Map makers are currently not able to disallow player movement completely. Players are still able to move by sprint jumping (Default Keys: Ctrl+W+Space) even when the effects 'Slowness' and 'Jump Boost' 128 are active (Jump Boost 128 negates jump). Instead of using Jump Boost you can also set generic.movementSpeed to 0 using attribute modifiers

Slowness (using /effect):

/effect @p 2 100 10 true

Slowness (using attribute modifiers):

/replaceitem entity @p slot.armor.feet leather_boots 1 0 {AttributeModifiers:[{Operation:0,UUIDLeast:1,UUIDMost:1,Amount:-0.1,AttributeName:generic.movementSpeed,Name:Freeze}]}

Jump Boost:

/effect @p 8 100 128 true

Disallowing the player to sprint if the player is not able to move at all would allow map makers to freeze players completely.