The best skiers and splitboarders you see next winter are not the ones who spent June on the couch. They are the ones who quietly put in the work while everyone else was at brunch — building the legs, the wind, and the movement quality that shows up on day one at Loveland.
Summer is not the off-season for skiing. Summer is ski season prep. And if you live in Colorado, you have a five-month window between the last chair and the first storm to build the kind of fitness that lets you ski more days, ski harder, and ski deeper into the season without your legs giving out on the third run of every powder day.
Here is how to actually use that window.
What ski season demands from your body
Before we talk about training, it is worth getting specific about what skiing actually asks of you physically. It is not just leg strength. A hard ski day is:
Sustained eccentric loading — controlling your body weight against gravity, turn after turn, for hours.
Aerobic and anaerobic capacity — long groomer laps are aerobic; steep bumps and off-piste are repeated anaerobic surges.
Rotational core strength — every turn is a controlled rotation.
Reactive stability — being able to catch and correct mid-turn when the snow surprises you.
Endurance under altitude — most Colorado resorts sit at 9,000 to 12,000 feet, which cuts your VO2 max by 15 to 25% on top of whatever fitness you brought.
Training for a ski season is not training for a marathon, and it is not training for a powerlifting meet. It is specifically about developing the mix of capacities that hold up during a hard day at 11,000 feet with cold air, variable snow, and gravity trying to fold you in half every 30 seconds.
The four training pillars
Every summer program I build for a mountain athlete hits four pillars. Skip any one of them and it shows up in the first month of the season.
1. Strength (especially posterior chain)
The dominant movement pattern in skiing is a controlled squat with rotation, absorbing force through your posterior chain — glutes, hamstrings, and spinal erectors. If your only leg training is bodyweight squats and lunges, you are leaving the actual ski-specific muscles undertrained.
Emphasize deadlifts and their variations, kettlebell swings (a StrongFirst staple for good reason), single-leg RDLs, and step-ups from a real height. Two to three strength sessions a week is plenty.
2. Aerobic base
You cannot buy your way out of poor aerobic fitness with willpower. If your resting heart rate is high and your recovery between hard efforts is slow, every ski day gets shorter by hour three. Build a base with two to three sessions a week of moderate-intensity work: bike, run, hike with a pack, or ruck. Zone 2 — the pace where you can still hold a conversation — is where the aerobic gains happen. Not fast, not fun, but non-negotiable.
3. Mobility
Skiing eats hip mobility, thoracic spine rotation, and ankle range of motion. If you spend the summer sitting at a desk and do not intentionally reclaim range, you will show up in November moving like the Tin Man. Ten minutes of daily mobility work — hip openers, thoracic rotations, ankle drills — pays back massively when you are trying to hold a tuck through a variable groomer at 60 mph.
For a good routine you can actually use, our TRX mobility drills page walks through the four areas most Colorado athletes need work on.
4. Balance and proprioception
Ski turns happen faster than your brain can consciously respond. Everything from mid-turn correction to catching an edge and not falling is proprioceptive — your body sensing where it is and adjusting without you thinking. Train it deliberately: single-leg work under fatigue, unstable surfaces (BOSU, TRX), and reactive drills. This is the one pillar most people skip and it is why they crash more.
The four-phase summer plan
Twenty weeks of summer, roughly. Here is how I lay it out for clients training for a Colorado ski season:
Phase 1 — May and June: Base building
Aerobic development is the priority. Two moderate-intensity aerobic sessions a week, one long session on the weekend (a hike, a ride, or a long trail run). Strength work is general — two full-body sessions a week focused on movement quality, not load. Add mobility work daily even if it is just five minutes.
By the end of June, you should be comfortable moving at Zone 2 for 45 to 60 minutes without excessive fatigue.
Phase 2 — July and August: Strength
Aerobic work stays steady but the emphasis shifts to strength. Three strength sessions a week — one heavy lower body, one heavy upper body, one full-body kettlebell session. Loads go up, reps come down. This is when you build the strength reserve you will draw on all winter.
Add one weekly high-intensity session — hill sprints, kettlebell circuits, TRX Rip Trainer rotational work. Short and hard.
Phase 3 — September and October: Sport-specific
Now the work gets ski-specific. Wall sits and hold-work develop the eccentric endurance skiing demands. Plyometric progressions build reactive strength. If you can, get out on skate skis, roller skis, or start hiking with a heavier pack — the movement patterns transfer.
The backcountry training programming we run kicks up in intensity during this phase, especially for splitboarders and ski tourers whose season starts with big approaches, not lift laps.
Phase 4 — November: Taper and tune-up
Two weeks out from your first ski day, back off the volume. Keep intensity but reduce total work by 30 to 40%. Add sport-specific tune-ups — single-leg jumps, quick lateral movement, cold-weather mobility work. You want to show up on day one feeling springy, not smoked.
Common mistakes to avoid
Ignoring aerobic work because it is boring. Aerobic fitness is what lets you ski more days. Skip it and you will be done by lunch on your third day.
Only training legs. Skiing is a full-body sport. Weak upper body means fatigue in your poles, tired shoulders on lift days, and worse recovery between runs.
Doing leg day the day before a ski day. In-season, keep hard leg work at least 48 hours away from skiing.
Training without a plan. Random workouts get random results. Whether you build the plan yourself or work with a coach, have a structured progression.
Skipping mobility. The five minutes you do not want to do is often the one that keeps you off the injury bench in February.
Get help building it
If this sounds like a lot to piece together on your own, that is kind of the point of what I do. I have been building summer-to-winter programs for Colorado mountain athletes for over 15 years — skiers, splitboarders, alpine climbers, and hut trippers. Everything above gets tailored to what you are actually trying to do next season, what your current fitness is, and how much time you have to give it.
You can see what training with me looks like, learn more about my background and approach, or just reach out with a quick note about what you are training for. First session is a fit-check — we will talk about your goals, look at how you move, and see if we are a match before you commit to anything.
The best ski season you have ever had starts in May. Let us build it.
Sean Sewell is an NSCA-certified personal trainer and the founder of Colorado Personal Fitness in Denver. He coaches skiers, splitboarders, and outdoor athletes using TRX, kettlebells, and functional training methods.