Proceedings of The Physiological Society
University of Oxford (2011) Proc Physiol Soc 23, PC199
The effect of an exercise ball on trunk muscle responses to rapid limb movement
H. Weaver1, D. Vichas2, P. H. Strutton2, I. O. Sorinola1
1. Academic Department of Physiotherapy, Division of Health and Social Care, King's College London, London, United Kingdom. 2. The Nick Davey Laboratory, Human Performance Group, Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, United Kingdom.
Anticipatory postural control is a key component of human movement and has been shown to be significantly impaired following disorders of neurological (Dickstein et al., 2004) and musculoskeletal systems (Hodges & Richardson, 1996). The use of exercise balls is widely advocated as an aid to facilitate improvements in postural control in patients with trunk muscle weakness, but its effect on anticipatory postural control has received little attention. This study compared the latency and amplitude of trunk electromyographic (EMG) activity in response to limb movement when seated on an exercise ball or on a chair in sixteen healthy, moderately active human subjects. At the sound of an auditory cue, the subjects carried out either hip flexion or arm flexion (unilateral or bilateral), with or without weights, as fast as possible, while sitting on an exercise ball or a standard chair. The latency and amplitude of EMG activity were recorded from selected trunk muscles: erector spinae (ES), external obliques (EO), internal obliques (IO), rectus abdominis (RA) and either an upper limb muscle (deltoid) or a lower limb muscle (rectus femoris). There were minimal differences in amplitudes of EMG activity in any of the trunk muscles between the conditions (ball or chair) following the upper limb movements. These results suggest that there is no benefit in simple arm flexion movements whilst seated on the exercise ball in comparison to a chair. The amplitude of the RA (p< 0.05), EO (p<0.01) ipsilaterally and IO (p <0.05) bilaterally was significantly higher on the ball in the weighted hip flexion protocol. In addition, there is some suggestion of early activation of RA and EO muscles in the weighted hip flexion condition. These results indicate that hip flexion activity while seated on a gym ball elicits earlier anticipatory postural activities while upper limb flexion does not. This result may have implications for rehabilitation of postural and movement deficits in people with conditions such as stroke.
Where applicable, experiments conform with Society ethical requirements