The Fat Burning Zone - Fact or Fiction?

I'm 33 and my morning resting heart rate is 48bpm.  Before the winter, my typical workout was a 100 minute bike ride three times a week.  70 minutes were in the 60-70% range, 10 minutes in the 70-80% range, 5 minutes in the 80-90% range, and the rest below 60%. Now that it's winter, I've been attending a spin class at my local 24 Hour Fitness four times a week (well, five this week).  That's 60 minutes, 50 minutes in the 70-80% range, the rest in warm-up and cool-down.

Hi Jeremy, I am 53 years old.  I have been a 176 pounds for the last two years.  I have a resting heart rate of 52.  My exercise regime currently consists of 3 spin classes followed by body pump sessions three times per week.   My rate is between 70-80% intensity depending on the instructor.  I usually strive to keep the heart rate at 145-155 during spinning classes.  On the other two days I run 3.5 miles at ~10 minutes/mile.  Heart rate is more in the 125-140 rate.  I follow up each run with yoga or pilates class.  I am dabbling with swimming laps in the pool.  Although I would prefer working out in the morning, my schedule only permits to start working out at 6pm.  When I council people I tell them to try and work out in the morning so they don't come up with an excuse to not exercise.  I find out least in the evening I am able to use exercise to calm and de-stress myself.  I am also an advocate for all RNY patients to follow-up with a cardiologist since most of us have abused our bodies for many years and losing weight does not always repair the heart,. On the weekend I participate in either a long run (longest 10 mile) or a 35-50 mile bike ride.  I'm currently training for either a triathalon (sprint) or dualothon (depending on my success in the pool) in 2007. I have recruited a group of four people in the Delaware, PA, NJ area to participate with Team Gastric.  We currently ride the MS 150mile Bike to the Bay as the only gastric bypass cycling team in the nation.  DE Rob

I'm 45 and exercise 4-5 times a week at the YMCA.  I do 30 minutes on a recumbant bike.  My heart rate is kept between 125 and 160.  I've gotten up to 8 minutes on the eliptical machines.  I have a hip injury so I have to take it easy on my hip. My doc says it's an injury that hockey and soccer players get, when in reality, I got it when I fell wearing high heals on a slippery floor.    No walking, I have  a tear in the cartliage that requires surgical repair although I would like to get around it if I can....I don't know if I can though.    I do strength training on the abductor both inner and outer 10 @40lbs x 4, rotary calf machine 10@50lbs x 4, chest press 10@30lbsx4, pectoral machine 10@30lbsx4, arm extension 10@30lbsx4, upper back 10@40lbsx4, vertical traction 10@60lbsx4, low row 10@50lbsx4, arm curls 10@30lbsx4, and the leg press 10@40lbs, 10@50lbs, 10@60lbs. 10@40lbs. I also have some stretching exercises from my physical therapist to help my hip.  I do hamstring stretches, hip rotator stretches, knee to chest, quadricept stretch, prone press-up, partial curl up, the bridge. About once a week I will go down to the pool and swim some laps, I have a goal to beat my husband across the pool.  I enjoy swimming and the y has a wonderful lap pool.  I have done as many as six laps so far.   So I have a lot of exercise going on and actually love it.  I never thought I would say that but I do.   I get an overall great feeling when I exercise which keeps me going back for more.  I have now lost 170 pounds and am feeling much better.  I exercise at 5am because by the end of the day, I don't want to. If I get up and go and do this, I have a better day than if I wait.  Also it pumps me up enough to help me keep the stamina for my day, if I exercise at night, I don't get to sleep in time to get enough rest.

Jeremy, I just read another article you wrote, "Cardiorespiratory Training Before and After Weight Loss Surgery", which indicates that you should have a gradual progression in heart rate.  How important is that?   I'd love some help figuring out what I should be doing.  I'm 47 years old, and my morning resting heart rate is 58 bpm.  I've been working out on the elliptical machine for 30-45", 6 days a week, from 130-150bpm.  My biggest challenge so far is that my feet start to go numb in places after about 30".  I also do strength training on the Cybex machines 2-3 times a week (alternating upper & lower body machines).  According to the "Fat Burning Zone" article, I should be working at 144-150 bpm.  But, according to the other article, at week 7 (since beginning the exercise habit), I should only be working out for 30" at 127-139.   Also, do I still do my full cardio workout on the days that I do strength training?  Before or after?  Can I split it up, and do 15-20" of cardio before and 15-20" after strength training?   I had a Resting Metabolic Rate test done at the health club, and it showed my RMR to be 1930.  Does that have any application in deciding an exercise routine or intensity? Thanks for all your advice! Tami

There is one key difference in terms of what method I used to explain exercise intensity or target heart. Most people are familiar with simply using a percentage of max heart rate; this is what I used for the fat burning article. The method I used for determining target heart for the cardiovascular training article was heart rate reserve. Calculating heart rate reserve takes a little more explanation so I did not have room to use it in the fat burning article. Consider max heart rate and heart rate reserve as two different scales. So, 75% of max hear rate will not be the same as 75% of your heart rate reserve. Rather, 75% of your heart rate reserve will equal around 85% of your estimated heart rate max. It would be similar to once physician asking you to rate pain on a 1-10 scale and another physician asking you to rate pain on a 1-5 scale. Both achieve the same thing.....generally speaking. The cardiovascular training article was essentially intended for people new to exercise and basically gives exercise recommendations based upon safety and not energy source utilized during exercise. Please let me know if you need more explanation here. Also, check out the link below so you can compare the percentages of each method for calculating target heart rate. You can check out the two different calculators at the link below: http://www.obesityhelp.com/forums/fitness/cmsID,2290/mode,content/ You can certainly do your full cardio workout on the same days you do your strength training and yes you can also split it up into 15-20 minutes prior and post resistance training. In terms of resting metabolic rate, this is used to determine how many calories you need to consume per day to maintain body weight if you were completely sedentary. To get a true number of total calories used in one day, you would have to factor in calories expended during your working day and your exercise. Once you calculated or estimated how many calories total you needed for one day, you could then plan your diet from there. Let me know if this helps.

The heart rate reserve is a more accurate way of determining your appropriate level of exercise, though, right?  The figures I get using that method are higher, and the same as the figures I get on the PolarUSA site that uses the morning resting heart rate and age to determine target heart rates.  Based on that info, my plan is to warm up for 5" at 60-65% of HRR (127-133 bpm); then continue for an additional 30-40" at 75-80% of HRR (144-150 bpm), and then cool down for 5" at the lower range.  Does that sound appropriate?   Tami

Yes, HRR is a more accurate way to do this and the info you have provided certainly sounds appropriate. I would also encourage you to experiment with interval training. For instance, you could exercise for two minutes at a low intensity and then 30-60 seconds at a pace that is all out. This works great, is very challenging and will keep things interesting for you.

Thanks, Jeremy!  I really appreciate your help and advice! Tami