April 16, 2013
Even Fit People At Higher Death Risk With High Heart Rates
Brett Smith for redOrbit.com — Your Universe Online
According to a new study published in the journal Heart, a higher resting heart rate could be a greater risk indicator than a person´s overall fitness.
While physically fit individuals tend to have lower at-rest heart rates, researchers at the University of Copenhagen wanted to see if heart rate itself had any indication of an individual's risk of death, regardless of their fitness capacity.
"A high heart rate does not necessarily mean disease," study author Dr. Magnus Thorsten Jensen, a cardiologist at Copenhagen University Hospital Gentofte, explained to HealthDay. "But we know that there is a very strong and significant association between high heart rate and life expectancy."
The doctor added, “resting heart rate is not just a marker of fitness level, but an independent risk factor.”
To reach their findings, the Danish researchers used data from the Copenhagen Male Study, which followed almost 3000 men for 16 years.
Initiated in 1971 to observe the cardiovascular health of middle-aged men at large companies in Copenhagen, the study began with interviews about the participants´ health and lifestyle, including smoking and exercise. They were also given a standard physical exam, which included an assessment of their physical fitness using a stationary bicycle.
The participants were given a follow-up exam between 1985 and 1986, which included measurements of their weight, blood pressure, blood glucose and resting heart rate.
A follow-up of the study in 2001 revealed 39 percent, or 1082, of the men had died. The study´s statistics showed the higher the resting heart rate, the greater risk of death, regardless of fitness level.
After compensating for compounding factors, the team discovered an at-rest heart rate of between 51 and 80 beats per minute was linked with a 40 to 50 percent increased risk of death. Those with a resting heart rate between 81 and 90 beats per minute were found to have twice the risk of death compared with those with the lowest resting rates and resting heart rates above 90 beats per minute tripled that risk.
The authors concluded every 10 to 22 added beats per minute in resting heart rate raised the risk of death by 16 percent on the whole. When smoking was taken into account, every 12 to 27 added beats per minute increased a smoker´s risk by 20 percent, while non-smokers saw a 14 percent increase in risk for every added four to 24 beats per minute.
The authors assert their study effectively discriminates between a higher resting heart rate and its implication of a lower level of physical fitness.
"We found that irrespective of level of physical fitness, subjects with high resting heart rates fare worse than subjects with lower heart rates,” they wrote in their report. “This suggests that a high resting heart rate is not a mere marker of poor physical fitness, but is an independent risk factor."
According to Jensen, the study´s results mean the so-called normal range of heart rates at rest — between 60 and 100 beats per minute -- should be reevaluated, since the higher end of range appears to be a sign of increased risk.