For many years it has been a well-known fact that if you want to lose body fat you must perform aerobics. Go into any gym and you will see the aerobic equipment packed, but you can always manage to get on the squat racks. That is if someone isn't too busy using the squat racks for barbell curls. However, the question if aerobics truly is the most effective way to lose body fat has not often been challenged. However, there may be methods that could cause faster and greater fat loss than traditional aerobic training. The answer to this question lies in examining the research of traditional aerobic activity.
Exercise intensity has a great deal to do with the whole theory of body fat loss. Higher intensities mean working at a level closer to maximal effort. One reason the aerobic paradigm survived so long is due to the proportion of carbohydrates and fats used during different intensities. Research shows the body decreases the use of fat for energy as exercise intensity increases; however carbohydrate utilization is increased(1). So, common sense would reason, performing lower intensity aerobic exercise would cause a greater loss of bodyfat because more calories are burned from the fat. That is only looking at the small picture.
What researchers are realizing is the post-exercise recovery period may be extremely influential on the overall outcome of a training program. To lose body fat, it is more important to take into account the overall calories expended rather than the amount utilized from fat(1). Research shows when the same amount of calories are burned using high-intensity and low-intensity exercise the amount of body fat loss between these groups was not significant(2). In fact, a study performed by Tremblay et al(3), examined the difference of endurance training (ET) and high-intensity intermittent-training(HIIT). The endurance group performed their training for 20 weeks and burned an average of 120.4MJ per session. The HIIT group performed their program for 15 weeks with an average expenditure of 57.9MJ per session. In other words, the ET group burned more energy during their training sessions. However, the result of six subcutaneous skinfolds showed the HIIT group lost significantly more body fat. There has to be something happening to the body beyond simple caloric expenditure.
What? You say this is one study and that can tell us everything! Fine, here is a couple more. Research by Hickson et al(4), Pacheco-Sanchez et al(5), Bryner et al(6), all demonstrated higher body fat loss from the high-intensity groups than the lower-intensity groups. This is extremely interesting considering the past theory that by working at a lower intensity you will burn more body fat. Even weight training has been shown to be productive in losing body fat. Kraemer et al(7) studied the effects of three different groups, diet, diet and aerobics, and diet, aerobics and weight training. The result? Simple, the group that performed all three programs lost TWICE as much body fat, but the same amount of weight as the aerobics and diet group. This is important because this demonstrates that anaerobic training will spare more lean tissue, which in turn will keep metabolism elevated and make one look overall better. When people generally lose a lot of muscle mass they tend to look soft and flabby, just look at the average aerobics instructor.(above)
Okay, why is the high-intensity group losing more body fat? There are a lot of theories, but no concrete facts. But, with exercise basically everything is still theory and we just try to employ effective methods. Knowing how the body works allows us to manipulate it for better results. One of the more popular theories is that high-intensity exercise will result in greater post-exercise energy expenditure and fat utilization(8). Meaning: you end up burning calories for hours afterward, some believe as many as 16 hours after training. Another theory is the influence of growth hormone(GH). GH is the anti-aging hormone and also is effective in regulating bodyfat. Having a high production of GH is useful in maintaining low body fat levels. The body naturally produces GH in response to high levels of lactic acid. Lactic acid is the burning sensation usually described as the "burn". As described in Kraemer and Fleck's excellent text, Designing Resistance Training Programs, "... this energy source (lactic acid) contributes a moderate-to-high percentage of the energy during activities composed of high-intensity work interspersed with rest periods and high-intensity activities lasting longer than 25 s, such as interval run training and wrestling." So, short rest intervals, 45-to-90 seconds, with anaerobic training lasting at least 25 seconds causes high levels of lactic acid. In turn this would cause a greater production of GH, so in theory, greater body fat loss.
A third theory can be a little more confusing because a little more explanation of exercise physiology is necessary. During the recovery of high-intensity exercise higher levels of free-fatty-acids can be found, or increased use of fat during the recovery period. Rasmussen et al found high-intensity exercise resulted in greater acetyl-CoA carboxylase inactivation, which in English means, an increase utilization of free-fatty-acid oxidation(9). Finally, many studies have also shown that high-intensity exercise controls, or suppresses appetite to a greater degree.
How To Get Started Yourself
Hopefully by now you are beginning to contemplate there might be more effective methods for losing body fat. But, before I describe how to get started there are a couple more myths to dispel about aerobic training. One of the most important myths is the preconception that aerobic training is the only way to improve cardiovascular fitness. Elite Strength Coach, Charles Staley, has written a provocative article pointing out some of the facts of aerobics.(10):
ï¿½ According to IDEA magazine, the average female aerobics instructor has 18% bodyfat. This is higher than the average female competitive weightlifter, 16%.
ï¿½ Dr. Marc Breehl, a top anesthesiologist specializing in cardiac surgery, has said that the enlarged hearts of aerobic athletes are weaker, not stronger than athletes with an anaerobic background. This evidence should prevent any concerns that you won't be doing "cardio", or training your heart.
ï¿½ Todd, Sports Medicine, 14 (4): 243-59, October, 1992 "Circuit weight training has been shown to improve aerobic endurance and muscle strength and to have additional benefits of improved treadmill time compared with traditional aerobics programs."
ï¿½ Boyden, Archives of Internal Medicine, 153 (1): 97-100, January 11, 1993 "In healthy pre-menopausal women with normal baseline lipids, 5 months of resistive exercise training reduced total CHO and the LDL fraction."
ï¿½ McCartney, et al:, American Journal of Cardiology, May, 1991 "There is a much better adaptation to life activity with weight training."
It is important to remember that aerobics and cardiovascular exercise are two completely different terms. Aerobics means training with oxygen, while cardiovascular exercise refers to the function of the heart and blood vessels. It is possible to have great aerobic conditioning while having poor cardiovascular health. In fact, Michael H. Stone has done plenty of research showing the positive cardiovascular benefits of anaerobic training. Stone describes some of the following health benefits of anaerobic training:
ï¿½ "Resistive training may produce positive changes in serum lipids with the volume of training being the dependant factor (11)."
ï¿½ "...weight-training may beneficially alter glucose tolerance and insulin sensitivity (11)."
ï¿½ Using an Olympic lifter style program for eight weeks the following health benefits were found: decrease of resting heart rate by 8%, decreased systolic blood pressure by 4%, lean body weight increased by 4%, and body fat decreased by 6% (12)!
Alright, time to get started. Interval training is a great method of high-intensity training to reduce body fat and help the cardiovascular system. It is especially useful since the body adapts to aerobic type training after 6-8 weeks of training (13). If you have never exercised before you may want to spend some weeks building a base of conditioning so that you can adapt to the high level of intensity. Assuming you have a good base to work from this is a good way to begin.
You will split the workout into a work and rest session. One work and rest session is referred to as an interval. The following table outlines how you may progress through such training. World renowned strength coach, Charles Poliquin uses more than 26 methods, so by no means is this the only way to perform interval training.
Interval Training Program below is a table breaking down how to perform an interval training program. Begin at the top and when possible go to the progressions by going down the table. You may be able to progress workout to workout until you find a challenging level, or you may find the initial setting challenging enough to start with several workouts. Feel free to experiment with the work and rest intervals to find a level that is challenging.
|First Level||30 seconds||3 minutes|
|Second Level||35 seconds||2 minutes 55 seconds|
|Third Level||40 seconds||2 minutes 50 seconds|
|Continue the following||Increase work to 1 minute||Decrease rest to 1 minute|
The speed in which you will go through this progression depends upon your current conditioning level. For example, you should not try to continue through the steps until during the rest time your heart rate drops to 60% of maximum heart rate (220-Age). If you do not reach the 60% mark it means you have not recovered from the work time. You should also not progress until you can perform six intervals. The total duration should not exceed 40 minutes and not more than four days a week. There are many methods in which to perform the interval training, running, biking, etc. One of my favorites for clients is the bike because most people can handle the stress placed by a bike versus running. If you choose to use a bike, keep the revolutions per minute to 60-75 during the work time.
The idea that aerobics may not be ideal for losing body fat may be hard for most to accept. However, try it; see if there is a difference. Other people, including many professionals, will argue with these ideas, but how do you argue research and real world results?
1. Coyle, E.H. Fat Metabolism During Exercise. [Online] Gatorade Sports Science Institute. 1999, March 25.
2. Ballor, D.L., J.P. McCarthy, and E.J. Wilterdink. Exercise Intensity Does Not Affect the Composition of Diet- and Exercise- Induced Body Mass Loss. Am. J. Clin. Nutr. 51:142-146, 1990.
3. Tremblay, A., J. Simoneau, and C. Bouchard, Impact of Exercise Intensity on Body Fatness and Skeletal Muscle Metabolism. Metabolism.43:814-818, 1994.
4. Hickson, R.C., W.W. Heusner, W.D. Van Huss, D.E. Jackson, D.A. Anderson, D.A. Jones, and A.T. Psaledas. Effects of Dianabol and High-intensity Sprint Training on Body Composition of Rats. Med. Sci. Sports and Exercise. 8:191-195, 1976.
5. Pacheco-Sanchez, M., and K.K. Grunewald. Bodyfat Deposition: Effects of Dietary Fat and Two Exercise Protocols. J. Am. Col. Nutr. 13:601-607, 1994.
6. Bryner, R.W., R.C. Toffle, I.H. Ullrish, and R.A. Yeater. The Effects of Exercise Intensity on Body Composition, Weight Loss, and Dietary Composition in Women. J. Am. Col. Nutr. 16:68-73, 1997.
7. Kraemer, W.J., et al. Influence of Exercise Training on Physiological and Performance Changes with Weight Loss in Men. Med. Sci. Sports and Exercise. 31:1320-1329, 1999.
8. McMillan, J.L., et al. 20-hour Physiological Responses to a Single Weight-training Session. J. Strength Cond. Res. 7(3):9-21, 1993.
9. Rasmussen, B.B., and W.W. Winder. Effect of Exercise Intensity on Skeletal Muscle Malonyl-CoA and Acetyl-CoA Carboxylase. J. Appl. Physiol. 83:1104-1109, 1997.
10. www.myodynamics.com. Re-examining the Value of Aerobic Exercise Part II. October 5, 1996.
11. Stone, M.H., S.J. Fleck, N.T. Triplett, and W.J. Kraemer. Health-and Performance-Related Potential of Resistance Training. Sports Med. 11(4): 210-231.
12. Stone, M.H., et al. Cardiovascular Responses to Short-Term Olympic Style Weight-Training in Young Men. Can. J. Appl. Sport Sci. 8(3): 134-9.
13. Charles Poliquin, "Training and Eating for Maximum Fat Loss Seminar" December 11, 1999.