This is a blog, so I will keep it brief and avoid the technical backdrop, focusing instead on a simple point – you build strength through resistance.
Wherever/however how you want to develop your strength, you must think about getting your muscles to push or pull against a counterweight or force.
Think of a push-up or press-up. The counterweight is the floor. Likewise with squats.
Want to get your chest expanded? Then use a chest expander or a band of some sort, that applies the opposing force. When you run it’s the ground, when you swim, it’s the water, when you cycle, it’s the pedals.
We naturally, through common work and play, use certain muscle groups more than others. Sport, gardening, manual labour, tend to use the same muscle groups, in the legs/arms and shoulders.
How much these build and strengthen, depends on the regularity of use and the opposing force being applied.
If you decide you want to strengthen, then I think it is important to look on this in this simplified way.
In relation to health and fitness I suggest it is beneficial to take the most holistic, total body approach, you can contemplate.
You don’t want to be strong in parts, weak in others.
To progress we should learn and use as many resistance exercises we can, then to build our bodies, we do the necessary exercises regularly, and build the resistance.
Think of it like that – exercise the whole body to become stronger, building the resistance over time to build the strength, that builds the body.
Look at walls, floors, towels, ropes, bannisters, steps and stairs as equipment, all of which can aid you to develop ever greater opposing forces.
And, of course, you can invest in weights, resistance bands and other simple equipment to help you.
It is simple – this is how strength is developed, and you can do this at pretty much any age.
One final point – don’t forget nutrition! You help yourself more if you can eat for strength, which is probably more about what you don’t eat (so avoid sugary rubbish) than what you do.