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.