Purpose: The objectives of this study were (1) to examine the effects of a 12-week exercise cessation period separating two 12-week exercise sessions on physical variables in an elderly institutionalized population and (2) to explore overall programme effectiveness. Methods: The functional mobility of 25 elderly institutionalized adults participating in an existing exercise programme was examined using a one-group, interrupted time-series design. Functional mobility was evaluated at four time points during two cycles of a 12-week exercise programme, alternating with a 12-week period of no formal exercise. Results: The primary outcome was the change in functional mobility scores, assessed at baseline, 12, 24 and 36 weeks. In both the higher-functioning (HF) group and the lower-functioning (LF) group, the cessation of exercise was associated with deterioration in physical function. The overall noncontinuous nature of the programming under study also seemed to be detrimental to the physical function of the LF group. Conclusions: Findings of this small-sample study support the need to modify common practices in exercise programming for older, institutionalized people.Key Words: exercise cessation, exercise class, exercise programming, institutionalized elderly, physical function. Ré sultats : Le premier ré sultat observé a é té un changement dans les mesures de la mobilité fonctionnelle au dé but de l'é tude, puis aprè s 12, 24 et 36 semaines. Dans le groupe à haut fonctionnement (HF) comme dans le groupe à faible fonctionnement (FF), l'arrê t des sé ances d'activité physique a é té associé à une dé té rioration de la fonction physique. La nature globale non continue du programme auquel s'est inté ressé e cette é tude a é galement semblé nuire à la fonction physique du groupe FF. Conclusions : Les conclusions de cette é tude ré alisé e sur un petit é chantillon appuient la né cessité de modifier les pratiques usuelles lié es aux programmes d'exercices pour les aîné s en institution.