The truth is that there isn’t a huge amount of good science about them, but most of the anecdotal evidence and the scant amount of research I have seen has suggested that yes, they do help over 5k, especially if you’re doing sub-4:00 min/k. It’s possible that some of this is just the psychological effect of “gearing up in your race gear”. But I don’t think that’s all they can do. Supposedly they help make every step that little bit more efficient, which directly translates not just into reduced energy usage, but into speed. There seems to be a large variance in how much they help depending on the individual and pace, but in general they work better at higher pace.
The truth is that there isn’t a huge amount of good science about them, but most of the anecdotal evidence and the scant amount of research I have seen has suggested that yes, they do help over 5k, especially if you’re doing sub-4:00 min/k. It’s possible that some of this is just the psychological effect of “gearing up in your race gear”. But I don’t think that’s all they can do. Supposedly they help make every step that little bit more efficient, which directly translates not just into reduced energy usage, but into speed. There seems to be a large variance in how much they help depending on the individual and pace, but in general they work better at higher pace.