Article Text

Download PDFPDF

The effect of exercise on motor performance tasks used in the neurological assessment of sports-related concussion
  1. A G Schneiders1,
  2. S J Sullivan1,
  3. P R McCrory2,
  4. A Gray3,
  5. S Maruthayanar1,
  6. P Singh1,
  7. P Ranhotigammage1,
  8. R Van der Salm1
  1. 1
    Centre for Physiotherapy Research, University of Otago, Dunedin, New Zealand
  2. 2
    Centre for Health, Exercise and Sports Medicine, University of Melbourne, Victoria, Australia
  3. 3
    Department of Preventive & Social Medicine, University of Otago, Dunedin, New Zealand
  1. Anthony G Schneiders, Centre for Physiotherapy Research, School of Physiotherapy, University of Otago, PO Box 56, Dunedin 9054, New Zealand; tony.schneiders{at}otago.ac.nz

Abstract

Sports-related concussion is assessed using both cognitive and motor performance tasks. There is limited understanding of how exercise affects these measures. The purpose of this study was to investigate the effect of moderate-intensity exercise on three selected measures of motor performance.

A repeated measures design was used to compare baseline motor performance scores with post-exercise scores with an exercise intervention modelled on the physiological demands of a team sport. 30 physically active subjects performed timed motor performance tasks: Finger-to-Nose (FTN), Tandem Gait (TG) and Single Leg Stance (SLS). The tasks were administered twice pre-exercise and twice post-exercise.

FTN, TG and SLS demonstrated high test–retest reliability (ICC values >0.8). 15 minutes of moderate-intensity exercise caused a significant improvement in FTN (T2 = 2.66 (SD 0.38), T3 = 2.49 (0.32); p<0.001) and TG (T2 = 13.08 (2.84), T3 = 12.23 (2.22); p = 0.001), but not in SLS (T2 = 5.94 (4.99), T3 = 5.91 (5.54); p = 0.507).

Improvement in the performance of motor tasks after exercise has implications for the immediate assessment of sports-related concussion, given that measures of motor performance are utilised in concussion assessment instruments.

Statistics from Altmetric.com

Request Permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

It is estimated that approximately 300 000 sport-related concussions occur in the United States annually.1 Athletes who are suspected of being concussed need to be screened by sideline sports medicine personnel to determine appropriate medical management.2 3 Commonly reported physical signs of concussion include impaired coordination, unsteady gait, and poor balance.2 3

Instruments such as the Sport Concussion Assessment Tool,3 Standardised Assessment of Concussion,2 Balance Error Scoring System4 and the McGill Abbreviated Concussion Evaluation5 are sideline screening instruments used in the assessment of concussion that utilise motor performance measures to assist diagnosis. It is essential that assessment tools are reliable, easy to use in an athletic population, and scientifically valid. Moreover, it is critical to know how exercise affects these measures. If exercise adversely alters task performance, this could result in incorrect decisions being made concerning an athlete’s injury status and compromise return to play protocols.

The aim of this study was to determine the effect of moderate-intensity exercise on measures of motor performance utilised in the neurological examination of athletes suspected of having sustained a concussion. A secondary aim was to determine the reliability of these measures.

METHODS

Subjects

A cohort of physically active tertiary students with no known neurological, musculoskeletal, or cardiovascular conditions volunteered. All subjects gave written informed consent and were screened with the Physical Activity Readiness Questionnaire.6 The study procedures were approved by the University of Otago Human Ethics Committee.

Design

A repeated measures design with an exercise intervention was used. The mode and intensity of exercise were selected to mimic the physiological demands of a team sport.

Procedure

All tasks were performed in a laboratory on solid wooden flooring and SLS on Foam required an additional closed-cell foam surface (Airex, Alusuisse, CH). Subjects dressed in their usual athletic attire, identified their dominant hand and leg and were briefed on the motor performance measures and exercise protocol. Practice of each measure was allowed up to three times. Three trials of each measure were repeated at four 15 minute intervals (T-1,2,3,4). All measures were timed using a stopwatch accurate to 0.01 s. The task order was randomised to avoid order bias.

Measures

The assessment of motor performance followed standardised protocols.7

FTN measured upper limb coordination and speed. The starting position was supported sitting with the dominant arm outstretched, shoulder flexed to 90° and the index finger pointed. The head remained stationary and eyes were open. When the start signal was given, the subjects performed five successive FTN repetitions using their index finger.

TG measured dynamic balance, speed and coordination.8 9 The subjects began the task with their feet together behind a starting line. Subjects walked along a 38 mm wide, 3 m line with an alternate foot heel-to-toe gait, turned 180° behind the end of the line and returned to the start.

SLS on Floor and Foam was used to measure static balance. Subjects maintained their balance to a maximum of 30 s while standing on their dominant leg with their eyes closed on firm (SLS Floor) and foam surfaces (SLS Foam). Subjects were instructed to keep their hands on their hips and their eyes closed. A rest was given between trials (10 s).

Exercise protocol

The intervention consisted of four stations with immediate transitions involving upper and lower-body exercise that simulated the physiological demands of a rugby game.10 11 Station 1 comprised a 3 minute exercycle (Monark 818e, Stockholm, SE). Station 2 consisted of 4 minutes’ arm cranking (Monark 881, Stockholm, SE), followed by 4 minutes’ treadmill (Quinton Medtrack, Rochester, NY) running (Station 3). Station 4 comprised 4 minutes of rowing (Concept II, Morrisville, VT). To standardise exercise intensity to a sport-specific level, 75–85% of APMHR was used.10 11 Heart rate was recorded using a Polar-F1 monitor (Gays Mills, WI). Subjects quantified their rate of perceived exertion (RPE), using a 15-point (6–20) Borg Scale.12

Statistical analysis

An a priori level of significance of 0.05 was used and the data were analysed using linear mixed models with a random subject effect to account for correlations within time points and within subjects. The data were examined for skewness of the residuals and where necessary a log transformation was applied. Intra Class Correlations (ICC) were computed for the pre-exercise trials with the assumption of a random effect for subjects. All statistical procedures were performed using SAS 9.1.2.13

RESULTS

Thirty physically active subjects (15 male: 15 female) aged 18–25 years (mean (SD) 20.8 (1.3)) were recruited (table 1). All subjects were right-hand dominant and 15 women and 12 men demonstrated right-foot dominance. All subjects achieved the target exercise intensity.

Table 1 Subject characteristics

Reliability

ICCs were calculated for mean values. Reliability was “good” for FTN (ICC  = 0.94), TG (ICC  = 0.98), SLS Floor (ICC  = 0.85) and SLS Foam (ICC  = 0.85).14

Due to the high number of subjects who achieved the 30 s threshold, the SLS Floor task was not suitable as a continuous variable in a linear model and was removed from further analyses.

FTN: there was a gradual decrease (improvement) in FTN mean scores over the first three trial time points (table 2).

Table 2 Summary data and analysis of the Finger-to-Nose task

TG: the data demonstrated a steady decrease (improvement) in mean TG scores over all trial time points (table 3).

Table 3 Summary data and analysis (log transformed) of the Tandem Gait task

SLS Foam: the data demonstrated a significant improvement in performance between the first and second trial time points (table 4).

Table 4 Summary data and analysis of the Single Leg Stance (Foam) task

There was an increase in performance from baseline in all tasks prior to exercise that continued post-exercise for FTN and TG and then plateaued (fig 1). SLS did not improve immediately post-exercise but did improve 15 minutes after exercise.

Figure 1 Absolute percentage (%) mean change from baseline (T1) for Finger-to-Nose (FTN), Tandem Gait (TG) and Single Leg Stance (SLS).

DISCUSSION

The findings indicated that 15 minutes of moderate intensity exercise facilitated performance of FTN and TG tasks. The data demonstrated an improvement in performance prior to exercise in all measures, which might suggest the presence of a learning effect. Learning effects have been previously associated with the performance of SLS tasks15 16 and can reduce the reliability of performance tests.17

In this study there was no evidence to suggest a significant decrease in balance performance following exercise, which is inconsistent with the findings of previous studies.1820 Differences in exercise mode and intensity between studies might account for this.

Limitations of this study include the single measure of exercise intensity, the narrow age range of the subjects, and that the study was conducted in a laboratory setting. All these factors limit the generalisability of the results.

CONCLUSION

Current management guidelines utilise motor performance as a surrogate measure of neurological function in the assessment of concussion. The study demonstrated that moderate-intensity exercise had a significant effect on these measures. These findings need to be taken into account in the assessment and management of concussion.

What is already known on this topic

  • Athletes suspected of being concussed are screened by sideline sports medicine personnel to determine appropriate medical management.

  • Current concussion management guidelines utilise motor performance tasks as surrogate measures of neurological function.

  • Physical activity can affect the performance of these measures.

What this study adds

  • This study demonstrated that moderate-intensity exercise facilitated performance of dynamic balance and coordination tasks.

  • There was no evidence to suggest a significant decrease in static balance performance following exercise.

  • These findings need to be taken into account in the assessment and management of sports-related concussion.

REFERENCES

Footnotes

  • Competing interests: None declared.