Assessment of Fall Risks and Subject-specific Training for Fall Reduction

Forty older adults (study group) with high risk of fall (i.e. with one or more fall in the past 12 months) will be recruited. The fall mechanisms will be examined in previous Aims 1 and 2 part of this study.

Assessments will be conducted to identify the fall risks and falling mechanisms by measuring subjects' responses to the movements of the footplates the subject stands on. Training procedures will then be designed for each subject, including training both in the research lab (once per week) and at home (three times per week) for six weeks. The subject will also revisit the lab for a follow-up assessment two months after the 6-week training.

Based on the identified falling mechanisms, a specific training for each subject will be set up using the sliding stepping fall rehabilitation system for one session per week over six weeks in the lab. The participants will also do home training exercises 3 times per week after initial in-lab instructed training. Participants will come to the lab and have biomechanical and clinical evaluations before and after the 6-week training (called Pre & Post), and then at a two-month follow-up as the final evaluation for total three times of evaluations.

All the subjects will be informed about the experimental procedures, and sign an IRB approved consent form prior to study participation and experimental tests.

All participants will be protected from the risk of falling with a harness system. The harness is mounted in mobile cart. A researcher will push the mobile cart following the participant's walking while walking on the ground.

Home-based training: The older adults will also undergo corresponding home-based training. Training at home may include normal walking and strength training based on the results in-lab assessments for each older adult and research team instructions.

• . If the participant shows instability during walking in any specific perturbation directions or with excessive body swaying (left-right, forward-backward, or any oblique directions) based on the initial lab assessment, the participant will practice walking with a cellphone strapped on the chest in home training. A cellphone App will detect potential excessive body swaying in any directions and prompt the participant with real time audio-visual feedback to reduce sway in the specific directions. During the walking training at home, the participant will set up for a distance of a few meters to walk and repeat the walking distance for 12 to 15 times in a slow speed. the participant can take short break between the walking trials.

• For protection of falling risk, the participant needs to have a family member to help check the walking ground first before the walking to make sure the ground condition is good and clean.
• If the participant uses a cane or walker regularly, the participant will continue using the cane or walker during training at home with the cellphone attached.
• The participant should be monitored by a family member while doing the training at home.
• Training improvement will be evaluated in the weekly lab session. It is possible to make adjustment of the training program as the participant progresses.
• . If the subject is diagnosed with collapse-related vertical instability associated with falls, lower-limb muscle strengthening will be emphasized in the training. The subject may work out with a Shuttle Mini-Press, AB Squat machine, Rowing machine, or Upright Row-n-Ride at home. The several exercise machines are similar to each other in strengthening the lower limb muscles but the challenging level gradually increasing. The Shuttle Mini Press allows the subject to train in stable seated or in-bed postures. The AB Squat machine allows squatting exercise with the two feet always on the ground. The rower allows seated sliding training. The Upright Row-n-Ride allows training in up-and-down fashion. The research team will select one machine appropriate for the subject to take home. The exercise will be 3-5 sets a day and about 15 repetitions per set. In the beginning, the exercise can be slower and with fewer repetitions based on the subject's capability. The subject can take a short break between the strength training sets. As the subject progresses, the subject may change from one exercise machine to another.

Inclusion criteria

• Age 60 to 85 years old
• Have a family member at home for safety.
• There is no severe injury or pain at the lower extremities.
• With one or more falls in the past 12 months or walk with instability
• Individuals who are taking medication, there should be no planned medication changes for the study duration of 3.5 months.
• All the participants should be capable of independent walking.

Exclusion criteria

• Enrollment in another lower limb rehabilitation program;
• severe pain in the lower limbs;
• previous myocardial infarction
• Body weight over 280 lbs
• Cognitive impairment (Mini-Mental Status Examination (MMSE) score less than 25)