Eventually the scuffling duo ended up on the floor where the younger man got the upper hand, putting the victim in a headlock.
CCTV footage of the incident shows Hona try to get to his feet but he is eventually dragged to the ground again.
As the fight progresses, they move out of view of the cameras before the defendant emerges, puts some clothes back on and returns to work.
He told co-workers that he had left Hona unconscious on his back and when they arrived at the gym he was unresponsive.
The father of seven was pronounced dead at 2.30pm after unsuccessful CPR efforts.
It is understood Hona was overweight and had an enlarged heart among other health difficulties.
Sentencing will take place next month.
The maximum penalty for manslaughter is life imprisonment.
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