Combined effect of AMPK/PPAR agonists and exercise training in mdx mice functional performance

The present investigation was undertaken to test whether exercise training (ET) associated with AMPK/PPAR agonists (EM) would improve skeletal muscle function in mdx mice. These drugs have the potential to improve oxidative metabolism. This is of particular interest because oxidative muscle fibers are less affected in the course of the disease than glycolitic counterparts. Therefore, a cohort of 34 male congenic C57Bl/10J mdx mice included in this study was randomly assigned into four groups: vehicle solution (V), EM [AICAR (AMPK agonist, 50 mg/Kg-1.day-1, ip) and GW 1516 (PPAR delta agonist, 2.5 mg/Kg-1.day-1, gavage)], ET (voluntary running on activity wheel) and EM+ET. Functional performance (grip meter and rotarod), aerobic capacity (running test), muscle histopathology, serum creatine kinase (CK), levels of ubiquitined proteins, oxidative metabolism protein expression (AMPK, PPAR, myoglobin and SCD) and intracellular calcium handling (DHPR, SERCA and NCX) protein expression were analyzed. Treatments started when the animals were two months old and were maintained for one month. A significant functional improvement (p<0.05) was observed in animals submitted to the combination of ET and EM. CK levels were decreased and the expression of proteins related to oxidative metabolism was increased in this group. There were no differences among the groups in the intracellular calcium handling protein expression. To our knowledge, this is the first study that tested the association of ET with EM in an experimental model of muscular dystrophy. Our results suggest that the association of ET and EM should be further tested as a potential therapeutic approach in muscular dystrophies.

Listening to music in the first, but not the last 1.5 km of a 5-km running trial alters pacing strategy and improves performance

We examined the effects of listening to music on attentional focus, rating of perceived exertion (RPE), pacing strategy and performance during a simulated 5-km running race. 15 participants performed 2 controlled trials to establish their best baseline time, followed by 2 counterbalanced experimental trials during which they listened to music during the first (M-start) or the last (M-finish) 1.5 km. The mean running velocity during the first 1.5 km was significantly higher in M-start than in the fastest control condition (p < 0.05), but there was no difference in velocity between conditions during the last 1.5 km (p > 0.05). The faster first 1.5 m in M-start was accompanied by a reduction in associative thoughts compared with the fastest control condition. There were no significant differences in RPE between conditions (p > 0.05). These results suggest that listening to music at the beginning of a trial may draw the attentional focus away from internal sensations of fatigue to thoughts about the external environment. However, along with the reduction in associative thoughts and the increase in running velocity while listening to music, the RPE increased linearly and similarly under all conditions, suggesting that the change in velocity throughout the race may be to maintain the same rate of RPE increase.

AEROBIC OR RESISTANCE EXERCISE IMPROVES PERFORMANCE IN ACTIVITIES OF DAILY LIVING IN ELDERLY WOMEN

The purpose of this randomized non-controlled study was to determine the effect of an aerobic or resistance exercise protocol on performance of activities of daily living in elderly women. The sample was constituted of 41 apparently healthy elderly women aged 60 to 85 years (x: 65.1 +/- 7.9 years) randomly assigned in resistance exercise (n: 22) or aerobic groups (n: 19). The resistance exercise protocol consisted of three sets of eight to 12 repetitions at 60% of one repetition maximum test for the leg press 45 degrees. The aerobic exercise protocol consisted in cycling in a cycle ergometer during 40 minutes at 60% of reserve heart rate. Both protocols were performed three times per week during five weeks. Activities of daily living were estimated by velocity to stand from sitting to standing position (VSitting), velocity to move from supine to standing position (VSupine), velocity to climb stairs (VCS) and velocity to wear sneakers (VWS). Volunteers of aerobic exercise protocol improved significantly the time to perform VWS (19.1%), while the volunteers of resistance exercise protocol improved the capacity to perform VCS (4.3%) and VSupine (8.9%). These results let us conclude that aerobic as well as resistance exercise protocols induced positive effect on activities of daily living, suggesting that both protocols must be associated for an adequate exercise program to improve the functional capacity of elderly people.

Do muscle strengthening exercises improve performance in the 6-minute walk test in postmenopausal women?

Background: Walking speed seems to be related to aerobic capacity, lower limb strength, and functional mobility, however it is not clear whether there is a direct relationship between improvement in muscle strength and gait performance in early postmenopausal women. Objective: To evaluate the effect of muscle strengthening exercises on the performance of the 6-minute walk test in women within 5 years of menopause. Methods: The women were randomized into control group (n=31), which performed no exercise, and exercise group (n=27), which performed muscle strengthening exercises. The exercises were performed twice a week for 3 months. The exercise protocol consisted of warm-up, stretching, and strengthening of the quadriceps, hamstring, calf, tibialis anterior, gluteus maximus, and abdominal muscles, followed by relaxation. Muscular strength training started with 60% of 1MR (2 series of 10-15 repetitions), reaching 85% until the end of the 3-month period (4 series of 6 repetitions each). Results: The between-group comparisons pre- and post-intervention did not show any difference in distance walked, heart rate or blood pressure (p>0.05), but showed differences in muscle strength post-intervention, with the exercise group showing greater strength (p<0.05). In the within-group comparison, there were differences in final heart rate and quadriceps and hamstring strength pre- and post-intervention in the exercise group (p<0.05). Conclusion: The results suggest that muscle strengthening of the lower limbs did not improve performance in the 6-minute walk test in this population of postmenopausal women. Trial registration ACTRN12609001053213.

Lack of beta(2)-AR improves exercise capacity and skeletal muscle oxidative phenotype in mice

beta(2)-adrenergic receptor (beta(2)-AR) agonists have been used as ergogenics by athletes involved in training for strength and power in order to increase the muscle mass. Even though anabolic effects of beta(2)-AR activation are highly recognized, less is known about the impact of beta(2)-AR in endurance capacity. We presently used mice lacking beta(2)-AR [beta(2)-knockout (beta(2) KO)] to investigate the role of beta(2)-AR on exercise capacity and skeletal muscle metabolism and phenotype. beta(2) KO mice and their wild-type controls (WT) were studied. Exercise tolerance, skeletal muscle fiber typing, capillary-to-fiber ratio, citrate synthase activity and glycogen content were evaluated. When compared with WT, beta 2KO mice displayed increased exercise capacity (61%) associated with higher percentage of oxidative fibers (21% and 129% of increase in soleus and plantaris muscles, respectively) and capillarity (31% and 20% of increase in soleus and plantaris muscles, respectively). In addition, beta 2KO mice presented increased skeletal muscle citrate synthase activity (10%) and succinate dehydrogenase staining. Likewise, glycogen content (53%) and periodic acid-Schiff staining (glycogen staining) were also increased in beta 2KO skeletal muscle. Altogether, these data provide evidence that disruption of beta(2)AR improves oxidative metabolism in skeletal muscle of beta 2KO mice and this is associated with increased exercise capacity.

Overexpression of inducible 70-kDa heat shock protein in mouse improves structural and functional recovery of skeletal muscles from atrophy

Heat shock proteins play a key regulatory role in cellular defense. To investigate the role of the inducible 70-kDa heat shock protein (HSP70) in skeletal muscle atrophy and subsequent recovery, soleus (SOL) and extensor digitorum longus (EDL) muscles from overexpressing HSP70 transgenic mice were immobilized for 7 days and subsequently released from immobilization and evaluated after 7 days. Histological analysis showed that there was a decrease in cross-sectional area of type II myofiber from EDL and types I and II myofiber from SOL muscles at 7-day immobilization in both wild-type and HSP70 mice. At 7-day recovery, EDL and SOL myofibers from HSP70 mice, but not from wild-type mice, recovered their size. Muscle tetanic contraction decreased only in SOL muscles from wild-type mice at both 7-day immobilization and 7-day recovery; however, it was unaltered in the respective groups from HSP70 mice. Although no effect in a fatigue protocol was observed among groups, we noticed a better contractile performance of EDL muscles from overexpressing HSP70 groups as compared to their matched wild-type groups. The number of NCAM positive-satellite cells reduced after immobilization and recovery in both EDL and SOL muscles from wild-type mice, but it was unchanged in the muscles from HSP70 mice. These results suggest that HSP70 improves structural and functional recovery of skeletal muscle after disuse atrophy, and this effect might be associated with preservation of satellite cell amount.

Anthropometric, physiological, performance, and nutritional profile of the Brazil National Canoe Polo Team

The purpose of this study was to determine the physiological, anthropometric, performance, and nutritional characteristics of the Brazil Canoe Polo National Team. Ten male canoe polo athletes (age 26.7 +/- 4.1 years) performed a battery of tests including assessments of anthropometric parameters, upper-body anaerobic power (Wingate), muscular strength, aerobic power, and nutritional profile. In addition, we characterized heart rate and plasma lactate responses and the temporal pattern of the effort/recovery during a simulated canoe polo match. The main results are as follows: body fat, 12.3 +/- 4.0%; upper-body peak and mean power, 6.8 +/- 0.5 and 4.7 +/- 0.4 W . kg(-1), respectively; 1-RM bench press, 99.1 +/- 11.7 kg; peak oxygen uptake, 44.3 +/- 5.8 mL . kg(-1) . min(-1); total energy intake, 42.8 +/- 8.6 kcal . kg(-1); protein, carbohydrate, and fat intakes, 1.9 +/- 0.1, 5.0 +/- 1.5, and 1.7 +/- 0.4 g . kg(-1), respectively; mean heart rate, 146 +/- 11 beats . min(-1); plasma lactate, 5.7 +/- 3.8 mmol . L-1 at half-time and 4.6 +/- 2.2 mmol . L-1 at the end of the match; effort time (relative to total match time), 93.1 +/- 3.0%; number of sprints, 9.6 +/- 4.4. The results of this study will assist coaches, trainers, and nutritionists in developing more adequate training programmes and dietary interventions for canoe polo athletes.

Exercise training improves neurovascular control and functional capacity in heart failure patients regardless of age

Background: Exercise training is a non-pharmacological strategy for treatment of heart failure. Exercise training improves functional capacity and quality of life in patients. Moreover, exercise training reduces muscle sympathetic nerve activity (MSNA) and peripheral vasoconstriction. However, most of these studies have been conducted in middle-aged patients. Thus, the effects of exercise training in older patients are much less understood. The present study was undertaken to investigate whether exercise training improves functional capacity, muscular sympathetic activation and muscular blood flow in older heart failure patients, as it does in middle-aged heart failure patients. Design: Fifty-two consecutive outpatients with heart failure from the database of the Unit of Cardiovascular Rehabilitation and Physiology Exercise were divided by age (middle-aged, defined as 45-59 years, and older, defined as 60-75 years) and exercise status (trained and untrained). Methods: MSNA was recorded directly from the peroneal nerve using the microneurography technique. Forearm Blood Flow (FBF) was measured by venous occlusion plethysmography. Functional capacity was evaluated by cardiopulmonary exercise test. Results: Exercise training significantly and similarly increased FBF and peak VO2 in middle-aged and older heart failure patients. In addition, exercise training significantly and similarly reduced MSNA and forearm vascular resistance in these patients. No significant changes were found in untrained patients. Conclusion: Exercise training improves neurovascular control and functional capacity in heart failure patients regardless of age.

Motor function measure scale, steroid therapy and patients with Duchenne muscular dystrophy

Objective: To assess the evolution of motor function in patients with Duchenne muscular dystrophy (DMD) treated with steroids (prednisolone or deflazacort) through the Motor Function Measure (MFM), which evaluates three dimensions of motor performance (D1, D2, D3). Methods: Thirty-three patients with DMD (22 ambulant, 6 non-ambulant and 5 who lost the capacity to walk during the period of the study) were assessed using the MFM scale six times over a period of 18 months. Results: All the motor functions remained stable for 14 months in all patients, except D1 for those who lost their walking ability. In ambulant patients, D2 (axial and proximal motor capacities) motor functions improved during six months; an improvement in D3 (distal motor capacity) was noted during the total follow-up. D1 (standing posture and transfers) and total score were useful to predict the loss of the ability to walk. Conclusions: The use of the MFM in DMD patients confirms the benefits of the steroid treatment for slowing the progression of the disease.

Organic milk improves Bifidobacterium lactis counts and bioactive fatty acids contents in fermented milk

In functional dairy products, polyunsaturated fatty acids such as, conjugated linoleic acid (CLA) and alpha-linolenic acid (ALA) have been highlighted for their benefits related to prevention of some chronic diseases. In order to study the effect of type of milk (conventional vs. organic, characterized by a specific fatty acid composition), Bifidobacterium animalis subsp. lactis (BB12, B94, BL04 and HN019) counts, acidification activity and chemical composition (pH, lactose, lactic acid contents and fatty acids profile) were investigated before fermentation and after 24 h of products stored at 4 degrees C. Organic and conventional milk influenced acidification performance and bacteria counts, which was strain-dependent. Higher counts of BB12 were observed in organic milk, whereas superior counts of BL04 were found in conventional milk. Organic fermented milk showed lower levels in saturated fatty acids (FA) and higher in monounsaturated FA contents. Similarly, among bioactive FA, organic fermented milks have higher amounts of trans vaccenic acid (TVA-C18:1t), conjugated linoleic acid (CLA) and slightly higher contents of alpha-linoleic acid (ALA). (C) 2012 Elsevier Ltd. All rights reserved.

The effect of acute magnesium loading on the maximal exercise performance of stable chronic obstructive pulmonary disease patients

OBJECTIVE: The potential influence of magnesium on exercise performance is a subject of increasing interest. Magnesium has been shown to have bronchodilatatory properties in asthma and chronic obstructive pulmonary disease patients. The aim of this study was to investigate the effects of acute magnesium IV loading on the aerobic exercise performance of stable chronic obstructive pulmonary disease patients. METHODS: Twenty male chronic obstructive pulmonary disease patients (66.2 +/- 8.3 years old, FEV1: 49.3 +/- 19.8%) received an IV infusion of 2 g of either magnesium sulfate or saline on two randomly assigned occasions approximately two days apart. Spirometry was performed both before and 45 minutes after the infusions. A symptom-limited incremental maximal cardiopulmonary test was performed on a cycle ergometer at approximately 100 minutes after the end of the infusion. ClinicalTrials.gov: NCT00500864 RESULTS: Magnesium infusion was associated with significant reductions in the functional residual capacity (-0.41 l) and residual volume (-0.47 l), the mean arterial blood pressure (-5.6 mmHg) and the cardiac double product (734.8 mmHg.bpm) at rest. Magnesium treatment led to significant increases in the maximal load reached (+8 w) and the respiratory exchange ratio (0.06) at peak exercise. The subgroup of patients who showed increases in the work load equal to or greater than 5 w also exhibited significantly greater improvements in inspiratory capacity (0.29 l). CONCLUSIONS: The acute IV loading of magnesium promotes a reduction in static lung hyperinflation and improves the exercise performance in stable chronic obstructive pulmonary disease patients. Improvements in respiratory mechanics appear to be responsible for the latter finding.

Analysis of temperature variation influence on the analog performance of 45 degrees rotated triple-gate nMuGFETs

This work presents the analog performance of n-type triple-gate MuGFETs with high-k dielectrics and TiN gate material fabricated in 45 degrees rotated SOI substrates comparing their performance with standard MuGFETs fabricated without substrate rotation. Different fin widths are studied for temperatures ranging from 250 K up to 400 K. The results of transconductance, output conductance, transconductance over drain current ratio, intrinsic voltage gain and unit-gain frequency are studied. It is observed that the substrate rotation improves the carrier mobility of narrow MuGFETs at any temperature because of the changing in the conduction plane at the sidewalls from (1 1 0) to (1 0 0). For lower temperatures, the improvement of the carrier mobility of rotated MuGFETs is more noticeable as well as the rate of mobility improvement with the temperature decrease is larger. The output conductance is weakly affected by the substrate rotation. Although this improvement in the transconductance of rotated MuGFETs is negligibly transferred to the intrinsic voltage gain, the unity-gain frequency of rotated device is improved due to the larger carrier mobility in the entire range of temperatures studied. (C) 2011 Elsevier Ltd. All rights reserved.

Chronic Stress Improves the Myocardial Function without Altering L-type Ca+2 Channel Activity in Rats

Background: Chronic stress is associated with cardiac remodeling; however the mechanisms have yet to be clarified. Objective: The purpose of this study was test the hypothesis that chronic stress promotes cardiac dysfunction associated to L-type calcium Ca2+ channel activity depression. Methods: Thirty-day-old male Wistar rats (70 - 100 g) were distributed into two groups: control (C) and chronic stress (St). The stress was consistently maintained at immobilization during 15 weeks, 5 times per week, 1h per day. The cardiac function was evaluated by left ventricular performance through echocardiography and by ventricular isolated papillary muscle. The myocardial papillary muscle activity was assessed at baseline conditions and with inotropic maneuvers such as: post-rest contraction and increases in extracellular Ca2+ concentration, in presence or absence of specific blockers L-type calcium channels. Results: The stress was characterized for adrenal glands hypertrophy, increase of systemic corticosterone level and arterial hypertension. The chronic stress provided left ventricular hypertrophy. The left ventricular and baseline myocardial function did not change with chronic stress. However, it improved the response of the papillary muscle in relation to positive inotropic stimulation. This function improvement was not associated with the L-type Ca2+ channel. Conclusion: Chronic stress produced cardiac hypertrophy; however, in the study of papillary muscle, the positive inotropic maneuvers potentiated cardiac function in stressed rats, without involvement of L-type Ca2+ channel. Thus, the responsible mechanisms remain unclear with respect to Ca2+ influx alterations. (Arq Bras Cardiol 2012;99(4):907-914)

Exercício aeróbico ou com pesos melhora o desempenho nas atividades da vida diária de mulheres idosas

Este estudo aleatorizado não controlado teve como objetivo determinar o efeito de um protocolo de exercício com pesos ou aeróbico no desempenho das atividades da vida diária em mulheres idosas. Para tanto, a amostra foi constituída por 41 mulheres idosas aparentemente saudáveis na faixa etária de 60 a 85 anos de idade (x: 65,1 ± 7,9 anos) divididas aleatoriamente em grupo exercício com pesos (n: 22) ou aeróbico (n: 19). O grupo exercício com pesos consistiu na execução de três séries de oito a 12 repetições a 60% de uma repetição máxima no exercício leg press 45º. O grupo exercício aeróbico consistiu em pedalar em cicloergômetro durante 40 minutos a 60% da frequência cardíaca de reserva. Os dois protocolos foram realizados três vezes por semana durante cinco semanas. As atividades da vida diária selecionadas foram velocidade para se levantar de uma posição sentada (VLPS), velocidade para se levantar de uma posição deitada (VLPD), velocidade para subir escada (VSE) e velocidade para calçar e amarrar o tênis (VCAT). O grupo exercício aeróbico melhorou significativamente o desempenho em VCAT (19,1%), enquanto o exercício com pesos incrementou significativamente o desempenho em VSE (4,3%) e VLPS (8,9%). Os resultados deste estudo permitem concluir que tanto o exercício com pesos como o aeróbico induziram efeito positivo nas atividades da vida diária, sugerindo que ambas as modalidades de exercício devem ser associadas a um programa adequado de exercícios para a melhora da capacidade funcional de pessoas idosas.

Suplementação oral de L-carnitina associada ao treinamento físico e muscular respiratório na doença pulmonar obstrutiva crônica: estudo preliminar

Avaliar os efeitos da suplementação oral de L-carnitina associada ao treinamento físico e muscular respiratório na doença pulmonar obstrutiva crônica (DPOC). Participaram 14 voluntários com idade de 65±10,4 anos e diagnóstico clínico de DPOC moderado, classificados de acordo com a espirometria prévia. Os voluntários foram divididos em grupo treino esteira (GTE) e grupo treino muscular respiratório (GTMR). Realizaram o teste de caminhada de seis minutos (TC6'), teste de caminhada com carga progressiva (TCP), avaliação nutricional do índice de massa corpórea (IMC), dose diária recomendada de L-carnitina, pressões inspiratórias (PImáx) e expiratórias máximas (PEmáx). Fizeram 30 min de caminhada em esteira, 3 vezes/semana por 10 semanas, e o GTMR realizou, ainda, 10 min de treinamento muscular inspiratório (Threshold® IMT) e 10 min de treinamento muscular expiratório (Threshold® PEP) à 50% da PImáx e PEmáx ajustados semanalmente. Após 10 semanas, foram reavaliados. No TC6' pré e pós-programa de treinamento físico, as variáveis alteradas foram: distância percorrida (DP), frequência cardíaca (FC) final, pressão arterial sistólica (PAS) final, pressão arterial diastólica (PAD) final e Borg final no GTMR, no GTE as variáveis alteradas foram FC repouso, FC final, PAS final, Borg repouso e DP. Comparando os grupos no TC6, o GTE apresentou FC final, PAD final e Borg final maiores do que o GTMR na reavaliação; já no TCP, a FC final, PAS final, Borg final foram maiores no GTE, e DP foi maior no GTMR. Na avaliação respiratória, a PEmáx foi maior no GTMR na reavaliação. O treino aeróbio e suplementação de L-carnitina na DPOC otimizou a performance, a capacidade física e a tolerância ao esforço.