One body, three layers
In the last hour of a long run, ride or swim, you can see what the body is missing. The hips start to drop. The shoulders creep up. Your heart and lungs may still have plenty left. The body carrying them is coming apart, and every minute costs a little more than the one before.
When researchers filmed 179 runners at 8 km and again at 40 km of a marathon, every one of them had changed. Each foot stayed on the ground about 13 percent longer, and the hip reached about 28 percent less far behind them. The fastest runners held their knees best, and the researchers put that down to muscle: they could keep producing force for longer.
That looks like a problem of endurance alone. It is all three layers giving way at once.
01
Three layers, one body.
Endurance is a game of efficiency, and efficiency is built in layers that stack like a pyramid. Mobility is the base, strength is the middle and endurance is the peak. The peak can only rise as high as the layers under it allow.
Mobility is the base because a body that has to fight itself just to move cannot be efficient. A hip that will not open shortens every stride. A shoulder that will not reach shortens every swim stroke. The movement still happens, but something else has to bend to make room for it.
Strength is how you apply force to move yourself. A mobile body without strength just leaks energy, and that kills efficiency. Being able to reach a position is not enough. If the muscles around a joint cannot hold it, the knee falls inward, the pelvis drops and the trunk sways. Each of those wastes a little of the effort that should have moved you forward.
Endurance sits on top. It is your ability to keep moving hour after hour, and to hold the quality of that movement while you tire. It is the layer that takes you out into the world, and the two layers under it are what keep you able to go.
02
Life used to build all three.
For most of human history, nobody trained these separately. The same day that kept people walking for hours also had them squatting, climbing, lifting and carrying. The body got its range, its strength and its engine from one life, and it got them together.
Even rest used to ask something of the body. Hadza hunter-gatherers in Tanzania spend about ten hours a day not walking, much like office workers. But much of that time they squat or kneel, and those positions keep the leg muscles working in a way a chair never does.
Modern life took them away together too. The chair took the range. The machines took the lifting. The car and the lift took the hours on foot. But many people who start training put back only one of them: they run, or they lift, or they stretch.
03
Lose one, and the others pay.
Picture three athletes. The first only does endurance. The engine grows every year, but the body moves through the same narrow range for hours, and nothing asks it for force. The second only lifts. Strong and solid, and out of breath at the top of a long flight of stairs. The third only stretches. Wonderfully supple, with nothing to hold that range when it matters.
Each of them is fit in one way and fragile in the others. Each is training part of a human.
The evidence points the same way. A review of studies following more than half a million adults found that people who did both strength and aerobic exercise were about 40 percent less likely to die over the years they were followed than people who did neither. Nobody has yet followed people who practise all three layers. But two together already beat one.
The layers are not built in turns. You do not finish mobility, move on to strength, and only then start to run, ride or swim. You build all three alongside each other, from the first week, and the peak rises as the layers under it grow.
04
Practise all three.
Each layer has its own practice. Yoga builds the base: the range to get into a position and still be strong once you are there. Kettlebells build the middle: whole-body strength that moves you, and holds you together when you are tired. Running, swimming and cycling build the peak: the engine that keeps you going for as long as you need it.
None of them exists to serve another. Each one is real training, and each one is a part of you that would otherwise go missing.
What this means for you
The human body can sink into a deep squat, lift a heavy load and keep moving for hours. Lose one of these layers and you lose part of what makes a human so magnificent.
Practise all three. Every week, make room for some mobility, some strength and your endurance, and let them grow together.
Sources
- Chan-Roper et al. 2012. Journal of Sports Science and Medicine 11:77-82. Kinematic changes during a marathon for fast and slow runners.
- Raichlen et al. 2020. Proceedings of the National Academy of Sciences 117:7115-7121. Sitting, squatting and the evolutionary biology of human inactivity.
- Momma et al. 2022. British Journal of Sports Medicine 56:755-763. Muscle-strengthening activities and mortality, a meta-analysis.