Rule 2: Put Strength First

Regardless of your age, gender, or physical condition, lean muscle means a better body. Such lean muscle is most efficiently developed through strength training. There are many kinds of strength training, but for the purposes of this book, we'll define strength training as movements hard enough to do that most people have to stop after roughly 20 repetitions. Movements that can be sustained for more than 20 repetitions without pause we will call endurance training, a category that includes running or cardiovascular exercise. Many people tend to avoid strength training, perhaps because it is more intense than the relatively mild endurance activities of steady jogging, bicycling, or walking, but strength training has unique benefits that can over time literally change the shape and form of your body in a way milder cardiovascular exercise does not. To make sure you get the benefit of strength training, this book puts it first by including it in a workout that balances cardiovascular exercise with real-life, weight-bearing strengthening movements that researchers say best stimulate real-life improvement in muscle, tendon (which connects muscle to bone), ligament (which connects bone to other bone), and bone.

It is hard to overstate the importance of muscle. When you build muscle, you become strong, toned, and alive with energy. Your lean muscle powers you through the day and makes you injury-resistant by taking load and stress better than any other tissue. Fat weight is dead weight, but muscle weight is live weight. It keeps you youthful as well: one of the most conspicuous signs of youth is muscle tone. The vastus lateralis (lateral thigh) muscle of an 80-year-old male is significantly smaller, by more than 30 percent, than the vastus lateralis muscle of a 20-year-old male, as measured by cross sectional area of key strength-specialized muscle fibers.[1] Matching this measurable decline in size is a decline in muscle strength of the average 20-year-old to the average 80-year-old, also of about 30 percent.[2] While some age-related changes are unavoidable, much of this decline may come from simply not exercising: a large-scale survey of 23,000 adults of all ages also shows decline, over a lifetime, of frequency of vigorous physical activity: 60-year-olds engaged in vigorous activities much less frequently each week than did 18-to-44-year-olds. How much less frequently? Also by 30 percent or more.[3] Muscle really is a fountain of youth. Build it by doing strength training in your workout, doing it first in the workout to get it done and out of the way early.

Even if you're overweight, building muscle still should be a top priority because muscle so powerfully burns fat. Although it weighs 1.2 times more than fat, muscle more than make up for its increased mass by burning, even at rest,[4] many more calories per hour. Lean muscle being associated with higher calorie-burning capacity even at rest, adding just a few pounds of lean muscle might you a new way to burn more calories each day, each night, and each month, helping gradually burn more fat away. In this way muscle raises your metabolism, or the rate you burn calories. The more muscle you have, the higher your metabolism. Building muscle turns up your metabolic thermostat, helping keep fat off your body.

Given unlimited time, you could experiment with all kinds of ways to build muscle, like with abdominal crunches, ball exercises, or smaller movements focusing specifically on just a few muscles at one time. But with over 600 skeletal muscles in your body, it probably makes sense to focus more on exercises that simultaneously involve large numbers of them at once, especially if you have limited time for working out. Large movements—pushing, pulling, and lifting—can train your body more efficiently because they demand work from more muscles. Instead of doing hundreds of exercises for each of your 600 muscles, large movements many muscles at the same time. A good strength-building exercise program includes plenty of large movements in order to be efficient.

The importance of large movements is the first instance of your tendency to adapt specifically to, and only specifically to, whatever exercise you impose on it, a tendency so ingrained in the human training response that exercise physiologists call it "the law of specificity". Always efficient, your body wastes no energy adapting to overloads it never experiences but changes only in exact response to whatever particular exercise you do. Your body gets better with each workout, but only enough to more efficiently repeat it: you get better at what you do, but only at what you do. Exercise physiologists use the law of specificity to design athletic training programs for every aspect of sport performance.

The law of specificity also suggests that the most improvement in real-life physical performance would come from doing exercises more closely resembling real-life tasks. Real-life movements make you better at real-life physical tasks, like not falling on a slippery floor. True to this law of specificity, exercises requiring you to push, to pull, to lift, and to move across land train you the most efficiently for the pushing, pulling, lifting, and locomotive movement comprising the majority of life's tasks. In one study published in the Journal of Orthopedic and Sports Physical Therapy, 24 healthy adult subjects were divided into two groups, one group doing exercises that closely relate to the real-life task of lifting the body with your legs, deep squats with and without barbells, the other group using special exercise equipment, variable resistance knee extension and hip abduction exercise machines, similar to the kind you see in gyms. The real-life exercise group outperformed the special equipment group, improving leg strength over the course of the study, not only as measured by squat three-repetition maximum, by 31 percent, compared to only 13 percent for the non-weight-bearing group, but also improved in vertical jump height by 10 percent, as opposed to no significant improvement for the special equipment group.[5] The results of this study, and others like it,[6] suggest that for a strength program to be effective, it should include plenty of movements closely related to real life. In other words, a good strength-building exercise program includes plenty of real-life movements in order to be effective.

Finally, some kinds of exercise, called "weight-bearing," are better for strengthening your bones and joints. Whenever you stand, step, or balance your body against gravity, you are bringing weight to bear on your bones and joints. (Neither the knee extension and hip abduction exercise machines used in the study just cited, abdominal crunches, seated-on-ball exercises, nor exercises you can do sitting down are good examples of weight-bearing exercise.) Weight-bearing exercise is good because it provides a type of loading that stimulates your bone to stay thick and strong. Without the regular loading that researchers call "minimal essential strain," your bones thin and weaken. So scarce are these bone-loading types of exercise that by the time most of us reach old age an everyday stress, like landing hard on your foot, can fracture bone. This type of bone weakness, called osteoporosis, is a silent but surprisingly widespread problem: often its first clue is a stress fracture, which more than 25 percent of us experience in sometime in our lives.[7] While a sedentary lifestyle leads to osteoporosis, weight-bearing exercise—introduced gradually to people unused to it—can turn the tide of bone loss. Weight-bearing movement is especially crucial for your back: patients lost one percent of their vertebral bone mass during each week of bed rest in a 1983 London study, and only weight-bearing exercise, in the form of walking, reversed the loss.[8] A related study showed that weight-bearing (standing, stepping, or balancing) had an even greater effect than muscle contractions (pushing or pulling weight on a pulley) in preserving vertebral bone density.[9] Weight-bearing movements stop bone loss by causing bone-producing cells called osteoblasts to migrate to the site of loading, where they lay down new and stronger bone. Perhaps largely because people substantially reduce their weight-bearing exercise as they get older, most lose bone mass at the alarming rate of three to nine percent per decade, with women especially at risk after menopause, when hormonal changes and inactivity combine to cause rapid but undetected bone loss.[10] Ultimately, such bone loss means everyday events can result in large bone fractures and their fatal complications, as with hip fractures, a leading cause of death in old age. Weight-bearing exercise can stop and even reverse this bone loss, even in postmenopausal women, who are at highest risk for it. Postmenopausal women participating in an exercise program that included jumping, running, and strengthening not only increased their bone density but reduced their back pain and lowered their cholesterol as well. Non-exercisers, by contrast, even while taking daily calcium and vitamin D supplements sustained a substantial three percent bone density loss over just two years.[11] The prevalence of osteoporosis and bone's vulnerability to lose density alarmingly fast, even with calcium and vitamin D supplementation, together with the responsiveness of bone to loading, strongly suggests weightbearing exercise as an effective way to make your bones stronger.

Weight-bearing exercise can help not just your bones but also your joints, too. Lacking a direct blood supply, joint cartilage depends on the intermittent compression and decompression of mechanical loading to circulate the synovial fluid within the joint,[12] which nourishes the cartilage and keeps it metabolically active.[13] Weight-bearing activity provides such loading and in so doing, floods the surface of joint cartilage with nutrient-rich synovial fluid.[14] The continued health, strength, and survival of joint cartilage all depend on a variety of loading stresses and strains throughout life.[15],[16] Deprived of such compression and decompression, cartilage slowly deteriorates,[17] resulting in the changes that bring about arthritis.[18] The next Rule, "Add Cardio Often," discusses a specific form of weight-bearing activity, jogging, and presents evidence that suggests jogging does not seem to promote and even may prevent arthritis.

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[1] Lexell J, Taylor CC. Variability in muscle fibre areas in whole human quadriceps muscle: effects of increasing age. J Anat. 1991 Feb;174:239-49.

[2] Klein CS, Rice CL, Marsh GD. Normalized force, activation, and coactivation in the arm muscles of young and old men. J Appl Physiol. 2001 Sep;91(3):1341-9.

[3] Pleis JR, Lucas JW. Summary health statistics for U.S. adults: National Health Interview Survey, 2007. National Center for Health Statistics. Vital Health Stat 10(240). 2009. http://www.cdc.gov/nchs/nhis/physical_activity/pa_statistics.htm

[4] Wang Z, Heshka S, Gallagher D, Boozer CN, Kotler DP, Heymsfield SB. Resting energy expenditure-fat-free mass relationship: new insights provided by body composition modeling. Am J Physiol Endocrinol Metab. 2000 Sep;279(3):E539-45.

[5] Augustsson J, Esko A, Thomee R, Svantesson U. Weight training of the thigh muscles using closed vs. open chain exercises: a comparison of performance enhancement. Journal of Orthopedic Sports Physical Therapy. 1998 Jan;27(1):3-8

[6] Blackburn JR, Morrissey MC. The relationship between open and closed kinetic chain strength of the lower limb and jumping performance. J Orthop Sports Phys Ther. 1998 Jun;27(6):430-5.

[7] World Health Organization press release "Aging and Osteoporosis" April 7, 1999.

[8] Krolner B, Toft B. Vertebral bone loss: an unheeded side effect of therapeutic bed rest. Clinical Science (London). 1983 May;64(5):537-40

[9] Issekutz B, Blizzrad JJ, Birkhead NC, Rodahl K. Effect of prolonged bed rest on urinary calcium output. J. Appl. Physiol. 1966;21(3):1013-1020

[10] Mazess RB. On aging bone loss. Clin Orthop. Clin Orthop. 1982 May;(165):239-52

[11] Kemmler W, Lauber D, Weineck J, Hensen J, Kalender W, Engelke K. Benefits of 2 Years of Intense Exercise on Bone Density, Physical Fitness, and Blood Lipids in Early Postmenopausal Osteopenic Women: Results of the Erlangen Fitness Osteoporosis Prevention Study (EFOPS). Arch Intern Med. 2004 May 24;164(10):1084-1091

[12] Arkill KP, Winlove CP. Solute transport in the deep and calcified zones of articular cartilage. Osteoarthritis Cartilage. 2008 Jun;16(6):708-14.

[13] Quinn TM, Morel V, Meister JJ. Static compression of articular cartilage can reduce solute diffusivity and partitioning: implications for the chondrocyte biological response. J Biomech. 2001 Nov;34(11):1463-9.

[14] The chondrocyte: a cell under pressure. Urban JP. The chondrocyte: a cell under pressure. Br J Rheumatol. 1994 Oct;33(10):901-8.

[15] Carter DR, Wong M. Modelling cartilage mechanobiology. Philos Trans R Soc Lond B Biol Sci. 2003 Sep 29;358(1437):1461-71.

[16] Saadat E, Lan H, Majumdar S, Rempel DM, King KB. Long-term cyclical in vivo loading increases cartilage proteoglycan content in a spatially specific manner: an infrared microspectroscopic imaging and polarized light microscopy study. Arthritis Res Ther. 2006;8(5):R147.

[17] Eckstein F, Hudelmaier M, Putz R. The effects of exercise on human articular cartilage. J Anat. 2006 Apr;208(4):491-512.

[18] Carter DR, Beaupré GS, Wong M, Smith RL, Andriacchi TP, Schurman DJ. The mechanobiology of articular cartilage development and degeneration. Clin Orthop Relat Res. 2004 Oct;(427 Suppl):S69-77.

[19] Gwinup G, Chelvam R, Steinberg T. Thickness of subcutaneous fat and activity of underlying muscles. Annals of Internal Medicine, 1971: 408-11

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