My father-in-law recently needed some help in the garden to prepare for a new concrete path. It involved shoveling a lot of heavy, wet, soil into a wheelbarrow, wheeling the wheelbarrow to the front garden, and then shoveling it from there into a skip.
As a software engineer, I’m really not used to this kind of work although it does happen occasionally. The really hard part was the shoveling. Pretty soon my shoulders and biceps were complaining, and I was beginning to worry about my back.
But, then I remembered Sifu explaining about core muscles. Basically, in any physical activity, if you can control your centre of gravity and arrange it so that the core (the muscles surrounding your body between your chest and your hips), or at least the large thigh muscles, are doing most of the work, then it is much easier. What you don’t want is leaning, or your shoulders or biceps moving the load.
There are many additional benefits of exercising and strengthening the core muscles. These muscles are not exercised that much in modern everyday life, especially if sitting for much of the day in an office. But, they are literally what is holding you up. Exercising them gives you more balance, static and dynamic stability, protects your spine and lower back from injury, helps your posture, which helps breathing, and many other benefits. They are used in almost every sport, when done correctly - running, tennis, cycling, football, kayaking, golf etc..
So, I changed my movements to using my thighs to lower and raise myself instead of leaning, and using my stomach to rotate, while my arms stayed pretty much static. Soon I was chugging through the wheelbarrow loads at twice my previous speed.. and found that I was noticeably less tired.
Interestingly, the only problems were holding on to the shovel and wheeling the wheelbarrow - these involved gripping the handles very tightly with my fingers, so there was no way my core could help. Since the fingers are actually driven by muscles in the forearms, they began seizing up and after a few hours I was having to stop wheeling halfway, and then resume, but the shoveling was still fine.
In the days following the work, I could feel that my back, waist, legs, shoulders and arms were completely unaffected. My forearms, however, were aching! This just meant to me that I had the correct technique, it was just that my hands could not keep up. The only way to help the hand grip, is dedicated gripping exercises.