Training Guide – Getting the best out of your Heat Ramp Test

There are two challenges with Heat Training. Firstly, identifying the right temperature to train to (i.e. Heat Training Zone) and secondly, quantifying the results. The Heat Ramp Test, which we have documented here, was established to help solve these challenges and in this article we discuss the Heat Ramp Test and outline how you can use it effectively to help your training. If you are using an indoor threadmill, please follow our heat ramp test for runners.
The Heat Ramp Test is similar to an FTP Test in which athletes test their athletic abilities. In this case it tests thermoregulation and collected data can guide training and provide a picture of the performance level.  

We developed this test out of necessity as there were no practical tests already available for sports people which could be easily used.  
Beginning with trials, we also engaged experienced sports scientists, coaches and athletes to test and critique the Heat Ramp Tests. From the outset we also knew that we would be creating a test protocol which would then naturally be modified by others and can evolve. Currently this test is for indoor cycling and we are also testing an indoor treadmill version.  

A Heat Ramp Test is typically undertaken once, before an athlete starts Heat Training (Heat Adaption / Acclimation). It may then be repeated to compare the results and to document improvements against the first test.  

What is Right Temperature for Heat Training? 

The principle of Heat Training (such as Heat Adaption / Acclimation) is that the body is being conditioned to perform better when it gets hot. When people get hot in sports, the power output drops because the body is diverting blood away from the muscles (for power generation) and to the skin to help cool.

Heat Training creates a physiological trigger that increases plasma and subsequently blood volume. The result is that the blood becomes more efficient at cooling and also can produce more power when hot. This translates into higher power output and endurance for athletes. The science of heat training is described here in more detail.

Many experienced coaches have pinpointed (around) 38.5ºC / 101.3ºF as the ideal Heat Training temperature... when you train too cold then you don't trigger the plasma increase and if you train too hot it is counter-productive as it introduces fatigues, slows recovery and can also be dangerous. Keep in mind, training too hot is a bad idea, so a Heat Training Zone defines a safe and effective core body temperature range for training that it individual to you. 

Despite this background information, humans are not particularly adept at knowing their actual core body temperature. You may feel hot, but your core body temperature can be cool and vice versa - so an accurate thermometer becomes important for Heat Training. 

Measuring core body temperature

Tympanic (ear) and infrared thermometers are not considered medically accurate and the readings can vary significantly which means these are not considered to be a reliable guide. Ingestible e-pills and rectal thermometers in contrast are considered medically accurate and can be used effectively for the Heat Ramp Test and Heat Training. Although these thermometers are also costly and more complex to use. They also need to be able to provide real-time core body temperature readings rather than just single 'spot tests'.  

The CORE Body Temperature Monitor is a convenient option, the readings are considered medically accurate plus it provides real-time metrics. It is no surprise that we highlight the CORE technology, but will stress that e-pills and rectal thermometers are well suited for this type of test. The important consideration is consistency and ensuring that testing methods and conditions remain the same so that the results are repeatable.  

Individual thermoregulation and physiology can differ significantly, for example, some athletes already have natural abilities to perform well in hotter conditions. Reliable core body temperature metrics is important so that each athlete can identify their personal limits and their own Heat Training Zone.  

The Heat Ramp Test helps to identify a Heat Training Zone, as an example this could be between a core body temperature range of 38.4ºC to 38.6ºC / 101.1ºF to 101.5.ºF. Following the test, this range would be the guide for subsequent Heat Training Workouts. 

Successful and failed Heat Ramp Tests 

The good news is that the heat ramp test is easy to perform at home with an indoor training setup. The 'not so good news' is that it is not a pleasant test - it feels hard and is uncomfortable. 

As with all Heat Training, ensure you follow qualified medical advice. We recommend using the services and supervision of an experienced coach. If safety precautions are not followed, there is a risk of heat-stress and athletes and coaches need to be aware that for heat related training, training too hot is not better. 

Setup and Clothing

A Heat Ramp Test and subsequent Heat Training can be performed in a warm environmental chamber, but also at home if this is set up the right way.  

The key is to get warm. Fans should not be used, any ventilation or airflow should be stopped. Even a small draft can help to cool you and extremely cold rooms can also cool you down. 

Dress warm. Wearing winter cycling gear on the indoor trainer slows the natural cooling process and contains the heat. Gloves, a winter jacket, cap and thermal knicks helps to work against the natural cooling to increase the core body temperature sufficiently for the test and training. 

As a guide, for repeated tests which are used to compare results, the testing conditions should be kept identical.

Is my Heat Ramp Test good?  

Usually when your power output, heart rate and core body temperature metrics roughly follow the same curves as our chart, this is successful.  

If your core body temperature flattens during the test and doesn't increase, this is usually because your body is still able to cool, the room is too cool, there may be too much ventilation or you may still be dressed too lightly.  

We recommend proper hydration to make up for the fluids that will be lost. Consider planning your hydration so that in future tests this remains consistent

Keep in mind that the power output should not be held constant. Rather, Heart Rate should be maintained and aim to keep cadence (tempo) constant as well. Your power output should be gradually adjusted accordingly to maintain the constant heart rate. This will lead to the power dropping as the core body temperature increases.

In rare cases, some individuals have lower resting / active temperatures and this can make the test difficult to conduct successfully. Thermoregulation and also individual reactions can vary substantially and you are welcome to contact us for input.

The test may also need to be modified to suit your requirements, while the ramp-up should be gradual, the FTP values can be adjusted and the test conducted again.

When conducting a Heat Ramp Test, if there is any dizziness, nausea or a high-level of discomfort, immediately stop and cool. This test can feel extremely unpleasant and while this is normal, the test should not be conducted or continued if there are any health concerns. 

Ignore your Power

Of course, the end-goal is to improve power output and performance, however during Heat Training exercises, power output becomes a secondary metric. 

Often in training and competition, power output or pace or speed is used as the primary metric. For heat training, athletes should concentrate on the core body temperature and heart rate and adjust power accordingly.  

The Heat Ramp Test begins with a warmup, slowly increasing power and this serves to make the test repeatable. Once the 38ºC 100.4ºF checkpoint is reached, then the heart rate is 'locked' and this heart rate is maintained during the test. 

In a successful Heat Ramp Test, two things will happen. Firstly, the core body temperature continues to rise and secondly, you need to adjust your power output to maintain a steady heart rate. Then, over time, your power output will start to decline as you maintain a steady heart rate while the core body temperature continues to rise.

Finishing the Heat Ramp Test 

There are two ways in which a Heat Ramp Test is completed, the first is when the power output drops to 80% of the original power output value when the test started. The second is when you are exhausted and no longer feel you are able to continue. In both cases you stop pedalling and rest without any extra cooling or warming, just slowly cool down. 
The power output will immediately drop and the heart rate will also start to fall. The core body temperature however may continue to rise for several minutes until your body is able to dissipate the heat.  
At the point in which the test is completed (and you stop pedalling), the core body temperature value is used to help calculate the optimal Heat Training Zone.

Quantify Your Results 

When a Heat Ramp Test is completed and you use calculate your metrics, the result is a Heat Training Zone which is the core body temperature range that can be used a guide for subsequent effective Heat Training. 
Typically a Heat Training Program begins with a dedicated 2 - 4 week dedicated Heat Block Training and is followed by the regular training schedule which incorporates 2 - 4 Heat Training Workouts each week to maintain the conditioning (which will otherwise naturally decline).  

Usually after 3 - 5 days of dedicated Heat Block Training there will be notable physical performance benefits. Athletes often recognise increased power output (or endurance) during their workouts.  

By repeating the Heat Ramp Test and logging the details (and ensuring test conditions are identical), the results can be compared.  

Improved performance can be identified easily if the Heat Ramp Test duration for a subsequent test is longer (for example extending from 35 to 40 minutes). In other words, the body has been conditioned and can maintain a higher power output for longer when it gets hot hot and this translates into a performance benefit.

Customising Heat Tests 

It is intended that coaches and athletes will adapt the Heat Ramp Test to suit their requirements. Consistency in the test protocol is important as well as documenting any changes to the tests. As an example, room temperature, power output and duration can impact the results. By changing the conditions, such as environmental temperature, athletes and coaches can also test the impact of changes when preparing for races.  

Modified Heat Ramp Tests can also serve the purpose of testing the impact of cooling approaches, for example hydration. For customised heat tests, overdressing may not be required. 

Please share your own Testing Protocols, results and experience as this is a rapidly advancing field that benefits from knowledge transfer.