Achieving Hunter-gatherer Fitness in the 21st Century: Back to the Future PDF

REVIEW Achieving Hunter-gatherer Fitness in the 21st Century: Back to the Future James H. O’Keefe, MD,a Robert Vogel, MD,b Carl J. Lavie, MD,c Loren Cordain, PhDd a Mid America Heart Institute/University of Missouri-Kansas City, Kansas City; bUniversity of Maryland, College Park; cOchsner Clinic,...

REVIEW Achieving Hunter-gatherer Fitness in the 21st Century: Back to the Future James H. O’Keefe, MD,a Robert Vogel, MD,b Carl J. Lavie, MD,c Loren Cordain, PhDd a Mid America Heart Institute/University of Missouri-Kansas City, Kansas City; bUniversity of Maryland, College Park; cOchsner Clinic, Jefferson, La; dColorado State University, Fort Collins. ABSTRACT The systematic displacement from a very physically active lifestyle in our natural outdoor environment to a sedentary, indoor lifestyle is at the root of many of the ubiquitous chronic diseases that are endemic in our culture. The intuitive solution is to simulate the indigenous human activity pattern to the extent that this is possible and practically achievable. Suggestions for exercise mode, duration, intensity, and fre- quency are outlined with a focus on realigning our daily physical activities with the archetype that is encoded within our genome. © 2010 Elsevier Inc. All rights reserved. The American Journal of Medicine (2010) 123, 1082-1086 KEYWORDS: Cardiovascular health; Cross-training; Evolution; Exercise; Fitness; Hunter-gatherer; Obesity; Prevention Physical activity is decreasing in our society, especially in sents the exercise patterns for which we remain genetically children as they mature.1 Clear evidence suggests that phys- adapted. Accordingly, humans are superbly capable of per- ical activity has numerous favorable beneficial physiologic forming the wide array of physical actions and behaviors effects that result in demonstrable reductions in cardiovas- required of the hunter-gatherer. Quantum improvements in cular and other disease endpoints. Daily exercise substan- technology such as those that spawned the agricultural revo- tially alters the expression of a substantial proportion of the lution (350 generations ago), the industrial revolution (7 gen- genes that comprise the human genome.2,3 These profound erations ago), and the digital age (2 generations ago) have and far-reaching changes in genetic expression may explain engendered large systematic reductions in the amount of phys- why cardiovascular fitness and daily energy expenditure on ical work required by humans.10,11 Nonetheless, our innate physical activity are among the strongest correlates of long- exercise capabilities and requirements that evolved via nat- term health and survival2-7 (Figures 1, 2). ural selection over thousands of millennia remain essen- From the inception of the human genus, Homo, approxi- tially the same as for our Stone Age ancestors. Marked mately 2.4 million years ago,8 our ancestors lived as hunter- deviation from those indigenous exercise patterns predict- gatherers for approximately 84,000 generations.9 Survival ably results in physical disability and disease. An under- within the hunter-gatherer niche required a large amount of standing of the typical hunter-gatherer physical activity pat- daily energy expenditure in activities such as food and water tern would seem to be an ideal template from which to procurement, social interaction, escape from predators, and design a modern exercise program. maintenance of shelter and clothing. This lifestyle repre- FITNESS FOR LIFE IN THE WILD Funding: There was no funding or compensation made in the writing Ironically, today, as the last vestiges of the hunter-gatherer of this article. lifestyle are being eclipsed by modern civilization, science Conflict of Interest: None. is coming to realize the importance of this way of life for Authorship: All authors had access to the information and had a role current-day human health, and its relevance to optimal fit- in the writing of this manuscript. ness in the 21st century.12,13 Compared with the glacial pace Requests for reprints should be addressed to James O’Keefe, MD, Cardiovascular Consultants, Mid America Heart Institute, 4330 Wornall of genetic evolution, human technological and social evo- Rd., Ste. 2000, Kansas City, MO 64111. lution has occurred at light speed. This discordance has left E-mail address: [email protected] us genetically adapted for the rigors of life as a hunter- 0002-9343/$ -see front matter © 2010 Elsevier Inc. All rights reserved. doi:10.1016/j.amjmed.2010.04.026 O’Keefe et al Achieving Hunter-gatherer Fitness 1083 gatherer despite the fact that we are citizens of the high- benefits conferred by a hunter-gatherer style of fitness reg- tech, sedentary, overfed, emotionally stressed 21st-century imen. A growing body of data indicates that many of the world. The intuitively obvious solution to this conundrum is benefits of exercise accrue at relatively low to moderate to simulate the activity patterns of our Pleistocene ancestors. levels of exercise.17 Continuous higher-level activity, such Natural selection endowed us with the genetic makeup as jogging 32 km/week, was not found to be statistically that allowed our ancestors to not better than walking 19 km/week only survive the physical work for reducing features of the meta- and daily rigors required of the bolic syndrome.18 On the other CLINICAL SIGNIFICANCE hunter-gatherer but, to thrive in hand, a daily regimen of at least response to these demands.14 Our Humans remain genetically adapted for 45 minutes and possibly up to 90 ancient ancestors evolved an in- a very physically active hunter-gatherer minutes per day of cumulative stinct compelling them to “Move lifestyle. Many of the health problems physical activity is necessary for when you have to, and rest when most overweight or obese individ- endemic today result from lifestyle that you can.” Many of their waking uals to achieve and maintain ideal hours were necessarily consumed is at odds with this evolutionary milieu. body weight.19 The 10,000 steps with the physical activities re- The daily physical activity pattern of per day concept emphasizes the quired of everyday life (Table the hunter-gatherer is an ideal template importance of total daily en- 1).15 Except for the very young or from which to design a modern exercise ergy expenditure. This fitness the very old, everyone did a wide regimen. strategy generally involves walk- range of manual labors on a daily ing at a modest pace intermittently basis. Their activities of daily life Characteristics include: incorporation of throughout the day.20 Combined were all the “exercise” that Stone physical activity into daily life wherever aerobic and resistive activity has Age people would have ever needed possible, interval and strength/flexibil- been shown to be superior to ei- to maintain superb general fit- ity training, outdoor exercise on natural ther alone for improving glycemic ness.16 Instincts to preserve en- surfaces, group exercise, ample time for control for individuals with type 2 ergy and strength for these requi- rest/recovery, and lifelong fitness. diabetes.21 Intermittent intense ac- site physical chores conferred tivity results in more weight loss survival advantages to hunter- and better glucose metabolism gatherers. However, this inborn than equivalent amounts of lower- proclivity to take the path of least resistance plays a major intensity continuous activity.22 role in the health woes beleaguering modern Americans. Even though exercise in general confers powerful car- diovascular protection,23 some evidence suggests that phys- ical activity performed outside may be more beneficial than IDEAL EXERCISE PATTERNS indoor exercise.24 Outdoor exercise offers the opportunity The prospective clinical trials that have been performed for sunlight exposure, which stimulates vitamin D synthesis assessing the health effects of various exercise regimens and the observational data are generally supportive of the health 100 Low physical activity %) ortality (% M di Medium physical h i l activity ti it 80 High physical activity mulative total mo 60 30 20 Cum 0 50 60 70 80 90 Age (years) Age 50 60 70 77 82 End of Study Men at 2205 1904 1406 1123 933 876 risk Figure 1 Long-term mortality as a function of fitness is closely associated with fitness as assessed by peak exercise Figure 2 Reduction in long-term mortality in proportion to level achieved on a maximal treadmill exercise test.6 Repro- the amount of daily physical activity performed.7 Reproduced duced with permission. with permission. 1084 The American Journal of Medicine, Vol 123, No 12, December 2010 Table 1 Energy Expended: Hunter-Gatherer vs Moderns15 Species Sex Weight kg RMR kcal TEE kcal Ratio (TEE/RMR) EE PA kcal Day Range km Fossil hominids Homo habilis 48.0 1404 2387 1.70 983 Homo erectus 53.0 1517 2731 1.80 1214 Homo sapiens (early) 57.0 1605 2880 1.80 1284 Modern hunter-gatherers Kung M 46.0 1275 2178 1.71 903 10 F 41.0 1170 1770 1.51 600 8 Ache M 59.6 1549 3327 2.15 1778 16 Acculturated modern humans Homo sapiens M 70.0 1694 2000 1.18 306 2.4 (office worker)* F 55.0 1448 1679 1.16 231 2.4 Homo sapiens (runner)† M 70.0 1694 2888 1.70 1194 11 EEPA ⫽ energy expenditure attributed to physical activity; RMR ⫽ resting metabolic rate; TEE ⫽ total energy expenditure. *Sedentary office worker (4). †Runner running 12.1 km/h (4). in the epidermis. Vitamin D deficiency is a common and cross-training such as strength and flexibility exercises into potent risk factor for many health problems, including car- their prescribed training routines.32-34 diovascular disease.25 Outdoor exercise reduces emotional stress and enhances compliance to a daily fitness regimen better than indoor exercise.26,27 THE DANGERS OF EXCESSIVE EXERCISE AND Although hunter-gatherer women rarely participated in INADEQUATE REST large-game animal hunting,28 they too were very physically Whereas physical exercise is unquestionably protective, fit as a result of the demands of their daily physical routines. there are evolving data from Vogel et al35 and others that Ethnographic accounts of hunter-gatherers indicate that extreme physical activity may be detrimental to cardiovas- women typically went out foraging to collect food every cular health. Prolonged and excessive aerobic exercise ef- other or every third day. Women, usually in groups, spent forts such as marathons, ultra-marathons, full-distance tria- hours walking to and from sources of food, water, and thlons, and very-long-distance bicycle rides are inconsistent wood.4 Additionally, these forager women were often car- with our genetic heritage. The pattern of exercise for which rying their children for extended distances as well. Anthro- we are genetically adapted involves a diversity of activities pologists have estimated that the typical hunter-gatherer performed intermittently, at moderate intensities and mod- mother carried her child until about age 4 years, covering erate durations. Even in highly trained individuals, high- upwards of 4,800 km with the child in her arms over this intensity, multi-hour endurance exercise effort is associated period of time.29 with damage to the myocardial cells and connective tissue.36-39 REST AND CROSS-TRAINING Hunter-gatherers would have likely alternated difficult days NATURALLY REESTABLISHING with less demanding days when possible.16 Their routines CALORIC BALANCE called for endeavors that promoted aerobic endurance, flex- For all humans before the dawn of the Agricultural Revo- ibility, and strength; thereby bestowing them with multi- lution, energy input (food) and energy expenditure (physical faceted fitness that would have also conferred resiliency and activity) were directly and inextricably linked. When hu- reduced the likelihood of injury. The same pattern of alter- mans of the Pleistocene Age were hungry, they had to hunt, nating a strenuous workout one day with an easy one the gather, forage, and fish.4 Hunger, or even the threat of next day produces higher levels of fitness with lower rates inadequate food, instills a powerful motivation to move of injury.30 In exercise physiology, it has been well docu- with intensity and purpose. The convenient modern world mented that aerobic capacity within an individual may in- has virtually eliminated the evolutionary connection be- crease based upon exercise frequency, intensity, and dura- tween energy expenditure and calorie ingestion. The tion.31 Of these 3 factors, intensity is the most important “search and pursuit” time are minimized, while the caloric feature in optimizing the aerobic capacity, especially in an payoff is almost unlimited. Today, the acquisition of mas- already trained individual.31 The natural cross-training that sive amounts of calorie-dense foods and beverages requires was a mandatory aspect of life as a hunter-gatherer has been minimal energy expenditure. found to improve performance across many athletic disci- This systematic and pervasive disconnect between en- plines. Now, most endurance sport coaches incorporate ergy intake and energy expenditure inherent in modern O’Keefe et al Achieving Hunter-gatherer Fitness 1085 Table 2 Caloric Cost of Various Hunter-gatherer or Forager Activities and Recommended Equivalent Modern Activities4 Caloric Expenditure (Kilocalories/Hour) Hunter-Gatherer Activity Modern Equivalent Activity 176-lb Man 132-lb Woman Carrying logs Carrying groceries, luggage 893 670 Running (cross country) Running (cross country) 782 587 Carrying meat (20 kg) back to camp Wearing backpack while walking 706 529 Carrying young child Carrying young child 672 504 Hunting, stalking animals Interval training 619 464 Digging (tubers in field) Gardening 605 454 Dancing (ceremonial) Dancing (aerobic) 494 371 Carrying, stacking rock Lifting weights 422 317 Butchering large animal Splitting wood with axe 408 306 Walking – normal pace (fields and hills) Walking – normal pace (outside 394 295 on trails, grass, etc.) Gathering plant foods Weeding garden 346 259 Shelter construction Carpentry, general 250 187 Tool construction Vigorous housework 216 162 cultures is a fundamental factor in the obesity epidemic. These need to be performed at least 2 or 3 times per Increasing reliance on pharmaceutical agents to counteract week, for at least 20 to 30 minutes per session. this problem is much less logical than simply realigning our 6. Virtually all of the exercise was done outdoors in the lifestyle to be more physically active, (Table 2) and our diet natural world. to include more unprocessed, naturally low-calorie, whole 7. Much of the physical activity was done in context of a foods in order to correct this energy imbalance.40 social setting (small bands of individuals out hunting or foraging). Exercising with one or more partners im- proves adherence and mood.23 CHARACTERISTICS OF A HUNTER-GATHERER 8. Except for the very young and the very old, all individ- FITNESS PROGRAM uals were, by necessity, physically active almost their 1. A large amount of background daily light-to-moderate entire lives. activity such as walking was required. Although the distances covered would have varied widely, most esti- References mates indicate average daily distances covered were in 1. Nader PR, Bradley RH, Houts RM, McRitchie SL, O’Brien M. Mod- erate-to-vigorous physical activity from ages 9 to 15 years. JAMA. the range of 6 to 16 km. The hunter-gatherers’ daily 2008;300:295-305. energy expenditures for physical activity typically were 2. Booth FW, Laye MJ, Lees SJ, Rector RS, Thyfault JP. Reduced at least 800 to 1200 kcal,41 or about 3 to 5 times more physical activity and risk of chronic disease: the biology behind the than the average American adult today. consequences. Eur J Appl Physiol. 2008;102:381-390. 2. Hard days were typically followed by an easier day. 3. Booth FW, Lees SJ. Fundamental questions about genes, inactivity, and chronic diseases. Physiol Genomics. 2007;28:146-157. Ample time for rest, relaxation, and sleep was generally 4. Cordain L, Friel J. The Paleo Diet for Athletes: A Nutritional available to ensure complete recovery after strenuous Formula for Peak Athletic Performance. New York: Rodale Books; exertion. 2005. 3. Walking and running were done on natural surfaces such 5. Sandvik L, Erikssen J, Thaulow E, Erikssen G, Mundal R, Rodahl K. as grass and dirt, often over uneven ground. Concrete Physical fitness as a predictor of mortality among healthy, middle-aged Norwegian men. N Engl J Med. 1993;328:533-537. and asphalt surfaces are largely foreign to our genetic 6. Kokkinos P, Myers J, Kokkinos JP, et al. Exercise capacity and identity. mortality in black and white men. Circulation. 2008;117:614-622. 4. Interval training sessions, involving intermittent bursts 7. Byberg L, Melhus H, Gedeborg R, et al. Total mortality after changes of moderate- to high-level intensity exercise with inter- in leisure time physical activity in 50 year old men: 35 year follow-up vening periods of rest and recovery, should be performed of population based cohort. BMJ. 2009;338:b688. 8. Hill A, Ward S, Deino A, Curtis G, Drake R. Earliest Homo. Nature. once or twice per week. 1992;355(6362):719-722. 5. Regular sessions of weight training and other strength 9. Fenner JN. Cross-cultural estimation of the human generation interval and flexibility building exercises are essential for opti- for use in genetics-based population divergence studies. Am J Phys mizing musculoskeletal and general health and fitness. Anthropol. 2005;128:415-423. 1086 The American Journal of Medicine, Vol 123, No 12, December 2010 10. Tremblay MS, Esliger DW, Copeland JL, Barnes JD, Bassett DR. 25. Lee JH, O’Keefe JH, Bell D, Hensrud DD, Holick MF. Vitamin D Moving forward by looking back: lessons learned from long-lost deficiency an important, common, and easily treatable cardiovascular lifestyles. Appl Physiol Nutr Metab. 2008;33:836-842. risk factor? J Am Coll Cardiol. 2008;52:1949-1956. 11. Bassett DR. Physical activity of Canadian and American children: a 26. Berman MG, Jonides J, Kaplan S. The cognitive benefits of interacting focus on youth in Amish, Mennonite, and modern cultures. Appl with nature. Psychol Sci. 2008;19:1207-1212. Physiol Nutr Metab. 2008;33:831-835. 27. Simonsick EM, Guralnik JM, Volpato S, Balfour J, Fried LP. Just get 12. O’Keefe JH Jr, Cordain L. Cardiovascular disease resulting from a diet out the door! Importance of walking outside the home for maintaining and lifestyle at odds with our Paleolithic genome: how to become a mobility: findings from the women’s health and aging study. J Am 21st-century hunter-gatherer. Mayo Clin Proc. 2004;79:101-108. Geriatr Soc. 2005;53:198-203. 13. Frassetto LA, Schloetter M, Mietus-Synder M, Morris RC Jr, Sebas- 28. Hurtado AM, Hawkes K, Hill K, Kaplan H. Female subsistence strat- tian A. Metabolic and physiologic improvements from consuming a egies among Ache hunter-gatherers of Eastern Paraguay. Hum Ecol. paleolithic, hunter-gatherer type diet. Eur J Clin Nutr. 2009;63:947- 1985;13:1-28. 955. 29. Panter-Brick C. Sexual division of labor: energetic and evolutionary 14. Eaton SB, Konner M, Shostak M. Stone agers in the fast lane: chronic scenarios. Am J Hum Biol. 2002;14:627-640. degenerative diseases in evolutionary perspective. Am J Med. 1988; 30. Bowerman WJ, Harris WE. Jogging: A Medically Approved Fitness 84:739-749. Program for All Ages. New York: Grossett and Dunlap; 1967. 15. Cordain L, Gotshall RW, Eaton SB. Evolutionary aspects of exercise. 31. McArdle WD, Katch FI, Katch VL. Exercise Physiology: Energy, World Rev Nutr Diet. 1997;81:49-60. Nutrition and Human Performance. Philadelphia, PA: Lea & Febiger; 1991:421-451. 16. Eaton SB, Shostak M, Konner M. The first fitness formula. In: The 32. Loy SF, Hoffmann JJ, Holland GJ. Benefits and practical use of Paleolithic Prescription. New York: Harper & Row; 1988:168-199. cross-training in sports. Sports Med. 1995;19:1-8. 17. Haskell WL, Lee IM, Pate RR, et al. Physical activity and public 33. White LJ, Dressendorfer RH, Muller SM, Ferguson MA. Effectiveness health: updated recommendation for adults from the American College of cycle cross-training between competitive seasons in female distance of Sports Medicine and the American Heart Association. Circulation. runners. J Strength Cond Res. 2003;17:319-323. 2007;116:1081-1093. 34. Kraemer WJ, Ratamess NA, French DN. Resistance training for health 18. Johnson JL, Slentz CA, Houmard JA, et al. Exercise training amount and performance. Curr Sports Med Rep. 2002;1:165-171. and intensity effects on metabolic syndrome (from Studies of a Tar- 35. Goel R, Majeed F, Vogel R, et al. Exercise-induced hypertension, geted Risk Reduction Intervention through Defined Exercise). Am J endothelial dysfunction, and coronary artery disease in a marathon Cardiol. 2007;100:1759-1766. runner. Am J Cardiol. 2007;99:743-744. 19. Jakicic JM, Marcus BH, Lang W, Janney C. Effect of exercise on 36. Fortescue EB, Shin AY, Greenes DS, et al. Cardiac troponin increases 24-month weight loss maintenance in overweight women. Arch Intern among runners in the Boston Marathon. Ann Emerg Med. 2007;49: Med. 2008;168:1550-1559; discussion 1559-1560. 137-143, 143.e1. 20. Tudor-Locke C, Bassett DR Jr. How many steps/day are enough? 37. Hubble KM, Fatovich DM, Grasko JM, Vasikaran SD. Cardiac tropo- Preliminary pedometer indices for public health. Sports Med. 2004; nin increases among marathon runners in the Perth Marathon: the 34:1-8. Troponin in Marathons (TRIM) study. Med J Aust. 2009;190:91-93. 21. Sigal RJ, Kenny GP, Boule NG, et al. Effects of aerobic training, 38. Jassal DS, Moffat D, Krahn J, et al. Cardiac injury markers in non-elite resistance training, or both on glycemic control in type 2 diabetes: a marathon runners. Int J Sports Med. 2009;30:75-79. randomized trial. Ann Intern Med. 2007;147:357-369. 39. Middleton N, Shave R, George K, et al. Altered left ventricular 22. Trapp EG, Chisholm DJ, Freund J, Boutcher SH. The effects of diastolic filling following a marathon is a reproducible phenomenon. high-intensity intermittent exercise training on fat loss and fasting Int J Cardiol. 2007;122:87-89. insulin levels of young women. Int J Obes (Lond). 2008;32:684-691. 40. O’Keefe JH, Gheewala NM, O’Keefe JO. Dietary strategies for im- 23. Lavie CJ, Thomas RJ, Squires RW, Allison TG, Milani RV. Exercise proving post-prandial glucose, lipids, inflammation, and cardiovascu- training and cardiac rehabilitation in primary and secondary prevention lar health. J Am Coll Cardiol. 2008;51:249-255. of coronary heart disease. Mayo Clin Proc. 2009;84:373-383. 41. Cordain L, Gotshall RW, Eaton SB, Eaton SB 3rd. Physical activity, 24. Peplonska B, Lissowska J, Hartman TJ, et al. Adulthood lifetime energy expenditure and fitness: an evolutionary perspective. Int physical activity and breast cancer. Epidemiology. 2008;19:226-236. J Sports Med. 1998;19:328-335.