RESUMO
OBJECTIVE: The goal of this study was to compare erector spinae muscle fatigue, upper limb muscle activity, body areas discomfort, and heart rate during a 10-min carrying task with and without a passive upper-body exoskeleton (CarrySuitâ) while considering sex influences. BACKGROUND: Passive exoskeletons are commercially available to assist lifting or carrying task. However, evidence of their impact on muscle activity, fatigue, heart rate and discomfort are scarce and/or do not concur during carrying tasks. METHOD: Thirty participants (16 females and 14 male) performed a 10-min, 15kg load-carrying task with and without the exoskeleton in two non-consecutive days. Heart rate, and erector spinae, deltoid, biceps and brachioradialis muscle activity were recorded during the carrying tasks. In addition, erector spinae electromyography during an isometric hold test and discomfort ratings were measured before and after the task. RESULTS: While without the exoskeleton upper limb muscle activity increased or remained constant during the carrying task and showing high peak activation for both males and females, a significant activity reduction was observed with the exoskeleton. Low back peak activation, heart rate and discomfort were lower with than without the exoskeleton. In males muscle activation was significantly asymmetric without the exoskeleton and more symmetric with the exoskeleton. CONCLUSION: The tested passive exoskeleton appears to alleviate the physical workload and impact of carrying heavy loads on the upper limbs and lower back for both males and females.
Assuntos
Exoesqueleto Energizado , Feminino , Humanos , Masculino , Frequência Cardíaca , Músculo Esquelético/fisiologia , Eletromiografia , Dorso/fisiologia , Músculos Paraespinais , Fenômenos BiomecânicosRESUMO
Overloaded backpacks can cause changes in posture and gait dynamic balance. Therefore, the aim of this study was to assess gait regularity and local dynamic stability in young adults as they carried a backpack in different positions, and with different loads. Twenty-one healthy young adults participated in the study, carrying a backpack that was loaded with 10 and 20% of their body weight (BW). The participants walked on a level treadmill at their preferred walking speeds for 4 min under different conditions of backpack load and position (i.e. with backpack positioned back bilaterally, back unilaterally, frontally or without a backpack). Results indicate that backpack load and positioning significantly influence gait stability and regularity, with the exception of the 10% BW bilateral back position. Therefore, the recommended safe load for school-age children and adolescents (10% of BW) should also be considered for young adults. Practitioner summary: Increase in load results in changes in posture, muscle activity and gait parameters, so we investigated the gait adaptations related to regularity and stability. Conditions with high backpack loads significantly influenced gait stability and regularity in a position-dependent manner, except for 10% body weight bilateral back position.
Assuntos
Fenômenos Biomecânicos/fisiologia , Caminhada/fisiologia , Suporte de Carga/fisiologia , Adolescente , Adulto , Análise de Variância , Dorso/fisiologia , Feminino , Marcha , Humanos , Cinesiologia Aplicada , Masculino , Postura , Análise e Desempenho de Tarefas , Adulto JovemRESUMO
Changes in range of motion affect the magnitude of the load during the squat exercise and, consequently, may influence muscle activation. The purpose of this study was to evaluate muscle activation between the partial and full back squat exercise with external load equated on a relative basis between conditions. Fifteen young, healthy, resistance-trained men (age: 26 ± 5 years, height: 173 ± 6 cm) performed a back squat at their 10 repetition maximum (10RM) using 2 different ranges of motion (partial and full) in a randomized, counterbalanced fashion. Surface electromyography was used to measure muscle activation of the vastus lateralis, vastus medialis, rectus femoris, biceps femoris (BF), semitendinosus, erector spinae, soleus (SL), and gluteus maximus (GM). In general, muscle activity was highest during the partial back squat for GM (p = 0.004), BF (p = 0.009), and SL (p = 0.031) when compared with full-back squat. There was no significant difference for rating of perceived exertion between partial and full back squat exercise at 10RM (8 ± 1 and 9 ± 1, respectively). In conclusion, the range of motion in the back squat alters muscle activation of the prime mover (GM) and stabilizers (SL and BF) when performed with the load equated on a relative basis. Thus, the partial back squat maximizes the level of muscle activation of the GM and associated stabilizer muscles.
Assuntos
Músculo Esquelético/fisiologia , Treinamento Resistido/métodos , Adulto , Dorso/fisiologia , Eletromiografia , Exercício Físico/fisiologia , Músculos Isquiossurais/fisiologia , Humanos , Masculino , Músculo Quadríceps/fisiologia , Amplitude de Movimento Articular/fisiologia , Coxa da Perna/fisiologia , Adulto JovemRESUMO
This study compared abdominal electromyographic (EMG) activity during the performance of Pilates' exercises. 16 females participated in the study. EMG signals of the rectus abdominis (RA) and external oblique (EO) were recorded during Longspine performed on the mat, Cadillac, and Reformer and the Teaser performed on the mat, Cadillac, and Combo-chair. Values were normalized by the EMG peak of a dynamic task and divided in concentric and eccentric phases. Longspine performed on the mat increased EO activity in the concentric phase more than on the Reformer and the Cadillac (Mean Difference (MD)=12.2%; 95% Confidence Interval (CI) [3.36; 21.04]; p=.04). Differences in the eccentric phase of the RA favored the mat compared to the Reformer (MD=5.20%; 95% CI [-0.55; 10.95]; p=.02). Significant differences in eccentric contraction of the RA were found for teaser exercise performed on the mat versus Cadillac (MD=1.1%; 95% CI [-4.13; 6.33]; p=.04) and the mat versus the Combo-chair (MD=6.3%; 95% CI [1.31; 11.29]; p=.005). Higher concentric activation values for the EO were found when the teaser exercise was performed on the Cadillac. Exercises performed on the mat required greater rectus abdominis activation.
Assuntos
Eletromiografia/métodos , Músculo Esquelético/fisiologia , Tronco/fisiologia , Músculos Abdominais/fisiologia , Adulto , Dorso/fisiologia , Exercício Físico/fisiologia , Feminino , Humanos , Movimento , Reto do Abdome/fisiologia , Coluna Vertebral/fisiologia , Adulto JovemRESUMO
BACKGROUND AND OBJECTIVE: Poor back endurance is a predictor of low back pain. Few studies have investigated back muscle fatigue in older people. The purpose of this study was to compare the back muscle fatigue by endurance time and perceived effort between young and older adults during dynamic exercise. METHOD: Sixteen older and 16 young adults, all healthy, participated in this study. The subjects performed a fatiguing trunk extension-flexion exercise on a Roman chair until exhaustion. Endurance time and perceived muscle fatigue (Borg CR-10 scale) were used as fatigue criteria. RESULTS: The older adults were significantly (T
Assuntos
Envelhecimento/fisiologia , Dorso/fisiologia , Exercício Físico/fisiologia , Dor Lombar/fisiopatologia , Fadiga Muscular/fisiologia , Resistência Física/fisiologia , Adulto , Fatores Etários , Idoso , Feminino , Voluntários Saudáveis , Humanos , Dor Lombar/diagnóstico , Dor Lombar/reabilitação , Masculino , Pessoa de Meia-Idade , Valor Preditivo dos Testes , Tronco/fisiologia , Adulto JovemRESUMO
The present study tested the hypothesis that the Janus kinase 2, Src tyrosine kinases, and mitogen-activated protein kinase interact to regulate lordosis behavior induced by leptin in ovariectomized, estrogen-primed rats. The role of protein kinase A and protein kinase C in lordosis facilitation by leptin was also assessed. In experiment 1, the intracerebroventricular administration of leptin to ovariectomized, estradiol-primed rats significantly stimulated lordosis behavior at 1, 2 and 4 h post-injection tests. In experiment 2, the Janus kinase 2 inhibitor AG490, the Src tyrosine kinase inhibitor PP2 and the mitogen-activated protein kinase inhibitor PD98059 were administered into the right lateral ventricle before leptin. The lordosis quotient and the lordosis score induced by leptin were significantly decreased by each of these kinase inhibitors. In experiment 3, we examined the effects of RpcAMPS and bisindolylmaleimide, protein kinase A and protein kinase C inhibitors on the lordosis elicited by leptin administration. Lordosis behavior induced by leptin was significantly decreased by both the protein kinase A and protein kinase C inhibitors at 1 h post-leptin injection. The results confirm that multiple intracellular pathways participate in the expression of lordosis behavior in estrogen-primed rats elicited by leptin.
Assuntos
Dorso/fisiologia , Estrogênios/administração & dosagem , Leptina/fisiologia , Ovariectomia , Proteínas Quinases/metabolismo , Comportamento Sexual Animal , Animais , Feminino , Infusões Intraventriculares , Leptina/administração & dosagem , Ratos , Ratos Sprague-DawleyRESUMO
This study aimed to analyze the electromyographic (EMG) activity of iliocostalis lumborum (IL), internal oblique (IO) and multifidus (MU) and the antagonist cocontraction (IO/MU and IO/IL) during the performance of Centering Principle of Pilates Method. Participating in this study were eighteen young and physically fit volunteers, without experience in Pilates Method, divided in two groups: low back pain group (LBPG, n = 8) and control group (CG, n = 10). Two isometric contractions of IO muscles (Centering Principle) were performed in upright sitting posture. EMG signal amplitude was calculated by Root Mean Square (RMS), which was normalized by RMS maximum value. The common area method to calculate the antagonist cocontraction index was used. MU and IO activation and IO/MU cocontraction (p < 0.05) were higher in CG. The CG therefore showed a higher stabilizer muscles recruitment than LBPG during the performance of Centering Principle of Pilates Method.
Assuntos
Técnicas de Exercício e de Movimento/métodos , Dor Lombar/fisiopatologia , Dor Lombar/terapia , Músculo Esquelético/fisiologia , Tronco/fisiologia , Adolescente , Dorso/fisiologia , Eletromiografia , Feminino , Humanos , Contração Isométrica/fisiologia , Modelos Biológicos , Postura/fisiologia , Adulto JovemRESUMO
The aim of this study was to evaluate how the fixed furniture dimensions match with students' anthropometry and to describe head, upper back and upper limbs postures and movements. Evaluation was performed in 48 students from a Brazilian state school. Furniture dimensions were measured with metric tape, movements and postures by inclinometers (Logger Tecknologi, Åkarp, Sweden). Seat height was high for 21% and low for 36% of the students; seat length was short for 45% and long for 9% and table height was high for 53% and low for 28%. Regression analysis showed that seat/popliteal height quotient is explained by 90th percentile of upper back inclination (ß=0.410) and 90th percentile of right upper arm elevation (ß=-0.293). For seat/thigh length quotient the significant variables were 90th percentile of upper back velocity (ß=-0.282) and 90th percentile of right upper arm elevation (ß=0.410). This study showed a relationship between furniture mismatch and postural overload. When the seat height is low students increase upper back left inclination and right upper arm elevation; when the seat is short students decrease the upper back flexion velocity and increase right upper arm elevation.
Assuntos
Decoração de Interiores e Mobiliário , Movimento , Postura , Adolescente , Antropometria , Dorso/fisiologia , Brasil , Criança , Feminino , Cabeça/fisiologia , Humanos , Masculino , Instituições Acadêmicas , Extremidade Superior/fisiologia , Gravação em VídeoRESUMO
The aim of the current study was to investigate the EMG activity of pectoralis major and latissimus dorsi muscles during the pullover exercise. Eight healthy male volunteers took part in the study. The EMG activity of the pectoralis major and that of the latissimus dorsi of the right side were acquired simultaneously during the pullover exercise with a free-weight barbell during both the concentric and eccentric phases of the movement. After a warm-up, all the subjects were asked to perform the pullover exercise against an external load of 30% of their body weight, during 1 set × 10 repetitions. The criterion adopted to normalize the EMG data was the maximal voluntary isometric activation. The present findings demonstrated that the barbell pullover exercise emphasized the muscle action of the pectoralis major more than that of the latissimus dorsi, and the higher activation depended on the external force lever arm produced.
Assuntos
Dorso/fisiologia , Movimento/fisiologia , Contração Muscular/fisiologia , Músculo Esquelético/fisiologia , Treinamento Resistido/métodos , Tórax/fisiologia , Adulto , Humanos , MasculinoRESUMO
The aim of this work was to reduce ECG artifacts from surface electromyogram (EMG) signals collected from lumbar muscles with the blind source separation technique based on independent component analysis (ICA). Using four EMG signals collected above erector spinal lumbar muscles from 27 subjects, the proposed method fail in separating the sources. However, when considering a single channel of EMG and the same one time-shifted by one sample, the FastICA allowed reducing the signal to ECG noise ratio.