Think of the activities that a lot of us consider the fundamental movements that will build fitness:
- Bench pressing
- Chin ups
These exercises are sometimes slated for being too one dimensional for the three dimensional movement demands of sport and life. Functional training was borne out of this 'problem'. People began creating exercises that looked more three dimensional. You can probably guess from my use of inverted commas that I don't this is that much of a problem.
The activities I have listed above have the net result of movement primarily in one dimension but on closer inspection, the movements are anything but one dimensional.
In running straight forwards, there is repetitive twisting and bending of the spine in all three planes.
In squatting, the knees of course bend and straighten in one plane due to their structure only allowing this. The hips above are a different story, as are the ankles below. The hips don't just flex and extend. They rotate out and bring the knees away from each other on the descent and do the opposite on the ascent.
All of these activities are similarly three dimensional, just to different extents. Taking the squat again, ideally the spine will only be moving through one dimension. With cycling, even when a cyclist is 'sat still', watch their spine wiggle in all three dimensions.
It turns out that when people don't use their three dimensional abilities to do these activities (any any others), their inefficient use of themselves leads to poor performance and quite often pain.
Where more obvious 3D movements (for example, a side lunge) will more directly target other dimensions (you will now often see me in the gym doing obviously 3D work that isn't commonly seen) and will facilitate your ability to work in them, this can be done through doing the linear movements in a better fashion too.
You just have to look at top sprinters and weightlifters - athletes who specialise in the 'one dimensional' movements - to see that they have managed to keep and expand their 3D capabilities.
3D movement is a human birthright and the basis of real athleticism.
Go and do 3D exercise AND don't be fooled that only 3D exercise will help you move and perform better in three dimensions. That is the myth of 3D exercise.
P.S. 3D exercise is a misnomer. These movements all involve time passing so, with time being considered the fourth dimension alongside our three spatial dimensions, it would be more accurately named 4D exercise. The physics geek inside me had to speak up!