Imagine for a second (and it’s not too hard to do), two bodybuilders posing down in a mirror. Let’s say they’re comparing their biceps and let’s face it, who hasn’t flexed their bicep at some point and checked out what this lumpy muscle at the forefront of their arm has to offer? I’ve done it and you’ve probably done it too. For most people it is an exciting feeling to find a significant bubble to show off to their friends or to just take their own personal satisfaction from. It’s a great indicator of increased strength and a change in body composition but does it tell us anything about health? Now, let’s go back to our bodybuilders comparing their biceps. Who wins the contest? Well, it depends on the contest. Let’s compare a few different contests:
1. Biggest bicep
2. Best physique
3. Strongest man
4. Healthiest man
1. The contest for the biggest bicep is easy to decide. We grab a tape measure and we measure the circumference of the upper arm at the midpoint of the humerus. Even this has it’s flaws as it is virtually impossible for us, without the use of an MRI or other medical device, to measure the size of the bicep in isolation. We will also be measuring a number of other upper arm muscles.
2. The contest for best physique has a long history now and this is how bodybuilding contests are judged. They use a combination of size, symmetry and definition to determine the best looking physique but this essentially comes down to the eye of the judge.
3. Cross-sectional area is a very strong determinant of the strength of a muscle, however the strength of a muscle is not just determined by it’s size but by numerous physiological markers that make that muscle function effectively. So being big correlates with strength but it is not a perfect predictor. Take a look at most of the greatest athletes in any strength-based sport and you will see that while size is important it is not the entire answer. Surprisingly, size can actually have a negative effect on performance for most athletes. It’s simple physics. If you take two sprinters of the same strength and one is 1kg lighter than the other, the lighter runner will run faster if all other factors are equal. So if we want muscle size to be functional we need it to be a by-product of an improved muscle function so we can move that extra weight and perform better than before. Now, it’s getting complicated, isn’t it?
4. Unfortunately there is really nothing in this bicep comparison that will tell us who the healthiest man is. We can get a good prediction of who is stronger based on the muscle size but strength is only one component of our health and fitness. It tells us very little about the quality of life we lead and it tells us even less about our predicted longevity.
Taking the example of our two bodybuilding friends again I want you to imagine a vivid picture of them both posing in front of the mirror, trying to compare and outpose each other. Take a second to make this picture vivid in your mind. Now get both of your bodybuilding buddies to reach into the back pocket of their training shorts and pull out a piece of paper. Picture them taking a seat at a desk and now take a look at what is on that piece of paper. On the paper is a series of medical tests from their GP and we now begin a new contest as they both compete against each other for the best blood markers that predict morbidity and mortality. 
Can you imagine this as a metaphor for society. Imagine if we were just as excited and inspired by our level of disease risk that we would want to show it off to our friends just as we might do if we had big biceps?! The effect that this would have on the daily activities of millions of people is inestimable. So what is most important to you?