It’s worth noting that muscle is not all the same. If you’re just into bodybuilding then sure, proximity to failure is what matters. For athletics though, there still seems to be a big impact in the rep range you work in.

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d-us-vb 5 hours ago | parent [-]

This. Muscles can be optimized for volume/endurance or power, or some balance between them. Taking legs as an example: Powerlifters obviously go for pure power, whereas runners need a bit of power but mostly endurance, whereas cyclists need more power than runners but more endurance than powerlifters.

All of these benefit from weight training, but depending on the sport, the programming will be very different.

	▲	allan_s 4 hours ago \| parent [-]
		I think I know where they're coming from as I used to have a similar wrong model. I thought strength = more muscle cells and endurance = just better heart/lungs to deliver oxygen and clear waste like CO2 and lactic acid. Turns out muscle fibers mostly grow bigger rather than more numerous, and there are different fiber types (slow-twitch vs fast-twitch) that adapt based on how you train. So for the same muscle, an Ironman runner and a guy doing heavy low-rep squats will develop different fiber characteristics: you can't fully max out both. I'm simplifying, but learning this changed a lot about how I understand exercise at the biological level.