Functional Changes and Power Training in Older Women.

Resistance training has gained popularity in aging interventions since it is effective in countering the loss of muscle mass and strength with senescence. Traditionally, strength training (ST) protocols for the elderly have involved relatively heavy loads (70-80% of maximum force) with the focus being on increasing strength. There is some evidence of increased function after strength training albeit with inconsistent reports in the literature. More recently, several studies have designed resistance training programs that aim to increase power rather than strength, since findings indicate that measures of power are better predictors of physical function than measures of strength. In other words, improving power may be more beneficial to the elderly who are susceptible to functional limitations, mobility disability, and dependency. Since it is difficult to produce a great deal of power with increasing intensities, and lifting heavy loads may not be relevant to everyday functioning in the elderly, studies have investigated training for improvements in power rather than the traditional improvements in strength.

The effects of power training (PT) versus ST on functional outcomes in older adults have varied, with some studies showing enhanced improvements in function, and others showing no difference in function compared to regular ST or compared to other interventions such as walking. Discrepancies might be the result of the variety of functional tests used, mode of training, variable frequency of sessions per week, differences in study length, and adults of varying functional status. It has been suggested that perhaps the standard 3-sessions-per-week frequency may not be optimal for the elderly. A previous investigation demonstrated that the effects from PT at 40% of the 1-repetition maximum (1RM: the highest amount that can be lifted once) in older adults was comparable to the effects from ST at 80% 1RM with improvements being similar between the two modes despite the lower daily ratings of perceived exertion (RPE) reported with PT (PT: RPE for leg press (12.2) and knee extension (14.6) vs ST: RPE for leg press (15.1) and knee extension (17)). Therefore, an 'easier' exercise training experience did not result in sacrifices in gains of strength and power. In theory, these factors (lighter loads, lower perceived exertions, similar strength and power gains) could affect adherence to exercise during and after a research-related exercise intervention has been completed and thus are important considerations in the design of a training program.

The purpose of this research is to investigate the effects of low-intensity (40% 1RM) PT on functional outcomes in older women.

Inclusion criteria

• females, 65 years of age
• agree to the study protocol
• give informed-consent to the proposed research study

Exclusion criteria

• existing acute illness/disease (last six months)
• diagnosed with myopathies
• currently prescribed cardiovascular medications or drugs that may affect muscle mass and/or their response to exercise (thyroid medications, sedatives, beta blockers, some statins)
• are diabetic
• have uncontrolled hypertension
• have been advised against participating in exercise by their doctor