Combat speed is how fast a character can fight, not how fast a character can run during combat. To say that character A has normal human travel/movement speed (because movement speed is what travel speed is intended to describe), but infinite combat speed means his punches, kicks, and dodging movements are infinite, but he can't run at that speed. To say that character's running/travel speed changes solely dependent on them being in a fight (without that being a specific verse mechanic or power) is ridiculous.
This misconception is extremely pervasive— especially after Screwattack's Goku vs Superman. People on Goku's side tried to claim that Goku's faster than what they calced. He is. But their reasoning was because Goku can move (as in Do the teleporting speed thing he does) faster during combat. "Short Burst speed". No. That's not true. It makes no sense. To say Goku couldn't have used that speed to do anything else besides fighting— to say that Goku can only run or fly or vanish from sight as fast as he does when he is fighting is ridiculous.
No. These people are wrong. They tried to argue that Goku and DBZ characters had been pacing himself to not burn himself out when he flew (which doesn't make any sense for several reasons), and that doesn't change what his actual movement/travel speed is, nor is their argument that Goku can't sustain that speed of long periods justified. Snake way, Goku wasn't going to Pace himself. He wanted to fly back as fast as possible to save his friends— and even then, Karin gave him senzu BECAUSE he was tired from moving full speed to get there. The whole thing is PIS, because we see characters outpace their energy beams, like Goku did against Piccolo, or against Cell's Kamehameha— in addition to them being able to hit each other by flying at each other and running at each other full speed.
Point is;
Movement Speed/Travel Speed: How fast a character can move their entire body from point A to point B, whether it's a small hop or a sprint.
Combat speed: A combination of attack speed and reaction speed sustained over a fight. AKA how fast a character can move their limbs, or body parts, typically during a fight.
Example:
Usain Bolt and Bruce Lee are in a fighting ring that is the same size as the DBZ fighting tournament arenas.
Bruce Lee has superior combat speed. Usain Bolt has superior movement/travel speed. Bruce can Blitz Bolt.
Why?
Because Bruce has faster combat speed.
How?
Bruce will never catch up to Bolt running around. Just because Bruce can punch fast, pick up his legs to dodge a sweep faster than Bolt, Duck under a punch and stand back up faster than Bolt, it doesn't mean he can run as fast as Bolt. This doesn't magically change when Bruce and Bolt are about to fight. He blitzes, however, when the fists fly, Bruce's fists fly far faster than even Bolt can see, hitting him too fast for him to react, Blitzing.