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Aerobics/Aerobic Intensity


Thank you for you answer concerning aerobic maintenance. I have a follow up question.
At the moment my main concern is  aerobic maintenance.The 3 days that I do cardio is usually 20+ Minutes in my THR zone of 99-125 BPM (65-82% MHR). I use a 6" aerobic step because in Georgia this time of year it is to hot to walk outside. In addtion to the 20+ minutes in THR zone  I also warm up and cool down < 65% MHR. Of that 20+ minutes I would estimate 15-17 Minutes are greater than 70% MHR (107 BPM) Will this maintain my aerobic fitness? Should I add an extra low impact workout (60-70% MHR)
Last question. CDC states >70% MHR is vigorous , ACSM states now 77% MHR  is vigorous. Is 70% MHR Vigorous ? You have been a big help.
Thank You Again,
Tom Boyd
Grovetown Ga 30813

Thanks for your question.  It can by confusing when organizations aren't always in sync or agreement as to definitions and terminology. The CDC is oriented more to the average person and what will be appropriate for better health outcomes.  ACSM is oriented more to the active or athletic person who although may also be interested in better health, may also be interested in better athletic or sport performance.  That may explain why the organizations define vigorous differently.

Again, Tom, it may be splitting hairs.  Whether it's 70% or 77% of MHR isn't going to be an all or nothing difference in terms of maintaining your cardio fitness.  If you're somewhere around that intensity, you're likely maintaining your cardio fitness.  And 3x weekly should be adequate frequency. Notice the terms used... "likely"..."should"... because it cannot be stated that it's a 100% guarantee you'll maintain cardio fitness at 77% of MHR done 3x per week.  Maybe for you, it will be 2x a week to keep you there, or maybe you'll have to do it 4x weekly to keep you there, or maybe you can be in your training zone (TZ) for 15 minutes and maintain your fitness, or you may need 22 minutes to maintain your fitness, or maybe you can be at 65% and maintain your fitness, or perhaps you need to be at 80% to maintain your fitness, or maybe intervals between 60% to 80% is optimal for you to maintain your cardio level.  There are a number of variables, and a number of training protocols that are effective.  Just understand that until you test yourself by doing a protocol for a few months will you know what the results are for you.  There really is no one specific program/protocol that can be recommended because everyone reacts slightly differently to the exact same program.  My suggestion is to not be so concerned by whether you need to be at 70% or 77% of MHR, or go for 15 minutes or 20 minutes in your TZ.  As long as your close to those figures, that's good enough to maintain your aerobic fitness.  There are many opportunities in obtaining an inaccurate training HR as well, no matter what devise is being used, so that needs to be taken into account as well.  Technology is good, but not quite perfect yet.  Unless you're a competitor in a cardio activity, I'd make sure to enjoy the activity being done rather than make sure I'm working at a precise intensity for a precise period of time.  It's almost feeling if you don't accomplish that objective, you've received no benefits at all and all that effort was wasted.  That's hardly the case.  Just keep doing what you're doing.  No need to split hairs.  You're on the right track.  Unfortunately, without assessing you, it's not possible to tell you the exact track that is based upon your physiology.

If you truly want that info, get together with a qualified trainer of other professional that can give you a VO2 Max test.  That way, you can get the numbers that you seem to be seeking.
Hope this helps.


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Ken Alan


To build a strong body, build a strong body of knowledge. Exercise workouts, training programs, classes, program design, workout music, motivation. Cardio, strength, flexibility.

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