One of golf's most common swing flaws is failing to maintain the posture created at address. Many amateurs rise out of their stance as they swing the club down from the top, and this causes them to make poor contact with the ball. Fat and thin shots are a typical result.
Golf instructors will often try to fix this issue with various drills that help keep students from changing their posture when they swing down and through the impact zone. An example would be to hold a golf shaft just over a student's head and have the student make swings trying not to bump the shaft. Another would be to the student maintain the knee flex created at address.
Both are effective, and often a golfer with this stand-up problem will immediately start hitting solid shots after using these drills. The teacher and student shake hands and go on their merry ways. Problem solved, right?
It's easy to correct this problem for a swing or two, or even half a round. But without strong, flexible hamstrings (the muscles on the back of your thighs), the problem will come back; especially after fatigue sets in. Your hamstrings help support the body while you swing. Wherever you are right now, get into your address posture and then feel the back of your legs. If you can't feel your hamstring muscles working to hold that posture, you're probably going to struggle to hit the ball solidly.
So how can you fix those fats and thins in the gym? See me demonstrate a stretch and a strengthening exercise provided by well-known trainer Mark Verstegen (@teamexos) below.
Ron Kaspriske is the fitness editor of Golf Digest.