Usefulness of a Perceived Exertion Scale for Monitoring Exercise Intensity in Adults with Intellectual Disabilities

In order to gain physical fitness and health, exercise must be performed at a sufficient level of intensity. Exercise intensity can be monitored with rated perceived exertion (RPE) scales to promote safe and effective programming. The usefulness of the Children’s OMNI Scale as a subjective measure of intensity for adults with intellectual disabilities (ID) was examined. Heart rate, workload, and RPE were monitored during a progressive walking protocol on a motorized treadmill in 18 adults with ID. Statistical analyses on individual data revealed that significant positive relationships among RPE, heart rate, and workload existed in most participants. However, results were highly variable. Results imply that some individuals with ID are able to provide a subjective estimate of exercise intensity while others may not be able to report accurately. The findings have significant practical implications for exercise programming in this population. Considerable research has indicated that people with intellectual disabilities (ID) have low levels of physical fitness (Graham & Reid, 2000; Fernhall & Pitetti, 2001; Pitetti, Yarmer, & Fernhall, 2001), which likely contribute to the poor health status observed in this segment of the population (Draheim, McCubbin, & Williams, 2002; Janicki et al., 2002; Rimmer, Braddock, & Marks, 1995). Exercise training is critical to increase fitness and to improve overall health in people with ID. In order to be effective, exercise needs to be performed at a minimum frequency, intensity, and duration. Safe and effective exercise prescription is dependent upon accurately monitoring these specific components. While frequency (i.e., bouts per week) and duration (i.e., minutes per bout) are relatively easy to monitor, exercise intensity can be more complicated. There are various methods used to estimate exercise intensity with heart rate monitoring being the most common in the general population. Monitoring exercise intensity may be challenging for individuals with ID due to compromised cognitive functioning. Specifically, heart rate monitoring could be difficult since it involves precision as well as rapid counting. Identifying the exact location (i.e., carotid or radial artery) to palpate requires considerable practice as does applying the appropriate pressure and counting beats. Further, exercising at a safe, age-appropriate target heart rate may be problematic for individuals who have ID since it requires ongoing comparisons to published charts and/or tables. Rated perceived exertion (RPE) scales may be a useful alternative for individuals with ID because they allow a person to simply, and subjectively, express how they feel during exercise. The principle underlying RPE scales is that values selected should have a positive linear correlation with a person’s heart rate (i.e., physical effort) and the exercise workload (i.e., intensity) (American College of Sports Medicine, 2000). Simply stated, as exercise becomes harder an individual’s heart rate increases and they should perceive that added exertion. Accordingly, they should select a numThe authors are very grateful to Catrin Duggan and Michael Martone for their assistance with the data collection. We would also like to thank the CACL Workshop in Antigonish and all of the participants for giving their time and effort to this project. Finally, we appreciate the permission granted by Dr. R. Robertson to reprint the Children’s OMNI Scale of Perceived Exertion. Correspondence concerning this article should be addressed to Heidi Stanish, Department of Exercise and Health Sciences, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA, 021253393. Email: [email protected] Education and Training in Developmental Disabilities, 2007, 42(2), 230–239 © Division on Developmental Disabilities 230 / Education and Training in Developmental Disabilities-June 2007 ber or descriptor on the RPE scale that corresponds to the greater workload. Rated perceived exertion is a reliable indicator of an individual’s exercise tolerance (American College of Sports Medicine, 2000). Since RPE is highly correlated with exercise heart rate and workload, RPE scales are frequently used by practitioners during exercise tests and for exercise prescription. Borg’s RPE Scale is one of the most widely used of the existing scales and was developed as a subjective measure of feelings during exercise that takes into account fitness level, the environment, and fatigue (Borg, 1970; 1998). Rated perceived exertion scales are especially valuable as an indicator of exercise intensity for individuals who have difficulty palpating heart rate or who have limited experience engaging in exercise. The scales have been used with various populations including older adults (Shigematsu, Ueno, Nakagaichi, Nho, & Tanaka, 2004), children (Tenenbaum, Falk, & Bar Or, 2002), and individuals with disabilities (Birk & Mossing, 1988; Holland, Bouffard, & Wagner, 1992; Ward, Bar-Or, Longmuir, & Smith, 1995) as a means of allowing people to express feelings of fatigue and exertion while engaging in physical activity. Two published studies have examined perceived exertion during exercise in adults with ID. Arnhold, Ng, and Pechar (1992) studied the relationship of heart rate, workload, and RPE in 10 adults with ID and a nondisabled comparison group. The authors used the Borg Scale (Borg, 1970) to rate perceived exertion during treadmill walking. Heart rate and RPE were positively correlated (r .65), as were workload and RPE (r .81). The relationships among variables were not significantly different than the nondisabled comparison group. The authors concluded that the ability of adults with ID to accurately perceive physical exertion during submaximal exercise was equivalent to their nondisabled peers. In addition, they reported that the Borg Scale was a useful measurement tool for people with ID. Downing and Keating (2003) examined the effect of verbal encouragement on performance and RPE during a graded exercise test in 16 adults with developmental disabilities. The authors used the Children’s OMNI Scale of Perceived Exertion to gather information. It was found that verbal encouragement led to longer times to exhaustion and greater peak heart rates than no verbal encouragement. However, RPE was not influenced by verbal encouragement during submaximal exercise. Participants without Down syndrome (DS) had longer times to exhaustion but no differences in peak heart rates were found. Since the publication was an abstract and contained only limited details of the study, no information was presented on differences in RPE among genders or people with and without DS. Due to the limited published work, it remains unclear whether or not individuals with ID are able to accurately rate perceived exertion. In order to determine if RPE scales are useful for monitoring exercise intensity in people with ID, more work is required. The importance of examining RPE in this population segment is further supported by evidence that adults with ID generally accumulate a reasonable volume of daily physical activity (specifically walking) but the intensity of the activity is thought to be low and inadequate to achieve health benefits (Stanish & Draheim, in press; Temple & Walkley, 2003). If it is demonstrated that RPE scales are effective for monitoring exercise intensity in adults with ID, then they may be useful for increasing the intensity levels of existing physical activities. The intent of this study is to build upon previous work by further examining the usefulness of the Children’s OMNI Scale of Perceived Exertion as well as examining potential differences between males and females, and individuals with and without DS in regards to RPE. Since differences in maximal heart rate of people with DS have been documented (Fernhall et al., 2001), it seems important to examine individuals with that diagnosis independently. Therefore, the main purpose of this study was to determine the usefulness of the Children’s OMNI Scale of Perceived Exertion for monitoring exercise intensity in adults with ID through examining relationships among heart rate, workload, and RPE during a graded walking test.