It is hard to choose between BOB (Body Opponent Bag) and the heavy bag. Perhaps you should choose. They both bring something unique to the table. Let’s see how he stacks up against the heavy bag.
With a traditional heavy bag, your goal is to develop power and endurance. The ways in which you can train on a heavy bag will vary into infinity. Ultimately, no matter how you train, you are using the bag to expand the attributes of power and endurance. With the BOB XL, your goals will shift into something a bit different.
The BOB XL’s main benefit is that it is anatomically correct. That has significant value for those that may be training for self-defense, but may have limited applications for those training in a MMA program. One reason for this is that the anatomically correct design provides for soft tissue targets such as the eyes and the throat. Again, hitting such targets with accuracy may prove helpful in a self-defense situation. In MMA, soft tissue targets are illegal. There is some value to hitting certain definitive points on the body with kicks.
Does this mean that BOB XL has no value for MMA training? Actually, there are benefits to using the BOB XL in the sense that you can hit specific knockout points such as the jaw, the liver, etc. You would not be able to hit such areas with accuracy on a heavy bag, because heavy bags are not designed to display such targets. So, those using the BOB XL in preparation for a MMA bout may wish to hit it with the intention of developing effective targeting.
So what is better? Well if you have to choose one, probably the heavy bag. There are more workouts that can be done on it, and it more versatile. BOB is pretty specific though. You can practice chokes on BOB and not on the heavy bag and get precision not possible on the heavy bag.
In a perfect world you’d use both. The technical training of BOB, combined with the strength training of the heavy bag would be perfect. So if you can swing it, cross-training on both is recommended.
Whatever you chose for your training tool, get out there and use it. Find a program you like, stick to it and you’ll see your skills improve from repetition and fitness gains. If you get to use both make one day a technique day, and the other cardio and power on the heavy bag. You’ll see your game become more fluid and your fitness improve.