Skiing is one of those black-hole sports that spine integrity cannot be predicted. You could ski all day on groomed slopes stopping before muscle fatigue and be just fine. However, if conditions worsen and you catch an edge, you fatigue prematurely, get hit by another individual or take an unexpected fall, the abnormal loading forces could injure the disc further.
Tennis is better but still carries risk due to the BLT component of the ground-stroke.
Dr. Corenman