Yeah, 2 bottles in 40 minutes would make anyone's guts uneasy. You don't need to hydrate at all for efforts under an hour under most weather conditions. I'd drink a bottle of sports drink an hour or so ahead of time, long enough to be able to pee and then nothing until I got thirsty if it's a long ride, or after if it's just a test. Lots of aerobic hours will strengthen heart muscle. Beating on it maybe not so much. If you're doing an FTP test and this is what your question is about, use a cadence which gives you the best result. Everyone's different. I'm strongest at about 96 rpm. Many spin much faster, some slower. 175 HR isn't all that fast for someone only 49.
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