The journals of gerontology. Series A, Biological sciences and medical sciences
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J. Gerontol. A Biol. Sci. Med. Sci. · Mar 1998
Soleus H-reflex gain in elderly and young adults: modulation due to body position.
The control of posture and balance in the elderly is a primary health concern. Postural instability directly leads to a greater incidence of falling in the elderly population. One important neuromuscular mechanism instrumental in the control of posture and balance is the reflex system. The purpose of this study was to examine the gain of the soleus H-reflex in young and elderly adults in two different body positions: standing and prone. ⋯ The results demonstrate different control strategies for young and elderly subjects between prone and standing body positions.
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J. Gerontol. A Biol. Sci. Med. Sci. · May 1997
ReviewA systematic review of the evidence for hypodermoclysis to treat dehydration in older people.
The purpose of the study was to evaluate the evidence supporting the use of hypodermoclysis (i.e., subcutaneous infusion of fluids) to treat dehydrated elderly patients, and to discuss clinical applications of this mode of therapy in the long-term care setting. ⋯ Hypodermoclysis can be used to most safely provide fluids when electrolyte-containing fluids are administered. Hypodermoclysis may have fallen into disuse because of reports of severe adverse reactions related to infusions of electrolyte-free or hypertonic solutions that would likely be considered inappropriate today. Whether or not hyaluronidase is required to promote subcutaneous fluid absorption remains unresolved. Limited evidence suggests that potassium chloride may, with caution, be safely added to subcutaneous infusions. The majority of the available studies evaluating hypodermoclysis are of poor quality. Because of the tremendous potential benefits of administering fluid subcutaneously, there is a need for good quality studies to evaluate the efficacy of hypodermoclysis.
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J. Gerontol. A Biol. Sci. Med. Sci. · Jan 1997
Age differences in using a rapid step to regain balance during a forward fall.
Earlier studies showed that healthy old adults have substantially reduced abilities to develop joint torques rapidly. We hypothesized that this age decline would reduce abilities to regain balance once a forward fall is underway. The present study examined whether aging in fact reduces ability to regain balance by taking a single, rapid step upon release from a forward lean. ⋯ Substantial age-related declines in the ability to regain balance by taking a rapid step exist among healthy adults when the time available for recovery is short. The source of the decline seems largely to lie in the decrease with age of maximum response execution speed rather than in the sensory or motor programming processes involved in response initiation.
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J. Gerontol. A Biol. Sci. Med. Sci. · Nov 1996
Step length reductions in advanced age: the role of ankle and hip kinetics.
Aging is associated with a reduction in gait velocity, which is due to a shortened step length. This study investigated the relationship between joint kinetics and step length. ⋯ Older subjects had lower ankle plantarflexor power during the late stance phase of gait and appeared to compensate for reductions in plantarflexor power by increasing hip flexor power. Appropriate training of ankle plantarflexor muscles may be important in maintaining step length in advanced age.
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J. Gerontol. A Biol. Sci. Med. Sci. · Sep 1996
Suppression of first pain and slow temporal summation of second pain in relation to age.
Thermal stimuli delivered to skin of the arms or legs can produce a sensation of two distinct pains. These pains have been associated with activity in A-delta (first pain) and C-fiber (second pain) nociceptive fibers, respectively. Under appropriate conditions first pain decreases in intensity (adaptation) while second pain increases in intensity (slow temporal summation). Change in first and second pain to repeated stimulation of skin has not been assessed in relation to age. ⋯ Age did not influence pain intensity to unadapted and unsensitized skin. Slow temporal summation of second pain was not observed at the leg in the older group, suggesting that mechanisms subserving C-fiber mediated sensitization of second order nociceptive neurons may fail with age. Longer response times to first, but not second pain in older subjects may represent an age effect on myelinated (A-delta; first pain) and not unmyelinated (C-fiber; second pain) nociceptive afferents and may represent a type of small fiber peripheral neuropathy.