Let me introduce myself. My name is Mark Sisson. I’m 63 years young. I live and work in Malibu, California. In a past life I was a professional marathoner and triathlete. Now my life goal is to help 100 million people get healthy. I started this blog in 2006 to empower people to take full responsibility for their own health and enjoyment of life by investigating, discussing, and critically rethinking everything we’ve assumed to be true about health and wellness...
“Eccentric training has been shown to produce greater muscle hypertrophy than concentric training as a result of greater ability for maximal force generating capacity during eccentric contractions.” – J.P. Farthing, University of Saskatchewan
In a guest post a few weeks ago, I mentioned that I’d be back to talk more about research supporting the Primal principle of “lifting heavy things.” Let’s do it.
Women Won’t Look Like Men and Men Won’t Look Like Bulldogs
Before digging into the details about lifting or lowering anything, it is important to address a common fear that exercising with heavy things makes women look like men and men look like bulldogs. The best way to address this fear is to understand our biology. Everyone has a gene called GDF-8, and that controls a substance called myostatin, which controls the amount of muscle we have and how much muscles develop naturally. The base levels of myostatin and muscle in basically all women and most men make it impossible for them to naturally build bulky muscles. It does not matter how much resistance we use. The majority of us—especially women—do not have the genes to build bulky muscles via any form of exercise.
Myostatin (GDF-8), a member of the transforming growth factor-beta (TGF-?) superfamily of secreted growth and differentiation factors, is a negative regulator of skeletal muscle growth. Loss of myostatin function is associated with an increase in muscle mass in mice, cows, and humans.
– M.N. Elkasrawy, Medical College of Georgia
I find it useful to think about muscle size like muscle speed. Few people are fast because few people have “fast genes.” No matter how much most people run, they will never get faster than their genes allow. However, if people do have the genetics for speed, they will naturally be faster than most people without ever training. Similarly, few people can become bulky because few people—particularly women—have “bulky genes.” No matter how much most people resistance train, they will never develop more muscle than their genes allow.
With our minds at ease let’s move on to…
Why Conventional Wisdom Fails, While Lifting Heavy Things Works
These findings indicate that type II muscle has a previously unappreciated role in regulating whole-body metabolism through its ability to alter the metabolic properties of remote tissues. These data also suggest that strength training, in addition to the widely prescribed therapy of endurance training, may be of particular benefit to overweight individuals.
– Y. Izumiya, Boston University
Why does conventional wisdom tell us to exercise via jogging, riding a bike, etc. for an hour per day? Because these activities involve our large leg muscles. The thinking is that the more muscle exercised, the better our results. At least conventional wisdom (CW) got that much right.
But here’s where CW comes up short: It is physiologically impossible for any amount of CW’s “cardio” to actually exercise as much muscle as possible. In fact, CW exercise approaches only activate one of the four types of muscle fibers we have. Doing more of it simply works that one type of muscle fiber over and over. And sadly, the singular type of muscle fiber it exercises is the least effective at triggering the hormonal reaction required to most efficiently burn body fat while preserving lean tissue…aka the hormonal reaction that enables us to look lean and fit rather than like a near-death bag of bones.
To dig a bit deeper into why CW fails, and lifting heavy things succeeds, we need to understand four principles of how our muscles function:
We have different types of muscle fibers which do different things.
The more force a fiber generates, the less endurance it has.
We cannot work more forceful fibers without also working less forceful fibers.
The more forceful a fiber, the more metabolic benefit we get from exercising it.
Different Types of Fibers, Different Levels of Force and Endurance
Like we have different muscles to do different things, we have different muscle fibers to do different things. This is critical to understand because just as we select specific exercises to work specific muscles, we can select specific exercises to work specific muscle fibers. For example, type 1 muscle fibers allow us to do low-force work for a long period of time. We work them when we do an hour of CW’s “cardio.” In contrast, our type 2b muscle fibers allow us to do a high-force work for a short period of time. We work them when we lift heavy things for a few seconds.
Well, that’s not exactly true…
Working More Forceful Fibers Works All Fibers and Is Uniquely Beneficial
First, high-intensity exercise training induces secretion of lipolytic [fat-burning] hormones including growth hormone and epinephrine, which may facilitate greater post-exercise energy expenditure and fat oxidation. Second, it has been reported that under equivalent levels of energy expenditure high-intensity exercise training favors a greater negative energy balance compared to low-intensity exercise training.”
– B.A. Irving, University of Virginia
When we do high-force and short-duration exercise we don’t exclusively work our type 2b fibers. We work all of our less forceful fibers and our type 2b fibers. We try to lift something heavy, and our muscles first try to generate enough force with our weakest type 1 fibers. Those do not generate enough force, so our muscles also activate our more forceful type 2a fibers to help. Still not enough? Keep the type 1 and type 2a fibers going and add the stronger type 2x fibers. More? Don’t stop working the other three and bring in our most powerful type 2b fibers. Thanks to this cumulative activation of all of our muscle fibers (known as orderly recruitment in physiology circles), Primal exercise actually enables us to do what CW attempts to do: exercise the most muscle possible.
Even better, recent research reveals that exercising our most forceful type 2b muscle fibers is uniquely metabolically beneficial. For instance, Y. Izumiya of Boston University studied mice in a clinical setting and learned that the development of type 2b muscle fibers:
…lead to a reduction in accumulated white adipose tissue and improvements in metabolic parameters independent of physical activity or changes in the level of food intake. These effects occur independently of muscle oxidative capacity and are associated with increases in fatty acid metabolism in liver…The results from the current study indicate that modest increases in type 2b skeletal muscle mass can have a profound systemic effect on whole-body metabolism and adipose mass.
Dr. Izumiya continues extolling type 2b muscle fiber development with:
The metabolic improvement in this model cannot be entirely explained by a reduction in fat-pad mass, indicating that type II muscle counteracts the actions of excess adipose tissue on whole-body metabolism. These findings indicate that type II muscle has a previously unappreciated role in regulating whole-body metabolism through its ability to alter the metabolic properties of remote tissues.
He also states that these muscle fibers improved “insulin sensitivity and [caused] reductions in blood glucose, insulin, and leptin levels,” and that, “these effects occurred despite a reduction in physical activity.” Sign me up!
When it comes to long-term fat loss and lean tissue preservation, CW, common sense, and science all agree that the more muscle we exercise the better. The issue is how we actually do that. It’s literally impossible via low-force CW exercise. Our muscles just don’t work that way. We need to work with more force. We need to exercise Primally. We need to lift heavy things—and as we’ll see next—lower heavy things.
Lowering Heavy Things to Maximize Muscular Force
Every exercise has two parts: lifting the resistance and lowering the resistance. Lifting the resistance is called the concentric portion of the exercise. Concentric is when the muscle contracts.Lowering the resistance is called the eccentric portion of the exercise. Eccentric is when the muscle extends. Lifting weights—the concentric action—gets the most attention, but research shows that lowering weights—the eccentric action—can get us more results since safely and slowly lowering heavy things enables us to generate more force. M. Roig at the University of British Columbia found that “Eccentric training performed at high intensities was shown to be more effective in promoting increases in muscle.” Why? E.J. Higbie at University of Georgia tells us, “Greater maximum force can be developed during maximal eccentric muscle actions than during concentric.” And N.D. Reeves at Manchester Metropolitan University echoes with, “Muscles are capable of developing much higher forces when they contract eccentrically compared with when they contract concentrically.”
If you’d like to see how much stronger you are “on the way down,” hop on a seated row or chest press machine (or any exercise that moves on a horizontal plane—to eliminate the influence of gravity) and select a weight that you cannot lift with one arm but can lift easily with two arms. Lift it with two arms and cautiously relax one arm and observe as you are able to lower the resistance with one arm. You couldn’t lift the weight with one arm, but you could lower it with one arm because your muscles are literally stronger on the way down. You muscles can generate more force eccentrically—when lowering heavy things—than they can concentrically—when lifting things.
Over the past several decades, numerous studies have established that eccentric contractions can maximize the force exerted and the work performed by muscle…that they can attenuate the mechanical effects of impact forces; and that they enhance the [good] tissue damage associated with exercise.
– R.M. Enoka, Cleveland Clinic Foundation
The takeaway here is not to stop lifting heavy things. It’s to note that our muscles generate more force eccentrically, so lowering heavy things may enable us to activate even more of our uniquely helpful type 2b fibers. It’s another great exercise option for us. Here’s how to give eccentric exercise a whirl.
How to Lower Heavy Things
Get warmed up by walking briskly or riding a bike for a few minutes.
Pick a resistance you cannot lift with one arm or leg—depending on the exercise—but can easily lift with both arms or legs. Let’s say 50 pounds.
Lift the resistance with both arms or legs. Each arm or leg is lifting about half the weight—25 pounds in this example.
Lower the resistance with only one arm or leg for ten seconds. Each arm or leg slowly—count to 10—lowers all the weight—50 pounds in our example.
Repeat until it is impossible to lower the resistance with only one arm or leg for ten seconds. If this takes more than six repetitions, gradually add resistance until it only takes six repetitions.
Smile because previously you would have stopped doing this exercise when you could no longer lift 25 pounds per limb, and now you are stopping when you can no longer lower 50 pounds per limb.
Eccentric training resulted in greater hypertrophy than concentric training. We conclude that eccentric fast training is the most effective for muscle hypertrophy and strength gain.
– J.P. Farthing, University of Saskatchewan
With this technique we can lower heavy things in the comfort of our own home or at the gym. But before we go get eccentric, there are two important rules to keep in mind.
First, if we choose to exercise eccentrically on machines at our local gym, then we should only use machines that work both of our arms or both of our legs together. This is the only way to have less resistance on the way up and more on the way down. If we pick machines working our arms and legs independently, we will lift and lower the same amount of resistance. That defeats the whole purpose. Think about it this way. Say you grab a gallon of milk in each hand, lift them above your head, and then drop the one in your right hand to increase the resistance for your left hand. That does not work because lifting milk jugs works your arms independently. However, if you lifted one milk jug with each arm, but then lowered both jugs with only your left arm, you would lower more resistance with your left arm than you lifted with your left arm. Resistance training machines which work both of our arms or both of our legs together do the same thing.
Exercise with a maximal-eccentric component can induce increases in muscle…with shorter durations of work than other modes.
– M. Wernbom, Göteborg University
Second, exercise eccentrically only when little if any balance is needed. Just as you would not pick up a giant flat-screen TV with two hands and then let go with one, you should only exercise eccentrically when no balance is needed.
Putting these two rules together, we could:
Do a push-up with our knees on the floor (to reduce the resistance), and then lift our knees and lower ourselves (to increase the resistance). Our arms worktogether to lift a shared source of resistance (our body), and little if any balance is needed.
Stand up and then do a body weight squat down—while hanging on to something for balance—with one leg. Stand back up with two legs.
Stand on something to assist ourselves into getting to the top position of a pull-up, and then lower our full bodyweight down. Lift ourselves back up with the help of our legs.
You can imagine all sorts of ways to adapt these principles to any sort of workout. Just apply these three simple points:
Lift resistance with both arms/legs. Lower resistance slowly with one arm/leg.
Pick a shared source of resistance.
Exercise eccentrically only when little if any balance is required.
As you start experimenting with lowering heavy things, keep in mind that…
More Muscle Worked Means More Recovery Time Needed
If we cut grass lower, we can mow our lawn less often. That is not some too-good-to-be-true gimmick. That is common sense. The more grass we cut off, the more time is needed to grow it back. Similarly, if we’re working more muscle fibers by exercising with more force, we can exercise less often. The more muscle fibers we exercise, the more time we need to recover.
How long your muscles take to recover is a great way to tell if you are exercising your type 2b muscle fibers. If you are able to lower heavy things on Monday and then lower the same heavy thing a day or two later, then your first workout didn’t work your type 2b fibers. If it did, those fibers will not be ready to go again one, two, three, four, or even five days later. Research reveals that type 2b muscle fibers need at least six days to recover.
Damage produced by eccentric exercise was more persistent than previously reported, indicating that more than 10 days may be necessary for recovery of muscle ultrastructure and carbohydrate reserves.
– K.P. O’Reilly, in the Journal of Applied Physiology
This is not to say that we should sit around in-between lowering heavy things. We should always heed the Primal principle to “move around a lot at a slow pace.” The point here is that if we’re exercising eccentrically effectively, we’ll be too sore to do much more than moving around at a slow pace for at least a few days afterward.
My gym has two-pound weights. If you are using two-pound weights, how did you even open the door to the gym? What’s your dream? To pump up and open your mail?
– Dave Attell, Comic
CW’s “cardio” doesn’t work well because it requires little force and therefore works relatively little muscle. Lifting heavy things works because it requires a lot of force and therefore works a lot of muscle and our uniquely metabolically beneficial type 2b muscle fibers. Lowering heavy things can enable us to generate even more force and can be an excellent addition to a Primal lifestyle. Of course, do what works for you. My hope is that this research provides you with another option to assist with your long-term health and fitness goals.
[|de Meijer J] (1998-05-01). Hormone sensitive lipase: structure, function and regulation. demeijer.com. http://demeijer.com/biology/scriptie.pdf. Retrieved 02-09-2010. A thesis written at the Biochemical Physiology Research Group, Department of Experimental Zoology, University of Utrecht, under supervision of dr. W. J. A. van Marrewijk
Ades PA, Savage PD, Brochu M, Tischler MD, Lee NM, Poehlman ET. Resistance training increases total daily energy expenditure in disabled older women with coronary heart disease. J Appl Physiol. 2005 Apr;98(4):1280-5. PubMed PMID:15772059.
Ballor, D.L., Becque, M.D., & Katch, V.L. (1987). Metabolic responses during hydraulic resistance training. Medicine & Science in Sports & Exercise 19, 363-367.
Björntorp P. The regulation of adipose tissue distribution in humans. Int J Obes Relat Metab Disord. 1996 Apr;20(4):291-302. Review. PubMed PMID: 8680455.
Blackburn GL, Wilson GT, Kanders BS, Stein LJ, Lavin PT, Adler J, Brownell KD. Weight cycling: The experience of human dieters. Am J Clin Nutr. 1989 May;49(5 Suppl):1105-9. PubMed PMID: 2718940.
Farthing JP, Chilibeck PD. The effects of eccentric and concentric training at different velocities on muscle hypertrophy. Eur J Appl Physiol. 2003 Aug;89(6):578-86. Epub 2003 May 17. PubMed PMID: 12756571.
Fridén J; Sjöström M; Ekblom B. Myofibrillar damage following intense eccentric exercise in man. Int J Sports Med. 1983; 4(3):170-6 (ISSN: 0172-4622)
Fry AC. The Role of Training Intensity in Resistance training Overtraining and Overreaching. In: Kreider RB. Fry AC, O’Toole ML, editors. Overtraining in sport. Champaign (IL): Human Kinetics, 1998: 107-27.
Gilliat-Wimberly M, Manore MM, Woolf K, Swan PD, Carroll SS. Effects of habitual physical activity on the resting metabolic rates and body compositions of women aged 35 to 50 years. J Am Diet Assoc. 2001 Oct;101(10):1181-8. PubMed PMID: 11678489.
Golden CL, Dudley GA. Strength after bouts of eccentric or concentric actions. Med Sci Sports Exerc. 1992 Aug;24(8):926-33. PubMed PMID: 1406179.
Golden CL, Graves JE, Buchanan P, Dudly G. Eccentric and Concentric Strength After Repeated Bouts of Intense Exercise. Med Sci Sports Exerc 1991; 23 (Suppl): 655A.
Goto K, Ishii N, Kizuka T, Takamatsu K. The impact of metabolic stress on hormonal responses and muscular adaptations. Med Sci Sports Exerc. 2005 Jun;37(6):955-63. PubMed PMID: 15947720.
Gotshalk, L.A., et.al. (1996). Pituitary-gonadal hormonal responses of multi-set vs. single -set resistance training. Journal of Strength and Conditioning Research. 10(4):286.
Harman SM, Metter EJ, Tobin JD, Pearson J, Blackman MR; Baltimore Longitudinal Study of Aging. Longitudinal effects of aging on serum total and free testosterone levels in healthy men. Baltimore Longitudinal Study of Aging. J Clin Endocrinol Metab. 2001 Feb;86(2):724-31. PubMed PMID: 11158037.
Harrison BC, Leinwand LA. Fighting fat with muscle: bulking up to slim down. Cell Metab. 2008 Feb;7(2):97-8. Review. PubMed PMID: 18249167.
Hather BM, Tesch PA, Buchanan P, Dudley GA. Influence of eccentric actions on skeletal muscle adaptations to resistance training. Acta Physiol Scand. 1991 Oct;143(2):177-85. PubMed PMID: 1835816.
Henneman E, Olson Cb. Relations Between Structure And Function In the Design of Skeletal Muscles. J Neurophysiol. 1965 May;28:581-98. Pubmed Pmid: 14328455.
Henneman E, Somjen G, Carpenter DO. Excitability and inhibitability of motoneurons of different sizes. J Neurophysiol. 1965 May;28(3):599-620. PubMed PMID: 5835487.
Henneman E, Somjen G, Carpenter Do. Functional Significance of Cell Size In Spinal Motoneurons. J Neurophysiol. 1965 May;28:560-80. Pubmed Pmid: 14328454.
Higbie EJ, Cureton KJ, Warren GL 3rd, Prior BM. Effects of concentric and eccentric training on muscle strength, cross-sectional area, and neural activation. J Appl Physiol. 1996 Nov;81(5):2173-81. PubMed PMID: 8941543.
Hortobágyi T, Dempsey L, Fraser D, Zheng D, Hamilton G, Lambert J, Dohm L. Changes in muscle strength, muscle fibre size and myofibrillar gene expression after immobilization and retraining in humans. J Physiol. 2000 Apr 1;524 Pt 1:293-304. PubMed PMID: 10747199; PubMed Central PMCID: PMC2269843.
Hunter GR, Wetzstein CJ, Fields DA, Brown A, Bamman MM. Resistance training increases total energy expenditure and free-living physical activity in older adults. J Appl Physiol. 2000 Sep;89(3):977-84. PubMed PMID: 10956341.
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
Ivy JL, Zderic TW, Fogt DL. Prevention and treatment of non-insulin-dependent diabetes mellitus. Exerc Sport Sci Rev. 1999;27:1-35. Review. PubMed PMID: 10791012.
Izumiya Y, Hopkins T, Morris C, Sato K, Zeng L, Viereck J, Hamilton JA, Ouchi N, LeBrasseur NK, Walsh K. Fast/Glycolytic muscle fiber growth reduces fat mass and improves metabolic parameters in obese mice. Cell Metab. 2008 Feb;7(2):159-72. PubMed PMID: 18249175.
Katz B. The relation between force and speed in muscular contraction. J Physiol. 1939 Jun 14;96(1):45-64. PubMed PMID: 16995114; PubMed Central PMCID:PMC1393840.
Keogh, J. W. L., G. J. Wilson, And R. P. Weatherby. A Crosssectional Comparison of Different Resistance Training Techniques In the Bench Press. J. Strength Cond. Res. 13:247–258, 1999.
Komi PV, Buskirk ER. Effect of eccentric and concentric muscle conditioning on tension and electrical activity of human muscle. Ergonomics. 1972 Jul;15(4):417-34. PubMed PMID: 4634421.
Kraemer WJ, Ratamess NA. Fundamentals of resistance training: progression and exercise prescription. Med Sci Sports Exerc. 2004 Apr;36(4):674-88. Review. PubMed PMID: 15064596.
Kraemer WJ, Ratamess NA. Hormonal responses and adaptations to resistance training and training. Sports Med. 2005;35(4):339-61. Review. PubMed PMID:15831061.
Kraemer WJ. Endocrine responses to resistance training. Med Sci Sports Exerc. 1988 Oct;20(5 Suppl):S152-7. Review. PubMed PMID: 3057315.
Kraemer,W.J. & Ratamess, N.A. (2004). Fundamentals of resistance training: progression and exercise prescription. Medicine & Science in Sports & Exercise 36, 674-688.
Kraemer,W.J. & Ratamess, N.A. (2005). Hormonal responses and adaptations to resistance training and training. Sports Medicine 35, 339-361.
Lee SJ. Regulation of muscle mass by myostatin. Annu Rev Cell Dev Biol. 2004;20:61-86. Review. PubMed PMID: 15473835.
Leibel RL, Rosenbaum M, Hirsch J. Changes in energy expenditure resulting from altered body weight. N Engl J Med. 1995 Mar 9;332(10):621-8. Erratum in: N Engl J Med 1995 Aug 10;333(6):399. PubMed PMID: 7632212.
Little, John, and Doug Mcguff. Body by Science: A Research Based Program to Get the Results You Want in 12 Minutes a Week. 1 ed. New York: McGraw-Hill, 2008.
Mendell LM. The size principle: a rule describing the recruitment of motoneurons. J Neurophysiol. 2005 Jun;93(6):3024-6. PubMed PMID: 15914463.
Milner-Brown HS, Stein RB, Yemm R. The orderly recruitment of human motor units during voluntary isometric contractions. J Physiol. 1973 Apr;230(2):359-70. PubMed PMID: 4350770; PubMed Central PMCID: PMC1350367.
Nardone A, Romanò C, Schieppati M. Selective recruitment of high-threshold human motor units during voluntary isotonic lengthening of active muscles. J Physiol. 1989 Feb;409:451-71. PubMed PMID: 2585297; PubMed Central PMCID: PMC1190454.
Newham DJ, McPhail G, Mills KR, Edwards RH. Ultrastructural changes after concentric and eccentric contractions of human muscle. J Neurol Sci. 1983 Sep;61(1):109-22. PubMed PMID: 6631446.
Obesity and leanness. Basic aspects. Stock, M., Rothwell, N., Author Affiliation: Dep. Physiology, St. George’s Hospital Medical School, London Univ., London, UK.
Rasmussen BB, Wolfe RR. Regulation of fatty acid oxidation in skeletal muscle. Annu Rev Nutr. 1999;19:463-84. Review. PubMed PMID: 10448533.
Reeves ND, Maganaris CN, Longo S, Narici MV. Differential adaptations to eccentric versus conventional resistance training in older humans. Exp Physiol. 2009 Jul;94(7):825-33. Epub 2009 Apr 24. PubMed PMID: 19395657.
Roig M, O’Brien K, Kirk G, Murray R, McKinnon P, Shadgan B, Reid WD. The effects of eccentric versus concentric resistance training on muscle strength and mass in healthy adults: a systematic review with meta-analysis. Br J Sports Med. 2009
Saladin, Kenneth. Anatomy and Physiology: The Unity of Form and Function. 5 ed. New York: McGraw-Hill Science/Engineering/Math, 2009. Print.
Schutz Y, Jequier E. Resting Energy Expenditure, thermic Effect of Food, and Total Energy Expenditure In: Bray GA, Couchard d, James WP, eds. Handbook of Obesity. New York: Marcel Dekker, 1997: 443-456.
Seger, JY, Arvidson B, and Thorstensson A. Specific effects of eccentric and concentric training on muscle strength and morphology in humans. Eur J Appl Physiol 79: 49-57, 1998.
Simoneau JA. Kelly D. Skeletal Muscle and Obesity In: Bray GA, Couchard d, James WP, eds. Handbook of Obesity. New York: Marcel Dekker, 1997: 539-553.
Snyder PJ. Decreasing testosterone with increasing age: more factors, more questions. J Clin Endocrinol Metab. 2008 Jul;93(7):2477-8. PubMed PMID: 18617703.
Staley, Charles. Muscle Logic : Escalating Density Training. Emmaus, Pa.: Rodale Books, 2005. Print. Poehlman ET, Mepoundy C. Resistance training and energy balance. Int J Sport Nutr. 1998 Jun;8(2):143-59. Review. PubMed PMID: 9637193.
Stárka L, Pospísilová H, Hill M. Free testosterone and free dihydrotestosterone throughout the life span of men. J Steroid Biochem Mol Biol. 2009 Aug;116(1-2):118-20. Epub 2009 May 22. PubMed PMID: 19465126.
Tomberlin JP, Basford JR, Schwen EE, Orte PA, Scott SC, Laughman RK, Ilstrup DM. Comparative study of isokinetic eccentric and concentric quadriceps training. J Orthop Sports Phys ther. 1991;14(1):31-6. PubMed PMID: 18796832.
van Pelt RE, Dinneno FA, Seals DR, Jones PP. Age-related decline in RMR in physically active men: relation to exercise volume and energy intake. Am J Physiol Endocrinol Metab. 2001 Sep;281(3):E633-9. PubMed PMID: 11500320.
van Pelt RE, Jones PP, Davy KP, Desouza CA, Tanaka H, Davy BM, Seals DR. Regular exercise and the age-related decline in resting metabolic rate in women. J Clin Endocrinol Metab. 1997 Oct;82(10):3208-12. PubMed PMID: 9329340.
Vikne H, Refsnes PE, Ekmark M, Medbø JI, Gundersen V, Gundersen K. Muscular performance after concentric and eccentric exercise in trained men. Med Sci Sports Exerc. 2006 Oct;38(10):1770-81. PubMed PMID: 17019299.
Watkins, P.H (2010) Augmented Eccentric Loading: Theoretical and Practical Applications for the Strength and Conditioning Professional. Professional Strength and Conditioning, UKSCA Issue 17, pp4-12
Weigle DS, Sande KJ, Iverius PH, Monsen ER, Brunzell JD. Weight loss leads to a marked decrease in nonresting energy expenditure in ambulatory human subjects. Metabolism. 1988 Oct;37(10):930-6. PubMed PMID: 3173112.
Wernbom M, Augustsson J, Thomeé R. The influence of frequency, intensity, volume and mode of strength training on whole muscle cross-sectional area in humans. Sports Med. 2007;37(3):225-64. Review. PubMed PMID: 17326698.
Wilcox G. Insulin and insulin resistance. Clin Biochem Rev. 2005 May;26(2):19-39. PubMed PMID: 16278749; PubMed Central PMCID: PMC1204764.
Yeaman SJ. Hormone-sensitive lipase–new roles for an old enzyme. Biochem J. 2004 Apr 1;379(Pt 1):11-22. Review. PubMed PMID: 14725507; PubMed Central PMCID: PMC1224062.