What was the primary reason that the researchers chose to investigate this topic? What is their basic research question? using...

What was the primary reason that the researchers chose to investigate this topic? What is their basic research question? using the article "Walk on the Bright Side: Physical Activity and Affect in Major Depressive Disorder" by: Jutta Mata, Renee J. Thompson, Susanne M. Jaeggi, Martin Buschkuehl, John Jonides, and Ian H. Gotlib