Gladiator scientist

I read a sci-fi book back in the 70's which (I think) had an educated man/scientist who fought on different worlds in gladiatorial contests. I would say this book could have been written in the 50/60's. I don't think it was the 70's as most of the books I bought in the early 70's came second hand from jumble sales. UPDATE: I think perhaps I'll revise the word Gladiator. The character fought, but it may not be in the sense of an arena. As far as I can remember he was definitely a professor or someone who was highly educated. I'm thinking he fought off-world.

Update: Although I thought the story was identified, It isn't the one. Could this please be viewed and suggestions made. Thanks