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High Intensity Interval Training - Micro HITT

Most people who go to the gym are likely familiar with the term HIIT. This exercise protocol involves brief periods of more intense exercise followed by a longer period of easy exercise repeated in intervals. Including warm-up and cool down these sessions normally last 30-45 minutes.

The benefits of HITT are increased fitness, body fat loss, muscle gain, improvements to metabolism, better sleep, improvements to mood and sex drive and many other benefits. In fact some studies have shown that 20 minutes of HITT leads to 3 times greater fat loss than 40 minutes of moderate exercise.  What about micro HITT sessions, something in the 4-15 minute range, what benefits does this impart?

The World Health Organization (WHO) currently recommends 150-300 minutes of moderate activity weekly, for some if not many that amount of time isn’t possible or realistic. We know that 75-100 minutes of vigorous activity weekly yields the same benefits, but what about micro or low-volume HITT, what does that do for you?

A new review published in the Journal of Physiology looked at a decade’s worth of research from various studies. From the data they considered low-volume HITT to be 15 minutes or less of intense exercise. The study shows that low-volume HITT yields comparable improvements to current guidelines requiring significantly less time.

This review builds on a previous study published in Diabetes Care which exhibited that as little as 4 minutes of HITT 3 times per week for 12 weeks significantly blood sugar levels, fatty liver, and cardiovascular health in adults with type 2 diabetes. The results were comparable to the effects of 45 minute sessions of moderate aerobic exercise. Many of the participants in the Diabetes Care study were surprised by how good they felt despite the shortness of their sessions.  Micro HITT may be even better when it’s only one part of an active lifestyle.

Belly Fat risks Beyond BMI

Whereas the risks associated with obesity are well reported where your fat is accumulated could be equally important.  According to a new statement published by the American Heart Association those with fat accumulation around the mid-section and organs have an increased risk of heart disease even when their BMI is within healthful limits. This statement offers the most recent information on the relationship between obesity and obesity treatment in heart disease, heart failure and arrhythmias.

Visceral fat that accumulates in the mid-section and around the organs is more metabolically active releasing hormones and other chemicals into the blood stream which can cause inflammation and increase the risks of type 2 diabetes, heart disease and some types of cancer.  

Those who sequester their fat below the waist exhibit no increased risk of heart disease even when their BMI is rated as obese according to various studies.  The real problems begin when it’s above the waist.  For this reason screening should include a visceral adipose tissue measurement (waist circumference to height ratio) as a risk assessment. BMI measurements don’t differentiate between muscle and fat weight making them less useful as a standalone assessment. An overly muscular person or athlete can sometimes measure as obese indicating the flaw with BMI.

To get your waist to height ratio place a soft tape measure between your bottom rib and hip bone, about an inch above your belly button. Stand relaxed without breathing in or tucking your abs in. Note the number in inches. Have someone help you measure your height without shoes on; also in inches. Divide your waist number by you height number.  For instance if your waist is 30 inches and your height is 70 inches divide 30 by 70 which equals .428. The number you’re looking for should be below .5 ideally. A higher number indicates elevated VAT to the point of health risk. There are counters available online that can break the results down further into categories such as lean, average etc.

The more information you have the better the position you are in to make small life style changes early that can lead to big changes long term.  The risks associated with obesity lead not only to a shortened life span, but also lower quality of life and significant financial burden. None any of us wants to contend with.

Stair Climbing Heart Test

A study published by the European Society of Cardiology found that the pace at which you can climb 4 flights of stairs or about sixty steps is a great indicator of heart health. The study included 165 symptomatic patients with suspected coronary artery disease exhibiting chest pain or shortness of breath. Test subjects were first given a standard treadmill stress test. After resting they were asked to climb 4 flights of stairs as fast as they could without running or stopping.

Exercise capacity was measured in metabolic equivalents or METs. Previous studies have shown that 10 METs is equivalent to very good heart health with a mortality rate of less than 1% in a year or 10% over 10 years.

Patients who were able to climb all 4 flights in under a minute had a METs measurement of 9-10. Test subjects who took longer than 1 ½ minutes had a METs reading under 8 METs which translates to a mortality ratio of 2-4% per year or 30% over 10 years, fully 3 times higher than the faster group.  The stair test coincided well with the stress test results.

This is a pretty easy self-test to gage your current heart health. The information you gain can inform if you are in good shape, need to make minor exercise changes or if further diagnostics may be necessary.  For those who take longer than 1 ½ minutes it would be recommended to consult your doctor. It is always a good idea to consult your physician before undertaking any new exercise related tests or exercise programs.

 References:

The Journal of Physiology 2021 – Low-volume high intensity interval training for cardiometabolic health

Sciencedaily.com – Keeping fit with HITT really does work

American Heart Association – Obesity and Cardiovascular disease: a scientific statement

AJMC.com – Waist to height ratio beats BMI for finding obesity

European Society of cardiology – Test your heart health by climbing stairs