Training the Female Athlete - The Fat Burning Zone
by Steven Bubel MS, CSCS
|2009 AMA Women's Motocross Champion Ashley Fiolek|
Over the last decade or so, you’ve undoubtedly observed the evolution of the female athlete. Women’s motocross, in particular, has seen a tremendous increase in athleticism, aggression, and speed and this exponential jump in performance has resonated throughout the entire sport. Participation, sponsorship and media coverage are at unprecedented levels and the sport’s popularity is at an all-time high. Indeed, the bonds of tradition have been broken and, with the likes of Sarah Whitmore, Jessica Patterson, and Tarah Geiger leading the way, women continue to push the limits and redefine motocross.
Not to be outdone by their male counterparts, female athletes have also acknowledged the benefit of off-the-track supplemental training with on-the-track performance. Unfortunately, myths, misconceptions, and a general misunderstanding still abound and the bulk of most women’s programs still include a heavy dose of low-intensity cardio and light weight, high-repetition weight training. The fear of leaving their “fat-burning zone” and of getting “big and bulky” has biased women against high-intensity cardio and lifting “heavy” weights, respectively. This weight lifting myth is also perpetuated in the male athlete. Sadly, as we shall see, these unfounded fears have precluded men and women alike from achieving their full athletic potential.
Destroying the Dogma – The “Fat-Burning Zone”
Ask almost any trainer and they’ll tell you that to burn the most amount of fat during exercise you need to perform long-duration, moderate-intensity activities; somewhere between 45 and 60 minutes at approximately 70% of your maximal heart rate (MHR)*. Indeed, research shows that the highest rate of fat oxidation (i.e. “burning”) does occur between approximately 70 and 80% of one’s MHR and that higher intensities depend largely on carbohydrate for fuel. Furthermore, as the duration of the exercise increases(>30 minutes) not only does the number of calories burned increase, so too does the dependency upon fat as a fuel source. In light of these observations, it’s easy to see how the infamous “fat-burning zone” was born.
- To determine your age-predicted maximal heart rate (MHR) simply subtract your age from 220. A 25-year-old athlete would have an estimated MHR of 195 beats per minute (bpm), for example.
|Jessica Patterson came out swinging in the opening round of the 2010 WMA series at Hangtown with a 1-1 sweep
While certainly not incorrect, prescribing exercise based upon this information is a bit misleading. To do so assumes that the number of calories expended during exercise and the source of those calories is vital to improving long-term body composition. Current research, however, suggests that this may not be the case. In comparing a 20-week “endurance” training protocol with a 15-week high-intensity intermittent-training (HIIT) program (i.e. interval training), one study found that, even though the endurance-trained group expended more than twice as many calories (28,800 vs. 13,800) over the course of the study, the HIIT group lost significantly more fat. Yes, you read that correctly. Cycling uninterrupted for 30 to 40 minutes 4 or 5 times a week resulted in LESS fat lost than performing 10 to 15 short (15-30 seconds), all-out sprints. At first glance, this appears to contradict perhaps the most widely accepted principle of exercise prescription yet, subsequent research has supported these original findings. So the question is, how does brief, high-intensity exercise, which burns predominantly carbohydrate for fuel, lead to greater long-term fat loss? The answer lies in what happens after you stop exercising.
Quite understandably, the earlier studies (upon which the “fat-burning zone” is based) examined only the exercise period itself and failed to take into account the number of calories expended in the post-exercise period, which, depending on the severity of the exercise bout, can be quite substantial. Returning the body to its pre-exercise state (i.e. replenishment of energy stores, lactate removal, regulation of body temperature, etc.) requires energy and, as you might now guess, the substrate used to fuel these processes comes from pre-existing fat stores. Intense activities(>80% MHR) such as interval training and weight lifting can result in higher-than-normal fat oxidation that lasts long after exercise has ended. In fact, resistance training has been shown to raise metabolism by 20% for up to 48 hours! Performed 3 or 4 times a week, this “after burn” can add up to tens of thousands of calories over the course of a year. Even if we conservatively estimate the post-exercise expenditure to be in the neighborhood of 150 calories, exercising in this fashion 3 days per week for one year would result in over 23,000 calories expended beyond those burned while exercising. That is the equivalent of nearly 7lbs of fat! In contrast, it appears that the fat-burning benefits of low-to-moderate-intensity activities (<70% MHR) cease almost as soon as you stop working out. If you’re lucky, you might expend an additional 10-20 calories in the post-exercise period, which would add up to a whopping 3000 extra calories or so over the course of a year; less than that contained in a single pound of fat. It is for this reason that women who engage in low-to-moderate-intensity aerobic exercise without performing resistance training (or making changes to their diet) typically experience extremely slow fat loss. To make matters worse, unless you are extremely unfit, this type of training will do nothing to enhance your performance on the track.
Motocross, as you are painfully aware, demands the ability to tolerate extreme cardiovascular overload and lactic acid accumulation with heart rates generally higher than 80% MHR. In one study, researchers simulated a 10-minute moto and found heart rates to range from 155 to 174 beats per minute (bpm). For the average 25 year old, with an age-predicted maximum heart rate of about 195 bpm, this represents 80-90% of their MHR. Taken in actual competition, heart rates can climb to as high as 180-200 bpm (90-100% MHR) and remain there for the duration of the race. To match or exceed this effort, motocross training must be intense, achieving heart rates far beyond the “fat-burning zone.” For women this is especially true since, given slight differences in physiology (i.e. lower hemoglobin levels and blood volume, smaller maximal stroke volume), they naturally possess a slightly diminished ability to perform at such intensities. Fortunately, this gender gap narrows with training.
Now that you are fully aware of the benefits and necessity of high-intensity training (not only for performance but body composition as well), it’s time to learn how to apply it in the real world. The simplest solution is to convert your existing cardio workout into an interval-training program. Interval training, for those not familiar, is simply alternating periods of “maximal” effort(>80% MHR) with periods of recovery and consists of six basic elements:
- Number of repetitions [4-6]
- Number of sets [2-5]
- Duration of work intervals [30-90 Seconds]
- Intensity of work intervals [Maximum Effort]
- Duration of recovery periods between intense work intervals and between sets [30 sec to 2 min.]
- Intensity of recovery periods [Easy]
The numbers in the brackets correspond to the parameters most specific to motocross. As you can imagine, the combinations of work and recovery are limitless and make structuring a program beyond the scope of this article. Just remember, the idea is to challenge the cardiovascular and muscular systems in a way that will be demanded of them in competition. This can be done by running hills, changing the speed and/or incline on a treadmill, mountain biking, taking a spinning class, doing track work, etc. Does this mean that low-intensity, long-duration activities are worthless? Not entirely. Low-to-moderate-intensity activities have been shown to enhance recovery and are still the preferred method for most trainers seeking to improve aerobic capacity (VO2max) in their athletes. This is motocross, though, and not the Tour de France. Train hard.
In conclusion, women have certainly made tremendous strides and they should be applauded for their efforts. But, if they ever hope to compete head-to-head with the boys, or rise above their female competition, their training programs need to evolve. Interval training must become an integral part of those programs. In Part II we will look at an even more powerful (and misapplied) weapon in the woman’s arsenal - strength training.
That's it for now, until next time, good luck with your training and remember, if you have a question, log on to the Virtual Trainer Expert Forum and have your question answered by a panel of experts. In addition, be sure and check out the Racer X Virtual Trainer archive section. Your complete one-stop information zone for motocross fitness.