Effects of a 12-week hip abduction exercise program on the electromyographic activity of hip and knee muscles of women with patellofemoral pain: A pilot study

Aims: The purpose of our study was to compare the hip and knee muscle activity before and after a hip abduction exercise program in women with patellofemoral pain (PFP). Methods: Eleven women with PFP were included in our pre/post design study. Participants were assessed before and after 12-week hip abduction exercise program. All participants performed 6 stair climbing repetitions, 3 sets of rope jumps over 30 s and 5 sets of 8 squats to standardize the physical activity level before data collection. We recorded the electromyographic activity from gluteus medius, vastus medialis (VM) and vastus lateralis (VL) for double-legged squat with and without isometric hip abduction. Additionally, participants were asked to perform a step-down test to assess objective function (maximum number of repetitions over 30 s) and completed a clinical evaluation. Results: Longer duration of VM (Mean difference [95% CI]) = -0.97 [-1.48; -0.46], ES [effect size] = 0.66) and VL (-0.81 [-1.35; -0.27], ES = 0.54) were found after the hip abduction exercise program only for free squat. The participants also performed higher number of step-down repetitions (-3.54 [-5.84; -1.25], ES = 1.03) after the hip abduction exercise program and showed improvement in pain reports. Conclusion: A 12-week hip abduction exercise program changed the quadriceps muscle activation pattern and improved pain and objective function of women with PFP. The exercises promoted a longer VM and VL activation duration. Additionally, they promoted a clinical improvement in the patients with PFP.(AU)

Efeito agudo de saltos intermitentes na arquitetura muscular do Vasto Lateral em atletas de voleibol / Acute effect of intermittent jumps on the Vastus Lateralis muscle architecture in volleyball players

O aumento do ângulo de penação de fibras musculares durante contração causa uma redução da geração de força do músculo. O objetivo deste estudo foi verificar a relação entre o ângulo de penação do músculo Vasto lateral (VL) com o rendimento em um teste de saltos verticais intermitentes. Foi testado um grupo de 18 atletas do sexo masculino da Confederação Brasileira de voleibol do Exército Brasileiro. Duas imagens longitudinais do VL, a 50% do comprimento da coxa, foram adquiridas com um Ultrassom modo-B. Posteriormente, os indivíduos realizaram um teste único do tipo Counter Movement Jump para avaliar a altura máxima do salto vertical. A tarefa de saltos verticais intermitentes compreendeu quatro séries de 15 segundos de saltos máximos. Imediatamente após a tarefa, duas imagens do ângulo de penação foram novamente adquiridas na mesma região. Duas medidas do ângulo de penação foram feitas em cada imagem, totalizando oito medições por indivíduo. Os resultados mostraram que houve redução significativa da altura dos saltos no decorrer da tarefa (35,77 ± 4,67 cm; 31,94 ± 4,51 cm; 27,04 ± 3,93 cm e 22,60 ± 3,66 cm para os intervalos de 0-15 s, 15-30 s, 30-45 s e 45-60 s, respectivamente). O ângulo de penação do VL não apresentou diferença significativa antes e após a realização da tarefa (12,72 ± 2,26º e 13,71 ± 3,40º, respectivamente). A correlação de Pearson entre as medidas do ângulo de penação no pré e pós teste intermitente e entre as alturas em todos os intervalos foram fracas (0,034

Increased pennation angle of the muscle fibers during contraction causes a reduced muscle force generation. The aim of this study was to investigate the relationship between the pennation angle of the vastus lateralis muscle (VL) with the performance of an intermittent vertical jumps test. We tested a group of 18 male athletes of the Brazilian Army Confederation of Volleyball. Two longitudinal images of the VL, at 50% of thigh length were acquired with a B-mode ultrasound. Soon after, subjects performed a Counter Movement Jump test to evaluate the maximum vertical jump height. The intermittent vertical jumps test comprised four sets of 15 s maximum jumps. Immediately after, the two images of the pennation angle were again obtained in the same region. Two pennation angle measurements were made in each image, totaling eight measurements per individual. The results of this study showed that there was a significant reduction of the jumps heights (35.77 ± 4.67 cm; 31.94 ± 4.51 cm; 27.04 ± 3.93 cm and 22.60 ± 3 66 cm intervals for 0-15 s, 15-30 s, 30-45 s and 45-60 s, respectively). The VL pennation angle did not present a significant difference before and after the test (12.72 ± 2.26 ° and 13.71 ± 3.40º respectively). The Pearson correlation between the pennation angle measurements before and after the intermittent test and among the heights in all intervals were weak (0.034