Introduction:
Golf biomechanical studies have looked at both kinematic (angles, velocities, sequences) and kinetic (ground reaction force, torque, impulse) variables in the golf swing. They have provided ample information related to swings of various clubs, lengths, shafts, swing types and other aspects of the golf game. These studies have helped coaches and players to understand the nuances of how skilled players move clubs differently than amateurs, how the inertial properties of a club (driver lengths, various clubs, single length club systems) alter movement mechanics, and even studies on how to teach/coach the game of golf.
Increasing speed has become a hallmark of success for players of all skill levels. Overspeed and overload training systems have been developed to help golfers train to enhance club speed, ball speed and carry distance. Previous research has shown increases and improvements in ground reaction force (kinetics) during a golf swing after training with the SuperSpeed golf training system. But to date, no study has been carried out to study the kinematic changes that occur because of speed training. Understanding these changes can help golfers to enhance speed training in ways that will help them maximize their speed gains.
Recent developments in Markerless motion capture technology have allowed for more easily collected data related to kinematic motion. One such software, Theia, is a system that utilizes video from multiple high-speed cameras to more accurately build a model without markers. This system has been used effectively in a variety of studies assessing human motion. The capacity of researchers is enhanced because of these new technologies and systems.
Understanding both the kinematic (angles, velocities, sequences) and kinetic (ground reaction force, torque, impulse) changes because of speed training can be beneficial for both golfers and those designing speed training systems. Additionally looking closely at the different inertial properties of a swing training implement (lengths, weights etc.) when compared to a driver may help understand the process of gaining speed even better.
The purpose of this study was to utilize a Markerless motion capture system to analyze both kinematic and kinetic changes of the golf swing because of speed training. Additionally, to investigate how and where the inertial properties of the swing training implement influence these same variables.
Methods:
16 participants started the study (4 did not complete the study, none of which were injuries). The average age of the participants was just over 40 years, and the average handicap was just under 12.
All participant testing was completed in the same laboratory conditions at Utah Valley University. Upon arrival to the lab, demographic questions were asked and answered, a warmup was completed and then golfers hit shots in the simulator to get further warmed up. Upon completion, the golfers hit a series of 10 driver shots. The first 5 shots were meant to be just “standard or stock” drivers, the next 2 they were instructed to build intensity and try to hit close to 100% of their max swing speed. After those 2 shots were hit, a very short rest period was given, and the last 3 shots were hit at max capacity while data was collected. The Theia 8-camera video-based system collected video images of players hitting on two Bertec force plates, while Trackman launch monitor data was collected for all shots.
Following pre testing, the players were instructed in the drills for the level 1 SuperSpeed protocol and were given the dynamic warm up and visuals related to these speed sessions. Players were instructed to perform the training 3x a week for 6-weeks. Upon completion of the 6-week training, golfers were brought back into the laboratory for the identical data collection.
In the pre-training session, golfers also had kinematics and kinetics of the three SuperSpeed 45 inch driver length speed training implements (light (255 g), medium (292 g), and heavy (336 g) and in the post-training session golfers had those same measurements for three 41.5 inch shorter length speed training implements (very light (206 g), medium (401 g), very heavy (506 g)). The driver length implements were used during training, while the shorter length ones were only swung at the post assessment.
Launch monitor data was compared pre and post, as were kinematic and kinetic changes during the last 3 driver swings. Additionally, the 6 speed training aids were compared to driver swings for kinematics and kinetics (the 3 driver length clubs to the pre driver swings and the 3 shorter length clubs to the post driver swings).
Results:
Average of the three max to max comparisons were made for the trackman variables for golfers comparing pre to post speed training. Club speed and ball speed increased significantly from pre to post (5% and 6% respectively) while carry distance had an increase of 20 yards (p=0.1). There were no differences in smash factor and the yards offline was the same pre and post speed training (Table 1).
|
|
Club Speed (MPH) |
Ball Speed (MPH) |
Carry (Yards) |
Smash |
Offline (Yards) |
|
Pre to Post Gain |
4.94 |
8.8 |
20 |
0.009 |
0.78 |
|
Pre to Post Gain % |
4.8 |
6.2 |
7.2 |
0.7 |
1 |
|
Ttest |
<0.01 |
0.03 |
0.1 |
0.62 |
0.92 |
No other trackman measured variables were changed because of the speed training. This included attack angle, club path, face angles etc. It is interesting to note that when comparing the 5 “stock” driver swing speeds to the 5 “max” swing speeds, golfers were able to produce 5 more mph of swing speed.
Kinetic changes from pre to post speed training included a significant increase in peak lead leg vertical force on the downswing (12%), and the peak lead leg lateral force on the downswing (17%). There were no alterations of sequences for the kinetics of the driver pre and post speed training.
Kinematic changes from pre to post training included significant increases of the peak pelvis velocity in the downswing (10%) and the peak trunk velocity in the downswing (6%). No changes in sequencing patterns were observed.
When comparing the speed training implements to the driver swings. The 3 clubs with similar lengths of the driver were the most like the driver mechanically. The lightest of the three driver length speed training clubs had a slight decrease in the lead leg lateral force on the downswing and a slight decrease of the A/P forces on the trail leg. The medium weighted driver length speed implement had only two differences, one being the decrease in lead leg lateral force on the downswing and a slight increase in peak arm velocity (15%). The heaviest of the driver length implements had the most differences, with four compared to the driver. A slight decrease in the lead leg lateral force, and trunk velocity. It did have slight improvements in the kinematic sequence with the relationship of the arm to the trunk and pelvis, with the arm peak velocity lagging behind a bit more compared to the driver swing.
The shorter swing training implements had more differences when compared to the driver swings. The lightest of that group had five differences. This included a decrease in the lead leg vertical and lateral forces on the downswing and a delay time of this peak (occurred closer to ball impact). Also, this club had an increased pelvis velocity in the backswing. The medium weighted shorter implement had eight differences compared to the driver. Decrease of the lead leg vertical and lateral forces on the downswing and delayed peaking of these forces. Also, a lateral peak trail leg lateral force on the backswing. A slight reduction in the peak trunk velocity in the downswing, increased downswing time and a slight increase in the arm velocity in the downswing. The heaviest of the shorter implements had differences including a decrease in the lead leg lateral force in the downswing and a lateral peak lead vertical force. Decrease in the pelvis and trunk velocities in the downswing, but an earlier peak of these velocities. A delayed peaking of the arm velocity (peaking closer to impact), an increased downswing time and a decreased swing tempo.
Discussion:
The findings of this study confirm previous studies showing that a 6-week SuperSpeed training protocol leads to increases in club speed, ball speed and distance while also increasing the forces on the lead leg during the downswing. Additionally, this study adds information that shows speed training also speeds up the rotational velocities of the pelvis and trunk during the downswing. Trackman data further suggests that there were no negative alterations to impact physics measured on trackman, particularly showing that smash factor and offline total yardage remained the same between the two testing conditions.
When comparing the swing training implements, those implements that were closer to the length and weight of a driver led to more similar kinematics and kinetics when compared with a driver, while the shorter and more varied weighted implements were more varied compared to a driver.
The consistency of the trackman measurements was a key piece of information in this study. Many players skeptical of speed training suggest that getting faster would only lead to altered swing paths, more mishits and more offline shots. But this study shows those variables are the same pre and post training. This study supports previous research showing that on course driver shots were more accurate after speed training than before and can help give players and coaches confidence that speed training with the SuperSpeed training system will not negatively alter impact physics and accuracy.
The continued findings of research related to speed training showing the increases of the forces in the downswing is encouraging. Previous studies have shown similar increases in lead leg forces in different populations. This is interesting to note in the context of seeing that the driver length implements swings didn’t alter these forces during swinging but did alter those forces post training in a driver. The level 1 SuperSpeed protocol contains regular swings (tested in this study) but also the step drill (not tested). The purpose of the step drill is to help golfers feel forces traveling to the lead leg in the downswing. The inclusion of these drills may partially explain why these forces do increase on the driver, while the overspeed training swings themselves do not elicit the same changes.
This study added the information that rotational velocities of the pelvis and trunk do increase because of speed training. The pelvis, trunk, arms and hands all help to pass force and energy out the body to the club and it is suspected that some of these would increase as a result of speed training. It is also important to recognize that sequences of the body did not get worse or improve in terms of timing of each segment’s peak velocities. Meaning similar movement sequences were seen pre and post training, just with an enhancement of the speeds of the movement. Further studies could be warranted to understand how to also increase arm and hand speed in addition to the benefits already seen with the pelvis and trunk.
Previous research has shown kinematic and kinetic changes with clubs of various weights and lengths. It was not surprising in this study that the shorter and more varied weight swing training implements did lead to differences in swing mechanics when compared with the driver, while those with similar lengths and weights had fewer differences when compared to the driver. The inertial properties of a swing training implement do alter mechanics of the swing during the speed training. If this leads to alterations in mechanical changes in the driver swing is not understood and a study should be carried out to understand this. This study did not aim to understand this question but does suggest that these studies should be carried out in the future.
In conclusion, training with the SuperSpeed training system leads to increases in CHS, ball speed and carry distance, while limiting changes in other trackman measured variables. Additionally, improvements in GRF variables of the lead leg and the velocities of the pelvis and trunk were seen following the speed training. Finally, the lengths and weights of the training implements do cause differences in swing mechanics in the acute setting. This study did not look at differences in swing mechanics over time when training with shorter length speed training implements. It did show that training with driver length implements leads to enhancements in magnitudes of variables related to speed and distance, without negatively affecting movement patterns while swinging a driver.
Dr. Tyler Standifird, Associate Professor of Biomechanics Utah Valley University