Do you plan to work for a business, or start your own?
If you plan to work for a business you should probably look at what they require, as if it is a legitimate business is should be in alignment with state requirements.
If you are planning to start your own you might want to look at this web site of the Maryland department of business and economic development:
The question of licensure is a hot topic in fitness (and in my own field of yoga) right now. This is a really interesting article on the topic:
Of course you aren’t asking if the state SHOULD be involved, but if they ARE. I do not believe they are.
There are rules if you are planning to offer nutritional services, and it is important to check your state’s web site for that. Those rules tend to be very specific.
It is also important to keep in mind that what the state requires is only the most minimum standard. There is also the question of industry standard. Anyone can put out a shingle, but the current industry standard is for a nationally recognized certification and/or degree in a related field. Typically not having one of those things is going to make it harder to get insurance, and not having insurance can leave one vulnerable if there is a problem on one’s watch… even if the problem is not the trainer’s fault.