In 2007 a study (Sell, 2007) explored the strength, balance and flexibility characteristics of golfers compared to their handicap index. Testing included an assessment of strength (torso, shoulder, and hip), flexibility (torso, shoulder, and hip), and single-leg balance. The results concluded that those in the high golf skill category had significantly greater results across the board. Showing that being proficient in certain physical, functional characteristics was important in increased golfing performance. Of course, many people are naturally more naturally predisposed to certain physical components than others (I for example am quite strong, but have the flexibility of wood) however they also established that these characteristics were actually modifiable through golf-specific training programmes.
A resistance training programme (consisting of traditional strength exercises including squat, bench, lunges etc) can add significant length to driving distance without costing accuracy. ALL participants in this study by Doan (2006) increased clubhead speed after an 11-week training programme. This can be attributed to increased muscular force generating greater speed at impact. Additional velocity can then be gained with improvement in flexibility which assists the upper-torso rotational velocity, increasing clubhead speed and driving distance.
These findings were not limited to age and showed that increases in physical components at any age had a direct effect on club head speed and driving distance (Thompson,2007)
There are many more studies that continue in this manner. Of course, most of the research has been carried out on male participants, but there is no evidence that it should be any different in female performance. Those that did include women in their studies (Torres-Ronda,2001; Kim, 2010) found equally consistent correlations.
The evidence therefore is substantial. A golf-fitness program is one of the best ways of improving your golf.