85 Sports concussion assessment: the effect of exercise on dynamic and static balance A. G. Schneiders 1 , S. J. Sullivan 1 , P. Handcock 2 , A. Gray 3 , P. R. McCrory 4 1 Center for Physiotherapy Research, University of Otago, Dunedin, New Zealand, 2 School of Physical Education, University of Otago, Dunedin, New Zealand, 3 Department of Preventive & Social Medicine, University of Otago, Dunedin, New Zealand, 4 Center for Health and Exercise Sports Medicine, University of Melbourne, Vic., Australia Corresponding author: Anthony G. Schneiders, School of Physiotherapy, University of Otago, PO Box 56, Dunedin 9054, New Zealand. Tel: 164 3 479 7460, Fax: 164 3 479 8414, E-mail: tony.schneiders@otago.ac.nz Accepted for publication 25 March 2010 This study determined the effect of exercise on measures of static and dynamic balance used in the assessment of sports- related concussion (SRC). A balanced three-group cross-over randomized design was used with three levels of exer- cise verified by blood-lactate, heart rate and ‘‘perceived- exertion’’: no exercise/rest (NE), moderate-intensity exercise (ME), and high-intensity exercise (HE). Participants per- formed two timed balance tasks: tandem gait (TG) and single-leg stance (SLS); pre- and post-exercise and 15 min after exercise. Linear mixed-models with adjusted means and contrasts compared exercise effects. Ninety asymptomatic participants (45<:45,) were recruited. When times were contrasted with NE; HE resulted in a significant decrease in SLS (Po0.001) and TG (Po0.001) performance imme- diately following exercise. Fifteen minutes of recovery improved SLS (Po0.001) and TG (P 5 0.011) from post- exercise performance. ME caused a significant decrease in performance in SLS (P 5 0.038) but not TG (P 5 0.428). No statistically significant change occurred following ME in any tasks after 15-min recovery (SLS P 5 0.064; TG P 5 0.495). Test–retest reliability was considerably higher for the dy- namic task compared with the static task. The reliability of static and dynamic balance tasks, and the change in perfor- mance following exercise, have implications for the immedi- ate assessment of SRC, as these measures are utilized in concussion assessment instruments. Various clinical balance assessment tools are used in the sports medicine setting to assess diverse aspects of neurological function, including proprioceptive deficits following lower limb musculo-skeletal injury (Nakagawa & Hoffman, 2004; Wikstrom et al., 2005; Docherty et al., 2006) and the effect of concussion on postural control mechanisms (Guskiewicz, 2003). One of the most widely used measures is the Balance Error Scoring System (BESS) (Riemann et al., 1999), which has be utilized as a standalone tool as well as being incorporated into multi-modality assessments such as the Sports Concussion Assessment Tool2 (SCAT2) (McCrory et al., 2009). The BESS was originally developed as an objective sideline assessment tool for the evaluation of pos- tural stability in athletes (Guskiewicz, 2001), and has since been promulgated as a tool to assess balance deficits associated with sports concussion (Riemann et al., 1999; Guskiewicz, 2003). The full BESS test battery consists of six testing conditions that use three static stances (double leg, single leg, tandem) on two surfaces (firm, foam). While the BESS, particu- larly single-leg firm-stance (Finnoff et al., 2009), has been shown to be reliable in controlled laboratory environments (Riemann et al., 1999; McLeod et al., 2004), its role in the on-field situation may be compromised either by the effects of the physical environment (Onate et al., 2007), or exercise and fatigue as a consequence of sports participation (Susco et al., 2004; Wilkins et al., 2004; Fox et al., 2008). While exercise has been suggested to have a deleterious effect on static balance tasks, a recent study demonstrated that a dynamic balance and coordination task [tandem gait (TG)] was a more robust and resilient measure in a controlled exercise setting (Schneiders et al., 2008). Despite this finding, the effect of exercise on static and dynamic clinical balance measures remains uncertain as limitations of previous studies have included either: low subject numbers, no calculation of sample size, limited follow-up periods, no control groups, or only single modes of exercise (Susco et al., 2004; Wilkins et al., 2004; Fox et al., 2008; Schneiders et al., 2008). It is essential that any side-line assessment tool used in medical screening is simple, reliable, easy to use in an athletic population, and scientifically valid. If exercise adversely alters task performance in a Scand J Med Sci Sports 2010 & 2010 John Wiley & Sons A/S doi: 10.1111/j.1600-0838.2010.01141.x 2012: 22: 85–90