motordevelopment-blog1

[motordevelopment-blog1]

Introduction

The task being analyzed is a golf swing in four different developmental age groups. Saliah (6-years-old), Jack (12-years-old), Luca (18-years-old) and Ann (60-years-old) were our participants for this task. A golf swing consists of six consecutive phases: set-up, backswing, transition, downswing, contact and follow-through. An ideal set up consists of a flat strong back, trunk flexed to 45 degrees with forearms and knees bent parallel to one another. During the backswing, the golfer's weight shifts from an equal balance to the back foot, while the stretched muscles and joints generate potential energy. Keeping the arms bent in the transition phase reduces the inertial forces of newton’s first law. The difference between the angle of their shoulders in relation to the hips, creates the ‘X-factor’ (Carroll, 2015). Studies have shown that a larger ‘X-factor’ results in greater power and subsequently distance of the ball. Due to the limitations of the study, only process measure was analysed, however comparison of the X-factor and biomechanics is a strong predictor of product outcomes. The downswing follows a circular-arc path to the point of ball contact, contracting muscles throughout the trunk region for the greatest transfer of potential to kinetic energy (Mcginnis & Nesbit, 2014). Energy is transferred to the ball via elastic collision forces, following newton's third law of motion (Cooper et al., 1974). Using eccentric muscle contraction, there is a deceleration of the body and club head during follow through completing the circular arc. Our videos show the paradox between universality and specificity, in that there is a general rate of improvement with age, however all tasks are unique to participant’s structural and functional characteristics.

[motordevelopment-blog1]

They say golf is like life, but don't believe them. Golf is more complicated than that

Gardner Dickinson

[motordevelopment-blog1]

Early Childhood: Saliah (age 6) 

The youngest participant was an active, and healthy 6-year-old girl named Saliah. During Saliah’s set-up phase, it is clear to see that she stands with a wider base of support than the rest of the participants in order to increase her stability. As a result of this increased stability, she loses her mobility, and the movement looks more stiff and rigid. This rigid form of movement prevents differential trunk rotation and is typical for someone of Saliah’s age and is seen across many other movement skills. This is referred to as the stability-mobility trade-off, and over time we see more of a balance of these two traits with experience and aging. Younger kids often rely more on visual information for balance and less on kinesthetic information, which is why during the backswing and follow-through, we see that Saliah is more off balanced, because she cannot fully determine where her body is in space to maintain her balance. Adult-like postural responses during a movement are not seen until about 7-10 years old, so her ability to maintain posture is still not developed (Haywood & Getchell, 2014, ch. 11). Directionality is the ability to understand the movement or location of an object in the environment, and this skill improves between the ages of 6 and 12 (Haywood & Getchell, 2014, ch. 101). Since Saliah falls on the lower end of this spectrum, she has not quite mastered her ability to detect objects around her, which is why we see a lack in her hand-eye coordination and miss-swing of the ball multiple times. A golf swing also requires laterality, since the club moves from one side of the body to the other. This skill does not often develop until 10 years old, so Saliah most likely has a more difficult time controlling her swing because she cannot properly conceptualize how the swing should be dealt with on both sides of the body, through backswing and follow through (Haywood & Getchell, 2014, ch. 102).

At 6-years-old, Saliah’s muscles are not fully developed and therefore it is much harder for her to generate a larger force to project the golf ball, and it is more difficult to coordinate her muscles into one fluid movement. Saliah has also never swung a golf club before, so because this task is so new to her and she has little experience, we see an individual constraint in function. Compared to the other participants, Saliah is performing outside and therefore she has to deal with other environmental factors of weather such as wind.

Saliah has a decreased range of motion (ROM) due to the stability-mobility trade-off. This rate limiter leads to less rotational velocity, which negatively affects the stretch of the muscles. The shorter radius in arms length and limited rotational velocity decrease her ability to create a large force and therefore will decrease the distance of the projectile (golf ball). Ultimately, the lack of muscle lengthening results in reduced potential and kinetic energy throughout her swing. In the end, Saliah demonstrates the typical task competencies and difficulties of an average 6-year-old.

[motordevelopment-blog1]

Forget your opponents; always play against par

Sam Snead

[motordevelopment-blog1]

Later Childhood: Jack (age 12)

The participant Jack is a 12-year-old boy who has been exposed to a variety of sports which have helped to speed up the development of his hand-eye coordination and body awareness (kinesthetics). Jack’s sense of balance allows him to address the ball with a more narrow stance than Saliah (6-years-old), to optimize his mobility over stability. Jack’s low muscle mass serves as an individual constraint and rate limiter preventing him from having a stronger back in the set-up phase and less power in his backswing and follow-through. When looking at a snapshot of his transition phase his shoulders are rotated back about 60° and his hips roughly 45°, although a proficient golfer would have a much larger difference between these two angles; Jack still has a larger X-factor than Luca (18-years-old). Although his shorter limb length and lower muscle mass would be expected to serve as a rate limiter for the distance of his shot,  Jack likely would have hit the ball further than Luca because of his larger X-factor and greater rotational velocity (Chu, Sell & Lephart, 2010). Jack exaggerates the medial rotation of his front knee instead of rotating from his hips on his backswing decreasing his stability and accuracy (Lynn & Noffal, 2010). Jack’s hand eye coordination allows him to confidently accelerate in his downswing, rotating sequentially from lower body to upper body through the ball, decelerating on the follow through and finishing with the club well behind his front shoulder. This full 360° rotation of the club head increases the rotational velocity and the radius of his limbs; two variables that predict the linear velocity of the projectile. Jack’s arms are straighter and he uses a larger range of motion in his swing than both Saliah and Luca suggesting that he would likely hit the ball harder than both of them.

There are many constraints individually, environmentally and specific to the task that limit Jack’s golf swing. The tiled floor, combined with Jack’s lack of footwear could have caused an increase in the internal rotation of his leading leg on the backswing due to decreased traction. This made it more difficult for him to delay the hip rotation on his backswing resulting in a decreased X-factor. Jack’s movement patterns are typical of someone his age, but his technique may be slightly better than average due to his golf experience.

[motordevelopment-blog1]

I know I am getting better at golf because I am hitting fewer spectators

Gerald Ford

[motordevelopment-blog1]

Adolescence: Luca (age 18)

The participant in the adolescence age group is an 18 year old boy named Luca who has never golfed before. Luca’s set up consists of a narrow stance while his posture is stooped forward, which compensates for his minimally flexed knees and hips. The lack of weight shifted from front-foot to rear-foot prevents the range of hip rotation as his backswing occurs. As the back swing takes place, Luca’s right arm flexes considerably, as his left arm remains quite flexed around a 140-degree angle. This arm placement is similar to Saliah’s form because both individuals are inexperienced golfers who flex their arms to reduce inertia. Luca’s back swing possesses minimal kinetic energy because of his minimal trunk differential rotation (Haywood & Getchell, 2014, ch. 3). This has lead Luca to have no gravitational potential energy at the top of his backswing due the lack of horizontal angling at the top.

Many constraints are evident within Luca’s biomechanical action. First off, Luca possesses structural constraints, such that his physical strength is under par. His lack of physical strength prevents maximal velocity and therefore acceleration of the swing, causing the ball to travel a short distance (Haywood & Getchell, 2014, ch. 11). An additional individual constraint may have been related to a behavioural function, such as a lack of attention or motivation (Haywood & Getchell, 2014, ch. 12). Another task constraint is Luca’s short club, as it causes him to hunch his back rather than flex his hips. Matching a golf club to the subject’s body composition is extremely important to afford Luca maximal velocity and accuracy. Therefore, the concept of body scaling Luca’s height and strength abilities to the size and fit of the club affords Luca a better swing outcome (Haywood & Getchell, 2014, ch. 2).

Due to Luca’s insufficient process measure, his product measure will be unsatisfactory. Starting with his set up, Luca should be properly aligned with the ball, as 50-60% of his weight should be on the back foot, ready to be transferred to the front foot (Maddalozzo, 1986). Luca can improve his posture by lengthening his shoulders, flattening his back, and keeping his hips at a 45-degree angle (Maddalozzo, 1986). If Luca increases the radius of the chain, and increases arm speed, the ball will generate more acceleration similar to Jack’s golf swing execution. To improve force, Luca should stretch and strengthen his internal and external obliques and abdomonis, as it will allow for greater differentiated trunk rotation. Luca’s follow through can improve if his head and wrists follow the plane of the swing path more accurately, similar to Ann’s follow through. Additionally, he can enhance his follow through by elongating the phase so that he finishes in a postural, balanced, and final position rather than bringing the club right back down to the ground. Lastly, Luca must work on his lateral weight transfer, as he remains flat-footed. This is noticeable because Luca does not slightly flex his right knee and does not lift his right heel off of the ground, such that Jack does considerably.

[motordevelopment-blog1]

Always make a total effort, even when the odds are against you

Arnold Palmer

[motordevelopment-blog1]

Older Adulthood: Ann (age 60)

Ann is an active 60 year old lady with a proficient golf swing. She sets up square to the ball, trunk flex less than the optimal 45-degree flexion, at around 40 degrees with an established static and dynamic stance. Upon set up she lines the golf club to close to the ground resulting in low-ball contact, undercutting the ball upward and reducing elastic collision forces in. As she winds up to hit the golf ball, her shoulders spiral back and away from the ball, creating a differential trunk rotation and generating potential energy. By bending her right arm, she is reducing the effect of inertia. Her downswing follows the appropriate circular-arc motion, accelerating at the point of contact. With age, there is a general decceleration upon contact for greater accuracy, however Ann does not follow this trend (Haywood & Getchell, 2014, ch. 9).  The rotation of her shoulders in relation to her hips throughout the swing does not quite follow the ideal ‘X factor’ formation that is required for optimal power, yet is greater than that of Saliah and Luca’s. During follow through, her body and club deceleration and her head and wrist continue to follow the plane of the swing path. Her end posture is rigid, possibly due to reduced flexibly of the muscle with age, subsequently decreasing her range of motion (Imagama et al., 2014). Postural stability is maintained throughout swing and finishes in a slightly unsteady position. Ann rebalances her weight with a step to the side in several attempts, expected of someone her age. Proprioceptive, vestibular input and vision required for postural stability and orientation, decline with aging (Kanekar & Aruin, 2014). Ann favored mobility to maintain stability during her follow through. Appropriately, her weight shifts from evenly distributed between her right and left foot to the back foot on the backswing and transfers to the front leg upon follow through.

For maximal power, contraction of the abdominal and back muscle need to be maintained to conserve kinetic energy throughout downswing and follow-through. Some energy appears to have been lost to non-contracted muscles in the trunk region, which may be attributed to degrading muscles with age. As an older adult, Ann has decreased muscle quality and increased weight relative to our younger participants resulting in specificity to her swing to overcome these differences. These structural constraints cause her to slow the speed of her swing, enabling her control and balance. Functionally, she remains determined and focused during her golf swings. Overall, Ann’s sequential movement (process measure) was that of an experienced golfer. A typically untrained older adult, may have significantly reduced kinesthetics, resulting in instability and inaccuracy. Ann’s golf experience and maintained physical activity level makes her more proficient and above average for her age.

[motordevelopment-blog1]

Mistakes are part of the game. It's how well you recover from them, that's the mark of a great player

Alice Cooper

[motordevelopment-blog1]

Conclusion

The proportional length and flexibility of the golf club is a constraint of the task for each participant. Proportional golf-club length for each participant is important for optimal set-up posture and consequently biomechanics of the swing. Flexibility of golf-club allows for lag time prior to ball contact, resulting in greater force upon contact (Fujikura, 2016). As none of our participants are expert golfers, flex is recommended for greater distance and velocity.

Furthermore, the absence of a golf hole prevents the swinger from having a point of reference for directionality and velocity, adding greater difficulty to the task. For Ann, Luca and Jack the environment is set indoors on tile with a wiffle ball which does not follow the usual setting for golf practice. The tiles do not provide the same level of traction in comparison to grass because the participants feet are not as secured on the tiles compared to grass. Therefore, the tiles and absence of cleats decreases traction, increasing the movement of their lower limbs and decreases their stability, thus preventing proper toe hold and execution of the swing. If product measures were required for analysis, the wiffle ball would be considered an additional task constraint for all participants. Based on Newton’s second law (F = ma), the wiffle ball would not travel as far as a golf ball due to its lighter mass. Additionally, the confinement of the walls around Jack, Anne and Luca could have provoked hesitation, in fear of the ball rebounding at them, altering the movement pattern of their swing, relative to swinging outdoors. In conclusion, motor development throughout the ages is reflective of the participants physiology and level of experience. Saliah (6) exhibits rigid stature with a wider base of support, similar to Ann (60). This is an example of older adults reverting back to fundamental movement patterns of developing children. Saliah’s lack of trunk rotation is comparable to Luca’s (18), as they both swing in the frontal plane with no weight transfer and little coordination. In contrast to Saliah and Luca, Jack and Ann have better weight transfer, increase in mobility and coordination. Although, Jack and Ann have better biomechanics overall, Jack’s exaggerated internal rotation of his left knee on his backswing reduces his X-factor compared to Ann. However, his increased range of motion in his follow through and balance affords him greater mobility and stability compared to the other participants. Our analysis of these four golfers follows a hyperbolic curve with the exception of Luca who falls outside of the normal developmental trend due to his limited athletic experience. Deliberate practice and experience are crucial for the proper development of a Tiger Woods quality swing…. or Dr. Liardi!

[motordevelopment-blog1]

Golf is deceptively simple and endlessly complicated

Arnold Palmer

[motordevelopment-blog1]

References

Lynn, S.K. & Guillermo, J.N. (2010). Frontal Plane Knee Moments in Golf: Effect of Target Side Foot Position at Address. Sports Science & Medicine, 9 (2), 275-281. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3761731/

Carroll, M. (n.d.). X-Factor Essentials: What it is and How to Train it. Retrieved March 26, 2017, from: http://www.mytpi.com/articles/fitness/x-factor_essentials_what_it_is_and_how_to_train_it

Chu, Y., Sell, T.C., & Lephart, S.M. (2010). The relationship between biomechanical variables and driving performance during the golf swing. Journal of Sports Sciences 28(11), 1251-1259.

Cooper, J.M., Bates, B.T., Bedi, J., & Scheuchenzuber, J. (1974). Kinematic and kinetic analysis of a golf swing. Biomechanics IV, 298-305. Doi: 10.1007/978-1-349-02612-8_44

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 1 [1]: Constraints, A Model for Studying Motor Devlopment).

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 1 [2]: Constraints, A Model for Studying Motor Devlopment).

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 2: Affordance and Body Scaling).  

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 3: Newton’s Laws of Motion).  

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 9: Manual Performance in Adulthood).  

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 10 [1]: Kinesthetic Development, Directionality).  

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 10 [2]: Kinesthetic Development, Laterality).

Haywood, K., & Getchell, N. (2014). Life span motor development. Champaign, IL: Human Kinetics (Chapter 11: Postural Control and Balance, Balance in Childhood).

How Much Flex should your gold shaft have? (n.d.). Retrieved March 26, 2017, from: http://www.fujikuragolf.com/knowledgebase/how-much-flex-should-your-golf-shaft-have/

Imagama, S., Hasegawa, Y., Wakao, N., Hirano, K., Muramoto, A., & Ishiguro, N. (2014). Impact of spinal alignment and back muscle strength on shoulder range of motion in middle-aged and elderly people in a prospective cohort study. European Spine Journal, 23(7), 1414-1419. doi:10.1007/s00586-014-3251-9

Kanekar, N., & Aruin, A. S. (2014). Aging and balance control in response to external perturbations: role of anticipatory and compensatory postural mechanisms. Age, 36(3). Doi: 10.1007/s11357-014-9621-8

Mcginnins, R.S., & Nesbit, S. (2014). Golf Club Deflection Characterisitics as a Function of the Swing Hub Path. The Open Sports Sciences Journal, 3(1), 155-164. Doi: 10.2174/1875399x01003010155

Maddalozzo, G. J. (1987). SPORTS PERFORMANCE SERIES: An anatomical and biomechanical analysis of the full golf swing. National Strength & Conditioning Association Journal, 9(4), 6. doi:10.1519/0744-0049(1984)009<0006:aaabao>2.3.co;2