Jake do Carmo

EFFECTS OF EXERCISE ORDER ON UPPER-BODY MUSCLE ACTIVATION AND EXERCISE PERFORMANCE

With the purpose of manipulating training stimuli, several techniques have been employed to resistance training. Two of the most popular techniques are the pre-exhaustion (PRE) and priority system (PS). PRE involves exercising the same muscle or muscle group to the point of muscular failure using a single-joint exercise immediately before a multi-joint exercise (e.g., peck-deck followed by chest press). On the other hand, it is often recommended that the complex exercises should be performed first in a training session (i.e., chest press before peck-deck), a technique known as PS. The purpose of the present study was to compare upper-body muscle activation, total repetitions (TR), and total work (TW) during PRE and PS. Thirteen men (age 25.08 = 2.58 years) with recreational weight-training experience performed 1 set of PRE and 1 set of PS in a balanced crossover design. The exercises were performed at the load obtained in a 10 repetition maximum (10RM) test. Therefore, chest press and peck-deck were performed with the same load during PRE and PS. Electromyography (EMG) was recorded from the triceps brachii (TB), anterior deltoids, and pectoralis major during both exercises. According to the results, TW and TR were not significantly different (p ≥ 0.05) between PRE and PS. Likewise, during the peck-deck exercise, no significant (p ≥ 0.05) EMG change was observed between PRE and PS order. However, TB activity was significantly (p ≤ 0.05) higher when chest press was performed after the peck-deck exercise (PRE). Our findings suggest that performing pre-exhaustion exercise is no more effective in increasing the activation of the prefatigued muscles during the multi-joint exercise. Also, independent of the exercise order (PRE vs. PS), TW is similar when performing exercises for the same muscle group. In summary, if the coach wants to maximize the athlete performance in 1 specific resistance exercise, this exercise should be placed at the beginning of the training session.

Compression of EMG signals with wavelet transform and artificial neural networks

This paper presents a hybrid adaptive algorithm for the compression of surface electromyographic (S-EMG) signals recorded during isometric and/or isotonic contractions. This technique is useful for minimizing data storage and transmission requirements for applications where multiple channels with high bandwidth data are digitized, such as telemedicine applications. The compression algorithm proposed in this work uses a discrete wavelet transform for spectral decomposition and an intelligent dynamic bit allocation scheme implemented by an approach using the Kohonen layer, which improves the bit allocation for sections of the S-EMG with different characteristics. Finally, data and overhead information are packed by entropy coding. The results for the compression of isometric EMG signals showed that this algorithm has a better performance than standard wavelet compression algorithms presented in the literature (presenting a decrease of at least 5% in per cent residual difference (PRD) for the same compression ratio), and a performance that is comparable with the performance of algorithms based on an embedded zero-tree wavelet. For isotonic EMG signals, its performance is better than the performance of the algorithms based on embedded zero-tree wavelets (presenting a decrease in PRD of about 3.6% for the same compression ratios, in the useful compression range).

Does whole-body cryotherapy improve vertical jump recovery following a high-intensity exercise bout?

Whole-body cryotherapy (WBC) has been used as a recovery strategy following different sports activities. Thus, the aim of the study reported here was to examine the effect of WBC on vertical jump recovery following a high-intensity exercise (HIE) bout. Twelve trained men (mean ± standard deviation age = 23.9±5.9 years) were randomly exposed to two different conditions separated by 7 days: 1) WBC (3 minutes of WBC at −110°C immediately after the HIE) and 2) control (CON; no WBC after the HIE). The HIE consisted of six sets of ten repetitions of knee extensions at 60° · s−1 concentric and 180° · s−1 eccentric on an isokinetic dynamometer. The vertical jump test was used to evaluate the influence of HIE on lower extremity muscular performance. The vertical jump was performed on a force platform before HIE (T1) and 30 minutes after (T2) the WBC and CON conditions. As a result of HIE, jump height, muscle power, and maximal velocity (Vmax) had significant decreases between T1 and T2, however no significance was found between the WBC and CON conditions. The results indicate that one session of WBC had no effect on vertical jump following an HIE compared with a CON condition. WBC may not improve muscle-function (dependent on stretch-shortening cycle) recovery in very short periods (ie, 30 minutes) following HIE.

Comparação entre a atividade EMG do peitoral maior, deltóide anterior e tríceps braquial durante os exercícios supino reto e crucifixo

The identification of the characteristics of each movement and its adjustment to the training goals are tasks that demand the interaction of many knowledge areas. These tasks are essential to the success in sports activities and training programs designed with athletic, aesthetic or healthy purposes. The objective of the present study was to compare the electromyographic (EMG) activity of the pectoralis major (PM), anterior deltoids (DA) and triceps brachii (TB) muscles during the barbell bench press (SP) and the peck deck (PD) exercises. EMG activity of TB, PM and DA were assessed during 10 maximum repetitions performed in SP and PD in 13 trained men. The results did not show any differences between exercises for PM and DA activity; however, TB activity was higher for SP than PD exercise. During SP, the PM muscle activity was higher than TB. There were no differences between PM and DA, or between DA and TB. During the PD exercise, the PM and DA muscle activities were higher than TB. There were no differences between PM and DA. It was concluded that the prime movers of both exercise are DA and PM, and there are no differences between them. Therefore, both PD and SP could be performed with the purpose to stimulate DA and PM muscles, depending on the availability of the equipments and/or the specificity of the motor tasks.La identificacion de las peculiaridades de cada movimiento y su adecuacion a los objetivos de entrenamiento es una tarea que exige la interaccion de varias areas de conocimiento. Tal tarea es fundamental para el exito en las diversas modalidades deportivas y programas de entrenamiento con fines de rehabilitacion y/o estetica. El objetivo del presente estudio ha sido comparar la actividad electromiografica (EMG) de los musculos pectoral mayor (PM), deltoides anterior (DA) y triceps braquial (TB) durante la ejecucion de los ejercicios supino recto con barra (SP) y de cruz en maquina (CR). Las actividades EMG de los musculos PM, DA y TB fueron evaluados durante la realizacion de 10 repeticiones maximas en CR y SP en 13 hombres entrenados. Los resultados no revelaron diferencias en la actividad de PM y DA entre los ejercicios. La actividad de TB fue mayor en la realizacion de SP en comparacion con CR. Durante SP, la actividad de PM fue mayor en relacion a TB, sin diferencias entre PM y DA o DA y TB. En CR, la actividad de PM y DA fueron mayores en relacion a TB, sin diferencias entre DA y PM. De acuerdo con los resultados obtenidos en el presente estudio se puede concluir que en caso de que el objetivo de entrenamiento sea promover estimulos para DA o PM, ambos ejercicios pueden ser usados, dependiendo de la disponibilidad de materiales y/o de la especificidad de la actividad motora en la cual se procure mejorar el desempeno.

Prolonged use of Kinesiotaping does not enhance functional performance and joint proprioception in healthy young males: Randomized controlled trial.

ABSTRACT Objectives The aim of this study was to investigate the effects of continuous (48-hour) use of Kinesiotaping (KT) on functional and proprioceptive performance in healthy, physically active men. Method Twenty-six healthy, physically active men (21.8±2.2 years old) were randomly allocated into two groups: 1) Kinesiotaping group (KG, tape applied with 40% tension for rectus femoris activation); 2) Control (CG, tape applied over rectus femoris without additional tension). Subjects attended the laboratory on five separate occasions: 1) familiarization; 2) baseline measurement without tape (BL); 3) immediately post-tape application (T0); 4) 24h (T24); and 5) 48h (T48) post-tape application. The outcomes were distance in the single (SHT) and triple hop tests (THT), vertical jump height (VJH), vertical jump power (VJP), and rate of force development (RFD). A mixed-model ANOVA was applied to verify differences between and within groups. Results No significant (p >0.05) differences were found in the SHT and THT between groups and moments. Likewise, the main effects for VJH, VJP, and RFD were not significant (p >0.05). Conclusion The present study demonstrated no significant immediate or prolonged (48h) effects of KT on functional and proprioceptive performance.

The Effects of Graduated Compression Sleeves on Muscle Performance: A Randomised Controlled Trial

The purpose of this study was to examine the effects of graduated compression sleeves on muscle performance during high-intensity exercise. Twenty-four resistance trained men were randomly assigned to one of two groups: compression sleeve (GCS, n=11) or placebo sleeve (GPS, n=13). Participants performed 4 sets of 10 unilateral maximal eccentric/concentric elbow flexion repetitions on an isokinetic dynamometer at 120°s−1 with 1 min of inter-set rest. Average torque, work and power were measured during concentric and eccentric actions. ANOVA revealed no significant interactions or main effects for group for any variable. However, values decreased significantly across sets for average torque (1st = 46.55 ± 11.11 Nm to 4th = 36.75 ± 8.78 Nm), average work (1st = 78.83 ± 18.49 J to 4th = 53.26 ± 10.04 J) and average power (1st = 52.3 ± 12.03 W to 4th = 32.59 ± 8.82 W). Therefore, the use of a graduated compression sleeve appears not enhance isokinetic elbow flexion muscle performance.

Reliability of normalized surface electromyographic signals of maximal upper-body isokinetic strength

BACKGROUND: Normalization in surface electromyography (SEMG) has been the object of numerous investigations. OBJECTIVE: The purpose of this study was to evaluate the reliability of normalized SEMG amplitude, as well as the reliability of different normalization coefficients during isokinetic upper-body strength assessment. METHODS: Thirteen male subjects performed a maximal isokinetic elbow flexion test and test-retest separated by 5 to 7 days. Three normalization coefficients were extracted from the tests: 1) mean value of the rectified SEMG signal (MeanTask); 2) peak value of the rectified SEMG signal (PeakTask); 3) maximal value of the rectified SEMG signal of the peak torque repetition (Isokinetic-specMVC). These normalization coefficients, as well as the root mean square value (RMS) of the signal before and after normalization by described coefficients (RMS-MeanTask; RMS-PeakTask; RMS-Isokinetic-specMVC) were evaluated in terms of absolute and relative reliability. RESULTS: None of the normalization coefficients presented acceptable levels of absolute reliability (bias range in limits of agreement greater than 27%). However MeanTask and Isokinetic-specMVC presented good levels of relative reliability (ICC > 0.80). RMS-MeanTask was the only amplitude parameter that demonstrated satisfactory indices of absolute (bias range lower than 5% and CV 0.80) reliability. CONCLUSIONS: Normalizing SEMG amplitude by MeanTask is a reasonable strategy to reduce day-to-day amplitude discrepancies during isokinetic upper-body strength assessment.

The effects of Kinesiotaping on quadriceps muscle performance at different velocities : A randomized controlled trial

BACKGROUND: Kinesiotaping (KT) has become popular among athletic trainers and physical therapists. Most of KT studies investigated only the immediate responses, and only a few evaluated the long-term effects. OBJECTIVES: To evaluate the effects of 48 hours of KT on knee extensor performance of healthy subjects during isokinetic exercise at different muscle action velocities. METHODS: Twenty six healthy men were enrolled and the study presented a drop-out rate of 19%. Participants were randomly allocated to one of two intervention groups: 1. KT with the tape applied for activation of rectus femoris with 40% tension 2. Control (CO) with the tape applied on rectus femoris without tension. Measurements were collected at baseline (BL) without KT, immediately (T0) post KT application, and 24 h (T24) and 48 h (T48) after KT application. The main outcome measures were Knee extension peak torque (PT), load range (LR) and time to reach the PT (TPT). RESULTS: There were no significant differences between KT and CO for PT, LR or TPT at 60 or 240°/s, and no significant differences on time (BL, IMD, 24 h and 48 h) for both groups. CONCLUSION: Kinesiotaping did not enhance knee extensor neuromuscular performance of healthy men at different muscle action velocities. An important finding was that the continued use of the Kinesiotaping (48 h) did not influence muscle performance.

Parâmetros eletromiográficos em exercícios fatigantes realizados com diferentes tipos de resistência

En esta investigacion se pretendio estudiar los estandares electromiograficos de fatiga muscular durante la realizacion de ejercicio dinamico con resistencia variable (elastico) y resistencia fija (polea). Han participado voluntariamente diez varones entrenados. Se llevo a cabo dos contracciones voluntarias maximas (CVIM) de flexion de codo, cada cual de cinco segundos de duracion y dos minutos de intervalo entre las mismas. Despues los voluntarios hicieron la flexion unilateral del codo hasta sentirse cansados, y emplearon la resistencia fija y elastica con ritmo prestablecido de dos segundos para cada fase del movimiento. Se llevo a cabo la resistencia constante en la polea a 30% de la CVIM. Relativo a la resistencia elastica, el control de carga se basaba en una percepcion subjetiva del esfuerzo empleado por el participante. El orden del ejercicio fue aleatorio, y se registro la senal electromiografica del musculo biceps durante las contracciones. Desde la senal electromiografica relativa a cada ejecucion del movimiento se dibujo rectas de regresion lineal para las variables RMS y la frecuencia de potencia media (FPM). Se confirmo las inclinaciones de rectas normalizadas por el coeficiente lineal de las ecuaciones de regresion a traves de la prueba t pareada. No se observaron diferencias significantes entre los tipos de resistencia (elastica y polea). Los estandares electromiograficas de fatiga durante la practica de ejercicios de flexion de codo empleando resistencia elastica y polea no fueron distintos. La percepcion del esfuerzo durante la practica de ejercicio con elastico no trae consecuencias al estandar de senal electromiografico (RMS y FPM).

Estándares electromiográficos en ejercicios extenuantes empleando distintos tipos de resistencia

En esta investigacion se pretendio estudiar los estandares electromiograficos de fatiga muscular durante la realizacion de ejercicio dinamico con resistencia variable (elastico) y resistencia fija (polea). Han participado voluntariamente diez varones entrenados. Se llevo a cabo dos contracciones voluntarias maximas (CVIM) de flexion de codo, cada cual de cinco segundos de duracion y dos minutos de intervalo entre las mismas. Despues los voluntarios hicieron la flexion unilateral del codo hasta sentirse cansados, y emplearon la resistencia fija y elastica con ritmo prestablecido de dos segundos para cada fase del movimiento. Se llevo a cabo la resistencia constante en la polea a 30% de la CVIM. Relativo a la resistencia elastica, el control de carga se basaba en una percepcion subjetiva del esfuerzo empleado por el participante. El orden del ejercicio fue aleatorio, y se registro la senal electromiografica del musculo biceps durante las contracciones. Desde la senal electromiografica relativa a cada ejecucion del movimiento se dibujo rectas de regresion lineal para las variables RMS y la frecuencia de potencia media (FPM). Se confirmo las inclinaciones de rectas normalizadas por el coeficiente lineal de las ecuaciones de regresion a traves de la prueba t pareada. No se observaron diferencias significantes entre los tipos de resistencia (elastica y polea). Los estandares electromiograficas de fatiga durante la practica de ejercicios de flexion de codo empleando resistencia elastica y polea no fueron distintos. La percepcion del esfuerzo durante la practica de ejercicio con elastico no trae consecuencias al estandar de senal electromiografico (RMS y FPM).