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If a gym is a muscle-factory, how much does it produce?

Short answer: If a gym is used 100% efficiently, it can produce about 600 kg of muscle per week. More realistically, about 40 kg per week is normal for an average gym.

Long answer: First, let’s make some really generous theoretical assumptions and come up with an absolute maximum muscle gain rate. We’ll assume that the gym is being used at 100% capacity, 24 hours a day, with no congestion. Everyone knows exactly what their routine is, and their personal trainers have optimized it so no one is just waiting around.

This is a bit like fantasizing in traffic about every person stepping on the gas and going 80 mph while still bumper to bumper. In some theoretical sense it’s possible, but in the real world it would end catastrophically. Fortunately, I’m a theoretical physicist and it’s my calculation, so I make the rules.


Assuming an average gym has 100 pieces of weight training equipment, this means that 100 people can train at any given time at this gym. If we assume each of those people train for 1 hour a day, 7 days a week (fuck rest days), this works out to 2400 people on our muscle assembly line.

Various fitness websites claim that the most muscle mass that can be gained by a weight lifter is around 0.25 kg (0.55 lbs) per week [1]. At this rate, our 2400 lifters are collectively gaining mass at a rate of


(2400 lifters) (0.25 kg/lifter week) = 600 kg/week


This is almost exactly 1 gram/second, which is about the flow-rate out of a shitty water fountain. Except this water fountain pumps muscle.


Again, that was a pretty unrealistic estimate – no gym is getting used like this. More realistically, imagine that the gym is used at 50% capacity for 4 hours every evening, and each of those guys lifts for one hour every other day, so there are 400 unique lifters. Their muscle gain rate is also going to be less that 0.25 kg/week. That kind of rate is generally only possible for beginners, so all of our guys in the super efficient gym should be pretty slim to start. More experienced weightlifters tend to gain muscle at a lower rate, so if these 400 guys are avid athletes they’ll probably gain closer to 0.1 kg/week, so:


(400 lifters) (0.1 kg/lifter week) = 40 kg/week


This is similar to the flow rate of an even shittier water fountain.





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