CAN PLANTAR FLEXOR STRENGTH PREDICT FALLS IN THE ELDERLY?

Introduction

India is the most populous country having over 104 million elderly persons (aged 60 and above) constituting about 8.6% of the total population in India. The old age dependency ratio increased to 14.9% and 13.6% in males and females respectively in 2011⁽¹⁾. One of the main reasons why this huge number becomes dependent is ‘falls’. Falls are one of the major problems in the elderly and hence are considered as one of the “Geriatric giants”

Every year accidental falls occur in nearly one-third of those aged more than 60 years, with 10% of these falls resulting in serious injury⁽²⁾. Loss of balance and falls in the elderly constitute a major problem associated with human suffering as well as high costs for society⁽³⁾.

But, falls that do not lead to injury often begin a downward spiral of fear that leads to inactivity and decreased strength, agility and balance that often results in loss of independence in normal activities of self-care⁽⁴⁾. With the growing aging population, the number of falls will likely increase in coming years. Therefore, there it is necessary to develop and implement low cost, time-efficient, exercise intervention programs targeting particular muscle groups in order to increase strength, functional mobility and balance in older adults and, subsequently, to decrease the risk of falls⁽⁵⁾.

Hence, finding all the variables influencing the risk of falls in the elderly is essential.

Ageing is associated with reduced muscle strength⁽⁶⁾.  The age-related modifications on motor system can be viewed as examples of an inevitable, genetically programmed process that causes both decline and physiological adaptation in neuromuscular function. These modifications, involving the loss of cells, lead to the reduction in complement of motor neurons and muscle fibres, inducing, in turn, the reduction of muscle mass and strength, especially in the lower limbs⁽⁷⁾.

Amongst the lower limb muscles, the ratio of muscle strength to muscle thickness in the elderly group was significantly lower than that in the young group in plantar flexors (p<0.001), but not in knee extensors⁽⁸⁾.  The strength of ankle plantar flexors (PF) is related to mobility functions of older adults⁽⁹⁾. The ankle PF provides stability for the weight-bearing limb and allows for advancement of the swinging limb in both walking and stair climbing tasks^{(10, 11)}. However, when all 4 muscle groups were considered together, only the PF muscle performance (repeated heel-rise ability) showed a significant association with all 3 mobility tasks. The importance of PF muscle performance in lower extremity ambulation activities has been emphasised^{(9, 10, 11)}. The PF is also a significant predictor of postural control⁽⁹⁾ and balance⁽¹²⁾  in community dwelling older persons.

The mobility requirements for ankle DF during gait and balance are primarily weight-bearing related⁽¹³⁾. There is decrease in ankle joint range of motion with increasing age and this affects balance also⁽¹⁴⁾. Ankle dorsiflexion measured with weight bearing methods resulted in a significant correlations for balance in the older age group⁽¹³⁾

Balance is strongly associated with falls in the elderly. The TUG is a simple and inexpensive tool that was developed to screen functional mobility⁽¹⁵⁾. Within research, the use of the TUG has increased over the last few years, and it is recommended by several geriatric societies when screening for risk of falling.^{(16), (17)}

Thus considering all these factors, this study aims to form a predictive model with these variables (Plantar flexor strength, Dorsiflexion ROM), wherein contribution of each variable to the risk of fall will be identified and thus can be used in the intervention to delay their risk of falls.

Methodology: