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Would you describe your last workout as light, moderate or vigorous? Not sure which one fits? You’re not alone. It’s not easy figuring out exactly how hard you’re exercising. And since more and more fitness professionals are emphasizing intensity over time, it’s worth reviewing whether your workout is vigorous enough to deliver the kind of results you want.
It’s common for certain activities to be grouped by intensity. Walking, hiking, doubles tennis and golf fall into the moderate category, while singles tennis and hockey are examples of vigorous exercise. Then there are activities like running, swimming, brisk walking and cycling that can be labeled moderate, vigorous or high intensity, based on the amount of energy the exerciser expends – hence some of the confusion about what constitutes a light, moderate, vigorous or high -intensity workout.
Exercise intensity is a reflection of effort, not activity, with several additional factors influencing the measurement, including fitness level, age, gender and genetics. An elite athlete will expend less energy running around a 400-meter track than a novice exerciser covering the same distance at the same speed. So while the elite athlete may describe the workout intensity as moderate, the novice will classify it as vigorous – something to keep in mind when you see activities like running, swimming and cycling labeled by intensity.
How do you know when a run, bike ride or swim transitions from moderate to vigorous? The easy answer is that you feel it. If it feels like you’re working hard, you probably are. Your heart rate increases, breathing is labored, your arms and legs feel heavy and fatigue starts to build. But even these clear signals leave some wiggle room for interpretation, since factors such as environmental conditions (too hot or too cold), a poor night’s sleep or stress can affect your perception. Plus, everyone’s sensitivity to effort is different, which can further broaden the chasm between perceived and actual effort.
Another measure of intensity is how long it can be maintained. Moderate-intensity exercise can be sustained for hours. Think of ultra-marathoners, long-distance swimmers, race walkers and cyclists who leave early in the morning and come back for lunch. Vigorous and high-intensity exercise can be maintained for a much shorter period of time, ranging from seconds to minutes, usually tapping out at less than an hour of intense exercise, and then only by the very fit.
A less subjective gauge of exercise intensity is heart rate, which increases with effort. Exercising at 55 to 70 per cent of your max heart rate, commonly calculated as 220 minus your age, is considered moderate intensity. Vigorous intensity is 71 to 90 per cent of max heart rate, with high-intensity exercise being above 90 per cent. So if you’re 45 years old and your heart is beating anywhere from 124 to 157 beats per minute, you’ve crossed over from moderate to vigorous intensity.
But even a measure as seemingly objective as a percentage of maximum heart rate has its weaknesses. The idea of adjusting maximum heart rate (220 beats per minute) with age is based on the fact that the heart slows down as we get older. So an older person working out at 124 bpm is working harder than someone younger with a matching bpm. But biological age isn’t always the best measure of fitness, so there are plenty of fit 60-pluses who would consider working out at 124 bpm to be more moderate than vigorous. Add the increasing number of people who are taking medication to moderate their blood pressure, and it’s easy to see why heart rate isn’t always a perfect measure of exercise intensity.
One of the simplest ways to measure intensity is one of the most accurate, and is also low tech and easy to do mid-workout. The talk test is based on the principle that as exercise intensity increases, breathing becomes more labored and speech harder to sustain. So if you can’t keep up your end of a conversation with your workout buddy, consider yourself in the throes of a vigorous workout. But if you can catch up on all the gossip with little pause between sentences, your intensity is somewhere between light and moderate.
If you’re exercising solo, try reciting a short nursery rhyme out loud. If you can do so normally, it’s a light-intensity workout. If you can say the whole rhyme but with a measure of breathlessness, you’re in the moderate range. If you can only grunt out a few words, it’s a vigorous workout. Can’t talk at all? You’re in that short, sweaty high-intensity zone that allows little if any conversation.
A close cousin of the talk test is the breath test, which notes that general movement becomes exercise once you can hear yourself breathe.
Armed with all this info, do you really need to monitor your exercise intensity? It depends. There are all sorts of additional health and performance benefits to be had from boosting the intensity of your workout, so it pays to know when you’re in the sweet spot between working hard enough and working too hard. But if your idea of a great workout is cruising along in that comfortable place between easy and hard, then keep at it.
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