Alex Castro

Utility of electromyographic fatigue threshold during treadmill running

Introduction: We investigated 2 different methods for determining muscle fatigue threshold by electromyography (EMG). Methods: Thirteen subjects completed an incremental treadmill running protocol for EMG fatigue threshold (EMGFT) determination based on the critical power concept (EMGFT1) and the breakpoint in the linear relationship between EMG amplitude and exercise intensity (EMGFT2). Then, both the EMGFT1 and EMGFT2 were tested in a continuous treadmill running protocol. EMG was recorded from the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), and lateral gastrocnemius (LG) muscles. Results: For BF, EMGFT2 was higher than EMGFT1, and EMGFT1 for BF was lower than EMGFT1 for LG. EMG of RF was higher at EMGFT2 than at EMGFT1, and LG EMG was lower at EMGFT2. Conclusions: EMGFT can be determined during a single treadmill running test, and EMGFT1 may be the most appropriate method to estimate the muscle fatigue threshold during running. Muscle Nerve 52: 1030–1039, 2015

Variabilidade de parâmetros eletromiográficos e cinemáticos em diferentes condições de marcha em idosos

The main goal of this study was to investigate the influence of fear of fall and dual task on electromyographic and kinematic variability parameters on the gait of older females. Seventeen college students (21,47 ± 2,06 years old) and eighteen older female adults, both groups were physically fit and performed the gait test on three different conditions: walking at self-select speed, fear of fall and dual task. Electromyographic activity was measured on muscles of dominant leg and stride time was recorded. ANOVA two-way (p<0.05) was used. Electromyographic and kinematic gait variability were higher in older adult groups. However, for the comparison between gait conditions was only found significant difference for electromyographic variability. In line with this, the higher EMG and kinematic variability in older adults suggest that aging contributes for a higher motor challenge while walking, which may be predispose these individuals a higher risk of fall.

Lower limb muscle coactivation levels in healthy younger and older adults during functional dual-task gait

El objetivo de este estudio fue investigar la influencia de una tarea cognitiva diaria en la co-activacion muscular en ancianos y jovenes durante la marcha. Los participantes del estudio fueron 17 ancianos y 18 jovenes fisicamente activos con bajo riesgo de caidas. Los voluntarios caminaron sobre una cinta de correr en dos condiciones diferentes: la marcha normal y la marcha con doble tarea cotidiana. Las electromiografia se obtuvo de los musculos de las extremidades inferiores. El porcentaje de co-activacion de los tibialis anterior/gastrocnemius lateralis and tibialis anterior /soleus fueron significativamente mayores en los ancianos que en los sujetos jovenes durante la marcha normal y marcha con doble tarea. Nuestros resultados sugieren que los ancianos tienen un mayor coactivacion muscular en el tobillo durante la marcha normal y marcha con doble tarea cotidiana. Por lo tanto, se concluye que las situaciones cognitivamente desafiantes durante la marcha puede aumentar el riesgo de caidas en los ancianos.

Metabolomics Approach in the Investigation of Metabolic Changes in Obese Men after 24 Weeks of Combined Training

Obesity is associated with comorbidities related to metabolic disorders due to excess of adipose tissue. Physical exercise has a major role in the prevention of obesity. Combined training (CT), in particular, has been shown to improve markers of health. In this study, we used 1H NMR-based metabolomics to investigate changes in the metabolism of obese men after 24 weeks of CT. Twenty-two obese (body mass index 31 ± 1.4 kg/m2), middle-aged men (48.2 ± 6.1 years) were randomly assigned to a control group (CG, n = 11) or CT group (n = 11). The CT was performed three times a week (resistance and aerobic training) for 24 weeks. Blood samples were collected before and after experimental period. There was an improvement in body composition and physical fitness indices after CT training. Multivariate PCA and PLS-DA models showed a distinct separation between groups. Twenty metabolites with importance for projection (VIP) >1.0 were identified, and four were classified as best discriminators (tyrosine, 2-oxoisocaproate, histidine, pyruvate). Some metabolites were correlated with strength, VO2 peak, fat and lean body mass, waist circumference, and insulin. In conclusion, 24 weeks of CT was effective for functional improvements and metabolic changes in obese middle-aged men.

Hip muscles strength and activation in older fallers and non-fallers

BACKGROUND: Hip muscles dysfunction may challenge postural control mechanisms and compromise the individual in imbalance situations. OBJECTIVE: To compare hip muscles strength, power and activation between older female fallers and non-fallers. METHODS: Forty-four older adult women (60–85 yr) were divided into two groups based on having falling or not in the period of one year before evaluation, fallers (n = 20) and non-fallers (n = 24). Isokinetic strength and power were assessed during hip flexion, extension, abduction and adduction movements, while EMG signals were recorded from the internal oblique (IO), rectus femoris (RF), multifidus (MU), gluteus maximum (GM), and biceps femoris (BF). RESULTS: Fallers had significantly lower extension (p = 0.033), abduction (p = 0.001) and adduction (p = 0.002) strength as well as significantly lower power in hip flexion (p = 0.028), extension (p = 0.005) and abduction (p = 0.002) compared to non-fallers. Non-fallers had 27.4% greater activation of RF (p = 0.005) during hip flexion and 37.9% higher coactivation of IO/MU during hip abduction (p = 0.003). Significant linear regression was found between hip extension strength and GM and BF activation in both groups. CONCLUSION: Hip muscles strength and activation may increase the risk of falling in older women.

ENERGY EXPENDITURE: IS HIGH INTENSITY INTERVAL TRAINING (HIIT) BETTER THAN CONTINUOUS AEROBIC TRAINING?

High Intensity Interval Training (HIIT) has been pointed as an efficient method for cardiorespiratory enhancement in comparison with traditional continuous aerobic training (CAT). Such difference is believed to be explained by assessing the energy expenditure of training sessions. Hence, in order to test this hypothesis, it was realized an acute intervention in recreationally active young men during three experimental conditions with a cross-over design. Energy expenditure results indicate that it is highly correlated with exercise volume, and even though energetic systems contribution during HIIT and CAT sessions were different, total caloric expenditure were similar between exercises sessions.

Análise do COP e sentido de posição em jogadores universitários de futebol com e sem instabilidade de tornozelo

The aim of the study was to compare the behavior of COP and passive ankle position sense in subjects with and without functional ankle instability. Took part in this study 20 subjects, divided into two groups: stable group (SG) and unstable group (UG). The COP evaluation was made with the single-leg balance test, with eyes opened and closed, on a force plate. The passive ankle position sense test was performed with subjects blindfolded. The ankle was positioned in a target angle (10° and 20°) and the dynamometer moved passively the ankle, then the subjects were instructed to push the stop button when they feel that the ankle was on the target angle, obtaining the absolute angular error (AAE). The following variables were obtained: total displacement (TD); antero-posterior (SDap) and medio-lateral standard deviation (SDml); total mean velocity (TMV); antero-posterior (MVap) and medio-lateral mean velocity (MVml). The comparison between the data with normal distribution was made with the Students t test, while to the TD and SDml was used the Mann-Whitney test. The correlations were performed with the Pearson and Spearman tests. We adopted α < 0.05. We observed difference between AAE-10° (p < 0.05). Strong correlations were found between: AAE-10° and TMV (p < 0.01 r = −0.867); AAE-10° and MVap (p < 0.01 r = −0.854); AAE-10° and MVml (p < 0.01 r = −0.771), with eyes opened, and AAE-10° and TD (p < 0.05 r = −0.666); AAE-10° and SDap (p < 0.05 r = −0,685) and AAE-10° and MVml (p < 0.05 r= −0.766) with eyes closed. Ankle sprains harm the joint position sense without affecting the balance.

Coactivación muscular del miembro inferior de jóvenes y ancianos saludables durante la marcha con doble tarea funcional

El objetivo de este estudio fue investigar la influencia de una tarea cognitiva diaria en la co-activacion muscular en ancianos y jovenes durante la marcha. Los participantes del estudio fueron 17 ancianos y 18 jovenes fisicamente activos con bajo riesgo de caidas. Los voluntarios caminaron sobre una cinta de correr en dos condiciones diferentes: la marcha normal y la marcha con doble tarea cotidiana. Las electromiografia se obtuvo de los musculos de las extremidades inferiores. El porcentaje de co-activacion de los tibialis anterior/gastrocnemius lateralis and tibialis anterior /soleus fueron significativamente mayores en los ancianos que en los sujetos jovenes durante la marcha normal y marcha con doble tarea. Nuestros resultados sugieren que los ancianos tienen un mayor coactivacion muscular en el tobillo durante la marcha normal y marcha con doble tarea cotidiana. Por lo tanto, se concluye que las situaciones cognitivamente desafiantes durante la marcha puede aumentar el riesgo de caidas en los ancianos.

Coativação muscular dos membros inferiores de jovens e idosas saudáveis durante marcha com dupla tarefa funcional

El objetivo de este estudio fue investigar la influencia de una tarea cognitiva diaria en la co-activacion muscular en ancianos y jovenes durante la marcha. Los participantes del estudio fueron 17 ancianos y 18 jovenes fisicamente activos con bajo riesgo de caidas. Los voluntarios caminaron sobre una cinta de correr en dos condiciones diferentes: la marcha normal y la marcha con doble tarea cotidiana. Las electromiografia se obtuvo de los musculos de las extremidades inferiores. El porcentaje de co-activacion de los tibialis anterior/gastrocnemius lateralis and tibialis anterior /soleus fueron significativamente mayores en los ancianos que en los sujetos jovenes durante la marcha normal y marcha con doble tarea. Nuestros resultados sugieren que los ancianos tienen un mayor coactivacion muscular en el tobillo durante la marcha normal y marcha con doble tarea cotidiana. Por lo tanto, se concluye que las situaciones cognitivamente desafiantes durante la marcha puede aumentar el riesgo de caidas en los ancianos.