Cyclist have periods of time where they sprint and up hill as well. Either way breaking down a fiber and making the muscle sore or burn in a set does not = muscle growth
I agree. muscle soreness isn't needed for growth. cause you can cause the muscle to adapt to beyond being sore from a workout. once it adapts soreness doesn't exist.
causing the muscle to be fatigued whether it be from lifting weights or cycling be it high rep work or low rep work causes the muscle to need to strengthen and grow to meet the demands of the stimulus. the key is to put it under enough load to cause it to fatigue, and do it repeatedly. once it meets the demand of the stimulus growth will stop. it has adapted. then you can either increase the weight or the volume.
the key is to constantly force adaptation. that's where growth is. adaption equals growth. be it adaption to heavy weight, adaptation to increasing volume or ideally both because with every workout the body adapts to meet the demands your placing on it. once you stop placing demands on it, ie max out on weight you stop growing. how do you keep growing then? increase volume.
as you can see it has little to do with light or heavy and more up do with forcing the body to adapt. that's where the growth it.
as a whole this debate is a very slippery slope. so many variables come into play. natural or juicer will affect the debate massively to start with.