A coach should tailor a training program to you, taking into account your strengths and weaknesses, and not just plug numbers into a formula. He/she should provide feedback, both constructive and positive. :-)

Lowell expects me to follow his plan and advice to the best of my ability, allowing, of course, for some flexibility based on schedule, illness, injury, etc. He expects me to trust his judgment, but is open to discussion if I have questions or think the plan is unreasonable.

We communicate almost exclusively by email, usually once a week. Lowell gives me a plan in four- to six-week blocks. Some people may need more interaction, but this works for me.

Obviously, having input from someone with expertise is a huge thing, but you can find lots of people out there who are willing to give advice. The advantage to having a personal coach is the fact that the advice is made to fit YOU. Keep in mind that it may take some time for your coach to learn what works best for you. Lowell and I have been working together for four years, and he knows by now how to filter through the whining and figure out just how hard he can push me without overdoing it. For me, the best things about having a coach are the accountability factor and the structure.

I honestly cannot think of any disadvantages to having a coach, as long as you find the right one. Talk to him/her ahead of time, and find out exactly what each of your expectations are of the other. Discuss your personal preferences about interaction (frequency, method, etc.) and make sure you are both on the same page. I think the biggest thing, though, is trust, and that has to go both ways. Just as you trust him/her to give you sound advice, your coach will trust you to follow the plan.

Good luck in your quest...I hope this helps!