Cardio Vs. Fat Burn Vs. Peak

[kewl1]

I'm 70 years old, male, 5'10"  and used to weigh as much as 223 at the most.  I got colon cancer 2.5 years ago and started walking to get in a little shape for the operation. I got to 212 I ended up at 184 after the first operation, chemo etc. Then another operation knocked more weight off and I have gotten as low as 160 and that is now my target.   Due to having some guts removed, I can't eat huge meals so I try to eat smaller.  I'm walking about 2 miles each night.  It is easy for me to gain back pounds and I'm usually a few over my target like 162-164.  It was the Oncologist who told me to walk half an hour per day, 5 times per week and he said for "cardio".  Oncologist, cardio?  I don't get that but I walk every night unless it's raining.

Usually, I have no or little peak and more of either cardio or fat burn or both.  I heard a doctor say we should "power walk".  Well, that really shot up the peak and reduced the others.  But now my brother,  a sometimes marathon runner told me that he thinks Peak means your burning muscle instead of fat.  I have no muscle to burn.  My arms are skinny and I have no chest, not to mention a bum shoulder that hurts like hell if I try to exercise.

So correct me if I am wrong but I would think that any of this walking should be good for cardio.  I want to keep weight off so fat burn has a nice ring to it.  Should I really avoid Peak?  I would have thought that would give me everything.

Years ago I went to a meeting and saw a guy I hadn't seen for 3 months.  He had lost 30 pounds so I asked him how.  He said that he had purchased a heart monitor and was walking.  He claimed that if he kept to a certain speed, not too fast and not slow the weight would peel off him which it did.

So This is probably a dumb question, but should I be trying to adjust my walking speed to maximise the bar that says "fat burn"? And avoid Peak?

[SunsetRunner · Accepted solution]

From looking at the help on my fitbit, It estimates your heart rate with a formula 220 minus your age, then calculate your 3 zones based on that. Fat Burn zone is low to medium intensity exercise (Walking), Cardio zone is medium to high intensity between 70%-84% of your maximum heart rate (fast walking/ cycling), peak zone is high intensity exercise (high impact running).

the body burns sugars first, then fat. It only burns muscle if you don't increase your intake to match your outgoing.

I'm not a professional, so for more advise i would reccommend visit a doctor or a nutritionist.

[kewl1]

Thanks so much, Joanne.   This is extremely helpful.  I just did the calculations and what you say regarding burning muscle seems to make so much sense.

Tom

[Dominique]

If your main preoccupation is losing weight, you should focus your attention on energy balance (calories in vs. calories out), as opposed to (over)thinking how much time you spend exercising in the various HR zones.

It’s possible to spend a couple of hours everyday exercising in the "fat burning" zone and not lose any fat at all (if you end up consuming more calories at the daily level than you are burning). OTOH, it’s also possible to lose weight without exercising at all, i.e. without spending any time in the "fat burning" or higher zones (as long as you consume few enough calories to be in a deficit).

As to exercising in the "peak" zone burning muscle: yes, high intensity cardio activities tend to be "catabolic" (= they break up muscle tissue), whereas resistance training (e.g. weight lifting) is "anabolic" (= builds muscle tissue).This may be an issue for true "meat heads", but probably isn’t for ordinary dudes like you and me. The improvement in cardio fitness that results from exercising in the peak zone will likely outweigh any minor loss of muscle tissue you may experience. If maintaining muscle mass is of concern, resistance training should be included in your routine.

[kewl1]

Thanks very much, Dominique.  I can't believe I am trying to learn how to exercise at 70.  45 years ago I studied karate for almost 4 years and then never exercised at all after that.  Now that I feel like I am getting closer to the end of my life at what seems like an alarming speed, I want to do all I can to stretch it out. Your answer is very helpful.

Tom

[FrankD0417]

I realize this is 3 years old now so hope you are still around to answer this ( or someone one maybe can? 🙂

I'm confused by your answer ( and that's only due to my ignorance on the subject I'm sure 🙂  .

You stated that PEAK mode breaks down the muscle tissue? and that lifting weights builds muscle? 

I've always been told we Lift Weights to exhaustion because that is what it takes to Break down the muscles so that they can REBUILD bigger / stronger..   isn't peak doing that to your muscles? breaking them down? and then it has to rebuild them with the protein?  or did I miss something in the process of muscle building?

[t.parker]

@FrankD0417 it's a lot more complex. It's not Peak causing muscle breakdown. First of all, I don't agree with Fitbit zones naming (it's misleading and has no connection with any possible training effect, just made up). The zone that is associated with muscle breakdown is usually known as "anaerobic" (and there's one even higher - "neuromuscular"). You are right, muscles breakdown is caused by... well... breaking down the muscles, damaging them due to intense exercise. However, to do that you need to fuel your body in order to generate the energy. For an anaerobic activity like weight-lifting the main source of fuel is glycogen which is broken down without using oxygen (hence the name "anaerobic" - "without oxygen"). There is an association between a higher heart rate (above lactate threshold) and switching to using glycogen as a source to power your muscles. Anaerobic glycogenolysis (breaking down glycogen stored in your muscles) is used to power muscle contractions during maximal exertion. That maximal exertion is what damages your muscles so they can recover as stronger/bigger. So it's not the "Peak" zone that breaks down your muscles. "Peak" may be used as an indicator of going from aerobic effort into the anaerobic effort. Still, this isn't so simple. The anaerobic training effect is associated with mixed periods of rest and intense exercise (rest helps replenish ATP so you can go back for the next set or prepare to take another steep hill on the bike). Staying in "Peak" for a longer period (assuming that Peak represents anaerobic and above-threshold zones) will cause your muscles to produce lactic acid and eventually, fatigue will kick in (it's an all-out effort, in weight-lifting you'd probably have to execute set until failure). The effect of such effort is different from the cardiovascular standpoint (and has nothing to do with breaking down muscles, that happens due to mechanical damage regardless).

[charleskn]

I think the cardio your doctor is referring to is cardio-vascular exercise, to get your heart beating faster than normal. This shouldn't be conflated with what your Fitbit calls the cardio zone.

In general working in the fat zone allows for longer, less intense exercise and tends to burn fat first. Cardio/peak zone exercise will burn carbohydrates first.

One thing to think about is something called EPOC. Studies show that while a longer less intense workout may burn as many calories as a shorter and more intense workout. However, the more intense workout will most likely induce EPOC, which means your metabolism is still cranking for longer, after the workout, which burns additional calories in the long run.

[t.parker]

@charleskn effect of EPOC is marginal and appears also after less intense steady state cardio. EPOC is a great buzzword. Especially, overused by "coaches" offering magic 10min HIIT workouts and promising burning vast amount of calories due to EPOC  (of course, one need to buy a plan or supplements etc.). It carries minimal impact on energy expenditure. EPOC involves small percentage of calories burnt during workout. Short, even intense workout won't burn a lot and a few percent of that is worth a banana at best. I wouldn't even consider EPOC as relevant at all.

[FrankD0417]

I"m not doing to disagree with any of what you said.. it can be 100% true..

I can just tell you from MY experience.. and research, that my results.. matched .. 

I lost about 30lbs.. and started to want to push it more. as I was a walker .. I started jogging/running for 1 week, then back to walking, then a week of jogging and walking. .did this for about a month and a half, before I noticed on Fitbit.(. my Scale measures muscle weight / mass etc.). and the graph went down over the next 1.5 months.. 

Which told me what I had read, about pushing my muscles.. will burn muscle so to speak, as opposed to walking and just burning fat.. ( Again I realize there is a ton more to all this .. but in simplistic mode ).. this is what seems to be happening to Me? I take in Protein all day to build muscle .. 

I start going down in muscle.. ( Albeit, very minor amounts .1 -.3 ) .. I Never did that  when walking.. just UP . up up .. ( very sedentary before walking. so building leg muscles. etc. ) 

So, I stopped the jogging/running week, because it was easier than jogging for 1 month straight to see what happened LOL .. and went back to walking. and it started going up again, about a week later.. I've been just walking for the past 2 months. and it didn't go up and down like it did when I was jogging/running ..  just almost a steady level up .. little bit but always in an up.. as opposed to the 1.5 months of up and down.. 

Granted there were probably half a dozen things I was doing wrong that caused it.. Maybe it required more protein PRE and POST drinks on jogging/running days? ..   

were all different. and not everyone will gain/lose etc. by eating and doing what the guy next to him/her does..   IMO

[charleskn]

What are you doing to build muscle? Running is a lower body exercise, and you can build some muscle there, depending on your current state. Consuming protein and running (is not bad) but you won't gain any substantial muscle without strength training. The results will also depend on your age.