Goncalo V. Mendonca

Walking economy of adults with down syndrome

This study intended to investigate walking economy (WE) in response to different treadmill speeds and grades in adults with Down syndrome (DS) and in non-disabled controls. Eighteen participants (14 males; 4 females) with DS (33.6+/-7.6 years) and 16 non-disabled (12 males, 4 females) controls (33.3+/-8.0 years) performed submaximal (2.5 km . h (-1) and 4 km . h (-1) at 0% grade; 4 km . h (-1) at 2.5% and 5% grade, for 5 min each) and maximal treadmill tests with metabolic and heart rate measurements. Oxygen uptake (VO(2)) was not different between groups at rest or during the slowest treadmill speed. However, at faster speeds and increased grades, adults with DS presented lower WE than controls (p<0.0001). Subsequent analyses revealed that, despite showing higher delta VO(2) response to the selected speed increments (p<0.0001), individuals with DS produced similar VO(2) increase as controls to grade variations. Therefore, adults with DS exhibit lower WE than non-disabled controls at a speed faster than their preferred walking speed. Additionally, in comparison to controls, individuals with DS show a greater change in energy expenditure with a change in walking speed. In conclusion, lower WE in individuals with DS is mainly related to their inability to adapt efficiently to positive variations in walking speed.

Medidas de composição corporal em adultos portadores de Síndrome de Down

The purpose of the present study was to determine the general level of agreement between the body mass index (BMI), adiposity estimates, waist circumference (WC) assessments, and percentage body fat (BF) measurements by bioelectrical-impedance spectroscopy (BIS) analyses in 20 adult males with Down syndrome (33.5 ± 6.5 years old). BIS was selected as a criterion measure after comparing its estimates with those of dual-energy X-ray absorptiometry (DXA) performed on 10 participants. There were no significant differences between %BF reported by BIS and DXA (p = 0.339) and both measures were moderately correlated (r = 0.71, p = 0.0019). Additionally, %BF estimated by BMI calculations and that obtained by BIS assessments were not significantly different (22.7 ± 4.9% e 23.3 ± 4.6%; t[19] = 0.819, p = 0.219, respectively). Both the BMI and WC were significantly correlated with %BF determined by BIS (p < 0.0001). Furthermore, BMI was significantly associated with %BF measured by BIS (χ2 = 9.7; p = 0.002). As for BMI, WC measurements were significantly associated with %BF obtained by BIS (χ2 = 8.9; p = 0.003). Thus, our main finding is that, both the BMI and WC provide good estimates of body fatness levels in adult males with Down syndrome.

Between-day variability of net and gross oxygen uptake during graded treadmill walking: effects of different walking intensities on the reliability of locomotion economy

There have been few studies of clinical relevance conducted on the reliability of walking economy. This study was designed to determine if walking economy reproducibility increases as a function of walking intensity, and if there is any advantage in expressing walking economy as net oxygen uptake (VO2) rather than gross VO2 for reproducibility purposes. Sixteen participants (9 males, 7 females; mean age, 22.3 +/- 4.3 years) performed resting, submaximal, and maximal protocols on 2 different days, under identical circumstances, within a 7 day period. The submaximal protocol consisted of five 5 min walks (4 km.h-1) at treadmill grades of 0%, 2.5%, 5.0%, 7.5%, and 10%. Findings indicate that increments of 2.5% in treadmill grade effectively increased gross and net VO2 during walks. The reliability of net and gross measures increased as a function of walking relative intensity, reporting intraclass correlation coefficients ranging from 0.89-0.94 and 0.87-0.91, respectively, and mean coefficients of variation (CV) from 7.3%-3.6% and 8.8%-4.4%, respectively. There were no significant differences between the CV for gross and for net VO2 across the spectrum of walking relative intensities. In conclusion, there is no advantage of expressing walking economy as net VO2 instead of gross VO2 for reproducibility purposes, and a single treadmill testing session at a constant speed of 4 km.h-1 is reliable for estimating group and individual walking economy, particularly at higher percent grades.

Metabolic cost of locomotion during treadmill walking with blood flow restriction.

We explored whether interval walking with blood flow restriction (BFR) increases net metabolic cost of locomotion in healthy young men at their optimal walking speed. We also determined whether decreased walking economy resulting from BFR might be accompanied by an increase in ventilation relative to VO2 and VCO2. Finally, we examined possible relationships between the changes in ratings of perceived exertion (RPE) and those obtained in minute ventilation (VE) during walking with BFR. Eighteen healthy men (age: 22·5 ± 3·4 years) performed graded treadmill exercise to assess VO2max. In a randomized fashion, participants also performed five bouts of 3‐min treadmill exercise with and without BFR at their optimal walking speed. Walking with BFR elicited an overall increase in net VO2 (10·4%) compared with that seen in the non‐BFR condition (P<0·05). The participants also demonstrated greater VE and VE/VO2 values while walking with BFR (P<0·05). Conversely, VE/VCO2 was similar between conditions at each walking bout. We found no significant correlation between the changes in VE and RPE induced by walking with BFR (r = 0·38, P>0·05). Our results indicate that (i) BFR decreases net walking economy in healthy young men, even at their optimal walking speed; (ii) heightened ventilatory drive may explain a small proportion of BFR effects on walking economy; and (iii) the ventilatory responses to BFR walking may be largely independent of changes in perceived exertion and are likely matched to the flux of CO2 between muscles and respiratory centres.

Impact of Exercise Training on Physiological Measures of Physical Fitness in the Elderly

BACKGROUND Older persons are the fastest growing segment of the population living in the Western hemisphere. Longevity comes at a price, including a higher rate of morbidity, functional and mental disability and the eventual loss of independence. Physical inactivity further aggravates the decline in physiological function along the aging process. Therefore, the promotion of regular exercise may be seen as one of the main non-pharmacological approaches that should be recommended to older adults. METHODS We performed a comprehensive review on the interaction between exercise training and improved physical fitness in the elderly. Specifically, 175 papers describing the overall benefits of exercise training on the cardiovascular, neuromuscular and brain function of older adults were included. The effectiveness of training for improving quality of life at an older age was also reviewed. RESULTS Exercise training can partially reverse the age-related physiological decline and enhance work capacity in the elderly. Numerous studies have shown that maintaining a minimum quantity and quality of physical exercise decreases the risk of cardiovascular mortality, sarcopenia, prevents the onset of osteopenia and even exerts a prophylactic role against neurodegeneration. The systemic physiologic effects are profound and may be directly linked to a favorable feedforward cycle whereby improved physiologic function begets improved physical function and so on. CONCLUSION We conclude that structured training programs should be designed to improve the physiological function in this population. Finally, the benefits of exercise training vary as a function of training volume and this relationship is independent of age and sex.

Effects of Walking with Blood Flow Restriction on Excess Post-exercise Oxygen Consumption

This study determined the influence of walking with blood flow restriction (BFR) on the excess post-exercise oxygen consumption (EPOC) of healthy young men. 17 healthy young men (22.1±2.9 years) performed graded treadmill exercise to assess VO2peak. In a randomized fashion, each participant performed 5 sets of 3-min treadmill exercise at their optimal walking speed with 1-min interval either with or without BFR. Participants were then seated in a chair and remained there for 30 min of recovery. Expired gases were continuously monitored during exercise and recovery. BFR increased the O2 cost of walking as well as its relative intensity and cumulative O2 deficit (p<0.05). The EPOC magnitude after walking with BFR was greater than in the non-BFR condition (p<0.05). No differences between conditions were seen for the duration of EPOC. The EPOC magnitude was no longer different between conditions after controlling for the differences in relative intensity and in the cumulative O2 deficit (p>0.05). These data indicate that walking with BFR increases the magnitude of EPOC. Moreover, they also demonstrate that such increment in EPOC is likely explained by the effects of BFR on walking relative intensity and cumulative O2 deficit.

The influence of water ingestion on postexercise hypotension and standing haemodynamics

In young healthy adults, postexercise hypotension (PEH) occurs after a single bout of dynamic exercise due to peripheral vasodilation. Gravitational stress may further aggravate the magnitude of PEH, thus predisposing to orthostatic intolerance. As water drinking activates sympathetic vasoconstriction, it might offset PEH via enhanced α‐adrenergic vascular responsiveness. We hypothesized that water ingestion before exercise would decrease the magnitude of PEH and improve the haemodynamic reaction to active standing postmaximal exercise. In a randomized fashion, 17 healthy adults (nine men; eight women, 21·2 ± 1·6 years) ingested 50 and 500 ml of water before completing resting, cycle ergometer and recovery protocols on two separate days. After exercise, measurements [arterial blood pressure (BP), heart rate and spectral heart rate variability (HRV)] were taken in the seated position followed by 5 min of active standing. Compared to that seen post‐50 ml of water, the 500 ml volume elicited an overall increase in BP (P < 0·05). Nevertheless, the magnitude of PEH was not different after either volume of water. There was an overall bradycardic effect of water, and this was accompanied by increased high‐frequency power (P < 0·05). Finally, no BP, heart rate or HRV differences were found between conditions in response to active standing. These data suggest that, despite being well preserved after maximal exercise, the water pressor response does not affect the magnitude of PEH. They also indicate that drinking 500 ml of water does not impact the BP, heart rate or HRV response to 5 min of active standing during recovery postmaximal exercise.

Sexual dimorphism in the osmopressor response following water ingestion

Compared with men, women exhibit a greater magnitude of increase in resting blood pressure after drinking a single water bolus of 500 ml. Accordingly, our study provides direct evidence of sexual dimorphism in the haemodynamic response to water intake.

Prediction of energy expenditure during walking in adults with down syndrome

BACKGROUND When developing walking programmes for improving health in adults with Down syndrome (DS), physical activity professionals are in need of an equation for predicting energy expenditure. We therefore developed and cross-validated an equation for predicting the rate of oxygen uptake (VO2 ; an index of energy expenditure) for adults with and without DS. METHOD A total of 469 VO2 observations during walking across different speeds were available from 54 adults with DS and 61 adults without DS. RESULTS Significant predictors of VO2 were speed, speed square, group and group-by-speed interaction. Separate models for each group showed that speed and its square significantly predicted VO2 . Absolute per cent error was small and did not differ between groups. CONCLUSION Adults with DS have different VO2 response to walking speed from persons without DS. VO2 is predicted from speed with acceptable accuracy for persons with DS.

A systematic review on the effects of occlusal splint therapy on muscle strength

ABSTRACT Objective: The aim of this study was to conduct a systematic review on the effectiveness of occlusal splints for improving muscle strength. Occlusal splints are oral appliances that cause joint stabilization. Methods: A mix of medical and sports science terms was used to perform the search on several databases (Web of Science, Science Direct, SPORT Discus, PubMed, and Springer). Results: Twelve studies were reviewed, and their analysis indicates a trend pointing toward a limited interaction between the use of occlusal splints and improved muscle strength. Discussion: The extent of occlusal splints’ impact on muscle strength is presently unknown. At this stage, there is no general agreement as to whether occlusal splints can be used as ergogenic aids. The number of studies on this specific topic and their different experimental designs precludes drawing more definite conclusions. Further research is warranted to elucidate possible changes resulting from occlusal splints during exercise.