Aerobic exercise is promoted when individual performance affects the group: a test of the Kohler motivation gain effect
Annals of Behavioral Medicine (2012) - Comment
pubmed: 22576339  doi: 10.1007/s12160-012-9367-4  issn: 1532-4796  issn: 0883-6612 

Brandon C. Irwin, Jennifer Scorniaenchi, Norbert L. Kerr, Joey C. Eisenmann, Deborah L. Feltz