I am 34 years old and have been training in a gym for 15 months. I find my progress is extremely slow.

For my age, are there specific recommendations?

There are not any specific things that I would change in a workout for someone who is 34 instead of 24 if they were in the same physical condition and had the same goals. Now, you're not going to be changing at the rate of an 18 year old! But your age is not at a level where your progress should be dramatically slowed. The one thing that might differ would be your recovery time and the importance of nutrition. As you get older you will need to be more conscious of making sure you get plenty of rest and nutrition. Then, as long as you are consistent with your training you will do awesome. I'm 34 and I can still outwork most 18 years olds! :)

If you are not having success towards your goals you might want to evaluate some things. Here are some questions:

Are you currently on a Fitrex Program?
Do you miss more than 1 workout every 2 weeks?
What is your nutrition like?
Do you take supplements (creatine, vitamins, protein)?
Are you doing cardio, if so, how much?
Are you in a high-stress job?
Are you getting 8 hours of sleep each night?

All of these questions should spark a thought process on everything from your training program to the things that enhance your recovery level and speed.

Check out out Nutrition Section for some great fundamentals on sound eating habits. I also encourage you to try one of my fitness programs. Every week is structured to allow for a quality progression in the volume and intensity of your exercise program. Some weeks are harder and some weeks are easier. They don't just beat you up every week with no changes in the amount of work you do. Supplements can also help if you don't always eat perfectly or if you are in a high stress job.

Stay positive and work hard!