Steep approaches, weighty loads, and full days make climbing in the alpine a serious affair. Likewise, climbers with big alpine goals should take their training seriously. Training for various mountaineering activities is within my weekly schedule. Amongst other training activities, I often go for mountain/trail run. For such training activity, the gear one needs is minimum. A pair of short pants, a T-Shirt, a pair of trail runners and for long distanced a kind of hydration bag.
For training days up to 15k, I usually run without any hydration bag, but if I go for longer distances, especially in summer time, I prefer to have some water with me. In the past I have used various options, but I came to the conclusion that my preferred option is to carry a lightweight hydration bag/vest, and especially the Kalenji Trail Running Bag 10L.