A careful and close study of the golf swing will reveal that it is mainly a rotary golf swing movement.
This is the reason why the most effective golf swing exercises are rotary in nature.
When using golf training aids like the weighted golf club, the rotary golf swing is practiced very effectively. This is a very golf-specific way of practicing and conditioning your muscles for the rotary nature of the golf swing. Using this aid, the golfer goes through the exact set of movements required in the rotary golf swing.
The inside approach is another golf aid that brings out the rotary nature of a golf swing. This device is quite useful for slicers and helps them deal with this problem. Actually this is basically a problem of ignoring the rotary nature of the golf swing and the result is the problem of slicing the golf ball instead of hitting it correctly.