A couple new papers and stories in the media have me thinking more about running lately. I don’t make a big habit out of it, but I do occasionally do some hill sprints and 5k races just for fun, and to mix up my exercise routine. Sometimes I think there is a bit too much naysaying of running and moderate-intensity endurance exercise in general within the Paleo community, and in light of this new research, I wanted to reexamine running within a Paleo framework.
Jogging has gotten a rather cold reception within the Paleo community, but I’m not sure that’s entirely fair. First of all, it’s a really easy activity to do. You don’t need a home gym or thousand dollar bike to do it. A decent pair of shoes (I prefer minimilist shoes) and a bit of sidewalk or trail will do. Second, by stepping up the intensity occasionally, it’s an easy way to reach those peaks of exertion required for the cascade of positive metabolic effects to occur if one is pursuing a weight-loss/metabolic conditioning program. Brief bursts of high-intensity training can increase insulin sensitivity, leptin sensitivity, reduce blood pressure, and increase one’s resting metabolism, among other benefits.[1,2]
There is also no doubt that some amount of running was routinely practiced by the Paleolithic people whose’s genetic heritage we carry. It’s very difficult to imagine living in the wild without occasionally running after prey, running from predators, running from/after competing groups, etc. And let’s not forget about persistence hunting.[3,4]
Now, don’t get me wrong. It’s very easy to overdo it. Running marathons, for example, has been shown to cause subclinical heart damage.[5-7] Running for long periods can also expose the runner to an excess of the stress hormone cortisol and oxidative damage. We just need to know what’s healthy and what probably isn’t.
Jogging, or running at a moderate pace for an extended period, is really what get’s the ire of a lot of people, and mostly for good reasons. This is probably exactly what most people picture when reading Mark Sission’s famous “Chronic Cardio” post. But what about joggers that don’t aspire to run marathons and just go out for a few miles every couple of days?
A new, unpublished study found a U-shaped correlation between jogging time and life expectancy.
Undertaking regular jogging increases the life expectancy of men by 6.2 years and women by 5.6 years, reveals the latest data from the Copenhagen City Heart study presented at the EuroPRevent2012 meeting. Reviewing the evidence of whether jogging is healthy or hazardous, Peter Schnohr told delegates that the study’s most recent analysis (unpublished) shows that between one and two-and-a-half hours of jogging per week at a “slow or average” pace delivers optimum benefits for longevity.
Further analysis exploring the amounts of exercise undertaken by joggers in the study has revealed a U-shaped curve for the relationship between the time spent exercising and mortality. The investigators found that between one hour and two and a half hours a week, undertaken over two to three sessions, delivered the optimum benefits, especially when performed at a slow or average pace. “The relationship appears much like alcohol intakes. Mortality is lower in people reporting moderate jogging, than in non-joggers or those undertaking extreme levels of exercise,” said Schnohr.
Two and half hours of jogging per week is a lot more jogging than a lot of Paleo enthusiast are comfortable with (15 miles at a nice-and-easy 10 minutes/mile), but it appears to be safe.
Now, of course, this type of study cannot show causal relationships–there could be other factors at work. For instance, joggers are less likely to smoke, drink excessively, and probably try to eat a healthier diet than most non-joggers. All of these things affect the difference in life expectancy between joggers and non-joggers, but that doesn’t explain why jogging more than 2.5 hours a week ends up having a negative effect, as one would assume joggers that go out even longer are even more committed to leading a healthy lifestyle.
Another study looked at the neurological effects of running (aka the “runner’s high”). They found that a runner’s body produces cannabinoids, the same type of chemicals found in marijuana.* The researchers wondered if this was an evolutionary adaption for species that enage in distance running, and loe and behold, found the same effect in dogs (distance runners) but not in ferrets (not distance runners). While too much running is clearly damaging, there is still evidence that we were “Born to Run” as it’s been put.
So there you have it. Jogging is a perfectly healthy part of a Paleo lifestyle. Just skip the sugared-up exercise drinks, run as close to barefoot as possible, run on uneven terrain to reduce repetitive stresses on the joints, and keep your overall time low. If you want to be out all day, go for a long hike or low-intensity bike ride instead.
* Tangent: The press has presented this as if running is as addictive as hard drugs, which makes about as much sense as claiming marijuana is as addictive as hard drugs. Why everything that activates the reward centers of the brain is considered addictive, I will never understand. Pleasurable experiences, including the use of hard drugs, do active the brain’s reward centers (big surprise), but clearly there is more to the story than blobs on an fMRI. Some rewards we can manage, some we can’t. Just looking at fMRI’s and ignoring the behavioral aspects of addiction because we now have “hard evidence” is foolish.
1. Babraj JA, Vollaard NB, Keast C, Guppy FM, Cottrell G, Timmons JA. Extremely short duration high intensity interval training substantially improves insulin action in young healthy males. BMC Endocr Disord. 2009 Jan 28;9:3. PubMed PMID: 19175906; PubMed Central PMCID: PMC2640399.
2. Irving BA, Davis CK, Brock DW, Weltman JY, Swift D, Barrett EJ, Gaesser GA, Weltman A. Effect of exercise training intensity on abdominal visceral fat and body composition. Med Sci Sports Exerc. 2008 Nov;40(11):1863-72. PubMed PMID: 18845966; PubMed Central PMCID: PMC2730190.
3. Bramble DM, Lieberman DE. Endurance running and the evolution of Homo. Nature. 2004 Nov 18;432(7015):345-52. PubMed PMID: 15549097.
4. Liebenberg L. The relevance of persistence hunting to human evolution. J Hum Evol. 2008 Dec;55(6):1156-9. Epub 2008 Aug 29. PubMed PMID: 18760825.
5. Möhlenkamp S, Lehmann N, Breuckmann F, Bröcker-Preuss M, Nassenstein K, Halle M, Budde T, Mann K, Barkhausen J, Heusch G, Jöckel KH, Erbel R; Marathon Study Investigators; Heinz Nixdorf Recall Study Investigators. Running: the risk of coronary events : Prevalence and prognostic relevance of coronary atherosclerosis in marathon runners. Eur Heart J. 2008 Aug;29(15):1903-10. Epub 2008 Apr 21. PubMed PMID: 18426850.
6. Wilson M, O’Hanlon R, Prasad S, Deighan A, Macmillan P, Oxborough D, Godfrey R, Smith G, Maceira A, Sharma S, George K, Whyte G. Diverse patterns of myocardial fibrosis in lifelong, veteran endurance athletes. J Appl Physiol. 2011 Jun;110(6):1622-6. Epub 2011 Feb 17. PubMed PMID: 21330616; PubMed Central PMCID: PMC3119133.
7. Neilan TG, Januzzi JL, Lee-Lewandrowski E, Ton-Nu TT, Yoerger DM, Jassal DS, Lewandrowski KB, Siegel AJ, Marshall JE, Douglas PS, Lawlor D, Picard MH, Wood MJ. Myocardial injury and ventricular dysfunction related to training levels among nonelite participants in the Boston marathon. Circulation. 2006 Nov 28;114(22):2325-33. Epub 2006 Nov 13. PubMed PMID: 17101848.
8. Witt EH, Reznick AZ, Viguie CA, Starke-Reed P, Packer L. Exercise, oxidative damage and effects of antioxidant manipulation. J Nutr. 1992 Mar;122(3 Suppl):766-73. Review. PubMed PMID: 1514950.
9. “Assessing prognosis: a glimpse of the future.” Symposium: Saturday May 5, 9.15 am to 10.15 am. Liffey B Lecture Room. P. Schnohr, Jogging-healthy or hazard?
10. Raichlen DA, Foster AD, Gerdeman GL, Seillier A, Giuffrida A. Wired to run: exercise-induced endocannabinoid signaling in humans and cursorial mammals with implications for the ‘runner’s high’. J Exp Biol. 2012 Apr 15;215(Pt 8):1331-6. PubMed PMID: 22442371.