising.
Excuse me. I think I’ll just stop this and run up stairs. . . . . . . .