Darren Manaog Penaredondo, 28, died in General Trias city, on the outskirts of the capital Manila, on April 3 - two days after he was caught by police buying a bottle of water from a local shop after the 6pm curfew.
Partner Reichelyn Balce said he and a group of other curfew-breakers were forced to do 100 squat thrusts - but had to repeat the exercise if they failed to do it in unison.
By the time Mr Penaredondo arrived home the following morning, Ms Blace said he had performed 300 of the exercises and was barely able to walk.
'When he came home on Friday, around 8am, he was assisted by a fellow quarantine violator who was arrested with him,' Ms Balce told local news site Rappler.
'I asked if he was beaten up. He just smiled but it was obvious he was in pain.'
Ms Blace said he was unable to stand for the rest of the day, and was crawling across the floor because his legs and knees hurt so much.
Then, while trying to use the bathroom, Mr Penaredondo began suffering seizures and had to be revived by a neighbour using CPR.
He regained consciousness for a short time afterwards, but eventually passed away around 10pm without ever reaching hospital.
Cousin Adrian Lucena announced the death on Facebook, writing: 'We love you so much. We will not allow those responsible to escape justice.
'Sorry I can't go home because of these times. I love you so much.'
Rodolfo Cruz Jr, head of local village guard units, confirmed that Mr Penaredondo was arrested for breaching curfew on the night of April 1 - but said he was handed over to municipal police shortly afterwards.
Lieutenant Colonel Marlo Solero, head of the local police force, denied that squats are used as a punishment for curfew violators and said officers are supposed to give lectures to rule-breakers.
If police are found to have ordered Mr Penaredondo to do squats then it will not be tolerated, he added.
Mayor Ony Ferrer released a statement on Facebook as news of the death spread, pledging to carry out a full investigation.
'We want to know what really happened for the family’s sake,' he said.
He added that he had been in contact with Mr Penaredondo's family to offer his condolences.
It comes as Rodrigo Duterte extended a lockdown by another week after an alarming spike in coronavirus infections in the Philippines.