The aim of the present study will be to assess the effectiveness of the multicomponent exercise training in frail for the physical function, frailty and performance.

All the individuals will be assessed two times.

This will be a experimental, randomized controlled intervention study in frail. Subjects will be recruited at the Albertia Care Center, Madrid. The exercise training group will developed a concurrent training 3 days per week during 6 weeks. The control group will follow an usual care also for 6 weeks.

The main variables will be as follows:

• Ultrasound imaging measurements for the lower limb: core muscles, vastus medialis, rectus femoris, vastus intermedius, gastrocnemius, soleus. We will employed a General Electric (GE) Ultrasound device in B mode to assess the thickness of the muscles.
• Heart rate variability with a Suunto smart bell.
• Activities of daily living with the Bartel index.
• Force-velocity profile and muscle power.
• Frailty with the Linda´s frailty criteria.

The exercise program was applied for 6 weeks. A total of 18 sessions were distributed in 3 weekly sessions. The participants performed a resistance exercises: leg press at an intensity of 40%-60% with 10 repetitions, 12 repetitions of steps with their bodyweight and a plantar flexion followed by a cardiovascular high intensity interval training (HIIT) exercise walking on a treadmill.

One measurements will be taken (pre), the second (post) measurements will be performed at 6 weeks.

Inclusion Criteria:

• Men and women aged 75 years or more,
• 2 or more points in the Short Physical Performance Battery (SPPB)
• Capability of walking (alone or assisted)

Exclusion Criteria:

• Severity cognitive alterations
• Severe disability on the Barthel score
• Surgeries in the previous 6 months
• Other any disorder that exclude for the exercise group.