Non-invasive Monitoring of Glycogen in Real-Time Using an Electromagnetic Sensor

This work presents a novel non-invasive electromagnetic sensor operating at microwave frequencies for real-time monitoring of glycogen in-vitro, developed for forthcoming human trails. Skeletal muscle glycogen stores are a key indicator of athletic performance in activities requiring high levels of energy supply. However, glycogen stores are limited, and depletion can lead to fatigue and reductions in exercise intensity. Thus, athletes need to ensure optimal glycogen synthesis through adapted carbohydrate intake. Real-time monitoring of glycogen stores would allow the optimisation of nutritional strategies (mainly CHO intake) to maintain energy supply and high performance. However, invasive muscle biopsies remain the gold standard method of analysis, only providing a snapshot in time. Glycogen from oyster mixed into a water solution was used to manipulate concentrations observed in healthy humans ranging from 0–400 mmol/L. The electromagnetic sensor used in this study swept frequencies between 10 MHz and 4 GHz, an ideal range to locate any possible frequencies that match glycogens electromagnetic footprint. Data produced from the scattering parameter S₁₁ identified a strong linear correlation between glycogen (mmol/L) and S₁₁ (dBm), r = 0.9, p = ≤0.002, with a R² = 0.87 at 2.11 GHz. This book chapter reports the first significant data that an electromagnetic sensor can successfully monitor change in glycogen concentration. This provides an encouraging basis for future work, as practical non-invasive method for in vivo monitoring of glycogen in human skeletal muscle. The progression of this research will be to analyse the sensor during different glycogen depleting exercise trials in human subjects.