Is Your Favorite Sport Secretly Killing You? 6 Steps to Protecting Your Heart from Extreme Endurance Exercise.

Affiliate Disclosure

Anti-Aging, Articles

The following is a guest post by my friend and fellow triathlete Armi Legge…leave your questions, comments and feedback below the article. This post was released the day before the Boston Marathon tragedies, and was not meant in any way to coincide with those unfortunate events.

If you’re an endurance athlete, you’ve probably seen articles claiming that your favorite sport is secretly killing you.

Do a Google search for “endurance exercise heart damage,” and you’ll find about 2,530,000 results, and countless articles that may make you think twice about your next workout.

Without getting into obsessive detail about every study on this topic, it’s safe to say the dangers of endurance sports are overblown.

That said, there are still risks that long-term endurance exercise could cause heart problems in some athletes. The risks may also be higher for athletes who are pushing the limits of performance, trying to maximize their results through more intense training.

Well-trained endurance athletes may actually have a higher risk of heart damage, since they can push themselves harder for longer (i.e. they have more endurance).(1)

There is no direct research on how to protect your heart from endurance exercise (largely because most research indicates it’s only an issue for a small minority of athletes).(2,3) However, studies have given us some clues as to how we can minimize the risks of endurance sports damaging our hearts.

Get The Low Carb Athlete - 100% Free!Eliminate fatigue and unlock the secrets of low-carb success. Sign up now for instant access to the book!

Here’s exactly what you need to know…

Protect Your Heart from Extreme Endurance Exercise in 6 Simple Steps

None of these solutions have been tested in randomized controlled trials, and they will not guarantee that exercise won’t damage your heart. That said, these are the most practical, simple steps that are based on the best available evidence.

1. Plan Adequate Rest

Researchers think that if “myocardial injury” (heart damage), sometimes occurs during endurance exercise, it’s similar to a training injury. The cause may also be similar — doing too much, too soon.(4-7)

Like other muscles, your heart is fatigued after a workout and needs time to recover.(8-11)In general, the harder and longer the workout, the more time it takes for heart function to return to normal.

There’s no data measuring this directly, but it’s likely your heart fatigues at a similar rate as your muscles. The demands on your heart during exercise are mostly proportional to how hard your muscles are working.

Basically, once your muscles are recovered, your heart probably is too.

The best way to know if your heart is recovered is to get an echocardiogram or an MRI, but this probably isn’t necessary. If you’re muscles are sore and fatigued, and you feel lethargic and unmotivated, your heart is probably not completely recovered. If you feel great, your heart is probably ready for another hard workout.

Here are a few tips to make sure your heart is recovering from your endurance workouts:

  • Plan and periodize your season, so you can gradually increase your volume and intensity.
  • Insert recovery weeks throughout your season where you decrease the volume and intensity for a few days. This helps shake off any lasting fatigue before the next series of workouts.
  • Don’t destroy yourself every day in training. It’s not necessary, productive, or healthy.
  • When in doubt, train less rather than more.

——————————–

2. Don’t Train When You’re Sick

If you have a serious infection, don’t train.

Exercise tends to improve immune function over time, but too much training can have the opposite effect.(12-15)If you overtrain or overreach too often, you may increase your risk of developing myocarditits – a heart infection.

About 90% of people will eventually catch one of the same viruses that causes myocarditis, yet it rarely infects the heart.(16) If you’re overtraining, the chances of the disease progressing to your heart are probably higher.

Other seemingly less severe diseases like the flu can also increase the risk of myocarditis.(17)

“It is possible that this may be severe enough to cause permanent heart damage but yet the person does not feel too unwell at the time,” writes Dr. Andre La Gerche, the author of several papers on this topic.

“It is also possible that athletes are at greater risk of this because there is some evidence that exercise can compound the effects of ‘myocarditis’ and athletes will often train through anything,” continues Dr. La Gerche.

It’s still not clear if exercise causes immune function to drop.(18)Even if it does, it’s not clear if this increases your risk of developing myocarditis in particular. Only one study found a high rate of myocarditis in athletes, but it’s plausible overtraining may have contributed.(19)

In any case, if you’re already sick, hard training is probably not going to help you recover from an infection faster.(20,21)

It’s probably safe to push through minor illnesses like a cold. However, more serious infections may pose a greater risk to your heart.

——————————–

3. Be Patient

Endurance athletes are ambitious people. We like to go longer, faster, and harder, often sooner than we should.

It’s not uncommon for athletes to race a marathon or Ironman after a year or two of training.

This probably isn’t the best idea in terms of heart health. It takes years of consistent training to prepare your heart for something like an ironman, half-ironman, or even a marathon. It takes time for your heart to adapt and grow larger, stronger, and more efficient.(22,23)

One study also found that better trained athletes’ hearts had a smaller rise in markers of heart stress after extreme exercise (though not many studies have looked at this relationship).(24) Most studies have also found that the hearts of athletes who train more don’t get as fatigued after exercise.(25)

That said, most recreational athletes may not be able to push themselves as hard or long as more experienced ones, which might reduce the risks. If you’re determined to start long races (2+ hours) in your first few years of training, try to finish, rather than compete.

——————————–

4. Be Specific with Your Training

Your heart adapts specifically to the kind of exercise you do most.(26-28)

Similar sports tend to produce more similar changes, but they’re still slightly different. Runners and cyclists often have much larger hearts than non-athletes, but there are still subtle differences in the thickness of the heart walls and shape of the chambers.(29,30)

There hasn’t been any research on whether or not an athlete with a “swimmer’s heart” is more likely to suffer heart damage if they suddenly start running marathons. They probably aren’t.

That said, an athlete whose heart is well adapted to one sport is probably not fully prepared for the cardiovascular demands of another. If you want to do everything you can to minimize the chances that endurance exercise might damage your heart, train your heart for your sport.

If you want your heart to be ready for a marathon, lifting weights won’t cut it. You need to run — a lot.*

*Note from yours truly – I don’t necessarily agree with Armi about needing to run a lot IF you are using HIIT.

——————————–

5. Listen to Your Body

Endurance athletes are good at ignoring pain, fatigue, and discomfort.

When it comes to the health of your heart, this isn’t always good.

If you ever experience any of the following symptoms during or after exercise, see a doctor as soon as possible. These are often signs of heart disease.(31-33)

  • Chest pain (especially on the left side).
  • Dyspnea (the inability to catch your breath, even at a moderate to low effort).
  • Unexplained nausea and/or dizziness.
  • Extreme fatigue or lethargy despite being well rested.

These symptoms can be caused by things other than heart disease, so don’t freak out if they happen to you. That said, it’s best to see a doctor to be safe.

——————————–

6. Get Your Heart Tested

If you’re really concerned about endurance exercise damaging your heart, it’s a good idea to get a check-up, or more thorough testing in some cases.

There’s still ongoing debate about whether or not athletes should get a detailed series of heart tests before they start exercising, especially if they don’t have any symptoms.(34-39)That said, most experts think it’s a good idea to at least get an electrocardiogram (ECG) and basic examination if you can afford it.(40-48)

If you’re over the age of 50, it may also be a good idea to get a coronary calcium scan to see how much, if any, plaque is in your arteries.(49,50) Some data suggests that endurance athletes (specifically, marathon runners), may have more than you’d normally expect for otherwise healthy athletes.(51)

None of these tests are 100% foolproof, and it’s still possible to have heart problems despite excellent test results.(52,53) It’s also important to give your doctor a detailed medical history so they can help you decide how much exercise is safe for your heart.*

*In addition to what Armi recommends, I’d also seriously consider checking out variables such as inflammatory markers (i.e. C-Reactive Protein), potassium and magnesium levels, etc. Check out the article “How To Test Your Body“.

——————————–

Summary: Exercise Sensible Caution when it Comes to “Cardio” and Your Heart

There are real risks when it comes to endurance exercise and your heart. They’re smaller than many people would have you believe, but they do exist.

If you’ve been adhering to these tips, the chances that your training may damage your heart, or has damaged your heart, are slim.

There aren’t nearly enough studies to say definitely how likely it is that endurance exercise might damage your heart, or how to reduce these risks. Luckily, there’s enough research to develop a few educated guesses on how you can keep “cardio” from damaging your heart.

You can find more articles on whether or not endurance sports are bad for you on Imprüvism.com. Here’s a good place to start.

Disclosures: I am a long time endurance athlete and currently compete on an elite triathlon team. I am willing to accept that excessive endurance exercise contributes to heart disease if the evidence supports that conclusion, but I also admit a certain level of bias in that I hope it does not. I am also not a doctor, and this is not medical advice.

Questions, comments or feedback? Leave them below.

———————————–

References

1. La Gerche A, Burns AT, Mooney DJ, et al. Exercise-induced right ventricular dysfunction and structural remodelling in endurance athletes. Eur Heart J. 2012 Apr;33(8):998-1006. | Abstract: http://pmid.us/22160404 | Full Text: Received from author (with editorial).

2. Baggish AL, Wood MJ. Athlete’s heart and cardiovascular care of the athlete: scientific and clinical update. Circulation. 2011 Jun 14;123(23):2723-35. Abstract: http://pmid.us/21670241 | Full Text: http://goo.gl/fWiEj

3. Maron BJ, Pelliccia A. The heart of trained athletes: cardiac remodeling and the risks of sports, including sudden death. Circulation. 2006 Oct 10;114(15):1633-44. Abstract: http://pmid.us/17030703 | Full Text: http://goo.gl/qirCb | Author Contact: <hcm.maron@mhif.org>

4. Patil HR, O’keefe JH, Lavie CJ, et al. Cardiovascular damage resulting from chronic excessive endurance exercise. Mo Med. 2012 Jul-Aug;109(4):312-21. Abstract: http://pmid.us/22953596 | Full Text: http://goo.gl/pxtJj | Author Contact: <jokeefe@saint-lukes.org>

5. O’keefe JH, Patil HR, Lavie CJ, et al. Potential adverse cardiovascular effects from excessive endurance exercise. Mayo Clin Proc. 2012;87(6):587-95. Abstract: http://pmid.us/22677079 | Full Text: http://goo.gl/Q5MmQ

6. Wilson MG, Whyte GP. Is life-long exercise damaging to the heart? Br J Sports Med. 2012 Jul;46(9):623-4. Abstract: http://pmid.us/22345624 | Full Text: Received from author.

7. O’Keefe JH, Lavie CJ. Run for your life … at a comfortable speed and not too far. Heart. 2012 Nov 29. Abstract: http://pmid.us/23197444 | Full Text: Received from author.

8. Dawson E, George K, Shave R, et al. Does the human heart fatigue subsequent to prolonged exercise? Sports Med. 2003;33(5):365-80. Abstract: http://pmid.us/12696984 | Full Text: Received from author. | Author Contact: <e.dawson@ljmu.ac.uk>

9. Middleton N, Shave R, George K, et al. Left ventricular function immediately following prolonged exercise: a meta-analysis. Med Sci Sports Exerc 2006;38:681 – 687. Abstract: http://pmid.us/16679983 | Full Text: Received from author. | Author Contact: <natalie.middleton@brunel.ac.uk>

10. Shave R, George K, Whyte G, et al. Postexercise changes in left ventricular function: the evidence so far. Med Sci Sports Exerc. 2008 Aug;40(8):1393-9. Abstract: http://pmid.us/18614954 | Full Text: Received from author.

11. Oxborough D, Birch K, Shave R, et al. “Exercise-induced cardiac fatigue”–a review of the echocardiographic literature. Echocardiography. 2010 Oct;27(9):1130-40. Abstract: http://pmid.us/20678128 | Full Text: Received from author.

12. Walsh NP, Gleeson M, Shephard RJ, et al. Position statement. Part one: Immune function and exercise. Exerc Immunol Rev. 2011;17:6-63. Abstract: http://pmid.us/21446352 | Full Text: http://goo.gl/ft9jz

13. Gleeson M. Immune function in sport and exercise. J Appl Physiol. 2007 Aug;103(2):693-9. Abstract: http://pmid.us/17303714 | Full Text: http://goo.gl/FFavk

14. Rowbottom DG, Green KJ. Acute exercise effects on the immune system. Med Sci Sports Exerc. 2000 Jul;32(7 Suppl):S396-405. Abstract: http://pmid.us/10910296 | Full Text: NA

15. MacKinnon LT. Special feature for the Olympics: effects of exercise on the immune system: overtraining effects on immunity and performance in athletes. Immunol Cell Biol. 2000 Oct;78(5):502-9. Abstract: http://pmid.us/11050533 | Full Text: http://goo.gl/57KhL

16. Dennert R, Crijns HJ, Heymans S. Acute viral myocarditis. Eur Heart J. 2008 September; 29(17): 2073–2082. Full Text: http://goo.gl/cEqfZ

17. Ukimura A, Satomi H, Ooi Y, et al. Myocarditis Associated with Influenza A h3N1pdm2009. Influenza Res Treat. 2012;2012:351979. Abstract: http://pmid.us/23304476 | Full Text: http://goo.gl/vw34u

18. Gleeson M. Immune system adaptation in elite athletes. Curr Opin Clin Nutr Metab Care. 2006 Nov;9(6):659-65. Abstract: http://pmid.us/17053416 | Full Text: NA

19. Wesslén L, Pahlson C, Lindquist O, et al. An increase in sudden unexpected cardiac deaths among young Swedish orienteers during 1979–1992. Eur Heart J.1996; 17: 902–910. Abstract: http://pmid.us/8781830 Full Text: http://goo.gl/H0YgO

20. Schultz JC, Hilliard AA, Cooper LT Jr, et al. Diagnosis and treatment of viral myocarditis. Mayo Clin Proc. 2009 Nov;84(11):1001-9. Abstract: http://pmid.us/19880690 | Full Text: http://goo.gl/2eAyK

21. Friman G, Ilbäck NG. Acute infection: metabolic responses, effects on performance, interaction with exercise, and myocarditis. Int J Sports Med. 1998 Jul;19 Suppl 3:S172-82. Abstract: http://pmid.us/9722283 | Full Text: NA

22. Prior DL, La Gerche A. The athlete’s heart. Heart. 2012 Jun;98(12):947-55. Abstract: http://pmid.us/22626903 | Full Text: Received from author.

23. George K, Spence A, Naylor LH, et al. Cardiac adaptation to acute and chronic participation in endurance sports. Heart. 2011 Dec;97(24):1999-2004. Abstract: http://pmid.us/22058283 | Full Text: Received from author. | Author Contact: <K.George@ljmu.ac.uk>

24. Neilan TG, Januzzi JL, Lee-lewandrowski E, et al. Myocardial injury and ventricular dysfunction related to training levels among nonelite participants in the Boston marathon. Circulation. 2006;114(22):2325-33. http://pmid.us/17101848 | Full Text: http://goo.gl/QCHh9

25. Middleton N, Shave R, George K, et al. Left ventricular function immediately following prolonged exercise: a meta-analysis. Med Sci Sports Exerc 2006;38:681 – 687. Abstract: http://pmid.us/16679983 | Full Text: Received from author. | Author Contact: <natalie.middleton@brunel.ac.uk>

26. Pluim BM, Zwinderman AH, Van der laarse A, et al. The athlete’s heart. A meta-analysis of cardiac structure and function. Circulation. 2000;101(3):336-44. Abstract: http://pmid.us/10645932 | Full Text: http://goo.gl/DUQMk

27. Baggish AL, Wood MJ. Athlete’s heart and cardiovascular care of the athlete: scientific and clinical update. Circulation. 2011 Jun 14;123(23):2723-35. Abstract: http://pmid.us/21670241 | Full Text: http://goo.gl/fWiEj

28. George K, Spence A, Naylor LH, et al. Cardiac adaptation to acute and chronic participation in endurance sports. Heart. 2011 Dec;97(24):1999-2004. Abstract: http://pmid.us/22058283 | Full Text: Received from author. | Author Contact: <K.George@ljmu.ac.uk>

29. Fagard R, Aubert A, Staessen J, et al. Cardiac structure and function in cyclists and runners. Comparative echocardiographic study. Br Heart J. 1984 August; 52(2): 124–129. Full Text: http://goo.gl/8XOlm

30. Pluim BM, Zwinderman AH, Van der laarse A, et al. The athlete’s heart. A meta-analysis of cardiac structure and function. Circulation. 2000;101(3):336-44. Abstract: http://pmid.us/10645932 | Full Text: http://goo.gl/DUQMk

31. Maron BJ. Hypertrophic cardiomyopathy: a systematic review. JAMA. 2002 Mar 13;287(10):1308-20. Abstract: http://pmid.us/11886323 | Full Text: http://goo.gl/DKULN

32. Davies SW. Clinical presentation and diagnosis of coronary artery disease: stable angina. Br Med Bull. 2001;59:17-27. Abstract: http://pmid.us/11756201 | Full Text: http://goo.gl/jKdTl

33. Leuzzi C, Modena MG. Coronary artery disease: clinical presentation, diagnosis and prognosis in women. Nutr Metab Cardiovasc Dis. 2010 Jul;20(6):426-35. Abstract: http://pmid.us/20591634 | Full Text: NA

34. Baggish AL, Wood MJ. Athlete’s heart and cardiovascular care of the athlete: scientific and clinical update. Circulation. 2011 Jun 14;123(23):2723-35. Abstract: http://pmid.us/21670241 | Full Text: http://goo.gl/fWiEj

35. Maron BJ. Distinguishing hypertrophic cardiomyopathy from athlete’s heart physiological remodelling: clinical significance, diagnostic strategies and implications for preparticipation screening. Br J Sports Med. 2009 Sep;43(9):649-56. Abstract: http://pmid.us/19734498 | Full Text: NA

36. Estes NA 3rd, Link MS. Preparticipation athletic screening including an electrocardiogram: an unproven strategy for prevention of sudden cardiac death in the athlete. Prog Cardiovasc Dis. 2012 Mar-Apr;54(5):451-4. Abstract: http://pmid.us/22386297 | Full Text: NA

37. Lawless CE, Best TM. Electrocardiograms in athletes: interpretation and diagnostic accuracy. Med Sci Sports Exerc. 2008 May;40(5):787-98. Abstract: http://pmid.us/18408622 | Full Text: NA

38. Maron BJ, Pelliccia A. The heart of trained athletes: cardiac remodeling and the risks of sports, including sudden death. Circulation. 2006 Oct 10;114(15):1633-44. Abstract: http://pmid.us/17030703 | Full Text: http://goo.gl/qirCb | Author Contact: <hcm.maron@mhif.org>

39. Papadakis M, Chandra N, Sharma S. Controversies relating to preparticipation cardiovascular screening in young athletes: time for a realistic solution? Br J Sports Med. 2011 Mar;45(3):165-6. Abstract: http://www.ncbi.nlm.nih.gov/pubmed/19846425 | Full Text: http://goo.gl/9JVwe

40. Baggish AL, Wood MJ. Athlete’s heart and cardiovascular care of the athlete: scientific and clinical update. Circulation. 2011 Jun 14;123(23):2723-35. Abstract: http://pmid.us/21670241 | Full Text: http://goo.gl/fWiEj

41. Corrado D, Pelliccia A, Bjørnstad HH, et al. Cardiovascular pre-participation screening of young competitive athletes for prevention of sudden death: proposal for a common European protocol. Eur Heart J. 2005 Mar;26(5):516-24. http://pmid.us/15689345 | Full Text: http://goo.gl/VrcPW

42. Asif IM, Drezner JA. Sudden cardiac death and preparticipation screening: the debate continues-in support of electrocardiogram-inclusive preparticipation screening. Prog Cardiovasc Dis. 2012 Mar-Apr;54(5):445-50. Abstract: http://pmid.us/22386296 | Full Text: NA

43. Drezner J, Corrado D. Is there evidence for recommending electrocardiogram as part of the pre-participation examination? Clin J Sport Med. 2011

Jan;21(1):18-24. Abstract: http://pmid.us/21200166 | Full Text: http://goo.gl/B6EsI

44. Drezner J, Berger S, Campbell R. Current controversies in the cardiovascular screening of athletes. Curr Sports Med Rep. 2010 Mar-Apr;9(2):86-92. Abstract: http://pmid.us/20220349 | Full Text: NA

45. Borjesson M, Dellborg M. Is there evidence for mandating electrocardiogram as part of the pre-participation examination? Clin J Sport Med. 2011 Jan;21(1):13-7. Abstract: http://pmid.us/21200165 | Full Text: NA

46. Drezner JA. Contemporary approaches to the identification of athletes at risk for sudden cardiac death. Curr Opin Cardiol. 2008 Sep;23(5):494-501. Abstract: http://pmid.us/18670262 | Full Text: NA

47. Maron BJ, Douglas PS, Graham TP, et al. Task Force 1: preparticipation screening and diagnosis of cardiovascular disease in athletes. J Am Coll Cardiol. 2005 Apr 19;45(8):1322-6. Abstract: http://pmid.us/15837281 | Full Text: http://goo.gl/z46hH

48. Corrado D, Pelliccia A, Heidbuchel H, et al. Recommendations for interpretation of 12-lead electrocardiogram in the athlete. Eur Heart J. 2010 Jan;31(2):243-59. Abstract: http://pmid.us/19933514 | Full Text: http://goo.gl/23LIY

49. Yared K, Wood MJ. Is marathon running hazardous to your cardiovascular health? The jury is still out. Radiology. 2009 Apr;251(1):3-5. Abstract: http://pmid.us/19332839 | Full Text: http://goo.gl/FpfKG

50. Schmermund A, Voigtländer T, Nowak B. The risk of marathon runners-live it up, run fast, die young? Eur Heart J. 2008 Aug;29(15):1800-2. Abstract: http://pmid.us/18556710 | Full Text: http://goo.gl/OpC48

51. Möhlenkamp S, Lehmann N, Breuckmann F, et al. Running: the risk of coronary events : Prevalence and prognostic relevance of coronary atherosclerosis in marathon runners. Eur Heart J. 2008;29(15):1903-10. Abstract: http://pmid.us/18426850 | Full Text: http://goo.gl/BHcsX

52. Rowin EJ, Maron BJ, Appelbaum E, et al. Significance of false negative electrocardiograms in preparticipation screening of athletes for hypertrophic cardiomyopathy. Am J Cardiol. 2012 Oct 1;110(7):1027-32. Abstract: http://pmid.us/22809754 | Full Text: NA

53. Drezner JA, Asif IM, Owens DS, et al. Accuracy of ECG interpretation in competitive athletes: the impact of using standised ECG criteria. Br J Sports Med. 2012 Apr;46(5):335-40. Abstract: http://pmid.us/22310648 | Full Text: http://goo.gl/UJLaL

Ask Ben a Podcast Question


11 thoughts on “Is Your Favorite Sport Secretly Killing You? 6 Steps to Protecting Your Heart from Extreme Endurance Exercise.

  1. Extreme Sports says:

    It is really important to make sure that our health is in good condition before engaging into extreme sports, now I am fully aware that I can't just join a marathon whenever I wanted to. I have to undergo a training before joining one.

  2. Jay says:

    Good thing I found this info. About to hit the gym hard and training a lot this summer. Love your site, going to read some more info. You should post more endurance training stuff :)

    Jay.

  3. Reka says:

    The title I got in your newsletter is a bit misleading for me, as running is actually one of my least favourite sports.

  4. Doris says:

    Hey Ben, I'd also be interested in your views on endurance athletes and pulmonary embolisms. FYI, I completed the 250km RTP Sahara Race in Oct/Nov 2012, and 6 weeks later I was in hospital with a PE. Doctors are still unsure what caused it (they speculated whether the race was a contributing factor, but it's not clear). The symptoms of PEs are similar to a heart attack (chest pain, dyspnea, fatigue) and also potentially fatal (lucky for me I was diagnosed and treated). I've been reading up on PEs since, and it seems that PEs among endurance athletes are not uncommon, so perhaps a future article on this topic…?

    1. armilegge says:

      Hey Doris, Interesting experience. I'm sorry you had to go through that, but congrats on finishing. Maybe I'll write another article on that as well.

  5. Wayne says:

    This is all mostly rehashed info — but accurate and well worth a read. I agree with Armi and the summation of the research. Notably, these data points and facts, among others, are some of the reasons that I and my MD spouse find serious fault in the HIIT fad that has popped up over the last few years. (Sorry Ben! :-) I would especially underscore point 3 and 4, Be Patient and Be Specific.

    1. I think the bigger take away point here is don't do HIIT for swimming if you're a marathoner. Or HIIT on the bike if you're a swimmer. That's the idea of specificity. Intensity specificity is not as important (i.e. even if running a marathon aerobically, anaerobic efforts can still give benefit)…

      1. armilegge says:

        @Wayne
        Yes, most of it is pretty common sense, yet as you said, it bears repeating. I agree with you in that I'm more in favor of a higher volume approach (depending on the individual and their goals), but in the context of cardiovascular health, you're probably safe using mostly HIIT to prepare for long events as Ben does.

        @Ben Much agreed Ben. Also worth noting that even seemingly anaerobic HIIT style training is mostly aerobic after the first few efforts. <a href="http://(http://ajpendo.physiology.org/content/277/5/E890.short)” target=”_blank”>(http://ajpendo.physiology.org/content/277/5/E890.short)

  6. Joshua says:

    read pete egoscues book

    the egoscue method

    1. Why do you recommend that one, Josh?

    2. armilegge says:

      What are the principles behind the book, and how do they relate to the cardiovascular effects of endurance training?

Leave a Reply

Your email address will not be published. Required fields are marked *