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Trainen met Core: Eenvoudige warmtetraining voor triatleten.

Training with Core: Simple heat training for triathletes.

, by Ronald , 4 min reading time

Once you've passed a heat ramp test and identified your ideal temperature zones, you're ready to start heat training.

Once you've passed a heat ramp test and identified your ideal temperature zones, you're ready to start heat training.


Heat training is a simple technique proven to increase VO2max, lactate threshold power and time trial performance by 5-8% in both hot and cold conditions.

The physiological changes usually involve the creation of more blood plasma and red blood cells, allowing more oxygen to be delivered to the muscles. The benefits of season-long heat training allow you to train at a higher intensity, further improving your racing performance.


The basics consist of 2-3 heat sessions per week, with each session being in your heat training zone for 45-75 minutes. The duration accumulated in the heat training zone is known as thermal load and can be easily tracked in the CORE mobile app.

Building this thermal load is easy with a typical triathlete's training plan. The required thermal load must be achieved weekly; missing 2-3 weeks of heat training will significantly reduce the extra blood plasma you have produced.

While some people choose to do a heat training block (2-4 weeks of 6 days/week of heat training) to increase their plasma gains immediately, most find it more helpful to build those gains more gradually using a schedule like the one below.

Kristian Blummenfelt about training and 24/7 monitoring with CORE

If you do opt for a heat training block, the schedule below can be used for seasonal maintenance.


Wednesday, easy run

Most athletes find it easy to raise their core temperature into the warm training zone while running, even during light exertion. Simply wearing an extra layer or two, even during winter weather, should be enough. If your run isn't long enough to give you 45-75 minutes in the heat training zone, you can sit in a warm bath or sauna after your run to extend your heat session and give you the total thermal load you desire.

Friday, easy bike (optional)

As an alternative to (or in addition to) the gentle run, you can also build up thermal load on the indoor trainer during a gentle session. An extra layer of clothing or turning off a fan is probably all that is needed. Reaching the heat training zone on the bike during an easy outdoor ride can require a lot of extra clothing depending on the air temperature.

Saturday, long drive

Even if your long ride lasts 2-6 hours in total, make sure you don't stay in the heat training zone for more than 75 minutes. More than that can cause excessive fatigue. This means you'll need to add and remove layers during the ride to regulate your core temperature. Arm/leg warmers, a hat and a light jacket may be enough to get you into the warm training zone in mild weather. Colder outdoor temperatures require more layers and more planning.

Note: If you do a transition run after the ride, you may find it challenging if you end the ride with your core temperature in the heat training zone.

Sunday, long run

As with the long run, you should not stay in the heat training zone for more than 75 minutes, even if your total running time is longer. Adding or taking away layers can help keep your core temperature at the desired level. Depending on the air temperature/humidity, it may be difficult to lower your core temperature once you are in the heat training zone.


The CORE mobile app makes it easy to track your thermal load. You can see how many heat training sessions you've done in a week or month, as well as the cumulative time you've accumulated in that zone.

Tip: The CORE mobile app data can also easily be shared with a coach - it will be synced to the coach's app as soon as the athlete uploads it to the CORE app (or if you are using a Garmin device, as soon as the workout syncs with the Garmin app).




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Training with Core: Simple heat training for triathletes.