Background The worker attended a gym in the morning before starting her shift as a theatre nurse. During her work shift, she claimed to have suffered the gradual onset of lower back pain, radiating into the right leg. The worker brought a claim for compensation pursuant to the Workers’ Compensation and Injury Management Act 1981 (WA) (the Act). Issues The employer disputed liability, arguing that the worker had sustained her injury at the gym. The matter proceeded to a WorkCover arbitration and the worker’s claim was dismissed, with the Arbitrator relevantly finding the worker to be an unreliable witness and concluding that the injury occurred at the gym. The worker appealed, claiming that the Arbitrator applied the wrong legal test in determining whether she sustained an injury pursuant to s. 5 of the Act. She also contended that the Arbitrator erred in law in finding her to be an unreliable witness, in the absence of reliable evidence to support that finding. Decision Goetze DCJ observed that the plaintiff in Hetherington v Amalgamated Collieries of WA Limited [1939] HCA 36, an authority relied upon by the worker, was successful because an underlying condition combined with work caused that worker’s death. His Honour noted that, in the instant case, the employer argued that the work had not affected the worker’s injury suffered at the gym. His Honour noted the medical evidence addressing causation and that the Arbitrator: …found that the contemporaneous records from those health practitioners upon whom Ms Thompson attended contradict her assertion that the injury was work related. His Honour went on to observe that it was open to the Arbitrator to accept the evidence that the injury did not occur at work. In relation to credibility, His Honour held that: It was also open to the learned arbitrator to reject Ms Thompson's evidence as being inconsistent with other proved evidence. Save as noted at [45] below, there is nothing in any contemporaneous record to suggest the initial onset of pain at work. and The findings of fact based on credibility do not involve any error of law. Indeed, it could not be argued that the learned arbitrator found any facts wrongly or that he did so upon any doubtful basis. His reasons are logical. The appeal was accordingly dismissed. Implications of Decision This decision emphasises the importance of fully investigating the background to claims, and ensuring that inconsistencies are brought to the attention of the medical specialists. The decision also highlights the importance of being across the issues and ensuring that applications are made with due consideration to same. Goetze DCJ made a number of observations about how the worker’s lawyer approached the application, and noted that an application to adjourn the appeal had been made but was abandoned at the commencement of the appeal.