Why descents are dangerous
A summit day looks symmetric: you climb up, you climb down. The physiology is anything but. On the way up, your muscles contract concentrically - they shorten under load, doing classical work. On the way down, they contract eccentrically - they lengthen under load, absorbing your bodyweight against gravity. This is a fundamentally different kind of stress, and the body handles it differently (LaStayo et al., 2003).
Eccentric load damages muscle fibres at a far higher rate per unit of effort than concentric work. That is why your quads are toast after 1500m of descent but feel fine after 1500m of ascent. It is also why most overuse injuries on alpine routes happen on the descent - knee pain, IT band issues, ankle rolls under fatigue, slips on tired legs.
If you train only the up-leg of mountaineering, you arrive at the summit prepared and at the trailhead destroyed. The descent has to be its own training stimulus.
Eccentric vs concentric: the actual difference
Picture a squat. As you stand up, your quads contract and shorten. That is the concentric phase. As you lower back down, your quads contract and lengthen, controlling the descent. That is the eccentric phase. Same muscle, same movement, two different physiological loads.
Three things make eccentric work distinct:
- Higher force per unit effort. Eccentric contractions can produce roughly 1.3 times the force of equivalent concentric ones (Lieber & Friden, 2002). You can handle more load eccentrically than you can lift concentrically.
- More micro-damage to muscle fibres. The lengthening under load disrupts sarcomere structure more aggressively. Hence the pronounced delayed-onset muscle soreness (DOMS) 24-48 hours later.
- Slower recovery. Eccentric work takes longer to recover from than equivalent concentric. Plan accordingly: do not do an eccentric block 48 hours before your long climb.
If you trained only the climb, you arrive at the summit ready and at the trailhead broken. The descent has to be its own block.
The exercises that actually work
You do not need a gym for this. The most effective exercises for mountain descent are mostly bodyweight or lightly loaded. Pick two or three to rotate through your week:
Reverse step-downs
Stand on a 30-50cm box. Slowly lower one foot to the floor over 4-5 seconds. Touch lightly. Push back up to standing. 3 sets of 8-10 per leg, twice a week. The slow lowering is pure eccentric work for the quad and glute.
Downhill running or hiking
A 20-30 minute moderate downhill run at zone 1-2 effort, once a week. The classic specific stimulus. Start with 10 minutes if new to it - DOMS will surprise you. Build slowly. Vogt & Hoppeler (2014) showed targeted downhill running improves descent tolerance within 4-6 weeks.
Slow tempo squats
Squat with a 5-second descent, 1-second hold at the bottom, normal-pace ascent. 3 sets of 8 with bodyweight or light dumbbells. The concentric is incidental; the eccentric is the work.
Backward walking on a treadmill incline
Counter-intuitive, but useful. Walking backward up a 10 percent incline forces eccentric loading of the quads in a different range of motion. 5-10 minutes, twice a week.
How to integrate this into a training week
Eccentric work is a supplement to your aerobic and threshold sessions, not a replacement. A reasonable week for a mountaineer in the build phase:
- Mon · easy zone 2 + reverse step-downs (3 sets)
- Tue · threshold intervals
- Wed · rest or short walk
- Thu · long zone 2 hike with vertical (concentric load)
- Fri · easy zone 2 + slow tempo squats
- Sat · long mountain day, with deliberate downhill segments
- Sun · full rest
Notice that the eccentric blocks are small and never stacked into back-to-back days. The point is consistency and progressive overload, not heroic single sessions.
Recovery from eccentric load
If you have never done dedicated eccentric work, your first week will hurt. The DOMS hits 24-48 hours later and lingers. This is normal - the muscle is rebuilding stronger. By week three, the same load produces dramatically less soreness because your tissues have adapted.
Two practical points:
- Do not panic-dose. Resist the urge to "test" your descent fitness with a full day on the mountain in week one. Build gradually.
- Hydration and protein matter more than usual. Eccentric repair is protein-intensive. 1.6-2.0 g protein per kg bodyweight on training days is well-supported by the literature.
The takeaway
A mountaineer who trains the descent arrives at the summit prepared and at the trailhead intact. The exercises take 10-15 minutes, twice a week. The progression is straightforward. The only thing that has to change is the assumption that the climb is the hard part. For TTM members, eccentric blocks are programmed automatically into the build phase - see alpine training or mountaineering training plan for how that gets sequenced against your specific objective.