Alberts's paper in two parts:
http://www.medscape.com/viewarticle/751998
http://www.medscape.com/viewarticle/751998_2
"It Is Not About the Bike, It Is About the Pedaling
Forced Exercise and Parkinson's Disease"
Jay L. Alberts; Susan M. Linder; Amanda L. Penko; Mark J. Lowe1; Micheal Phillips
Exerc Sport Sci Rev. 2011;39(4):177-186.
John