'Cardio', short for cardiovascular exercise, refers to any form of rhythmic physical activity that increases heart rate and breathing so that the heart and lungs can supply oxygen to working muscles. Essentially, it's the type of exercise that makes us huff and puff while doing it and that many people dread.
Although people usually do cardio to lose weight, this type of exercise is associated with a number of health benefits such as reducing the risk of heart disease, stroke and falls. To top it all off, research shows that cardio also improves cognitive function and mental health.
The World Health Organization recommends a minimum of 150 minutes of moderate-intensity 'cardio', or 75 minutes of vigorous-intensity cardio, per week.
There are many ways to do cardio, from playing a team sport to biking to work or running every morning. In the gym, the most popular cardio machines are the treadmill, stationary bike and rowing machine. Those who can and want to invest in a device can also purchase them to use at home. But which one is the most suitable?
If we look at the effectiveness of the exercise, the treadmill takes the cake. Running uses most of the major muscle groups and therefore produces a greater increase in heart rate and energy expenditure compared to other activities, such as cycling.
Additionally, since running on a treadmill forces us to support the weight of our own body, it also helps strengthen and maintain bones, keeping them strong. This is even more important as we age, as it increases the risk of developing diseases such as osteopenia and osteoporosis, which reduce bone density.
However, the treadmill is not suitable for everyone. Weight-bearing while running can aggravate pain and cause swelling in people with common joint conditions, such as osteoarthritis.
Additionally, the treadmill is likely to require more maintenance (since most treadmills are motorized) and can take up a lot of space.
The stationary bike is another practical means to achieve our cardiovascular goals. Correct positioning of the bicycle is essential to feel comfortable and reduce the risk of injury. A general rule of thumb is that the knee should be slightly bent, as in the image below, when the leg is at the bottom of the pedal stroke.
Although cycling has important benefits for cardiovascular and metabolic health, being non-weight bearing does not benefit bones to the same extent as walking or running. On the other hand, it offers an excellent cardiovascular exercise without straining the joints.
If what we are looking for is to perform the best cardiovascular training in the shortest time possible, the rowing machine is the answer. Since rowing requires the use of all major muscle groups, including the upper body, the heart and lungs have to work even harder than running and cycling to deliver oxygen to the muscles. This means that the energy expenditure of rowing is comparable to that of running, and greater than that of cycling.
But before going out to buy a rowing machine, two issues must be taken into account. Firstly, the technical challenge of rowing is possibly greater than that of running or cycling, since it is not a skill that everyone has. Although a coach or physical trainer can help us with this, we already mentioned that a good rowing technique should be felt mainly in the legs, not in the arms and back.
Second, since it is not weight-bearing, rowing does not provide the same benefits for bone health as the treadmill, although there is evidence that it may increase bone density to a lesser extent. However, as in cycling, by offering a more joint-friendly option, it is an interesting alternative for those who suffer from joint pain but want to keep their heart and lungs healthy.
It depends on each person's goals, what our current state of health is and, most importantly, what we like the most. The best exercise is the one you do. Therefore, choosing the device that we like the most will increase the probability that we will practice it in the long term.
This article was originally published on The Conversation. Lewis Ingram is Professor of Physiotherapy at the University of South Australia. Hunter Bennett is a Professor of Exercise Science at the University of South Australia. Saravana Kumar is Professor of Allied Health Professions and Health Services Research at the University of South Australia.
