Exercise: Can There Be Too Much Of A Good Thing? Reply

In recent years researchers have developed a more complicated view of the relationship of health and exercise. Although observational studies have consistently shown that some physical activity is better than none, studies that have drilled deeper into the data suggest that these health benefits may be curtailed in people who exercise very frequently or very intensely. Now two new studies from Europe, published in the journal Heart, offer new support for these observations.

Click here to read the full post on Forbes.

 

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Large NIH Trial Finds No Cardiovascular Benefits For Weight Loss And Exercise In Type 2 Diabetics 1

A large NIH-sponsored trial has found that an intensive lifestyle intervention was no better than standard care in reducing cardiovascular events in people with type 2 diabetes. The results of the Look AHEAD trial were presented today at the American Diabetes Association meeting and published simultaneously in the New England Journal of Medicine.

5,145 people with type 2 diabetes were randomized to either an intensive lifestyle intervention, focusing on weight loss through a low-calorie diet and increased exercise, or conventional diabetes care. Trial investigators had planned to run the study for as long as 13.5 years, in the hope of finding a significant difference in the rate of major cardiovascular events (death from cardiovascular causes, nonfatal MI, nonfatal stroke, or hospitalization for angina). However, after 9.6 years of followup the data and safety monitoring board performed an analysis and recommended that the trial be stopped for futility.

Click here to read the full story on Forbes.

Small Study Suggests Statins May Blunt Benefits Of Exercise 1

A small study is raising big questions about whether statins may blunt the beneficial effects of exercise. The study has been published online in the Journal of the American College of Cardiology and was the subject of a New York Times blog today.

The authors concluded: “Given the strong independent cardio-protective effects of increasing cardiorespiratory fitness or lowering LDL, the benefits and risks of each should be carefully considered when choosing treatment modalities.”

Click here to read the full story on Forbes.

 

John Thyfault

 

Exercise And The Limitations Of Observational Studies 8

Last week I wrote twice about exercise. Strictly speaking, both stories were complete lies.

The first story was about a study published in the Lancet which analyzed data from more than 10,000 patients at 2 VA Medical Centers and found that patients with high fitness levels were less likely to die than patients with low fitness levels. The pattern held true whether patients were taking statins or not taking statins. The researchers concluded:

“Statin treatment and increased fitness are independently associated with low mortality among dyslipidaemic individuals. The combination of statin treatment and increased fitness resulted in substantially lower mortality risk than either alone, reinforcing the importance of physical activity for individuals with dyslipidaemia.”

Look carefully at that. The association of fitness and low mortality leads to the recommendation about “the importance of physical activity.” An accompanying editorial went further, recommending that “prescription of physical activity should be placed on a par with drug prescription.” Widespread media coverage of the study followed suit, with nearly all reports emphasizing the positive effects of exercise.

So what’s wrong here? It almost seems churlish to insist on the point, but of course the study (like all other observational studies) didn’t– couldn’t– actually say anything about the real effect of exercise on health. It seems reasonable to assume that more exercise leads to increased fitness leads to improved health. That’s what we all probably think and believe. It’s common wisdom. But it’s not entirely unreasonable to suppose that healthy people are much more likely to exercise, in effect reversing the cause and effect. And of course there may be other confounding factors that cloud the simple equation of exercise and health.

There’s more: even if you could prove that more exercise leads to better health that wouldn’t lead to an automatic conclusion that doctors should recommend exercise as much as drugs. First you would need to prove that an exercise prescription is just as effective as a drug prescription. It’s hard enough to get people to take inexpensive, life-saving drugs once a day. Is there any reason to think we can get any kind of effective level of compliance with an exercise prescription?

The other exercise story from last week had a much different conclusion. Editorialists in Heart concluded that although most exercise is good for you, too much exercise can actually be harmful. They may well be right, but there’s never been– and there almost certainly never will be– a good, properly designed randomized trial that could prove this theory. It’s entirely possible (in fact, almost certain) that people attracted to extreme endurance sports are different in many ways from the rest of us, and it’s quite plausible that some of those differences may have significant effects on health. Confounded again.

The last thing I want to do is trash exercise. I’m a big supporter of it. But these standards shouldn’t be compromised. So what is the proper way to report this kind of study? Here’s a brief, completely responsible version of the story (written by Kelly Young for Physician’s First Watch):
Click to continue reading…

The Dangers Of Going Too Fast 5

Updated– According to an editorial published online in the BMJ journal Heart, running too hard, too fast, and for too long can be dangerous. The same holds true in publishing. The editorial was hastily released ahead of its scheduled publication time after portions of it were quoted in Wall Street Journal article on the dangers of endurance sports. A BMJ representative told me that Heart had not yet found out how the WSJ article gained early access to the editorial, although in the article it appears that the Heart editorialists spoke at length with the WSJ reporter.

In the editorial, cardiologists James O’Keefe and Carl Lavie marshall the evidence suggesting that “extreme endurance exercise may exact a toll on cardiovascular (CV) health.” The authors acknowledge that runners have only a very small risk of dying during a marathon, but “chronic extreme exercise” can induce “adverse structural and electrical remodeling, which offsets some of the CV benefits and longevity improvements conferred by moderate physical activity.”

The authors cite data showing that “improvements from unfit to moderately fit confer dramatic reductions in morbidity and mortality” but that “fitness levels above 12 metabolic equivalents do not seem to translate into additional gains in CV health and longevity.” The authors posit a U-curve, with “couch loungers” on one side and “extreme exercise aficionados” on the other side. They recommend moderate exercise as “the safe and comfortable zone at the bottom of the U curve, which, they say, is the sweet spot for most people. They conclude with a “take home message” recommending that most people limit vigorous exercise to 30-50 minutes per day.

In the WSJ article both O’Keefe and Lavie, former elite athletes with years of intense training, discuss their current moderate exercise regimens. The article also includes an old quote from Kenneth Cooper, the sports physician who helped launch the original aerobics movement: “If you are running more than 15 miles a week, you are doing it for some reason other than health.”

Update– I asked Heart editor Adam Timmis to comment on this episode and whether he thought the Ingelfinger rule (which forbids prepublication publicity about a forthcoming paper) applied in this case. Here is the response I received:

“Embargo breaks are always regrettable, of course. But while the Ingelfinger rule is a worthy one, to apply it in this case would be like taking a mallet to a walnut.

The article in question was a review article- albeit in editorial format-not original research. And there is little or nothing in the piece that is not already in the public domain. Therefore, we think that it would be excessive to withdraw it from publication.”

Statins and Exercise, Independently Beneficial, Even Better In Combination 2

It’s no secret that statins and exercise are good for people with cholesterol problems. Now a new study published in the Lancet offers fresh evidence that the two appear to be independently beneficial, and that adding the two together may result in greater benefits than either alone.

US researchers analyzed data from 10,043 people with dyslipidemia treated at 2 Veterans Affairs Medical Centers. Participants were followed for a median of 10 years, during which time nearly a quarter of them died. After adjusting for baseline characteristics and other risk factors, mortality was separately and independently reduced by statins and by fitness level, with the greatest benefit found in the group of patients who were taking statins and were highly fit (>9 MET). The researchers further reported that only a moderate and achievable amount of exercise produced an effect similar to that of statins in people not taking statins. “Improved fitness,” they wrote, “is an attractive adjunct treatment to statins or an alternative when statins cannot be taken.”

“The fitness necessary to attain protection that is much the same or greater than that achieved by statin treatment in unfit individuals is moderate and feasible for many middle-aged and older adults through moderate intensity physical activity such as walking, gardening, and gym classes,” said lead researcher Peter Kokkinos, in a Lancet press release.

In an accompanying editorial, Pedro Hallal and I-Min Lee write that “the undervaluation of physical activity in clinical practice” is “unacceptable.” “Prescription of physical activity should be placed on a par with drug prescription.”

Photo by T-Rex Runner (click on the the picture for more background)

Click here to read the Lancet press release…

Guest Post: The BMJ’s Amazing Shock and Awe Assault on Sport Drink Science 3

Editor’s Note: The following guest post by Yoni Freedhoff is reprinted with permission from his blog Weighty Matters. Dr. Freedhoff is an assistant professor at the University of Ottawa the and founder of Ottawa’s Bariatric Medical Institute.

The BMJ‘s Amazing Shock and Awe Assault on Sport Drink Science

by Yoni Freedhoff

wow.

Wow, WOw, WOW!

What words would you use to describe a situation where one of the world’s most prominent medical journal publishes, not just one article critical of a specific category of food, but seven such articles, and where those articles come to the conclusion that the food is being marketing on the basis of food industry funded hype and collusion?

I’d use the words, “Thank You”!

You’ll definitely hear about it in the news today as the British Medical Journal has 7 incendiary pieces that are highly critical of sport and energy drinks, their Big Food parents and the researchers that are conflicted by them.

The first piece (Research: The evidence underpinning sports performance products: a systematic assessment) has researchers analyzing sport drink advertising and identifying an astonishing 431 performance enhancing claims for 104 different products. Those claims were “backed up” by references made on the products’ websites to 146 references. Of those 146, the authors could only actually find half of them, and of that half:

84% were judged to be at high risk of bias“,

while only 3 were deemed to be of high quality and of low risk of bias. Ultimately the authors not surprisingly concluded that:

The current evidence is not of sufficient quality to inform the public about the benefits and harms of sports products

Click to continue reading…

This Week In Medicine: Stop Exercising and Eat Chocolate! 5

It’s been a terrific few days of medical news for lazy people and chocoholics.

First, a study in PLoS One provided ammunition to the exercise-averse crowd by claiming that exercise can actually be bad for some healthy people. As an added bonus, a story about the study was carried on the front page of the New York Times.

Less than a day later, in a moment that will be long treasured by chocoholics, a study in BMJ calculated that people with metabolic syndrome could reduce their risk of serious cardiovascular events like heart attacks and strokes by eating dar chocolate every day.

Let’s take a quick look at each study:

The exercise study used data from 1,687 people who participated in one of six different exercise studies and found that a surprisingly large percentage of people had a significant adverse change in one of several important risk factors:
Click to continue reading…