Fitness Framework: Part 1

by Adam Toffan, M.Sc, NSCA-CSCS, CSEP-CEP Assistant Fitness Training and Assessment Coordinator, Recreation Services at the University of Manitoba

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In recent decades, the average time that people are physically active has decreased dramatically in Western countries. Physical inactivity has been named a big, if not even the biggest, health problem of the twenty-first century. We know it's important to be active and get moving. However, it can be very overwhelming and confusing with so many different numbers and recommendations. Today, I want to explain some of the science behind these recommendations and the differences in some of the common terms being used. 

Dose-response

"Dose-response" is a common term in exercise science. It means how much of a given stimulus you need to achieve for a given result. This is the cornerstone of recommendations. Examples include 10,000 walking steps a day or 150 minutes of moderate-vigorous activity (as recommended by the Canadian Activity Guide). One essential thing to consider with some recommendations is that we are all different. There is a considerable difference between people in how they respond to a given stimulus. Someone who has been largely sedentary will not need to do as much as a very active person to reach the same relative intensity. One person may be working at 85 percent of capacity while running 6k/hr., another may be closer to 55 percent. Therefore, many recommendations will speak about intensity in relative terms. Relative intensity is also why some recommendations seem more demanding than others concerning time commitment. Higher intensity exercise is harder to maintain, but you can also achieve as much work in a shorter period, so the duration is much lower. In contrast, a lower-intensity activity requires less energy and applies less stress to the body, so you can sustain the activity for a longer period of time.

Canadian Activity Guide recommendations

The Canadian Activity Guide suggests 150 minutes per week divided into 30 minutes of exercise, five days a week which can be broken up into 10-minute blocks if necessary. Two additional days with strength activities are also recommended. For the average person to take 10,000 walking steps per day, they would need to walk around 8 kilometres, which takes the average person 1 hour and 40 minutes depending on walking speed and stride length. 

So, which is it? The answer: it depends. 

Exercise at varying intensities has varying benefits (and varying degrees of benefits). The primary benefit of low-intensity exercises, such as walking 10,000 steps, is energy expenditure. On average, a person will burn an additional 2,000 – 3,500 calories per week. One pound of body fat equals 3,500 calories, so depending on your diet, weight and walking intensity, you could lose one pound per week by simply walking 10,000 steps per day. Some other benefits of walking 10,000 steps per day include improved blood cholesterol and blood pressure, increased bone health, relaxation and boosted energy levels. Research also shows that people who take at least 8,000 steps per day have a reduced risk of death over the next decade. 

Like the moderate-vigorous exercise recommended by the Canadian Activity Guide, higher intensity exercise has similar benefits, such as energy expenditure, weight loss, and improved blood pressure. However, the extra intensity also has additional benefits, such as effective control of blood sugar, reduced risk of illnesses such as Type 2 diabetes, Alzheimer’s disease and several forms of cancer. Perhaps the greatest benefit to higher intensity exercise than low-intensity walking is improved heart health which, in turn, reduces your risk of heart attack and stroke. Depending on your fitness level, activities that might qualify as moderate-intensity activity include brisk walking (>2.5mph), dancing and cycling (<10mph). Vigorous activities may include running, swimming, uphill hiking and cycling (>10mph). 

In conclusion, get moving!

Despite the different recommendations, the primary goal with each is to get people moving more and sitting less. Ideally, finding time for some more intense activity will give you additional benefits and reduce the risk of several conditions. However, if you can just make sure to move around throughout the day and get in many steps, you will still see some benefits and feel better overall.

Next week I will be looking closely at the terminology used in higher intensity exercise and what the differences are. Check back next week, but in the meantime, make sure to move daily. Fitness Framework: Part 2.

Sources

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Herold, F., Müller, P., Gronwald, T., & Müller, N. G. (2019). “Dose-Response Matters! - A Perspective on the Exercise Prescription in Exercise-Cognition Research”. Frontiers in psychology, 10, 2338. 

Saint-Maurice, P. F., et. al. (2020). “Association of Daily Step Count and Step Intensity With Mortality Among US Adults.” Journal of the American Medical Association, 323(12). Pp. 1151–1160. 

Tremblay, M.S., Shephard, R.J., Brawley, L.R. (2007). “Research that informs Canada’s Physical Activity Guides: An Introduction.” Applied Physiology, Nutrition and Metabolism, 32, S2E.