Just three weeks of exercise and a healthy diet produced positive changes in middle-aged men with a cluster of heart risk factors known as metabolic syndrome, according to a new study from Austria.
Among two groups of men sent on a hiking vacation, one at sea level and the other at just over 5,500 feet altitude, benefits were about the same and no negatives were seen, suggesting that exercising in the thinner air at altitude is neither better nor riskier for health, the researchers say.
"The data of the AMAS-2000 study proved that daily hiking for hours at any altitude provides cardiovascular benefits and represents an excellent therapeutic opportunity for physical and mental regeneration even for individuals with a cluster of cardiovascular risk factors," Dr. Guenther Neumayr said in an email.
Metabolic syndrome is a cluster of characteristics, including abdominal obesity, high cholesterol and triglycerides, high blood sugar and elevated blood pressure. People with metabolic syndrome are at greater risk for cardiovascular disease and diabetes.
Neumayr, a medical doctor practicing in Lienz, Austria, was part of the team that designed the Austrian Moderate Altitude Study 2000 (AMAS-2000) to determine if hiking at a moderately high altitude might be any different from hiking at low altitude.
Between 5,000 and 8,000 feet above sea level is considered moderate altitude. Cities within that range include Albuquerque, New Mexico
; Denver, Colorado; Nairobi, Kenya; Lima, Peru
and Mexico City.
The air pressure at that altitude is similar to what it feels like to be on a commercial airplane. And the oxygen concentration in the air is approximately 17 percent, compared to 21 percent at sea level.
To test whether exercise at moderate altitude posed any additional risks or offered extra benefits, the researchers recruited 71 men, ranging in age from 36 to 66 years old, and randomly assigned them to three-week vacations at one of two Austrian resorts located in Obertauem, at 5,577 feet above sea level, or in Bad Tatzmannsdorf, at 650 feet above sea level.
The men all had metabolic syndrome and were non-smokers, the researchers note in their report, published in the journal Wilderness and Environmental Medicine.
Health professionals led the men on moderate intensity hikes that lasted more than two hours each. They hiked four days a week and rested the other three. The men in both groups also had similar diets, averaging about 1,800 calories per day.
The researchers weighed the men, measured their abdominal and hip circumferences and took blood samples several times during the study.
At the end of three weeks, men in both groups had lost an average of 7 pounds and showed similar drops in blood pressure readings, heart rate, blood sugar and similar improvements in cholesterol.
In both groups, for example, resting heart rate fell by just under three beats per minute from measurements taken two weeks before the vacation to measurements six to eight weeks afterward. In the group that exercised at altitude, blood pressure dropped from an average 187/94 to 179/90, compared to the sea level group whose average readings went from 191/96 to 184/87.
"It is the daily activity, not the altitude which provides the benefits in the health effects," Neumayr said.
Past research had suggested that hiking or skiing at a moderate elevation can increase the risk of cardiac arrest, however, those studies also found that cardiac events tended to happen on the first day at a higher altitude and that people who had already had a heart attack were the ones most at risk, Neumayr and his colleagues write.
All the participants in the new study tolerated the vacations well and no adverse events were seen at either altitude, they add.
"Walking and hiking are activities of low to moderate exercise intensity which can be performed by nearly everyone - even by patients with metabolic syndrome featuring obesity and poor cardio-respiratory fitness," Neumayr said.
The difference in air pressure between the two altitudes is marginal, he pointed out.
"Therefore, there is no significant effect on the individual's performance between these two altitudes - everyone featuring bad fitness has, of course, to exercise for some time at sea or low level to be able to start effective training," he said.
Neumayr said that years with insufficient physical activity have led to higher rates of obesity and metabolic syndrome.
"Thus, walking and hiking - the original forms of motion - should be recommended generally and generously for both healthy people and patients with metabolic syndrome," he said.
People with health conditions such as chronic obstructive pulmonary disease or who have been diagnosed with heart disease may have difficulty breathing at higher altitude and should talk to their doctor before traveling to cities located at moderate or higher elevations.