Advice about “the best” exercise is confusing. That is because the goal establishes the type of exercise recommended.
A survey from 2013 showed that only 50 per cent of adults considered themselves “active.” In 2017, the obesity rate (those with BMI’s above 30) in Saskatchewan is a shocking 45.9 per cent, an increase of 16.1 per cent over 2004. We continue to have the highest obesity rate in Canada. How can we improve this?
Many articles have informed us that exercise can reduce cancer rates. For example, a 30 to 40 per cent reduction in colon cancer and 20 to 80 per cent reduction in breast cancer requires 30 to 60 minutes of moderate to vigorous exercise per day. A 2016 article in the Journal of American Medical Association (JAMA) reported that exercise can reduce cancer in uterine, ovarian, liver, stomach, kidney, multiple myeloma, bladder and lung. Current recommendations are for 150 minutes per week of moderate exercise, 75 minutes per week of vigorous exercise, or 30 minutes of strenuous exercise per day, five days per week.
Vigorous activity is defined as: Your breathing becomes deep and rapid. You sweat after a few minutes and you can’t say more than a few words without causing you to breathe. Moderate activity: Your breathing quickens, but you are not out of breath. You have a light sweat after 10 minutes and you can hold a conversation but you can’t sing.
How many of us are actually doing vigorous exercise?
Several years ago, many articles appeared in the literature about High Intensity Interval Training or HIIT. HIIT involves short bursts of maximal effort followed by rest, resulting in 10 to 15 minutes of vigorous exercise. The beauty of this is that it doesn’t matter what your fitness level is, you can benefit from this approach. If you have a heart condition, you need to be assessed to see if you can exert yourself and your exercise initially would need to be supervised. This has been studied in people with coronary artery disease, congestive heart failure, multiple sclerosis (MS), obesity and heart transplants. There were more cardiac deaths in the control group than those who did this vigorous exercise!
For diabetic and obese patients it is particularly exciting because of the effect on muscle. These people have insulin resistance. Insulin is produced in the pancreas and is responsible for carrying the sugar into cells to be used for energy and it stores excess glucose in the liver and muscles as glycerine. In pro-inflammatory states, metabolic syndrome and diabetes, these organs become resistant and require higher levels of insulin to take glucose into the cells, straining the pancreas to keep up.
Exercise reduces insulin resistance and lowers blood sugar. It also helps build up muscles and makes them metabolically active, improves the blood supply, increases exercise tolerance and time to exhaustion.
A recent study done by Dr. Sreekunaran Nair, an endocrinologist from the Mayo Clinic, was extremely interesting. He studied 72 sedentary men and women for 12 weeks; half were under 30 and the other half over 64. There were four groups: (1) vigorous weight training two times a week; (2) brief interval training vigorously riding a stationary bike for four minutes followed by three minutes of rest, repeated three times per week and two days of 45 minute treadmill walking, and (3) a stationary bike at a moderate pace for 30 minutes five times per week and four days of light weightlifting. The last group (4) remained sedentary. All the activity groups had enhanced insulin sensitivity and lean mass. Resistance training and combined training had more improved strength; HIIT had a better effect on endurance.
This is where it gets interesting. The mitochondria are the engine of the cells. As we age, the mitochondria do not function as well; they reduce in number and we lose muscle mass. They used muscle biopsies to examine changes in muscle tissue and influence on DNA. In the HIIT, there were 400 genes that worked differently; only 33 in weight training and 19 for moderate exercisers.
What does this mean? HIIT had a positive influence on the muscle protein and mitochondrial function, reversing some of the age-related changes within the cell. The muscles functioned better and increased in size.
It is amazing how complex our bodily functions are… so complex that we are just beginning to identify cellular physiology. What is clear is that what we do can influence our long-term health in many ways. Perhaps this reprogramming our DNA function is how we can influence the development of cancer. This is a leap of faith on my part but it makes sense.
The bottom line is that we need to start looking at our statistics for activity and obesity and work to change the significant negative effects this can have on our health. I challenge you to examine your exercise choices and start adding short bouts of challenging intervals to improve your strength, endurance and insulin resistance. You can take charge of the only thing you have control over — your actions!
By Dr. Vicki Holmes