"All generalizations are false, including this one." -Mark Twain
Each body has unique patterns and structures which must be taken into consideration when determining the most beneficial movement for the goal desired. I realize that the idea of structural differences like alignment of tissue, angle of tendon insertion or tendon length may seem too vague and not quite as easy to grasp as something like eye color, so let's do a simple test.
Bend your elbow at 90 degrees and flex your bicep. With your other hand, place a finger in the space between your bicep muscle and the crook of your elbow. Can you place more than one finger? If so, you probably cannot be a bodybuilder. This doesn't mean that you cannot lift and get larger muscles. It just means that your tendon is too long to achieve the appearance necessary for the bodybuilding look - the look where the muscles fill the space along the length of a bone usually requires less length of the tendon.
While you may not be interested in bodybuilding, this simple test should help to exemplify that there are physical differences in the structure of each of our bodies and those differences are the starting point for how our body will find easier ways to work as well as how the same exercises can yield very different results. Where tendon length might make a difference with appearance, the position where the tendon meets the bone can make a huge difference in the functional strength of the muscle. Just like levers, the position of the force (muscle) you apply relative to the fulcrum (joint) can drastically alter the amount of weight (dumbbell) you can move.
This is not new information (I think Mary Shelley even wrote about it), but since we are consistently fed the notion that we are all the same we tend to forget that we have differences. And in addition to things like tendon length and insertion angle, sometimes there are variances in the tissues themselves. An example of these differences, common differences that are not anomalies, is the psoas minor - a muscle which is estimated to be in about 50% of people. The specifics of this muscle are not relevant here, I am simply using it as an example that will hopefully disrupt some of the sameness thinking.
Certainly there are many similarities from one body to another, but the differences can be the reason why one person can get results from an exercise that another should not do. And why there are times when an exercise will actually work against your goal. The ideal care for a body is unique because every body is unique.
For many years the model has been to identify the ideal care for every body. The thinking seems to follow with the notion that we are all the same and as such we should be treated the same. This is simply not true. And now, finally, there is research that is being done that demonstrates that different people need different things. From diet and exercise to the care of your total health, that which is right for you is only right for you. I am not suggesting that norms and comparisons cannot provide a baseline. Our modern day ability to accumulate vast amounts of data can provide valuable insights, but it is just far too easy to give them greater value than they have.
Keeping an open mind and paying attention to your body's response is not easy, but it is the best way that I know to find what is best for you.
As always, let me know how I can help.