Fitness Affects the Pressor Response to Dynamic Exercise in Older Adults in
                                     a Mode an...
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Fitness Affects The Pressor Response To Dynamic Exercise In Older Adults In A Mode And Sex Specific Manner


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Fitness Affects The Pressor Response To Dynamic Exercise In Older Adults In A Mode And Sex Specific Manner

  1. 1. Fitness Affects the Pressor Response to Dynamic Exercise in Older Adults in a Mode and Sex-Specific Manner Dustin M. Grinnell, Joaquin U. Gonzales, and David N. Proctor Pennsylvania State University Department of Kinesiology, Physiology and Medicine Abstract Methods Results Results (continued) It was the aim of this study to explore the pressor responses to two Influence of the active muscle mass on the pressor response Treadmill Exercise Testing Systolic Blood Pressure (Slope) modes of dynamic exercise in older adults of differing genders and fitness levels. First, to evaluate the direct relationship between the Each participant performed a graded treadmill exercise test to peak 60 In response to exercise there were increases in systolic and size of the active muscle mass and the magnitude of the blood effort. Using a modified Balke protocol the procedure consisted of a 2 mean arterial blood pressure in both small muscle and large pressure response in the aged, and second, to determine if fitness minute warm-up at 2.5 mph followed by adjustment of the speed to 50 muscle exercises in all groups. This pressor response was more affects the blood pressure response in older adults in a mode or elicit ~75% of age-predicted peak heart rate after which the intensity pronounced during the small muscle knee extension exercise SBP Slope (SBP vs. MET) sex-specific manner. 37 normotensive healthy men and women of exercise (2% increase in elevation) increased every 2 minutes until 40 when compared to the large muscle treadmill running exercise. were recruited. Five low fit older men (71 ± 2 yr), 10 high fit older the participants reached volitional fatigue. 30 Influence of fitness and sex on treadmill pressor response in men (71 ± 2 yr), 12 low fit older women (67±1 yr), and 10 high fit Blood pressures were measured via brachial auscultation during the older adults older women (67±1 yr). All subjects performed treadmill and knee second minute of each exercise stage until participants indicated an 20 extensor exercise to fatigue on separate days. Systolic blood During the treadmill exercise fitness did not significantly affect effort level of 15 (“Hard”) or above on the Borg 6-20 rating of pressure and diastolic blood pressure were monitored and mean perceived exertion. Blood pressure measurements were not 10 the pressor response (SBP, DBP, and MAP). Therefore, we didn’t arterial blood pressure was calculated post-exercise. To evaluate attempted during peak effort to enable participants to fully engage see a significantly higher BP response in low fit older adults vs. the pressor response, blood pressure slope calculations were both arms and give maximum effort without disturbance. Pulmonary 0 high fit older adults. This was true for both men and women, so OM (HF) OM (LF) OW (HF) OW (LF) determined for Stage 1 through 4 for each exercise. So responses oxygen uptake (VO2) was measured using analysis of expired gases therefore there was no significant sex-specific fitness effect. The Age Group could be compared across exercises, and genders, all absolute by a Parvomedics metabolic cart (Sandy, Utah). pressor response for low fit older men did not significantly differ Treadmill pressures were normalized to working METs. Results showed that Knee Kick from low fit older women during the treadmill exercise. There all groups exhibited a more pronounced pressor response during was also no difference when comparing high fit older men and Knee Extensor Exercise Figure 1: mean systolic blood pressure slope values – absolute BP across working women. small muscle knee extensor exercise vs. large muscle treadmill METs, for both modes of exercise, genders, and fitness levels. exercise and fitness influenced the blood pressure response in Each participant performed single leg knee extensor exercise as Diastolic Blood Pressure (Slope) Influence of fitness and sex on knee extensor pressor response older adults in a mode and sex-specific manner – only during knee described previously [1,22]. To begin, participants were seated in a in older adults extensor exercise, and only in men. semi-reclined position with knees flexed at an angle of 90. To avoid extraneous movement during the exercise participant’s torso and 20 During the knee extensor exercise fitness affected the pressor thighs were strapped to the chairs. Knee extensions through a response in older adults - in a sex-specific way. Thus, we see a nearly full range of motion (90–170) were performed at 40 Purpose fitness effect in men, but not in women. Although high fit older DBP Slope (DBP vs. MET) 15 contractions per minute with the left foot placed in a boot that was men did show a significantly lower BP response when compared connected to the pedal arm of a cycle ergometer (Monark) that was to low fit older men, low fit older women did have the highest placed behind the subject. The exercise protocol consisted of three The purpose of the current investigation was to explore the 10 response compared to all groups. minute stages. The first stage consisted of quiet rest, followed by systolic, diastolic, and mean arterial blood pressure responses - unloaded passive exercise (manual external movement of lower defined by the slope values: absolute blood pressure across leg), knee extensions against no resistance (0 W), and finally working METs - to two modes of dynamic exercise in older men and women of different fitness levels. Firstly, we wanted to conduct extensions as resistance increased incrementally until the subject could no longer maintain cadence. After each three minute stage 5 Discussion a focused observation on how the pressor responses compared work rate increased by 10 W for men and 5 W for women. between two modes of dynamic work and ask whether the 0 OM (HF) OM (LF) OW (HF) OW (LF) The effects of an increased, or exaggerated pressor response to response was determined by the active muscle, i.e. whether it Blood pressures were measured continuously at rest and during exercise, in healthy people has important consequences in Age Group might be more pronounced during knee extensor exercise exercise using radial tonometry of the right hand (Colin CBM-7000, cardiovascular disease such as coronary heart disease. Many Treadmill compared to treadmill in the aged. Secondly, we wanted to know if Medical Instruments Corporation). The accuracy of the automated Knee Kick studies have looked at this exaggerated blood pressure response the heightened exercise blood pressure response normally seen in blood pressure measurement was checked against manual to graded dynamic exercise in healthy people and have found it Figure 2: mean diastolic blood pressure slope values – absolute BP across working older individuals was fitness dependent, i.e. to determine if an auscultation taken every three minutes during exercise. All variables METs, for both modes of exercise, genders, and fitness levels. to be a predictor of future hypertension and risk of cardiovascular increase in fitness level modulates the heightened blood pressure were collected on-line at a sampling frequency of 400 Hz and stored mortality response seen in older men and women, and if this fitness effect is Mean Arterial Blood Pressure (Slope) using a Powerlab system (AD Instruments, Castle Hill, Australia). mode or sex-specific. With respect to mode, one might ask why we see fitness affecting 30 the pressor response in the knee extensor exercise, but not the treadmill exercise. Why do we see a fitness effect during small muscle exercise and not during whole-body? In regards to gender, Participants Data Analysis 25 why don’t we see a sex-specific fitness influence in the old during MAP Slope (MAP vs. MET) 20 whole-body exercise, but do so with small muscle exercise? In essence, why are the influences of fitness in older adults absent Four groups of participants were recruited. Five low fit older men (71 All blood pressure calculations were derived from average values 15 for the treadmill exercise, but present, with a sex-specific element, ± 2 yr), 10 high fit older men (71 ± 2 yr), 12 low fit older women (67±1 taken over the last minute of rest, passive exercise, and each work during one-legged knee extensor exercise? 10 yr), and 10 high fit older women (67±1 yr). All participants had a rate. Mean arterial pressure (MAP, in mm Hg) was calculated as resting blood pressure < 140/90 mmHg, and were apparently healthy (1/3 systolic pressure) + (2/3 diastolic pressure). One important consideration is the method of data analysis, i.e. as evaluated by medical history questionnaire, a physical 5 the way we defined the pressor response; the slope, or the examination, and resting electrocardiogram. All participants provided In an effort to normalize the data and make slope comparisons absolute blood pressures across working METs. As far as we can written consent to participate in the study after receiving an across exercises blood pressures were compared not across 0 OM (HF) OM (LF) OW (HF) OW (LF) tell this is novel way to define a blood pressure response to explanation of the experimental procedures and possible risks stages, work load, or even time, but across MET. dynamic exercise. Although it was useful in making unique mode Age Group associated with participation. This study was approved by the Office Treadmill (and gender –within the knee extensor exercise) comparison it for Research Protections at Pennsylvania State University in Knee Kick may very well be ineffective in delineating fitness influences agreement with the guidelines set forth by the Declaration of Helsinki. during whole-body exercise. Figure 3: mean MAP slope values – absolute BP across working METs, for both modes of exercise, genders, and fitness levels.