Introduction. This sports-science-related article heavily relies on studies that have reported an increase in beta-endorphin (â-EP) concentration in plasma in response to physical activity. It examines the psychological and physiological effects of physical activity and exercise and reports on a research-experiment-based, endorphin-hypotheses-related pilot study aimed at exploring mood-related â-EP effects occurring in physically active male and female individuals aged 45-55 in response to physical load. Material and methods. Six 45 to 55-year-old individuals (3 males and 3 females) rated as exhibiting moderate and high levels of physical activity in sport's laboratory. International Physical Activity Questionnaire (IPAQ) was used to establish physical activity level. For facial expression analysis a short interview was applied, using software “FaceReader 3.0” (FR). As a load test a veloergometer exercise test was used, and Beta-endorphin (â-EP) levels were measured from venous blood. Results. The findings demonstrated an increase in â-EP levels in 50% of the subjects. No positive relation between â-EP increase and happiness has been observed. In four subjects an increase in disgust was observed due to the laboratory conditions. Five minutes after the load test FR data recorded the reduction or disappearance of negative emotions for all research subjects. Conclusions. Further investigation into the relationship of plasma levels of â-EP and the emotional state of the individual involved in physical activities is needed. This necessitates a further insight into how exercise-elevated endorphins (â-EP) affect mood state outside laboratory conditions. Therefore, a further investigation of people involved in physical recreation activities outdoors is envisaged.