DEAR DR. DONOHUE: I am a 29-year-old male distance runner. About a year and a half ago, I started having intense lower back pain. I saw a neurosurgeon about it recently. He ordered a CAT scan and myelogram. They showed a herniated disc. He's considering surgery. Could running have caused the problem? I also have pain in my hips and legs. What is the chance of an athlete returning to running after surgery? - J.W.

ANSWER: A ruptured (herniated) disc is not common at your age, but not unheard of. Many disc problems sit there, waiting to happen, and they can from something as simple as bending over to pick up a piece of paper. Even sneezing could bring on disk trouble.The cause of such problems involves the giving way of the dense material that forms the rim of the disc. When that happens, the soft inner jelly core protrudes and presses on spinal nerves. Since those nerves serve various areas, like hips and legs, pain there is a potential consequence along with the low back pain.

About 85 percent of those with disc problems have only one episode and don't need surgery. Rest and rehabilitation can work for them. Admittedly, your disc disturbance has taken a protracted course (lasting a year and a half). I wonder if you have had instructions in back care; for example, exercises to stretch and strengthen the back and abdominal muscles. Ask your physician about exercise, which you'll need eventually.

Can one return to running after disc surgery? Many do. If you are among the small number who cannot, you always can switch to activities like swimming or biking. If you send your address, I'll send you the backache material. Others can order by writing: Dr. Donohue/No.3, Box 830, Gibbstown, NJ 08027-9909, enclosing a long, stamped, self-addressed envelope and $2.

DEAR DR. DONOHUE: A little while ago you mentioned the number of calories burned playing golf. I can't imagine anyone endorsing this sport as any kind of a conditioning exercise. Golf seems to be no more intensive than taking a bath. - S.K.

ANSWER: Come on, S.K., don't be so hard on the golfers, even if it is not an aerobic exercise. To qualify for that, the activity has to get the large muscles, like those in the arms and legs, moving constantly for 20 minutes and the heart rate significantly above resting rate during that time. There aren't many casual activities in life that do that. However, golf is not without benefits.

Golf, played three times a week, 18 holes each, may just possibly lower the cholesterol. If not that, golf might help a person with poor leg circulation improve his lot by forcing new routes of blood supply. Furthermore, there's much to be said for the relaxation most derive from the game.

DEAR DR. DONOHUE: You've made problems for me. My wife tells me you frown on weightlifting for youngsters under puberty age. Why the dim view of this good activity? Get me off the hook, please. - P.A.

ANSWER: Your wife misinterpreted what I said. I concluded that lifting when done under supervision is OK for youngsters who have not reached puberty. Adults must be sure the youngster does not overdo and injure as yet immature bones.

- WANT TO GET INTO SHAPE? Dr. Donohue's booklet No. 12, "Introduction to Fitness" offers a fitness program anyone, regardless of age, can adapt. For a copy, send your request to Dr. Donohue/No. 12, P.O. Box 830, Gibbstown, NJ 08027-9909. Enclose a long, self-addressed, stamped envelope and $2.00.

- Dr. Donohue welcomes reader mail but regrets that, due to the tremendous volume received daily, he is unable to answer individual letters. Readers' questions are incorporated in his column whenever possible.