Expert: Brandon Briggs, MS - 10/30/2008

Question
QUESTION: What does it feel like if you get too close to your maximum heart rate?  I had a sensation when on the tread mill that I could not get enough air (could not take a deep enough breath) and got rather panicky about it.  I was able to calm down enough to eventually catch up oxygen wise.  This happened when running, when stopping running and walking up a very steep incline (30%).  I even had the sensation while hooked up to a stress test for cardio (cardiologist did not tell me what had happened, she did say am I ok to go a little longer before the sensation happened, that is why I suspect got close to max heart rate) It no longer happens, but I went to western doctors and no one could figure out what happened.  My resting heart rate is between 50 and 60 and my BP has been around 110/70 and am 47 years old.  The heart rate devices on the equipment I use show my rate never exceeds 144 BPM, but I am unable to use them while running.  I have manually checked using a 6 second count and got rates of 150-165+ I am 6'8" and 330 pounds.  I have been trying to go below 330 (seem to be stuck there).  Docs have recommended more cardio, hence the reason I am asking.  I have not had the problem happen for some time now and am looking to find out if it is some kind of condition that happened that I can look for and avoid (like getting heart rate too high, etc).  When I run, it is with a weighted backpack that weighs between 20-50 pounds.  It is designed to fit well without restricting my chest or stomach from taking in air, and not bouncing around a lot.

ANSWER: Mr. Kern,

Since I am not a physician I don't want to speculate as to any condition that may have caused this sensation. In my years of employment working with both fit and un-fit individuals ranging from all ages and sizes I have not had any describe this type of feeling. I have had some patients during their max stress test say that they experienced extreme shortness of breath. However, if your cardiologist did not explain your stress test to you, I would start there. I would ask for an explanation of the test in detail. Were there any EKG changes at the upper ranges of your HR, also what was the max HR from the test. It almost sounds like you reached your threshold. This can happen if your heart muscle is not getting the proper amount of oxygen to fuel it. In the cases where I have seen this the patient experienced angina, which can be pain in their chest, arm, jaw, etc, or only described as shortness of breath. During reading your post I do have one concern. If your goal is weight loss running with a 20-50 pound pack may not be beneficial. True weight loss is described as a neg balance of calorie intake to output. Simply put you have to burn more than you eat. The pack does help increase HR, but adds a heavy amount of impact on your joints. With your size I don't recommend adding excessive joint impact. Other conditions could have had an effect as well. Things such as the environment you were running in. Was it cold out, were you in a controlled environment? At first thought I would have thought you had exercise educed asthma however your physician did not diagnose you with that so I am a little stumped.
Sorry I could not have been more assistance to you.

In Good Health,

Brandon


---------- FOLLOW-UP ----------

QUESTION: I am lowering my calorie intake and use the extra weight in the back pack to burn more calories.  The cardiologist did explain that she saw the EKG as perfectly normal, and that it was apparent that I was not in shape for the running up hill part (but running on the flat I was great at). I am only jogging between 4.5 mph to 5.5 mph, not full on running.  I slowly worked my way up to running to minimize joint impact.  I did have an earlier physician diagnose me with exercised induced asthma, and I was taking medication for it, but my current physician has retested me several years ago and is saying I don't have any symptoms at all.  I am a little hesitant as any asthma medication raises heart rate, and if it is not asthma but too high of a heart rate, I will make it worse (and or fatal).  I have been taking MSM and an Ayurveda respiratory cleaning herbal formula.  I also have been seeing an acupuncturist, he along with my physician say I have no symptoms of an asthma problem (the acupuncturist stated it was a blood sugar drop that is causing the breathing problems.  He also stated I probably sweat like crazy, which he was right) Both of those together have drastically reduced any shortness of breath, so if anything the placebo affect has saved the day.

Answer
The extra weight in the pack really doesn't contribute to your caloric burn. The equation for caloric expenditure while walking or running does not take into account weight. If anything it creates more of an anaerobic response and not a fat burning response. If you get your heart rate to high you can switch from aerobic to anaerobic, meaning you are not using fat for fuel anymore. I did have one other thought about what could cause the shortness of breath. This is only a theory.. if you switched from an aerobic to anaerobic pathway the fuel broken down could have caused an excess in Carbon dioxide limiting the oxygen in your blood stream. This could have caused an increase in shortness of breath. My advise....keep your heart rate in the range of 125 - 148 bpm. That is based off the age predicted max using the equation 207 - (.7 x age).

If you have more questions please let me know. I would also be interested in your progress.

Brandon