A Voice of Experience with Heart Rate Monitors

Kim Kazimour -- Marathoner, Iron Woman Triathlete -- Gainesville, FL

Max Heart Rates Vary

When you train, you need to use your HRM based on a maximum number for you in that particular activity...each person is different and so is each activity.  Maximum heart rate (MHR) differs for different activities due to the different workload of each.  A biking MHR is lower than running because cycling is not a weight bearing activity, thus your heart does not need to work as hard to propel you forward.  Swimming maximum heart rates are typically lower still, as swimming is also not weight bearing AND the cooling effect of the water decreases the workload created by your body's need to regulate temperature.  A large part of the energy expenditure for any activity is created by the body's need to cool itself. 

Affects on the HRM Readings

Heart rates are also greatly effected by air temperature with heart rates in the heat of summer for the same perceived level of effort in any sport being roughly 10% higher than they would be in the winter.  Dehydration also significantly increases heart rate at the same perceived level of effort, as in a dehydrated state (regardless of air temperature) your body is having to work harder to get rid of excess heat.  The effect of these two factors is compounded when you become dehydrated AND it is very warm outside.  This is why a summer run when you are low on fluids feel SO incredibly hard even when your pace is slowing.  This is also why you see people wishing for cool days with low humidity for marathons....such weather minimizes the amount of energy your body is using to cool itself and thus leaves more of your workload available to run a faster pace.

Easy/Hard Days with the HRM

HRMs are probably most useful in making sure that your easy days are actually run at an easy pace.  Most people train at a HR level which is too high on their easy days and move between medium high and high HR's in their workouts, never really running an easy day.

What typically happens is that when you begin to use a HRM for training on easy days, you have to run MUCH slower..even walk...to get your HR down to where it is supposed to be.  But, over time, you begin to be able to go slightly faster and maintain this HR...in the end, this translates to a faster pace at higher effort levels.  Many folks find this difficult to do, but some of the top triathletes have found it to be effective, although even they had to run very slow/walk to get their HR's down on the easy days, in the beginning. 

HRM training takes a lot of patience and so may not be a good fit for everyone, however many top folks feel that it has helped them a great deal. Most of us have no problem running at an effort level which gets our heart rates up high...it's the other end that is a problem...making easy days easy.  When you do this, you also decrease your risk of injury as you are actually allowing your body to rest on easy days, which is the whole point.

Many people have found that combining some truly easy days with weekly interval training (speedwork) into their workout plan can give them unexpectedly good results in comparison to running pretty much every run at 80% or above (which is what many of us end up doing)....