Rather than escape the blistering heat of summer, there may be good reason to embrace it. For the first time, research has shown that heat acclimation can lead to performance gains similar to that achieved through hypoxic (low-oxygen) training.
The benefits of training at altitude have long been heralded by endurance athletes. Essentially a natural form of doping, the rise in erythropoietin (EPO) is swift in most individuals – helping to boost red blood cells and oxygen-carrying capacity of the blood within 24-48hrs of arriving at altitude.
In the real world, most athletes aren’t fortunate enough to live at or near altitude and don’t want to drop the money to snooze in an altitude tent. Luckily, sweltering summer heat is readily accessible.
UK researchers asked male cyclists to complete a self-paced hypoxic time trial before and after a series of 10 daily 60-minute training sessions in either hot (40oC), hypoxic, or control conditions. In the hypoxic condition, the percent oxygen approximated a target altitude of about 10,000ft.
Findings, published in Frontiers in Physiology, showed that hypoxic time trial performance and power output were comparably improved for the cyclists who trained in both the low-oxygen and hot environments. Those who trained in the control conditions saw no gains. Similarly, blood results indicated that the 10-day training protocol in both the hot and hypoxic conditions improved cellular tolerance to exercise. Heat shock protein (Hsp) 72 was of particular interest, as it has been linked to delayed tissue injury and cellular resilience to environmental stressors (such as… hypoxia).
Moreover, the authors note, “Heat acclimation induced a greater adaptive stimulus at lower levels of metabolic strain, and in a shorter time frame compared to hypoxic acclimation.” These conclusions were based on the finding that the heat-trained group showed a more efficient aerobic profile, with increased hemoglobin saturation, a higher oxygen pulse (more O2 uptake per heartbeat at rest), and a significantly lower exercise heart rate following acclimation. There was also a smaller increase in body temperature during exercise for the heat-trained cyclists.
The implications here are potentially huge for athletes, suggesting that heat-based training could offer a more proficient means of improving altitude tolerance than equivalent training at actual altitude. An important caveat here is that hypoxic conditions were normobaric. Because pressure wasn’t altered, it’s not yet known whether these findings would hold at natural (i.e., hypobaric) high-altitude environments.
In addition, these researchers went quite hot with their heat-trained group, subjecting them to 40oC (104oF) conditions. Hopefully, the minimum temperatures necessary to reap these physiological benefits are not quite so stifling!
So, if you’re preparing for a high-altitude trek, ultramarathon, adventure race, or any other aerobic event up high, you might want to simply tap into the cardiovascular and cellular benefits provided by the ever-accessible summer heat. You may be a hot sweaty mess, but you’ll be an endurance phenom!