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OBJECTIVE	The aim of this study was to evaluate the efficacy of a 9-day accommodation protocol on reducing perceived discomfort while sitting on a stability ball ( SB ) ; trunk muscle activity levels and lumbar spinal postures were also considered .
BACKGROUND	Previous studies have compared SB sitting with office chair sitting with few observed differences in muscle activity or posture ; however , greater discomfort during SB sitting has been reported .
BACKGROUND	These findings may indicate an accommodation period is necessary to acclimate to SB sitting .
METHODS	For this study , 6 males and 6 females completed two separate , 2-hr sitting sessions on an SB .
METHODS	Half the participants completed a 9-day accommodation period between the visits , whereas the other half did not use an SB during the time .
METHODS	On both occasions , self-reported perceived discomfort ratings were collected along with erector spinae and abdominal muscle activity and lumbar spinal postures .
RESULTS	Discomfort ratings were reduced in female participants following the accommodation ; no effects on muscle activation or lumbar spine postures were observed .
CONCLUSIONS	Accommodation training may reduce perceived low-back discomfort in females.Trunk muscle activity and lumbar spine postures during seated office work on an SB did not differ between groups ; however , greater sample power was required to conclusively address these variables .
CONCLUSIONS	Regarding whether to use an SB in place of a standard office chair , this study indicates that females electing to use an SB can decrease discomfort by following an accommodation protocol ; no evidence was found to indicate that SB chair use will improve trunk strength or posture , even following an accommodation period .

