It's widely believed that in order to lose weight you need to exercise for hours on end, however this isn’t necessarily the case. A workout of just 20 minutes could see you burning as many, if not more, calories than an hour-long session. It’s not all about how long you exercise for, but the intensity at which you’re training.
Low intensity training causes a gentle and gradual increase in the heart rate and can be maintained for a longer period of time. This type of training is called aerobic exercise, which is when the muscles are able to receive amples of oxygen from the blood.
High intensity training raises the heart rate quicker and higher than low intensity training. It cannot be sustained for a great amount of time and often results in anaerobic exercise. This is when the body is exercising at such a rate that the blood stream cannot supply the muscles with enough oxygen. When the muscles are working without oxygen, lactic acid builds up, which creates the burning sensation you often feel when training hard.
According to The Biggest Loser's Commando, "Time, distance, weight and resistance can all contribute to making an exercise high intensity. Basically, it's the more work you do in the shortest period of time." In order to get a rough idea of the intensity of your session, the Commando suggests the following equation:
Weight x distance ÷ time = work capacity
For example, a 75kg person who does a 3k walk in 30 minutes would be: 75 x 3 ÷ 30 = capacity of 7.5
Or if they run the same distance in 20 minutes it would be: 75 x 3 ÷ 20 = capacity of 11.25
So the higher the figure, the more intense the session.
Interval training
Interval training mixes bursts of high intensity training with low intensity periods of recovery. For example, you give it your all for a short period of time, say about 15 seconds, and then allow yourself a recovery period – an ‘interval’ – of more gentle exercise for 1 or 2 minutes. You then repeat this process as many times as recommended. An intense workout like this wouldn’t normally last much more than 20-30 minutes, which may not sound like much, but do it correctly and you’ll know about it.
Due to this combination of different levels of intensity, interval training gives you the benefits of both aerobic and anaerobic training within the same workout. Sydney-based personal trainer Roza Bacelas says, “During the high intensity, short bursts, your anaerobic system is working and during recovery or the low intensity interval, your aerobic system is in control.”
This is not only a great way to improve your cardiovascular fitness levels, but it also aids weight loss. While low intensity aerobic training has long been thought of as the best fat burner, high intensity interval training could also help you shed the kilos. By working harder you can burn as many, if not more, calories during a shorter space of time and also after the actual training session.
Roza explains, “The benefits of intense interval training come after the training has finished. Due to the metabolic boost, more calories and fat are burned for a period following the workout. This after-burn or EPOC (Exercise Post-Oxygen Consumption) means our bodies expend calories trying to get the body back into its pre-exercise state.”
Count the beats
With time and distance changing from one interval workout to the next, your heart beat is a steady indicator of your performance. Professional football player and personal trainer Kevin Barrett says, “By monitoring your heart rate you can see how hard you’re working as the higher it is, the more intense the workout.”
Firstly you need to calculate your maximum heart rate; simply minus your age from 220 for a rough indication. For example, a person of 30-years-old would be 220 – 30 = maximum heart rate of 190, or thereabouts. Low intensity exercise works at about 60-65 percent of your maximum heart rate, while high intensity exercise works at 75 percent and over.
It’s also important to monitor your heart rate during the intervals. Kevin says, “The quicker your heart rate slows down during the recovery period, the fitter you are. You should find that the more interval training you do, the sooner your heart rate will get back to its normal state.”
If you think you're ready to try a high intensity session, follow one of the interval workouts in this week’s challenge to get your heart racing and body pumping.