Do You Really Need Aerobics? Rethinking The Need For Cardio
See Kevin’s Video: Don’t Do Cardio To Lose Weight | Understanding Cardio And Muscle Loss
Walk into any major gym in America and the first thing you will see is the cardio equipment. Mention the word ‘exercise’ and for most people the first images to come to mind are aerobic in nature- running, treadmills, Zumba classes, elliptical machines, Stairmasters and the like. Say ‘weight loss’ and the images get sharper, as it is a commonly held position that you need to do cardio if you want to lose weight and maintain a healthy body weight. Gyms are filled with people eager to shed a few extra pounds, and yet in spite of the innumerable number of hours spent sweating, few ever attain the lean and sculpted look that has become the Holy Grail of our time. Most of us double our efforts after seeing so little in terms of improvement after slaving away doing hours of aerobics in the hope that maybe just a little more of the same will bring us that all-so elusive look. We persist for months, sometimes for years, trying to eat better and train harder until finally, over-trained, frustrated and very often injured, we quit. Relegating ourselves to the ranks of those-who-can’t-lose-weight-because-of-bad-genes. It can be an incredibly disheartening and depressing experience to do so much work and get so little back in terms of tangible changes in your body, but it most of the time has nothing to do with our inability to lose weight. In most cases the blame lies squarely on the fact that cardio is not an efficient method for weight loss and that it simply cannot give you the toned and trim body of your dreams. Millions can attest by their lack of results, that using aerobics as a tool for getting in shape is driven primarily by advertising and misinformation, not results. And yet many experts in the field cling to the idea that cardio is an irreplaceable part of any fitness regime. The science of how our bodies work don’t support this notion, nor do the countless number of frustrated gym goers still waiting to see their six packs. In my practice as a personal trainer in NYC I am constantly amazed by how many other trainers use cardio as the centerpiece of their weight loss programs. The reality is that you don’t need cardio and anaerobic resistance exercise alone can provide superior results in terms of weight loss, increasing endurance and improving overall health parameters.
Cardio and Weight Loss- The Case For Anaerobic Exercise Over Aerobics
It goes without saying that if everyone who ever ventured out regularly for a run or frequented a cardio machine was able to lose weight and keep it off that we would have had a simple solution to our growing obesity problems several decades ago, (as well as an influx of six pack sporting magazine cover models.) We all know this not to be the case and many recent studies affirm what so many have learned the hard way, namely that cardio is a poor method of weight management. One study published in the British Journal of Sports Medicine tracked the results of 58 sedentary overweight/obese men and women who participated in a 12 week course of supervised aerobic exercise. The results were positive in terms of increased endurance and decreased systolic and diastolic pressure but not at all glowing in terms of weight loss. The mean weight loss was only a bit over seven pounds in three months, with most of the group losing barely half of that amount. [1]
The amount of calories burned during aerobic exercise is not as much as we would think as well. Consider the fact that to lose a pound of fat you need to burn 3,500 kcal- which may not sound like much, but to lose 1 lb of fat a 190 lb man would have to run a full 26 mile marathon. To lose 5 lbs he would have to run 5 marathons and a 155 lb woman would have to run even further at a pretty fast pace! Which shows just how extreme the amount of aerobics you need in order to lose weight. At the far end of the spectrum, endurance athletes and those who devote an enormous amount of time to very long workouts can keep their body weight down, but they won’t sport the well muscled and chiseled physiques that most hold as today’s Holy Grail, and they will gain a significant amount of weight if they ever stop. Which is often the case with endurance athletes who come to me after they stop training when either injury or lack of time prevents them from long distance training and they find it difficult to almost impossible to maintain a low body fat percentage.
In terms of fat burning, new research has continued to show that short high intensity, anaerobic type exercise do far more to reduce body fat than conventional aerobic exercise. A study done at Laval University investigated the impact of aerobics versus high intensity anaerobic exercises on body fat using young adults and the findings were quite eye opening. Participants took part in either a 20 week endurance training regime of sustained aerobics or a 15 week high intensity intermittent training protocol. Despite the fact that participants doing the aerobic exercises expended over twice as much energy as the anaerobic group- (120.4 MJ as opposed to 57.9 MJ), those in the anaerobic group lost significantly more body fat than the cardio exercise group.[2] When corrected for the energy cost of training, the decrease in the sum of six skinfold tests induced by the anaerobic exercise was impressively nine times greater than that of the aerobic group.[2]
Many other studies show similar outcomes. A study done at the University of New South Wales inadvertently found that women taking part in anaerobic high intensity interval training burned fat at a rate three times higher than those doing aerobic exercises.[3] This result came from a total of only 20 minutes of anaerobic exercise on a stationery bike, while the second group exercised at a consistent pace in standard target heart rate zones for twice as long. After 15 weeks, researchers found that the women in the high intensity group lost three times more weight than those who rode the bicycles for twice as much time.[3] A testament to the inefficiency of cardio over more intense anaerobic forms of training. Other studies have found similar patterns with even shorter durations of high intensity anaerobic exercise.
Dispelling The Myth Of Cardio’s Afterburner Effect
For years the party lines for using cardio to promote fat loss have that that increased activity burns more calories- which is true and not at all in dispute and that aerobic exercise elevates the metabolism for prolonged periods after the training session. As standard an idea as this has been for many, it has not stood up to the test of scientific scrutiny, nor has it helped produced a new generation of trim and slim waistlines. The afterburning effect sought by cardio enthusiasts is really what scientists call excess post-exercise oxygen consumption or EPOC. Exercise brings about a change in the equilibrium of our body (See our article on responses to exercise stress here) our body will always do its best to revert to a resting state of homeostasis and this requires an increase in the amount of oxygen (EPOC) which is needed for our bodies to return to its normal state and adapt to the exercise performed. As a result, there is a measurable increase in metabolism and fat burning after exercise. [3,4,5] This increase was originally thought to occur only with aerobic exercise, but studies have shown that it actually is far more prevalent in anaerobic exercise of sufficient intensities.[2]
Cardio And Heart Health- Dispelling The Myth That You Need Cardio For A Healthy Heart
Weight loss aside, you must need some form of cardio to increase your endurance and to keep your heart healthy, right? Again, the science disagrees with what has become practiced convention. Aerobic exercise can indeed increase lung capacity and strengthen the heart muscle which is related to a decrease in cardiovascular disease[6] but it isn’t the only way to do it nor the most efficient. With regards to your heart and lungs it should be noted that
THE CARDIOVASCULAR SYSTEM WORKS TO SUPPORT THE MUSCULAR SYSTEM AND NOT THE OTHER WAY AROUND!
It is physically impossible to train your muscles without working your heart as well. The two are not disconnected, yet this basic fact of physiology is often overlooked in discussions regarding aerobic exercise requirements. Any improvement in muscle mass and strength brought on by anaerobic exercise of adequate intensity will correspond with an improvement in cardiovascular health parameters as well. The impact of a high intensity workout to your cardiovascular system should not be underestimated, and those who argue that it doesn’t stimulate your heart and lungs have simply never executed a compound resistance movement to a point of momentary muscular failure or beyond. Needless to say, a high intensity set of squats to even close to the threshold of muscular failure leaves even the most conditioned of athletes gasping for air. You can’t work muscles at high intensities without significantly elevating your heart rate.
Cardio Is Not The Only Way To Increase Endurance
The idea of a need for repetitive steady state aerobic exercise to improve endurance has been a constant theme in modern sports medicine, however this theory also fails to hold up to the rigors of scientific testing. A study done by Martin Gilba of McMaster University in Ontario found that short, anaerobic high intensity bouts of exercise produced far greater improvements in endurance as compared to conventional aerobics and not only in terms of performance but also with regards to molecular changes in mitochondria related to increased endurance.[7] In one group participants were made to cycle as hard as they could for 20 to 30 seconds for a total of two to three minutes per session while the other group rode a stationary bike at a sustainable pace for 90 to 120 minutes. Each group trained three times a week, and at the end of the two week study both groups showed almost the same increases in overall endurance, with the high intensity anaerobic exercise group having slightly better aerobic performance over their aerobic exercise counterparts, even though they only trained for six to nine minutes a week in while the other group had trained for an weekly average of five hours.[7] Similar findings have been reported in studies by the National Institute of Health and Nutrition in Japan and many experts in the field of sports medicine have begun to question the validity behind the theory of sports specificity for increases in endurance and performance given the new findings on anaerobic high intensity training.[8]
Anaerobic Exercise Conveys The Same Benefits As Aerobics If Not More
So what about the other benefits of aerobic exercise? Pretty much all of them can be replicated or improved upon with resistance exercise of adequate intensity. High intensity anaerobic training has been shown to:
- Improve depression as well as aerobics.[9,10,11,12]
- Reduce insulin sensitivity and the risk of diabetes.[13,14,18]
- Increase bone mass and decrease the risk of osteoporosis.[15]
- Reduce visceral abdominal fat and decrease the risk of metabolic syndrome.[16, 17, 18
- Improve circulation, blood pressure and the risk of cardiovascular disease.[18]
- Strengthening and safely enlarge the heart muscle, to improve its pumping efficiency and reduce the resting heart rate [20, 21, 22, 23]
Cardio Won’t Give You ‘The Look’
It should be said that the toned and defined look sought by most gym-goers is unattainable from simply doing aerobic exercise. As with all steady state type movements, the body quickly adapts and learns to burn less and less calories the more the exercise is continued and there are no profound changes in body fat or muscle mass as there is no stimulation intense enough to bring about an adaptation response in skeletal muscle. No matter how hard you may think that aerobics class may be or that session on the bike was- it can’t make profound changes in the way you look the way weight training can as there is no continued overload. Doing aerobics in conjunction with weight training doesn’t always give the best of both worlds either as the extra work can have a counterproductive effect on your weight loss efforts, since the added workload can lead to overtraining and consequently less results than you would get from resistance exercise alone.
Now it would be inaccurate to say that aerobic exercise is without merit- as such a statements fly in the face of countless studies that show very real benefits to doing it, but it may not be the only path to optimum health and fitness. I personally have not done any aerobic type exercise over the past 23 years and during that time I have been able to distinguish myself as a successful drug free bodybuilder, maintain year round body fat percentage of 6% all while sustaining an extremely high degree of cardiovascular conditioning. I have personally trained endurance athletes such as triathletes, marathon runners and distance cyclists and helped them increase their performance times using only three ten minute high intensity weight training a week and no cardio exercise whatsoever. Add to that twenty years of helping dozens of fitness models and bodybuilders get into contest winning shape using only high intensity training and proper dietary practices and the hundreds I have helped lose anywhere from 30 to as much as a 100 pounds- all without the use of aerobics or steady state exercises.
The appeal of cardio is easy to understand, as it requires little in terms of instruction and women for one tend to find it less intimidating than weight training. Cardio exercise are also easy for researchers to study, as creating controlled exercise protocols for groups is far less involved and costs far less to supervise and execute as compared to anaerobic type resistance training. Logically there are more aerobic exercise studies than anaerobic ones, which explains the initial bias towards cardio over resistance exercise in terms of weight loss and health benefits, but as more studies emerge using resistance training, we are learning that it can be equally beneficial and far less time consuming. There are also entire industries based on aerobic exercise- gyms, home exercise equipment, exercise classes and even the sneaker industry all invest heavily in promoting it, while there is very little in the way of promotion of weight training as dumbbells don’t sell gym memberships- cardio machines do. Nevertheless if you are serious about getting into great shape or looking for a more efficient way to improve your health and fitness, high intensity training might be a better fit for you over cardio. So get off the treadmill and pick up the weights if you really want ‘the look’ and don’t forget to watch what you eat as neither aerobic nor anaerobic exercise can negate the ill effects of an unhealthy diet.
The HARD Truth About Getting Ripped Naturally.
It's difficult to see actors, celebrities and fitness influencers routinely get bigger and much leaner within relatively short periods of time, but the reality is that for a natural athlete, getting leaner means getting smaller.
Without using drugs it's simply not possible to get huge while getting ripped. It just doesn't work that way and while women tend to have no problem getting smaller. Men tend to struggle with the fact that they look smaller in clothes when they lean out.
However, while you might look smaller in clothes, you'll look fantastic with clothes off when you lean out and as a natural athlete, it's important that we walk our own paths. And not be swayed by the unrealistic body transformations that are so ever present in both the regular media and social media.
So don't be afraid to get smaller and as always, Excelsior!!! #naturallyintense
#naturalbodybuilding #nosteroids #shredded #naturalathlete #fitnessgoals #bodytransformation #nodrugs #naturalbodybuildingtips #naturalbodybuilder #fitness #fitnesstips #nosteroids #naturalbodybuildingvideos #excelsior #fitover40 #personaltrainer #fatloss #fatlosstips
My Budget Home Gym Setup Recommendations
Anyone following along knows that I have a pretty impressive home gym setup, but as nice as it is to have all this equipment, the fact is that you don't need very much in order to make progress if you are training at home.
Which is why my number one recommendation is a pair of dumbbells. Maybe a barbell as well, but that's really all you need.
I trained for about a year during the lockdowns with just a pair of dumbbells and a barbell and was able to make tremendous progress, and to this day I universally recommend and provide dumbbells to my online training clients and they have made some great gains as well.
So if you are thinking about training at home, start small and keep it simple. Thanks as always for watching and as always, Excelsior!!! #naturallyintense
#homegymsetup #dumbbells #trainathome #trainingathome #naturalbodybuilding #naturalbodybuilder #naturalbodybuildingvideos #homegymlife #homegymequipment #homegymrat #homegymideas #homegym #personaltrainer
High Intensity Training- Negative Leg Extensions!
The negative, or eccentric, phase of any resistance movement creates the most micro trauma and thus stimulates the most growth and strength increases.
As such having someone pushing down in the lowering phase can REALLY up the intensity of your training.
This was my last set and my training partner and Naturally Intense Personal Training Senior Trainer @egcitrin is pushing down as I lower the weight and (and is it just me or is she pushing more and more as I go along?)
But I don't stop there.
On the 12th rep I execute an isometric hold for a count of 5 seconds with Erika actively pushing down before ending with nine punishing final reps!
I think I was sore for at least a full week after this but still training and hope you are too!
And as always, Excelsior!!! #naturallyintense
#naturalbodybuilding #naturalbodybuilder #highintensitytraining #highintensitytrainingtips #hometraining #homeworkout #fitover40 #naturalbodybuildingvideos #naturalbodybuildingtraining #naturalbodybuildingtips #naturalbodybuildingmotivation #legextensions #legday #legworkout #powertec #legdayworkout
Avoiding Injury As A Natural Athlete- Just Do This!
As a natural athlete, whether your goal is bodybuilding or body transformation, everything happens slowly and over very long stretches of time.
To that end, it is of the utmost importance that you prioritize not getting injured, as an injury can slow if not completely curtail your ability to realize your goals.
That being said, most people, when something hurts, just power through it, as there is this misplaced belief that there are some exercises that you need to do.
Squats, deadlifts, barbell bench presses and the like may be excellent exercises, but if it hurts, don't do it.
Or better yet, do something else to build yourself up to a point where you can do them, but there are times when some of those mainstay movements simply might not be for you.
Now for some, saying everyone can't squat or deadlift is heresy punishable by ridicule, but they won't be with you at the physical therapy sessions, and they will still be training while you are out.
If it hurts, don't do it, even if your favorite influencer swears it's a necessity. There are hundreds of alternatives, and your job is to find what doesn't hurt while recruiting the most muscular activation and sticking with it.
Do that and you'll save yourself a lot of pain and you'll realize your goals much faster as well. Stay safe while training and as always, Excelsior!!! #naturallyintense
#naturalbodybuilding #bodytransformation #nodrugs #weighttraining #listentoyourbody #avoidinginjury #naturalbodybuildingtips #naturalbodybuilder #fitness #fitnesstips #nosquats #injury #injuryprevention #trainsmart #sustainabletraining #nosteroids #naturalbodybuildingvideos #excelsior #highintensitytraining #fitover40 #personaltrainer #bodybuilding
Why Exercises Won't Get You A 6 Pack!
One of the most common questions I get asked is what exercises I do for my abs and my response of
"Absolutely none whatsoever" is often received with some sense of disbelief, but it's the honest truth.
I don't do any direct exercises for my abs and haven't since the mid to early 1990's because I already had a foundation from years of truly grueling ab work and having a six pack is directly proportional to what I eat, not what exercises I do.
My abs get plenty of work from the squats, rows, deadlifts and other compound movements that I do and I can prove, having not done crunches, leg raises, planks and any of that for the past 28 years or so that it's 100% diet.
If you want to have great abs, the exercise you need to master is walking away from the foods you shouldn't be eating.
My diet is and has been one of precision for a very long time, and it's what I eat and how I eat that allows me to always have a six pack, nothing else.
The good news is that everyone already has a six pack, you just have to get rid of the fat deposits above it for them to show, and if you put your mind to it, stay disciplined and avoid processed foods entirely, it can certainly happen.
So watch what you eat and focus on your diet if you really want that six pack and Excelsior!!! #naturallyintense
#sixpack #sixpackabs #6pack #6packabs #absmadeinthekitchen #everyonehasa6pack #abs #noabworkout #naturalbodybuilding #personaltrainer #drugfreebodybuilding #naturalbodybuildingtips #naturalbodybuildingmotivation #muscularity #naturalbodybuilder #timededicationsacrifice #excelsior #focusontheprocess #dothework #diet #abs
I Only Train Three Days a Week.
That's right.
Just three days a week with short high intensity training based workouts and it allowed me to compete successfully as a natural bodybuilder, and it's how I have trained and how my personal training clients have trained for the past 30 years.
The biggest problem in training is a lack of dedicated experimenting.
Everyone goes along with the training programs espoused by the most popular, without questioning the fact that the top figures in the fitness industry are all on steroids, and as such their methods may not always be best for natural athletes.
There are many reasons to consider low volume training but most importantly is that it allows for training sustainability.
Three days a week is far more doable long term than 4, 5, 6 or 7 days a week.
And I can tell you for a fact that it has been tested time and time again, and it works if you work it.
So give training less some consideration and as always, Excelsior!!! #naturallyintense
#train3xaweek #highintensityworkouts #naturalbodybuilder #trainlessexcelmore #trainsmart #sustainabletraining #competeatthehighestlevels #nosteroids #naturalbodybuilding #naturalbodybuildingvideos #naturalbodybuildingtips #excelsior #highintensitytraining
Lever Arm Presses 595 for 28 Reps!
High Intensity Home Training.
The (Titan Fitness) @betitanfit Lever Arm setup on my @roguefitness Monster Lite Rack and my @powertecfitness Utility Bench is a godsend in terms of adding variety to my home training.
It feels very much like a Hammer Strength Machine Press and the best part is that you can not only angle it to get the most out of the pectoral contraction, but that you can put the weight up at a point where it really feels heavy all to but the end of the movement.
For this movement I pyramided up to the most weight I could put on and decided just to go. No plan in terms of reps, just get to that point where it really starts to scorch and then keep going!
I don't think I ever got this many reps in before but I felt strong at the start and what I do know is that I was unnaturally sore for at least a full week afterwards!!!
Still training, hope you are too and Excelsior!!! #naturallyintense
#naturalbodybuilding #naturalbodybuilder #highintensitytraining #highintensitytrainingtips #roguefitness #betitanfit #UnleashYourTitan #ryourogue #hometraining #homeworkout #roguerack #fitover40 #naturalbodybuildingvideos #naturalbodybuildingtraining #naturalbodybuildingtips #naturalbodybuildingmotivation #leverarms #chestday #chestworkout #powertec
New Video: Why I Stopped Training In Public Gyms!
Click on my bio link to find out why!
In March 2020 after 31 years of training in gyms, I began training at home and have been training here ever since. Which is surprising for someone like me given how much I benefited from training in a gym environment, but over the years things have changed and not necessarily for the best.
Commercial gyms are a far cry from what they used to be and I began to feel over time that training in a public gym was starting to be detrimental to my overall progress.
Yes, it's more convenient to train at home.
Yes, there's no commute involved.
And yes, I can collapse on the floor after a workout and not have to move (which is really nice, by the way!!!)
But that's not the main reason why I stopped going to gyms and I can honestly say that I may never set foot in a commercial gym again.
Click on my bio link to see the full video and find out why!
Thanks as always for taking the time to look at my work and Excelsior!!! #naturallyintense
#gymlife #homeworkouts #fitness #trainathome #gymalternative #nomoregyms #gainsathome #naturalbodybuilding #naturalbodybuilder #naturalbodybuildingtips #fitover40 #naturalbodybuildingmotivation #homegym #hometraining #homegymlife #homegymsetup
Click To Get A Copy Of Kevin’s Free Ebook On The Role Of Exercise In Reducing Abdominal
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Aerobics & Strength Training- Does It Help Or Does It Hurt?
Featured everywhere from the Wall Street Journal to network TV, Kevin Richardson is the international fitness consultant for UNICEF, natural bodybuilding champion, creator of Naturally Intense High Intensity Personal Training and one of the top New York City personal trainers.
Do You Really Need Cardio – The Argument Against Aerobics References:
1. Beneficial effects of exercise: shifting the focus from body weight to other markers of health, N. King, M. Hopkins, P Caudwell, J. Stubbs, J. Blundell. The British Journal of Sports Medicine 2009
2. Impact of exercise intensity on body fatness and skeletal muscle metabolism. Tremblay, A. et al., Physical Activities Sciences Laboratory, Laval University, Quebec, Canada Metabolism.1994;
3. Bahr R (1992). “Excess postexercise oxygen consumption–magnitude, mechanisms and practical implications”. Acta Physiologica Scandinavica. Supplementum
4. Bahr R, Høstmark AT, Newsholme EA, Grønnerød O, Sejersted OM (September 1991). “Effect of exercise on recovery changes in plasma levels of FFA, glycerol, glucose and catecholamines”. Acta Physiologica Scandinavica
5. Bielinski R, Schutz Y, Jéquier E (July 1985). “Energy metabolism during the postexercise recovery in man”. The American Journal of Clinical Nutrition
7. High-intensity Interval Training: A Time-efficient Strategy for Health Promotion. Martin J. Gibala, PhD, Department of Kinesiology, McMaster University, Ontario, Canada Current Sports Medicine Reports 2007
8. Specificity of training adaptation: time for a rethink? John A. Hawley-J. Physiol. 2008
9. Singh NA, Clements KM, Fiatarone MA. A randomized controlled trial of progressive resistance training in depressed elders. Journal of Gerontology Medical Sciences
10. Doyne EJ, Ossip-Klein DJ, Bowman ED, Osborn KM, McDougall-Wilson IB, Neimeyer IB. Running Versus Weight Lifting in the Treatment of Depression. Journal of Consulting and Clinical Psychology.
11. Martinsen EW, Hoffart A, Solberg O. Comparing aerobic and non aerobic forms of exercise in the treatment of clinical depression: a randomized trial. Comprehensive Psychiatry
12. Singh NA, Stavrinos TM, Scarbeck Y, Galambos G, Liber C, Singh MA. A randomized controlled trial of high versus low intensity weight training versus general practitioner care for clinical depression in older adults. Journal of Gerontology: Medical Sciences
13. Pedersen BK, Saltin B: Evidence for prescribing exercise as therapy in chronic disease. Scand J Med Sci Sports 2006
14. Extremely short duration high intensity interval training substantially improves insulin action in young healthy males- John A Babraj , Niels BJ Vollaard , Cameron Keast, Fergus M Guppy, Greg Cottrell and James A Timmons
15. High-intensity resistance training and postmenopausal bone loss: a meta-analysis.Martyn-St James M, Carroll S. Osteoporos Int. 2006
16. Influence of exercise intensity on abdominal fat and adiponectin in elderly adults. Coker RH, Williams RH, Kortebein PM, Sullivan DH, Evans WJ.Metab Syndr Relat Disord. 2009
17. Effect of exercise training intensity on abdominal visceral fat and body composition. Irving BA, Davis CK, Brock DW, Weltman JY, Swift D, Barrett EJ, Gaesser GA, Weltman A.Med Sci Sports Exerc. 2008 Nov;40(11):1863-72.
18. Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism. Strasser B, Siebert U, Schobersberger W.Sports Med. 2010
19. Resistance training in the treatment of the metabolic syndrome: a systematic review and meta-analysis of the effect of resistance training on metabolic clustering in patients with abnormal glucose metabolism. Strasser B, Siebert U, Schobersberger W.Sports Med. 2010
20. Graf Ch., e.a.: Fachlexikon Sportmedizin: Bewegung, Fitness und Ernährung von A-Z, Deutscher Ärzteverlag, 2008, p. 209, ISBN 3769112237, here online
21. Reuter P.: Der grosse Reuter: Springer Universalwörterbuch Medizin, Pharmakologie und Zahnmedizin, Birkhäuser Verlang, 2005, p. 1300, ISBN 3540251049, here online
22 Woolston, Chris. “Ills & Conditions – Athletic Heart Syndrome”. CVS Caremark Health Information. 17 January 2007
