Clearing up muddy waters: low and high intensity activity

ultramarathonI would like to start out by saying I am sorry if I brought about confusion regarding lower intensity exercise and I thought I should be a little more descriptive about it.  I feel very bad that I might have confused people into thinking that low intensity is the only way to lose fat.  It is not, but it is the only way to improve endurance.  High intensity will not improve your endurance if that is what you are after.  Sorry.  Here is a post that explains the the plain truth regarding low and high intensity workouts.
Throughout my journey of weight loss I have had one very very focused goal.  The number one goal was not to just lose weight.  MY GOAL FROM THE START WAS TO FIND SOMETHING THAT WAS SUSTAINABLE FOR THE REST OF MY LIFE SO THAT I COULD LIVE A HEALTHY AND FIT LIFESTYLE WEEK AFTER WEEK, DAY AFTER DAY.  Keep this in mind please as you read this post.
Here is what prompted this post:
…… My first trainer told me to stay in the target to burn fat, … and he was having me do 60-90 minutes of target heart rate cardio 4 times a week. But my current trainer says she wants me doing a mile 4 times a week, as fast as I can push it, and we’ll build up the distance later. It irritates me getting this conflicting information, but I do seem to be burning more fat now than I was before….”

Ok.  The higher the intensity, the more calories burned.  This is true and there is no getting around it.   It is also true that the higher intensity limits the amount of time spent doing the activity.  It is self limiting because of what is called, “lactate threshold”.  Once you hit this point, you cannot keep going.  Sprinters use a pace so that they have used up all energy in 100 meters.  Marathons use a pace where they use up all energy in 26.2 miles.  Although the sprinter is burning calories faster and more powerfully, the marathoner has burned exponentially more calories.  Here is a chart from about.com regarding high and low intensity activity and their respective calorie burning potential.

  Low Intensity – 60-65% MHR High Intensity – 80-85% MHR
Total Calories expended per min. 4.86 6.86
Fat Calories expended per min. 2.43 2.7
Total Calories expended in 30 min. 146 206
Total Fat calories expended in 30 min. 73 82
Percentage of fat calories burned 50% 39.85%


So looking at this chart  you burn 206 using 30 minutes of high intensity activity.  It would take you 42 minutes to burn that many calories using 30 minutes low intensity activity.  Which one is better?  Both are a means to the end of losing weight.  They both work.  Why do I like the low intensity activity better?  I can live with that and do it more often with decreased chance of overuse running injuries.  Lets take running for example:  High intensity running day after day increases the risk for injury a lot so you should only do it like 2 days a week.  If I run for 30 minutes 2 times a week at high intensity I burn 412 calories.  If I run at a low intensity 5 times a week for 30 minutes I burn 730 calories.  If I run 2 days a week hard (hard/easy rule) and three days a week easy for 30 minutes each time, I burn 850 calories.  I also like it better because it is better at getting me to my goal of attaining endurance and not just fat loss.  If you just want fat loss and are not interested in gaining endurance, higher intensity will suffice better for you.
Bottom line:  It is simple fact that the higher the intensity the more calories are burned.  If you want to burn the most calories possible right now then this is maybe better for you.  You have the potential to lose more fat.  The other simple fact is that low intensity activity allows for the build up of endurance (which is what I am always after) while teaching your muscles to use fat as the primary energy source.  This is important for endurance running because sugar is limited and you have to be able to keep going once the sugar is mostly gone. 
Here is an article from a guy name Tom Venuto.  He is a non-biased trainer and really tells it like it is.  His main thing is that your results are what dictates how you do your cardio. I lost 40lbs using his principles but could not sustain the program for long term and ended up gaining like 80 lbs after I stopped.  I am sorry if I caused confusion with my posts.

13 Responses to “Clearing up muddy waters: low and high intensity activity”

  1. January 13, 2009 at 9:15 am

    If all you are doing is 30 mins then odds are that high intensity is going to work better (if you don’t get injured). However, you can go longer with low intensity (with much less risk of injury) so you probably end up burning more overall. For most of us I think it’s just a plus to be doing something! 🙂

    PS Thanks for the link you sent me. You’re the second person to recommend them so I’ll definitely try and track them down here in NZ.

    • 2 run4change
      January 13, 2009 at 9:37 am

      Thanks for your contribution. It is a great comment for this post and it helps clear things up even more. And you are 100% right that just doing something is the #1 thing, hands down it is the most important thing

  2. January 13, 2009 at 9:31 am

    Great post. I am currently using the H.I.T. method and am seeing great results.

  3. 5 thefamilymannie
    January 13, 2009 at 10:09 am

    Thanks for your support! Your blog looks like a great resource, so i’ll be sure to keep dropping by!
    -Annie S.

  4. January 13, 2009 at 11:32 am

    Yup, I’m glad the boy told me I could work out at less intensity to lose fat. If it wasn’t comfortable, I wouldn’t stick with it. And being consistent is the key to success as you well know!
    I’m a weenie when it comes to discomfort so working out longer at low intensity works for me.
    Thank God, is all I can say.
    I agree though that we all have to find what works for us.

  5. 9 Angela
    January 13, 2009 at 12:15 pm

    Hmmm I left a comment here earlier, but don’t see it now. Perhaps I’m dillusional….anyway, wanted to say thanks for doing an official post on this. I’m unofficially in the 270’s, a weight I haven’t seen for 6 years! I say unofficially because my trainer weighed me in today, but my WW weigh in is Thursday. Your guidance is truly helping me to burn it off!

    • 10 run4change
      January 13, 2009 at 12:25 pm

      For some reason the post would not go up onto the blog fully. Only half of it would so I ended up having to delete and re-write the whole thing. I would not let me cut and paste it either. If I did that it would still only show half. So I did it all over again. Your comment was deleted when I had to delete the post. I am sorry about that. Luckily you had the whole post by email though. Thanks for your encouragement.

  6. 11 myweightylossjourney
    January 14, 2009 at 1:57 am

    Thanks for this post. I don’t generally do high intensity training. It hurts too much. I’d much rather train longer at a lower intensity, but still push myself. I’ve always heard that lower intensity is a waste of time.

    • 12 run4change
      January 14, 2009 at 5:53 am

      When you are trying to lose weight and move towards health, no exercise is a waste of time. Some ways take the weight off faster, but I think in general a longterm perspective will bring more health. My sister showed me last night the Oprah show with Eric, the biggest loser #3, he had gained so much weight back. I mean, he is a normal person, but image if it had taken him three years he would have just been getting to his goal right now and would not have gained anything.

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