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TRAINING DYNAMIC BALANCE
training (TRD), significant improvements in dynamic balance performance occurred in all directions of the SEBT. In the UTD leg, some small but significant improvements in reach were recorded that were suggestive of a crossover training effect. In the CON group, SEBT performance did not change over the 4 weeks of the intervention. The performance of both groups pre-intervention were similar to data published in past research (9), and any small differences were probably due to fitness and health status differences between cohorts. The improvements seen in the trained limb of the subjects following 2 weeks and 4 weeks of the balance- training programme appear to be broadly consistent with other studies involving a range of different balance- training/assessment programmes for individuals with a functionally stable ankle, over longer periods of time (5,6,10). Although there were significant
improvements in total combined and all individual direction reach scores, it is pertinent to note some disparity in the percentage change from pre- to post-training. Interestingly, the smallest improvement (approximately 11%) was observed in the anterior direction and the largest improvement (approximately 36%) was witnessed in the anterolateral direction. Whether these changes reflect a ‘‘specificity bias’’ in the training movements employed is not clear. It is, indeed, unclear whether there is a requirement to balance train in all directions or even to assess balance ability via the SEBT in all directions (11).
There are a number of possible mechanisms that could account for the improved balance performance in the current study: n Improved control over centre of gravity shifts, although without data from a force plate we can only speculate about this factor n Improved automatic postural response patterns: Sveistrup and Woollacott demonstrated improved automatic postural response patterns including increases in the probability of activating functionally appropriate muscles following a 5-day perturbation training programme (12); Wiley and Damiano also suggested that balance training may serve to improve neural
TABLE 1: EXAMPLE OF DYNAMIC SINGLE-LEG BALANCE TRAINING PROGRESSION Floor Gymnasium floor
Eyes Open
Exercise
60 second exercise trial in single-leg balance position; contralateral leg held in relaxed position with minor knee and hip flexion by side of test leg; five trials with 30 second rest between trials
Gymnasium floor Soft gymnasium mat Soft gymnasium mat Gymnasium floor
Closed Open Closed Open
As above As above As above
60 second exercise trial in single-leg balance position; contralateral leg held in comfortable relaxed position with minor knee and hip flexion; trunk then rotated smoothly to end of range in both directions; five trials with 30 seconds rest between trials
Gymnasium floor Soft gymnasium mat Soft gymnasium mat Gymnasium floor
Closed Open Closed Open
As above As above As above
60 second exercise trial in single-leg balance position; contralateral leg held in 90° hip and knee flexion; trunk then rotated smoothly to end of range in both directions; five trials with 30 second rest between trials
Gymnasium floor Soft gymnasium mat Soft gymnasium mat
Closed Open Closed
output in response to postural disturbances (13) n Attention, defined as the process by which the central nervous system acts upon proprioceptive information perceived as being relevant: it is possible that balance exercises increase the attention paid to proprioceptive cues by the brain, first at the conscious level early in training, and then later, perhaps after more training, at the autonomous level (14). If this represents a central processing adaptation rather than just a peripheral cue sensitisation, then this may have some applicability to the current data. The improvements observed in the UTD leg in the current study provide some indirect support for a central processing role that could improve both TRD and UTD legs performance in the reach trials.
An increase in muscle strength
may contribute to the increased reach scores attained after training, although Chandler and colleagues demonstrated no significant relationship between strength gains and balance measures in their training study of college students (15).
9
As above As above As above