Endurance exercise promotes cardiorespiratory rehabilitation without neurorestoration in the chronic mouse model of parkinsonism with severe neurodegeneration.

Physical rehabilitation with endurance exercise for patients with Parkinson's disease has not been well established, although some clinical and laboratory reports suggest that exercise may produce a neuroprotective effect and restore dopaminergic and motor functions. In this study, we used a chronic mouse model of Parkinsonism, which was induced by injecting male C57BL/6 mice with 10 doses of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (25 mg/kg) and probenecid (250 mg/kg) over 5 weeks. This chronic parkinsonian model displays a severe and persistent loss of nigrostriatal neurons, resulting in robust dopamine depletion and locomotor impairment in mice. Following the induction of Parkinsonism, these mice were able to sustain an exercise training program on a motorized rodent treadmill at a speed of 18 m/min, 0 degrees of inclination, 40 min/day, 5 days/week for 4 weeks. At the end of exercise training, we examined and compared their cardiorespiratory capacity, behavior, and neurochemical changes with that of the probenecid-treated control and sedentary parkinsonian mice. The resting heart rate after 4 weeks of exercise in the chronic parkinsonian mice was significantly lower than the rate before exercise, whereas the resting heart rate at the beginning and 4 weeks afterward in the control or sedentary parkinsonian mice was unchanged. Exercised parkinsonian mice also recovered from elevated electrocardiogram R-wave amplitude that was detected in the parkinsonian mice without exercise for 4 weeks. The values of oxygen consumption, carbon dioxide production, and body heat generation in the exercised parkinsonian mice before and during the Bruce maximal exercise challenge test were all significantly lower than that of their sedentary counterparts. Furthermore, the exercised parkinsonian mice demonstrated a greater mass in the left ventricle of the heart and an increased level of citrate synthase activity in the skeletal muscles. The amphetamine-induced, dopamine release-dependent locomotor activity was markedly inhibited in the sedentary parkinsonian mice and was also inhibited in the exercised parkinsonian mice. Finally, neuronal recovery from the loss of nigrostriatal tyrosine hydroxylase expression and dopamine levels in the severe parkinsonian mice after exercise was not evident. Taken all together, these data suggest that 4 weeks of treadmill exercise promoted physical endurance, resulting in cardiorespiratory and metabolic adaptations in the chronic parkinsonian mice with severe neurodegeneration without demonstrating a restorative potential for the nigrostriatal dopaminergic function.

Children with cerebral palsy have uncharacteristic somatosensory cortical oscillations after stimulation of the hand mechanoreceptors.

Numerous clinical investigations have reported that children with cerebral palsy (CP) have tactile discrimination deficits that likely limit their ability to plan and manipulate objects. Despite this clinical awareness, we still have a substantial knowledge gap in our understanding of the neurological basis for these tactile discrimination deficits. Previously, we have shown that children with CP have aberrant theta-alpha (4-14 Hz) oscillations in the somatosensory cortices following tactile stimulation of the foot. In this investigation, we evaluated if these aberrant theta-alpha oscillations also extend to the hand. Magnetoencephalography was used to evaluate event-related changes in the theta-alpha and beta (18-34 Hz) somatosensory cortical oscillations in groups of children with CP and typically developing (TD) children following tactile stimulation of their hands. Our results showed that the somatosensory theta-alpha oscillations were relatively intact in children with CP, which is in contrast to our previous results for foot tactile stimulations. We suspect that these inter-study differences may be related to the higher probability that the neural tracts serving the lower extremities are damaged in children with CP, compared to those serving the upper extremities. This inference is plausible since the participating children with CP had Manual Ability Classification System (MACS) levels between I and II. In contrast to the theta-alpha results, children with CP did exhibit a sharp increase in beta activity during the same time period, which was not observed in TD children. This suggests that children with CP still have deficits in the computational aspect of somatosensory processing.

Spanning set defines variability in locomotive patterns.

The purpose of the investigation was to use the spanning set methodology to quantify variability in locomotive patterns and to compare this method with traditional measures of variability. Subjects ran on a treadmill while sagittal plane kinematic data were collected with a high-speed (180 Hz) camera. Changes in variability were evaluated as the subject ran barefoot and in shoes. Mean ensemble curves for the knee angle during the stance period were created for each condition. From these curves, traditional measures of variability were calculated using the coefficients of variation (CVs), and the mean deviation (MD). Spanning set vectors were defined from the coefficients of polynomials that were fitted to the respective standard deviation curves. The magnitude of the spanning set was determined by calculating the norm of the difference between the two vectors. The normalised difference between the two conditions was 6.6%, 6.9% and 98%, for the MD, CV and spanning sets, respectively. The results indicated that the spanning set was capable of statistically (p < 0.05) determining differences in variability between the two conditions. CV and MD measures were unable to detect statistical differences (p > 0.05) between the two conditions. The spanning set provides an alternative, and sensitive measure for evaluating differences in variability from the mean ensemble curve.

Subtalar and knee joint interaction during running at various stride lengths.

AIM: It has been suggested that during running proper coordination between subtalar pronation/supination and knee flexion/extension via tibial rotation is important to attenuate ground reaction impact forces (GRIF). Lack of coordination over time may produce a wide range of injuries. It was hypothesized that increasing stride length would result in higher GRIF. It was also hypothesized that alterations in stride length would result in changes of the subtalar/knee coordination. METHODS: Six subjects ran under 3 different stride lengths (normal stride, understride and overstride) at their self-selected pace. Sagittal, rear view kinematic data and GRIF kinetic data were collected. The subtalar/knee coordination was evaluated via timing and relative velocity measures. Repeated measures ANOVA were performed on these measures with a Tukey post-hoc analysis conducted where appropriate (p<0.01). RESULTS: Increased stride length produced significant increases in GRIF and significantly augmented the differences between rearfoot and knee angular velocities. A change in the rearfoot angle curve from a unimodal (1 minimum) to a bimodal (2 minimums) parabolic configuration was also observed. The appearance of the additional minimum was attributed to the increased impact with the ground. CONCLUSION: The results indicated that increases in GRIF via changes in stride length could disrupt the coordination between subtalar and knee joint actions.