Box Altitude athlete profile – Demi Duivenvoorden
Introduce yourself and tell us a little about your background and sport
Hi, I'm Demi, a 29-year-old athlete based in Amsterdam. I've always had a passion for sports, trying my hand at various disciplines, but I never quite excelled at any one sport early on. In 2022, I discovered running and fell in love with it. I’ve since completed four marathons. However, after sustaining an injury, I transitioned into triathlons in early 2024, and I've been obsessed ever since.
I’m currently training for my first full-distance Ironman in Barcelona this October and have set ambitious goals, aiming to eventually become a professional triathlete. I take my training very seriously and am constantly pushing myself to new levels in the sport.
How has your experience been with sleeping/training at altitude?
I’m currently training for my first full-distance Ironman in Barcelona this October and have set ambitious goals, aiming to eventually become a professional triathlete. I take my training very seriously and am constantly pushing myself to new levels in the sport.
How has your experience been with sleeping/training at altitude?
I was really curious about trying altitude training since I'm always open to experimenting with new methods to enhance my performance. The system was surprisingly easy to set up, and I’ve been really impressed with the results so far.
Have you faced any challenges or found areas where sleeping at altitude might not be as beneficial?
Personally, I think it's best to taper off altitude training a week or so before race day to allow the body to fully recover and perform at its peak. But overall, it's been a valuable tool during the build-up phase of training.
How do you think sleeping at altitude has impacted your overall performance and recovery compared to other methods you’ve tried?
I’d say sleeping at altitude has impacted my performance and recovery in a unique way. It doesn’t necessarily compete with other tools I’m using—like the sauna, cold plunge, or compression massage—but it complements them. It has more of a compounding effect, helping me push my limits during training while still supporting recovery.
Where I’ve really seen the difference is in my endurance and ability to sustain higher intensities, especially on the bike. It feels like altitude training adds an extra edge that, combined with my other recovery methods, enhances my overall performance.
I’d also recommend using it consistently over a longer period for the best results, but be mindful of tapering off in the week before a race to allow full recovery. Combine it with other recovery tools like proper nutrition, rest, and active recovery to maximize the benefits.
In terms of recovery, while I still rely heavily on other tools like cold plunges and compression massage, I’ve noticed that altitude sleep helps me adapt to tougher training sessions faster. Overall, it's had a strong impact on both my endurance and overall performance capacity.
What positive changes have you noticed in your performance or recovery since incorporating altitude sleep into your routine?
One of the biggest changes I’ve noticed is my ability to sustain higher intensities for longer periods, especially on the bike. On top of that, my heart rate has dropped, which is a great sign that my body is adapting well. Overall, the benefits have been noticeable, and it’s definitely had a positive impact on my training.Have you faced any challenges or found areas where sleeping at altitude might not be as beneficial?
While I've seen a lot of benefits from sleeping at altitude, there are definitely some considerations when it comes to timing. I’ve noticed that it might not be ideal to use in the final week leading up to a big race. During that time, recovery and rest are key, and sleeping at altitude can add an extra level of stress to the body that could interfere with full recovery.
Personally, I think it's best to taper off altitude training a week or so before race day to allow the body to fully recover and perform at its peak. But overall, it's been a valuable tool during the build-up phase of training.
How do you think sleeping at altitude has impacted your overall performance and recovery compared to other methods you’ve tried?
I’d say sleeping at altitude has impacted my performance and recovery in a unique way. It doesn’t necessarily compete with other tools I’m using—like the sauna, cold plunge, or compression massage—but it complements them. It has more of a compounding effect, helping me push my limits during training while still supporting recovery.
Where I’ve really seen the difference is in my endurance and ability to sustain higher intensities, especially on the bike. It feels like altitude training adds an extra edge that, combined with my other recovery methods, enhances my overall performance.
Would you recommend sleeping at altitude to others in your sport, and if so, why?
If you're participating in Ironman events with the goal of just finishing and having a great experience, sleeping at altitude might not be necessary. However, if you’re serious about the sport and truly focused on performance—if you're looking to push your limits and see what your body is capable of—then I highly recommend it. It’s an excellent tool for athletes who want to take their training and endurance to the next level and are committed to seeing real improvements in their performance.
If you're participating in Ironman events with the goal of just finishing and having a great experience, sleeping at altitude might not be necessary. However, if you’re serious about the sport and truly focused on performance—if you're looking to push your limits and see what your body is capable of—then I highly recommend it. It’s an excellent tool for athletes who want to take their training and endurance to the next level and are committed to seeing real improvements in their performance.
What advice would you give to athletes considering incorporating altitude sleep into their training routine?
My advice to athletes considering altitude sleep is to first assess where they are in their training and goals. If you’re looking to optimize your performance and willing to experiment with new methods, altitude sleep can be a great addition. However, it’s important to start gradually and listen to your body, especially at higher simulated altitudes, as it can be an added stressor.I’d also recommend using it consistently over a longer period for the best results, but be mindful of tapering off in the week before a race to allow full recovery. Combine it with other recovery tools like proper nutrition, rest, and active recovery to maximize the benefits.
In what specific areas (e.g., endurance, strength, recovery) have you seen the most noticeable improvements from sleeping/training at altitude?
The most noticeable improvements I’ve experienced from sleeping and training at altitude have been in my endurance and cardiovascular efficiency. I’ve found that I can sustain higher intensities for longer, especially during cycling sessions, without feeling as fatigued. My heart rate has also dropped, which indicates better aerobic conditioning.In terms of recovery, while I still rely heavily on other tools like cold plunges and compression massage, I’ve noticed that altitude sleep helps me adapt to tougher training sessions faster. Overall, it's had a strong impact on both my endurance and overall performance capacity.
Have you noticed any changes in your sleep patterns or quality since you began sleeping at altitude?
Since I began sleeping at altitude, I haven’t noticed any significant changes in my sleep patterns, but there have been occasional nights where I feel a bit more restless, especially at higher simulated altitudes. In fact, during the first week, my WHOOP sleep scores dropped a bit. That said, once my body adapted, the overall quality of my sleep improved, and I still wake up feeling rested.How has sleeping/training at altitude influenced your day-to-day recovery or overall well-being?
Sleeping at altitude has noticeably improved my recovery. I feel like my body is adapting better to the demands of my training, allowing me to recover more effectively between sessions. This has led to less fatigue in my day-to-day life and an overall boost in energy levels.