Increase weight loss by working out less?

Really? -
Judging from the ever rising overweight/obesity rates in the United States, I think it's safe to assume that a majority of Americans subscribe to the work out less plan. I find it a bit alarming when scientific data is released and the news takes a portion of a study's findings out of context and reports on it. Typically we can end up misguided and confused. That's why it's so important to understand the bigger picture surrounding "sound bites" like this post's title. This reminds me of a radio ad that would, ironically, air while I was training at the gym.  The advertisement was pushing a diet pill which promised weight loss without the "unhealthy stress and strain of exercise"! I'll spare you a rant, but I will say that the ad was eventually changed so that it did not include the word unhealthy.  Calling exercise unhealthy is blatantly inaccurate. Yet, unfortunately this isn't obvious to everyone. But I digress...

What's going on? -
Saying that we can increase weight loss by working out less is ambiguous because this statement tells only part of the story. So, before you scratch that workout off your to-do list, please read on. According to a study published in the American College of Sports Medicine's (ACSM) Journal of Medical Science and Sports Exercise, it's possible to burn more calories and spend less time working out. However, the key to this result lies in how intensely you workout. Before I go on, it might be helpful to recall the caloric balance equation and its role in weight maintenance, and you can read more about this in a past post found here.

Image from CDC website

Consider a typical day of food consumption and energy expenditure. Simply put, if calories eaten exceed calories burned, we end up with a calorie surplus for that day and over time this leads to weight gain. On the other hand, if we burned more calories than we ate, than over time this leads to weight loss. If  calories in are equal to calories out, the scale is in balance and weight is maintained. Another thing to keep in mind is that we are always expending energy, even while we're resting.


Back to the study - The researchers wanted to see what the energy expenditure at rest of males, aged 22 to 33, would be on a day when they performed a vigorous indoor cycling exercise bout vs. on "a controlled resting day" when they performed no exercise at all.  I underlined and bold faced the word vigorous because this is very important to note. In this case vigorous exercise is defined as performing a physical activity at a level that causes you to be too out of breath to talk. Working out at this intensity level "resulted in a significant [emphasis added] elevation in post exercise energy expenditure, that persisted for 14 hours" after the exercise bout ended (ACSM).


Wow! This sheds some much needed light on that rather ambiguous statement that implies we can increase weight loss by working out less. Now we understand that it's possible to decrease the amount of time we spend working out, but this must be accompanied by an increase in the intensity of our workout to a vigorous level. This is because the research suggests that we can burn additional calories above and beyond what we burned during the workout, even while we're at rest! This is sometimes referred to as caloric after burn.

Here's the data: During the vigorous cycling bout these guys expended 520 calories (kcal).  This isn't surprising because we all know exercise expends calories. We also know that vigorous exercise burns more calories than low and moderate intensity exercise. However, what is really exciting is that after the men finished exercising, and with their post exercise activity level restricted and monitored, they continued to  burn an additional 190 calories (kcal)  during the 14 hours after their workout, as compared with control days when the men were inactive. "The 190 calories burned after exercise above resting levels represented an additional 37% to the net energy expended during the 45-min cycling bout." 

Bottom Line - 
The study's test subjects were young men, so the results may not be the same for women, or for an older population.  Also, we might not be able to workout at a vigorous level for 45 minutes. Given this and other studies on vigorous intensity exercise which show the added benefit of caloric after burn, it seems beneficial to try to incorporate little bouts of vigorous intensity exercise in our workouts. But if you've never exercised, or haven't worked out in years - BEGIN SLOWLY and always consult your physician before beginning any exercise program. Obviously any exercise is better than none, but I like the idea of putting in a little more effort, giving it a little less time and reaping bigger rewards from my workout.  It seems like a win/win to me and that's no sound bite.

In the next post there will be some suggestions for vigorous intensity bout exercise programs and also a discussion relating to another study that shows bouts of vigorous intensity exercise have been shown to be beneficial in reducing inflammation in overweight and obese men. Chronic inflammation is linked to all kinds of health problems.

In the meantime, keep moving! 

Sources
CDC - http://www.cdc.gov/obesity/data/trends.html
ACSM - American College of Sports Medicine - http://journals.lww.com/acsm-msse/Abstract/2011/09000/A_45_Minute_Vigorous_Exercise_Bout_Increases.6.aspx
CDC - http://www.cdc.gov/healthyweight/calories/index.html
chronic inflammation -  http://www.drweil.com/drw/u/ART02012/anti-inflammatory-diet

Am I burning fat? Aerobic exercise & energy use

Now that we have a general understanding of the energy balance equation which was discussed in last week's post found here, let's focus on how this all relates to something commonly referred to as the fat burning zone. You may have seen this zone, along with the cardio zone, illustrated on the treadmills, elipticals or aerobic exercise heart rate charts at your fitness center or gym. These zones are based on aerobic training principles and in theory are true, but in application can be somewhat misleading.

Basic Principles of Fitness Training-

If one of your fitness goals is to lose weight, you might be thinking that the fat burning cardio workout listed on your treadmill is the way to go. However, before we look at the fat burning zone specifically, I want to highlight a few basic principles of fitness training first. In order to put together an effective exercise program we need to address:

1. Overload - Overload is the amount of stress or demand that we put on our body during exercise. In order to improve our level of fitness we need to challenge our bodies during our workouts by increasing our level of effort. The amount of overload effects the level of intensity of our workouts and this in turn influences the improvements in our fitness level. If we work out too easily we are likely to see little change in our fitness level, whereas too much overload can lead to injury or burn out.(3)
2. Progression - The human body has the amazing capacity to adapt to the demands of exercise by improving its functioning. Because of this ability it is essential to make changes to your workout after you notice that the current level you're working at is becoming too easy. This isn't always a simple assessment, nor is it something many people want to do.  We get comfortable with a routine, so it is easy to become complacent.  This is why many people plateau, or find themselves at a point where they see little to no change in their fitness level (3).

Now that we understand two core principles of fitness training, we need to know how to apply them. When putting together a workout we now know that we must consider the amount of overload needed to maintain or improve our particular level of fitness and for a specific fitness component.  In this post, for example, we're looking at improving our cardiovascular fitness level and body composition by doing aerobic exercise. In order to address the progressive overload principles we must consider 4 areas that are represented by the acronym FITT, which stands for:

• Frequency (how often we perform the activity)
• Intensity (how hard we are challenged by the activity)
• Type (mode of activity)
• Time (how long/duration of the activity) (4)

I prefer the acronym FITTER - which adds Enjoyment and Rest into consideration as well. Adherence to an activity is more likely if it is enjoyed. Arguably more important is the balance between exercise and rest. Too much of a good thing is possible with exercise.  Having said that, over training is something I rarely see.  In fact, the opposite is more often the case.

So, at this point you might be wondering what all this has to do with the fat burning zone. Well, what the fat burning zone is referring to is the level of intensity, along with the amount of time an aerobic activity is performed at, and the macronutrient (fats, carbs, proteins) energy sources used by the body to accomplish the task. By the way, if you're curious to know what exactly constitutes an aerobic workout you can read more here, and if you'd like to catch up on our discussion of energy sources from last week you can find that here.  Now, this bring us to the three energy systems utilized by the body during physical activity. 

Physical Activity and the Three Energy Systems-

As discussed last week, in order to function our bodies need energy in the form of food. We get this fuel from the carbs, fats and proteins found in what we eat and drink. However, the amounts of  these macronutrients the body uses for energy vary depending on the type of activity we're performing.

1. For immediate, explosive energy needs the body uses the immediate energy system. This system fuels activities that last for about 10 seconds or less.
2. For high intensity acitivities lasting for about 10 seconds to 2 minutes the body uses the nonoxidative (anaerobic) energy system. 
3. For any activities lasting longer than 2 minutes the oxidative (aerobic) energy system kicks in. (3)
   

It's important to note that the body typically uses all three energy systems when we exercise, or in activities of daily living (3).  "The intensity and duration of the activity determines which system predominates" (3). For example, if you're running late and walking quickly to catch the bus you're using the oxidative energy system. But if the bus pulls up and you need to sprint to catch it, the other systems become important because the oxidative energy system isn't able to supply energy fast enough to sustain this high-intensity effort.

Modified Borg Rate of Perceived Exertion Scale
Image from ACE

Fat Burning Zone and Exercise Intensity-

So, back to the fat burning zone... The wisdom behind this zone is that if you're exercising in a target heart rate range (read more about this here) of between 50-60% of your maximum heart rate (MHR) (4), or a level 3-4 on the on the modified Borg Rate of Perceived Exertion (RPE) Scale shown at left, (more about that here) you will be utilizing more of the oxidative system, which draws more energy from the body's fat stores.  While this is true, it's just part of the picture.

 Let's look at an example taken from research done at the University of Wisconsin at LaCrosse.  "A 160 pound male walks at a pace of 3.5 miles per hour. At this pace 40% of his energy is supplied from fat sources and 60% from carbohydrate sources.  On another day the same subject runs for 30 minutes at a pace of 6.5 miles per hour.  At this faster pace (higher intensity exercise), 25% of his energy is supplied from fat sources and 75% from carbohydrate sources" (7). Clearly, this would seem to validate the theory that lower intensity exercise utilizes a greater percentage of fat for energy.

However... Please hang in there for a little math, because this will distinctly illustrate the key point I'm attempting to make. "At the 3.5 miles per hour pace the subject burned a total of 240 calories during his 30 minute walk. He therefore burned 96 total fat calories (40% of 240 calories = 96 calories). At the 6.5 miles per hour pace, the same subject burned a total of 450 calories during his 30 minute run. Therefore, he burned 112 total fat calories (25% of 450 calories = 112 calories), which exceeds the number of fat calories burned during the lower intensity exercise session" (7). Not only did this study subject ultimately burn more fat calories, but he was able to burn more total calories overall working out at the higher intensity level for the same amount of time.

The bottom line-

Remember the energy balance equation? Calories in = calories out. When it comes to changes in body composition and weight loss, clearly higher intensity exercise is a better zone to shoot for because it burns more calories than the lower intensity so-called "fat burning zone". That being said, it is important to keep in mind your level of fitness. Obviously, if you're just beginning an exercise program you want to start at a lower intensity and build up gradually. This is where the progression and overload we talked about earlier comes into practice.  With all this talk about burning calories, let's not forget the impact that a healthy nutrition plan has on the "calories in" part of the energy balance equation. Armed with these fitness tools and knowledge, you're closer to achieving your weight loss goals and better health. 


Sources
(1) Whitney, E., Rolfes, S., Understanding Nutrition 11th ed., Thomson Wadsworth
(2) http://en.wikipedia.org/wiki/Metabolism
(3) Fahey, T., Insel, P., Roth, W., Fit & Well: Core Concepts in Physical Fitness and Wellness, 6th ed.
(4) IDEA Fit - http://www.ideafit.com/fitness-library/comparing-intensity-monitoring-methods-0
(5) American Council on Exercise (ACE) -http://www.acefitness.org/
(6) American Heart Association on body composition -http://www.americanheart.org/presenter.jhtml?identifier=4489
(7) Wescott, W.,  What is Fat Burning Zone?
(8) Hoeger, W. K., Hoeger, S. A., Lifetime Physical Fitness and Wellness: A Personalized Program 

Aerobic exercise: How hard should I work out?

"How hard should I be working out?" This is one of the most common questions people ask me during fitness training. This is a good question and the answer is different for everyone. This is because an individual's exercise intensity level, or how hard they need to be working, is directly related to things like their fitness level, age and health. Everyone should ask themselves this important question before beginning an exercise program and when reassessing a current workout. Knowing your exercise intensity level is important in determining how best to bring about improvements in your health.

You may have heard the expression "in the zone" with regard to exercise intensity. This can be used to describe target heart rate (THR) training levels which are benchmarks that are measured during aerobic exercise. You may have seen this range visually depicted in a chart on your gym's treadmill control panel. Some use the misleading phrase "fat burning zone", more on this later, where others just say training zone. In any case, the theory of training in a target heart rate zone can seem a little perplexing.

Adding to the confusion, especially for women, is the emerging scientific data about a gender specific formula for maximum heart rate, which directly impacts how a woman knows if she's in "the zone." Additional information is available here, but before we get into that let's take a look at several factors that are helpful in determining whether or not you're working hard enough during your aerobic workout.

What is an aerobic workout? When we perform aerobic exercise, or aerobics as coined by Dr. Kenneth Cooper way back in 1968, we are increasing our need for oxygen by performing an activity that engages the larger muscles of the body.  This sustained activity, in turn, causes the heart and lungs to work harder than when the body is at rest in order to provide more oxygenated blood to fuel the working muscles (1). There are many health benefits to aerobic exercise (3), and the Mayo Clinic lists ten of them here.  One reason we are focusing on in this post is heart health. 

Heart rate or pulse is the rate at which blood is squeezed out of the heart per minute (BPM). We can use our heart rate to measure how hard our heart is working at rest or during aerobic exercise. This can be done by taking a pulse or heart rate and determining our BPM number. Pulse points are places where an artery passes close to the skin and makes it easier to feel blood pulsing through it. There are several pulse point locations on the body, but 2 of the more commonly used sites are found on the wrist (radial pulse), or on the neck (carotid pulse).

Once you've found your pulse, count the number of times you feel the blood pulsing under your fingers for 10 seconds. Then multiply that number by 6 and you will have your heart rate for one minute. For a more precise measure, you can also use a blood pressure monitor that counts your pulse for you. To learn more about manually taking your pulse, just follow the link here to the Cleveland Clinic's website.

Resting heart rate (RHR) is another useful indicator of heart health. This is the number of times our heart beats per minute while we aren't engaging in any activity and is best taken in the morning before we get out of bed (3). I suggest measuring it for 3 mornings and then taking the average. According to the National Institutes of Health, a normal RHR range is:
Newborn infants - 100-160 BPM
Children 1 to 10 yrs. - 70-120 BPM
Children over 10 and adults (including seniors): 60-100 BPM
Well-trained athletes - 40-60 BPM (5)

Maximum heart rate (MHR) - Knowing your MHR will help you in calculating your target or training heart rate (THR).  The gold standard for determining your MHR is to take a doctor supervised treadmill test. However, for many of us this may not be practical, so exercise physiologists have developed several formulas to help estimate MHR.  One of these is called the estimated maximum heart rate formula:

MHR = 220 BPM - age

At the beginning of this decade, research conducted on the estimated MHR formula found that it "underestimated MHR in older adults" (7). These scientists proposed a new MHR formula:

MHR = 208 - 0.7 x age

This year, more recent research has found that this formula overestimates the MHR for age in women, especially those over the age of 35. See footnote (8). As a result of this finding a new gender specific MHR formula is being proposed, however it is not yet being used in a clinical setting because the research is considered preliminary. The gender specific formula is:

MHR = 206 - .88(age)

After we have determined our MHR we can calculate our training heart rate.


Training heart rate (THR) and finding the right intensity for you - THR is the desired heart rate range which will provide us with the most benefit from our aerobic workouts. Calculating a THR zone helps us determine the level of sustained exercise intensity that best challenges our heart and lungs safely. When calculating THR, I prefer to use the Karvonen or Heart Rate Reserve Formula.  This formula is more personalized because it factors in the resting heart rate (RHR) to determine heart rate reserve (HRR). The formula for calculating HRR is:

HRR = MHR - RHR

Now we move to the next step in determining THR. We multiply HRR by the desired training intensity range at which we want to workout. The American College of Sports Medicine recommends healthy adults exercise at a range beginning at 55% and up to no higher than 90% of MHR.

Let's put all this information into practice. A 30 year old healthy female who has a RHR of 70 and is of average fitness level wants to determine her THR zone.  Here is how she would calculate her THR range:
Begin by calculating MHR. Using the new gender specific MHR formula -
MHR = 206 - .88(age)
179.6 = 206 - 26.4
MHR = 180
Next we determine HRR using the formula HRR = MHR - RHR
HRR = 180 - 70
HRR = 110
Now we plug the HRR number into the rest of the Karvonen equation to determine the THR range.  We begin with the lower end of her training range (light to moderate) or 65%.
THR = 110 x .65 + RHR
THR = 71.5 + 70
THR  lower range = 141
Now we find the THR for our sample female of average fitness level at the top end of her training range (moderate to vigorous) or 85%.
THR = 110 x .85 + 70
THR  higher range = 164

So, this individual would monitor and strive to maintain for the duration of her aerobic activity a target heart rate zone between 141-164 BPM.  These numbers would be adjusted as her fitness level changed.


How much aerobic exercise is enough?   According to the American College of Sports Medicine healthy adults under the age of  65 should shoot for at least 30 minutes of aerobic activity, 5 days a week.  The Center for Disease Control (CDC) suggests healthy adults get at least 150 minutes of moderate intensity or 75 minutes of vigorous intensity aerobic activity per week. This activity should be sustained for bouts of at least 10 minutes. For even greater health benefits the CDC urges us to shoot for 300 minutes of moderate intensity or 150 minutes of vigorous intensity aerobic activity per week, or an equivalent mix of both, again in bouts of at least 10 minutes.

What's light, moderate or vigorous intensity activity?  According to the CDC, "moderate intensity means "you're working hard enough to raise your heart rate and break a sweat." Examples would be:

• walking fast
• doing water aerobics
• riding a bike on level ground or with few hills
• playing doubles tennis
• pushing a lawn mower (CDC)

Vigorous intensity aerobic activity means "you're breathing hard and fast, and your heart rate has gone up quite a bit" (CDC). Examples include:

• jogging or running
• swimming laps
• riding a bike fast or on hills
• playing singles tennis
• playing basketball

So, having plowed through the formulas and worked through the calculations, we now know how to determine our THR zones.  As important and useful as this information is, it should be noted that it is all an estimation.  One research study found that when monitoring aerobic exercise in a group setting, perceived rate of exertion, or how the person exercising is feeling, was as good an indicator of training intensity as THR calculations.  Plus, the exercisers didn't have to stop to take their pulse. Whatever method you choose to monitor your exercise intensity,it is always best to work within your comfort level and not to exceed 90% of your MHR because of increased risk for injury.

The short video below from the American College of Sports Medicine's Exercise is Medicine Library talks more about using Rate of Perceived Exertion as a way to monitor THR. The take away from all of this is to just get moving because exercise really is good medicine.

Don't forget: It is important to check with your physician before beginning any exercise program. Next post will take a look at the misleading concept of the fat burning training zone, and will be much shorter I promise!

Sources
(1) http://en.wikipedia.org/wiki/Aerobics
http://www.google.com/dictionary?aq=f&langpair=en|en&q=aerobic&hl=en
(3) http://www.mayoclinic.com/health/aerobic-exercise/EP00002/NSECTIONGROUP=2
(4) http://www.americanheart.org/presenter.jhtml?identifier=4701
(5) http://www.nlm.nih.gov/medlineplus/ency/article/003399.htm
(6) Physical activity & health: an interactive approach, Thomas, D.Q., Kotecki, J.E.
(7) Tanaka et al., Age predicted maximal heart rate revisited http://content.onlinejacc.org/cgi/content/full/37/1/153
(8) St. James women take heart study http://circ.ahajournals.org/cgi/content/full/108/13/1554 
American College of Sports Medicine
Centers for Disease Control

Women, heart disease and new max heart rate formula

When it comes to women's healthcare, females are typically treated like smaller versions of males.  We women know we aren't "mini-me's" of men, but a patriarchal society hasn't been as quick to recognize this fact. Thankfully, the emerging science of gender based biology is proving what women already knew to be true. We are different. Here's a sampling of the gender differences research is revealing at the system, organ, tissue and even cellular levels:

1. "3 out of 4 people who suffer from an autoimmune disease (such as rheumatoid arthritis, lupus and multiple sclerosis) are women" (1);
2. women are 2 times more likely than men to be diagnosed with thyroid diseases (1);
3. 2-3 times more likely than men to suffer depression (1);
4. 2 times more likely than men to contract gallstones (1);
5. more likely than men to suffer a second heart attack within the year after their first heart attack (1);
6. women who smoke are up to 70% more likely to develop lung cancer than men who smoke (1);
7. 80% of  people affected by osteoporosis are women (1);
8. women are more like to suffer migraines than men (1)
9. a woman's liver metabolizes alcohol and drugs less efficiently than a man's liver (1);
10. a woman's heart is one third the size of a man's heart and beats faster (1);
11. woman wake up faster from anesthesia after surgery (1);
12. a woman's brain is neurologically different from a man's brain (1);
13. a woman's heart responds to high blood pressure by developing thicker walls which puts them at greater risk for heart failure than men (4).

Clearly, the contrasts between the sexes go way beyond the basic XX and XY chromosomes and our reproductive capabilities. Unfortunately for women's health, prior to the 1990's men were the model on which medical research was conducted. An example of this is the practice of pharmaceutical companies testing their new drugs only on men. The exclusion of women and minorities from medical research continued until Congress mandated that they be included. As a result of this change in practice, researchers in gender based biology are starting to reexamine drugs that were tested only on men. They are checking for their potential effectiveness because women metabolize drugs differently than men. 

Women and heart disease-

Heart disease is another area where gender based biology has identified differences between men and women. In 1991 the National Institutes of Health (NIH) implemented a landmark observational study concluded in 2006 called the Women's Health Initiative (WIN). WIN provided a great deal of data on women's health. Noteworthy is the finding that women aged 65 and older were more likely to die from heart disease than men. Also, under age 50 a woman's heart attack is twice as likely to be fatal as a man's (5). Experts suggest there are several reasons for this, one of them being that the symptoms of heart attack that men experience aren't necessarily the same for a woman (3). They can be more subtle than the severe chest pain that is the hallmark symptom for men. As a matter of fact, 71% of women reported feeling flu like symptoms in the weeks prior to having a heart attack (5). You can find more information on the topic of heart attack symptoms on The Mayo Clinic website here. A simple, noninvasive way to test for heart disease is the exercise stress test and recent research has provided more insight into the uniqueness of a woman's heart and the use of this diagnostic test.

Women Take Heart Study-

The Women Take Heart Study, conducted by researchers at Northwestern University, focused on determining the normal response of a woman's heart to exercise stress testing. An exercise stress test or treadmill test is used to check a variety of heart functions including: "heart rate, breathing, blood pressure ECG, and how tired you become when exercising" (7). A stress test can also help diagnose or predict safe levels of exercise, coronary artery disease, possible causes of chest pain,  and risk for heart attack (7). During a stress test doctors monitor a patient to determine if they are unable to reach at least 85% of their maximum heart rate. Failure to reach this benchmark means a greater risk of death from heart disease. How a woman's heart rate (HR), or the number of times a heart beats per minute (BPM), responded to the stress of an exercise stress test wasn't understood very well until the Women Take Heart Study. This is because up until this point most of the research in this area had been conducted on men.

Maximum heart rate formula based on male data-

Scientists have known that maximal heart rate (MHR) decreases with aging (9). As a result, the formula that doctors typically use to calculate a normal response to exercise stress includes a person's age. However, the formula doesn't take into account gender differences. The simplest form of the maximal heart rate calculation based on data gathered from research using men is: Average maximal HR (MHR) = 220 - age in years (9).

New maximum heart rate formula for women-

Now to the Women Take Heart study's exciting findings! This year Northwestern University researchers published results of their study that found "the traditional male-based calculation [of  MHR = 220 - age] overestimates the maximum heart rate for age in women" (8) especially in women over age 35 (10). The new gender specific formula for MHR is:

MHR = 206 -  88 percent of your age

Aerobic physical activity and heart rate-

Women whose stress tests were measured using the old formula tended to show a poorer prognosis, so this gender specific formula reflects a more accurate prediction of a woman's risk for heart disease.  The new formula is also important because heart rate is the standard method for monitoring aerobic exercise intensity. Using this new formula for MHR while calculating an aerobic training heart rate will more accurately reflect how hard a woman is exercising during aerobic physical activity. For example, a 50 year old woman's MHR using the old formula would be: 220 - 50 = 170. If she were shooting to work at a moderate to vigorous intensity range her training heart rate (THR) using the old MHR formula and the simple THR formula would be: 111 (170 x 65%) at the range's lower end and 145 (170 x 85%) at the range's higher end (see the Heart Rate Training Zones Chart below).

From American Council on Exercise

Using the new Women Take Heart MHR formula a 50 year old woman's MHR would be: 206 - .88(50) = 162. So, now the lower end of her THR range would be: 105 (162 x 65%) and at the higher end of her THR: 138 (162 x 85%).

Most charts will reflect training heart rate zones calculated with the old "men only" formula so keep this in mind when you're at the gym monitoring your exercise intensity. Also, exercise equipment and heart rate monitors have usually calculated THR using the old formula. However, some companies are already updating their equipment, but ask to be sure. There's also talk of an I phone app that can do the calculations for us.

It's important to note that some medications, like beta blockers taken for blood pressure control for example, can give false pulse readings. In this case, it is more accurate to measure your level of aerobic exercise intensity using Rate of Perceived Exertion or the Talk Test. You can read more about the rate of perceived exertion here, and the talk test here. Next week's post will go into a little more detail about the aerobic training zones, discuss the myth of the fat burning zone and also look at how doctors are using heart rate response to exercise as a predictor of disease and even death.

There were some limitations to the Women Take Heart study. Nevertheless, the researchers at Northwestern state that their findings "should be incorporated into clinical practice" (12). This research also underscores the importance of conducting more studies that take into consideration the fact that women are biologically unique and not just mini-men. Thanks to gender based biology research, health care might begin to treat the sexes differently.  

Sources

(1) Gender Biology: Men and Women Really Are Different. Films Media Group, 1998. Films On Demand. Web. 20 November 2010. <http://digital.films.com/PortalPlaylists.aspx?aid=10103&xtid=11115>.

(2) http://www.nature.com/nm/journal/v2/n11/abs/nm1196-1248.html 

(3) http://www.mayoclinic.com/health/heart-disease/HB00040 

(4) http://www.washingtonlifescience.com/readlist/ceo_bianco.htm

(5) http://www.womensheart.org/content/HeartDisease/heart_disease_facts.asp, http://www.womensheart.org/content/HeartAttack/heart_attack_symptoms_risks.asp

(6) http://www.nhlbi.nih.gov/whi/  

(7) http://www.heart.org/HEARTORG/Conditions/HeartAttack/SymptomsDiagnosisofHeartAttack/Non-Invasive-Tests-and-Procedures_UCM_303930_Article.jsp
(8) http://www.medpagetoday.com/PrimaryCare/ExerciseFitness/20954

(9) American College of Sports Medicine, Resource Manual for Guidelines for Exercise Testing and Prescription, 2nd ed.

(10) http://seattletimes.nwsource.com/html/health/2012244688_heart05.html 

(11) http://www.cdc.gov/physicalactivity/everyone/measuring/index.html
(12) http://www.medpagetoday.com/PrimaryCare/ExerciseFitness/20954