The influence of dynamic visual environments on postural sway in the elderly

1999 ◽  
Vol 9 (3) ◽  
pp. 197-205
Author(s):  
L.L. Borger ◽  
S.L. Whitney ◽  
M.S. Redfern ◽  
J.M. Furman
Keyword(s):  
Visual Information ◽  
Postural Sway ◽  
Center Of Pressure ◽  
Age Groups ◽  
The Elderly ◽  
Visual Scene ◽  
Elderly Subjects ◽  
Mean Velocity ◽  
Healthy Elderly ◽  
Young Subjects

Postural sway during stance has been found to be sensitive to moving visual scenes in young adults, children, and those with vestibular disease. The effect of visual environments on balance in elderly individuals is relatively unknown. The purpose of this study was to compare postural sway responses of healthy elderly to those of young subjects when both groups were exposed to a moving visual scene. Peak to peak, root mean squared, and mean velocity of the center of pressure were analyzed under conditions combining four moving scene amplitudes ( 2 . 5 ∘ , 5 ∘ , 7 . 5 ∘ , 10 ∘ ) and two frequencies of scene movement (0.1 Hz, 0.25 Hz). Each visual condition was tested with a fixed floor and sway referenced platform. Results showed that elderly subjects swayed more than younger subjects when experiencing a moving visual scene under all conditions. The elderly were affected more than the young by sway referencing the platform. The differences between the two age groups were greater at increased amplitudes of scene movement. These results suggest that elderly are more influenced by dynamic visual information for balance than the young, particularly when cues from the ankles are altered.

Effect of ‘Autonomic Blockade’ on Cardiac β-Adrenergic Chronotropic Responsiveness in Healthy Young, Healthy Elderly and Endurance-Trained Elderly Subjects

1994 ◽  
Vol 87 (3) ◽  
pp. 297-302 ◽  
Author(s):  
G. A. Ford ◽  
O. F. W. James
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Geometric Mean ◽  
Cardiovascular Responses ◽  
The Elderly ◽  
Elderly Subjects ◽  
Healthy Elderly ◽  
Age Related ◽  
Autonomic Blockade ◽  
Young Subjects

1. Cardiac chronotropic responses to isoprenaline are reduced with ageing in man. It is unclear whether this is due to reduced cardiac β-adrenergic sensitivity or to age-associated differences in reflex cardiovascular responses to the vasodilatory effects of isoprenaline. Age-associated changes in physical activity are also reported to influence β-adrenergic sensitivity. 2. The aim of the present study was to determine the contribution of alterations in reflex changes in parasympathetic and sympathetic influences and physical fitness to the age-associated reduction in cardiac chronotropic responses to β-adrenergic agonists. 3. The effect of ‘autonomic blockade’ with atropine (40 μg/kg intravenously) and clonidine (4 μg/kg intravenously) on blood pressure, heart rate and chronotropic responses to intravenous bolus isoprenaline doses was determined in eight healthy young (mean age 21 years), nine healthy elderly (72 years) and 10 endurance-trained elderly (69 years) subjects. 4. Elderly subjects had a reduced increase in heart rate after atropine (young, 49 ± 9 beats/min; elderly, 36 ± 5 beats/min; endurance-trained elderly, 34 ± 12 beats/min; P < 0.01) and did not demonstrate the transient increase in systolic blood pressure after clonidine observed in young subjects (young, 11 ± 10 mmHg; elderly, −12 ± 16 mmHg; endurance-trained elderly, −18 ± 11 mmHg; P < 0.01). 5. Cardiac chronotropic sensitivity to isoprenaline after ‘autonomic blockade’ increased in the young but decreased in the elderly subjects. The isoprenaline dose that increased heart rate by 25 beats/min before and after autonomic blockade' was: young, before 1.6 μg, after 2.8 μg, P < 0.01 (geometric mean, paired test); elderly, before 6.9 μg, after 3.6 μg, P < 0.05; endurance-trained elderly, before 5.9 μg, after 4.0 μg, P < 0.05. Cardiac chronotropic sensitivity to isoprenaline was significantly reduced in elderly compared with young subjects before (P < 0.01) but was similar after (P = 0.09) ‘autonomic blockade’. Chronotropic sensitivity did not differ between healthy and endurance-trained elderly subjects before or after ‘autonomic blockade’. 6. The age-associated reduction in cardiac chronotropic responses to bolus isoprenaline is primarily due to an age-related reduction in the influence of reflex cardiovascular responses on heart rate and not to an age-related reduction in cardiac β-adrenergic sensitivity. Endurance training is not associated with altered β-adrenergic chronotropic sensitivity in the elderly. The transient pressor response to intravenously administered clonidine may be lost in ageing man.

Nonexercise movement in elderly compared with young people

2007 ◽  
Vol 292 (4) ◽  
pp. E1207-E1212 ◽  
Author(s):  
Ann M. Harris ◽  
Lorraine M. Lanningham-Foster ◽  
Shelly K. McCrady ◽  
James A. Levine
Keyword(s):  
Energy Expenditure ◽  
Lean Body Mass ◽  
Body Mass ◽  
The Elderly ◽  
Energetic Cost ◽  
Elderly Subjects ◽  
Older Individuals ◽  
Free Living ◽  
Healthy Elderly ◽  
Young Subjects

The association between free-living daily activity and aging is unclear because nonexercise movement and its energetic equivalent, nonexercise activity thermogenesis, have not been exhaustively studied in the elderly. We wanted to address the hypothesis that free-living nonexercise movement is lower in older individuals compared with younger controls matched for lean body mass. Ten lean, healthy, sedentary elderly and 10 young subjects matched for lean body mass underwent measurements of nonexercise movement and body posture over 10 days using sensitive, validated technology. In addition, energy expenditure was assessed using doubly labeled water and indirect calorimetry. Total nonexercise movement (acceleration arbitrary units), standing time, and standing acceleration were significantly lower in the elderly subjects; this was specifically because the elderly walked less distance per day despite having a similar number of walking bouts per day compared with the young individuals. The energetic cost of basal metabolic rate, thermic effect of food, total daily energy expenditure, and nonexercise activity thermogenesis were not different between the elderly and young groups. Thus, the energetic cost of walking in the elderly may be greater than in the young. Lean, healthy elderly individuals may have a biological drive to be less active than the young.

Down training of the elderly soleus H reflex with the use of a spinally induced balance perturbation

2002 ◽  
Vol 93 (1) ◽  
pp. 127-133 ◽  
Author(s):  
Richard G. Mynark ◽  
David M. Koceja
Keyword(s):  
Postural Stability ◽  
Balance Training ◽  
The Elderly ◽  
Static Stability ◽  
H Reflex ◽  
Spinal Reflex ◽  
Elderly Subjects ◽  
Healthy Elderly ◽  
Young Subjects ◽  
Healthy Elderly Subjects

The purpose of this study was to determine the ability of the elderly central nervous system to modulate spinal reflex output to functionally decrease a spinally induced balance perturbation. In this case, the soleus H reflex was used as the source of perturbation. Therefore, decreasing (down training) of the soleus H reflex was necessary to counteract this perturbation and to better maintain postural control. In addition to assessing the effect of this perturbation on the H reflex, static postural stability was measured to evaluate possible functional effects. Ten healthy young subjects (age: 27.0 ± 4.6 yr) and 10 healthy elderly subjects (age: 71.4 ± 5.1 yr) participated in this study. Subjects underwent balance perturbation on 2 consecutive days. On day 1 of perturbation, significant down training of the soleus H reflex was demonstrated in both young (−20.4%) and elderly (−18.7%) subjects. On day 2 of perturbation, significant down training of the soleus H reflex was again demonstrated in both young (−24.6%) and elderly (−21.0%) subjects. Analysis of static stability after the 2 days of balance perturbation revealed a significant 10.1% decrease in the area of sway in elderly subjects. In conclusion, this study demonstrated that healthy, elderly subjects compared with young subjects were equally capable of down training the soleus H reflex in response to a balance perturbation. Furthermore, the improvement in static stability through balance training may provide further evidence that balance can be retrained and rehabilitated in subjects with decreased reflex function.

Disparities in circulatory adjustment to standing between young and elderly subjects explained by pulse contour analysis

1992 ◽  
Vol 83 (2) ◽  
pp. 149-155 ◽  
Author(s):  
W. Wieling ◽  
D. P. Veerman ◽  
J. H. A. Dambrink ◽  
B. P. M. Imholz
Keyword(s):  
Blood Pressure ◽  
Heart Rate ◽  
Total Peripheral Resistance ◽  
Age Groups ◽  
Peripheral Resistance ◽  
The Elderly ◽  
Pulse Contour ◽  
Elderly Subjects ◽  
Orthostatic Stress ◽  
Young Subjects

1. The circulatory adjustment to standing was investigated in two age groups. Young subjects consisted of 20 healthy 10–14-year-old girls and boys. Elderly subjects consisted of 40 70–86-year-old healthy and active females and males. Continuous responses of blood pressure and heart rate were recorded by Finapres. A pulse contour algorithm applied to the finger arterial pressure waveform was used to assess stroke volume responses. 2. During the first 30 s (initial phase), an almost identical drop in mean blood pressure was found in both age groups (young, 16 ± 10 mmHg; old, 17 ± 10 mmHg), but the initial heart rate increase was attenuated in the elderly subjects (young, 29 ± 7 beats/min; old, 17 ± 7 beats/min). 3. During the period from 30 s to 10 min of standing, mean blood pressure increased from 96 ± 12 to 106 ± 12 mmHg in the elderly subjects compared with almost no change in the young subjects (from 82 ± 8 to 84 ± 7 mmHg). In the elderly subjects a progressive increase in total peripheral resistance (from 114 ± 14% to 146 ± 29%) was found, compared with an initial rapid increase in total peripheral resistance (126 ± 18% after 30 s) with no further change during prolonged standing (124 ± 17% after 10 min) in the young subjects. In this age group the decrease in stroke volume and the increase in heart rate after 10 min of standing were large (young, −37 ± 11% and 27 ± 11 beats/min; old, −31 ± 9% and 7 ± 6 beats/min, respectively). 4. In conclusion, young subjects adjust to orthostatic stress mainly by a marked increase in heart rate. In healthy elderly subjects an attenuation of the heart rate response during orthostatic stress is compensated by a pronounced increase in total peripheral resistance resulting in an increase in blood pressure.

Walking with Visual Restrictions in Healthy Elderly and Young Adults

2002 ◽  
Vol 21 (2) ◽  
pp. 295-301 ◽  
Author(s):  
Sean Gallagher ◽  
Yves Lajoie ◽  
Michel Guay
Keyword(s):  
Young Adults ◽  
Visual Information ◽  
Older Persons ◽  
Visual Cues ◽  
Elderly Population ◽  
The Elderly ◽  
Elderly Subjects ◽  
Elderly Persons ◽  
Experimental Conditions ◽  
Healthy Elderly

ABSTRACTVisual requirements for a simple walking task were evaluated for young and elderly persons to determine if, with normal aging, elderly subjects require more visual information. Ten young adults and 10 elderly people were asked to complete a simple walking task within predetermined pathway boundaries under two conditions of visual restriction. In the reactive condition, subjects automatically received a 200 ms flash of visual information at the halfway point of the walkway. For the predictive condition, subjects did not receive any visual information during the walking trial, but were equipped with an emergency button that would provide 200 ms of visual information whenever they needed it. For both experimental conditions, subjects received additional flashes of visual information if they stepped out of the walkway boundaries. Results showed that older persons stepped out of bounds more often in the reactive condition and gave themselves more visual cues than the younger subjects in the predictive condition. The relative importance of vision during locomotion seems to be higher in the elderly population when compared to young adults.

Ventilatory and arousal patterns during sleep in normal young and elderly subjects

1985 ◽  
Vol 59 (5) ◽  
pp. 1607-1615 ◽  
Author(s):  
E. T. Shore ◽  
R. P. Millman ◽  
D. A. Silage ◽  
D. C. Chung ◽  
A. I. Pack
Keyword(s):  
Sleep Apnea Syndrome ◽  
Age Groups ◽  
Periodic Breathing ◽  
The Elderly ◽  
Elderly Subjects ◽  
Sleep State ◽  
Respiratory Inductive Plethysmography ◽  
State Dependent ◽  
Young Subjects ◽  
Stage 1

Since elderly subjects have lower chemosensitivity, we postulated that ventilation might be more state dependent in the elderly. To address this we investigated the changes in ventilation, measured by respiratory inductive plethysmography, with sleep in 12 healthy young (19–29 yr) and 13 elderly (greater than 65 yr) subjects. Ventilation was measured in representative periods in each sleep state. These data showed that there is no difference between the elderly and the young either in mean ventilation or in the variability of ventilation awake or in the different states of sleep. In both groups ventilation was variable in stage 1–2 sleep and least variable in stage 3–4 sleep. The variability in stage 1–2 sleep was due to periodic breathing (cycle time approximately 45 s) in both age groups. Although within a sleep state no differences were observed, over the night of study the elderly behaved differently from the young. Apneas occurred more frequently in the elderly, and 5 of 13 elderly met the criteria for sleep apnea syndrome compared with 1 of 12 young subjects. Apneas tended to occur predominantly in stage 1–2 sleep and seem to be an exaggeration of the periodicity that is typical of this state. Four of the elderly with apnea remained in this stage of sleep throughout the night of study. The apneic episodes usually terminated with an electroencephalogram arousal that occurred prior to or simultaneously with the onset of ventilation.

Postural Sway and Perception of the Upright Stance Stability Borders

Perception ◽  
1993 ◽  
Vol 22 (11) ◽  
pp. 1333-1341 ◽  
Author(s):  
Janusz W Blaszczyk ◽  
Paul D Hansen ◽  
Deborah L Lowe
Keyword(s):  
Postural Stability ◽  
Postural Sway ◽  
Age Groups ◽  
The Elderly ◽  
Stability Control ◽  
Center Of Gravity ◽  
Elderly Subjects ◽  
Experimental Conditions ◽  
Eyes Closed ◽  
Eyes Open

Decline in the perception of the borders of postural stability due to increase in sway was evaluated in young and elderly subjects. Ranges of lateral and anteroposterior postural sway were measured in eleven young and eleven elderly subjects during maximum voluntary excursions of center of gravity while leaning forward, backward, left, and right. In both age groups, displacement of the center of gravity out of the reference position resulted in increases in the range of sway in the plane corresponding to the direction of lean. Young subjects who further displaced their center of gravity within the base of support also exhibited significantly elevated anteroposterior sway range while leaning forward and backward, both in eyes-closed and in eyes-open experimental conditions. The elderly subjects, however, showed greater mediolateral oscillation of center of gravity while leaning forward with their eyes open. No significant intergroup differences in the anteroposterior sway range during leans in the mediolateral plane were found. However, a greater mediolateral component of sway range at lateral borders of stability was observed in the young adults. Analysis of signal-to-noise ratios indicated a greater decline in stability control in the elderly, due to impairment of perception of postural stability borders.

Haemodynamic Responses in Young and Elderly, Healthy Subjects during Ambient and Warm Head-up Tilt

1998 ◽  
Vol 94 (5) ◽  
pp. 493-498 ◽  
Author(s):  
Michael Lye ◽  
Tom Walley
Keyword(s):  
Skin Temperature ◽  
Postural Hypotension ◽  
The Elderly ◽  
Young Group ◽  
Elderly Subjects ◽  
Healthy Elderly ◽  
Head Up Tilt ◽  
Blood Pressures ◽  
Young Subjects ◽  
Qualitative Responses

1. Postural hypotension is common in elderly people and is usually multifactorial in origin. In young subjects increased ambient temperature is associated with postural symptoms. We hypothesized that such increases in skin temperature due to the use of bed clothes might contribute to nocturnal postural hypotension in the elderly. We therefore studied haemodynamic responses to head-up tilt in healthy elderly and young subjects, with and without passive heating induced by covering with blankets. 2. Nine young (28.7 ± 1.5 years; mean ± S.E.M.) and nine elderly (71.9 ± 1.8 years) subjects were studied. All had been carefully screened to exclude factors likely to affect responses to tilt. All subjects underwent a standard head-up tilt procedure at ambient room temperature while haemodynamic responses were monitored. The subjects were then covered in blankets for 55 min and the tilt repeated. Skin temperature before the second tilt had increased from approximately 32.5 °C to approximately 35.2 °C (P < 0.001). 3. The elderly subjects maintained higher blood pressures throughout both tilts (P < 0.001) and both groups showed similar qualitative responses to tilt. Supine heart rates were higher in the elderly group (P < 0.01) with a tendency to increase more in the young group in response to tilt, especially while warm (P = 0.370). Stroke volumes and cardiac indices were consistently higher in the young group who showed larger changes during both head-up tilts. In both groups the haemodynamic responses to ambient and warm tilt were essentially the same. 4. Healthy elderly subjects, who are carefully screened to exclude individuals with cardiovascular pathology, respond to head-up tilt in the same qualitative fashion as young subjects. Quantitative responses in older subjects are ‘damped’. Short-term natural body warming does not impair the reflexes in young or old subjects.

scholarly journals Renal functional reserve in healthy elderly subjects.

1993 ◽  
Vol 3 (7) ◽  
pp. 1371-1377
Author(s):  
D Fliser ◽  
M Zeier ◽  
R Nowack ◽  
E Ritz
Keyword(s):  
Renal Disease ◽  
The Elderly ◽  
Renal Hemodynamics ◽  
Elderly Subjects ◽  
Functional Reserve ◽  
Renal Functional Reserve ◽  
Healthy Elderly ◽  
Age Related ◽  
Before And After ◽  
Young Subjects

The increase in GFR after an amino acid (AA) load, the so-called renal functional reserve, is impaired in the aged rat. Whether the renal functional reserve predicts the progression of renal disease in humans is controversial, but it is possible that age-related alterations of renal hemodynamics are relevant for the evolution of renal disease in the elderly. We compared renal hemodynamics before and after an AA infusion in 15 healthy normotensive subjects of young age (seven women, eight men; median age, 26 yr; range, 23 to 32) and in 10 subjects of old age (six women, four men; median age, 70 yr; range, 61 to 82) on normal dietary protein intake. Baseline GFR and effective RPF were measured after 12 h of fasting by the inulin (Cin) and para-aminohippurate (Cpah) steady-state infusion techniques. The renal functional reserve was examined after an overnight AA infusion (7% solution; 83 mL/h). Median basal Cin and Cpah were significantly lower (P < 0.01) in the elderly (102 and 339 mL/min per 1.73 m2) than in the young subjects (122 and 647 mL/min per 1.73 m2), but virtually all GFR values of the elderly were still within the normal range. Median Cin upon infusion of AA was 118 mL/min per 1.73 m2 (range, 98 to 137) in the elderly and 146 (range, 120 to 171) in the young, respectively. Corresponding values of Cpah were 349 mL/min per 1.73 m2 in the elderly versus 689 mL/min per 1.73 m2 in the young. Cin increased significantly (P < 0.01) after the AA load in both young and elderly subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

Atrial natriuretic factor in the elderly: diminished response to epinephrine

1989 ◽  
Vol 257 (6) ◽  
pp. E866-E870 ◽  
Author(s):  
L. A. Morrow ◽  
G. S. Morganroth ◽  
T. J. Hill ◽  
J. A. Sanfield ◽  
S. G. Rosen ◽  
...  
Keyword(s):  
Atrial Natriuretic Factor ◽  
Human Subjects ◽  
The Elderly ◽  
Elderly Subjects ◽  
Adrenergic Stimulation ◽  
Healthy Elderly ◽  
Natriuretic Factor ◽  
Young Subjects ◽  
Healthy Elderly Subjects ◽  
Atrial Natriuretic

We have previously found that epinephrine (EPI) increases plasma immunoreactive atrial natriuretic factor (irANF) in young human subjects. Because elderly humans have decreased sensitivity to adrenergic stimulation, we compared plasma irANF responses to intravenous infusion of EPI, 5 micrograms/min for 80 min in six young (ages 20-29) and nine old (ages 62-75) healthy subjects. In addition, we measured plasma irANF responses of the nine old subjects to 1 liter of normal saline infused over 30 min. Young and old subjects had similar basal EPI levels [108 +/- 18 vs. 106 +/- 10 (SE) pg/ml], but basal irANF levels tended to be higher in the old (32 +/- 7 vs. 50 +/- 8 pmol/l, P = 0.15). The young subjects had a significant increase in irANF levels after the EPI infusion (32 +/- 7 vs. 59 +/- 11 pmol/l, P less than 0.02), but there was no change in irANF in the old (50 +/- 8 vs. 48 +/- 7 pmol/l) despite similar plasma EPI levels in young and old (1,125 +/- 57 vs. 1,183 +/- 52 pg/ml). In contrast, the irANF response of the old subjects to saline infusion was striking: all nine subjects demonstrated a rise in irANF (P less than 0.01); mean levels increased from 54 +/- 4 pmol/l to a peak of 122 +/- 23 pmol/l. We conclude that healthy elderly subjects have a defect in EPI-stimulated ANF secretion, a finding compatible with other evidence for diminished sensitivity to adrenergic stimulation in aging.(ABSTRACT TRUNCATED AT 250 WORDS)

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