See the bottom of this thread https://www.duolingo.com/comment/3859133
As it said, verbs of motion can use either hebben or zijn depending on the sentence context. If emphasis is on the action (such as this sentence), then hebben would be used. If emphasis is on where the action is going (for instance, if the sentence was "You walked to the station"), then zijn would be used (Jij bent naar het station gelopen).
Hardlopen is all running as a sport or recreational, anything faster than walking qualifies, e.g. Ik loop ieder weekend een uur hard (I run for an hour every weekend). The verb joggen (loanword from English) is also used for recreational running (not for the sport or serious training for the sport).
Rennen is basically running in all other circumstances, e.g. Ik moet altijd rennen om de trein te halen (I always have to run to catch the train).
You can think of it that way, but it's also used in general for participants in any kind of running competition (including sprints), not just when there is need for a short term (like your example of warning your group of runners for another runner). Also it's normal to say things like ik loop de 400 meter, this clearly involves running and not walking.
What I mean is: after walking for several hours (but before stopping) you might be told by your fellow hiker you've been walking for a long time! which is different from you were walking for a long time (that day in the past). You have walked for a long time could be what they tell you after finishing the hike. So my question is: given that jij was een lange tijd aan het lopen sounds to me more like you were walking for a long time than anything else to me, does the English nuance of perfect continuous really not correspond to (at least one of the) meaning(s) of jij hebt (een) lange tijd gelopen?
Hallo! Ik heb wat hulp nodig :)
I thought that words whose 'stems' end in: p, t, k, s, f, ch ...
... would have a "past participle" using this combination: ge + stem + t
hopen - hoop - gehoopt koken - kook - gekookt missen - mis - gemist
Why is this not the case with 'loop'?