July 2011

Original research: Skill level and balance in golf

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Previous research has identified superior balance in professional golfers compared with controls as well as associations between balance and skill level in amateur golfers. This study compared standing balance characteristics between profes­sion­al and highly skilled amateur golfers.

By Robert Donatelli, PT, PhD; Kenji Carp, PT, ATC, OCS; Guido Pagnacco, PhD; and John Adam, ATC       

With an estimated 55 million golfers worldwide, it’s fair to say golf is an extremely popular sport that influences the physical activity and lifestyle of many populations.1-4 Historically, golf was not considered a physically demanding sport, and perhaps this is why, until recently, golfers did not participate in the strength and conditioning programs common in other sports.1-3 Recent research, however, has validated the benefits of golf for cardiovascular and balance fitness.5,6 Likewise, recent studies have shown that exercise programs, including resistance training, core stability, and dynamic warm up, can improve strength, flexibility, and balance, as well as golf-specific performance markers.1-4

Relatively little research exists on the specific role balance plays in enhancing golf performance. Koslow et al examined patterns in center of gravity (COG) motion and shoulder and hip motion in highly skilled amateur golfers (defined as a sub-10 handicap), and found that club head speed correlated with the COG shifting exclusively in the intended direction of the flight of the ball during club impact.7 Likewise, they found that unskilled beginning amateur golfers exhibited variable COG shifting patterns outside of those commonly prescribed by golf teaching professionals. (Investigators defined the center of gravity as centered in the base of support from rear foot to front foot.)7

Figure 1: CAPS Professional System (Vestibular Technologies, Cheyenne, WY).

Jacobson et al8 studied 28 athletes who qualified for the National Collegiate Athletic Association (NCAA) National Tournament, correlating their skill level (as determined by season average round score) and movement in the center vertical force (or center of pressure [CoP]) from which the degree of weight shifting is derived. They found that higher skilled collegiate golfers demonstrated superior consistency of weight shifting and swing tempo.

Stemm et al9 examined standing limits of stability and postural sway in single leg stance among golfers at three skill levels and found no significant differences in balance measures between skill levels. Sell et al10 found golfers in the highest proficiency group (sub-0 handicap) had better balance than less skilled golfers (0-9 and 10-20 handicaps). In addition, golfers in the highest proficiency group had significantly greater hip strength, torso strength, shoulder strength, shoulder flexibility, hip flexibility, and torso flexibility than golfers in the lowest proficiency group (10-20 handicap) (p < 0.05).

Hosea et al found professional golfers were able to generate 34% more club head speed while using 50% less muscle activity than amateur golfers.11 This would suggest that one component of the professionals’ high degree of motor skill is efficient transfer of energy through the kinetic chain, which is partly accomplished through the shifting of body weight within the base of support or balance during swing.

Figure 2: Subject performing standing balance on CAPS Profes- sional System.

Lephart et al demonstrated that recreational golfers could enhance their golf performance using varied training modalities, including training for moderate resistance and flexibility and balance drills on compliant surfaces.1 However, their study design, which examined the effect of a multimodal exercise program, and its population, 15 trained male golfers (defined as golfers who play a round and practice at the driving range at least two to three times per week during the regular golf season), did not allow for analysis of the specific impact of balance training on golf performance. Thompson et al4 demonstrated that functional training and improving fitness in older golfers increased club head speed; this training also included balance exercises.

The current study

Whereas the studies described above were conducted on populations of varying skill levels, including some professional golfers, to date no comparative research has been conducted to assess balance characteristics in professional and amateur golfers. Likewise, some of the studies discussed above examined the impact of visual sensory feedback deprivation (i.e., eyes closed), which is typically thought to identify proprioception, i.e., joint position sense, or one aspect of somatosensory perception. However, none of the studies collected data using the Modified Clinical Test of Sensory Integration and Balance (mCTSIB),31,47 which allows for study of the impact of visual, somatosensory, and vestibular sensory integration on the golfer’s balance.

Thus, the primary objective of this study was to determine if differences in standing balance characteristics, including the impact of sensory integration, exist between professional and highly skilled amateur golfers (defined as a sub-10 handicap). A secondary objective was to examine correlations between the world ranking of professional players and any observed balance performance measures.

Methods

We used a cross-sectional study design to assess differences in standing balance between professional golfers and advanced amateur golfers. After obtaining permission from our institution’s Internal Review Board, we recruited and tested professional female golfers during an LPGA (Ladies Professional Golf Association) tournament. At the time of the study their age ranged from 20 to 47 years (mean age, 31.34; SD 7.3) while their world ranking ranged from second to 174th. All except one were right-handed.

Figure 3: mCTSIB—Normal stability, eyes open (NSEO). Figure 4: mCTSIB—Normal stability, eyes closed (NSEC). Figure 5: mCTSIB—Perturbed stability, eyes open (PSEO). Figure 6: mCTSIB—Perturbed stability, eyes closed (PSEC). Figure 7: Single leg stance golf swing take-away position. Figure 8: Single leg stance golf swing follow-through position.

We recruited the comparison group from a pool of advanced amateurs (sub-10 handicap), including 16 former professionals, who were clients of Physiotherapy Associates Strengthen Your Game Performance Testing Lab at Taylor Made/Addidas Golf’s “The Kingdom,” a golf teaching facility located in Carlsbad, CA. Inclusion criteria for the amateur control group were a golf handicap score >1 (as defined by Professional Golf Association [PGA] rules). It included 40 male and three female golfers who ranged in age from 15 to 67 years old (mean age, 38.81; SD 16.15). The golfers completed a data collection form in which they indicated their date of birth, height, weight, dominant side, and current LPGA world ranking (if any).

Golfers holding current PGA or LPGA tour cards were excluded from the amateur group. Further exclusion criteria for both groups were obvious conditions impacting balance or golf performance. The remaining potential participants underwent further screening with the Head Thrust Test, a sensitive and specific clinical test of peripheral vestibular hypofunction.12 These criteria, however, excluded no potential participants.

We collected experimental data with a portable computerized posturography system (Figures 1-2). The system consists of a three-component force platform with self-contained data acquisition electronics that is capable of simultaneously sampling all three forces needed to determine the CoP and vertical force with a very high resolution. It is powered and controlled using a laptop computer running the posturography system’s software and utilizes a foam cushion as a means to perturb participants’ balance. For all tests, posturographic force platform data were collected at 64 Hz.

Procedures

Each subject performed eight different balance tests, each lasting 20 seconds. Four of these tests were those that make up the mCTSIB. This commonly used series of tests assesses the influence of changing sensory inputs on balance by testing the golfer standing alternatively with eyes open and closed on stable and perturbing (e.g., foam cushion) surface conditions (Figures 3-6).

Four additional tests were performed in the initiating (take away) and ending (follow through) positions of the golf swing to assess the stability in those positions, which are the beginning and end of the phases of the golf swing (Figures 7-8). These four tests involved the subject standing in a single-limb stance on a stable surface (the platform) under eyes-open and eyes-closed conditions.

Each golfer also performed a limits of stability (LOS) test in which he or she was asked to lean at his or her own pace from the neutral double-limb stance position as far as possible in eight directions (forward, backward, rightward, leftward, forward-right, backward-right, backward-left, and forward-left) 45° apart without moving their feet.

Numerous studies across multiple populations that included golfers and other athletes have shown the mCTSIB and LOS computerized posturography protocols we used are valid clinical measures of balance with good test-retest reliability.5,7,8,9,13-24 Several studies have shown posturography measures of balance in single leg stance have fair to good test-retest reliability.25,26 Similarly, the posturography system used in this study has been shown to be a reliable measure of balance.27-31 Liston and  Brouwer,19 for example,  determined posturography is a reliable and valid measure of balance.

Statistical analysis

The stability score, used in several studies by other authors, was used as the primary equilibrium measure for the eight balance tests.27,32 It is defined as 1 minus the ratio between the measured sway during the test and the amount of sway a normal golfer of the same height as the test golfer should be able to tolerate before falling. (This is also known as the theoretical maximum sway, or the theoretical limit of stability, and is calculated using a regression formula based on the golfer’s height.)33

For convenience, the stability score is expressed as a percentage. Its definition makes it a convenient and easy-to-understand measure. In any test condition, a golfer able to stand perfectly still, i.e., with no measurable sway, will have a score of 100%, whereas one who sways as much as the theoretical limit of stability will have a score of 0%. Additionally, because of the way it is computed, the stability score has the advantage of being a type of measure normalized to the golfer’s height, simplifying its utility for comparing different subjects.

With regard to sensory integration, the Romberg Ratio48 was used to evaluate the effect of the suppression of visual inputs as well as that of the perturbing surface. The Romberg Ratio for visual dependence is the sum of the sway in the tests done with eyes closed divided by the sum of the sway of the tests done with eyes open. The ratio is typically >1, indicating that the sway increases with deprivation of visual input.

The effect of the perturbing foam cushion or deprivation of somatosensory input is computed as the sum of the sway of the tests on foam divided by the sum of the sway of the tests on the bare platform. Again, the ratio is typically >1, indicating that the sway increases when the subject is deprived of somatosensory input. Because the Romberg Ratio is an adimensional number, it can be used to compare participants without the need for normalization.

The LOS tests were analyzed considering the extreme sway reached in the eight positions, as computed by the posturography software. This was used to calculate the golfer’s LOS in the anterior-posterior and mediolateral directions. These were normalized to the golfer’s theoretical limit of stability obtained using a regression formula based on his or her height.34

This was used to calculate the golfer’s LOS in the anterior-posterior and mediolateral directions. These were normalized to the golfer’s theoretical limit of stability obtained using a regression formula based on his or her height.34

T-tests were used to determine the statistical significance of between-group differences for the eight static tests, the LOS test, and the Romberg Ratios. We also investigated the relationship between LPGA world ranking and measures of balance using linear, logarithmic, exponential, and power regression.

Results

The results for the mCTSIB testing demonstrated that, in general, the professional golfers had significantly better stability (i.e., less sway) than amateurs for all conditions except in the “normal surface, eyes closed” condition in which the differences were not statistically significant. The Romberg Ratios were >1 for both visual and somatosensory deprivation in both participant groups; however, no significant differences in Romberg Ratios were noted between groups.

For the single leg stance test, the minimum scores were often 0%, indicating that one or more golfers was not able to complete the test without losing control of his or her balance. Again, it appears that, on average, professionals had better stability than amateurs, although all golfers had very poor stability with eyes closed and differences between the two groups were statistically significant only for the eyes-open conditions. The much higher stability of professionals in the eyes-open conditions and especially in the follow through stance might also be related to their better golf performance.

The results for the LOS testing demonstrated no significant differences between the two groups. Both groups seem to have better mediolateral than anterior-posterior control of postural sway, and most subjects appeared to stand relatively posterior compared to the center of their limits of stability (actual base of support), indicating that the CoP during quiet stance was posterior relative to center of their base of support.

The regression analysis did not show a strong correlation between world ranking and any of the considered measures, with R2 values <0.02.

Discussion

Previous research has identified superior balance in professional athletes compared with controls as well as associations between balance and skill level in amateur golfers.7-9,35,36 Thus, it is not surprising that other authors have demonstrated that training programs including strength, power, flexibility, and balance components can enhance golf-specific sports performance.1-4 Studies have also shown that regular participation in golf comes with several health benefits, including enhanced balance.5,6 However, no previous studies have examined differences in postural control between groups of skilled amateur and professional golfers. The current study demonstrates that aspects of standing balance performance are superior in professional golfers.

Sensory integration and balance

The significant differences in normal stability, eyes open (NSEO); perturbed stability, eyes open (PSEO); and perturbed stability, eyes closed (PSEC) conditions of the mCTSIB suggest that professional golfers process visual and vestibular sensory cues more efficiently than their amateur counterparts. In this aspect, our findings are consistent with previous findings.13-20

Conversely, we found no significant differences between groups with the normal surface, eyes open (NSEC) condition of the mCTSIB. This suggests that professional and amateur golfers process somatosensory input similarly, which is somewhat surprising given the heightened somatosensory perception demonstrated by elderly golfers and athletes in other sports compared with controls.5,35,36

Romberg Ratios >1 for both the visual and somatosensory biased analysis within each group indicate balance in both professionals and amateurs was impacted by deprivation of visual and somatosensory input, respectively. This is consistent with numerous findings of other investigators who used the mCTSIB or other computerized posturography protocols that manipulate sensory biasing.13-24 However, no significant differences in Romberg Ratios were noted between professional and amateur golfers. So although both professionals and amateurs prefer to use visual and somatosensory information if available, a strong visual or somatosensory preference or dependence on these senses does not explain the heightened balance performance observed in professionals.

The authors also hope the findings highlight the error inherent in the common practice of referring to any balance deficits in athletic populations as synonymous with impaired proprioception. As with most areas of rehabili­tation or performance enhancement, identifica­tion of specific impair­ments should shape our interventions. Thus, sports medicine professionals should utilize sensory-specific balance tests such as the mCTSIB and possibly the Balance Error Scoring System49 to evalu­ate balance in amateur and professional athletes parti­ci­pat­ing in all sports. In turn, golf-specific rehabili­tation and enhancement training programs should include sensory-specific neuromuscular training to improve sensitization of the nervous system in re­sponse to sensory specific inputs.

Previous outcomes research has demonstrated the benefits of balance training programs in numerous populations, including people with vestibular pathologies, stroke, Parkinson disease, and multiple sclerosis, as well as in elderly and athletic populations.13,16,17,19,20,22,30,39-41,45 The findings of this study suggest many golf athletes, even those without a concomitant injury that would effect somatosensation or proprioception, should perform visual and vestibular sensory specific neuromuscular training.

Single leg stance balance tests

Professional golfers demonstrated significantly better postural stability in single leg stance under the “eyes open, take away” condition than their highly skilled amateur counterparts. Previous studies have found that single leg stance balance in dancers differs significantly from non-dancers and from athletes in other sports.35,36 Professional golfers appear to be most stable in single leg stance with eyes open and in the follow-through position. This is consistent with previous findings that follow-through side hip strength correlates with skill in golf and with numerous studies showing that gluteus muscle group strength impacts standing balance in golfers.37 Our findings suggest that ability to control posture at the extreme start and end of the golf swing (take away and follow through, respectively) may also be indirect measures of dynamic postural control during the golf swing. This may prove to be of great clinical utility, as the ability to reliably study the extremely fast movement of swinging a golf club has proved difficult in even highly sensitive, technologically advanced, and expensive biomechanical laboratories.

Interestingly there was not a statistically significant difference in stabilometry (static posturography) between groups in single leg stance with eyes closed. In fact, both groups had very poor stability in single leg stance with eyes closed. Many subjects were not able to complete the test, resorting to touching the contralateral limb to the ground prior to the end of the trial. It appears the current somatosensory biased balance tests in double or single leg stances were not par­ticularly sensitive for ability in golf. This contrasts with previous studies of single leg stance with and without visual fixation that showed somatosensory biasing improved the sensitivity of testing.25,26,30 Similarly, a study of the mCTSIB suggested that the addition of alternate head positions may improve test sensi­tivity.38 However, these studies did not add sport-specific alterations of hip and trunk position.

It is quite possible that the addition of take-away or follow-through golf-specific stances, when combined with visual sensory deprivation, was simply too difficult for either participant group. Further study of balance testing, employing dual variables of sensory inte­gration and golf-specific stances, could further delineate the sensitivity of these posi­tions. Since golf-specific single leg stance with the eyes closed obviously provides an ample error signal to the nervous system, it also would appear to be a fertile area for golf-specific balance training.

Limits of stability

Our study found no significant differences in LOS between the two groups. This was in agreement with previous study of LOS in amateur golfers of varying skill levels as defined by their golf handicap.9 Both groups appeared to have better ability to sway (shift weight) in mediolateral than in anterior-posterior planes. In our study most golfers appeared to stand relatively posterior to the center of their LOS. This could represent a learned postural change that allows for greater rotation of the lower extremities during golf swing, but obviously further research is required to examine these proposed links.

Limitations

It is important to ack­nowledge that our professional group con­sisted of 23 female athletes, all from the ranks of the LPGA, while our comparison group contained 40 male and three female golfers. Despite the recent increase the LPGA’s public popularity, it proved difficult to obtain sufficient gender-matched participants who were also highly skilled amateur golfers. However, for several reasons, the authors feel this does not significantly limit the findings of our current comparative study.

First, numerous previous studies using computerized posturography have demonstrated differences in postural stability with age-related changes, skill in sport, physical activity, balance training programs, cognitive function, numerous pathologies, and height, but without significant gender interaction.5,7,9,13,14,17,21-27,29,30,35-46 For example, Steffen and Mollinger recently examined the effect of age, gender, and height across multiple noncomputerized clinical balance tests and found gender was not a con­sistently significant predic­tor of balance testing.46

Given that our study did account for age and height through the use of the stability score mea­sure of posturography, and because it appears that gender is not an issue in balance at any skill level, we feel it is rea­sonable to project our findings to all professional and highly skilled amateurs.33,34

Conclusion

The findings of this study demonstrate that pro­fes­sional golfers possess superior balance when compared with ama­­­teurs, even highly skilled amateurs. The apparent mechanism for this dif­ference appears to be greater efficiency in pro­cessing visual and vestibular, rather than somatosensory, or proprioceptive, sensory input. In addition, this study shows the clinical utility of competent assessment of the impact of sensory integration on neuromuscular control of balance in the assessment and treatment of golfers.

Tests traditionally used following mild traumatic brain injury or in neurological rehabilitation settings can and should be used with golfers and other athletic populations. The golf stance and sensory specific balance testing protocols utilized in this study may have greater sensitivity than conventional methods when studying athletes, and may provide a means of enhancing performance for all golfers. Further research into the impact of visual and vestibular sensory processing and visual/vestibular interactions with sport-specific stances is warranted. It also appears that professional golf ranking does not correlate with specific clinical balance measures.

Robert Donatelli, PhD, PT, is director of Sports Outreach Programs at Physiotherapy Associates in Las Vegas, NV. Kenji Carp PT MPT, OCS, ATC, is a certified vestibular therapist and director and owner of Cooperative Performance and Rehabilitation in Eugene, OR. Guido Pagnacco, PhD, is vice president of Vestibular Technologies in Cheyenne WY, and adjunct professor of electrical and computer engineering at the University of Wyoming in Laramie. John Adam, ATC, has been head athletic trainer for a number of professional sports teams and is currently a PGA Tour trainer.

REFERENCES

1. Lephart SM, Smoliga JM, Myers JB, et al. An eight-week golf-specific exercise program improves physical characteristics, swing mechanics, and golf performance in recreational golfers. J Strength Cond Res 2007;21(3):860-870.

2. Fradkin AJ, Sherman CA, Finch CF. Improving golf performance with a warm up conditioning programme. B J Sports Med 2004;38(6):762-765.

3. Doan BK, Newton RU, Kwon Y, Kraemer WJ. Effects of physical conditioning on intercollegiate golfer performance. J Strength Cond Res 2006;20(1):62-72.

4. Thompson CJ, Cobb KM, Blackwell J. Functional training improves club head speed and functional fitness in older golfers. J Strength Cond Res 2007;21(1):131-138

5. Tsang WW, Hui-Chan CW. Effects of exercise on joint sense and balance in elderly men: Tai Chi versus Golf. Med Sci Sports Exerc 2004;36(4):658-667.

6. Parkkari DH, Natri A, Kannus P, et al. A controlled trial of the health benefits of regular walking on a golf course. Am J Med 2000;109(2):102-108.

7. Koslow R. Patterns of weight shift in the swings of beginning golfers. Percept Mot Skills 1994;79(3 pt 1): 1296-1298.

8. Jacobson BH, Stemm JD, Redus BS, et al. Center of vertical force and swing tempo in selected groups of elite collegiate golfers. Sport Coaching Journal 2005;1(2);1-6.

9. Stemm JD, Jacobson BH, Royer TD. Comparison of stability and weight shift among golfers grouped by skill level. Percept Motor Skills 2006;103(3):685-694.

10. Sell TC, Tsai YS, Smoliga JM, et al. Strength, flexibility, and balance characteristics of highly proficient golfers. J Strength Cond Res 2007;21(4):1166-1171.

11. Hosea TM, Gatt CG, Galli KM, et al. Biomechanical analysis of the golfer’s back. In: Cochran AJ, ed. Science and Golf: Proceedings of the World Scientific Congress of Golf Science and Golf I, July 1990; St. Andrews. London: E & FN Spon;1990:43-48.

12. Schubert MC, Tusa RJ, Grine LE, Herdman SJ. Optimizing the sensitivity of head thrust test for identifying vestibular hypofunction. Phys Ther 2004;84(2):151-158.

13. Mirka A, Black FO. Clinical application of dynamic posturography for evaluating sensory integration and vestibular dysfunction. Neurol Clin 1990;8(2):351-359.

14. Furman JM. Posturography: uses and limitations. Baillieres Clin Neurol 1994;3(3):501-513.

15. Lipp M, Longridge NS. Computerised dynamic posturography: its place in the evaluation of patients with dizziness and imbalance. J Otolaryngol 1994;23(3):177-183.

16. Furman JM. Role of posturography in the management of vestibular patients. Otolaryngol Head Neck Surg 1995;112(1):8-15.

17. Di Fabio RP. Sensitivity and specificity of platform posturography for identifying patients with vestibular dysfunction. Phys Ther 1995;75(4):290-305.

18. Ford-Smith CD, Wyman JF, Elswick RK, et al. Test-rest reliability of the sensory organization test in noninstitutionalized older adults. Arch Phys Med Rehabil 1995;76(1):77-81.

19. Liston RA, Brouwer BJ. Reliability and validity of measures obtained from stroke patients using the Balance Master. Arch Phys Med Rehabil 1996;77(5):425-430.

20. El-Kashlan HK, Shepard NT, Asher AM, Smith-Wheelock M, Telian SA. Evaluation of clinical measures of equilibrium. Laryngoscope 1998;108(3):311-319.

21. Riemann BL, Guskiewicz KM. Effects of mild head injury on postural stability as measured through clinical balance testing. J Athl Train 2000;35(1):19-25.

22. Black FO. Clinical status of computerized dynamic posturography in neurology. Curr Opin Otolaryngol Head Neck Surg 2001;9(5):314-318.

23. Boulgarides LK, McGinty SM, Willett JA, Barnes CW. Use of clinical and impairment-based tests to predict falls by community-dwelling older adults. Phys Ther 2003;83(4):328- 339.

24. Newstead AH, Hinman MR, Tomberlin JA. Reliability of the Berg Balance Scale and balance master limits of stability test for individuals with brain injury. J Neurol Phys Ther 2005;29(1):18-23.

25. Forkin DM, Koczur C, Battle R, Newton RA. Evaluation of kinesthetic deficits indicative of balance control in gymnasts with unilateral chronic ankle sprains. J Orthop Sports Phys Ther 1996;23(4):245-250.

26. Hertel J, Gay MR, Denegar CR. Differences in postural control during single-leg stance among healthy individuals with different foot types. J Athl Train 2002;37(2):129-132.

27. Girardi M, Konrad HR, Amin M, Hughes LF. Predicting fall risks in an elderly population: computer dynamic posturography versus electronystagmography test results. Laryngoscope 2001;111(9):1528-1532.

28. Amin M, Girardi M, Konrad HR, Hughes L. A comparison of electronystagmography results with posturography findings from the BalanceTrak 500. Otol Neurotol 2002;23(4):488-493.

29. Carrick FR, Oggero E, Pagnacco G. Posturographic changes associated with music listening. J  Altern Complement Med 2007;(5):519-526.

30. Carrick FR, Oggero E, Pagnacco G, et al. Posturographic testing and motor learning predictability in gymnasts. Disabil Rehabil 2007;29(24):1881-1889.

31. Pagnacco G, Oggero E, Carrick FR. Repeatability of posturographic measures of the mCTSIB static balance tests-a preliminary investigation. Biomed Sci Instrum 2008;44:41-46.

32. Topper AK, Maki BE, Holliday PJ. Are activity-based assessments of balance and gait in  the elderly predictive of risk of falling and/or type of fall? J Am Geriatr Soc 1993;41(5):479-87.

33. Webb P, ed. Bioastronautics Data Book, NASA SP-3006. Washington, DC, National Aeronautics and Space Administration;1964.

34. Ogden T, Fryar CD, Carroll MD, Flegal KM. Mean bodyweight, height, and bodymass index. United States, 1960–2002. Advance data from vital and health statistics;347. Hyattsville, Maryland: National Center for Health Statistics;2004.

35. Crotts D, Thompson B, Nahom M, et al. Balance abilities of professional dancers on select balance tests. J Orthop Sports Phys Ther 1996;23(1):12-17.

36. Schmit JM, Regis DI, Riley MA. Dynamic patterns of postural sway in ballet dancers and track athletes. Exp Brain Res 2005;163(3):370-378.

37. Tasi YS, Sell TC, Myers JB, et al. The relationship between hip muscle strength and golf performance. Med Sci Sports Ex 2004;36(5):2-9.

38. Chandra NS, Shepard NT. Clinical utility of lateral head tilt posturography. Am J Otol 1996;17(2):271-277.

39. Westlake KP, Culham EG. Sensory-specific balance training in older adults: effects on proprioceptive reintegration and cognitive demands. Phys Ther 2007;87(10):1274-1283.

40. Woollacott MH, Shumway-Cook A. Changes in posture control across the life span – a systems approach. Phys Ther 1990;70(12):799-807.

41. Berger L, Chuzel M, Buisson G, Rougier P. Undisturbed upright stance in control in the elderly: Part 1. Age-related changes. J Mot Behav 2005;37(5):348-358.

42. Berger L, Chuzel M, Buisson G, Rougier P. Undisturbed upright stance control in the elderly: Part 2: Postural-control impairment of elderly fallers. J Mot Behav 2005;37(5):359-366.

43. Shaffer SW, Harrison AL. Aging of the somatosensory system: a translational perspective. Phys Ther 2007;87(2):193-207.

44. Teasdale N, Stelmach GE, Breunig A. Postural sway characteristics of the elderly under normal and altered visual and support surface conditions. J Gerontol 1991;46(6):B238-244.

45. Dibble LE, Addison O, Papa E. The effects of exercise on balance in persons with Parkinson’s Disease: A systematic review across the disability spectrum. J Neurol Phys Ther 2009;33(1):14-26.

46. Steffen TM, Mollinger LA. Age- and Gender-related test performance in community dwelling adults. J Neurol Phys Ther 2005;29(4):181-189.

47. Loughran S, Tennant N, Kishore A, Swan IR. Interobserver reliability in evaluating postural stability between clinicians and posturography. Clin Otolaryngol 2005;30(3):255-257.

48. Cornilleau-Pérès V, Shabana N, Droulez J, et al. Measurement of the visual contribution to postural steadiness from the COP movement: methodology and reliability. Gait Posture 2005;22(2):96-106.

49. Finnoff JT, Peterson VJ, Hollman JH, Smith J. Intrarater and interrater reliability of the Balance Error Scoring System (BESS). PM R 2009;1(1):50-54.

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