Álvaro Sosa Machado

Efeitos da manipulação da sensibilidade plantar sobre o controle da postura ereta em adultos jovens e idosos

INTRODUCTION Subjects with sensorial losses present balance deficits. Although such condition is often observed among elderly, there is discussion concerning the dependence on sensorial information for body sway control in the elderly without sensorial losses. PURPOSE We investigated the effects of foot sensitivity manipulation on postural control during upright standing in young adults and independent elderly (n=19/group). METHODS Plantar sensitivity was evaluated by esthesiometry, and speed of center of pressure shift data during upright posture were evaluated for each foot using a baropodometer while the subjects were standing with eyes open or closed. The young adult group was evaluated for pressure center in normal conditions and after plantar sensitivity disturbance, by immersing their feet in water and ice. RESULTS Young adults did not show alterations in their center of pressure after sensorial perturbation and presented, even under sensorial perturbation, better postural control than elderly subjects. The elderly showed lower foot sensitivity and greater center of pressure oscillation than young adults. CONCLUSION Elderly subjects seem to rely more on foot sensitivity for control of body sway than young adults. In the elderly, a clinical intervention to improve foot sensitivity may help in upright posture maintenance.

Effects of plantar foot sensitivity manipulation on postural control of young adult and elderly

INTRODUCTION Subjects with sensorial losses present balance deficits. Although such condition is often observed among elderly, there is discussion concerning the dependence on sensorial information for body sway control in the elderly without sensorial losses. PURPOSE We investigated the effects of foot sensitivity manipulation on postural control during upright standing in young adults and independent elderly (n=19/group). METHODS Plantar sensitivity was evaluated by esthesiometry, and speed of center of pressure shift data during upright posture were evaluated for each foot using a baropodometer while the subjects were standing with eyes open or closed. The young adult group was evaluated for center of pressure in normal conditions and after plantar sensitivity disturbance, by immersing their feet in water and ice. RESULTS Young adults did not show alterations in their center of pressure after sensorial perturbation and presented, even under sensorial perturbation, better postural control than elderly subjects. The elderly showed lower foot sensitivity and greater center of pressure oscillation than young adults. CONCLUSION Elderly subjects seem to rely more on foot sensitivity for control of body sway than young adults. In the elderly, a clinical intervention to improve foot sensitivity may help in upright posture maintenance.

Effect of green tea extract supplementation on exercise-induced delayed onset muscle soreness and muscular damage

Previous studies addressed the antioxidant and anti-inflammatory role of compounds from green tea in different human tissues. Positive antioxidant and anti-inflammatory effects were described for brain tissues. Whether similar effects are observed in the skeletal muscle, green tea supplementation could be a strategy to reduce delayed onset muscle soreness resultant of exercise. Here we determine the effect of green tea extract supplementation on exercise-induced muscle soreness, muscle damage and oxidative stress. We performed a randomized triple blind placebo control study. Twenty non-trained men performed sessions of exercise to induce delayed onset muscle soreness in the triceps sural muscle group before and after 15 days of supplementation (500 mg/day) with green tea extract (n = 10) or a placebo (n = 10). Muscle soreness was evaluated using a visual scale. Blood samples were taken at different moments to determine serum blood markers of muscle damage, oxidative stress and antioxidant status. We found that exercise induced delayed onset muscle soreness. Supplementation reduced muscle damage but muscle soreness did not change. Plasma oxidative damage marker and antioxidant status did not show an effect of supplementation. As a conclusion, green tea extract supplementation did not reduce the sensation of delayed onset muscle soreness but reduces the marker of muscle damage after exercise. It suggests the green tea extract supplementation has positive effects on muscle recovery after strenuous exercise.

Artigo originalInfluência da velocidade da marcha sobre a pressão plantar em sujeitos com osteoartrite unilateral de joelhoInfluence of gait speed on plantar pressure in subjects with unilateral knee osteoarthritis

OBJECTIVE Changing gait speed is a common strategy to manipulate exercise intensity during physical exercise, but may elicit higher impact forces and consequent joint loading. Here we analyzed the effects of increasing walking velocity on plantar pressure and asymmetries in elderly with knee osteoarthritis (OA). Our hypothesis was that the contralateral limb could receive higher loading compared to the OA limb in the different walking speeds tested. METHODS Twelve elderly with unilateral knee OA walked at different self-selected speeds along a 10 m pass way stepping on an instrumented mat for measurement of plantar pressure at preferred, slow and fast gait speeds. Five steps were recorded for each speed. Plantar pressure data were compared between the speeds and legs. RESULTS speeds were significantly different between them (p<0.05). Mean and peak plantar pressure increased when speed changed from slow to fast (p<0.05). Velocity of the center of pressure increased and the single stance time decreased when walk speed was increased (p<0.05). Any asymmetries were observed. CONCLUSION Increasing gait speed from slow to fast in subjects with unilateral knee OA significantly affected variables of plantar pressure, but asymmetries between committed and contralateral leg were not detected.

Influence of gait speed on plantar pressure in subjects with unilateral knee osteoarthritis

OBJECTIVE Changing gait speed is a common strategy to manipulate exercise intensity during physical exercise, but may elicit higher impact forces and consequent joint loading. Here we analyzed the effects of increasing walking velocity on plantar pressure and asymmetries in elderly with knee osteoarthritis (OA). Our hypothesis was that the contralateral limb could receive higher loading compared to the OA limb in the different walking speeds tested. METHODS Twelve elderly with unilateral knee OA walked at different self-selected speeds along a 10 m pass way stepping on an instrumented mat for measurement of plantar pressure at preferred, slow and fast gait speeds. Five steps were recorded for each speed. Plantar pressure data were compared between the speeds and legs. RESULTS speeds were significantly different between them (p<0.05). Mean and peak plantar pressure increased when speed changed from slow to fast (p<0.05). Velocity of the center of pressure increased and the single stance time decreased when walk speed was increased (p<0.05). Any asymmetries were observed. CONCLUSION Increasing gait speed from slow to fast in subjects with unilateral knee OA significantly affected variables of plantar pressure, but asymmetries between committed and contralateral leg were not detected.

Can exercise induced muscle damage be related to changes in skin temperature

OBJECTIVE Measurement of skin temperature using infrared thermography has become popular in sports, and has been proposed as an indicator of exercise-induced muscle damage after exercise. However, the relationship between skin temperature and exercise-induced muscle damage is still unclear. Here we set out to investigate the relationship between skin temperature and exercise-induced muscle damage. APPROACH Twenty untrained participants completed a protocol of exercise for calf muscles. Before and after exercise blood samples were collected to determine creatine kinase and acetylcholinesterase activity. Thermal images were recorded from the exercised muscles to determine skin temperature. Delayed onset muscle soreness was quantified. Correlations between skin temperature and exercise-induced muscle damage were analyzed considering thermal data, creatine kinase and acetylcholinesterase activity at different time moments. MAIN RESULTS We found delayed onset muscle soreness and an increased creatine kinase activity 48 h after exercise (P  <  0.01). Skin temperature parameters (average, maximal, amplitude and difference pre- and post-exercise, immediately after and 48 h after) did not correlate with the creatine kinase responses (P  >  0.05). Acetylcholinesterase activity remained stable (P  =  0.59). SIGNIFICANCE We recommend caution when considering changes in skin temperature as dependent on the level of localized and symmetric muscle damage considering calf muscles in untrained participants.

Green tea extract preserves neuromuscular activation and muscle damage markers in athletes under cumulative fatigue

A main implication of cumulative fatigue is the muscle damage that impairs neuromuscular function and training adaptations. These negative effects may limit performance when athletes exercise in consecutive days. In this regard, antioxidant supplementation has gain popularity among athletes. Green tea supplementation has been advocated as a strategy to improve exercise recovery due to the activity of its catechins with high antioxidant and anti-inflammatory potential. Here we performed a triple blinded placebo control experiment to determine the effect of green tea extract (GTE) from Camellia sinensis on muscle damage, oxidative stress, and neuromuscular activity in athletes submitted to consecutive sessions of exercise and fatigue. Sixteen trained amateur male athletes were randomly assigned to a GTE supplemented (500 mg/day) or placebo group during 15 days. Effects of supplementation were tested during repeated trials of submaximal cycling at 60% of peak power output performed after a protocol for cumulative fatigue of knee extensors. Muscle damage and oxidative stress showed lower magnitudes in response to fatigue after GTE supplementation. Placebo group showed impaired neuromuscular activity and higher muscle damage and oxidative stress compared to the GTE group during the cycling trials under fatigue. In summary, GTE supplementation showed positive effects on neuromuscular function in response to a condition of cumulative fatigue. It suggests GTE supplementation may have potential to serve as a strategy to improve performance and recovery in conditions of cumulative exercise.

Avaliação eletromiográfica dos músculos das costas no ciclismo: um estudo de caso

Here we quantified the electric neuromuscular activity of selected back muscles of a trained mountain bike cyclist without history of low back pain. For data collection, cyclist’ own bicycle was attached to a cycle simulator. The cyclist cycled at workload set between 70% and 80% of peak power output until exhaustion. Electromyography data was analyzed considering the root mean square values computed to represent the overall magnitude of activation. There was a general increase in the muscle activation for all the muscles analyzed. This behavior was remarked for trapezius descendens (2.4%) and iliocostalis (31.77%) in the non-preferred body side, whereas the longissimus increased activation (11.33%) in the preferred side. The increase in muscle activation without report of low back pain suggests that effects of fatigue were observed. The protocol was useful to elicit fatigue in back muscles and can serve to investigate muscular imbalances usually associated with low back pain and hip weakness. Descriptors : Back Pain; Cycling; Fatigue; Exercise; Spine; Muscle Activation.