Strength, Power, and Function in Senior Populations

While seniors, 65 years or older, are commonly retiring to active, rather than inactive lifestyles, there is ample evidence of disability and loss of function in the elderly group, rather than increasing enrollment in recreational activities.

A 2005 health survey of those 65 and older, for example, reported at least one functional deficit in 40% of the population. The most common limitation, discovered in 61% of women and 56% of men, was an inability to walk unaided 200 yards or farther, without stopping or discomfort. Additionally, 23% of the men and 29% of the women reported falling within the previous 12 months.

Some evidence claims that these deficits are the result of muscular atrophy, while others attempt to relate falling and other balance issues to sensoryi-motor losses. There is substantive evidence, however, that most limitations due to aging are related to a common cause; a reduction in strength and power.

Hruda, et.al., for example, treated their aging subjects to a power training program, and discovered a 60% improvement in concentric muscle power and a 44% improvement in eccentric muscle power (p <.05). In addition, the authors reported a 33%, 66%, and 31% improvement (p <.05) in a 6 meter timed walk, 30-second chair stand, and an 8 ft up and go, respectively.

The elderly have also demonstrated significant gains not only to basic strength training programs, but to high velocity training protocols as well. Henwood and Taaffe, as an example, instructed their subjects to perform explosive movements on strength training machines at 35, 55, and 75% of their one repetition maximums, and showed significant improvements in major functional indicators, including a 6 meter walk, chair rising, and lifting tasks. The authors reported no injuries or incidents related to the training protocol.

In a related study, Mackey and Robinovitch examined biomechanical and neuromuscular variables that govern the ability to recover balance. Groups of young and elderly subjects were given a task in which they were required to recover from a forward leaning posture, once a support tether was removed. The authors reported significant between-group differences, largely stemming from poorer rate of tension development in the older group. Thus, there is an interdependency between balance control and muscular power.

Some Recommendations for working with elderly clients include:

• Discussion of compliance and adherence for the individual
• Beginning the program slowly and progress logically
• Using light weights (10-15RM) initially, but progressing to heavier workloads
• Using lower loads on machines in conjunction with high velocity movements
• Power and balance training are both highly recommended, however, avoiding balance training modalities that discourage use of proper ankle strategies is warranted

References

Henwood TR and Taaffe DR. (2005). Improved physical performance in older adults undertaking a short-term programme of high-velocity resistance training. Gerontology. Mar-Apr;51(2):108-15.

Hruda, K.V., Hicks, A.L., and McCartney, N. (2003). Training for muscle power in older adults: effects on functional abilities. Can J Appl Physiol. 2003 Apr;28(2):178-89.

Mackey DC and Robinovitch SN. (2005). Mechanisms underlying age-related differences in ability to recover balance with the ankle strategy. Gait Posture. 2006 Jan;23(1):59-68.