Résumé : Developments in the world of work and in organisational models increasingly require workers to undergo frequent changes. How do in-company training systems deal with the risks of weakening for older workers at work and in employment in such a work environment? We mobilise a case study on a call centre carried out in response to a call for proposals from the French Ministry of Labour on the training of senior employees. We analyse the system of formal and informal training by mobilising interviews with actors in the design of training and interviews with senior telesellers. We find that the existing training system makes it difficult for senior employees to learn new call campaigns within the set time. Moreover, the individual strategies of older learners to meet performance targets, maintain employment and preserve their health are not supported by the work organisation. These results highlight the insufficiently enabling dimension of training and work organisation, particularly for older telemarketers. They also point to several forms of weakening among these workers: at work, in relation to the work and in employment. [résumé revue]