Spinal and corticospinal pathways are differently modulated when standing at the bottom and the top of a three-step staircase in young and older adults

Purpose This study investigated the modulation of spinal (group Ia afferents) and corticospinal pathways when young (22.7 ± 1.3 years) and older adults (72.2 ± 7.9 years) stood at the bottom and at the top of a three-step staircase equipped with force platforms. Method Changes in submaximal H -refle...

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Bibliographic Details
Published in:European journal of applied physiology 2017-06, Vol.117 (6), p.1165-1174
Main Authors: Johannsson, Johanna, Duchateau, Jacques, Baudry, Stéphane
Format: Article
Language:English
Subjects:
Aged
Aged, 80 and over
Aging - physiology
Balance
Biomedical and Life Sciences
Biomedicine
Evoked potentials
Evoked Potentials, Motor
Female
H-Reflex
Human Physiology
Humans
Magnetic fields
Male
Motor evoked potentials
Motor task performance
Muscle, Skeletal - growth & development
Muscle, Skeletal - innervation
Muscle, Skeletal - physiology
Occupational Medicine/Industrial Medicine
Older people
Original Article
Postural Balance
Posture
Pyramidal tracts
Pyramidal Tracts - growth & development
Pyramidal Tracts - physiology
Reflexes
Sports Medicine
Velocity
Young Adult
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Summary:Purpose This study investigated the modulation of spinal (group Ia afferents) and corticospinal pathways when young (22.7 ± 1.3 years) and older adults (72.2 ± 7.9 years) stood at the bottom and at the top of a three-step staircase equipped with force platforms. Method Changes in submaximal H -reflex amplitude ( H 50 ) and slope of the H -reflex input–output relation (spinal pathway), and in amplitude of motor-evoked potentials (MEP) triggered by transcranial magnetic stimulation (corticospinal pathway) at two intensities (1.1× and 1.2× motor threshold) were recorded in soleus when subjects stood as steady as possible downstairs and upstairs. The centre of pressure (CoP) excursion was analyzed in the time and frequency domains in both conditions. Results Regardless of age, the mean CoP velocity was greater when standing upstairs (11.1 ± 3.5 mm s −1 ) than downstairs (9.0 ± 2.3 mm s −1 ; p  = 0.002). The CoP power spectral density (PSD) in the 0–0.5 Hz band was greater upstairs than downstairs (+18.4%; p  = 0.03) whereas PSD in the 2–20Hz frequency band was lesser (−41%) upstairs than downstairs ( p  
ISSN:1439-6319
1439-6327
DOI:10.1007/s00421-017-3603-3