Effect of body tilt angle on fatigue and EMG activities in lower limbs during cycling

This study compared the rate of fatigue and lower limb EMG activities during high-intensity constantload cycling in upright and supine postures. Eleven active males performed seven cycling exercise tests: one upright graded test, four fatigue tests (two upright, two supine) and two EMG tests (one upright, one supine). During the fatigue tests participants initially performed a 10 s all-out effort followed by a constant-load test with 10 s all-out bouts interspersed every minute. The load for the initial two fatigue tests was 80% of the peak power (PP) achieved during the graded test and these continued until failure. The remaining two fatigue tests were performed at 20% PP and were limited to the times achieved during the 80% PP tests. During the EMG tests subjects performed a 10 s all-out effort followed by a constant-load test to failure at 80% PP. Normalised EMG activities (% maximum, NEMG) were assessed in five lower limb muscles. Maximum power and maximum EMG activity prior to each fatigue and EMG test were unaffected by posture. The rate of fatigue at 80% PP was significantly higher during supine compared with upright posture (-68 ± 14 vs. -26 ± 6 W min-1, respectively, P\0.05) and the divergence of the fatigue responses occurred by the second minute of exercise. NEMG responses were significantly higher in the supine posture by 1–4 min of exercise. Results show that fatigue is significantly greater during supine compared with upright high-intensity cycling and this effect is accompanied by a reduced activation of musculature that is active during cycling.

Exercise performance and V0₂ kinetics during upright and recumbent high-intensity cycling exercise

This study investigated cycling performance and oxygen uptake (VO₂) kinetics between upright and two commonly used recumbent (R) postures, 65ºR and 30ºR. On three occasions, ten young active males performed three bouts of high-intensity constant-load (85% peak workload achieved during a graded test) cycling in one of the three randomly assigned postures (upright, 65ºR or 30ºR). The first bout was performed to fatigue and second and third bouts were limited to 7 min. A subset of seven subjects performed a final constant-load test to failure in the supine posture. Exercise time to failure was not altered when the body inclination was lowered from the upright (13.1 ± 4.5 min) to 65ºR (10.5 ± 2.7 min) and 30ºR (11.5 ± 4.6 min) postures; but it was significantly shorter in the supine posture (5.8 ± 2.1 min) when compared with the three inclined postures. Resulting kinetic parameters from a tri-exponential analysis of breath-by-breath VO₂ data during the first 7 min of exercise were also not different between the three inclined postures. However, inert gas rebreathing analysis of cardiac output revealed a greater cardiac output and stroke volume in both recumbent postures compared with the upright posture at 30 s into the exercise. These data suggest that increased cardiac function may counteract the reduction of hydrostatic pressure from upright ~25 mmHg; to 65ºR ~22 mmHg; and 30ºR ~18 mmHg such that perfusion of active muscle presumably remains largely unchanged, and also therefore, VO₂ kinetics and performance during high-intensity cycling.

Dose-dependent increases in heart rate variability and arterial compliance in overweight and obese adults with DHA-rich fish oil supplementation

Heart rate (HR) variability and large arterial compliance can be improved using fish oils. DHA, a component of fish oil, has cardiovascular health benefits, but its effect on HR variability (HRV) and arterial compliance is yet to be quantified. Sixty-seven overweight or obese adults (thirty-six males and thirty-one females; 53 (sem 2) year; BMI 31·7 (sem 1·1) kg/m²) were randomly allocated to consume either 6 g/d sunola oil (control; n 17), fish oil (260 mg DHA+60 mg EPA per g) at doses of 2 g/d (n 16), 4 g/d (n 17) or 6 g/d (n 17). Blood pressure, HR and compliance of large and small arteries were measured while supine at baseline and after 12 weeks in all participants, and HRV was assessed in a subgroup of forty-six participants. There was no effect of fish oil on blood pressure, small artery compliance or HR. However, the low frequency:high frequency ratio of HRV decreased with increasing doses of fish oil (r − 0·34, P = 0·02), while large artery compliance increased (r 0·34, P = 0·006). Moreover, the changes in these biomarkers were significantly correlated (r − 0·31, P = 0·04) and may reflect fish oil-induced improvements in arterial function and cardiac autonomic regulation.

Impact of bed rest on conduit artery remodeling: effect of exercise countermeasures

Physical inactivity is a potent stimulus for vascular remodeling, leading to a marked decrease in conduit artery diameter. However, little is known about the impact of physical inactivity on artery wall thickness or wall:lumen ratio or the potential of exercise countermeasures to modify artery wall thickness. The purpose of the study was to examine the impact of 60 days of bed rest, with or without exercise countermeasures, on carotid and superficial femoral artery wall thickness. Eighteen men were assigned to bed rest (second Berlin Bed Rest Study) and randomly allocated to control, resistive exercise, or resistive vibration exercise. Both exercise countermeasures were applied 3 times per week while the subjects were in the supine position on the bed. Sonography was used to examine baseline diameter and wall thickness of the carotid and femoral arteries. Bed rest decreased diameter of the superficial femoral artery (P=0.001) but not the carotid artery (P=0.29). Bed rest induced a significant increase in carotid and superficial femoral artery wall thickness (P=0.007 and 0.03) and wall:lumen ratio (P=0.009 and 0.001). Exercise prevented the increase in wall thickness of the carotid artery. In addition, exercise partly prevented the increased wall:lumen ratio in the superficial femoral artery. In conclusion, 8 weeks of bed rest resulted in approximately 20% increase in conduit artery wall thickness. Exercise countermeasures completely (carotid artery) or partly (superficial femoral artery) abolished the increase in wall thickness. These findings suggest that conduit artery wall thickness, a vascular characteristic associated previously with atherosclerosis, can rapidly adapt to physical inactivity and exercise in humans.

Integridade da pele em idosos: revisão da literatura segundo as cartas de promoção da saúde

Trata-se de uma revisão bibliográfica que objetivou relacionar as medidas educativas para a promoção da integridade da pele em idosos com as Cartas de Promoção da Saúde. Realizou-se a busca nas bases de dados CINAHL, SCOPUS, LILACS e COCHRANE, nos portais CAPES e BVS e na biblioteca PUBMED, mediante a aplicação dos descritores Health Education; Skin e Aged. Os resultados dos 7 artigos analisados apontaram como principais medidas educativas: inspeção diária da pele, cuidados com calçados e com os pés, uso regular de protetor solar e mudanças de decúbito. Essas medidas estavam relacionadas com as seguintes Cartas de Promoção da Saúde: Ottawa, Declaração de Santafé de Bogotá e Declaração de Jacarta. Conclui-se que as medidas educativas, baseadas nas Cartas, são de grande relevância para a criação de uma cultura de saúde, com enfoque na população e no indivíduo como agentes executores imprescindíveis para o alcance da promoção da saúde

Efeitos da reposição hidroeletrolítica sobre parâmetros cardiorrespiratórios em exercício e recuperação

INTRODUÇÃO: a necessidade de reposição ao máximo das perdas hídricas tornou-se estabelecida e difundida nos consensos internacionais. Entretanto, permanece pouco compreendida a influência da reposição quando administrada, igualmente, durante e após o exercício sobre parâmetros cardiorrespiratórios. OBJETIVO: analisar os efeitos da reposição hidroeletrolítica na frequência cardíaca (FC), pressão arterial sistólica (PAS), pressão arterial diastólica (PAD), saturação parcial de oxigênio (SpO2) e frequência respiratória (f) de jovens durante e após um exercício de longa duração. MÉTODOS: 31 jovens (21,55 ± 1,89 anos) realizaram três visitas ao laboratório (intervalo de 48 horas entre elas), sendo na primeira aplicado um teste incremental, para determinação da carga utilizada nas visitas seguintes, e nas duas últimas, denominadas protocolo controle (PC) e protocolo experimental (PE), os sujeitos foram submetidos a 10 min de repouso supino, 90 min de exercício em esteira ergométrica (60% do VO2pico) e 60 min de repouso supino. No PC não houve hidratação e no PE houve ingestão de solução isotônica. Os parâmetros FC, PAS, PAD, SpO2 e f foram mensurados no final do repouso; nos minutos 30, 60 e 90 do exercício, com exceção da f; e nos minutos 1, 3, 5, 7, 10, 20, 30, 40, 50 e 60 pós-exercício. Foi aplicado o teste t de Student ou teste de Mann-Whitney e ANOVA para medidas repetidas ou teste de Friedman seguidos de testes post hoc, com p < 0,05. RESULTADOS: a solução hidroeletrolítica proporcionou manutenção da PAS e da PAD, e menor incremento da FC durante o exercício; e promoveu retorno mais rápido da FC e conservou PAD, SpO2, PAS (a partir do 5º min) e f (a partir do 30º min) no período de recuperação. CONCLUSÃO: o protocolo de hidratação influenciou parâmetros cardiorrespiratórios de jovens durante e após a realização de atividade física submáxima de intensidade constante e longa duração.

Índices geométricos de variabilidade da frequência cardíaca na doença pulmonar obstrutiva crônica

Background: It was already evidenced decreased heart rate variability (HRV) in chronic obstructive pulmonary disease (COPD) patients at rest.Objective: In order to insert new elements in the literature regarding this issue, we evaluated geometric index of HRV in COPD subjects.Method: We analyzed data from 34 volunteers, divided into two groups according to spirometric values: COPD (17 volunteers, FEV1/FVC = 47.3 +/- 10.2; FEV1 = 50.8 +/- 15.7) and control (17 volunteers, FEV1/FVC = 78.8 +/- 10.8; FEV1 = 100.1 +/- 14.7). For analysis of HRV indexes the volunteers remained in the supine position for 30 minutes. We analyzed the following indexes: triangular index (RRtri), triangular interpolation of RR intervals (TINN) and Poincare plot (SD1, SD2 and SD1/SD2). Student t test for unpaired samples and Mann-Whitney test were used for data analysis.Results: We observed statistically significant reductions in geometric indexes in the COPD group: RRtri (0.043 +/- 0.01 vs. 0.059 +/- 0.02; p = 0.018), TINN (105.88 +/- 51.82 vs. 151.47 +/- 49.9; p=0.014), SD1 (9.76 +/- 4.66 vs. 14.55 +/- 6.04; p = 0.014) and SD2 (34.86 +/- 17.02 vs. 51.51 +/- 18.38; p = 0.010). SD1/5D2 (0.30 +/- 0.11 vs. 0.28 +/- 0.07; p = 0.605) were not significantly different between groups. Patients with COPD presented a visual analysis of Poincare plot of lower dispersion of RR intervals both beat to beat and the long term.Conclusion: Subjects with COPD present reduction of geometric indexes of HRV, indicating reduced heart rate variability. (C) 2010 Sociedade Portuguesa de Pneumologia. Published by Elsevier Espana, S.L. All rights reserved.

Fractal correlation property of heart rate variability in chronic obstructive pulmonary disease

Background: It was reported that autonomic nervous system function is altered in subjects with chronic obstructive pulmonary disease (COPD). We evaluated short-and long-term fractal exponents of heart rate variability (HRV) in COPD subjects.Patients and methods: We analyzed data from 30 volunteers, who were divided into two groups according to spirometric values: COPD (n = 15) and control (n = 15). For analysis of HRV indices, HRV was recorded beat by beat with the volunteers in the supine position for 30 minutes. We analyzed the linear indices in the time (SDNN [standard deviation of normal to normal] and RMSSD [root-mean square of differences]) and frequency domains (low frequency [LF], high frequency [HF], and LF/HF), and the short-and long-term fractal exponents were obtained by detrended fluctuation analysis. We considered P < 0.05 to be a significant difference.Results: COPD patients presented reduced levels of all linear exponents and decreased short-term fractal exponent (alpha-1: 0.899 +/- 0.18 versus 1.025 +/- 0.09, P = 0.026). There was no significant difference between COPD and control groups in alpha-2 and alpha-1/alpha-2 ratio.Conclusion: COPD subjects present reduced short-term fractal correlation properties of HRV, which indicates that this index can be used for risk stratification, assessment of systemic disease manifestations, and therapeutic procedures to monitor those patients.

Força muscular respiratória, qualidade de vida e modulação autonômica da frequência cardíaca na distrofia miotônica

Background: The myotonic dystrophy (MD) is a multisystem neuromuscular disease that can affect the respiratory muscles and heart function, and cause impairment in quality of life. Objectives: Investigate the changes in respiratory muscle strength, health-related quality of life (HRQoL) and autonomic modulation heart rate (HR) in patients with MD. Methods: Twenty-three patients performed assessment of pulmonary function, sniff nasal inspiratory pressure (SNIP), the maximal inspiratory (MIP) and expiratory (MEP) pressure, and of HRQoL (SF-36 questionnaire). Of these patients, 17 underwent assessment of heart rate variability (HRV) at rest, in the supine and seated positions. Results: The values of respiratory muscle strength were 64, 70 and 80% of predicted for MEP, MIP, and SNIP, respectively. Significant differences were found in the SF-36 domains of physical functioning (58.7 ± 31,4 vs. 84.5 ± 23, p<0.01) and physical problems (43.4 ± 35.2 vs. 81.2 ± 34, p<0.001) when patients were compared with the reference values. Single linear regression analysis demonstrated that MIP explains 29% of the variance in physical functioning, 18% of physical problems and 20% of vitality. The HRV showed that from supine position to seated, HF decreased (0.43 x 0.30), and LF (0.57 x 0.70) and the LF/HF ratio (1.28 x 2.22) increased (p< 0.05). Compared to healthy persons, LF was lower in both male patients (2.68 x 2.99) and women (2.31 x 2.79) (p< 0.05). LF / HF ratio and LF were higher in men (5.52 x 1.5 and 0.8 x 0.6, p <0.05) and AF in women (0.43 x 0.21) (p< 0.05). There was positive correlation between the time of diagnosis and LF / HF ratio (r = 0.7, p <0.01). Conclusions: The expiratory muscle strength was reduced. The HRQoL was more impaired on the physical aspects and partly influenced by changes in inspiratory muscle strength. The HRV showed that may be sympathetic dysfunction in autonomic modulation of HR, although with normal adjustment of autonomic modulation during the change of posture. The parasympathetic modulation is higher in female patients and sympathetic tends to increase in patients with longer diagnosis

Ergonomics work analysis applied to dentistry - a Brazilian case study

This paper presents the Ergonomic Work Analysis method in a Brazilian Dentist's office. Through the study, the constraints and the strategies in avoiding them were identified. It was found that dentists hardly use the position most indicated by the International Organization for Standardization (ISO) and the Federation Dentaire Internacionale (FDI) for both the patient and the dentist, which is respectively supine and 9 o'clock, due to the limited space and layout. Five types of treatments performed by the professional have been studied. The frequency and duration of actions in these treatments were accounted for and the standard positions adopted were identified. The AET was found to be a very suitable method to grasp the dentist's activity and build a point of view of the profession, which is characterized as: stressful, perfectionist and restrictive. Time management is presented as an important strategy to control the tension arising from performing the treatments.

Relação entre desenvolvimento motor corporal e aquisição de habilidades orais

TEMA: a literatura aponta para a influência da postura corporal sobre as habilidades orais em crianças com desenvolvimento sensório-motor alterado. em crianças normais existem poucos estudos sobre essa relação. OBJETIVO: estudar em crianças a termo a relação entre habilidades motoras e habilidades motoras orais, desde 1 dia de vida até 24 meses de idade. MÉTODO: 42 crianças foram filmadas com 1 dia, 1 mês, 2, 3, 4, 5, 6, 9,12 e 24 meses nas posições supino, prono, sentado e em pé e durante alimentação com amamentação / mamadeira (até 5 meses), uso de colher para alimentação pastosa (3 aos 12 meses), uso de copo para água ou suco (6 aos 24 meses) e alimento sólido (6 aos 24 meses). Estabeleceram-se escores de quantificação para o desenvolvimento corporal e habilidades orais e utilizou-se o coeficiente de correlação de Pearson para o estudo estatístico, adotando-se nível de significância de 5%. RESULTADOS: os resultados do desenvolvimento motor apontaram para semelhança de dados entre supino e prono e sentado e em pé; para as habilidades orais (durante a alimentação com mamadeira/amamentação, colher, copo, mastigação) constatou-se em cada modalidade de alimentação, homogeneidade de aquisição de habilidades para lábios, língua e mandíbula. Houve associação entre habilidades motoras e orais; resultados apontam que o desenvolvimento motor (habilidades motoras) se deu antes das orais desde o 5° ao 24° mês e que as habilidades de mandíbula em copo e colher ocorreram antes das habilidades de lábios e língua. CONCLUSÃO: houve crescente aquisição de habilidades motoras e orais, variabilidade de habilidades em idades entre 3 e 24 meses e associação entre habilidades motoras e orais.

The Anatomy of the Thoracic Spinal Canal Investigated with Magnetic Resonance Imaging

BACKGROUND: We investigated, with magnetic resonance imaging, the distance of the dura mater to the spinal cord in patients without spinal or medullar disease at the 2nd, 5th, and 10th thoracic segments.METHODS: Fifty patients in the supine position underwent magnetic resonance imaging. Medial sagittal slices of the 2nd, 5th, and 10th thoracic segments were measured for the relative distances using the 1.5-T superconducting system (Gyroscan Intera, Philips Medical Systems, Best, the Netherlands). In 10 patients, the angles relative to the tangent at the insertion point on the skin were measured.RESULTS: The posterior dural-spinal cord distance is significantly greater at the midthoracic region (5th thoracic = 5.8 +/- 0.8 mm) than at the upper (2nd thoracic = 3.9 +/- 0.8 mm) and lower thoracic levels (10th thoracic = 4.1 +/- 1.0 mm) (P < 0.015). There were no differences between interspaces T2 and 110. There was no correlation between age and the measured distance between the dura mater and the spinal cord. The entry angle of the needle at T2 was 9.0 degrees +/- 2.5 degrees; at T5, 45.0 degrees +/- 7.4 degrees; and at T10, 9.50 degrees +/- 4.2 degrees.CONCLUSIONS: This study demonstrated that there is greater depth of the posterior subarachnoid space at the T2, T5, and T10 levels. The greater distance was found at T5. (Anesth Analg 2010;110:1494-5)

Aging reduces complexity of heart rate variability assessed by conditional entropy and symbolic analysis

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Peridural com ropivacaina a 1%: Experiencia com volume proporcional a estatura

Background and Objectives - Ropivacaine - a local amino amide anesthetic agent - is a plain S enantiomer which makes it a potent and low toxicity drug. The aim of our study was to evaluate 1% ropivacaine for epidural block in lower doses than those described in the literature. Methods - Thirty-eight patients, physical status ASA I and II, aged 15 to 70 years, weighing 50 to 100 kg were selected. Premedication consisted of 15 mg oral midazolam given 60 min before anesthesia induction. In the OR, after standard monitoring a catheter was inserted intravenously to administer 10 ml.kg-1 Ringers lactate solution. Epidural puncture was performed with the patient in the sitting position and 1% ropivacaine was administered in a volume corresponding to 10% of patient's height in centimeters. With the patient in the supine position, motor blockade intensity, temperature sensitivity and sensory block extension at 1, 3, 5, 7, 10, 15, 20, 30 minutes after drug injection were evaluated. Blood pressure, heart rate and adverse side effects during the course of anesthesia and in the post-anesthetic period were also observed. In the recovery room patients were followed-up until motor blockade intensity temperature sensitivity and sensory block had returned to level L2. Results - Mean values were 41.4 years of age, 68.8 kg of body weight and 165 cm height. Upper thermal blockade level was T4 and upper sensory block level was T6. Most patients showed motor block level 1 (Bromage scale) after 30 minutes of observation. Motor block mean duration was 254 minutes and temperature sensitivity 426 minutes. Only three patients had complications: two cases of hypotension and one of bradycardia. Conclusions - In the volumes used in this study, ropivacaine produced adequate analgesia and a less intense lower limb motor block which, however, was sufficient to allow for surgical procedures with low incidence of side-effects.

Electromyographic validation of the trapezius and serratus anterior muscles in frontal-lateral cross, dumbbells exercises

Based on the lack of electromyographic researches on sport and programmes of physical conditioning, we can say that it is necessary to reexamine some exercises routinely used in the programmes of physical conditioning. Thus, the trapezius and serratus anterior muscles were studied electromyographically so that we could evaluate the validity in some ways of execution of the frontal-lateral cross, dumbbells exercises for the development of these muscles. We analyzed 24 male volunteers, 18 to 25 years old, using a 2-channel TECA TE 4 electromyograph and Hewlett Packard surface electrodes. For the execution of the exercise it was used a supine bench, a straight board and two bars of 40 cm made of light wood. The results showed that TS acted preferentially in standing modality and in the inclined supine modality, however with activity levels that do not justify its inclusion in physical fitness programmes.