A 12-Week Cycling Training Regimen Improves Upper Limb Functions in People With Parkinson's Disease.

Background: It has been proposed that physical exercise can help improve upper limb functions in Parkinson's disease (PD) patients; yet evidence for this hypothesis is limited. Objective: To assess the effects of aerobic exercise training (AET) on general upper limb functions in sedentary people with PD and healthy adults (HA). Methods: Two groups, 19 PD patients (Hoehn & Yahr ≤ 2) and 20 HA, matched on age and sedentary level, followed a 3-month stationary bicycle AET regimen. We used the kinematic theory framework to characterize and quantify the different motor control commands involved in performing simple upper-limb movements as drawing lines. Repeated measures ANCOVA models were used to assess the effect of AET in each group, as well as the difference between groups following the training regimen. Results: At baseline, PD individuals had a larger antagonist response, a longer elapsed time between the visual stimulus and the end of the movement, and a longer time of displacement of the stylus than the HA. Following the 12-week AET, PD participants showed significant decreases of the agonist and antagonist commands, as well as the antagonist response spread. A significant group ∗ session interaction effect was observed for the agonist command and the response spread of the antagonist command, suggesting a significant change for these two parameters only in PD patients following the AET. Among the differences observed at baseline, only the difference for the time of movement remained after AET. Conclusion: A 3-month AET has a significant positive impact on the capacity to draw lines in a more efficiency way, in PD patients, indicating an improvement in the upper limb motor function.

A 12-Week Cycling Training Regimen Improves Gait and Executive Functions Concomitantly in People with Parkinson's Disease.

Background: There is increasing evidence that executive functions and attention are associated with gait and balance, and that this link is especially prominent in older individuals or those who are afflicted by neurodegenerative diseases that affect cognition and/or motor functions. People with Parkinson's disease (PD) often present gait disturbances, which can be reduced when PD patients engage in different types of physical exercise (PE), such as walking on a treadmill. Similarly, PE has also been found to improve executive functions in this population. Yet, no exercise intervention investigated simultaneously gait and non-motor symptoms (executive functions, motor learning) in PD patients. Objective: To assess the impact of aerobic exercise training (AET) using a stationary bicycle on a set of gait parameters (walking speed, cadence, step length, step width, single and double support time, as well as variability of step length, step width and double support time) and executive functions (cognitive inhibition and flexibility) in sedentary PD patients and healthy controls. Methods: Two groups, 19 PD patients (Hoehn and Yahr ≤2) and 20 healthy adults, matched on age and sedentary level, followed a 3-month stationary bicycle AET regimen. Results: Aerobic capacity, as well as performance of motor learning and on cognitive inhibition, increased significantly in both groups after the training regimen, but only PD patients improved their walking speed and cadence (all p < 0.05; with no change in the step length). Moreover, in PD patients, training-related improvements in aerobic capacity correlated positively with improvements in walking speed (r = 0.461, p < 0.05). Conclusion: AET using stationary bicycle can independently improve gait and cognitive inhibition in sedentary PD patients. Given that increases in walking speed were obtained through increases in cadence, with no change in step length, our findings suggest that gait improvements are specific to the type of motor activity practiced during exercise (i.e., pedaling). In contrast, the improvements seen in cognitive inhibition were, most likely, not specific to the type of training and they could be due to indirect action mechanisms (i.e., improvement of cardiovascular capacity). These results are also relevant for the development of targeted AET interventions to improve functional autonomy in PD patients.

Should postactivation potentiation be the goal of your warm-up?

Athletes expect improved high-intensity performance following warm-up, and postactivation potentiation (PAP) is assumed to contribute to this improvement. However, the scientific evidence supporting this assumption is incomplete. PAP is known to result from prior muscle activation, and should enhance maximal effort contractions of very short duration. However, PAP dissipates over 4-6 min after the PAP-inducing contraction, so PAP should not contribute to enhanced performance more than 5 min after the warm-up.

The metabolically healthy but obese postmenopausal woman presents a favourable heart rate variability profile.

OBJECTIVE: The purpose of this study was to investigate the heart rate variability (HRV) profile in obese women displaying the metabolically healthy but obese (MHO) phenotype. DESIGN: We studied 47 obese, sedentary postmenopausal women. Subjects were classified as MHO or at risk based on insulin resistance as assessed with the homeostatic model assessment (HOMA) index. Subjects were divided into tertiles according to HOMA values. Subjects in the lower tertile were categorised as MHO while subjects in the upper 2 tertiles represented at risk subjects. Outcome measures were heart rate variability factors (RR intervals, SDNN, LF, HF, pNN50, RMSSD), body temperature, body composition (DEXA) and a lipid profile as well as glucose and insulin. RESULTS: MHO individuals had significantly lower resting heart rate, body temperature, lean body mass as well as fasting insulin and HOMA levels compared to at risk subjects (p < 0.05). In addition, RR intervals, SDNN and LF were significantly higher in MHO individuals (p < 0.05). Moreover, stepwise regression analysis showed that SDNN was an independent predictor of the variation in HOMA in our cohort. CONCLUSION: Results of the present study indicate that postmenopausal women displaying the MHO phenotype present a favourable HRV profile. Therefore, higher HRV could be associated, at least in part, in the protective profile of MHO individuals.

Metabolically healthy but obese individuals: relationship with hepatic enzymes.

The purpose of this study was to investigate the level of plasma hepatic enzymes in obese women displaying the metabolically healthy but obese (MHO) phenotype. We studied 104 obese, sedentary, postmenopausal women. Subjects were classified as MHO or at risk based on insulin sensitivity as assessed with the oral glucose tolerance test-derived Matsuda index. Subjects were divided into quartiles according to insulin sensitivity values. Subjects in the upper quartile were categorized as MHO, whereas subjects in the lower 3 quartiles represented at-risk subjects. Outcome measures were hepatic enzymes (aspartate aminotransferase [AST], alanine aminotransferase [ALT], alkaline phosphatase, and gamma-glutamyltransferase [GGT]], high-density lipoprotein cholesterol, triglycerides, triglycerides to high-density lipoprotein cholesterol ratio, apolipoprotein B, fatty liver index, body composition (dual-energy x-ray absorptiometry), and visceral adipose tissue (computed tomography). The MHO individuals had significantly lower concentrations of ALT, AST, and GGT as well as a lower fatty liver index compared with at-risk subjects (P < .05). In addition, lean body mass index and visceral adipose tissue were significantly lower in MHO individuals (P < .05). Moreover, stepwise regression analysis showed that ALT explained 17.9% of the variation in insulin sensitivity in our cohort, which accounted for the greatest source of unique variance. Results of the present study indicate that postmenopausal women displaying the MHO phenotype present favorable levels of ALT, AST, and GGT. Lower concentrations of hepatic enzymes, in particular, lower circulating ALT levels, in MHO individuals may reflect lower hepatic insulin resistance and lower liver fat content; and this could be involved, at least in part, in the protective profile of MHO individuals.

Resistance to Ca2+-induced opening of the permeability transition pore differs in mitochondria from glycolytic and oxidative muscles.

This study determined whether susceptibility to opening of the permeability transition pore (PTP) varies according to muscle phenotype represented by the slow oxidative soleus (Sol) and superficial white gastrocnemius (WG). Threshold for Ca2+-induced mitochondrial Ca2+ release following PTP opening was determined with a novel approach using permeabilized ghost myofibers. Threshold values for PTP opening were approximately threefold higher in fibers from WG compared with those from Sol (124+/-47 vs. 30.4+/-6.8 pmol Ca2+/mU citrate synthase). A similar phenomenon was also observed in isolated mitochondria (threshold: 121+/-60 vs. 40+/-10 nmol Ca2+/mg protein in WG and Sol), indicating that this was linked to differences in mitochondrial factors between the two muscles. The resistance of WG fibers to PTP opening was not related to the expression of putative protein modulators (cyclophilin D, adenylate nucleotide translocator-1, and voltage-dependent anion channels) or to difference in respiratory properties and occurred despite the fact that production of reactive oxygen species, which promote pore opening, was higher than in the Sol. However, endogenous matrix Ca2+ measured in mitochondria isolated under resting baseline conditions was approximately twofold lower in the WG than in the Sol (56+/-4 vs. 111+/-11 nmol/mg protein), which significantly accounted for the resistance of WG. Together, these results reveal fiber type differences in the sensitivity to Ca2+-induced PTP opening, which may constitute a physiological mechanism to adapt mitochondria to the differences in Ca2+ dynamics between fiber types.