When temperatures drop and the roads turn icy, even the most dedicated runners face a tough decision: bundle up and risk slipping or stay inside and risk losing fitness. The truth is, some of the best gains happen during the offseason (and indoors), if you know how to train for them. Cold weather doesn’t have to mean losing your edge. In fact, it can be one of the best opportunities to build new strengths that often get overlooked during the outdoor season. For many athletes, winter becomes a time to step back, focus on weaknesses, and develop the kind of well-rounded fitness that pays off when the weather turns.
Having coached athletes across the full spectrum of competitive fitness, one thing has become clear: the approach to offseason training can look very different from athlete to athlete. Ironman triathletes and ultrarunners who are chasing endurance have very different offseason needs than CrossFit or HYROX competitors. On the surface it feels obvious what each group should focus on, but winter training has a way of reshaping those assumptions. These athletes are all pushed to train indoors for different reasons, but each of their approaches has delivered improved running results across the varied demands of their sports.
Jacinda Rose—an active-duty member of the United States Airforce, multi-time Ironman triathlete, and ultrarunner—has been using intervals and hybrid training methods to increase her capacity and speed for years. Whether overseas on an airbase or living in the rainy Pacific Northwest, her training has necessitated creativity when safety or weather confine her indoors. We’ve discovered “that the consistent work we put in on things like long efforts on the rower, endless burpees, and lots of lower body lifting, prepared my body for more than I could imagine,” says Jacinda. “This training made me strong enough to complete my first 50-plus mile ultra, a 24-hour effort of 81 miles, and take 2.5 hours off my Ironman time!”
Jacinda’s Recommended Workout:
Part 1
3 x 10 box squat (slow down, fast up)
Part 2
5 rounds for time:
25 cal row (100 jump rope if no rower)
25 burpees over rower
25 double dumbbell squats (light bodyweight if no dumbbells)
Endurance athletes often overlook the value of resistance training, but lower body strength is a key part of Jacinda’s success. The box squats at the start of her session build power, reinforce leg drive, and improve the durability she needs for long efforts. In addition to her long aerobic indoor bike and swim sessions, these cyclical HIIT style training blocks help build her speed and peak output. We’ve also noticed significant endurance gains when maintaining elevated heart rates above her threshold for moderate durations, while forcing the body to move through different patterns under steady fatigue.
Hege Nyquist and Sebastian Skadal, top finishers in the HYROX Pro division, are training to meet the demands of sustained intensity, strength under aerobic fatigue, and the ability to complete repeatable efforts that elevate heart rates. “Training indoors has honestly become one of our biggest advantages,” Hege says. “Because we live in Norway, we spend months at a time doing almost all of our running and conditioning inside. Instead of seeing that as a limitation, we’ve learned to use it as a strength.”
“The Erg machines let us control pace, effort, and recovery with almost perfect precision, which is exactly what HYROX demands,” Hege adds. “We do a lot of our conditioning work on the rower, bike, and SkiErg, combined with metcons and treadmill running intervals. Those sessions have taught me how to stay calm under high intensity and settle into race pace without blowing up. When competition comes, that controlled intensity feels familiar because we’ve hit it so many times indoors. The indoor training really carries over directly into both running speed and overall race resilience.”
Hege and Sebastian’s Workout:
Machine interval progression: Set a baseline week 1, then add 1 calorie to each machine every week.
Every minute for 30 minutes.
Minute 1: SkiErg 15/12 calorie M/F
Minute 2: BikeErg 17/13 calorie M/F
Minute 3: RowErg 18/14 calorie M/F
Leave 5-10 seconds for transition between machines.
Hege and Sebastian’s goal is to hit calorie targets with only a few seconds to transition. The shift in movement pattern provides just enough muscular relief, while the lungs and heart continue to pump at near maximal sustainable pace. Adding a single calorie after each successful week creates a simple and measurable progression that not only increases output but builds confidence marked by visual improvement. The machines or movements you have available are less important than maintaining output and progressive overload near your physical limit. A treadmill, burpees, jump rope, or any other cardio option can work within the same structure and will result in faster and more efficient running.
Running has become increasingly common in CrossFit competitions, but it often shows up in unpredictable distances, on odd surfaces, and in conditions that athletes cannot fully prepare for during the season. With a sport that already demands so much variety, it is difficult for a CrossFit athlete to build a true running base mid-season while also balancing strength, gymnastics, and mixed conditioning.
Isabella Barclay, a champion CrossFit athlete from Northern Canada, takes the most direct approach to improve her running in the winter. As she explains, "In Saskatchewan our running season is unusually short, sometimes six months or less, but that does not mean training stops. Some of the biggest CrossFit competitions happen during our heavy winter months, and running has not always been one of my strengths, so we keep working no matter the weather. We found an old treadmill for the garage and it does the job.
“You do not need a perfect track, a big running group, or the best equipment to improve. You just need something you can be consistent with," Isabella adds.
Isbella Barclay’s Workout:
Here’s a 5-week progression to improve 5K pace.
5k protocol 2 days a week (Monday/Thursday):
Mondays: threshold/aerobic floor
Goal: raise lactate turn-point so 5K pace feels easier
4-week progression (run once per week)
Week 1: 5 x 5 min at threshold (current 5K + 3-5 sec per K), 1 min jog at easy pace
Week 2: 4 x 6 min at threshold (current 5K + 5-10 sec per K), 1 min easy
Week 3: 3 x 8 min at threshold (current 5K + 5-15 sec per K), 75 sec easy
Week 4: 20-24 min continuous at threshold (current 5K + 10-20 sec per K)
Week 5: Test
Thursdays: V02 and speed training
4-week progression (day 2, once per week)
Week 1: 6 x 800 m at (goal pace − 3 sec per K) 2 min 30 sec easy jog
Week 2: 8 x 600 m at 3K effort (goal pace − 10 to 15 sec per K), 2 min easy jog
Week 3: 12 x 400 m at 3 K effort (goal pace − 10 to 15 sec per K), 200 m easy jog
Week 4: 5 x 1,000 m (goal pace to P − 3 sec per K) + 200 m easy jog
Week 5: Long recovery jog
Bella’s running work is built around steady progression and repeatable intensity. These intervals teach her to settle into pace, stay relaxed, and improve both her aerobic base and her ability to push toward new personal bests. Threshold sessions raise her capacity to hold strong, controlled efforts, while the VO2 intervals sharpen speed and build confidence at faster paces. The structure and principles of these sessions can be adapted for any distance and allow for consistent progression through the winter, building a foundation that directly improves running when it matters most.
Rather than seeing the cold as a setback, winter can be viewed as a season of opportunity. It’s the perfect time to diversify training and build parts of your fitness that get overlooked during the rest of the year. No matter your running goals, adding crossover work can build endurance and increase speed and longevity for the season ahead.
If you’re a dedicated runner, adding strength and resistance work will build resilience and power. If you’re a hybrid athlete, focusing on aerobic base building and machine output can raise your overall ceiling. Finally, if you want to get into running or improve your speed, a simple treadmill or any indoor space is enough to start building consistency through intervals.
These athletes train across multiple domains. Some emphasize endurance, others strength or mixed conditioning, but every one of them has seen the value of stepping outside their usual routine. Winter gives you the time and space to do the same. It’s a great season to try something new and come into spring stronger and faster than you’ve ever been.
Author Bio: KJ is a competitive fitness coach and owner of Endless Training, where he works with CrossFit, HYROX, and endurance athletes ranging from aspiring qualifiers to champions. He is known for detail-oriented individualized programming and a simple philosophy: progress has no finish line.
Find him and Endless Training at @johnsonkenny and @endlesstrainingco on Instagram.
