Supervisors’ positional power over providers usually implies a special responsibility for promoting effective supervisory relationships.15,19 Inasmuch as the mentioned forms of power do not take account of needs and opinions of providers, they may be described as restrictive,21 which implies a somewhat controlled form of work motivation.9 To the extent they are in accordance with knowledge, interests and needs of the provider, they may be described as promotive,21 indicating rather a self-determined behaviour under autonomous motivation.9