Let’s say you’re 5’8”, 150lbs, and you run a 10-minute mile. Over the course of a 3-mile run, your knees will experience a compressive load of nearly 3 million pounds.
Wait….what? Let’s calculate this.
For every pound of body weight, a knee experiences about 4 pounds of pressure when a foot hits the ground.[i] So, if you weigh 150 pounds, your knee experiences 600 pounds of pressure per stride. In addition, a person who is 5’8” and runs a 10-minute mile takes about 1,600 strides per mile.[ii] Do you see where we’re going with this?—
(150lbs weight x 4lbs pressure/lb) x (3mi x 1,600 strides/mi)= 2,880,000lbs in compressive load!
In truth, exactly how many pounds of pressure your knees bear during walking and running is uncertain. Some experts say that for every pound you weight, your knee experiences only 2 pounds of pressure per stride, while others estimate nearly 7 pounds of pressure.[iii] But what’s not up for debate is that your knees (and hips, and ankles) take a pounding.
That doesn’t mean running is bad for you! A good running program can actually help build muscles, support healthy bones, and strengthen joints. It might also boost your brain’s memory and executive function abilities.[iv, v]. Admittedly, not all scientists agree on that last point, but it’s what some of us tell ourselves as we lace up our running shoes.
Another bonus: a 3-mile run burns approximately 340 calories[vi], which is about the number of calories in a slice of apple pie!
So if you are ready to give your knees a challenge in exchange for some calorie-burning and added brain function, come join us for our Pi Day Run!
[i] Messier SP, Gutekunst DJ, Davis C, DeVita P. Weight loss reduces knee-joint loads in overweight and obese older adults with knee osteoarthritis. Arthritis Rheum. 2005 Jul;52(7):2026-32. PubMed PMID: 15986358.
[ii] Hoeger W, Bond L, Ransdell L, Shimon JM, Merugu S. One-mile step count at walking and running speeds. ACSM’s Health and Fitness Journal, 12(1):14-19, January/February 2008. http://www.yamaxx.com/digi/m-magazine/ACSM_Health%26FitnessJournal.pdf Accessed February 28, 2017.
[iii] Bergmann G, Bender A, Graichen F, et al. Standardized Loads Acting in Knee Implants. Williams BO, ed. PLoS ONE. 2014;9(1):e86035. doi:10.1371/journal.pone.0086035.
[iv] Chapman SB, Aslan S, Spence JS, Defina LF, Keebler MW, Didehbani N, Lu H. Shorter term aerobic exercise improves brain, cognition, and cardiovascular fitness in aging. Front Aging Neurosci. 2013 Nov 12;5:75. doi: 10.3389/fnagi.2013.00075. PubMed PMID: 24282403; PubMed Central PMCID: PMC3825180.
[v] Guiney H, Machado L. Benefits of regular aerobic exercise for executive functioning in healthy populations. Psychon Bull Rev. 2013 Feb;20(1):73-86. doi: 10.3758/s13423-012-0345-4. Review. PubMed PMID: 23229442.
[vi] Calories Burned Calculator. http://www.runnersworld.com/tools/calories-burned-calculator
Jennifer Flynn is a freelance science writer. You can follow her on Twitter @FlyWrite1.