Aerobic exercise (cardio) – health benefits and how to exercise at home

Aerobic zone – calculating and measuring heart rate

Cardio, or aerobic exercise, is any physical activity that we raise our heart rate into the aerobic zone, and keep it at that level for some time. This begs the question of what the aerobic zone is. Definitions vary, but generally speaking, the aerobic zone for anyone is roughly 60-80% of his/her maximum heart rate.

How do we find out our maximum heart rate? The [220 minus age] formula will give us a reasonably accurate estimate of your maximum heart rate – certainly accurate enough to calculate your own aerobic zone. For example, a twenty year old will have a theoretical maximum heart rate of 200 (220-20), of which a range of 60-80% is 120-160 heartbeats per minute.

Now, you may be saying to yourself how on earth is it possible to go the extra mile when running or cycling by measuring your heart rate and correcting your activity to stay in the aerobic range. Fortunately, it’s not that complicated. One option is to use conveniences like smartwatches, Fitbit, and the like, but even these technological indulgences aren’t necessary at all.

It’s sufficient to correct the cardio activity sensationally in such a way that you’re out of breath, but able to do it without a break for a relatively long period of time (say, more than 20 minutes). For someone this means running, for someone it means light jogging, whereas for an untrained overweight person a brisk walk will amply suffice.

If it is to be an effective cardio workout, it is stated that the heart rate needs to be kept in the aerobic zone for at least 15 minutes at a stretch. In practice, this means that the entire exercise will have to last at least 20 minutes (it takes a while to get from resting heart rate to the desired frequency).

Jogging, swimming, aerobics and other forms of cardio training

From the above, it is actually quite indifferent what physical activity is involved, as long as the prescribed heart rate range is maintained for a long enough period of time. Cardio can be playing football or tennis, jogging, swimming, climbing a mountain, shoveling in the garden, or any other moderate intensity activity. In terms of the quality of the cardio workout itself, all of these activities are equivalent (at a similar heart rate and amount of workout time).


Of course, in terms of impact on the musculoskeletal system, the activities listed are not equivalent. Cycling essentially engages only the legs, and even then only in a limited range of motion, while swimming engages more or less the whole body. Running can be painful for someone’s joints, while brisk walking uphill may not cause these problems.

So what cardio is best for you? You can only answer that for yourself, but in my opinion, enjoyment should come first. When you enjoy your chosen type of aerobic exercise, you’ll be far more likely to cultivate and maintain the habit long-term. Also, it should be something that you can easily access and that can be done year round. Skiing is great, but a few days or weeks of skiing a year will have virtually no long-term impact on your fitness and health.

In addition to personal preference, it’s worth taking your health into account. Running is great cardio, but joints get quite a workout when running on hard surfaces

(especially when combined with improper shoes or improper technique, for example). If your knees aren’t bothering you and you’re filing your running technique, there’s nothing to worry about; on the other hand, if you’re coming off your second knee surgery, it might be better to start differently.

Nordic walking, for example, is gentle on the joints, but if you live in the centre of a smoky big city and have asthma, walking fast through smog-covered streets probably won’t be the right thing for you either.

The last recommendation I’d like to mention is loosely related to the previous point about health. A lot of sports that are great as aerobic workouts engage the body asymmetrically (one side working differently and more than the other). Let tennis, hockey, sport fencing, and any other sport in which we hold a tool or ball in only one hand, or admittedly in both hands, but one side is loaded more (see hockey) be an example.

There is nothing at all wrong with practicing such sports, but one should be aware of the asymmetrical load, and try to compensate for it by supplementary exercise. When one only practices asymmetrical sports activity (and no other) for a long time, sooner or later it will have a negative effect on posture and back and spine health.

Aerobic and anaerobic exercise – what’s the difference?

Aerobic training never develops big and strong muscles, although some muscle stimulation understandably occurs. A middle distance runner will have far stronger legs than an untrained person, but again far weaker than a sprinter, jumper, or weightlifter. This follows logically from the very nature of aerobic versus anaerobic exercise.

Aerobic exercise is of moderate intensity and is done for a longer period of time, while anaerobic exercise is more intense and thus must be done for a shorter period of time. Since strength exercise requires a higher load, actually cardio and strength training are somewhat mutually exclusive. It can be done simultaneously to some extent, for example in circuit training where you alternate exercises almost without rest (so your heart rate stays high), but the two ways of training simply always limit each other.

So the bottom line is that anaerobic training is shorter, more intense, and stimulates muscle growth, strength, explosiveness, and speed, while aerobic training is longer, moderate intensity, and stimulates endurance, better oxygenation, and general metabolism.

Thus, it is ideal to incorporate both types of exercise, but to prioritize the one in which we want to improve more. Those who want to gain muscle mass can almost skip the cardio and do only strength training, while for the aspiring marathoner, on the other hand, cardio will be key, and strength training just an adjunct.

Rope jump
Photo: Stocklib

How to practice cardio at home?

If your preference of cardio is an outdoor activity like jogging, but you don’t feel like going out in bad weather, you can get a full cardio workout in the comfort of your home

. Just choose an activity, or combination of activities, that will get your heart rate up to the level you want, and stick with it for at least 20 minutes straight.

If you have a treadmill or exercise bike at home, there’s nothing to worry about, but I wouldn’t recommend anyone to get such bulky and expensive machines for the sake of cardio (unless you really don’t enjoy and motivate yourself much). A very ordinary 100 crowns jump rope will serve for aerobic exercise just as well, if not better, and can be thrown away in the closet after the workout.

For example, if you live in an apartment, where even slight bumps can spread to the neighbours, and you don’t want to annoy the surroundings by jumping, it is not a problem to choose another option than a jump rope. For example, you can choose a few moderate exercises, and alternate them with such pauses that the heart rate does not drop too much, but that the muscles can keep working long enough.

  • Example: squats, plank, and pushups alternate after such sets, so as not to exhaust ourselves too quickly (if I can do no more than 20 pushups in a set, I do them roughly 10 at a time), and we keep the maximum pause between sets to about 20 seconds. If we get to the point where the muscles are too exhausted, we rest for a while by “trotting” in place (this keeps the heart rate up, but gives the muscles some rest).

There are a theoretically unlimited number of examples of home cardio, it just depends on preference and degree of imagination. Intense dancing is a great aerobic workout, as is active video games like Wii or DDR.

I’d cite excessive stress (such as an argument) as an exception to the rule that cardio is defined only by heart rate and time. In a highly unpleasant stressful situation, the heart rate can be very high (even for a prolonged period of time), but from a health standpoint, this tends to have negative effects, and definitely can’t be counted as a workout. If it were, overworked stockbrokers would have better physiques than marathoners.

Usefulness of aerobic exercise for metabolism and cardiovascular system

What results can we look forward to when we practice cardio regularly and honestly? The circulatory and respiratory systems in particular will thank us, as the name suggests. A stronger heart and better blood circulation can prolong life, and will definitely improve its quality.

Proper blood circulation is absolutely essential for all life functions, and by improving it, one feels better, has a little more energy, even headaches can subside (if they are caused by insufficient blood circulation), and in cold weather one’s hands and feet won’t even need to suffer as much.

Lately, it is a popular but unfortunately somewhat misleading claim that cardio will not make one lose weight, because even with prolonged (one hour) exercise the body burns quite a few calories. If we judge the effect in this isolated way, and only take into account the calories burned immediately, it is true. A half hour burns only about 200Kcal (more or less depending on body weight and pace), which is roughly one donut.

However, the impact of regular cardio is far more important! For one thing, the exercise lifts our performance and therefore the calories burned, but more importantly, the aerobic workload doesn’t just burn energy during the performance, but also afterwards during recovery, and most importantly, regular exercise speeds up the metabolism, so that an experienced runner burns much more than an untrained person, even on a rest day.

That said, like any other form of training, cardio is a long-term investment that will only be fully felt after several months of conscientious effort. You may only burn 150Kcal the first time through, but you’ll burn double that during the hundredth time through, and you’ll also have a metabolism that burns the aforementioned extra doughnut every day even without jogging.

The same, even to a greater extent, applies to muscle mass or strength training. A mere 5kg of extra muscle mass will dramatically lift your daily caloric load just to eat the acquired muscle. This means that when you neglect neither aspect of physical fitness, your body becomes a machine that consumes pizza and greasy fast food as fuel.

Michael Phelps
Photo: JD Lasica from Pleasanton, CA, US, CC BY 2.0, via Wikimedia Commons

Case in point, let world-famous swimmer Michael Phelps, whose daily diet puts even the discerning foodie and voracious glutton in your pocket. It includes lots of sweet food, like chocolate chip pancakes and toast with jam, whole pizzas, bowls of pasta, and so on. Looking at his worked out body capable of breaking records, a layman wouldn’t guess it, but to a knowledgeable athlete, it’s clear that given his daily performance, a horrendous caloric intake is not permissible, but literally necessary.

So don’t let the fact that the immediate effect is not noticeable discourage you from cardio, because physical fitness is built on the order of months and years, not days. Aerobic training is key to desired physical form, physical and mental health, and general quality of life. Plus, thanks to regular exercise, you’ll be able to indulge in your favorite foods more often without remorse, so feel free to go for it!

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