Originally Posted by
wolfchild
All forms of cardio/endurance burn muscle especially if done in excess, running is even worse than cycling due to it's higher impact. That's why every cyclist who cares about their long term health should be lifting weights or doing some form of strength training.
I don't think that works out quite like that, especially individually. A lot of times people who cycle a lot have pretty big legs. Then there are the people who really focus on it and manage their weight to handle hills better and they may be thinner but in general I'd say cycling increases muscle mass, not the other way around. At least it's better than doing nothing in terms of muscle mass, as is all exercise. Even running is likely a net positive on muscle mass when compared to doing nothing. And running is also high impact so it's great for muscle and bone health.
As to doing some form of strength training, it's not about whether you're a cyclist or not. It applies to everyone and it has been long overlooked by mainstream health advice.