Below, an interesting survey about the benefits of cross training. K.Grovdal, J.S’s Norge neighbor, 4:05/8:37/14:51/31:13 (30:32/road) uses this, and limits her running to one hour a day max.
Source: Jon Arne Glomsrud (from the thread re. K.G.)
“ The rule of specificity applies in running, but I guess we don't know how much is needed. Obviously running needs a great aerobic general capability and also a superb running economy. Running economy comes from great form, efficient stretch shortening reflex mechanisms but also great aerobic endurance of the specific running muscle fibers. I don't know how compatible xc skiing muscle fiber activation is to running, but it should be much better than cycling, that is for sure. The general aerobic capability is for sure trained very well in xc skiing, where even more muscle mass is used requiring even more from the heart and lung function.
Karoline has been a great runner for so long that skiing just is a great way to stay injury free and unlock her aerobic capability. Her running economy is already superb.
I think there are many examples of people that can run really fast on a limited milage. Is there some scientific or coach experience that 50-60min running is enough to give close to max running economy adaptations?
If that is true there should be no reason for elites not cross training with a relevant and low impact training form at least 1-2h a day in addition. Triathletes run impressively fast and for instance Blummenfelt or Iden have expressed that in case going only for running fast they would maybe hit 100-120mpw + adding cycling to max out on volume. Not everyone can handle even 100mpw of running and then the only option would be to cross train to proper volume. I also see discussions on this forum that master runners should increasingly use low impact cross training to keep the volume up and adapt to longer muscular recovery needs between running workouts.
I do two days a week almost running free at 50 years of age, doing cycling. I don't need to go at a recovery intensity though as the muscular recovery is great just by not running that day. So a good easy or even moderate pace is fine, increasing the aerobic training impact.
For running I see people doing xc skiing, cross training/elliptical machines, cycling, aqua running. Cycling might be the least effective, but still great” end quote from Mr Glomsrud.
Food for thought, the Wizard? Difficult to cross train in Kenya due to economic difficulties and the lack of alternatives but for his western athletes definitely possible.