Why Women Should Not Run...Long Distances

Tweet

I know this is probably going to step on some toes but lets dive right into it as its for your good :)

Lets take for instance our friend Jill who runs on the treadmill—day after day, year after year—like she's on a mission. Her body seems to get softer with every mile, and the softer she gets, the more she runs. For her, I feel sympathy, because the world has convinced her that running is the way to stay “slim and toned.”

There’s a Jill in every gym. Spotting them is easy. They’re the women who run for an hour or more every day on the treadmill, setting new distance and/or time goals every week and month. Maybe they’re just interested in their treadmill workouts, maybe they’re training for their fifth fund-raising marathon, or maybe they’re even competing against runners in Finland via some Nike device. Years of running like this has exposed the results, which I’m not going to sugarcoat:

She’s still fat. Actually, she’s gotten fatter.

I’ve tried to rescue her from the clutches of cardio in the past, but my efforts didn’t work until a month ago, when she called to tell me that a blood test had confirmed her doctor’s suspicion: She had hypothyroidism, meaning her body no longer made enough thyroid hormone.

Her metabolism had slowed to a snail’s pace, and the fat was accumulating. This was her body rebelling. When Jill asked for my advice, I told her to do two things: To schedule a second test for two weeks later, and to stop all running until then.

Running with Everything in You

I’m not here to pick on women or make fun of them. There are men out there who do the same thing, thinking cardio will wipe away the effects of their regular weekend beer binges. It’s more of a problem with women, though, and I’m targeting them for three very good reasons:

1.  They’re often intensely recruited for fund-raisers like Team-In-Training, lured by the promises of slim, trim bodies and good health resulting from the months of cardio training leading to marathons—in addition to doing something for charity.

2.  Some physique coaches prescribe 20-plus hours per week of pre-contest cardio for women, which essentially amounts to a part-time job.

3.  Steady-state activities like this devastate the female metabolism. This happens with men, too, but in different ways.

One of the things that the fitness industry is doing wrong is over-prescribing cardio. I’m not talking about walking here, nor am I referring to appropriate HIIT cardio. This is about running, cycling, stair-climbing, or elliptical cardio done for hours at or above 65 percent of your max heart rate. The anaerobic threshold factors into this, but I’m painting gym cardio in very broad strokes here so everyone will understand what I mean.

Science Wants You to Stop Running

Studies—both clinical and observational—make a compelling case that too much cardio can impair the production of the thyroid hormone T3, its effectiveness and metabolism[1-11], particularly when accompanied by caloric restriction, an all too common practice. This is why many first or second-time figure and bikini competitors explode in weight when they return to their normal diets, and it’s why the Jills of the world can run for hours every week with negative results.
T3 is the body’s preeminent regulator of metabolism, by the way it throttles the efficiency of cells[12-19]. It also acts in various ways to increase heat production[20-21]. As I pointed out in previous articles, this is one reason why using static equations to perform calories-in, calories-out weight loss calculations doesn’t work.

When T3 levels are normal, the body burns enough energy to stay warm, and muscles function at moderate efficiency. When there’s too much thyroid hormone (hyperthyroidism), the body goes into a state where weight gain is almost impossible. Too little T3 (hypothyroidism), and the body accumulates body fat with ease, almost regardless of physical activity level. Women inadvertently put themselves into a hypothyroid condition when they perform so much steady-state cardio.

In the quest to lose body fat, T3 levels can offer both success and miserable failure because of the way it influences other fat-regulating hormones[22-31]. Women additionally get all the other negative effects of this, which I’ll cover below. Don’t be surprised here. This is a simple, sensible adaptation of a body that’s equipped to bear the full brunt of reproduction.

We Were Not Designed For This

Think about it this way: Your body is a responsive, adaptive machine that has evolved for survival. If you’re running on a regular basis, your body senses this excessive energy expenditure, and adjusts to compensate. Remember, no matter which way we hope the body works, its endgame is always survival. If you waste energy running, your body will react by slowing your metabolism to conserve energy. Decreasing energy output is biologically savvy for your body. Your body wants to survive longer while you do what it views as a stressful, useless activity. Decreasing T3 production increases efficiency and adjusts your metabolism to preserve energy immediately.

Nothing exemplifies this increasing efficiency better than the way the body starts burning fuel. Training consistently at 65 percent or more of your max heart rate adapts your body to save as much body fat as possible. After regular training, fat cells stop releasing fat the way they once did during moderate-intensity activities[32-33]. Energy from body fat stores also decreases by 30 percent[34-35]. To this end, your body sets into motion a series of reactions that make it difficult for muscle to burn fat at all[36-41]. Instead of burning body fat, your body takes extraordinary measures to retain it.

Still believe cardio is the fast track to fat loss?

That’s not all. You can still lose muscle mass. Too much steady-state cardio actually triggers the loss of muscle[42-45]. This seems to be a twofold mechanism, with heightened and sustained cortisol levels triggering muscle loss[46-56], which upregulates myostatin, a potent destroyer of muscle tissue[57]. Say goodbye to bone density, too, because it declines with that decreasing muscle mass and strength[58-64].

And long term health? Out the window, as well. Your percentage of muscle mass is an independent indicator of health[65]. You’ll lose muscle, lose bone, and lose health. Awesome, right?

When sewn together, these phenomena coordinate a symphony of fat gain for most female competitors after figure contests. After a month—or three—of 20-plus hours of cardio per week, fat burning hits astonishing lows, and fat cells await an onslaught of calories to store[66-72]. The worst thing imaginable in this state would be to eat whatever you wanted, whenever you wanted. The combination of elevated insulin and cortisol would make you fat, and it would also create new fat cells so you could become even fatter[73-80].

Seriously, Lets Cut Out the Long Distance Cardio

I won’t name names, but I’ve seen amazing displays of gluttony from some small, trim women. Entire pizzas disappear, leaving only the flotsam of toppings that fell during the feeding frenzy. Appetizers, meals, cocktails and desserts—4000 calories worth—vanish at the Cheesecake Factory. There are no leftovers, and there are no crumbs. Some women catch this in time and stop the devastation, but others quickly swell, realizing that this supposed off-season look has become their every-season look.

And guess what they do to fix it? Double sessions of cardio.

The right way to train

This “cardio craze” is a form of insanity. There are better ways to lose fat, and there are better ways to look good. Your beach body is not at the end of a marathon, and you won’t find it on a treadmill. In fact, it’s quite the opposite if you’re using steady-state cardio to get there. The show may be over, and the finish line crossed, but the damage to your metabolism has just begun.

Don’t want to stop running? It's OK. Just keep in mind though that the fat won’t come off your hips, thighs, etc. following that approach. You’re keeping it there.

And as for Jill, my friend whose dilemma sparked this article? She took my suggestion and cut out the cardio. Two weeks later, her T3 count was normal ;).

DH Kiefer
After graduating magna cum laude in three years with degrees in mathematics and physics, then becoming a Ph.D. candidate in physics at the University of Florida in just one year, Kiefer knows the value of academic research. These credentials, however, aren’t some fitness industry gimmick designed to hook you in. Kiefer’s been researching, testing, and verifying what hard science proves as fact for over two decades. And as his clients and readers of The Carb Nite Solution and Carb Back-Loading will attest, his results are the absolute best in the business.

References

1.     Baylor LS, Hackney AC. Resting thyroid and leptin hormone changes in women following intense, prolonged exercise training. Eur J Appl Physiol. 2003 Jan;88(4-5):480-4.

2.     Boyden TW, Pamenter RW, Rotkis TC, Stanforth P, Wilmore JH. Thyroidal changes associated with endurance training in women. Med Sci Sports Exerc. 1984 Jun;16(3):243-6.

3.     Wesche MF, Wiersinga WM. Relation between lean body mass and thyroid volume in competition rowers before and during intensive physical training. Horm Metab Res. 2001 Jul;33(7):423-7.

4.     Tremblay A, Poehlman ET, Despres JP, Theriault G, Danforth E, Bouchard C. Endurance training with constant energy intake in identical twins: changes over time in energy expenditure and related hormones. Metabolism. 1997 May;46(5):499-503.

5.     Rone JK, Dons RF, Reed HL. The effect of endurance training on serum triiodothyronine kinetics in man: physical conditioning marked by enhanced thyroid hormone metabolism. Clin Endocrinol (Oxf). 1992 Oct;37(4):325-30.

6.     Loucks AB, Callister R. Induction and prevention of low-T3 syndrome in exercising women. Am J Physiol. 1993 May;264(5 Pt 2):R924-30.

7.     Loucks AB, Heath EM. Induction of low-T3 syndrome in exercising women occurs at a threshold of energy availability. Am J Physiol. 1994 Mar;266(3 Pt 2):R817-23.

8.     Rosolowska-Huszcz D. The effect of exercise training intensity on thyroid activity at rest. J Physiol Pharmacol. 1998 Sep;49(3):457-66.

9.     Wirth A, Holm G, Lindstedt G, Lundberg PA, Bjorntorp P. Thyroid hormones and lipolysis in physically trained rats. Metabolism. 1981 Mar;30(3):237-41.

10.  Opstad PK, Falch D, Oktedalen O, Fonnum F, Wergeland R. The thyroid function in young men during prolonged exercise and the effect of energy and sleep deprivation. Clin Endocrinol (Oxf). 1984 Jun;20(6):657-69.

11.  Hohtari H, Pakarinen A, Kauppila A. Serum concentrations of thyrotropin, thyroxine, triiodothyronine and thyroxine binding globulin in female endurance runners and joggers. Acta Endocrinol (Copenh). 1987 Jan;114(1):41-6.

12.  Lanni A, Moreno M, Lombardi A, Goglia F. Thyroid hormone and uncoupling proteins. FEBS Lett. 2003 May 22;543(1-3):5-10. Review.

13.  Leijendekker WJ, van Hardeveld C, Elzinga G. Heat production during contraction in skeletal muscle of hypothyroid mice. Am J Physiol. 1987 Aug;253(2 Pt 1):E214-20.

14.  Silva JE. Thyroid hormone control of thermogenesis and energy balance. Thyroid. 1995 Dec;5(6):481-92. Review.

15.  Argyropoulos G, Harper ME. Uncoupling proteins and thermoregulation. J Appl Physiol. 2002 May;92(5):2187-98. Review.

16.  Rolfe DF, Brown GC. Cellular energy utilization and molecular origin of standard metabolic rate in mammals. Physiol Rev. 1997 Jul;77(3):731-58. Review.

17.  Danforth E Jr, Burger A. The role of thyroid hormones in the control of energy expenditure. Clin Endocrinol Metab. 1984 Nov;13(3):581-95. Review.

18.  Schrauwen P, Hesselink M. UCP2 and UCP3 in muscle controlling body metabolism. J Exp Biol. 2002 Aug;205(Pt 15):2275-85. Review.

19.  Silva JE. The multiple contributions of thyroid hormone to heat production. J Clin Invest. 2001 Jul;108(1):35-7.

20.  Goglia F, Silvestri E, Lanni A. Thyroid hormones and mitochondria. Biosci Rep. 2002 Feb;22(1):17-32. Review.

21.  Goglia F, Moreno M, Lanni A. Action of thyroid hormones at the cellular level: the mitochondrial target. FEBS Lett. 1999 Jun 11;452(3):115-20. Review.

22.  Ribeiro MO, Carvalho SD, Schultz JJ, Chiellini G, Scanlan TS, Bianco AC, Brent GA. Thyroid hormone–sympathetic interaction and adaptive thermogenesis are thyroid hormone receptor isoform–specific. J Clin Invest. 2001 Jul;108(1):97-105.

23.  Beylot M, Riou JP, Bienvenu F, Mornex R. Increased ketonaemia in hyperthyroidism. Evidence for a beta-adrenergic mechanism. Diabetologia. 1980;19(6):505-10.

24.  Ostman J, Arner P, Bolinder J, Engfeldt P, Wennlund A. Regulation of lipolysis in hyperthyroidism. Int J Obes. 1981;5(6):665-70.

25.  Collins S, Cao W, Daniel KW, Dixon TM, Medvedev AV, Onuma H, Surwit R. Adrenoceptors, uncoupling proteins, and energy expenditure. Exp Biol Med (Maywood). 2001 Dec;226(11):982-90.

26.  Williams LT, Lefkowitz RJ, Watanabe AM, Hathaway DR, Besch HR Jr. Thyroid hormone regulation of beta-adrenergic receptor number. J Biol Chem. 1977 Apr 25;252(8):2787-9.

27.  Martin WH 3rd. Triiodothyronine, beta-adrenergic receptors, agonist responses, and exercise capacity. Ann Thorac Surg. 1993 Jul;56(1 Suppl):S24-34.

28.  Tsujimoto G, Hashimoto K, Hoffman BB. Effects of thyroid hormone on beta-adrenergic responsiveness of aging cardiovascular systems. Am J Physiol. 1987 Mar;252(3 Pt 2):H513-20.

29.  Richelsen B, Sorensen NS. Alpha 2- and beta-adrenergic receptor binding and action in gluteal adipocytes from patients with hypothyroidism and hyperthyroidism. Metabolism. 1987 Nov;36(11):1031-9.

30.  Wang JL, Chinookoswong N, Yin S, Shi ZQ. Calorigenic actions of leptin are additive to, but not dependent on, those of thyroid hormones. Am J Physiol Endocrinol Metab. 2000 Dec;279(6):E1278-85.

31.  Seidel A, Heldmaier G. Thyroid hormones affect the physiological availability of nonshivering thermogenesis. Pflugers Arch. 1982 May;393(3):283-5.

32.  Jones NL, Heigenhauser GJ, Kuksis A, Matsos CG, Sutton JR, Toews CJ. Fat metabolism in heavy exercise. Clin Sci (Lond). 1980 Dec;59(6):469-78.

33.  Romijn JA, Coyle EF, Sidossis LS, Zhang XJ, Wolfe RR. Relationship between fatty acid delivery and fatty acid oxidation during strenuous exercise. J Appl Physiol. 1995 Dec;79(6):1939-45.

34.  Romijn JA, Coyle EF, Sidossis LS, Gastaldelli A, Horowitz JF, Endert E, Wolfe RR. Regulation of endogenous fat and carbohydrate metabolism in relation to exercise intensity and duration. Am J Physiol Endocrinol Metab. 1993;265:E380-E391.

35.  Martin WH 3rd, Dalsky GP, Hurley BF, Matthews DE, Bier DM, Hagberg JM, Rogers MA, King DS, Holloszy JO.  Effect of endurance training on plasma free fatty acid turnover and oxidation during exercise. Am J Physiol. 1993;265:E708–14.

36.  Elayan IM, Winder WW. Effect of glucose infusion on muscle malonyl-CoA during exercise. J Appl Physiol. 1991 Apr;70(4):1495-9.

37.  Saddik M, Gamble J, Witters LA, Lopaschuk GD. Acetyl-CoA carboxylase regulation of fatty acid oxidation in the heart. J Biol Chem. 1993 Dec 5;268(34):25836-45.

38.  McGarry JD, Mannaerts GP, Foster DW. A possible role for malonyl-CoA in the regulation of hepatic fatty acid oxidation and ketogenesis. J Clin Invest. 1977 Jul;60(1):265-70.

39.  Robinson IN, Zammit VA. Sensitivity of carnitine acyltransferase I to malonly-CoA inhibition in isolated rat liver mitochondria is quantitatively related to hepatic malonyl-CoA concentration in vivo. Biochem J. 1982 Jul 15;206(1):177-9.

40.  McGarry JD, Mills SE, Long CS, Foster DW. Observations on the affinity for carnitine, and malonyl-CoA sensitivity, of carnitine palmitoyltransferase I in animal and human tissues. Demonstration of the presence of malonyl-CoA in non-hepatic tissues of the rat. Biochem J. 1983 Jul 15;214(1):21-8.

41.  Sidossis LS, Gastaldelli A, Klein S, Wolfe RR. Regulation of plasma fatty acid oxidation during low- and high-intensity exercise. Am J Physiol. 1997;272:E1065–70.

42.  Mertens DJ, Rhind S, Berkhoff F, Dugmore D, Shek PN, Shephard RJ. Nutritional, immunologic and psychological responses to a 7250 km run. J Sports Med Phys Fitness. 1996 Jun;36(2):132-8.

43.  Wesche MF, Wiersinga WM. Relation between lean body mass and thyroid volume in competition rowers before and during intensive physical training. Horm Metab Res. 2001 Jul;33(7):423-7.

44.  Eliakim A, Brasel JA, Mohan S, Barstow TJ, Berman N, Cooper DM. Physical fitness, endurance training, and the growth hormone-insulin-like growth factor I system in adolescent females. J Clin Endocrinol Metab. 1996 Nov;81(11):3986-92.

45.  Bisschop PH, Sauerwein HP, Endert E, Romijn JA. Isocaloric carbohydrate deprivation induces protein catabolism despite a low T3-syndrome in healthy men. Clin Endocrinol (Oxf). 2001 Jan;54(1):75-80.

46.  Essig DA, Alderson NL, Ferguson MA, Bartoli WP, Durstine JL. Delayed effects of exercise on the plasma leptin concentration. Metabolism. 2000 Mar;49(3):395-9.

47.  Kanaley JA, Weltman JY, Pieper KS, Weltman A, Hartman ML. Cortisol and growth hormone responses to exercise at different times of day. J Clin Endocrinol Metab. 2001 Jun;86(6):2881-9.

48.  Duclos M, Gouarne C, Bonnemaison D. Acute and chronic effects of exercise on tissue sensitivity to glucocorticoids. J Appl Physiol. 2003 Mar;94(3):869-75.

49.  Duclos M, Corcuff JB, Pehourcq F, Tabarin A. Decreased pituitary sensitivity to glucocorticoids in endurance-trained men. Eur J Endocrinol. 2001 Apr;144(4):363-8.

50.  Heitkamp HC, Schulz H, Rocker K, Dickhuth HH. Endurance training in females: changes in beta-endorphin and ACTH. Int J Sports Med. 1998 May;19(4):260-4.

51.  Duclos M, Corcuff JB, Arsac L, Moreau-Gaudry F, Rashedi M, Roger P, Tabarin A, Manier G. Corticotroph axis sensitivity after exercise in endurance-trained athletes. Clin Endocrinol (Oxf). 1998 Apr;48(4):493-501.

52.  Tyndall GL, Kobe RW, Houmard JA. Cortisol, testosterone, and insulin action during intense swimming training in humans. Eur J Appl Physiol Occup Physiol. 1996;73(1-2):61-5.

53.  Vasankari TJ, Kujala UM, Heinonen OJ, Huhtaniemi IT. Effects of endurance training on hormonal responses to prolonged physical exercise in males. Acta Endocrinol (Copenh). 1993 Aug;129(2):109-13.

54.  Hoogeveen AR, Zonderland ML. Relationships between testosterone, cortisol and performance in professional cyclists. Int J Sports Med. 1996 Aug;17(6):423-8.

55.  Seidman DS, Dolev E, Deuster PA, Burstein R, Arnon R, Epstein Y. Androgenic response to long-term physical training in male subjects. Int J Sports Med. 1990 Dec;11(6):421-4.

56.  Duclos, M, Corcuff JB, Rashedi M, Fougere V, and Manier G. Trained versus untrained: different hypothalamo-pituitary adrenal axis responses to exercise recovery. Eur J Appl Physiol 75: 343-350, 1997.

57.  Ma K, Mallidis C, Bhasin S, Mahabadi V, Artaza J, Gonzalez-Cadavid N, Arias J, Salehian B. Glucocorticoid-induced skeletal muscle atrophy is associated with upregulation of myostatin gene expression. Am J Physiol Endocrinol Metab. 2003 Aug;285(2):E363-71.

58.  Cvijetić S, Grazio S, Gomzi M, Krapac L, Nemcić T, Uremović M, Bobić J. Muscle strength and bone density in patients with different rheumatic conditions: cross-sectional study. Croat Med J. 2011 Apr 15;52(2):164-70.

59.  Dixon WG, Lunt M, Pye SR, Reeve J, Felsenberg D, Silman AJ, O’Neill TW; European Prospective Osteoporosis Study Group. Low grip strength is associated with bone mineral density and vertebral fracture in women. Rheumatology (Oxford). 2005 May;44(5):642-6.

60.  Lekamwasam S, Weerarathna T, Rodrigo M, Arachchi WK, Munidasa D. Association between bone mineral density, lean mass, and fat mass among healthy middle-aged premenopausal women: a cross-sectional study in southern Sri Lanka. J Bone Miner Metab. 2009;27(1):83-8.

61.  Li S, Wagner R, Holm K, Lehotsky J, Zinaman MJ. Relationship between soft tissue body composition and bone mass in perimenopausal women. Maturitas. 2004 Feb 20;47(2):99-105.

62.  Salamone LM, Glynn N, Black D, Epstein RS, Palermo L, Meilahn E, Kuller LH, Cauley JA. Body composition and bone mineral density in premenopausal and early perimenopausal women. J Bone Miner Res. 1995 Nov;10(11):1762-8.

63.  Winters KM, Snow CM. Body composition predicts bone mineral density and balance in premenopausal women. J Womens Health Gend Based Med. 2000 Oct;9(8):865-72.

64.  Witzke KA, Snow CM. Lean body mass and leg power best predict bone mineral density in adolescent girls. Med Sci Sports Exerc. 1999 Nov;31(11):1558-63.

65.  Allison DB, Zannolli R, Faith MS, Heo M, Pietrobelli A, VanItallie TB, Pi-Sunyer FX, Heymsfield SB. Weight loss increases and fat loss decreases all-cause mortality rate: results from two independent cohort studies. Int J Obes Relat Metab Disord. 1999 Jun;23(6):603-11.

66.  Savard R, Despres JP, Marcotte M, Bouchard C. Endurance training and glucose conversion into triglycerides in human fat cells. J Appl Physiol. 1985 Jan;58(1):230-5.

67.  Viru A, Toode K, Eller A. Adipocyte responses to adrenaline and insulin in active and former sportsmen. Eur J Appl Physiol Occup Physiol. 1992;64(4):345-9.

68.  Hickner RC, Racette SB, Binder EF, Fisher JS, Kohrt WM. Effects of 10 days of endurance exercise training on the suppression of whole body and regional lipolysis by insulin. J Clin Endocrinol Metab. 2000 Apr;85(4):1498-504.

69.  Gommers A, Dehez-Delhaye M, Caucheteux D. Prolonged effects of training on adipose tissue glucose metabolism and insulin responsiveness in adult rats (author’s transl) Diabete Metab. 1981 Jun;7(2):121-6.

70.  Perreault L, Lavely JM, Kittelson JM, Horton TJ. Gender differences in lipoprotein lipase activity after acute exercise. Obes Res. 2004 Feb;12(2):241-9.

71.  Taskinen MR, Nikkila EA. Effect of acute vigorous exercise on lipoprotein lipase activity of adipose tissue and skeletal muscle in physically active men. Artery. 1980;6(6):471-83.

72.  Farese RV Jr, Yost TJ, Eckel RH. Tissue-specific regulation of lipoprotein lipase activity by insulin/glucose in normal-weight humans. Metabolism. 1991 Feb;40(2):214-6.

73.  Gregoire F, Genart C, Hauser N, Remacle C. Glucocorticoids induce a drastic inhibition of proliferation and stimulate differentiation of adult rat fat cell precursors. Exp Cell Res. 1991 Oct;196(2):270-8.

74.  Xu XF, Bjorntorp P. Effects of dexamethasone on multiplication and differentiation of rat adipose precursor cells. Exp Cell Res. 1990 Aug;189(2):247-52.

75.  Hentges EJ, Hausman GJ. Primary cultures of stromal-vascular cells from pig adipose tissue: the influence of glucocorticoids and insulin as inducers of adipocyte differentiation. Domest Anim Endocrinol. 1989 Jul;6(3):275-85.

76.  Hauner H, Entenmann G, Wabitsch M, Gaillard D, Ailhaud G, Negrel R, Pfeiffer EF. Promoting effect of glucocorticoids on the differentiation of human adipocyte precursor cells cultured in a chemically defined medium. J Clin Invest. 1989 Nov;84(5):1663-70.

77.  Hauner H, Schmid P, Pfeiffer EF. Glucocorticoids and insulin promote the differentiation of human adipocyte precursor cells into fat cells. J Clin Endocrinol Metab. 1987 Apr;64(4):832-5.

78.  Ramsay TG, White ME, Wolverton CK. Glucocorticoids and the differentiation of porcine preadipocytes. J Anim Sci. 1989 Sep;67(9):2222-9.

79.  Bujalska IJ, Kumar S, Hewison M, Stewart PM. Differentiation of adipose stromal cells: the roles of glucocorticoids and 11beta-hydroxysteroid dehydrogenase. Endocrinology. 1999 Jul;140(7):3188-96.

80.  Nougues J, Reyne Y, Barenton B, Chery T, Garandel V, Soriano J. Differentiation of adipocyte precursors in a serum-free medium is influenced by glucocorticoids and endogenously produced insulin-like growth factor-I. Int J Obes Relat Metab Disord. 1993 Mar;17(3):159-67.




Tweet This

Girl Power: Why Lifting Heavier Can Be a Life Changer

Tweet

I want to give you real, relatable rationale as to why women should be training big movements with relatively heavy weights.

Reason 1: It's Empowering.
There is nothing that can compare to deadlifting 200-pounds, bench pressing your bodyweight, or reaching any other strength goal you set for yourself. Not only will you feel stronger in the gym, you'll be stronger in every other aspect of your life. It may be hard to imagine how a heavy squat can translate over to a happier relationship or better performance at work, but I've seen it happen time and time again. There is something transformative about being able to do something that seemed impossible a few short weeks before. And once you realize achieving those milestones is possible, everything else in life seems possible. And I guarantee you that belief is much more appealing to women than having to train with pink dumbbells in the "Women's Only" section of their gym because they're afraid of getting stared at on the main floor.

Reason 2: It Will Improve Body Composition.
Katlyn was probably the best female lifter (and maybe the best lifter, period) I have ever had the pleasure of training. She was also the sweetest person you could ever meet. She would bop into the gym, a huge smile on her face, and ask me about my weekend. But when it was time to lift, she would get pretty darn intense. One second she'd be asking me if I'd seen such-and-such a movie, and the next second, she'd step up to the bar and totally transform. But once the barbell hit the ground she would go back to being all sunshine and rainbows. It was something to watch.

In our time together Katlyn worked up to a 296-pound deadlift and set a PR of 23 pull-ups. When she would bang out reps, jaws would drop to the floor - not only because she had the strength to move that type of weight, but because she had the toned, lean look female clients were sweating their butts off on the treadmill trying to attain.

The fact Katlyn took her strength training seriously and also had the best body composition of any female client I have trained is not a coincidence. In fact, I would say there is a direct correlation between the number of pounds my clients can squat, pull, and press, and what they look like in a strapless dress. And since so many female clients are training to improve body composition, I always like to mention that.

Reason 3: It's Not the Same Old, Same Old
It stands to reason that if you do the same thing over and over (and over) again, you will probably get very, very good at that thing. And that's great if you want to become a chess master or play the clarinet. When it comes to fitness, repeating the same exercise protocols ad nauseam also leads to getting very efficient at those programs. Unfortunately, exercise efficiency is the enemy of adaptation and body composition improvements. To put it simply, if you get very comfortable with your workout routine, you are not challenging your body to produce change. There is a famous saying that the definition of the term "crazy" is doing the same thing over and over again and expecting different results. So if you've been banging out 20 reps of incline press with 7-pound dumbbells for the past six months, chances are your body's not responding to that anymore.

Plus, lifting heavy and challenging yourself every time you step in the gym will get you excited (and maybe even a little nervous) for your training sessions. And, truthfully, when was the last time you were really psyched to work out?

Reason 4: You'll Be Part of a Community.
When anyone in our gym goes for a personal best lift (meaning they are trying to lift a weight that is greater than they've ever lifted before) something amazing happens. Rather spontaneously, a group will form around that person, trying to psych her up for the lift. Words of encouragement will be shouted. Cheers will be heard. It's as if everyone in the gym is part of the effort. And whether she hits the deadlift or locks out the bench press is almost irrelevant. She will be applauded for the effort and congratulated for the attempt. Discussions will occur as to what she did right, or how to nail it next time. Maybe someone grabbed a quick video on their iPhone so she can now relive and celebrate her success. Interestingly enough, when I've gone to other gyms, I've seen this same type of camaraderie.

Now, I know what you're thinking. You probably don't want all eyes on you when working out. You might prefer to anonymously sweat out your 40 minutes on the elliptical trainer while reading about the latest escapades of your favorite reality television stars. But I cannot encourage you enough to break out of your fortress of solitude and become part of your gym's community. Having people root for you and celebrate with you when you've achieved something you've never done before, something that may have not even seemed possible a few short weeks before, is not only awesome, it's addictive.

Reason 5: You Can Use It.
Whether you want to pick your nieces up off the floor or carry a couple of bottles of apple juice home from the store, getting stronger will help you in more ways than you realize throughout your day. Obviously women hold big positions of power in today's society, and yet on my morning commute I see women who can't generate enough power to hoist their computer bags up to their shoulders.

Last time I checked, no one really had to go to train at the gym to pick up a small stack of paper, yet if that's the amount of weight you are training with, that's about all you'll be able to do.

Reason 6: It's Healthy.
The loss of bone density, specifically in post-menopausal women, is a growing concern in the population. By lifting heavier loads you can reduce this risk and make it less likely that you'll crack in half when you reach your "golden years." Also, the ability to generate power and strength (and this is true for men and women) are the fitness qualities that decline most rapidly when we age. This is why we see more 55-year-olds competing in the marathon and not at a local power lifting meet. So think of adding serious strength training now - kind of like you think of your 401K. Even if you don't plan on using it for the next 20 years, you'll be glad it's there down the road.

So break out of your comfort zone and discover the true benefits of lifting heavier weight and you'll see body transforms. And, I promise, you won't end up looking anything like me :)

This guest post was written by Dan Trink, CSCS and Director of Personal Training Operations at Peak Performance in NYC. To learn more about Dan, follow him on Facebook and Twitter, or at his website www.trinkfitness.com.

Tyron

PS. On a side note, we have a Pre-Warm-up Board installed at the gym so we encourage all members to arrive 10-15 minutes early to go through the key pre-warm-up items listed on it. Here's what it is:

CrossFit Pre-Warm-up
Foam Roll Tight Spots: Quads, Hip Flexors, Glutes, Calves, Lats, etc.
10 Shoulder Pass-through
60 sec Couch Stretch with 10 Mobilizations
25 Squats
3 min Skip, Run or Row
25 KB Swings
10 Pull-ups
10 Push-ups
Work On Weaknesses

PPS. Just a friendly reminder about our 10 Burpee Penalty at the gym for those that don't know. For each piece of equipment you leave out, there's a 10 burpee penalty next time you come to the gym :)  It's all in good fun. We just want to prevent our coaches from having to clean up after everyone. You all rock! Thanks for being the greatest group to coach!




Tweet This

How to Counter The Many Negatives of Aerobic Training

Tweet

Aerobic training has many negative health effects, and being as more than 45,000 people ran the 2011 New York City Marathon, this topic is more important than ever. Aerobic training stresses the adrenals, chronically raises cortisol, may lower testosterone, may hinder reproduction, can shrink reproductive organs, causes oxidative stress, and results in persistent inflammation. It lowers peak power output, makes you slower, and leads to a catabolic state in the body if you perform it regularly without any resistance training.

Research scientists and athletic coaches have begun to express concern about the negative health effects of aerobic training, particularly for aerobic endurance athletes who put themselves under high daily physiological stress for prolonged periods. In fact, they’ve started to look for strategies to minimize the many negatives of aerobic training, and luckily there are some things that work! Adding strength training to an aerobic program, practicing martial arts, and supplementing with specific antioxidants and nutrients can actually do wonders to counteract the negatives of aerobic exercise.
Of course, it would be easier to just stop the aerobic exercise and substitute it with strength and anaerobic system training for better results and fewer negative health effects. But, since doctors and health professionals continue to recommend aerobic exercise, and even Apolo Ohno has taken up endurance running and competed in the New York City Marathon, this trend towards aerobic exercise doesn’t seem to be diminishing. And there are still some common misconceptions about aerobic exercise about why aerobic training is bad.

In this article, I will address the confusing aspects of the negatives of aerobic training, and provide some simple things aerobic endurance trainees can do to minimize the negative health effects and improve performance. Coaches and trainers who work with elite aerobic athletes should take note because these are research-proven ways to better performance and wellness for your athletes.

Short Review of the Bad News About Aerobic Training
Long-term aerobic training, both at an elite level and at a recreational intensity, has been shown to lead to chronic inflammation and elevated cortisol. Chronic inflammation is bad because it results in premature aging of tissues and has been linked to heart disease, diabetes, and cancer. For the recreational population that may perform anywhere from 20 to 45 minutes of aerobic training a few days a week, aerobic training typically leads to elevated cortisol, lower androgen hormones, increased inflammation, and does little to help with fat or weight loss. “The effect of regular aerobic exercise on body fat is negligible,” writes researcher Stephen H. Boutcher in his article “High-Intensity Intermittent Exercise and Fat Loss.” ?

Aerobic training doesn’t help with fat loss because it creates a hormonal environment that degrades muscle, spikes cortisol, and even though you’re burning calories, the deficit is rarely enough to offset the catabolic hormonal environment. Plus, if you’re doing aerobic training on exercise machines, you may suffer from lower insulin sensitivity from exposure to “dirty electricity” or the electromagnetic frequency bands that are generated by cardio machines and other forms of electrical power.

The situation is slightly different for elite or long distance aerobic endurance athletes. Research shows they suffer from an even greater catabolic hormonal state with significantly high cortisol levels from the intense physiological stress of training. They also have lower testosterone and androgens. High cortisol and exposure to inflammatory biomarkers has researchers and coaches concerned about the residual health effects for endurance athletes and they have started to look for ways to counter the negatives.

Body Fat and Elite Aerobic Athletes
Elite aerobic athletes do tend to have lower body fat compared to the rest of the population, but research shows that anaerobic athletes such as sprinters have even lower body fat than long distance runners. This is because they have more muscle, which helps burn fat, and because they do sprints that also burn fat. Also, studies show endurance athletes who perform strength training as part of the program have lower body fat than those who don’t. 

Benefits of Aerobic Training for Sedentary People
There are some benefits of aerobic exercise for sedentary people and specific populations, but there are also negatives that can be avoided if you just choose a different mode of exercise—strength and anaerobic system training. The key here is that it is better to do aerobic training than to do absolutely nothing and be sedentary. So, if you only have two options, of being sedentary and not moving, or doing 30 minutes of aerobic training, by all means, do the aerobic training. But, you’ll get better results if you do strength training instead, or in addition to the aerobic training.

To review, the bad news about aerobic training is that it doesn’t help the everyday person lose fat; it elevates cortisol, lowers androgens, degrades muscle, lowers power, and increases inflammation if done for a prolonged period. Now for the good news!

Take Antioxidants to Reduce Inflammation and Oxidative Stress
Get as many antioxidants in your diet as possible to fight inflammation and oxidative stress. Oxidative stress occurs when the body produces free radicals in response to the oxygen-rich environment created by increased respiration that goes with aerobic training. The free radicals need to be neutralized; otherwise, they damage cells and cause premature aging, which leads to chronic inflammation. Chronic inflammation has been termed “the silent killer” and is caused by a lot of “unhealthy” behaviors, such as having a diet high in trans fats or gluten, and being sedentary. People are often surprised to hear that a “healthy” behavior such as aerobic exercise can cause chronic inflammation, but it does.

Research performed on rats has shown that the negative effects of intense aerobic training can be mitigated by taking antioxidants, specifically vitamin E, selenium, and zinc. A study in the journal Free Radical Research found that vitamin E has a protective effect against oxidative stress in rats that performed intense aerobic swimming. In contrast, the control group rats that did not receive the vitamin E supplement had decreased size of the reproductive organs (testes and accessory sex organs), lower testosterone and related androgen markers, and inflammation and dysfunction of the reproductive organs. Researchers suggest that vitamin E elevates scavenger enzyme activity and gets rid of free radicals, effectively detoxifying the reproductive system of oxidative chemicals.

Take note that the rats performed intense amounts of aerobic swimming—three hours a day, five days a week for four weeks, which is in line with what someone might perform running-wise to prepare for a marathon. And, elite aerobic athletes do this quantity of exercise regularly for many years.

A second study using zinc and selenium for the antioxidants supports these findings. The same intense aerobic exercise protocol was used and the rats who received no supplement had the same harmful effects on their reproductive systems, and they were also found to be significantly less fertile due to the low testosterone and fewer fertile sperm. Their cortisol was also very high. Researchers suggest the antioxidants had a strong stimulatory effect on production of sperm and the androgen hormones, supporting fertility. Zinc and selenium also fought the free radical attack, effectively lowering the inflammatory response.

A 2001 Sports Medicine review of antioxidant use to counter oxidative stress from aerobic training supports the use of antioxidants, of which vitamin E is most commonly tested and most effective. Antioxidant mixtures of beta carotene and the vitamins C and E also appear to be protective. Results from human studies haven’t been as conclusive as those performed on rats because with animal studies the experiment can be more closely controlled and the animals are forced to complete very intense long duration  aerobic exercise, whereas with humans there are more unknown factors. Also, diet, genetic disposition, and exercise history can result in a significant variation in the inflammatory effects of aerobic exercise.

For aerobic athletes, the potential for protection from antioxidant supplementation is “tremendous” and “consumption of a diet rich in different antioxidants is a prudent course of action,” conclude researchers from the 2001 Sports Medicine review. In addition to the nutrients already mentioned, it is possible magnesium, probiotics, gotu kola, and vitamin D will also help counter oxidative stress from training. Eating fruits high in antioxidants, such as berries, particularly raspberries, strawberries, and tart cherries is recommended because they have been shown to have anti-inflammatory effects in athletes.

Perform Strength Training
Everybody should perform strength training. Naturally, the type and protocol of the training will vary according to goals, age, and health complications, but everyone will benefit from exercises that improve strength, especially endurance athletes and aerobic devotees. Researchers have suggested that because strength training lowers chronic inflammation and provides protection against oxidative stress, it is an ideal solution for coaches and athletes who are concerned about free radical-mediated damage from exercise. This means that simply adding strength training to an aerobic exercise program may counter many of the negatives of aerobics

One recent study in the Journal of Strength and Conditioning Research compared the inflammatory response of two resistance training protocols after six weeks. Both a hypertrophy and strength protocol were effective at reducing oxidative stress and lowering inflammatory biomarkers over pre-training levels. Researchers found that both protocols resulted in lower inflammation, and they suggest that endurance athletes perform resistance training rather than supplement with antioxidants to decrease oxidative stress.

Aerobic Athletes Will Lose Body Fat & Improve Performance by Strength Training
Another new study in the Scandinavian Journal of Medicine and Science in Sports shows how adding a strength protocol into aerobic training programs will improve performance and lead to a better body composition for elite aerobic athletes. The study didn’t directly test for oxidative stress or cortisol but it measured body fat, muscle cross sectional area, and short- and long-term endurance capacity in two groups of elite aerobic cyclists: an aerobic-only group that just performed their normal training and an aerobic/strength group that performed normal training with a strength program for 16 weeks.

Researchers found that the aerobic/strength group decreased body fat significantly by an average of two percent from 12 to 10 percent, while body fat remained unchanged in the aerobic-only group.

Other significant improvements in the aerobics/strength group that weren’t seen in the aerobics-only group were increased quadriceps strengths by 12 percent, better performance in a 45-minute time trial, and slightly better performance in a 5-minute time trial. There were no negative effects of strength training for the aerobic/strength group, such as increased body weight or hypertrophy—both common concerns because elite aerobic athletes mistakenly believe that gaining strength will make them slower.

A study published in the Journal of Strength and Conditioning Research provides potent evidence for never doing aerobic training without also performing strength training. The article is a review of all previously published evidence on the effects of combining aerobic and strength training. The study found that adding strength training to aerobic programs increased performance, strength, and power.

In contrast, the main negative was that aerobic training alone compromised power output. It’s especially critical that athletes in sports such as basketball, football, tennis, ice hockey, and volleyball be able to produce peak power, meaning they should never do aerobic training. Rather, interval sprints are ideal for conditioning and will produce less oxidative stress and a better hormonal response. Sprints have been shown to raise growth hormone, insulin-like growth factor-1, and produce a favorable testosterone to cortisol ratio.

Obviously, if you plan to run 26 miles in a marathon, sprint training alone will not be effective. Instead, add strength training to your regular aerobic training and you’ll have a better hormonal response, and less body fat, according to the Journal of Strength and Conditioning Research review mentioned above. Aerobic athletes who added strength training to their programs lost body fat, while aerobic training alone did not lead to fat loss.

Practice Judo or Martial Arts
Start practicing judo or a similar martial art to increase antioxidant capacity and decrease oxidative stress. A study in the Journal of Strength and Conditioning Research found that practicing judo can increase resting antioxidant levels that counteract the oxidative stress produced during strenuous exercise.  Researchers compared the effects of a mixed exercise protocol that included an all-out sprint Wingate test followed by 30 minutes of aerobic exercise at 60 percent of maximal aerobic power in judokas and sedentary subjects.

Both groups had similarly elevated free radical levels after the exercise test, but the judokas had much greater total antioxidant status at all time points before and after the test than the sedentary group. The judokas’ elevated antioxidant levels indicate a protective effect against the oxidative stress of aerobic exercise. This is the same positive health effect that strength training provides for aerobic trainees, and it’s likely that yoga or other martial arts, such as tae kwon do, will also elevate antioxidants to counteract the many negatives of aerobic training. Such practices may also lower cortisol if they have a calming effect on the body

Take Creatine to Lower Inflammation and Oxidative Stress
Take creatine to lower inflammatory biomarkers and oxidative stress from aerobic training. There are all kinds of benefits from supplementing with creatine because it is the first energy source called on by the body—it’s been shown to increase work capacity and power, elevate protein synthesis after strength training, improve skill execution when tired, and lower oxidative stress from aerobic training.

Recent research shows creatine can inhibit oxidative stress markers following acute aerobic exercise in rats. A study in Amino Acids found that giving creatine to rats that performed moderate aerobic exercise raised antioxidant levels in the blood, which resulted in lower oxidative stress and less lipid peroxidation than a control group that got no creatine. A second study in the European Journal of Applied Physiology tested different inflammatory biomarkers and found similarly protective effects from creatine supplementation after aerobic exercise. In both cases, researchers think that creatine increased antioxidant capacity that was able to scavenge the free radicals.

Although these studies showed creatine to be effective to counter the inflammatory response of acute training, it is applicable to the longer term negative effects of aerobic training as well. Evidence into the role of creatine on chronic inflammation without aerobic training supports this. One study in the British Journal of Nutrition showed that adding creatine to the diet of rats resulted in greater blood antioxidant content and lower inflammatory biomarkers than a control group that did not consume additional creatine.

Supplement With Omega-3s to Reduce Inflammation
Omega-3s are a well accepted supplement to fight inflammation from many sources, and they have been shown to significantly lower oxidative stress markers from aerobic endurance exercise. There are at least 40 studies in the last two years supporting the protective effect of omega-3s on oxidative stress. In fact, the New York City Marathon organizers should give all runners a bottle of omega-3s to combat the damage they are doing to their bodies by running 26 miles.

A 2009 study in Lipids in Health and Disease measured the effect of omega-3 supplementation on inflammatory biomarkers in men with a history of performing aerobic training. Researchers note that the oxidative stress caused by training can overwhelm the body’s available antioxidant defenses and damage tissues—especially reproductive organs. The subjects in this study were males who exercised at least three days a week for 30 minutes. They were given a total of 4000 mg of omega-3s daily for six weeks, while continuing to perform their regular aerobic exercise.

The group that took the omega-3s had lower resting levels of inflammation after six weeks than a control group that did not supplement. Researchers suggest the protective effects of the omega-3s may have been greater if participants had regularly done more intense aerobic training—in this study their training wasn’t monitored, it just had to be three days a week for thirty minutes.

[A product that I use that provides high quality omega-3 fats is IsaOmega Supreme by Isagenix. I take 2 capules per day that come in their Ageless Essentials with Product B packs (you can also get IsaOmega seperately on its own). For more info on Ageless Essentials with Product B click here and for info on IsaOmega Supreme click here].

Top Five Ways To Protect Yourself From the Negatives of Aerobic Training
1)    Do strength and anaerobic training instead.
2)    Do strength training in addition to your aerobic training.
3)    Get lots of antioxidants: vitamin E, selenium, zinc, red raspberries, tart cherries, etc.
4)    Take creatine.
5)    Take omega-3s.

PS. Come join us at The Maker's Body CrossFit for a free class tryout by visiting www.MakersBody.com.




Charles Poliquin is one of the most accomplished strength coaches in the world. He has designed workouts for Olympic medalists in 17 different sports, world record holders in 10 different sports, and professional athletes in the NBA, NFL, NHL, MLB, and UK Premier League. He has lectured or consulted for a variety of high-profile organizations such as the US Secret Service, Walt Disney Corporation and the World Swimming Congress. More info visit his website at http://www.charlespoliquin.com.

References:
Sen, Chandan. Antioxidants in Exercise Nutrition. Sports Medicine. 2001. 31(13), 891-908.

Michigan, A., Johnson, T., et al. Review of the Relationship between C-Reactive Protein and Exercise. Molecular Diagnosis and Therapy. October 2011. 15(5), 265-275.

Manna, I., Jana, K., Samanta, P. Intensive Swimming Exercise-Induced Oxidative Stress and Reproductive Dysfunction in Male Wistar Rats: Protective Role of Alpha-Tocopherol Succinate. Canadian Journal of Applied Physiology. April 2004. 29(2), 172-185.

Cakir-Atabek, H., Demir, S., Pinarbassili, R., Bunduz, N. Effects of Different Resistance Training Intensity on Indices of Oxidative Stress. Journal of Strength and Conditioning Research. September 2010. 24(9), 2491-2498.

Walsh, N., Gleeson, M., et al. Position Statement. Part One: Immune Function and Exercise. Exercise Immunology Review. 2011. 17, 6-63

Wilson, J., Marin, P., et al. Concurrent Training: A Meta Analysis Examining Interference of Aerobic and Resistance Exercise. Journal of Strength and Conditioning Research. October 2011. Published Ahead of Print.

Boutcher, Stephen H. High-Intensity Intermittent Exercise and Fat Loss. Journal of Obesity. 2011. http://www.hindawi.com/journals/jobes/2011/868305/

 Shojaei, E., Farajoy, A., et al. Effect of Moderate Aerobic Cycling on Some Systemic Inflammatory Markers in Healthy Active Collegiate Men. International Journal of General Medicine. January 2011. 24(2), 79-84.

Jana, K., Samanta, P., Manna, I., Ghosh, P., Singh, N., Khetan, R., Ray, B. Protective Effect of Sodium Selenite and Zinc Sulfate on Intensive Swimming-Induced Testicular Gamatogenic and Steroidogenic Disorders in Mature Male Rats. Applied Physiology, Nutrition, and Metabolism. October 2008. 33(5), 903-914.

Marzatico, F., Pansarasa, O., et al. Blood Free Radical Antioxidant Enzymes and Lipid Peroxides Following Long-Distance and Lactacidemic Performances in Highly Trained and Aerobic and Sprint athletes. Journal of Sports Medicine and Physical Fitness. 1997. 37, 235-239.

Packer, L. Oxidants, Antioxidant Nutrients, and the Athlete. Journal of Sports Science. June 1997. 15(3), 353-363.

Martarelli, D., Verdenelli, M., et al. Effect of a Probiotic Intake on Oxidant and Antioxidant Parameters in Plasma of Athletes During Intense Exercise Training. Current Microbiology. June 2011. 62(6), 1689-1696.

Skoluda, N., Dettenborn, L., et al. Elevated Hair Cortisol Concentrations in Endurance Athletes. Psychoneuroendocrinology. September 2011. Published Ahead of Print.

Gleeson, Michael. Immune Function in Sport and Exercise. Journal of Applied Physiology. February 2007. 103(2), 693-699.

Bloomer, R., Larson, D., et al. Effect of Eicosapentaenoic and Docosahexaenoic Acid on Resting and Exercise-Induced Inflammatory and Oxidative Stress Biomarkers: A Randomized, Placebo Controlled, Cross-Over Study. Lipids in Health and Disease. August 2009. 8(36).

Oostenbrug, G., Mensink, R., et al. Exercise Performance, Red Blood Cell Deformability, and Lipid Peroxidation: Effects of Fish Oil and Vitamin E. Journal of Applied Physiology. 1997. 83(3), 746-752.

Deminice, R., Portari, V., et al. Effects of Creatine Supplementation on Homocysteine Levels and Lipid Peroxidation in Rats. The British Journal of Nutrition. 2009. 102, 110-116.

Deminice, R., Vannucchi, H., et al. Creatine Supplementation Reduces Increased Homocysteine Concentration Induced by Acute Exercise in Rats. European Journal of Applied Physiology. 2011. 111, 2663-2670.

Deminice, R., Jordao, A. Creatine Supplementation Reduces Oxidative Stress Biomarkers After Acute Exercise in Rats. Amino Acids. October 2011. Published ahead of Print.

Abed, K., Rebai, H., Bloomer, R., Trabelsi, K., Masmoudi, L., Zbidi, A., Sahnoun, Z., Hakim, A., Tabka, Z. Antioxidant Status and Oxidative Stress at Rest and in Response to Acute Exercise in Judokas and Sedentary Men. Journal of Strength and Conditioning Research. August 2011. 25(9), 2400-2409.

Taixeira, V., Valente, H., Casal, S., Marques, F., Moreira, P. Antioxidant Status, Oxidative Stress and Damage in Elite Trained Kayakers and Canoeists and Sedentary Controls. International Journal of Sport Nutrition and Exercise Metabolism. October 2009. 19(5), 443-456.

Ghosh, D., Das, U., et al. Protective Effect of Provitamin D in Cyclophosphamide Induced Testicular Gametogenic and Steroidogenic Disorders: a Correlative Approach to Oxidative Stress. Free Radical Research. 2002. 36(11), 1209-1218.

Aagaard, P., Andersen, J., et al. Effects of Resistance Training on Endurance Capacity and Muscle Fiber Composition in Young Top-Level Cyclists. Scandinavian Journal of Medicine and Science in Sports. March 2011. Published Ahead of Print.

Martarelli, D., Verdenelli, M., et al. Effect of a Probiotic Intake on Oxidant and Antioxidant Parameters in Plasma of Athletes During Intense Exercise Training. Current Microbiology. June 2011. 62( Tweet This