This lens is likely not going to work for you for close up gymnastics. I would probably recommend a 28-300mm F4.0/5.6 nikon lens. I have this lens and am quite happy with it. There is also a 70-300 mm lens by Sigma with nikon mount for approx $200 or lens. Both these lenses should work under ambient light but not in semi darkness like after 4pm without flash. If you want to take pictures in lower light you can increase your ISO settings or get a F2.8 prime zoom for 70-200mm
Thanks for the info. I have the 70-200 2.8 lens, and it works great, but some of the meets I am to close for even the 70 setting. What about the 24-70 2.8?