Why did this experiment not work?

This experiment used all women who lived in high-stressed communities but have no prescribed medications. They were to complete seven days of physical activity and complete a questionnaire that followed. However, the test came back that the physical activity led to still high depression symptoms. Poole stated that “All participants were healthy and within the non‐obese range, with normal blood pressure, but reported relatively high levels of depressive symptoms.” This conclusion still shows true even when some patients were confirmed to under-acknowledge their physical activity. With the addition of physical activity there was no positive change to their depression symptoms. However, this should not become the defining factor that proves the mental capabilities that physical activity can improve. There are various other benefits that physical activity upholds including the benefits within academic engagement, reduction of sedentary behavior, depression prevention in young adults, positive effect on Autism Spectrum Disorder in children, and many more.

Poole, Lydia, et al. “Associations of Objectively Measured Physical Activity with Daily Mood Ratings and Psychophysiological Stress Responses in Women.” Psychophysiology, vol. 48, no. 8, Aug. 2011, pp. 1165–1172.