Multicomponent exercise group (intervention): The intervention will consist of a multicomponent exercise training programme24, which will be composed of supervised progressive resistance exercise training, balance-training and walking for 4 consecutive days. During the training period, patients will be trained in 20 min sessions twice a day (morning and evening).

The supervised multicomponent exercise training programme will be comprised of upper and lower body strengthening exercises, tailored to the individual's functional capacity, using weight machines and aiming for 2-3 sets of 8-10 repetitions at an intensity of 40-60 % of 1RMcombined with balance and gait retraining exercises that progressed in difficulty and functional exercises, such as rises from a chair. The second part of the session will consist of functional exercises such as knee extension and flexion, hip abduction, balance movements, and daily walking in the hospital.

Usual care

The intervention will consist of a multicomponent exercise training programme24, which will be composed of supervised progressive resistance exercise training, balance-training and walking for 4 consecutive days. During the training period, patients will be trained in 20 min sessions twice a day. The supervised multicomponent exercise training programme will be comprised of upper and lower body strengthening exercises, tailored to the individual's functional capacity, using weight machines and aiming for 2-3 sets of 8-10 repetitions at an intensity of 40-60 % of 1RM combined with balance and gait retraining exercises that progressed in difficulty and functional exercises, such as rises from a chair. The second part of the session will consist of functional exercises such as knee extension and flexion, hip abduction, balance movements, and daily walking in the hospital.

The functional capacity of participants will be evaluated by the Short Physical Performance Battery (SPPB), the total score ranging from 0 (worst) to 12 points (best) which includes balance, gait and rising from a chair test. Standing balance test consists in the ability to maintain the standing position for 10s with three different foot position: parallel, semi-tandem and tandem. Walking speed measure, the time needed to progress for 4 linear meters with patient's usual speed, assigning a different score according to speed. Chair sit-to-stand assesses the ability to stand from a chair 5 consecutive times without using arms. The SPPB test has been shown to be a valid instrument for screening frailty and predicting disability, institutionalization and mortality.

- Changes in the quality of life measured by the Spanish version40 of the questionnaire EuroQol-5 Dimension (EQ-5D)41. It is an instrument measures 5 dimensions health status: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is rated according to the following levels: a) no problems; b) some problems; c) extreme problems. Besides, it contain visual analogy scale to quantify perceived health of 0 (worst health state imaginable) to 100 (best health state imaginable).