Take a look around at the cardio equipment in your gym and you will see a common theme emerge – for women only. What about the free-weight area? Do you see more men than women? Why is it that women have always been told that to lose bodyfat they must spend countless hours on the step machine, treadmill, or bicycle, while spending little time pumping iron? Women, are you getting tired and bored of stepping and cycling to nowhere? The latest news about fat loss may surprise you and allow you to stop running around in circles. It’s time to update your workout program and redefine your goals using the best information based on scientific research, and not gym-talk. Make a resolution to change your body with a smart, scientific approach, and you’ll see proven results.

A Little Exercise Physiology
First, let’s define some basic terms related to this weight loss topic. The scientific term for weight is mass. The term “body composition” means dividing the body’s mass into fat free mass (FFM), fat mass (FM), and lean body mass (LBM) [1]. FFM consists of the portion of muscle, bone, and organ weight that contains no fat. FM is the total body fat, which includes essential fat and storage fat. Essential fat is required for the body to maintain normal physiological functions. It is found inside organs, bones, and nerves. Women have other forms of essential fat that are sex-specific. The fat in women’s breasts and genitals and lower body are specific to women, but not to men. Some storage fat is necessary to protect both men’s and women’s internal organs from trauma and provide the body with reserve fuel. The other type of storage fat is made up of Oreo cookies and Haagen-Daz ice cream, and is not necessary for life (unless you’re going through a relationship break-up!). When we say that we want to lose fat, that Oreo cookie storage fat is the fat we want to lose. LBM is the amount of FFM and some FM that is essential fat for life. When body composition measurements are taken using skinfold calipers, the results are percentages of FM and LBM. When FM is decreased and LBM is increased, body composition improves favorably, and the body takes on a harder and more muscular appearance with less flab. But don’t worry ladies you won’t look like a “miniature Arnold.”
Now what about that dirty word “metabolism?” People who are overweight love to claim that their body has a slow metabolism and that’s why they can’t lose weight. Well, you know what? They are wrong. The real reason they are gaining weight is that they are not active enough. Fat is biologically inactive tissue. In other words, it doesn’t do anything except sit on the couch with the remote control and keep us warm. On the other hand, muscle is constantly at work, even at rest. It generates and gives off heat and requires energy (calories) to do this. When we are awake, our body needs energy to perform all sorts of activities just to keep us alive. The amount of energy that our body needs for normal physiological functioning while we are awake is called the basal metabolic rate (BMR) [1]. The resting metabolic rate (RMR) includes the BMR plus the amount of energy we use when we are sleeping and waking up from sleep. Our total body metabolism actually refers to our total daily energy expenditure (TDEE) and is a combination of RMR, the thermic effect of feeding (TEF), and physical activity. On the average our TDEE is divided up into approximately 60-75% for RMR, 10% for TEF, and 15-30% for physical activity. Although a certain percentage of our TDEE is genetically programmed, there are some areas that we have direct control over. For example, we can increase our physical activity simply by training longer, harder, or more days per week, and we can increase our RMR by adding more muscle to our body.

Cardio Slows You Down
Now do you see where we are heading? Women usually choose to increase their TDEE by increasing their physical activity through endurance exercise. While that is a scientifically proven method for acute weight loss, it may not be the best method for long-term weight loss. You see, once you start decreasing your FM with endurance exercise, you also decrease your LBM. Since your LBM is directly associated with your RMR, when your LBM decreases, so does your RMR. This means that your body will be using fewer calories at rest now that you weigh less. Translated into gym-lingo, consider that to lose more weight you will have to workout on that stair climber longer or increase your intensity. But as stated earlier, the physical activity component of your TDEE caps out at about 30%. Therefore, a time will come that you hit a plateau and will not be able to lose one more pound without severe calorie restriction. That is probably our least favorite alternative. Enter resistance training. Yes, it is true that you will expend more calories during a typical endurance training session compared to a resistance training session. But, it is also true that you will use more calories throughout the day and even at rest if you have more muscle on your body. To back this up, a study on the effect of habitual exercise on daily energy expenditure and metabolic rate was performed on a group of sedentary, moderately active, and highly active men [2]. Although this study did deal with men, even considering the gender differences, it still has application for women. The researchers wanted to determine if even on a non-training day, the highly active group burned more calories. They found no evidence that habitual exercise, at a high or moderate level, lead to a significant prolonged stimulation of metabolic rate. However, the increased LBM associated with exercise did increase the participants’ daily energy expenditure by 8-14%. So, what is better: burning more calories during one hour of exercise, or burning more calories throughout the day and night? Why do you have to make a choice, ladies? The best answer is to do it all, then you will be on your way to your best body yet!

Variety is the Spice of Life
Many scientific studies can help prove this point. Most recently, a 14-week study at North Dakota State University, Fargo, compared endurance only, resistance only, impact endurance (running, jumping), and resistance, non-impact endurance (bicycling, swimming) on RMR, FFM, and fat loss [3]. Their study showed that the subjects who performed both endurance and resistance training lost an average of 10 pounds of fat and gained 13 pounds of FFM. Best of all, their RMR increased about 380 kcal per day! The non-impact endurance/resistance-training group gained the most FFM and had the largest increase in RMR. This may have been due to the fact that the non-impact endurance exercise did not break down valuable muscle tissue gained during the resistance exercise. Although the endurance training only group lost fat, they also lost FFM and decreased their RMR. A similar experiment performed at the same university also concurred [4]. While resistance training alone can increase BMR and muscular strength, and endurance training alone can increase aerobic power and decrease bodyfat, combined training can provide all of these benefits. Are you getting off the treadmill yet?

No Thanks; I’m On a Diet
What happens when physical activity is increased and calorie intake is decreased? Of course there will be loss of weight, but will the loss come from FM or LBM? A study on resistance weight training during caloric restriction in obese women proved that LBM was preserved [5]. Another study examined the effects of resistance vs. aerobic training combined with an 800 calorie liquid diet on LBM and RMR [6]. These researchers randomly assigned 17 women and 3 men to a group of endurance training for 1 hour, 4 times/week; or resistance training 3 days/week at 10 stations increasing from two sets of 8 to 15 repetitions to four sets of 8 to 15 repetitions by 12 weeks. They found that although the subjects were on very-low-calorie diets, no decrease in LBW was observed in the resistance-trained group. In addition, the resistance-trained group had an increase in RMR, while the endurance trained group had a decrease in RMR.

How High Can You Go?
It might not even be the fact that more muscle tissue increases RMR. A study that compared a strenuous bout of resistive exercise to a bout of steady-state stationary cycling showed that the strenuous resistive exercise resulted in greater excess post-exercise oxygen consumption compared to the steady-state endurance exercise of similar estimated energy cost [2]. There was an increase in the RMR for up to 5 hours after the resistance exercise! This makes a case to incorporate high intensity endurance exercise into a resistance-training program to perhaps tap into the increased RMR after strenuous exercise. As a matter of fact, a study of 33 college age women who performed an aerobic circuit weight training program backs up that assumption [7]. The results from the 45-minute circuit of 30 activities including 5, 3-minute aerobic exercises and 25, 30-second weight training or calisthenic exercises showed that the women improved their cardiovascular fitness, body composition, and muscular strength.

Mixing It Up
So let’s develop a plan, girls. Try alternating cardio and weight days, and even alternate your cardio days into impact and non-impact days. Stop running or stepping for 45 minutes to an hour in a steady state. Cut the session down to 20-30 minutes and raise the level of intensity. You can’t do cardio at the highest intensity possible for an hour. If you can, you aren’t at the highest intensity you can go. An even more effective cardio workout is to interval train. For example, if running, jog at a moderate speed for 1 minute, and sprint for 10-15 seconds. If you are on the treadmill, you may find that you have to subtract the time it takes for the machine to speed up for your sprints. If you are swimming, you can just increase your speed in the water when it comes time to sprint. When on a step machine, simply increase the level for your “sprint” time. On the bike, increase the level or tension.
So now are you ready to mix it up a little in the gym to achieve that tight body you’ve always dreamed of? Designing your training program with some science to back it up will surely blast your body and mind into the new millenium. Just make sure that you are combining your cardio with weight training sessions and you will indeed be training harder and smarter to achieve your new millenium body.

References
1. McArdle, W.D., F.I. Katch, and V.L. Katch, Exercise Physiology. Fourth ed. 1996, Baltimore: Williams & Wilkins.
2. Horton, T.J. and C.A. Geissler, Effect of habitual exercise on daily energy expenditure and metabolic rate during standardized activity. Am J Clin Nutr, 1994. 59(1): p. 13-19.
3. Dolezal, B.A. and D.J. Terbizan, Concurrent impact vs. non-impact endurance and resistance training on RMR. Medicine and Science in Sports & Exercise, 1999. (in press).
4. Dolezal, B.A. and J.A. Potteiger, Concurrent resistance and endurance training influence basal metabolic rate in nondieting individuals. J Appl Physiol, 1998. 85(2): p. 695-700.
5. Ballor, D.L., et al., Resistance weight training during caloric restriction enhances lean body weight maintenance. Am J Clin Nutr, 1988. 47(1): p. 19-25.
6. Bryner, R.W., et al., Effects of resistance vs. aerobic training combined with an 800 calorie liquid diet on lean body mass and resting metabolic rate. J Am Coll Nutr, 1999. 18(2): p. 115-121.
7. Mosher, P.E., et al., Effects of 12 weeks of aerobic circuit training on aerobic capacity, muscular strength, and body composition in college-age women. Journal of Strength and Conditioning Research, 1994. 8(3): p. 144-148.