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M Udo

Publications and source records attributed to M Udo.

At least 37 records · Page 2Linked to original sources
PubMed1989

Physiological determinants of race walking performance in female race walkers.

The purpose of this study was to determine the relationship between race pace on a 5 km walking performance and velocity at the lactate threshold (V-LT), VO2 at the lactate threshold (VO2-LT), velocity at which blood lactate corresponded to 4 mM level (V-OBLA), VO2 at which blood lactate corresponded to 4 mM level (VO2-OBLA), walking economy (steady state VO2 at a standard velocity) and maximal oxygen uptake (VO2max) in eight female race walkers. A multiple stepwise linear regression analysis was employed to predict the race pace on a 5 km walking performance as dependent variable. Since V-OBLA was highly correlated to 5 km race walking performance (r = 0.94, P less than 0.001), it was selected as the first predictor. When VO2max was added to V-OBLA as the second predictor the predictive accuracy increased significantly, but multiple R did not increase significantly by adding variables of walking economy or other parameters as independent variance. As a result, the combination of V-OBLA and VO2max as independent variables accounted for the greatest amount of total variance (97 per cent). It is suggested that blood lactate variable such as V-OBLA can account for a large portion of the variance in race pace on a 5 km walking performance.

Adult↗
PubMed1985

Responses of cerebellar Purkinje cells to mechanical perturbations during locomotion of decerebrate cats.

During the locomotion of cats which had been decerebrated at the precollicular and premammillary level, mechanical perturbations (taps of 50-550 g wt.) were applied to the paw dorsum of the left forelimb. Purkinje cells were recorded from the vermis of the cerebellar anterior lobe, and those connected to Deiters' neurons controlling the right forelimb were identified by antidromic and orthodromic stimuli. Taps on the left forelimb induced in these Purkinje cells two types of responses; I-type is a depression of simple spike discharge, often preceded by a brief phase of facilitation, and E-type is entirely a facilitation of simple spike discharge. Complex spikes, representing activation through climbing fiber afferents, were frequently evoked by the taps in both I- and E-types. The I-type depression in Purkinje cells closely corresponds to the previously reported facilitation in Deiters' neurons and forelimb extensor muscles, suggesting that the interlimb coordination during cat's locomotion is effected by linked activity of vermal Purkinje cells and Deiters' neurons.

Animals↗
PubMed1982

Interlimb coordination in cat locomotion investigated with perturbation. I. Behavioral and electromyographic study on symmetric limbs of decerebrate and awake walking cats.

During locomotion of decerebrate and awake walking cats, perturbation (mechanical tap) was applied to the paw dorsum of the left forelimb (LF), and the responses of both forelimbs were recorded cinematographically and electromyographically (EMG). When the tap was applied during the LF stance phase, the duration of the ongoing LF stance was shortened by 10%; in the right forelimb (RF), the duration of the concomitant swing was shortened by 32%. A tap during the LF swing phase prolonged the duration of the ongoing LF swing phase and the concomitant RF stance phase by 55 and 15%, respectively. Analysis of RF joint angle excursions showed that the shortening of the RF swing phase was related mainly to acceleration of extension movement in the late swing phase; the prolongation of the RF stance phase was related to prolonged extension movement in the late stance phase. While EMG activities were relevant to these limb movements, a notable observation was that, by tapping the LF during the LF stance phase, EMG activity in the RF extensor started well before onset of the elbow extension movement to place down the limb; without the tap, the extensor activity started shortly after onset of the extension. Closely related to changes in phase durations of each forelimb, the period of bisupport phase where both forelimbs were in stance, was retained for more than 40% of that of unperturbed steps, even when the RF or LF made the first touchdown after the tap. The rostrocaudal level at RF touchdown after the tap was comparable to unperturbed steps. These findings on interlimb relation suggest that neural control ensures coordinated movements between symmetric limbs during locomotion.

Animals↗
PubMed1982

Interlimb coordination in cat locomotion investigated with perturbation. II. Correlates in neuronal activity of Deiter's cells of decerebrate walking cats.

The effects of mechanical stimulation (tap) on single unit activity of Deiter's neurons were analysed in walking cats decerebrated at the premammillary level. Deiters' neurons projecting to the ipsilateral cervical, but not to the lumbosacral, spinal cord (C-Deiters' neurons) were identified by antidromic activation, cerebellar stimulation, and localization of the neurons. During each unperturbed cycle of quadrupedal locomotion, most C-Deiters' neurons showed two frequency modulation peaks in their impulse discharges: one (A peak) in the late swing (E1) or the early stance (E2) phase, the other (B peak) in the late stance (E3) or the early swing (F) phase, of the ipsilateral forelimb. The A peak started to rise shortly before the ipsilateral forelimb was placed. When mechanical perturbation was applied during locomotion to the paw dorsum of the left forelimb (LF) in its stance phase, the ongoing LF stance phase shortened and the simultaneous swing phase of the right forelimb (RF) shortened. Accordingly, in the RF, extensor activity in the swing phase to place down the limb occurred earlier than in unperturbed step cycles. The same LF tap induced a marked enhancement of impulse discharges in C-Deiters' neurons on the right side (with a magnitude of 20-100 imp/s, and the shortest latency of 25 ms). This enhancement was more pronounced than that induced when the perturbation was applied to the LF during its swing phase. The latency manifested a close time relation to the RF extensor activity supporting the postulate that the increased C-Deiters' activity in the RF swing phase contributes to the earlier onset of RF extensor activity which plays an important role in maintaining alternating footfalls after perturbation.

Animals↗
PubMed1981

Simple and complex spike activities of Purkinje cells during locomotion in the cerebellar vermal zones of decerebrate cats.

In walking cats decerebrated at the premammillary level, single neurone activity of Purkinje cells (P-cells) with long corticofugal axons was recorded in the cerebellar vermis. The P-cells (N = 145) were identified as they showed spontaneous simple and complex spikes and also antidromic activation from Deiters' nucleus. These P-cells were classified into 6 groups according to the receptive fields of the climbing fibre responses (CFRs) which were evoked by electrical stimulation in each limb at the radial and sciatic nerve bundles. One group designated as forelimb units received the CFRs from both forelimbs and from neither hindlimb. According to previous studies, this group of P-cells is thought to make inhibitory connections with Deiters neurones projecting to the ipsilateral cervicothoracic spinal cord. For the forelimb units, two types of discharge patterns for simple spikes were found in relation to limb movements during locomotion. Type I cells showed one peak in their firing rate in the late swing (E1) or early stance (E2) phase of the ipsilateral forelimb. Type II cells showed two peaks and two valleys during one step cycle: one peak was in the E1 phase, the other in the late stance (E3) or early swing (F) phase; each of the two valleys followed the peak. Complex spikes of the forelimb units occurred more frequently in the E1 phase than during the other phases. The increased activity of simple and complex spikes of the forelimb units in the E2 phase is suggested to have a functional significance in preparing the appropriate floor reaction forces that appear upon touchdown on the ipsilateral forelimb.

Animals↗