The Influence of Hip and Knee Joint Angles on Quadriceps Muscle-Tendon Unit Properties during Maximal Voluntary Isometric Contraction.

Determining how the quadriceps femoris musculotendinous unit functions, according to hip and knee joint angles, may help with clinical decisions when prescribing knee extension exercises. We aimed to determine the effect of hip and knee joint angles on structure and neuromuscular functioning of all constituents of the quadriceps femoris and patellar tendon properties. Twenty young males were evaluated in four positions: seated and supine in both 20° and 60° of knee flexion (SIT20, SIT60, SUP20, and SUP60). Peak knee extension torque was determined during maximal voluntary isometric contraction (MVIC). Ultrasound imaging was used at rest and during MVIC to characterize quadriceps femoris muscle and tendon aponeurosis complex stiffness. We found that peak torque and neuromuscular efficiency were higher for SUP60 and SIT60 compared to SUP20 and SIT20 position. We found higher fascicle length and lower pennation angle in positions with the knee flexed at 60°. The tendon aponeurosis complex stiffness, tendon force, stiffness, stress, and Young's modulus seemed greater in more elongated positions (60°) than in shortened positions (20°). In conclusion, clinicians should consider positioning at 60° of knee flexion rather than 20°, regardless if seated or supine, during rehabilitation to load the musculotendinous unit enough to stimulate a cellular response.

Hip and Knee Joint Angles Determine Fatigue Onset during Quadriceps Neuromuscular Electrical Stimulation.

Neuromuscular electrical stimulation (NMES) has been used to increase muscle strength and physical function. However, NMES induces rapid fatigue, limiting its application. To date, the effect of quadriceps femoris (QF) muscle length by knee and hip joint manipulation on NMES-induced contraction fatigability is not clear. We aimed to quantify the effects of different muscle lengths on NMES-induced contraction fatigability, fatigue index, and electromyographic (EMG) activity for QF muscle. QF maximum evoked contraction (QMEC) was applied in a 26 min protocol (10 s on; 120 s off; 12 contractions) in 20 healthy participants (24.0 ± 4.6 years old), over 4 sessions on different days to test different conditions. The tested conditions were as follows: supine with knee flexion of 60° (SUP60), seated with knee flexion of 60° (SIT60), supine with knee flexion of 20° (SUP20), and seated with knee flexion of 20° (SIT20). Contraction fatigability (torque decline assessed by maximal voluntary contraction [MVC] and during NMES), fatigue index (percentage reduction in MVC), and EMG activity (root mean square [RMS] and median frequency) of the superficial QF' constituents were assessed. After NMES, all positions except SUP20 had an absolute reduction in MVC (p < .001). Fatigue index was greater in SIT20 than in SIT60 (p < .001) and SUP20 (p = .01). There was significant torque reduction across the 12 QMEC in SUP60 and SIT60, up to 10.5% (p < .001-.005) and 9.49% (p < .001-.033), respectively. There was no torque reduction during NMES in SUP20 and SIT20. Fatigue was accompanied by an increase in RMS (p = .032) and a decrease in median frequency for SUP60 (p < .001). Median frequency increased only in the SUP20 condition (p = .021). We concluded that QF NMES-induced contraction fatigability is greater when the knee is flexed at 60° compared to 20°. In addition, a supine position promotes earlier fatigue for a 60° knee flexion, but it delays fatigue onset for a 20° knee flexion compared to the seated position. These results provide a rationale for lower limb positioning during NMES, which depends on training objectives, e.g., strengthening or task-specific functionality training.

Short-term cardiopulmonary rehabilitation program in a post-COVID-19 patient: a case report / Protocolo de reabilitação cardiopulmonar de curto período em um paciente pós-COVID 19: relato de caso

We aimed to report a successful clinical case of a short-term cardiopulmonary rehabilitation after hospital discharge due to COVID-19. Exploratory descriptive case study with a 58-year-old male, former smoker, and in need of supplemental oxygen after COVID-19 infection, admitted to a car-diopulmonary rehabilitation program of six weeks in a school clinic in the Federal District, Brasília, Brazil. Chest expansion, aerobic capacity, physical function, and quality of life were evaluated before and after the program using, respectively, thoracic cirtometry, 6-Minute Walk Test, 1-Minute Sit-To-Stand Test, and Short Form Health Survey. At the end of the cardiopulmonary rehabilitation, the patient presented increased chest expansion, increased walked distance with decreased percep-tion of exertion, increased repetitions in the 1-minute sit-to-stand-test, and increased quality of life. Moreover, he was completely weaned from supplemental oxygen. A short-term duration cardiopul-monary rehabilitation protocol can contribute to improvement in aerobic and functional capacity, and in quality of life after COVID-19

O objetivo deste estudo foi relatar um caso clínico bem-sucedido de reabilitação cardiopulmonar de curta duração após alta hospitalar pós COVID-19. Trata-se de um estudo de caso exploratório descritivo com um homem de 58 anos, ex-tabagista e com necessidade de suplementação de oxigênio após infecção por CO-VID-19, admitido em um programa de reabilitação cardiopulmonar de seis semanas em uma clínica escola do Distrito Federal ­ Brasília, Brasil. A expansão torácica, capacidade aeróbia, função física e qualidade de vida foram avaliadas antes e após o programa por meio de cirtometria torácica, teste de caminhada de 6 minutos, teste de sentar e levantar de 1 minuto e Short Form Health Survey, respectivamente. Ao final da reabilitação cardiopulmonar, o paciente apresentou aumento da expansão torácica, aumento da distância percorrida com diminuição da percepção de esforço, aumento das repetições no teste de sentar e levantar de 1 minuto e aumento da qualidade de vida. Além disso, o desmame completo do oxigênio suplementar também foi alcançado. Um protocolo de reabilitação cardiopulmonar, ainda que de curta duração, pode contribuir para a melhora da capacidade aeróbica, funcional e da qualidade de vida após a COVID-19

The Effect of Quadriceps Muscle Length on Maximum Neuromuscular Electrical Stimulation Evoked Contraction, Muscle Architecture, and Tendon-Aponeurosis Stiffness.

Muscle-tendon unit length plays a crucial role in quadriceps femoris muscle (QF) physiological adaptation, but the influence of hip and knee angles during QF neuromuscular electrical stimulation (NMES) is poorly investigated. We investigated the effect of muscle length on maximum electrically induced contraction (MEIC) and current efficiency. We secondarily assessed the architecture of all QF constituents and their tendon-aponeurosis complex (TAC) displacement to calculate a stiffness index. This study was a randomized, repeated measure, blinded design with a sample of twenty healthy men aged 24.0 ± 4.6. The MEIC was assessed in four different positions: supine with knee flexion of 60° (SUP60); seated with knee flexion of 60° (SIT60); supine with knee flexion of 20° (SUP20), and seated with knee flexion of 20° (SIT20). The current efficiency (MEIC/maximum tolerated current amplitude) was calculated. Ultrasonography of the QF was performed at rest and during NMES to measure pennation angle (θ p ) and fascicle length (L f ), and the TAC stiffness index. MEIC and current efficiency were greater for SUP60 and SIT60 compared to SUP20 and SIT20. The vastus lateralis and medialis showed lower θ p and higher L f at SUP60 and SIT60, while for the rectus femoris, in SUP60 there were lower θ p and higher L f than in all positions. The vastus intermedius had a similar pattern to the other vastii, except for lack of difference in θ p between SIT60 compared to SUP20 and SIT20. The TAC stiffness index was greater for SUP60. We concluded that NMES generate greater torque and current efficiency at 60° of knee flexion, compared to 20°. For these knee angles, lengthening the QF at the hip did not promote significant change. Each QF constituent demonstrated muscle physiology patterns according to hip and/or knee angles, even though a greater L f and lower θ p were predominant in SUP60 and SIT60. QF TAC index stiffened in more elongated positions, which probably contributed to enhanced force transmission and slightly higher torque in SUP60. Our findings may help exercise physiologist better understand the impact of hip and knee angles on designing more rational NMES stimulation strategies. CLINICAL TRIAL REGISTRATION: www.ClinicalTrials.gov, identifier NCT03822221.

[Lifestyle of adolescent students from public and private schools in Recife: ERICA]. / Estilo de vida de adolescentes estudantes de escolas públicas e privadas em Recife: ERICA.

This study analyzes the behavior patterns related to the lifestyle of adolescents in Recife, Brazil. A cross-sectional study was conducted with data from the Cardiovascular Risk Study among Adolescents (ERICA) and 2400 students aged 12 to 17 were interviewed. The prevalence of physical activity, eating behavior, smoking and alcohol consumption were analyzed. The Chi-square test and 95% confidence interval (95%CI) were used to evaluate the statistical significance of the measurements. It was observed that 60% of the adolescents presented inadequate eating behaviors regarding the consumption of breakfast, daily water intake and meals eaten in front of the TV. About 40% (95%CI: 39.7-45) did not sit down to meals with their parents or guardians. The prevalence of physical inactivity was 52.4% (95%CI: 50-55). Female adolescents were more inactive (68.7%, 95%CI: 65-72) than males (36.4%, 95%CI: 33-40). Teenagers of economic classes D and E were the most inactive (60.7%, 95%CI: 46-73). Alcohol consumption was 18.7% (95%CI: 2.6-5.6) and smoking was prevalent in 3.8% (95%CI: 2-6) of the individuals. Inadequate eating behaviors and physical inactivity were the main areas responsible for an unhealthy lifestyle, followed by alcohol consumption and smoking.

Este estudo analisa os comportamentos relacionados ao estilo de vida de adolescentes em Recife, Brasil. Estudo transversal com dados do Estudo de Riscos Cardiovasculares em Adolescentes (ERICA). 2.400 estudantes de 12 a 17 anos foram entrevistados. Foram analisadas as prevalências de atividade física, comportamento alimentar, tabagismo e consumo de álcool. O teste Qui-quadrado e Intervalo de confiança 95% (IC95%) foram usados para avaliar a significância estatística das medidas. Observou-se 60% dos adolescentes com comportamentos alimentares inadequados quanto ao consumo de café da manhã, água/dia e refeições em frente à TV. Cerca de 40% (IC95%: 39,7-45) não realizavam refeições com os pais ou responsáveis. A prevalência de inatividade física foi de 52,4% (IC95%: 50-55). Adolescentes do sexo feminino foram mais inativas (68,7%; IC95%: 65-72) em relação aos meninos (36,4%; IC95%: 33-40). Adolescentes das classes econômicas D e E foram os mais inativos (60,7%; IC95%: 46-73). O consumo de bebida alcoólica foi de 18,7% (IC95%: 2,6-5,6) e o tabagismo foi de 3,8% (IC95%: 2-6) dos indivíduos. Comportamentos alimentares inadequados e a inatividade física foram os principais domínios responsáveis por um estilo de vida não saudável, seguidos pelo consumo de álcool e tabagismo.

Estilo de vida de adolescentes estudantes de escolas públicas e privadas em Recife: ERICA / Lifestyle of adolescent students from public and private schools in Recife: ERICA

Resumo Este estudo analisa os comportamentos relacionados ao estilo de vida de adolescentes em Recife, Brasil. Estudo transversal com dados do Estudo de Riscos Cardiovasculares em Adolescentes (ERICA). 2.400 estudantes de 12 a 17 anos foram entrevistados. Foram analisadas as prevalências de atividade física, comportamento alimentar, tabagismo e consumo de álcool. O teste Qui-quadrado e Intervalo de confiança 95% (IC95%) foram usados para avaliar a significância estatística das medidas. Observou-se 60% dos adolescentes com comportamentos alimentares inadequados quanto ao consumo de café da manhã, água/dia e refeições em frente à TV. Cerca de 40% (IC95%: 39,7-45) não realizavam refeições com os pais ou responsáveis. A prevalência de inatividade física foi de 52,4% (IC95%: 50-55). Adolescentes do sexo feminino foram mais inativas (68,7%; IC95%: 65-72) em relação aos meninos (36,4%; IC95%: 33-40). Adolescentes das classes econômicas D e E foram os mais inativos (60,7%; IC95%: 46-73). O consumo de bebida alcoólica foi de 18,7% (IC95%: 2,6-5,6) e o tabagismo foi de 3,8% (IC95%: 2-6) dos indivíduos. Comportamentos alimentares inadequados e a inatividade física foram os principais domínios responsáveis por um estilo de vida não saudável, seguidos pelo consumo de álcool e tabagismo.

Abstract This study analyzes the behavior patterns related to the lifestyle of adolescents in Recife, Brazil. A cross-sectional study was conducted with data from the Cardiovascular Risk Study among Adolescents (ERICA) and 2400 students aged 12 to 17 were interviewed. The prevalence of physical activity, eating behavior, smoking and alcohol consumption were analyzed. The Chi-square test and 95% confidence interval (95%CI) were used to evaluate the statistical significance of the measurements. It was observed that 60% of the adolescents presented inadequate eating behaviors regarding the consumption of breakfast, daily water intake and meals eaten in front of the TV. About 40% (95%CI: 39.7-45) did not sit down to meals with their parents or guardians. The prevalence of physical inactivity was 52.4% (95%CI: 50-55). Female adolescents were more inactive (68.7%, 95%CI: 65-72) than males (36.4%, 95%CI: 33-40). Teenagers of economic classes D and E were the most inactive (60.7%, 95%CI: 46-73). Alcohol consumption was 18.7% (95%CI: 2.6-5.6) and smoking was prevalent in 3.8% (95%CI: 2-6) of the individuals. Inadequate eating behaviors and physical inactivity were the main areas responsible for an unhealthy lifestyle, followed by alcohol consumption and smoking.

Análise da força muscular expiratória e respiração espontânea de indivíduos em ventilação mecânica: estudo transversal / El análisis de la fuerza muscular espiratoria y la respiración espontánea de los individuos en ventilación mecánica: el estudio transversal / Analysis of expiratory muscle strength and spontaneous breathing of individuals on mechanical ventilation: a cross-sectional study

RESUMO Os músculos da expiração têm funções em todo o ciclo respiratório, mas não são frequentemente avaliados no desmame da ventilação mecânica. Assim, revisões e consensos não mencionam a pressão expiratória máxima (PEmáx) e o treino expiratório. Objetivou-se investigar a relação da força muscular expiratória com a respiração espontânea de indivíduos ventilados mecanicamente. Trata-se de um estudo transversal com participantes de 18 a 79 anos de idade. Foram formados os grupos PEmáx satisfatória (GPES) e PEmáx baixa (GPEB) conforme o ponto de corte de 55cmH2O e comparados a parâmetros de desmame. O GPES (n=9) teve desempenho superior ao do GPEB (n=21) no índice de respiração rápida e superficial (IRRS) (40,6±17,6rpm/L e 75,3±44,1rpm/L, respectivamente; p=0,022) e na frequência respiratória (f) (19,1±6,2rpm e 26,1±9,4rpm; p=0,044). A prevalência de PEmáx satisfatória foi pequena, observada no tamanho dos grupos. Além disso, embora a PEmáx percentual do valor predito tenha sido menor no GPEB, como esperado (67,2±15,4% vs. 45,8±14,7%; p=0,001), a pressão inspiratória máxima percentual não diferiu significantemente (82,4±21,8% vs. 67,8±18,4%; p=0,077). A PEmáx se correlacionou moderadamente com o IRRS (r=-0,406; p=0,026) e com a f (r=-0,426; p=0,017). Conclui-se que a PEmáx≥55cmH2O esteve associada à melhores valores no IRRS e na f, e que a redução da força muscular expiratória foi mais prevalente e severa que a da força muscular inspiratória.

RESUMEN Los músculos de la espiración tienen funciones en todo el ciclo respiratorio, sin embargo, no son frecuentemente evaluados en el desmame de la ventilación mecánica. Así, revisiones y consensos no mencionan la tensión espiratoria máxima (PEmáx) y el entreno espiratorio. Se ha objetivado investigar la relación de la fuerza muscular espiratoria con la respiración espontánea de los individuos ventilados mecánicamente. Se trata de un estudio transversal con participantes de 18 a 79 años de edad. Han sido hechos los grupos PEmáx satisfactoria (GPES) y PEmáx baja (GPEB) de acuerdo con el punto de corte de 55cmH2O y han sido comparados a parámetros de destete. El GPES (n=9) ha tenido el desempeño superior al del GPEB (n=21) en el índice de respiración rápida y superficial (IRRS) (40,6±17,6rpm/L y 75,3±44,1rpm/L, respectivamente; p=0,022) y en la frecuencia respiratoria (f) (19,1±6,2rpm y 26,1±9,4rpm; p=0,044). La prevalencia de PEmáx satisfactoria ha sido pequeña, ha sido observada en el tamaño de los grupos. Además de eso, aunque la PEmáx porcentual del valor predicho haya sido menor en el GPEB, como ha sido esperado (67,2±15,4% vs. 45,8±14,7%; p=0,001), la presión inspiratoria máxima porcentual no ha diferido significantemente (82,4±21,8% vs. 67,8±18,4%; p=0,077). La PEmáx se ha correlacionado moderadamente con el IRRS (r=-0,406; p=0,026) y con la f (r=-0,426; p=0,017). Se concluye que la PEmáx≥55cmH2O ha estado asociada a los mejores valores en el IRRS y en la f, y que la reducción de la fuerza muscular espiratoria ha sido más prevalente y severa que la de la fuerza muscular inspiratoria.

ABSTRACT The expiratory muscles have functions throughout the respiratory cycle, but they are not often evaluated in the weaning from mechanical ventilation. Thus, reviews and consensus do not mention the maximal expiratory pressure (MEP) and the expiratory training. The aim of this study was to investigate the relationship of expiratory muscle strength with the spontaneous breathing of individuals on mechanical ventilation. This is a cross-sectional study with participants aged between 18 and 79 years. The groups satisfactory MEP (SMEPG) and low MEP (LMEPG) were formed according to the cut-off point of 55 cmH2O and compared to weaning parameters. The SMEPG (n=9) had better performance than LMEPG (n=21) in the rapid shallow breathing index (RSBI) (40.6±17.6 bpm/L and 75.3±44.1 bpm/L, respectively; p=0.022) and in the respiratory rate (RR) (19.1±6.2 bpm and 26.1±9.4 bpm; p=0.044). Prevalence of satisfactory MEP was low, as observed in the size of groups. In addition, although the MEP percentage of the predicted value was lower in LMEPG, as expected (67.2±15.4% vs. 45.8±14.7%; p=0.001), the percentage for maximal inspiratory pressure was not significantly different (82.4±21.8% vs. 67.8±18.4%; p=0.077). The MEP was moderately correlated with the RSBI (r=−0.406; p=0.026) and with the RR (r=−0.426; p=0.017). It was concluded that MEP≥55 cmH2O was associated with better values in RSBI and RR and that the reduction of expiratory muscle strength was more prevalent and severe than that of inspiratory muscle strength.