titleistperformance.com has a terrific workout regimen to improve the golf swing. In the case of leg strength you may consider digitalrunning.com. The speed of the turn and the torque which is driven by your toes, feet, legs, hips, body, wrists is what is going to improve your clubhead speed. Digital running has a few exercises that may surprise you, as they focus on one leg at a time, and stability. It's hard for me and I consider myself in shape. I have been working the torque, stability, flexibility and strength into my workout week.
torque, stability, flexibility and strength.
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In an interview with Rory, he said that he was one side to dominant in strength and he does a ton of single arm, and single leg workouts, i think this is important. Try a bicep curl with your dominant hand versus your non dominant hand, you'd be surprised at the difference.