My husband wants our American Pit Bull Terriers to bulk up too. Just for looks of course, and I'm thinking of getting mine into weight pull contests. Dog fighters are scum.
Do not use any heavy chains or weighted vests and do not start conditioning your dog until it is AT LEAST a year and a half old. These methods will harm your dog and they need time to grow before they start bulking up. Start with building up the dog's stamina with regular walks or jogs (without stamina you won't get the results you're looking for). Next get a weight pull harness and start by having him/her drag it a short distance. Slowly increase the distance and once that becomes easy you can increase the weight by a couple of pounds and start with short distance again. Don't have them pull more than 15 lbs for long distances. Some people increase the weight too quickly b/c they lack patience or don't feel like working that hard, but this could cause serious injury to your dog and they may just quit on you. Have fun! You're dog will love all the "play time" with you.
Do not use any heavy chains or weighted vests and do not start conditioning your dog until it is AT LEAST a year and a half old. These methods will harm your dog and they need time to grow before they start bulking up. Start with building up the dog's stamina with regular walks or jogs (without stamina you won't get the results you're looking for). Next get a weight pull harness and start by having him/her drag it a short distance. Slowly increase the distance and once that becomes easy you can increase the weight by a couple of pounds and start with short distance again. Don't have them pull more than 15 lbs for long distances. Some people increase the weight too quickly b/c they lack patience or don't feel like working that hard, but this could cause serious injury to your dog and they may just quit on you. Have fun! You're dog will love all the "play time" with you.