“…Cortisol data was obtained in 9 studies [41,43,51,61,[63][64][65][66][67]. A total of 4 studies collected blood samples [41,51,61,65] and 5 collected saliva samples [43,63,64,66,67] for measurements of cortisol concentrations. Finally, 3 studies collected other measurements including eye temperature [46,57], core temperature [45], plasma lactate concentrations [65,68], plasma β endorphin [65], adrenocorticotropic hormone (ACTH) concentrations [61,65], and muscle tone [66].…”