The 36-year-old represented the Kingdom in taekwondo at the 2016 Summer Games in Rio before switching to cross country skiing for the 2018 Winter Olympics in South Korea.
In May, Taufatofua announced he was taking up kayaking in a bid to become the first person this century to compete in three different Olympic sports.
However, the Brisbane-based athlete tore his serratus muscles during training last week, while pushing for a new speed record, causing sharp pain along his side and lower ribs.
"For close to five months in this camp I haven't missed a day of training and am in the best condition of my life," he wrote in a post on social media.
"Normally before a competition an athlete will taper off. I decided not to taper but to ramp up my training to hit a speed bench mark. I've been running on the fence between improving rapidly in a new sport and pushing a limit to see what my body could take and how fast I could improve.
"My balance had finally gotten better and so I decided to push for speed. In the last three weeks I went from 8km/hr in a race kayak to a PB (personal best) of 19.2km/hr. I was targeting 21+ km/hr by race day to be competitive and so I pushed harder.
"During a sprint session my body decided to push back and I've ended up with a torn muscle and rib injury. Not the worst injury I've had but definitely one of the more painful and inconvenient in terms of timing."
With the Canoe Sprint Oceania Championships beginning in Penrith, west of Sydney, next weekend and the Oceania Taekwondo Qualifiers on the Gold Coast at the end of the month, Taufatofua said he had been unable to bend, twist or hold his core and was holding off paddling and kicking to see if the pain could subside.
But whatever happened, he insisted that he would be on the starting line in Penrith one week from now and would give it his all out on the water.
"We have been strategising how best to proceed," he said. "Other than the injury I am in the best physical and mental condition of my life. I didn't fall out of my kayak 1000 times into a bull shark river just to stop.
"In times like this, I go to prayer for help beyond what I can do alone. My spirits is high and we are doing all we can to maintain my condition while I heal.
"Come competition day, whatever happens with the injury or the pain, I will be in the kayak on that starting line and will hold nothing back, rib or no rib...whatever I have left I will give."