Bench Press Force, Power, and Energy
The concepts of force, power, and energy might be used interchangeably in everyday speech, but they mean different, thought related, things to physicists.
Take the bar and measure the vertical distance for a single lift _____ meters
Power Maximization
Load it with as much weight as you think you can lift about 10 reps rapidly. Do so and have someone time you.
Weight _____ lbs
Weight _____ newtons (multiply by 4.45)
Reps _____
Time _____ s
Energy ______joules (weight x distance x reps)
Power ______watts (energy/time)
Note that it is very difficult to achieve large amounts of power using the upper body alone.
Energy Maximization
Load the bar with as much weight as you think you can lift about 50 or 100 times, and then do as many reps as you can.
Weight ____ lbs
Weight ____ newtons (multiply by 4.45)
Reps ______
Energy ______joules (weight x distance x reps)
Energy ______kWh (divide by 3600000)
Value of energy in $ _____ (multiply by 0.11)
Force Maximization
We’ll skip the force (weight) maximization so that nobody destroys a shoulder, but the one rep max would be your maximum force.
Leg Workout
Have you ever wondered why you can lift so much more in a leg press versus a squat? Some of the difference is that they work different muscles and free weights tend to be harder to stabilize, but another reason is that the same amount of weight requires a different amount of force (strength).
We’ll use English units to keep the math simpler. These are pounds for force and feet for distance.
Squat
3/4 of your weight _____ lbs
Weight of bar and plates ____ lbs
Approximate total force on thighs ____ lbs (add the last two)
Jammin Squat
The “Jammin’ Squat” gives you what is called a “mechanical advantage”. It requires less force to lift weights than a regular squat.
Weight of apparatus _____ lbs
Weight of plates ____ lbs
Total weight of apparatus and plates _____ lbs
Horizontal distance between plates and pivot point ____ feet
Torque ______foot-pounds (force x distance)
Horizontal distance between shoulders and pivot point ____ feet
Force exerted on shoulders ______lbs (torque/distance)
3/4 of your weight ______lbs
Approximate total force on your thighs ______lbs (add the last two)
Leg Press
The leg press is for total weenies, but if you insist on doing such a lift, here is how to calculate what you’re really doing.
Weight of plates _____ lbs
¼ of your weight ______lbs
Approximate total weight ______lbs
Force exerted on thighs ______lbs (divide the last one by √2) / Way down the road in a gym far away
A young man was once heard to say
"I've repped high and I've repped low"
"No matter what I do my legs won’t grow"
He tried leg extension, leg curls and leg presses too
Trying to cheat these sissy workouts he'd do
From the corner of the gym where the big men train
Through a cloud of chalk and the midst of pain
Where the big iron rides high and threatens lives
Where the noise is made with big forty fives
A deep voice bellowed as he wrapped his knees
A very big man with legs like trees
Laughing as he snatched another plate from the stack
Chalking his hands and his monstrous back
Said, "Boy, stop lying and don't say you've forgotten"
"The trouble with you is you ain't been squattin"