What you need to know about cardio

So cardio...What is cardio, exactly? It's not just running, or biking, or what have you. Cardio is cardiovascular activity, which is aerobic activity, which basically means "in the presence of oxygen." So, cardiovascular activity requires intake of oxygen, which pumps your heart/blood, and so on. Moving on.

There are different mechanisms to cardio activity, and it's tough to find the optimum way to do it. It takes up to 15 minutes before you body gets into its "fat burning" mode, but if you work too long then your body will start to eat its own muscle. I'll outline the "classes" of cardio, which are divided by the amount of work required to perform them.

LOW ACTIVITY: the plus side to low activity is it burns a higher percentage of fat for each calorie burned, but the downside is it won't burn as many calories. So you might work for 30 minutes, burn 200 calories, and each calorie you burn is 80% fat. That's a good deal of fat! But, again, not burning a lot of calories. This type of exercise is great if you want to burn fat, you don't want to sacrifice muscle, and you aren't on any serious time constraint. Low activity would be defined by a heart rate of around 60-65% of your maximum (you'd need a doctor, a quick tutorial, or heart rate monitor to figure this out exactly). Some examples might include: brisk walking, slow and steady biking, etc.

HIGH ACTIVITY: the plus side to high activity is it burns more calories and it is very heart-healthy, but the downside is you will burn more muscle than you would with low activity. Drawing from the previous example: you might burn 400 calories in 30 minutes of hard work, but each calorie burned is only 60% fat. What this would mean is you'd lose a lot more weight, but a good deal more of that weight is your hard-earned muscle. This is why lots of people who run often, and have an average or even decent diet, still have some flab. This is characterized as a heart rate that is 70-75% (or more) if your maximum heart rate. Some examples would include jogging, cycling, swimming, etc.

HIGH INTENSITY INTERVAL TRAINING (HIIT): this is the toughest form of cardio to do, but it contains the best of all worlds. If you want to burn the most fat, and the most calories, then this is your poison. First the outline of HIIT: it's a structured interval workout where you work as hard as you can for a specified amount of time (usually 30-60 seconds), and then you work at a very slow rate for a specified amount of time (usually 30-120 seconds), and you alternate. So an example would be: walk as a warm up for 5 minutes, sprint for 60 seconds, walk for 60 seconds, and continue the sprint-then-walk intervals for 20 minutes, then cool down by walking for 5 minutes. That's a 30 minute workout. HIIT will burn as many (or more depending on how hard you work) calories as high activity workouts, and it won't sacrifice as much fat. The science behind it is this: working as hard as you can works your body in its carb-burning zone. That basically means it aims to eat stored fat. However, no one can work in their carb-burning zone for too long as it requires an all-out spring of energy. Thus, you work for small periods of time in a single setting. This will also rev your metabolism up for a longer period of time (many hours) after you're done with the workout.

The rule of thumb to remember about cardio is also this (except for HIIT as previously mentioned): for however long you work out, that's how long your metabolism is going to be revved up for. If you run for an hour, then your metabolism will remain at unusually high rates for an hour after the workout. That's a good thing!

I think that's it regarding cardio for now.