In modern society with an increasing aging population, recent literature has defined sarcopenia as a significant reduced mass and function of skeletal muscle with physical limitations due to aging. Clinically and experimentally, the foot often plays a crucial role in sensorimotor control and movement performance in standing, walking, and running. Apparently, previous literature has shown that the intrinsic and extrinsic foot muscles have significantly reduced muscle morphology and muscle strength in the elderly compared to that of young healthy controls. How to effectively increase foot muscles using muscle-strengthening exercises will be a crucial issue for further research and clinical intervention in this population.

The intrinsic foot muscles (IFM) are the primary local stabilizer to provide static and dynamic stability in the foot, which are part of the active and neural subsystems to constitute the foot core system. The intrinsic foot muscles (IFMs) may play a key role in supporting foot arches (e.g., the medial longitudinal arch, MLA), providing flexibility, stability, shock absorption to the foot, and partially controlling foot pronation. Due to the difficulties in teaching and learning the plantar intrinsic foot muscle (IFM) exercise, the accuracy and follow-up after learning this exercise could be questioned following this exercise program. Physiologically, the effects of integrated exercise intervention may be achieved following more than 4-week intensive exercise intervention at least. How to learn and activate this kind of exercise efficiently and effectively is a key issue for employing these exercise interventions in the elderly with and without sarcopenia.

In this project, we will aim to employ the novel intrinsic foot muscle strengthening device using 3-D printing techniques and to examine the feasibility and reliability of the morphology in intrinsic and extrinsic foot muscles and foot posture before and after exercise intervention using sonographic imaging and foot posture index in the elderly with and without sarcopenia; second, we will investigate whether the immediate and persistent increase in balance control and level-walking after this therapeutic exercise with novel 3-D printing foot core exerciser.

In modern society with an increasing aging population, Asian Working Groups for Sarcopenia (AWSG) has defined sarcopenia as a significantly reduced mass and function of skeletal muscle with physical limitations due to aging. The prevalence in the globe has reported 5% - 25.7% of the elderly population and its associations are very high between daily activity limitations, physical limitations, and premature death. Clinically and experimentally, the foot often plays a crucial role in sensorimotor control and movement performance in standing, walking, and running. Apparently, previous literature has shown that the intrinsic and extrinsic foot muscles have significantly reduced muscle morphology and muscle strength in the elderly compared to that of young healthy controls. How to effectively increase foot muscles using muscle-strengthening exercises will be a crucial issue for further research and clinical intervention in this population.

Anatomically, the intrinsic foot muscles (IFM) are the primary local stabilizer to provide static and dynamic stability in the foot, which are part of the active and neural subsystems to constitute the foot core system. The intrinsic foot muscles (IFMs) may play a key role in supporting foot arches (e.g. the medial longitudinal arch, MLA), providing flexibility, stability, shock absorption to the foot, and partially controlling foot pronation. Due to the difficulties in teaching and learning the plantar intrinsic foot muscle (IFM) exercise, the accuracy and follow-up after learning this exercise could be questioned following this exercise program; Physiologically, the effects of integrated exercise intervention may be achieved following more than 4-week intensive exercise intervention at least. How to learn and activate this kind of exercise efficiently and effectively is a key issue for employing these exercise interventions in the elderly with and without sarcopenia.

This project consists of two main parts - first, we will aim to employ the novel intrinsic foot muscle strengthening device using 3-D printing techniques and to examine the feasibility and reliability of the morphology in intrinsic and extrinsic foot muscles and foot posture before and after exercise intervention using sonographic imaging and foot posture index in the elderly with and without sarcopenia; second, we will investigate whether the immediate and persistent increase in balance control and level-walking after this therapeutic exercise with novel 3-D printing foot core exerciser. More importantly, we elucidate important clinical evidence-based information of long-term novel therapeutic exercise intervention for clinicians and health policymakers.

Inclusion Criteria:

• the elderly with sarcopenia [1, 2] Age is more than 65 years with a medical diagnosis of sarcopenia Be able to independently stand and walk To meet the criteria of the definition of sarcopenia in the AWGS 2019 consensus update on sarcopenia diagnosis and treatment Be able to understand independently the participation consent in this research project
• Healthy elder individuals A neutral foot alignment: determined by measurement of the resting calcaneal stance position (RCSP: between 2˚of inversion and 2˚of eversion) and scores on the navicular drop (ND: between 5 and 9 mm) test.

Foot Posture Index (FPI) Score is between 0 and 5. No pain in the lower limbs No history of lower limb injury that has affected function or caused the individual to seek previous medical or therapeutic intervention within 6 months

Exclusion Criteria:

• All groups not be able to sign the consent form for the participation Traumatic injury to lower limbs which impacted joint integrity and function (i.e., fractures) resulting in at least 1 interrupted day of desired physical activity Major neurological, cardiorespiratory, or circulatory disorders contribute to not being able to independently stand and walk.

Recent intervention/management within the last 6 months

The studies will involve individuals between 65-95 years of age with planned male to female ratio of 1:1