Very steep terrain. Some "via ferrata" to hold on to at the steepest points. Possibility of bailing out at the top and taking the cable car back down.
Too steep to run for me..
It's a very well marked trail, starting at Glanegg. Going up-up-up besides some waterfalls. Lots of steep wooden or rock steps, including wires to hold onto at the steepest sections. After reaching the top of the cable car, continue to the next minor peak and then down through tunnels until you reach the Toni Lens Hut. Have a rest at the hut, before continuing towards the Dopplersteig again.
At some point the trail splits into one path continuing slightly down, and one going steeply up -- Don't be tempted to take the easy path down (Kienbergsteig?). I got a bit lost there, as the path and trail markings disappeared. It might work, but you'll end up in Germany. The "correct" path is to go up the steep section towards a saddle, and then join the Dopplersteig down again.