By Brady J. Holmer, @B_Holmer
Humans have successfully conquered herculean feats of endurance in some of the most unbearable conditions on Earth. Such conquests as the Badwater Ultramarathon, 135 miles (217 km) through Death Valley, where temperatures can reach 130˚ F (54˚ C), or the 100k Antarctic Ice Marathon (average wind-chill -4˚F (-20˚ C)) not only require a certain amount of mental fortitude (some might call it insanity), but also careful consideration of human physiology and its inherent limits. Unpreparedness for such harsh climates can spell disaster; Mother Nature isn’t merciful to those who are ill-prepared. In tests of extreme endurance, environmental conditions, and the body’s response to those conditions, can be the dividing line between successful completion of the race and a certain meltdown.
It is unlikely that humans will ever lose their aspiration to push the limits of human physiology through feats of endurance. Given humanity’s recent interest in colonizing planets other than our own, it seems likely that our sporting and recreation habits will make their way out into the cosmos.
Indeed, Tesla CEO and Mars colonization proponent Elon Musk thinks that exploring new planets isn’t just a choice we have, but a necessity, and projects that the first manned trip to Mars will leave no later than the year 2020 (1). Should we colonize Mars, humans will have stay active to prevent muscular atrophy, deconditioning, and boredom. Eventually, someone will have the crazy idea to try a marathon on the newly colonized Red Planet.
However sci-fi this situation may seem, it is interesting to ask what physiological and technical challenges a Martian marathon would provide. Will the vast climactic differences between Mars’ atmosphere and our own prove insurmountable? Will the elite road runners of our modern time be reduced to hobby joggers in the extreme climate? Or, perhaps even more tantalizing, will this novel atmosphere allow us to finally run a marathon under two hours? Let’s explore the physiology of humankind’s first marathon on Mars.
It may be important to note that the first Mars marathon has been completed, although not by a human. On Tuesday, March 24, 2015, Mars exploration Rover “Opportunity” completed the 26.219-mile (42.195k) journey across the Red Planet’s surface (2). Opportunity’s performance was quite mediocre, finishing in approximately 11 years and 2 months (a speedy pace of 222,000 minutes per mile). Let’s hope humans can improve on the current record.
Fortunately, thanks to Opportunity, we have a perfectly measured course, and the Red Planet marathon will follow the same route, putting the finish tape at the rim of Endeavor crater. On this journey, how will environmental conditions be different, and what adjustments will be required to nutrition and protective clothing? Stay tuned to find out.
The Martian environment
Will the environment on Mars be conducive enough to run, much less perform well in, a marathon, even for the most battle-hardened endurance veterans? Various factors about the climate, both positive and negative, affect physical capacity and physiological response.
Pros: A giant leap for mankind
One benefit, taking nothing else into account, is that runners will be lighter on Mars. Martian gravity is a little less than one third that of the Earth, so a man or woman weighing 154 pounds (70 kilograms) on Earth will weigh a mere 51 pounds (23 kilograms) on Mars. Many of the top-100 world class marathon runners typically weight around 123 pounds (56 kg) – so if we forget about the danger of “floating away” for a moment– this puts Martian runners way below the “elite” weight class.
Weight reduction will dramatically increase V02max (maximum oxygen use, which measures exercise capacity) relative to body weight without any training required! The transition to partial gravity will cause an immediate 67% increase in relative V02max. Compared to changes seen in an Experimental Physiology study in which V02max increased only around 9% after 6 weeks of aerobic exercise training (3), this is quite the shortcut.
Another beneficial change upon arrival to Mars will have to do with the biomechanics of running. Even if we design aerodynamic spacesuits which provide ample range of motion and reduce mass as much as possible, human locomotion will differ substantially; our running will look more like skipping, in fact. Apollo astronauts discovered the benefits of skipping on the Moon. A bouncing gait in the low-gravity conditions on Mars will also be preferred to walking and running since it leads to a threefold reduction in cost of movement. In addition to reducing work, skipping enhances grip control, which will be helpful on Mars’ surface. Covered by in “lunar dust”, it provides little in the way of friction.
Stride rate, typically 150-160 steps per minute for a marathon runner, will dramatically fall on Mars. This is mainly due to the large vertical displacement and increased time spent in the “flight” phase while skipping. Airborne time while running will be 80% longer in duration than on Earth, and stride length approximately 3 times as long. On Earth, the average stride length is 54 and 74 inches (1.3 to 1.8 meters) for men and women, respectively. This means that Martian marathoners will travel around 13.5 to 18.5 FEET (4 to 5.5 meters) per stride. Compare that to Usain Bolt, who has a stride length of about 7 feet (2 m). Talk about a “giant leap for mankind.”
The above changes, resulting in only a decrease in work and slight increase in biomechanical efficiency, may be the only beneficial alterations in running physiology on Mars – and it might look quite funny. Indeed, where gravity gives runners a benefit, the other environmental factors on Mars will all work against running a fast marathon.
Check back next week to learn how the freezing temperatures, and lack of oxygen impact the marathoners, as well as how they’ll fuel up and what they will wear.
- Elon Musk Has a New Timeline for Humans Living on Mars. June Javelosa. February 19, 2017. https://futurism.com/elon-musk-has-a-new-timeline-for-humans-living-on-mars/
- NASA’s Opportunity Mars Rover Finishes Marathon, Clocks in at Just Over 11 years. NASA release 15-049. March 24, 2015. https://www.nasa.gov/press/2015/march/nasas-opportunity-mars-rover-finishes-marathon-clocks-in-at-just-over-11-year
- Montero et al. Haematological rather than skeletal muscle adaptations contribute to the increase in peak oxygen uptake induced by moderate endurance training. The Journal of Physiology. 593.20 (2015); 4677-4688