Adrenaline is a well known (and banned due to its effectiveness/danger) military combat drug.
What happens when aliens find out that human bodies produce it naturally when under stress or danger? -- Anon Guest
The V'rithi had known Human Jak as a 'team mom', constantly fretting over their collective wellbeing. Making sure they had rodesnax and clothing that would protect them from the elements. Human Jak was constantly gentle and kind, and -to use a Human phrase- wouldn't hurt a fly.
When the Vorax attacked, it was quite a shock to everyone that Human Jak went Mama Bear and actually threw the Vorax patrol leader at the rest of his crew before picking up the V'rithi transport unit and running away with it. This was also a shock for Human Jak, self-confessed ninety-eight pound weakling.
He had enough time to get the transport unit to safety before setting it down and collapsing in a trembling heap. "Saloop," he panted. "Loads'a sugar. Big cup." This was the traditional aftercare for those suffering an overload of Adrenaline. A soothing beverage loaded with sucrose. In Human Jak's case, a solution of tannin infused with bovine lactate.