Figure 5. Dynamic monitoring of stress response using the GS⁴.

(A) Conceptual illustration of stress response monitoring by tracking of a subject’s cortisol level with data wirelessly transmitted to a cell phone via Bluetooth. Physical exercise is utilized as a stressor.

(B) Cortisol monitoring from three physically untrained subjects (B1-B3) and one trained subject (B4) in a constant load cycling exercise.

(C) Cortisol levels in serum sampled and analyzed before and after the cycling exercise for four subjects.

(D) Illustration of stress response in relation to the timeframe of cold pressor test (CPT) performed. (E) Cortisol monitoring from four subjects (C1-C4) undergoing CPT. Dynamic cortisol response was evaluated with iontophoresis sweat from forearm sampled and analyzed at 10-minute intervals.

(F) Cortisol levels in serum sampled before, 8 minutes after, and at the end of the CPT experiment.