How worried should I be about overexertion?

Question

I'm fairly young (about 30), and I ride my bike almost every day (commuting) and try to push myself, so I'm in decent shape. I also like to do longer rides, which involve riding steep roads up a nearby mountain. Even in my granny gear, the roads are steep and long enough to get my heart rate very high. I don't know exactly how high because I don't have a heart rate monitor, but it's high enough that I absolutely have to stop along the way.

Should I be concerned about overexertion? If so, are there any signs in particular I should look out for? I just want to make sure to avoid dangerous activity. If you're in good shape, is it safe to exert yourself as much as you're able to?

Answer 1

Based on your description, the only thing you should really worry about is dehydration (headache, dizziness, cramping), or heat related illnesses (heat stroke, heat cramps, hyperthermia). Your body will generally stop you from exerting yourself more than it is capable of. If your push right up to your limit, you may experience lightheadedness, greying vision, and nausea. Those symptoms are not related directly to your heart rate, but rather, to your body's inability to get oxygen to your brain and eyes (because it's being used elsewhere). If you're healthy, you can push yourself, but rest if you get some particularly strong signs to stop, unless you are okay puking at the side of the road.

Muscle strains are also a possibility when overexerting yourself, but a different kind of overexertion than you've described.

One rare condition that would begin to present itself 12-24 hours after very strenuous exercise with inadequate hydration is rhabdomyolysis (another description).

Answer 2

If you experience signs of dizziness, headaches, muscle aches, etc, then it is definitely a good time to take a break and let your body rest.

Also, you need to make sure you are receiving proper nutrition/hydration, eat something light before you exercise, as well as after.