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Why is my heart rate higher than my training partner while running?

In my capacity as the exercise physiologist at the IRONMAN Sports Medicine Institute at Memorial Hermann and as an associate professor at the University of Houston-Clear Lake, I have had many opportunities to speak to running, cycling and triathlon groups. A common question and point of concern at most of these workshops is training heart rate. The following are some insights into your heart rate response to exercise and why wearing that HR monitor may be limiting your training success.

At a recent talk to a running group, I was asked, “When I go running with my training partner, her heart rate is way lower than mine, even though we are going the same pace.” My response: Exercise is a stressor that will elicit a different response in each and every individual. It is perfectly normal for your training partner’s heart rate to be different than yours! 

Your overall heart rate response to work begins with your heart rate maximum, that is, the maximum number of beats per minute you can achieve. Your training partner may well have a much lower HRmax than you do. So, there is reason No. 1 for your training partner’s HR being lower than yours – her HRmax is lower. The next question is usually, “Well why is her HRmax lower than mine?” The answers there are multiple and too complex for this short article, so let’s just say that her heart does not need to, or cannot, produce as many beats per minute as yours. 

For those of you who use heart rate zones to train by, there are several formulas to predict your HRmax. The most common formula is HRmax = 220 – Age. This formula – like all the others – is simply an educated guesstimate and is only accurate for about 10 percent of the population. The only way to truly know your HRmax is to have a maximal test performed. So, I would advise you to do some type of maximal test to measure your true HRmax, especially if you are going to live and die by the almighty HR Zone. 

The most common reason your training partner’s HR may be lower than yours is fitness level. The more aerobically fit a person is, the lower their HR response to work. Thus, a person with a higher level of cardiovascular fitness will have a lower HR at specific paces. But this is not one of those “golden rules” of exercise training, as someone who is more fit may well have a higher HR response. How can this be? Well, a person’s heart rate is actually a function of many different physiological feedback mechanisms. Many different things, irrespective of fitness and exercise intensity, can influence a person’s heart rate. Things such as heat, humidity, specific drugs, diet, recovery state, fatigue, sickness and others can increase an athlete’s heart rate. This is why I’m not a particularly big fan of using heart rate to train by. I generally counsel my athletes to train by pace – for the run – and by perceived exertion when cycling or swimming. Your heart rate is just too easily influenced by “outside” factors and can well limit your actual training responses.