Use of heart rate reserve and rating of perceived exertion to prescribe exercise intensity in diabetic autonomic neuropathy.
ABSTRACT Individuals with diabetic autonomic neuropathy (DAN) exhibit an increased resting heart rate but depressed maximal heart rate. Thus, the purpose of this study was to examine the validity of using either percent of heart rate reserve (HRR) or a rating of perceived exertion (RPE) scale to prescribe exercise intensity in diabetic individuals both with and without DAN.
The subjects consisted of 23 individuals with type 2 diabetes, ages 45-75 years, with (DAN; n = 13) or without (No DAN; n = 10) clinical signs of DAN, as assessed by heart rate variability using the expiration-to-inspiration ratio of the R-R interval. Peak aerobic capacity was determined using a graded protocol on a cycle ergometer, with RPE, heart rate, and VO(2) values recorded at each stage.
The subjects were similar with the exception of depressed autonomic function in DAN subjects. Peak respiratory exchange ratio values were significantly higher (P < 0.05) in the DAN group (1.08 +/- 0.02 vs. 1.02 +/- 0.01 in No DAN subjects), although DAN subjects exhibited a significantly lower (P < 0.05) peak exercise heart rate. A similarly highly linear relationship between %HRR and percent VO(2) reserve (VO(2)R) existed for both groups (r = 0.98). A similar slightly weaker relationship (r = 0.94) was found between RPE and %VO(2)R.
In conclusion, in diabetic individuals, %HRR provides an accurate prediction of %VO(2)R and can be used to prescribe and monitor exercise intensity, regardless of the presence of DAN. The RPE scale is also a valid, albeit slightly less accurate, method to monitor exercise intensity in diabetic individuals.
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ABSTRACT: To examine whether a subjective measure of moderate-intensity exercise (12-13 on Borg's ratings of perceived exertion scale; RPE) corresponds to the target heart rate for moderate-intensity exercise (40-59% heart rate reserve; %HRR) and to determine the characteristics of those for whom RPE does not appropriately estimate exercise intensity. 3582 individuals with type 2 diabetes (age: 58.3±6.8 years; BMI: 35.9±5.9 kg/m(2)) underwent a maximal exercise test and minute-by-minute HR and RPE were recorded. Linear regression was used to determine the %HRR corresponding to an RPE of 12 and 13 for each individual. At an RPE of 12 or 13, 57% of participants fell within the target 40-59%HRR range, while 37% and 6% fell above and below this range, respectively. Participants with a %HRR ≥60% (above range) were more likely to be female (OR: 1.19; 95% CI: 1.01,1.40), African American (OR: 1.65; 95% CI: 1.35, 2.02) or Hispanic (OR: 1.57; 95% CI: 1.27, 1.95), have a higher BMI (OR: 1.03; 95% CI 1.01, 1.04) and HRmax (OR: 1.02; 95% CI: 1.01, 1.02), and lower fitness (OR: 0.90; 95% CI: 0.85, 0.94) and RPEmax (OR: 0.68; 95% CI: 0.63, 0.73), compared to those within the target 40-59%HRR range (p-values'<0.05). RPE appropriately gauges exercise intensity in approximately half of overweight individuals with type 2 diabetes; however, more than one-third of participants were at an increased risk of exercising at a higher than prescribed intensity when using RPE. Future studies should continue to examine the characteristics of individuals for whom RPE appropriately estimates exercise intensity and for those whom it does not.
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ABSTRACT: Both peripheral and autonomic neuropathies are characterized by a progressive loss of nerve fiber function. Most peripheral neuropathy affects the extremities, particularly the lower legs and the feet, but also the hands, whereas damage to the autonomic nervous system may lead to imbalances between the sympathetic and parasympathetic nerve fibers that innervate the heart and blood vessels, as well as abnormalities in heart rate control and vascular dynamics. To prescribe or engage in exercise that is both safe and effective, health care providers and patients with diabetes mellitus need to increase their understanding of the pathophysiological nature of neuropathies and the physical activity hurdles that may arise from the presence of a neuropathy. With proper care and preventative measures, patients with diabetes mellitus that experience either type of neuropathy can benefit from regular participation in mild to moderate aerobic, resistance, and balance activities, assuming they take any potential alterations into account to ensure that exercise is safe and effective.The Physician and sportsmedicine 02/2014; 42(1):15-23. DOI:10.3810/psm.2014.02.2043 · 1.49 Impact Factor