What altitude training athletes need to track
Altitude training is a physiological stressor unlike any other in endurance sport. At elevations above 2,000m (6,500ft), the reduced partial pressure of oxygen triggers a cascade of adaptations - increased red blood cell mass, improved capillary density, and enhanced mitochondrial efficiency - that can boost sea-level performance when done correctly. But altitude is also a performance suppressant in the short term: your VO2max drops, your pace at the same heart rate slows, your sleep quality deteriorates, and your recovery slows. The difference between a successful altitude camp and a wasted one is how well you manage these competing signals.
Baseline gives altitude athletes a dashboard that tracks every relevant biomarker across your devices - Garmin, Coros, WHOOP, Oura, Apple Watch - and correlates them with your training output. The key metrics at altitude are your overnight HRV and resting heart rate (which rise as you acclimatise), your peripheral oxygen saturation (SpO2) if your device supports it, your pacing relative to sea-level benchmarks, your heart rate drift during workouts, and your sleep and recovery trends. These numbers tell you whether your body is adapting to the altitude or breaking down under the combined stress of altitude plus training load.
Goal-specific KPIs Baseline surfaces
HRV and resting heart rate at altitude. At altitude, your resting heart rate typically rises 5-15 bpm and your HRV drops in the first 3-7 days as your body acclimatises. Baseline surfaces your overnight HRV and resting HR from WHOOP, Oura, Garmin, or Apple Watch. As acclimatisation progresses, HRV should trend upward and resting HR should trend back toward sea-level baseline. If HRV continues dropping after day 10, you may be overtraining at altitude - a dangerous combination.
Peripheral oxygen saturation (SpO2). Some watches and rings measure SpO2 during sleep. At altitude, SpO2 drops from the sea-level normal of 95-99% to 88-93% at 2,500-3,000m. Baseline tracks your SpO2 trend over your altitude stay. A rising SpO2 trend indicates successful acclimatisation; a flat or declining trend suggests you may need to descend or reduce training intensity. Combined with HRV, SpO2 is one of the most specific altitude-adaptation signals available.
Pace adjustment at altitude. Your sea-level pace benchmarks don't apply at altitude. Baseline tracks the pace differential - how much slower you run or ride at the same heart rate compared to your sea-level performances. For most athletes, pace degrades 3-5% per 1,000m above 1,500m. Baseline automatically surfaces this delta so you can set realistic training targets at altitude and see when your sea-level pace starts returning (a key sign of effective acclimatisation).
Heart rate drift during training. At altitude, heart rate is elevated at any given pace. Baseline tracks your heart rate decoupling (drift) during workouts and compares it to your sea-level baseline. A higher decoupling rate at altitude is normal, but if it's extreme (above 10% in the first hour), you're working too hard for the elevation and your body may not be adapting well.
Training load with altitude factor. Training Stress Scores calculated at sea level don't account for altitude-induced heart rate elevation. Baseline surfaces your training load (CTL/ATL/TSB) alongside your altitude data so you can see whether the same training volume is producing more physiological stress at elevation. This prevents the common mistake of maintaining sea-level training volume at altitude, which leads to overtraining.
Sleep quality at altitude. Altitude disrupts sleep architecture, particularly slow-wave and REM sleep, due to periodic breathing and reduced oxygen saturation. Baseline connects your sleep data from WHOOP, Oura, or Apple Watch with your training load and HRV. If your sleep quality drops below 75% for multiple consecutive nights while training volume is maintained, consider reducing intensity or descending to a lower elevation for sleep.
Sea-level rebound tracking. The most useful altitude metric for endurance athletes is how performance changes upon returning to sea level. Baseline tracks your key performance indicators - critical pace, FTP, heart rate at given pace, HRV - for 4 weeks before and 4 weeks after your altitude camp. The rebound period typically peaks 14-28 days after descent. Baseline shows the full curve so you can time your race for the peak.
Recommended pricing tier for this goal
Altitude athletes typically carry multiple devices: a GPS watch (Garmin Fenix or Coros) for altitude-adjusted training, a recovery wearable (WHOOP or Oura) for HRV and SpO2, and sometimes a pulse oximeter. The best plan is Baseline Pro at $12/month or $249 lifetime, which unlocks unlimited integrations, AI-powered insights that surface altitude-adaptation trends, the full-resolution heatmap for comparing training across locations, geographic stats to track performance by elevation band, and the achievement system. For the cost of a single night at a high-altitude training centre, you get a full season of data integration and analysis.