In sports, we monitor speed, volume, and heart rate, but often overlook the most trainable asset.

our muscles

Muscle Oxygen data can make you a better athlete

Train.Red Features

We translate our data into comprehensive features to help you guide your trainings

Muscle States

Our smart and adaptive algorithm determines whether your muscle is recovering, working at a light, moderate or hard intensity. It also tells you when your muscles' load is rising.

Smart Rest

Rest is important for your training. But how do you know your muscle is ready? Use Train.Red sensors to track your personal recovery during workouts.

Muscle Stress Score

Muscle Stress Score (MSS) is a quantification of the aerobic stress that is put on the muscle from your training. MSS ic calculated using your hemoglobin data, muscle states and duration.


Controlling the supply and demand of oxygen is essential for pacing your activity

Muscle States


Our intelligent algorithm analyzes relative concentration changes and absolute oxygen percentages to assess your muscle state. It categorizes your muscle's activity into four levels: recovery, light intensity, sustainable moderate effort with anaerobic energy use, and increasing load.

M. State 1

Muscle State 1

1. Recovering State: Recovery depends on exercise factors, not just muscle oxygen needs. This affects 'Recovering state' & 'Smart Rest' recommendations.

M. State 2

Muscle State 2

2. Easy State: this is when your workout feels easy. State 2 activities should feel sustainable for a while. training in this state improves your muscles' oxygen efficiency, boosting muscular endurance.

M. State 3

Muscle State 3

3. Medi State: This is the time spent at a moderate but sustainable intensity during your training.

M. State 4

Muscle State 4

4. Hard State: This is when you mostly use fast energy systems in your workout. It's intense and can't be sustained for long.

M. State 5

Muscle State 5

5. Load State: This is when the resistance increases in your workout, often in strength training or during quick movements. As muscles contract and grow, they press against capillaries within the tissue, briefly blocking blood flow and causing muscle desaturation.


Pacing and Training zones

We know how to do an incremental test with the sensors, but you can use this exact same information during your workouts, in real time.

A traditional training program prescribes output metrics or heart rate, but you can actually be more accurate with our physiological data.

Instead of 3x12 squats with 80kg or 3x20 mins at threshold power use your muscles to guide this load.

Guide Performance

Guide your performance

By using muscle states in real-time, we can assess the demand for oxygen, ensuring muscles can sustain the tempo throughout training or competition. The Muscle States allow athletes to adjust their pace dynamically, enhancing training efficiency. Athletes can push boundaries while minimizing the risk of fatigue or injury and, optimizing performance.

Analyze Performance

Analyze Performance

1. Test yourself

2. Adapt your training Use muscle states to find your training zones.

3.and test again

Use muscle states to find your training zones.

Smart Rest

Train.Red's 'Smart Rest' feature optimizes your workout breaks, recognizing the importance of interval and strength exercise recovery. By utilizing Train.Red sensors, you can monitor your individual recovery progress during each session.

Rest Periods

If you are an endurance athlete and want to monitor how much time you should rest in between sets or if you are training strength and you are not sure when you should start your next set, we might have the solution for you. By looking at the trend of muscle oxygen saturation in the muscle tissue, you can accurately know when your muscle is ready for the next set. 

Stamina Rest Phase I

In stamina-focused training, characterized
by short rests, lighter weights, and higher reps, muscles benefit from efficient refueling and waste elimination. Our system quickly analyzes muscle
reoxygenation post-set, indicating the effectiveness of your recovery. For instance, during a recent workout, your average stamina rest was 35 seconds.

Hypertrophy Rest Phase II

Training for muscle size (hypertrophy) relies on sugar breakdown for energy, causing a burn in your muscles and promoting growth. Optimal R2 Rest duration is crucial – too short hinders recovery, while too long may clear essential metabolic byproducts. In a recent workout, your average hypertrophy rest was 1 minute and 28 seconds.

Maximum Strength Rest Phase III

Intense workouts heavily engage the phosphagen system, a potent but limited energy source. 'R3 rest' signals when you're ready for maximum strength, considering the time required for system replenishment. If, during a workout, you didn't reach your strength rest, it indicates the need for extended recovery.

Muscle Stress Score (MSS)

Muscle Stress Score (MSS) is a quantification of the aerobic stress that is put on the muscle from your training. MSS is calculated using your hemoglobin data, muscle states and duration.
With MSS you can quantify the load on your muscle!


Supply & Demand refers to the balance between oxygen supply to muscles and the oxygen demand of those muscles during physical activity.


During the warming-up, more oxygen should be supplied to the muscle than being demanded. From the moment the chart starts flowing to the right and the supply and demand of oxygen become even, it means that you probably have reached a plateau and you are ready to perform.


In endurance sports, it's crucial to ensure that oxygen demand does not surpass supply. Firstly, exceeding oxygen supply can lead to the accumulation of metabolic by-products, causing fatigue and reducing performance. Additionally, inadequate oxygen supply can result in hypoxia, where tissues don't receive enough oxygen, leading to decreased energy production and impaired muscle function. By maintaining a balance between oxygen demand and supply, athletes can sustain prolonged effort, delay fatigue, and optimize performance in endurance activities.