I saw a pretty simple homework question here that asked how much work it takes to lift a 200 kg weight, and while the math for a basic answer is simple the weightlifter in me instead wanted to actually approach this question with a critical and pragmatic eye. There are many factors that one could consider to easily get a value different from the answer in a conservative field (for example: 1960 N for 1 meter).
I figure exact answers are obviously impossible. I want to instead see what methodologies can be used to start formalizing my upcoming reasoning (and also take this opportunity to correct any misconceptions I have) in hopes of closing in on a reasonable method to create an answer with more data. I also would love to see similar bio-mechanical studies and related material.
I mainly broke this problem up into two levels:
The human body is a collection of support structures (basically curved trusses), complex muscular tissue (non-linear springs with various attachment points), and connective tissue (constraints). Something I really could use clarification about here is the effect duration of the lift could have on the work exerted.
Our body metabolizes chemicals to generate store energy in tissue, then later break down that tissue into work and heat. Let's ignore the energy lost due to digestion and other secondary factors, and instead rate the efficiency of the human "engine" as a function of how much work he creates from the energy he expends doing the exercise.
Let's say we have a (large) man who lifts a bar 1 meter up from the earth when he does a deadlift, squat, or bench press.
How much energy does this body use to move 200kg doing each motion?
How much energy does this body expend to move 200kg doing each motion?