I started cycling being a person made almost entirely of fast-twitch muscle. Big gears and mashing didn't cause my muscles to burn (eventually, it might cause complete muscle fatigue--or joint problems in some people). The more I worked on spinning fast, the more it burned. But I persisted, and it got a lot easier. So I'd say that the burning doesn't necessarily have a correlation to your gear choice. That probably depends on how your body likes to work (your "type") versus your training history.