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Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion
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Journal of Science and Medicine in Sport 13 (2010) 196–201
Original paper
Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion Anthony G. Schneiders a,∗ , S. John Sullivan a , Andrew R. Gray b , Graeme D. Hammond-Tooke c , Paul R. McCrory d a Centre for Physiotherapy Research, University of Otago, New Zealand Department of Preventive & Social Medicine, University of Otago, New Zealand c Department of Medical & Surgical Sciences, University of Otago, New Zealand Centre for Health, Exercise & Sports Medicine, University of Melbourne, Australia
b d
Received 21 September 2008; received in revised form 6 April 2009; accepted 8 May 2009
Abstract Postural control and motor coordination are essential components of normal athletic activity. Tasks involving balance and coordination are used to determine neurological function in sports-related concussion. Determining normative values for these tasks is therefore essential to provide sports medicine professionals with a frame of reference with which to interpret clinical measures obtained from players suspected of sustaining a concussion. One hundred and seventytwo healthy subjects (16–37 yrs) performed three timed tests: Tandem Gait (TG); Fingerto-Nose (FTN); Single-Leg-Stance (SLS) on firm and foam surfaces. Unadjusted geometric means (±SD) for each measure were averaged across three trials. Time to complete TG was 11.2 ± 1.2 s. FTN for the dominant and non-dominant arm were 2.9 ± 1.1 s and 3.0 ± 1.2 s, respectively. SLS values for dominant and non-dominant leg were 20.4 ± 3.0 s (firm), 3.4 ± 1.6 s (foam), and 21.0 ± 2.9 s (firm), 3.3 ± 1.6 s (foam), respectively. For TG, there was an order effect (P < .001) but no age, sex or BMI effects. FTN demonstrated a dominant arm preference (P < .001), sex (P = .006), BMI (P = .043) and order effects (P < .001). SLS demonstrated an order effect on the firm surface (P = .009) and an order (P < .001) and BMI (P = .001) effect on foam. Intra-rater reliability, as measured by ICC (3,3), demonstrated that TG and FTN had excellent reliability compared to SLS. FTN and TG should continue to be used in test batteries to determine neurological function in sports-related concussion. © 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Keywords: Normal values; Postural balance; Coordination impairment; Reliability; Time
Postural control and motor coordination are essential for normal daily activities1,2 and a crucial requirement for athletic events and activities.3 Maintaining postural equilibrium requires the central nervous system to process and integrate afferent information from the somatosensory, visual, and vestibular systems and execute appropriate and coordinated musculoskeletal responses.4 Impairments in postural control mechanisms, due to disease or injury, are termed postural instabilities and result in motor performance deficits including increased postural sway and poor coordination.3,5 Motor performance tasks involving balance and coordination are used to determine neurological function.6 Static ∗
Corresponding author. E-mail address: [email protected] (A.G. Schneiders).
balance control, dynamic gait execution and upper limb coordination are assessed in individuals presenting with neurological dysfunction due to sports-related traumatic head injury,7–9 where they are often included as standardised components of the screening process. Coordination is usually evaluated by observing the quality and speed of alternating repeated movements1 and the Finger-to-Nose test (FTN) is one of the key components of the neurological examination used to assess this domain.10 Balance tasks are also used as surrogate measures of motor performance. The most common clinical uni-pedal balance task is the Single Leg Stance (SLS), which is often performed under varying conditions (e.g. firm/compliant surface, eyes open/closed) in order to challenge components of the sensory-feedback system.11,12 Gait parameters are also used to determine neurological
1440-2440/$ – see front matter © 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jsams.2009.05.004
A.G. Schneiders et al. / Journal of Science and Medicine in Sport 13 (2010) 196–201
function,8 and Tandem Gait (TG) can be used as a clinical test to assess dynamic balance during locomotion.13,14 While SLS has previously been used to screen for sports-related concussion (SRC),7 the use of FTN in this context has been limited,15 and TG has not been previously used. However, as these tests are commonly used as evaluations of neuromotor function, they have the potential to act as valuable screening items in the assessment of sports-related concussion. It is therefore important that sports medicine clinicians have the ability to quantify motor performance tasks in order to determine function in patients presenting with neurological disorders and the constant ‘time’ can be readily utilised to facilitate this. There is limited normative data available on motor performance tasks despite their widespread use as neurological test instruments.16 The development of norms is important because motor performance can be affected by age and other intrinsic factors.17–20 The establishment of norms could therefore help clinicians distinguish between performances attributable to pathology and those attributable to the normal process of aging or other factors.21 Development of normative data can also improve the objectivity associated with common motor control measurements that assess coordination and balance. This is vital so that sports medicine professionals are able to reliably assess clinical motor performance in order to determine levels of impairment and to plan and evaluate appropriate interventions and rehabilitation. While previous studies have commonly measured clinical balance and coordination in older people,1,13,22,23 limited data are available in younger populations.2 This is particularly important because conditions such as sports-related mild traumatic brain injury (MTBI) often occur in younger populations.24 The Sport Concussion Assessment Tool (SCAT) was developed by McCrory et al.25 following the 2nd International Conference on Concussion in Sport, held in Prague in 2004. The intent was to develop a standardised assessment tool via international expert consensus that could be used globally for sideline assessment of sports concussion as well as for patient education. While many items of the SCAT have been developed and validated for inclusion, the Neurological Screening component of the assessment remains qualitative and limited in its utility. The development of quantitative tools that screen for neurological dysfunction attributable to SRC is an important component of the development of the SCAT which is considered “a work in progress”.25 Tests of motor performance that have been suggested to screen for the neurological component of sports-related concussion include FTN,15 SLS26 and qualitative measures of gait assessment.25 The establishment of norms for these tests will provide sports medicine professionals with a frame of reference to interpret clinical measures obtained from players suspected of a concussion. This could be pivotal in making the correct decision regarding withdrawal of a player from sport and their subsequent triage. It will also provide objec-
197
tive data to assist in assessing and monitoring rehabilitation progress and return to play/sport protocols. The aim of this study was to determine normal values for three timed tests of motor performance for use in the assessment of neurological function in players suspected of sustaining a sports concussion. A secondary aim was to establish the intra-rater reliability of these measures.
1. Methods A prospective cross-sectional design with repeated measures was used for the development of normative values and to determine intra-rater reliability of the selected measures. A sample size of 120 was the absolute minimum required for the calculation of 90% confidence intervals for 5% and 95% non-parametric reference interval limits.27 A convenience sample of healthy male and female subjects aged between 15 and 40 yrs were recruited from high schools, tertiary institutions, and sports clubs in a metropolitan area through advertisements and public notices. Subjects were screened for the following exclusion criteria: recent (<3 mths) musculoskeletal or neurological injuries which could interfere with performance; known neurological, psychiatric, or psychological disease; use of drugs or alcohol that might affect motor tasks; and inability to give informed consent. All subjects gave written informed consent to be involved in the study and ethics approval was obtained from the University of Otago Human Ethics Committee. Data collection took place in a quiet laboratory at a University Research Centre and was conducted by physical therapists instructed in the administration and scoring procedures of the test battery. The sequence of administration of the three tests and their components was balanced by a block randomisation process across subjects to control for potential order effects. Short rest intervals were provided between trials and tasks in order to reduce fatigue and to optimise performance. All trials were completed without footwear. Upper and lower limb dominance was determined by a dichotomous self-report preference survey. Intra-rater reliability of the motor performance measures was assessed by repeating the test using the same examiner 1 week after the initial test. The repeat testing was performed at the same time of day to counter potential diurnal variation. The repeat test order was block randomised to minimise order bias. Each test was demonstrated once by the examiner and participants were then allowed one practise trial to ensure that they could perform the task required. Three trials of each condition were timed with a calibrated stopwatch accurate to 0.01 s (Oregon Scientific, Portland, OR). Subjects who failed a trial (incorrect performance) were required to repeat it. FTN assessed upper limb coordination and speed. The starting position was seated in a chair with a back rest with the test arm outstretched, shoulder flexed to 90◦ , and elbow and index finger extended. The head remained stationary and
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eyes were open. When an audible start signal was given, the subjects performed five successive Finger-to-Nose repetitions using their index finger to touch the tip of the nose as quickly and as accurately as possible. The arm returned to the starting position for completion of the test.28 Subjects failed the test if they did not touch their nose, fully extend their elbow or did not perform five repetitions. Three trials were recorded for each limb. SLS on Floor and Foam was used to measure static balance.29 Subjects were instructed to keep their hands on their hips and their eyes closed. Subjects maintained their balance for as long as possible while standing on their test leg with their eyes closed, on a firm surface and on a foam balance pad (Airex Balance pad, 50-kg/m3 , Alusuisse, CH). A 10 s rest was given between each trial. The test was terminated when the subjects: opened their eyes; touched the floor with their non-test leg; broke contact with the support surface with their standing foot; removed their hands from their hips. Three trials were recorded for each leg and each surface condition. TG was used to measure dynamic balance, speed and coordination.13,14 The subjects began the task standing with their feet together behind a starting line. Subjects walked along a 38 mm wide, 3 m line with an alternate foot heel-totoe gait. Once they reached the end of the 3 m track, they turned 180◦ and returned along the track to the start point.28 Subjects failed the test if they did not maintain approximation between their heel and toe, deviated from the track, or did not turn behind the end of the line. Three trials were recorded. Data analysis was performed using SAS (SAS 9.1.2). Data for all statistical models were log-transformed if marginal and conditional residuals were skewed and geometric means and standard deviations were calculated for each test condition; both for individual trials and for arithmetic mean
performance over all trials. Statistical analyses were based on linear mixed models controlling for age, sex, age-bysex, BMI, and sequence (trials 1–6 for FTN and TG and 1–12 for SLS), with a random subject effect to account for the repeated measures. For TG, foot length and foot width were included, and for FTN, a dominant arm indicator and arm length. A dominant leg indicator, foot length and foot width were included for SLS. Denominator degrees of freedom were determined using Satterthwaite’s approximation. A statistical significance level of P < 0.05 was used for all data. Intra-rater reliability for each measure were computed using the Intra-Class Correlation (3,1) (3,3) (ICC) statistics with the assumption of a random effect for subjects.
2. Results One hundred and seventy-two subjects (F = 110, M = 62) aged 16–37 (mean ± SD, 22.18 ± 3.84) were recruited into the study. Demographic details are presented in Table 1. The mean of each individual trial and the mean of three trials for each motor performance task are shown in Table 2. For FTN, the subject’s first trial was slower than subsequent trials (P < 0.001) however the differences were small and not considered clinically important (<0.09 s), falling within the estimated margin of error when using a hand-held stopwatch. FTN was significantly faster in the dominant/preferred limb (P < 0.001) which equated to a 4% increase in speed. There was evidence that males were 7% faster than females (P = 0.006) and a higher BMI was associated with slower performance times (P = 0.043). For TG there was a significant order effect noted (P < 0.001) which was due to a quicker third trial. Age, sex and BMI were not associated with the time to perform TG.
Table 1 Subject characteristics. Variable
Mean ± SD Females (n = 110)
Range
Mean ± SD Males (n = 62)
Range
Mean ± SD Combined (n = 172)
Range
Age (yr) Mass (kg) Height (cm) BMI Leg dominance Arm dominance
21.6 ± 3.3 62.8 ± 8.5 164.7 ± 6.5 23.1 ± 2.8 14 left 10 left
17–34 42–98 136–180 17–36 96 right 100 right
23.1 ± 4.5 77.1 ± 14.7 178.3 ± 7.8 24.2 ± 3.7 11 left 2 left
16–37 48–130 157–194 19–38 51 right 60 right
22.2 ± 3.8 67.9 ± 13.1 169.6 ± 9.5 23.5 ± 3.2 25 left 12 left
16–37 42–130 136–194 17–38 147 right 160 right
Table 2 Individual trial mean ± SD (geometric) and mean ± SD (arithmetic) of trials 1–3. Time in seconds (n = 172). Measure
Trial 1
Finger-to-Nose (D) Finger-to-Nose (ND) Single Leg Stance Firm (D) Single Leg Stance Firm (ND) Single Leg Stance Foam (D) Single Leg Stance Foam (ND) Tandem Gait
3.0 3.1 13.5 14.5 2.9 2.7 11.3
D = dominant; ND = non-dominant. a Arithmetic mean.
± ± ± ± ± ± ±
Trial 2 1.1 1.2 4.1 3.6 1.8 1.6 1.2
2.9 3.0 16.0 17.6 3.1 3.2 11.2
± ± ± ± ± ± ±
Meana of 3 trials
Trial 3 1.2 1.2 3.5 3.6 1.8 1.8 1.2
2.9 3.0 19.5 17.2 3.4 3.3 11.0
± ± ± ± ± ± ±
1.2 1.2 3.6 3.4 1.80 1.9 1.2
2.9 3.0 20.4 21.0 3.4 3.3 11.2
± ± ± ± ± ± ±
1.1 1.2 3.0 2.9 1.6 1.6 1.2
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Table 3 Intra-class coefficients. Measure
Finger-to-Nose (D) Finger-to-Nose (ND) Single Leg Stance Firm (D) Single Leg Stance Firm (ND) Single Leg Stance Foam (D) Single Leg Stance Foam (ND) Tandem Gait
Intra-rater-same session (N = 172)
Intra-rater–between sessionsa (N = 40)
ICC (single)
ICC (average)
ICC (single)
ICC (average)
0.864 0.863 0.420 0.394 0.195 0.260 0.919
0.950 0.950 0.685 0.661 0.420 0.514 0.971
0.696 0.689 0.142 0.406 0.012 0.000 0.544
0.821 0.816 0.249 0.578 0.024 0.000 0.705
D = dominant; ND = non-dominant. a First trial in each session.
SLS on a firm surface demonstrated an order effect with a first trial that was of shorter duration compared to trials 2 and 3 (P = 0.009) but no significant improvement occurred in SLS time after the second trial. For the foam surface the most significant order effect (P < 0.001) occurred when the firm condition preceded the foam testing. There was no order effect when foam was performed first. Intra-rater reliability of the motor performance measures was assessed by the same examiner both during the same test session and then 1 week following the initial testing. A total of 172 subjects performed multiple trials on the same day and a convenience sample of 40, with comparable demographics (25 F:15 M; age 21.7 ± 2.9; weight 65.7 ± 8.1; height 170.0 ± 7.8; BMI 24.0 ± 8.8), agreed to return and were retested 1 week later. Intra-Class Correlation (ICC) coefficients were calculated for a single point estimate (first trial), and also calculated as a mean of the three trials. The data presented in Table 3 shows that FTN and TG were the most robust measures on repeated testing.
3. Discussion This study is the first to report normative values for timed versions of TG and SLS. FTN data has been reported previously, although in different populations.21 Using similar methodology; Swaine et al.21 reported a mean value of 3.44 s for the right arm and 3.56 s with the left arm for FTN. This study reports values approximately 20% quicker for FTN in a similar age cohort and it is unclear why these values differ given the standardisation of the test and the reliability of the data. One explanation could be that the participants of the two studies were different in terms of physical characteristics including height and mass. In this current study, BMI was shown to be associated with performance as a function of time during the FTN test. However this comparison can not be verified as subject characteristics were not reported by Swaine et al.21 This study demonstrated a gender effect for FTN with males significantly faster than females which does not concur with previous research,1,21,30 however this difference was small (0.12 s) and unlikely to be clinically important in a screening examination. No gender effect was noted for the
postural measures (SLS/TG) in this study, a finding noted in previous studies.19 No age effect was noted for any motor performance measure in this study which was most likely due to the limited age range of the cohort, where over 80% of participants were aged 18–24 yrs. Although motor abilities, including strength, flexibility and coordination, have been shown to decline with age,31 other studies have only demonstrated significant deterioration in balance from the 4th decade.2,31 In this study, a higher BMI resulted in significantly slower performance times on FTN scores and less ability to maintain static balance on an unstable surface. This finding was independent of arm dominance and gender for FTN and has not been previously reported. No clear explanation exists for this finding, but mass dependent inertia of the upper limb may be a factor. The FTN and TG proved to be precise and reliable tests when administered by the same evaluator. These tests can therefore provide a dependable measure of upper limb coordination and lower limb dynamic balance in healthy individuals. There is therefore potential for these tests to be used to neurologically screen for sports-related concussion once they are sufficiently examined for specificity and sensitivity to this condition. The low reliability of the SLS measures may be due to the wide performance variability. Jonsson et al.22 determined that the ability to maintain a static posture during SLS was dependent on a reduced initial decrease in force variability which occurs within the first 5 s of the task, presumably as part of a central balance control strategy. The within and between subject variability in static clinical balance tests is suggested as a hallmark of normal balance performance.32 Another characteristic of motor performance tests is the learning effect that occurs with these tasks.28,29 This study demonstrated that the first trial was considerably slower than subsequent trials and this needs to be taken into consideration in the sporting environment. The data shows that FTN and TG are the most robust measures on repeated testing with high ICC values. Although there are statistically significant factors affecting these clinical tests, they would not be expected to impact on the sensitivity of the measures as the differences are small (e.g. <0.12 s). While it is theoretically possible to develop
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reference intervals that reflect BMI and other athlete characteristics (sex, laterality, etc.), the impact of sensitivity is marginalised by the nature of the instrument which is a screen, and designed to minimise and eliminate any false negatives. The data provides clinicians with normative values to use as benchmarks when assessing pathological conditions such as sport-related concussion. These values are based on the mean of three trials and while this remains a more accurate and robust measure of performance, we do acknowledge that it is common for only one measure of each task to be used in a sports setting. As the difference between the first trial and the mean of three trials was only 0.1 s and reliability was high for the first trial, we do not believe this will impact on the sensitivity of the tool. Commercial systems that provide quantitative information and feedback on balance and reaction measures have become increasingly available; however their cost and lack of portability are barriers to clinicians’ access to them.4 There are also concerns that the reliability of the data acquired from these systems may not be accurate due to inherent variability in an individual’s performance.32 In clinical practice, the qualitative aspects of motor performance tests are often assessed rather than speed or timing. For example, in the FTN test features such as the presence of postural and intention tremor and the efficiency of the movements are taken into account. However, despite these tests offering important information to the clinician, they are difficult to interpret and quantify particularly in a sports setting. For these and other reasons, simple, repeatable and reliable tests remain important in clinical practice. From the data in this study, it would appear that FTN and TG are practical and reliable measures of motor performance. While single leg postural stability tests provide clinicians with a method of making bilateral comparisons,26 these measures are not reliable and hence would not be recommended as part of a routine sideline concussion assessment. Limitations of this study include; the majority of the sample being female and right handed and despite this being a normal variance, these norms should be used with caution with left handed males. The fact that the majority of the participants were between 18 and 24 yrs also limits the generalisability of the results to other age groups. Additionally, the sample of convenience and the cross sectional design may introduce a cohort bias. Inter-rater reliability is also an important issue which has not been addressed in this study.
4. Conclusion Normative data were generated for a series of timed motor performance tests that are currently used as measures of coordination and function in the sports concussion assessment setting. Reliability analysis demonstrated that TG and FTN had excellent reliability whereas all SLS conditions were poor. This was most likely due to the considerable individual variability in performance for both SLS tasks. FTN and
TG should continue to be used in test batteries to determine neurological function in sports-related concussion. Further studies should include inter-rater reliability and a population of subjects with impairment of motor function.
Practical implications • Timed dynamic tasks, Finger-to-Nose and Tandem Gait, are practical and reliable measures of motor performance and are recommended for use in concussion assessment tools. • Static single-leg postural stability tests are not recommended for concussion assessment because of poor reliability. • The normative data provides clinicians with a frame of reference to interpret clinical measures when assessing for sport-related concussion.
Disclosure We certify that no party having a direct interest in the results of the research supporting this article has or will confer a benefit on us or on any organisation with which we are associated AND, if applicable, we certify that all financial and material support for this research (e.g. NIH or NHS grants) and work are clearly identified in the title page of the manuscript.
Acknowledgements Supported by the New Zealand Society of Physiotherapists Scholarship Trust Fund and a University of Otago Research Grant.
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A.G. Schneiders et al. / Journal of Science and Medicine in Sport 13 (2010) 196–201 9. Swaine BR, Sullivan SJ. Reliability of the scores for the finger-to-nose test in adults with traumatic brain injury. Phys Ther 1993;73(2):71–8. 10. Feys PG, Davies-Smith A, Jones R, Romberg A, Ruutiainen J, Helsen WF, et al. Intention tremor rated according to different finger-to-nose test protocols: a survey. Arch Phys Med Rehabil 2003;84(1):79–82. 11. Bohannon RW, Leary KM. Standing balance and function over the course of acute rehabilitation. Arch Phys Med Rehabil 1995;76(11):994–6. 12. Frzovic D, Morris ME, Vowels L. Clinical tests of standing balance: performance of persons with multiple sclerosis. Arch Phys Med Rehabil 2000;81(2):215–21. 13. Giorgetti MM, Harris BA, Jette A. Reliability of clinical balance outcome measures in the elderly. Physiother Res Int 1998;3(4):274–83. 14. Kammerlind AS, Larsson PB, Ledin T, Skargren E. Reliability of clinical balance tests and subjective ratings in dizziness and disequilibrium. Adv Physiother 2005;7(3):96–107. 15. Johnston K, Leclerc S, Lacroix V. McGill guideline concussion grading and return to play. Can J Neurol Sci 1998;25(Suppl. 2):S98. 16. Largo RH, Caflisch JA, Hug F, Muggli K, Molnar AA, Molinari L. Neuromotor development from 5 to 18 years. Part 2: Associated movements. Dev Med Child Neurol 2001;43(7):444–53. 17. Bressel E, Yonker JC, Kras J, Heath EM. Comparison of static and dynamic balance in female collegiate soccer, basketball, and gymnastics athletes. J Athl Training 2007;42(1):42–6. 18. Cohen H, Heaton LG, Congdon SL, Jenkins HA. Changes in sensory organization test scores with age. Age Ageing 1996;25(1):39–44. 19. Hageman PA, Leibowitz JM, Blanke D. Age and gender effects on postural control measures. Arch Phys Med Rehabil 1995;76(10):961–5. 20. Madhavan S, Shields RK. Influence of age on dynamic position sense: evidence using a sequential movement task. Exp Brain Res 2005;164(1):18–28. 21. Swaine BR, Desrosiers J, Bourbonnais D, Larochelle JL. Norms for 15- to 34-year-olds for different versions of the finger-to-nose test. Arch Phys Med Rehabil 2005;86(8):1665–9.
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Journal of Science and Medicine in Sport 13 (2010) 196–201
Original paper
Normative values for three clinical measures of motor performance used in the neurological assessment of sports concussion Anthony G. Schneiders a,∗ , S. John Sullivan a , Andrew R. Gray b , Graeme D. Hammond-Tooke c , Paul R. McCrory d a Centre for Physiotherapy Research, University of Otago, New Zealand Department of Preventive & Social Medicine, University of Otago, New Zealand c Department of Medical & Surgical Sciences, University of Otago, New Zealand Centre for Health, Exercise & Sports Medicine, University of Melbourne, Australia
b d
Received 21 September 2008; received in revised form 6 April 2009; accepted 8 May 2009
Abstract Postural control and motor coordination are essential components of normal athletic activity. Tasks involving balance and coordination are used to determine neurological function in sports-related concussion. Determining normative values for these tasks is therefore essential to provide sports medicine professionals with a frame of reference with which to interpret clinical measures obtained from players suspected of sustaining a concussion. One hundred and seventytwo healthy subjects (16–37 yrs) performed three timed tests: Tandem Gait (TG); Fingerto-Nose (FTN); Single-Leg-Stance (SLS) on firm and foam surfaces. Unadjusted geometric means (±SD) for each measure were averaged across three trials. Time to complete TG was 11.2 ± 1.2 s. FTN for the dominant and non-dominant arm were 2.9 ± 1.1 s and 3.0 ± 1.2 s, respectively. SLS values for dominant and non-dominant leg were 20.4 ± 3.0 s (firm), 3.4 ± 1.6 s (foam), and 21.0 ± 2.9 s (firm), 3.3 ± 1.6 s (foam), respectively. For TG, there was an order effect (P < .001) but no age, sex or BMI effects. FTN demonstrated a dominant arm preference (P < .001), sex (P = .006), BMI (P = .043) and order effects (P < .001). SLS demonstrated an order effect on the firm surface (P = .009) and an order (P < .001) and BMI (P = .001) effect on foam. Intra-rater reliability, as measured by ICC (3,3), demonstrated that TG and FTN had excellent reliability compared to SLS. FTN and TG should continue to be used in test batteries to determine neurological function in sports-related concussion. © 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. Keywords: Normal values; Postural balance; Coordination impairment; Reliability; Time
Postural control and motor coordination are essential for normal daily activities1,2 and a crucial requirement for athletic events and activities.3 Maintaining postural equilibrium requires the central nervous system to process and integrate afferent information from the somatosensory, visual, and vestibular systems and execute appropriate and coordinated musculoskeletal responses.4 Impairments in postural control mechanisms, due to disease or injury, are termed postural instabilities and result in motor performance deficits including increased postural sway and poor coordination.3,5 Motor performance tasks involving balance and coordination are used to determine neurological function.6 Static ∗
Corresponding author. E-mail address: [email protected] (A.G. Schneiders).
balance control, dynamic gait execution and upper limb coordination are assessed in individuals presenting with neurological dysfunction due to sports-related traumatic head injury,7–9 where they are often included as standardised components of the screening process. Coordination is usually evaluated by observing the quality and speed of alternating repeated movements1 and the Finger-to-Nose test (FTN) is one of the key components of the neurological examination used to assess this domain.10 Balance tasks are also used as surrogate measures of motor performance. The most common clinical uni-pedal balance task is the Single Leg Stance (SLS), which is often performed under varying conditions (e.g. firm/compliant surface, eyes open/closed) in order to challenge components of the sensory-feedback system.11,12 Gait parameters are also used to determine neurological
1440-2440/$ – see front matter © 2009 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved. doi:10.1016/j.jsams.2009.05.004
A.G. Schneiders et al. / Journal of Science and Medicine in Sport 13 (2010) 196–201
function,8 and Tandem Gait (TG) can be used as a clinical test to assess dynamic balance during locomotion.13,14 While SLS has previously been used to screen for sports-related concussion (SRC),7 the use of FTN in this context has been limited,15 and TG has not been previously used. However, as these tests are commonly used as evaluations of neuromotor function, they have the potential to act as valuable screening items in the assessment of sports-related concussion. It is therefore important that sports medicine clinicians have the ability to quantify motor performance tasks in order to determine function in patients presenting with neurological disorders and the constant ‘time’ can be readily utilised to facilitate this. There is limited normative data available on motor performance tasks despite their widespread use as neurological test instruments.16 The development of norms is important because motor performance can be affected by age and other intrinsic factors.17–20 The establishment of norms could therefore help clinicians distinguish between performances attributable to pathology and those attributable to the normal process of aging or other factors.21 Development of normative data can also improve the objectivity associated with common motor control measurements that assess coordination and balance. This is vital so that sports medicine professionals are able to reliably assess clinical motor performance in order to determine levels of impairment and to plan and evaluate appropriate interventions and rehabilitation. While previous studies have commonly measured clinical balance and coordination in older people,1,13,22,23 limited data are available in younger populations.2 This is particularly important because conditions such as sports-related mild traumatic brain injury (MTBI) often occur in younger populations.24 The Sport Concussion Assessment Tool (SCAT) was developed by McCrory et al.25 following the 2nd International Conference on Concussion in Sport, held in Prague in 2004. The intent was to develop a standardised assessment tool via international expert consensus that could be used globally for sideline assessment of sports concussion as well as for patient education. While many items of the SCAT have been developed and validated for inclusion, the Neurological Screening component of the assessment remains qualitative and limited in its utility. The development of quantitative tools that screen for neurological dysfunction attributable to SRC is an important component of the development of the SCAT which is considered “a work in progress”.25 Tests of motor performance that have been suggested to screen for the neurological component of sports-related concussion include FTN,15 SLS26 and qualitative measures of gait assessment.25 The establishment of norms for these tests will provide sports medicine professionals with a frame of reference to interpret clinical measures obtained from players suspected of a concussion. This could be pivotal in making the correct decision regarding withdrawal of a player from sport and their subsequent triage. It will also provide objec-
197
tive data to assist in assessing and monitoring rehabilitation progress and return to play/sport protocols. The aim of this study was to determine normal values for three timed tests of motor performance for use in the assessment of neurological function in players suspected of sustaining a sports concussion. A secondary aim was to establish the intra-rater reliability of these measures.
1. Methods A prospective cross-sectional design with repeated measures was used for the development of normative values and to determine intra-rater reliability of the selected measures. A sample size of 120 was the absolute minimum required for the calculation of 90% confidence intervals for 5% and 95% non-parametric reference interval limits.27 A convenience sample of healthy male and female subjects aged between 15 and 40 yrs were recruited from high schools, tertiary institutions, and sports clubs in a metropolitan area through advertisements and public notices. Subjects were screened for the following exclusion criteria: recent (<3 mths) musculoskeletal or neurological injuries which could interfere with performance; known neurological, psychiatric, or psychological disease; use of drugs or alcohol that might affect motor tasks; and inability to give informed consent. All subjects gave written informed consent to be involved in the study and ethics approval was obtained from the University of Otago Human Ethics Committee. Data collection took place in a quiet laboratory at a University Research Centre and was conducted by physical therapists instructed in the administration and scoring procedures of the test battery. The sequence of administration of the three tests and their components was balanced by a block randomisation process across subjects to control for potential order effects. Short rest intervals were provided between trials and tasks in order to reduce fatigue and to optimise performance. All trials were completed without footwear. Upper and lower limb dominance was determined by a dichotomous self-report preference survey. Intra-rater reliability of the motor performance measures was assessed by repeating the test using the same examiner 1 week after the initial test. The repeat testing was performed at the same time of day to counter potential diurnal variation. The repeat test order was block randomised to minimise order bias. Each test was demonstrated once by the examiner and participants were then allowed one practise trial to ensure that they could perform the task required. Three trials of each condition were timed with a calibrated stopwatch accurate to 0.01 s (Oregon Scientific, Portland, OR). Subjects who failed a trial (incorrect performance) were required to repeat it. FTN assessed upper limb coordination and speed. The starting position was seated in a chair with a back rest with the test arm outstretched, shoulder flexed to 90◦ , and elbow and index finger extended. The head remained stationary and
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eyes were open. When an audible start signal was given, the subjects performed five successive Finger-to-Nose repetitions using their index finger to touch the tip of the nose as quickly and as accurately as possible. The arm returned to the starting position for completion of the test.28 Subjects failed the test if they did not touch their nose, fully extend their elbow or did not perform five repetitions. Three trials were recorded for each limb. SLS on Floor and Foam was used to measure static balance.29 Subjects were instructed to keep their hands on their hips and their eyes closed. Subjects maintained their balance for as long as possible while standing on their test leg with their eyes closed, on a firm surface and on a foam balance pad (Airex Balance pad, 50-kg/m3 , Alusuisse, CH). A 10 s rest was given between each trial. The test was terminated when the subjects: opened their eyes; touched the floor with their non-test leg; broke contact with the support surface with their standing foot; removed their hands from their hips. Three trials were recorded for each leg and each surface condition. TG was used to measure dynamic balance, speed and coordination.13,14 The subjects began the task standing with their feet together behind a starting line. Subjects walked along a 38 mm wide, 3 m line with an alternate foot heel-totoe gait. Once they reached the end of the 3 m track, they turned 180◦ and returned along the track to the start point.28 Subjects failed the test if they did not maintain approximation between their heel and toe, deviated from the track, or did not turn behind the end of the line. Three trials were recorded. Data analysis was performed using SAS (SAS 9.1.2). Data for all statistical models were log-transformed if marginal and conditional residuals were skewed and geometric means and standard deviations were calculated for each test condition; both for individual trials and for arithmetic mean
performance over all trials. Statistical analyses were based on linear mixed models controlling for age, sex, age-bysex, BMI, and sequence (trials 1–6 for FTN and TG and 1–12 for SLS), with a random subject effect to account for the repeated measures. For TG, foot length and foot width were included, and for FTN, a dominant arm indicator and arm length. A dominant leg indicator, foot length and foot width were included for SLS. Denominator degrees of freedom were determined using Satterthwaite’s approximation. A statistical significance level of P < 0.05 was used for all data. Intra-rater reliability for each measure were computed using the Intra-Class Correlation (3,1) (3,3) (ICC) statistics with the assumption of a random effect for subjects.
2. Results One hundred and seventy-two subjects (F = 110, M = 62) aged 16–37 (mean ± SD, 22.18 ± 3.84) were recruited into the study. Demographic details are presented in Table 1. The mean of each individual trial and the mean of three trials for each motor performance task are shown in Table 2. For FTN, the subject’s first trial was slower than subsequent trials (P < 0.001) however the differences were small and not considered clinically important (<0.09 s), falling within the estimated margin of error when using a hand-held stopwatch. FTN was significantly faster in the dominant/preferred limb (P < 0.001) which equated to a 4% increase in speed. There was evidence that males were 7% faster than females (P = 0.006) and a higher BMI was associated with slower performance times (P = 0.043). For TG there was a significant order effect noted (P < 0.001) which was due to a quicker third trial. Age, sex and BMI were not associated with the time to perform TG.
Table 1 Subject characteristics. Variable
Mean ± SD Females (n = 110)
Range
Mean ± SD Males (n = 62)
Range
Mean ± SD Combined (n = 172)
Range
Age (yr) Mass (kg) Height (cm) BMI Leg dominance Arm dominance
21.6 ± 3.3 62.8 ± 8.5 164.7 ± 6.5 23.1 ± 2.8 14 left 10 left
17–34 42–98 136–180 17–36 96 right 100 right
23.1 ± 4.5 77.1 ± 14.7 178.3 ± 7.8 24.2 ± 3.7 11 left 2 left
16–37 48–130 157–194 19–38 51 right 60 right
22.2 ± 3.8 67.9 ± 13.1 169.6 ± 9.5 23.5 ± 3.2 25 left 12 left
16–37 42–130 136–194 17–38 147 right 160 right
Table 2 Individual trial mean ± SD (geometric) and mean ± SD (arithmetic) of trials 1–3. Time in seconds (n = 172). Measure
Trial 1
Finger-to-Nose (D) Finger-to-Nose (ND) Single Leg Stance Firm (D) Single Leg Stance Firm (ND) Single Leg Stance Foam (D) Single Leg Stance Foam (ND) Tandem Gait
3.0 3.1 13.5 14.5 2.9 2.7 11.3
D = dominant; ND = non-dominant. a Arithmetic mean.
± ± ± ± ± ± ±
Trial 2 1.1 1.2 4.1 3.6 1.8 1.6 1.2
2.9 3.0 16.0 17.6 3.1 3.2 11.2
± ± ± ± ± ± ±
Meana of 3 trials
Trial 3 1.2 1.2 3.5 3.6 1.8 1.8 1.2
2.9 3.0 19.5 17.2 3.4 3.3 11.0
± ± ± ± ± ± ±
1.2 1.2 3.6 3.4 1.80 1.9 1.2
2.9 3.0 20.4 21.0 3.4 3.3 11.2
± ± ± ± ± ± ±
1.1 1.2 3.0 2.9 1.6 1.6 1.2
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Table 3 Intra-class coefficients. Measure
Finger-to-Nose (D) Finger-to-Nose (ND) Single Leg Stance Firm (D) Single Leg Stance Firm (ND) Single Leg Stance Foam (D) Single Leg Stance Foam (ND) Tandem Gait
Intra-rater-same session (N = 172)
Intra-rater–between sessionsa (N = 40)
ICC (single)
ICC (average)
ICC (single)
ICC (average)
0.864 0.863 0.420 0.394 0.195 0.260 0.919
0.950 0.950 0.685 0.661 0.420 0.514 0.971
0.696 0.689 0.142 0.406 0.012 0.000 0.544
0.821 0.816 0.249 0.578 0.024 0.000 0.705
D = dominant; ND = non-dominant. a First trial in each session.
SLS on a firm surface demonstrated an order effect with a first trial that was of shorter duration compared to trials 2 and 3 (P = 0.009) but no significant improvement occurred in SLS time after the second trial. For the foam surface the most significant order effect (P < 0.001) occurred when the firm condition preceded the foam testing. There was no order effect when foam was performed first. Intra-rater reliability of the motor performance measures was assessed by the same examiner both during the same test session and then 1 week following the initial testing. A total of 172 subjects performed multiple trials on the same day and a convenience sample of 40, with comparable demographics (25 F:15 M; age 21.7 ± 2.9; weight 65.7 ± 8.1; height 170.0 ± 7.8; BMI 24.0 ± 8.8), agreed to return and were retested 1 week later. Intra-Class Correlation (ICC) coefficients were calculated for a single point estimate (first trial), and also calculated as a mean of the three trials. The data presented in Table 3 shows that FTN and TG were the most robust measures on repeated testing.
3. Discussion This study is the first to report normative values for timed versions of TG and SLS. FTN data has been reported previously, although in different populations.21 Using similar methodology; Swaine et al.21 reported a mean value of 3.44 s for the right arm and 3.56 s with the left arm for FTN. This study reports values approximately 20% quicker for FTN in a similar age cohort and it is unclear why these values differ given the standardisation of the test and the reliability of the data. One explanation could be that the participants of the two studies were different in terms of physical characteristics including height and mass. In this current study, BMI was shown to be associated with performance as a function of time during the FTN test. However this comparison can not be verified as subject characteristics were not reported by Swaine et al.21 This study demonstrated a gender effect for FTN with males significantly faster than females which does not concur with previous research,1,21,30 however this difference was small (0.12 s) and unlikely to be clinically important in a screening examination. No gender effect was noted for the
postural measures (SLS/TG) in this study, a finding noted in previous studies.19 No age effect was noted for any motor performance measure in this study which was most likely due to the limited age range of the cohort, where over 80% of participants were aged 18–24 yrs. Although motor abilities, including strength, flexibility and coordination, have been shown to decline with age,31 other studies have only demonstrated significant deterioration in balance from the 4th decade.2,31 In this study, a higher BMI resulted in significantly slower performance times on FTN scores and less ability to maintain static balance on an unstable surface. This finding was independent of arm dominance and gender for FTN and has not been previously reported. No clear explanation exists for this finding, but mass dependent inertia of the upper limb may be a factor. The FTN and TG proved to be precise and reliable tests when administered by the same evaluator. These tests can therefore provide a dependable measure of upper limb coordination and lower limb dynamic balance in healthy individuals. There is therefore potential for these tests to be used to neurologically screen for sports-related concussion once they are sufficiently examined for specificity and sensitivity to this condition. The low reliability of the SLS measures may be due to the wide performance variability. Jonsson et al.22 determined that the ability to maintain a static posture during SLS was dependent on a reduced initial decrease in force variability which occurs within the first 5 s of the task, presumably as part of a central balance control strategy. The within and between subject variability in static clinical balance tests is suggested as a hallmark of normal balance performance.32 Another characteristic of motor performance tests is the learning effect that occurs with these tasks.28,29 This study demonstrated that the first trial was considerably slower than subsequent trials and this needs to be taken into consideration in the sporting environment. The data shows that FTN and TG are the most robust measures on repeated testing with high ICC values. Although there are statistically significant factors affecting these clinical tests, they would not be expected to impact on the sensitivity of the measures as the differences are small (e.g. <0.12 s). While it is theoretically possible to develop
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reference intervals that reflect BMI and other athlete characteristics (sex, laterality, etc.), the impact of sensitivity is marginalised by the nature of the instrument which is a screen, and designed to minimise and eliminate any false negatives. The data provides clinicians with normative values to use as benchmarks when assessing pathological conditions such as sport-related concussion. These values are based on the mean of three trials and while this remains a more accurate and robust measure of performance, we do acknowledge that it is common for only one measure of each task to be used in a sports setting. As the difference between the first trial and the mean of three trials was only 0.1 s and reliability was high for the first trial, we do not believe this will impact on the sensitivity of the tool. Commercial systems that provide quantitative information and feedback on balance and reaction measures have become increasingly available; however their cost and lack of portability are barriers to clinicians’ access to them.4 There are also concerns that the reliability of the data acquired from these systems may not be accurate due to inherent variability in an individual’s performance.32 In clinical practice, the qualitative aspects of motor performance tests are often assessed rather than speed or timing. For example, in the FTN test features such as the presence of postural and intention tremor and the efficiency of the movements are taken into account. However, despite these tests offering important information to the clinician, they are difficult to interpret and quantify particularly in a sports setting. For these and other reasons, simple, repeatable and reliable tests remain important in clinical practice. From the data in this study, it would appear that FTN and TG are practical and reliable measures of motor performance. While single leg postural stability tests provide clinicians with a method of making bilateral comparisons,26 these measures are not reliable and hence would not be recommended as part of a routine sideline concussion assessment. Limitations of this study include; the majority of the sample being female and right handed and despite this being a normal variance, these norms should be used with caution with left handed males. The fact that the majority of the participants were between 18 and 24 yrs also limits the generalisability of the results to other age groups. Additionally, the sample of convenience and the cross sectional design may introduce a cohort bias. Inter-rater reliability is also an important issue which has not been addressed in this study.
4. Conclusion Normative data were generated for a series of timed motor performance tests that are currently used as measures of coordination and function in the sports concussion assessment setting. Reliability analysis demonstrated that TG and FTN had excellent reliability whereas all SLS conditions were poor. This was most likely due to the considerable individual variability in performance for both SLS tasks. FTN and
TG should continue to be used in test batteries to determine neurological function in sports-related concussion. Further studies should include inter-rater reliability and a population of subjects with impairment of motor function.
Practical implications • Timed dynamic tasks, Finger-to-Nose and Tandem Gait, are practical and reliable measures of motor performance and are recommended for use in concussion assessment tools. • Static single-leg postural stability tests are not recommended for concussion assessment because of poor reliability. • The normative data provides clinicians with a frame of reference to interpret clinical measures when assessing for sport-related concussion.
Disclosure We certify that no party having a direct interest in the results of the research supporting this article has or will confer a benefit on us or on any organisation with which we are associated AND, if applicable, we certify that all financial and material support for this research (e.g. NIH or NHS grants) and work are clearly identified in the title page of the manuscript.
Acknowledgements Supported by the New Zealand Society of Physiotherapists Scholarship Trust Fund and a University of Otago Research Grant.
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