All exercise is the same, right? Not so fast, suggests a small study of teens out of Scotland that found that high-intensity exercise may be better than endurance training for preventing cardiovascular disease because it can be done in less time.
The study included 57 adolescent schoolchildren (47 boys and 10 girls) who were randomly assigned to high-intensity or moderate-intensity exercise groups.
Both groups did three exercise sessions a week for seven weeks. The high-intensity group’s program consisted of a series of 20-meter sprints over 30 seconds, while the children in the moderate-intensity group ran steadily for 20 minutes.
By the end of the seven weeks, teens in the moderate-intensity group had completed a total of 420 minutes of exercise, compared to 63 minutes for those in the high-intensity group. Estimated total energy expenditures per child were 4,410 kcal for those in the moderate-intensity group and 907.2 kcal for those in the high-intensity group.
Both groups of children showed significant improvements in cardio-respiratory fitness, blood pressure, body composition and insulin resistance. But the teens in the high-intensity group achieved those health benefits with only 15% of the exercise time put in by those in the moderate-intensity group.
The findings, published April 5 in the American Journal of Human Biology, suggest that brief, intense workouts offer a time-efficient way to reduce cardiovascular disease risk factors in teens, said study author Duncan Buchan, of the University of the West of Scotland, and his colleagues.
However, further research is needed, they added.
I am so sick of clients doing excessive cardio – I mean mindless long runs, or bouts on the bike or eliptical. I hear about clients doing 60 minute cardio sessions and they are stiff as a board and in pain. The part that ‘kills me’ is that they won’t stretch or even listen to me when I talk to them about doing some weight lifting. I know cardio is one fat burning strategy, but it is time consuming and the reality is that aerobic activities burn far fewer calories than you think. After doing 20-30 minutes of cardio you may feel as though you’ve burned 600 calories but the cold reality is far different. For example, researchers measured the number of calories burned when walking versus running. The study showed that the average man burns just 124 calories when running a mile and only 88 when walking the same distance. So by running three miles you can expect to burn about 396 calories and by walking three miles you will burn about 240.
Figures for other aerobic activities are shown below (these are calculated using a man who weighs 190 pounds).
• Stationary bike (light): 474 calories per hour;
• Walking uphill (3.5 miles per hour): 518 calories per hour;
• High impact aerobics: 604 calories per hour;
• Stationary bike (moderate): 604 calories per hour;
• Jogging (light pace): 604 calories per hour;
• Running (5 miles per hour): 690 calories per hour;
• Stationary bike (vigorous): 906 calories per hour;
To lose one pound of body weight – you have to burn calories through exercise activity, or decrease your intake of food calories by approximately 3,000 calories. One strategy I use is to decrease 250 calories of food daily and increase your activity by 250 calories per day to reach the 3,000 calorie mark each week to lose a pound a week. Make sense? Do 30 minutes of cardio (intervals = sprints) to burn body fat and then do some weight lifting to build muscle which automatically burns more calories during rest. Or you can combine cardio + resistance. That’s what I personally do.
Too much aerobic exercise will burn calories from fat but can burn fuel from muscle cells—resulting in a loss of muscle mass—now you are screwed. The reason this happens is that periods of aerobic exercise cause the body to shift into survival mode. In this state, it strives to preserve access to fat cells by also burning fuel derived from muscle cells. It does this because the body is incapable of understanding our motivation for doing cardio. As far as it is concerned, it just needs to maintain fat reserves for any pending emergency situations where we might not have access to food.
By combining your workouts with resistance + cardio activities, you can burn up to 44% more calories. The bottom line is that resistance + cardio workouts burn considerably more calories and fat than ordinary cardio alone.
Just tell me what you like to do and I can turn any of your activities into a cardio + resistance workout. For example, if you like to walk or jog you can pick up a set of dumbbells, some ankle weights or even a weight vest. If biking is your thing, just kick up the resistance. Whatever cardio activity it is that you like to do, I’ll show you how to add some resistance and not only will you burn more fat but you’ll also be able to maintain more of your hard-earned muscle mass.
Come in for a few sessions and I’ll teach you how to do a cardio + restance workout. This will help you lean out!
Karvonen heart rate calculation is a better way of determining your optimum heart rate for training.
Most people are familiar with the quick and easy way to determine your training heart rate, which is often stated as:
65-80% of (220 – your age in years)
The Karvonen formula however is a different way of calculating your training heart rate based not on a percentage of your absolute heart rate, but on your heart rate reserve – ie the amount of capacity your heart has to do work above and beyond its resting work rate. The formula is given as:
Target heart rate = [(max heart rate ? resting heart rate) × %intensity]
+ resting heart rate
To calculate your heart rate reserve, you need to know your age (you should know this!), and your resting heart rate. Suppose your resting heart rate is 60 beats per minute (bpm). Your maximum heart rate is still calculated as 220 – your age ie 184bpm. But your heart rate reserve is now given as the difference between resting and maximum heart rate, or 184 – 60bpm = 124bpm.
If you work at 75% of your heart rate reserve, you’ll be training at 75% of 124bpm over and above your resting heart rate ie 93bpm above 60bpm, which is 153bpm. At 80% of heart rate reserve, it’s 80% of 124bpm over and above resting heart rate, which is 99bpm above 60bpm or 159bpm. Your 75-80% training zone therefore is 153bpm – 159bpm.
Although it’s slightly more complex to apply, the Karvonen formula more accurately reflects the working % of your maximum oxygen uptake than does a simple % of max heart rate calculation, particularly for fitter people. So for example, you’re much more likely to be working at 75-80% of your maximum aerobic capacity at 153-159bpm than you are at 138-147bpm, which is the figure you get doing it the simple method based on maximum heart rate only described at the top of this page. This is why Karvonen calculated training heart rate zones are often preferred to simple max heart rate calculations in those who train regularly and who are seeking a more accurate estimation of their ideal training heart rate.