What Is The Optimal Sampling Frequency For Near-infrared Spectroscopy (NIRS) Measurements To Accurately Capture The Dynamic Changes In Muscle Oxygenation And Deoxygenation During High-intensity Interval Training (HIIT) In Athletes With Varying Levels Of Aerobic Fitness, And How Does This Frequency Impact The Reliability Of Calculating Oxygen Extraction And Utilization Rates?

The optimal sampling frequency for near-infrared spectroscopy (NIRS) during high-intensity interval training (HIIT) in athletes is between 10 Hz and 50 Hz. This range is chosen to balance the need for capturing rapid changes in muscle oxygenation with considerations of data noise and practicality.

For most applications, a sampling frequency of 10 Hz to 30 Hz is typically sufficient and commonly used, as it provides adequate temporal resolution to track dynamic changes without introducing excessive noise. Higher frequencies, such as 20 Hz to 30 Hz, may offer better reliability in calculating oxygen extraction and utilization rates by more accurately capturing the rapid fluctuations in oxygenation levels, especially in fitter athletes who may exhibit quicker responses.

The reliability of these calculations depends on the sampling frequency's ability to accurately capture the rate of change in deoxygenated hemoglobin. Higher frequencies within the recommended range enhance the precision of these calculations, reducing the risk of underestimation or overestimation. Thus, while 10 Hz is a common choice, 20 Hz to 30 Hz is often preferred for its balance of accuracy and practicality.