The Trouble with Diet and Exercise Studies

The Trouble with Diet and Exercise Studies
A wiser man than myself once said there are "...lies, damned lies, and statistics.", add broadly interpreted conclusions to that statement and it applies to the world of fitness pretty well.  Don't get me wrong, I'm a firm believer in the role of both science and statistical analysis in the word of health and fitness; however, conclusions should be arrived at carefully.

So what's my beef with all these studies?  Let me break it down:

Population
 Typically, the survey populations in fitness studies are either high-level athletes or healthy, but completely untrained people.  While both these groups are certainly worth studying, the results you get will lead you to conclusions that may or may not apply to everyone else.  Untrained individuals will likely respond to almost any new stimulus added to a workout program.  Conversely, high level athletes will require more stimulus, are motivated, have a higher pain tolerance, a higher work capacity, and are more likely to be genetically gifted.

For example:  There was a study several months ago  that showed muscle growth in 15 "recreationally active" individuals lifting 30% of their on-rep max.  The problem with this study is twofold:
1.  15 people isn't exactly a massive sample size.
2.  I take "recreationally active" to mean healthy, but untrained which means they could probably look at weights and improve strength and muscle size.

Based on experience and observation I have never seen anyone gain a significant amount of muscle or strength lifting that low a percentage of their max.  To the credit of the researchers, the weights were lifted to failure which with training, would take a long time and just isn't that efficient way of training once you become somewhat conditioned.

Is this study completely without value?  If it's your conclusion that you should be training with 30% of your max then yes.  If your conclusion is that there is more than one way to skin a cat and that higher reps can sometimes be effective then no.  I think there is something to be said for training with higher repetitions, just not that high, for everybody, all the time.



Test Environment
Many exercise studies are conducted at universities under laboratory conditions which is exactly how no one trains ever.  Additionally, often studies are trying to isolate variables to prove or disprove their effectiveness which is incredibly difficult when studying human beings.

There have been a number of studies that show that stretching has no impact or even increases the likely hood of injury in runners.  The difficulty in drawing a conclusion with these studies is that there are so many variables it is impossible to isolate the cause.

Is lack flexibility causing a particular injury or is it caused by some other factor such as a muscle imbalance or the weight of the runner?

Are the subjects you're testing already injured or are they athletes who are almost never injured?  The latter may be unlikely to comply with anything new if what they've been doing has been working, while the former may just be more susceptible to injury.  If your an athlete who is a diligent stretcher and is never injured are you going to stop stretching to see whether you get injured or not?  How about if you never stretch and are never injured?  Are you going to start stretch just to see what happens?  In order to have a control you are asking people with routines to drastically alter them.

Using myself as an example (never a good idea) if I stretch my calves regularly, I feel that I have less problems with achilles tendinitis, which I'm susceptible to.  However, I've also had knee problems and when the physical therapist tests my flexibility, it's great.  When I stretch I notice no difference in knee problems.  What's the conclusion I can reach from this?  I think it is that there are many factors at play with running injuries, only one of which may be flexibility.

Too Good to Be True
We've all seen the "pop-science" studies that show that chocolate and wine are all good for you.  I don't deny that chocolate and wine are awesome, or that they can be good for you; what I do have a problem with is that the perception is then "if some chocolate and wine are good than a lot must be better!".  In other words people don't need to be told to have these things.  Dark chocolate is good in small amounts sure, but it's not exactly great in large amounts and for people that already eat a lot of chocolate and may need to cut back, it justifies their behavior.

The Science Trumps Common Sense and the Real World
Sometimes the science is real, but it's application to the real world is flawed.  The potatoes, rice, corn, and even fruits have gotten a bad rap because of the sugar content and/or the gylcemic index.  While there is some truth to that (these foods contain high levels of sugar and/or have a high glycemic index), are most people fat because they're eating too many fruits, rice, corn on the cob, and baked potatoes?  In individual cases maybe, but overall I have to say no.

An small ear of white corn contains 63 calories (albeit without butter) and 2 grams of fiber.  A large baked potato with skin (again without butter which would actually reduce the glycemic index) contains 278 calories, 8 grams of fiber, and 7.5grams of protein.  That's not bad.  If I had to place my finger on foods that are leading to obesity I would say processed white flower, baked goods, sugary drinks (juice included), candy, alcohol, fast foods, and other processed foods are the main culprits.  Eliminating whole foods like fruits, potatoes, or whole kernel corn from a diet when you're drinking alcohol, soda, juice, or coffee loaded with sugar everyday, is like worrying about a leaky faucet when your house is on fire.

Who Pays for It?
It's important to realize there are vested interests in producing studies with certain outcomes.  Much of the research on hydration is sponsored by sports drink companies who have an interest in keeping people drinking Gatorade instead of water.  Does this mean that the studies are wrong?  Not necessarily, but the studies deserve to be scrutinized.

What Does it All Mean?
Many of these studies do have value and are ultimately important in understanding the role diet and exercise and their impact on the body.  However, read the study and think about it critically.  Think of the body as an ecosystem with each piece potentially impacting the others and never forget the role that human behavior can play in the accuracy of data collection.