Effects of Improved Calf Muscle Function on Gait, Balance and Joint Loading in Older Adults

Improving Plantarflexor Muscle Function to Alleviate Decline in Mobility, Loss of Balance and Detrimental Knee Joint Loading in Older Adults

This study investigates the role of calf muscle function in gait performance, balance and knee joint loading. Previous studies have linked age-related loss of calf muscle function with impairments in gait performance and balance, and increased loading of the areas of the knee joint that are susceptible to the development of osteoarthritis. In this study, an exercise intervention targeting structural and neural aspects of impaired calf muscle function with ageing is utilized. The intervention lasts 8 weeks and includes either biofeedback training using electromyography to alter muscle activation patterns or a combination of biofeedback training and strength training for the calf muscle to modify calf function during walking. The study will test whether the intervention improves walking speed, reduces the metabolic cost of walking, improves standing balance and reduces knee joint loading.

Osteoarthritis, Knee, Achilles tendon, Triceps surae, Balance, Electromyography, Biofeedback, Strength training, Gait, Walking

Thirty older adults will be recruited and randomized into two groups. The other groups receive an intervention including strength training and gait retraining lasting 8 weeks while the other group receives only the gait retraining. Outcome measures are obtained before and after the intervention period.

8-week intervention. Intervention includes weekly gait retraining sessions with real-time electromyography biofeedback.

8-week intervention. Intervention includes weekly gait retraining sessions with real-time electromyography biofeedback and home-based strength training session for plantarflexor muscles three times per week.

Gait retraining using real-time electromyography biofeedback performed once per week for eight weeks. During the gait retraining session the participant is walking on a treadmill while receiving information on calf muscle activation. A single session includes five bouts of walking each lasting for 5 minutes. During the first bout, the participant is receiving feedback (visual and auditive) on soleus muscle activation with the aim to increase it by 20% from their normal walking. During the second bout, the participant is receiving feedback (visual and auditive) on medial gastrocnemius muscle activation with the aim to decrease it by 20% from their normal walking. During the last three bouts, the participant is receiving feedback (visual and auditive) on the soleus to medial gastrocnemius muscle activation ratio with the aim to increase it by 20% from their normal walking. If hitting the target, the aim is increased by 5% for the subsequent bout.

Gait retraining using real-time electromyography biofeedback performed once per week and home-based calf muscle strength training performed three times per week for eight weeks. The gait retraining is identical to the one intervention described for the intervention group "Gait retraining". The strength training is performed three times per week except for the first week in which it is performed two times. The session contained a warm-up (3x10 repetitions of two-legged heel raises) and maximal isometric calf muscle contractions. The maximal contractions are performed using a custom device with the ankle in dorsiflexion and the knee flexed by 100-120 degrees. Three sets of 10 repetitions (3-second contraction and 3-second rest) are performed with both legs and with maximal effort and 1-minute rest between the sets.

Change in tibiofemoral compressive loading during walking estimated using musculoskeletal modeling and simulation. Loading is calculated separately for medial and lateral compartments of the tibiofemoral joint.

Achilles tendon stiffness evaluated using combination of ultrasonography, motion analysis and force measurements.

Time series of lower limb joint angles during walking stride assessed using motion capture system and inverse kinematics.

Time series of lower limb joint moments during walking stride assessed using inverse dynamics based on motion capture system and instrumented treadmill data.

Time series of lower limb joint powers during walking stride assessed using inverse dynamics based on motion capture system and instrumented treadmill data.

Distribution of total positive lower limb work between the joints during walking assessed using inverse dynamics based on motion capture system and instrumented treadmill data.

Soleus and gastrocnemius muscle volume estimated with combination of ultrasound and magnetic resonance imaging.

Inclusion Criteria: age between 65 and 75 Exclusion Criteria: dependent living status not able to walk without an assistive device or for 30 min without stopping diagnosed neurological disease or joint disorder and pain during walking surgery on lower extremities current musculoskeletal injury previous cardiovascular event or symptoms during exercise (acute ECG change, coronary disease, symptomatic arrhythmia, symptomatic coronary stenosis, heart failure, myocarditis, pericarditis, pulmonary embolism, pulmonary infarct, artery bulge or rupture risk) body mass index <18 or >35 kg/m2 contraindications for magnetic resonance imaging Mini Mental State Examination score of 23 points and lower

Data obtained during the study will be shared with other researcher after the results have been published. Details of the data will be updated later.