Validity and Reliability of Measurements of Elbow Flexion Strength Obtained from Older Adults Using Elastic Bands

Journal of Geriatric Physical Therapy, 2006 by Manor, Brad, Topp, Robert, Page, Phil

Data Analysis

Statistical analyses were performed using SPSS software, version 13.0 (Chicago, III). Following the calculation of descriptive statistics, the validity of elbow flexion strength measurements obtained using elastic bands was explored by calculating Pearson correlations (P

RESULTS

Means � SD for each elbow flexion assessment at time 1, and the elastic band resisted elbow flexion assessment at time 2, are presented in Table 1. Pearson correlations between the measures of elbow flexion indicated that the number of repetitions in the elastic band resisted elbow flexion test at time 1 were moderately correlated with the number of repetitions during the dumbbell weighted elbow flexion test (r = 0.62, P

DISCUSSION

The major findings of the study indicate that the 30-second elbow flexion protocol using elastic bands is a valid and reliable assessment of arm strength among functionally limited older adults. Further, the degree of stability demonstrated by this assessment is similar to that of the dumbbell weighted elbow flexion protocol established by Rikli and Jones.12 These findings are important because resistance training using elastic bands as the means of generating resistance is becoming increasingly popular and is effective among older adults.14-16 The principle of specificity of training indicates that the most sensitive method of assessing strength changes as the result of training is recognized when the method of assessment is as similar as possible to the mode of training. Thus, the most sensitive method of assessing an individual who employs elastic bands as their mode of resistance training is an assessment method that also employs elastic bands.

Finally, an advantage of the elastic band resisted elbow flexion assessment is its versatility and ease of implementation. Elastic bands are inexpensive, light-weight, and may be used in the community as a method documenting improvements in muscular strength as measured by community-based exercise leaders or by older adults themselves.

Several limitations were present in this study. Although correlations between measures were significant, limited variance in one variable was explained by another variable. Specifically, only 21% of the variance in isokinetic elbow flexion torque is explained by the number of arm curl reps using elastic bands. This finding was most likely a result of the inherent characteristics of each assessment. For instance, while movement velocity was controlled in the isokinetic assessment, velocity in the dumbbell and elastic band assessments most likely varied throughout the test, and within each repetition of the test. Also, the 30-second dumbbell and elastic band assessments incorporated an element of muscular endurance that was not tested by the isokinetic assessment. The conclusions of the study were also limited by the nonrandomization of testing. While this may reduce variations in motivation that occur within this population,23 randomization of the tests would have strengthened the study's design. Finally, the study was comprised of a small sample of older individuals who presented with limited functional ability. This particular protocol, therefore, may not be appropriate for higher functioning older adults, and additional research involving this population is needed.