Analyzing the work of the muscles directly we can see very quickly, the possible deviations and adjust the training. By analysing indirect parameter such as the heart rate, achieving a given value may not reflect how the muscles react and we can often train too hard or too weakly.

For interval training, strength training, or other training sessions with a short but intense effort heart rate will indicate effort with significant delay or in a small extent.By directly analyzing the oxygenation of the muscles, we can see their work immediately, which allows us to assess whether we are performing exercises with the appropriate load or intensity.

After completing the exercise, the reoxygenation indicator informs about the level of muscle fatigue, which allows us to adjust the length of breaks and the intensity of training. The analysis of such parameters by means of the heart rate is either impossible or burdened with a significant error.

The heart rate value depends on many external factors, such as air temperature, diet, stress, hydration and the quality of sleep. Eliminating these variables at once is practically impossible or very difficult to achieve. Looking directly into the muscles we eliminate all external factors.

The graph shows the effort with increasing load. By analyzing the heart rate, we see that the pulse increases very straightforwardly for the duration of the effort and increasing load, while our muscles are not working in such a linear way, having different thresholds and limits that we can honestly designate only by analyzing them directly.