Seems like Onoda already surpassed both of them.
He was following them all throughout the race and seemed less tired despite being fatigued from the race.
@sleepyknight
He just carried Imaizumi, Ashikiba and Shinkai to the 500m mark to the goal on the afternoon of the same day as this race.
He was visibly tired after that and he already recovered enough to be able to keep up with them? There's no way it's just stamina.