How do sports fitness trainers treat lumbar sciatica?

Varies. There is probably some variation among trainers, but most would likely work on aerobic fitness, flexibility and core strengthening exercises. She or he may also adjust the program depending on how acute and severe the pain is, your age, your fitness, your tolerance to new exercise.
Teach you Exercises. Typically core strengthening exercises are the best to help relieve pressure and forces in the spine. I would suspect that the athletic trainer will work on these with you. Unlikely besides exercises and stretching will they be able to offer more. Sometimes this is all you need.
Traction + Core. Most physical therapists and fitness trainers will use lumbar traction, stretching, and strengthening of the core muscles (in the back and abdominal regions) to help improve the symptoms of lumbar sciatica.

Related Questions

How would sports fitness trainers treat lumbar sciatica, the pain that radiates from hip to toe?

Stretching . Is one effective way. Read more...
Not recommended. Causes of sciatica should be evaluated by a sports medicine professsional in order to properly direct treatment. Pain may be coming from a herniated disk, arthritis in the neural foramina (opening in the bony spine that the sciatic nerve exits in the low back), or other areas. Physical therapy, medication, injections may be warranted depending on the severity. Read more...
Core Exercises. Typically core strengthening exercises are the best to help relieve pressure and forces in the spine. I would suspect that the athletic trainer will work on these with you. Unlikely besides exercises and stretching will they be able to offer more. Sometimes this is all you need. Read more...