Maximal and sustained isokinetic lower-limb muscle strength in hospitalized older people

Maximal strength decreases with aging whereas sustained strength is less affected. Strength decline may be worsened by hospitalization. The aim of this study was to estimate the maximal and sustained isokinetic muscle strength of lower limbs in hospitalized elderly subjects. We evaluated 43 hospitalized elderly subjects (86 +/- 5 years), 28 elderly community-dwelling control subjects (75.4 +/- 6.2 years), and 25 young subjects (28.2 +/- 3.7 years). Among hospitalized subjects, 30 underwent isokinetic evaluation at clinical stability (T0) and again 1 month later (T1). Maximal peak torque (MPT) of the plantarflexors was measured at 30 degrees and 60 degrees /s, and knee flexors and extensors at 90 degrees /s. Evolution of the MPT and the endurance coefficient (EC) on 20 repetitions of plantarflexion at 60 degrees /s were calculated. MPT of plantarflexors and knee flexors and extensors had improved at T1 compared with T0, in hospitalized subjects. MPT evolution and EC values during the sustained strength test revealed no decrease in strength over time in hospitalized subjects at T0 and at T1 compared with community-dwelling control subjects and young subjects. In hospitalized subjects, the absence of an initial phase of fast decrease in muscle strength, which is observed in young subjects during the sustained strength test, could explain this result. It could be related to the modifications of muscle-fiber composition described in elderly subjects and enhanced by hospitalization.