“Pregnancy is the longest duration, highest energy expenditure thing that humans can do. Mothers probably aren’t surprised by this.” Herman Pontzer
How fast you can run depends on why, for how long and more importantly the drive that sets the purpose for why you are running in the first place. As in all emergency situations, trying to avoid being a tiger’s lunch does not take long: You either run as hard as ever to demonstrate clearly to the charging tiger that it’s not worth the effort to burn its limited energy for an uncatchable running “human bullet” that you are, or it would be over within minutes with an eternal loss of the right to brag about how you outrun a tiger.
Needless to say, physical activity is metabolically expensive and that explains why humans are inherently lazy but we would go out of our way to let people know we “walk or exercise all the time” but actually “don’t eat much”. To that end, it is easy to remember the details of the last time we took a long walk in the neighborhood or the intense sweating time in the gym. However, unlike exercise that costs energy, hardly does anyone remembers the meals they had in the last 24 hours because consumption comes with energy gain. That said, energy is not limitless and there is therefore a hard limit to human endurance before exhaustion sets in and the brain shut down intense activity as the mental fatigue struggles with the deep inaudible but increasingly loud inner voice stating, “I am too exhausted” to run another mile and “I do not want to do this, it is not worth it”. This is why athletes need coaches.
A 2019 study reported that the metabolic ceiling for all humans is 4,000 kilocalories per day which is roughly 2.5 times the basal metabolic rate where metabolic rate (1,000 to 2,000 kilocalories for most people) can roughly be described as the energy to keep alive at rest. The study noted that prolonged activity above this metabolic ceiling would require burning energy reserves and therefore not sustainable indefinitely as the gut’s digestive competence is maxed out.
The Ironman triathlon event only lasts less than a day but involves swimming (2.4 mile), bicycling (112 mile) and running (26.2 mile). Also less than a day, the record time for Western States 100-mile Endurance Run is currently 15 hours 7 minutes, 4 seconds. According to the bicycling, the total mileage for Tour de France is about 2,200 miles over the 21 days of racing, and in 2015, Scott Jurek hiked the 2,189-mile Appalachian Trail in 46 days, eight hours, and seven minutes. Finally, the longest ever man-made endurance event is the 3,000 mile Race Across the USA where runners, from Southern California to Washington, DC, did one marathon (26.2 mile) a day, six days a week for 140 days. To say the least, these are insanely unsustainable activities and it’s no wonder they don’t last several months.
However, here comes the pregnant mama who sets out on a solo 9-month endurance trip with no pre-coaching and still outlasts all known voluntary man-made athletic endeavors in the history of life. She thrives on 2.2 times basal metabolic rate, near the edge of the human metabolic ceiling for 270 days! As declared by Herman Pontzer, the author of Burn, “pregnancy is the ultimate ultramarathon”. Just as you don’t forget the details of your recent energy-expensive workout or perhaps how you gallantly outrun a tiger, mama remembers your pregnancy history too, if you ask her or it might come up unprompted if you have time like I did during my recent visit to Nigeria. I learnt of the loss of my mom’s first pregnancy, the years it took to conceive me and some events that occurred during my stay in the womb.
Beyond that, as I went out for a walk in the street every day, it did not matter whether it was for 40 or 120 mins, like someone still protecting her almost 60-year-old energy-expensive womb investment, mama would step out of the house and sat outside anxiously by the gate watching the street for me to show up.
To my mama, the mama of my children and all mamas out there, happy Mother’s Day.
Mukaila Kareem, a doctor of physiotherapy and physical activity advocate, writes from the USA
