Geoffrey Hollow, 70, pleaded guilty in the Victorian County Court to 12 charges including indecent act with a child aged under 16, sexual assault and grooming.
He admitted assaulting seven girls, aged between 11 and 17, while working as a tennis coach in Victoria's far northeast.
Between 2011 and 2022, Hollow took the students aside for supposed strength training sessions, where he would instruct the girls to sit on a makeshift stool made from a bike seat.
He then told them to lift their tops and lower their shorts to "massage" them but his hands would go to their buttocks, hips and thighs.
Hollow also told the girls to wear tight shorts, claiming he bought them for an underprivileged migrant girl and he wanted to see if they would fit.
He then instructed the girls to wear the clothing during tennis training without underwear, telling them to return them back to him so he could wash them.
His offending was uncovered in November 2022 when some of his students disclosed his crimes to a parent who reported it to police.
During a search of his home, police uncovered hundreds of photos of young girls on his devices but they were not deemed to be child abuse material.
In sentencing Hollow in Wodonga on Wednesday, Judge Peter Rozen described the offending as serious and very concerning.
"Parents had entrusted the care of their children to you," the judge said.
"You took advantage of that trust for your own sexual gratification."
Judge Rozen referenced statements from the seven victims, where some described feeling guilt at not reporting Hollow sooner to stop him harming other girls.
The judge reminded the young women they were not to be blamed.
"There is only one person who is responsible for this offending and that is Geoffrey Hollow," Judge Rozen said.
"None of the victims and none of the parents are responsible."
The judge accepted Hollow had pleaded guilty following a sentence indication hearing, sparing the victims the anxiety of giving evidence at trial.
There was no evidence that Hollow had a condition like pedophilia so his risk of reoffending was hard to assess, Judge Rozen said.
But the judge accepted Hollow would not be in a position of power again and specific treatment programs could reduce any risk.
Hollow was sentenced to 12 months behind bars with an 18-month community corrections order, where he will have to complete sex offender treatment.
1800 RESPECT (1800 737 732)
National Sexual Abuse and Redress Support Service 1800 211 028
Kids Helpline 1800 55 1800 (for people aged 5 to 25)
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