Machu Picchu. Credit: Anne Crecelius

After spending three weeks getting to know the geography of Chile and making important connections with other academics, I treated myself to some tourist activity in Peru, Chile’s neighbor to the north. I met my mother in Lima, and we began a nine-day tour to visit the famous Incan sites of the Andes.

One major concern for travelers who visit mountainous regions is adjusting to a higher altitude. Upon our arrival in Cusco (11,200 feet above sea level), we quickly departed for a bit lower elevation in Ollantaytambo (9,160 feet) to allow our bodies to adjust to the high altitude. This type of itinerary is common for visitors to help minimize the chance of acute mountain sickness.

As we began to explore the Incan ruins of the Sacred Valley, it quickly became obvious that the altitude challenged most of the tourists (we were no exception!), but the many native tour guides seemed unaffected. Many native highlanders were also working as porters, not only hiking the famous Inca Trail, but carrying heavy loads with ease while doing so. I wondered how they made it look so easy.

Highland natives have long been studied in an attempt to understand how they have adapted to altitude over time and how their genes affect their adaptation. However, given the semi-remote locations where many of these populations live (the Andes, the Himalayas, etc.) and the small number of people participating in research studies, questions still remain.

A recent review article tried to answer the “nature vs. nurture” question as to why high-altitude natives are able to perform so well at high altitude. On the nature side, genes may regulate the ability for highlanders to maintain higher levels of oxygen in their blood. On the nurture side, it appears there are important changes in the lungs of high-altitude natives at very early ages that increase their efficiency in gas exchange in the lungs as adults. Gas exchange is one of the important factors in aerobic capacity (VO₂) and the ability to perform work or exercise. Essentially, the natives develop greater breathing efficiency at high altitude, even when compared to lowlanders that have acclimatized or adjusted over a number of days.

Between catching my breath and thinking about the physiological challenges my body faced, I was able to enjoy the Peruvian landscapes and the rich Incan history. The highland natives of Peru are not only physiologically impressive but gracious hosts as well!

This post concludes a three-part series by physiologist Anne Crecelius, PhD, chronicling her summer of research and travels through South America. (Read part one and part two.) Crecelius is assistant professor at the University of Dayton.