Camilla Zamfolini Hallal

Association between energy cost of walking, muscle activation, and biomechanical parameters in older female fallers and non-fallers

OBJECTIVE To determine the nervous activation, muscle strength, and biomechanical parameters that influence the cost of walking in older fallers and non-fallers. METHODS Maximal voluntary isokinetic torque was measured for the hip, knee and ankle of older women. Oxygen consumption was measured at rest and during 8min of walking at self-selected speed. An additional minute of walking was performed to collect kinematic variables and the electromyographic signal of trunk, hip, knee, and ankle muscles, which was analyzed by the linear envelope. Cost of walking was calculated by subtracting resting body mass-normalized oxygen consumption from walking body mass-normalized oxygen consumption. Stride time and length, and ankle and hip range of motion were calculated from kinematic data. FINDINGS Older adult fallers had 28% lower knee extensor strength (p=0.02), 47% lower internal oblique activation at heel contact (p=0.03), and higher coactivation between tibialis anterior and gastrocnemius lateralis in each of the gait phases (p<0.05). For fallers, a higher activation of gluteus maximus was associated with a higher cost of walking (r=0.55, p<0.05 and r=0.71, p<0.01, before and after heel contact, respectively). For non-fallers, an association between cost of walking and age (r=0.60, p=0.01) and cost of walking and thigh muscle coactivation (r=0.53, p=0.01) existed. INTERPRETATION This study demonstrated that there may be links between lower-extremity muscle weakness, muscle activation patterns, altered gait, and increased cost of walking in older fallers.

Motor readiness and joint torque production in lower limbs of older women fallers and non-fallers

This study aimed to evaluate the motor response time and ability to develop joint torque at the knee and ankle in older women with and without a history of falls, in addition to investigating the effect of aging on these capacities. We assessed 18 young females, 21 older female fallers and 22 older female non-fallers. The peak torque, rate of torque development, rate of electromyography (EMG) rise, reaction time, premotor time and motor time were obtained through a dynamometric assessment and simultaneous electromyography. Surface EMGs of the rectus femoris (RF), vastus lateralis (VL), biceps femoris (BF), gastrocnemius lateralis (GL) and tibialis anterior (TA) muscles were recorded. Knee extension and flexion peak torques were lower in older fallers than in non-fallers. Knee extension and flexion and ankle plantarflexion and dorsiflexion peak torques were lower in both older groups than in the younger group. The rate of EMG rise of the BF and the motor time of the TA were lower and higher, respectively, in older fallers than in the younger adults. The time to reach peak torque in knee extension/flexion and ankle plantarflexion/dorsiflexion and the motor times of the RF, VL, BF and GL were higher in both older groups than in the younger groups. The motor time of the TA during ankle dorsiflexion and the knee extension peak torque were the major predictors of falls in older women, accounting for approximately 28% of the number of falls. Thus, these results further reveal the biomechanical parameters that affect the risk of falls and provide initial findings to support the prescription of exercises in fall prevention programs.

Electromyographic activity of trunk muscles during exercises with flexible and non-flexible poles

OBJECTIVE Hand-held flexible poles which are brought into oscillation to cause alternating forces on trunk, are advocated as training devices that are supposed to solicit increased levels of stabilizing trunk muscle activity. The aim of this study was to verify this claim by comparing electromyographic (EMG) activity of trunk muscles during exercises performed with a flexible pole and a rigid pole. METHODS Twelve healthy females performed three different exercises with flexible and rigid poles. EMG activity of iliocostalis lumborum (IL), multifidus (MU), rectus abdominis (RA), external oblique (EO) and internal oblique (IO), and was continuously measured. The EMG signals were analyzed in time domain by calculation of the Root Mean Square (RMS) amplitudes over 250 ms windows. The mean RMS-values over time were normalized by the maximum RMS obtained for each muscle. RESULTS The IO showed a 72% greater EMG activity during the exercises performed with the flexible pole than with the rigid pole (p=0.035). In exercises performed in standing, the IO was significantly more active than when sitting (p=0.006). CONCLUSION As intended, the cyclic forces induced by the oscillating pole did increase trunk muscle activation. However, the effect was limited and significant for the IO muscle only.

Antagonist coactivation of trunk stabilizer muscles during Pilates exercises

The purpose of this study was to compare the antagonist coactivation of the local and global trunk muscles during mat-based exercises of Skilled Modern Pilates. Twelve women performed five exercises and concurrently, surface EMG from internal oblique (OI), multifidus (MU), rectus abdominis (RA) and iliocostalis lumborum (IL) muscles was recorded bilaterally. The percentage of antagonist coactivation between local (OI/MU) and global muscles (RA/IL) was calculated. Individuals new to the practice of these exercises showed differences in coactivation of the trunk muscles between the exercises and these results were not similar bilaterally. Thus, in clinical practice, the therapist should be aware of factors such as compensation and undesirable rotation movements of the trunk. Moreover, the coactivation of global muscles was higher bilaterally in all exercises analyzed. This suggests that the exercises of Skilled Modern Pilates only should be performed after appropriate learning and correct execution of all principles, mainly the Centering Principle.

EMG activity of trunk stabilizer muscles during Centering Principle of Pilates Method

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.

Características biomecânicas, ergonômicas e clínicas da postura sentada: uma revisão

The sitting posture is the most adopted in work environment, at school and in leisure activities. However, prolonged maintenance of this position causes the adoption of inadequate postures and overloads skeletal muscle structures, which may lead to spine pain and injuries. The purpose of the present review was to identify biomechanic, ergonomic, and clinical features involved in maintenance of the sitting position. The search in ISI Web of Knowledge, Medline, Pubmed and EBSCOHost data bases led to selecting 72 articles published between 1965 and 2010. Results show that there is not an ideal posture to be kept, but some postures are more recommended than others, like the upright sitting and the lordotic postures. Chairs influence the pattern of sitting, and their design allows for posture diversity. Changes in the chair, exercises to improve endurance and proprioception, as well as postural re-education, are useful interventions to reduce the impact of prolonged sitting position on the skeletal muscle system.

Electromyographic patterns of lower limb muscles during apprehensive gait in younger and older female adults.

OBJECTIVE Investigate the influence of apprehensive gait on activation and cocontraction of lower limb muscles of younger and older female adults. METHODS Data of 17 younger (21.47±2.06yr) and 18 older women (65.33±3.14yr) were considered for this study. Participants walked on the treadmill at two different conditions: normal gait and apprehensive gait. The surface electromyographic signals (EMG) were recorded during both conditions on: rectus femoris (RF), vastus lateralis (VL), vastus medialis (VM), biceps femoris (BF), tibialis anterior (TA), gastrocnemius lateralis (GL), and soleus (SO). RESULTS Apprehensive gait promoted greater activation of thigh muscles than normal gait (F=5.34 and p=0.007, for significant main effect of condition; RF, p=0.002; VM, p<0.001; VL, p=0.003; and BF, p=0.001). Older adults had greater cocontraction of knee and ankle stabilizer muscles than younger women (F=4.05 and p=0.019, for significant main effect of groups; VM/BF, p=0.010; TA/GL, p=0.007; and TA/SO, p=0.002). CONCLUSION Apprehensive gait promoted greater activation of thigh muscles and older adults had greater cocontraction of knee and ankle stabilizer muscles. Thus, apprehensive gait may leads to increased percentage of neuromuscular capacity, which is associated with greater cocontraction and contribute to the onset of fatigue and increased risk of falling in older people.

Electromyographic activity of shoulder muscles during exercises performed with oscillatory and non-oscillatory poles

BACKGROUND Pain and dysfunction of the shoulder complex are commonly found physiotherapy practice. These musculoskeletal abnormalities are related to instability and inadequate kinematic function, that depend on the integrity of the muscle tissues. Thus, to enhance the results of exercise therapies, and prevent and attenuate pain and dynfunction, the use of oscillatory pole has been implemented in clinical practice. OBJECTIVES The purpose of this study was to analyze the electromyographic (EMG) activity of shoulder stabilizing muscles during exercises performed with an oscillatory and a non-oscillatory pole. METHODS Twelve female volunteers, aged 20.4 years±1.9, participated in this study. EMG data were collected from upper trapezius (UT), lower trapezius (LT) and middle deltoid (MD) during three different exercises with an oscillatory and a non-oscillatory pole. The EMG signals were analyzed in the time domain through the calculation of Root Mean Square (RMS). The RMS values were normalized by the peak value obtained over all trials for each muscle. Statistical analysis was performed with repeated measures ANOVA and post-hoc of Bonferroni tests. RESULTS The EMG activity of UT, LT and MD muscles were significantly higher with the oscillatory pole than the non-oscillatory pole (all p<0,001). There were no significant differences in the activation of these muscles between exercises. CONCLUSION The results of the present study indicated that the oscillatory pole does require higher activation of the shoulder muscles and therefore, may be useful in the training of the shoulder complex.

Padrão de co-ativação dos músculos do tronco durante exercícios com haste oscilatória

Univ Estadual Paulista, UNESP, Lab Biomecan, Dept Educ Fis,Inst Biociencias, BR-13506900 Rio Claro, SP, Brazil

Razão eletromiográfica de músculos estabilizadores do ombro durante a execução de exercícios com haste oscilatória

Os processos de dor e disfuncao do ombro sao muito comuns e demandam grande atencao por parte dos profissionais que treinam e reabilitam esta articulacao. O excesso de ativacao do musculo trapezio superior (TS) combinado com a diminuicao da ativacao do trapezio inferior (TI) tem sido proposto como fator contribuinte para lesoes no ombro. Diversos equipamentos sao usados no treinamento e reabilitacao destes musculos como faixas elasticas, cargas livres e, recentemente, hastes oscilatorias. Apesar de muito utilizada no contexto clinico e desportivo, pouco se sabe acerca dos efeitos destas hastes sobre o recrutamento dos musculos estabilizadores de ombro. Assim, o objetivo do presente estudo foi determinar a razao de ativacao entre os musculos TS e TI em diferentes exercicios realizados com haste oscilatoria. Participaram do estudo 12 individuos do sexo feminino, jovens (20,4 ± 2,0 anos), fisicamente ativas. O sinal eletromiografico dos musculos TS e TI foi coletado durante a execucao de tres diferentes exercicios realizados com a haste oscilatoria. A analise dos dados eletromiograficos foi feita a partir dos valores de root mean square (RMS) pelo calculo da razao entre os musculos TS e TI para cada exercicio. Para analise estatistica foram utilizados os testes ANOVA para medidas repetidas e post hoc de Bonferroni, considerando como nivel de significância p < 0,05. O exercicio III apresentou menor razao entre os musculos TS e TI (0,722), seguido pelos exercicios I e II, respectivamente (0,876 e 0,995). CONCLUSAO: O uso da haste oscilatoria em exercicios executados unimanualmente no plano sagital e com a haste perpendicular ao solo sao recomendados para o treinamento e reabilitacao dos musculos estabilizadores da escapula por promoverem menor ativacao do TS em relacao o TI