Golf-Specific Isotonic vs. Isokinetic Training: Effects on Driving Performance

Several factors affect driving performance in golf. Initial ball velocity depends on club head velocity (speed and direction of the club face at impact), centeredness of club face on ball at impact, and club face orientation. Research also indicates that swing kinematics, power output, and sequence of action in the swing also affect overall driving performance. There is a lack of research into how different weight-training strategies can influence these above factors and driving performance.

Isotonic and isokinetic are two different types of weight training. Isotonic training is what you do when lifting a dumbbell or barbell for example. There is joint movement of variable speed against a constant external resistance. Isokinetic training on the other hand entails joint movement at constant speed against variable external resistance. The key difference between these two types of exercise is that isokinetic training allows for muscle contraction at near-maximal throughout the entire range of motion. Isotonic exercises typically get easier toward the end of the range of motion, once the joint is near its end-range and gravitational force across the remaining lever-arm gets reduced. If you’ve done a bicep curl or bench press with free weights in your life, you know that you’re not working nearly as hard toward the end of the motion. If you’ve seen a Nautilus weight machine at the gym where the cable wraps around a cam that tapers out like a nautilus seashell, this is an example of an isokinetic exercise. The variable torque provided by this tapered cam makes you exert with near-maximal contraction throughout the range of motion.

A 2017 study entitled “Effects of nine weeks isokinetic training on power, golf kinematics, and driver performance in pre-elite golfers,” published in the journal of BMC Sports Science, Medicine and Rehabilitation, sought to compare isotonic training to isokinetic training. The purpose of this study was to investigate if isokinetic rotational and lower body strength training for 9 weeks was more effective than isotonic strength training in improving rotational and lower body power, pelvis-thorax and shoulder kinematics, and driver performance among high-level golfers. Here is an overview of the study and its findings.

Methods

Twenty intercollegiate Swedish golfers (13 men and 7 women) all competing at a national level or higher participated in the study. All subjects had a handicap of −3.0 or better. All subjects were free of musculoskeletal injuries for the previous 12 months and had at least of 3 years of golf-specific strength training experience. There were no drop-outs in the study.

Participants chose which exercise group to join, either the isotonic training group or the isokinetic training group. 10 golfers (7 men, 3 women) joined the isotonic group, and 10 golfers (6 men, 4 women) joined the isokinetic group. The resistance training programs lasted 9 weeks, with a 1 week break in the middle to accommodate competition schedules. Both groups trained 3 times per week on average. Training involved free weight exercises, body weight exercises, and ballistic rotation exercises.

The isokinetic intervention:
For the isokinetic group, two isokinetic exercises replaced isotonic exercises, and isokinetic training was performed on average twice a week.  The two isokinetic exercises were a loaded isokinetic squat and an isokinetic standing rotation exercise. Both isokinetic exercises consisted of three sets of five repetitions. The loaded squat was performed with 25 kg barbell plus 10% of body weight for resistance, and the speed set at 0.5 m/s concentrically and 4 m/s eccentrically. The isokinetic rotation exercise was performed with 10% of body weight resistance, and at a set speed of 1 m/s concentrically and 4 m/s eccentrically.

Results

Data was collected just before and just after the 9 week training intervention. There were no baseline differences between the isotonic and isokinetic groups before the study began. Important outcomes in this study were both dominant side force, non-dominant side force, velocity, and power, all measured in the seated abdominal rotation test.

After 9 weeks of training, both groups increased their dominant side rotational power and rotational force. However, with isokinetic training, rotational power and force improved more compared to isotonic strength training. Neither group improved their club head speed, and both groups did increase their ball speed and carry distance. However isokinetic training appeared to have a greater effect on ball speed and carry distance compared to isotonic strength training.

Conclusion

The main findings of this study are that both isokinetic and isotonic strength training over a 9-week period had a moderate to large effect on improving rotational power, force, and velocity in pre-elite golfers. Even though isokinetic training did not increase club head speed, it did result in greater carry distance (by 7.6%) and higher ball speed and thus improved driver performance, when compared to isotonic training.

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Source:

Parker J, Lagerhem C, Hellström J, Olsson MC. Effects of nine weeks isokinetic training on power, golf kinematics, and driver performance in pre-elite golfers. BMC Sports Sci Med Rehabil. 2017;9(1):21.