Effectiveness of Iliopsoas Self-Stretching on Hip Extension Angle, Gluteus Maximus Activity, and Pelvic Compensations during Prone Hip Extension in Subjects with Iliopsoas Shortness

PURPOSE: This study examined the effectiveness of iliopsoas self-stretching on the hip extension angle, gluteus maximus (GM) activity, and pelvic compensated angle during prone hip extension (PHE) in subjects with iliopsoas shortness. METHODS: Twenty-healthy subjects with iliopsoas shortness were recruited. Electromyography (EMG) was used to examine erector spinae (ES), multifidus (MF), GM, and biceps femoris (BF) while performing PHE. An electromagnetic tracking motion analysis device was used to measure the pelvic compensations. The pelvic compensations while performing PHE were considered to be anterior tilting and rotation. A modified Thomas test was used to monitor the hip extension angle before and after iliopsoas self-stretching. A paired t-test was used to investigate the significant difference after iliopsoas self-stretching during PHE. The level of statistical significance was set to α=0.05. RESULTS: Muscle activity of GM and hip extension angle were significantly greater after iliopsoas self-stretching compared to that before iliopsoas self-stretching during PHE (p 0.05). CONCLUSION: Iliopsoas self-stretching can be effective in selectively strengthening the GM muscles with minimized pelvic compensation in subjects with iliopsoas shortness.

Effect of knee flexion angles during maximum isometric hip extension / 体力科学

The purpose of this study was to examine the effects of knee flexion angles during maximum isometric hip extension. Ten healthy men performed maximum isometric hip extension in prone position at 15° and 90° knee flexion. Then, the hip extension torque was measured, and electromyographic (EMG) data were obtained from the biceps femoris long head, semitendinosus, semimembranosus, adductor magnus, and gluteus maximus muscles. The EMG data were full-wave rectified and integrated (IEMG). The IEMG values obtained during the measurement of isometric hip extension were normalized with the values collected at 90° knee flexion (normalized IEMG [NIEMG]). The hip extension torque at 15° knee flexion was significantly greater than that at 90° knee flexion. The NIEMG values from the hamstrings at 15° knee flexion significantly increased compared with those at 90° knee flexion. Meanwhile, the NIEMG values from the gluteus maximus at 90° knee flexion were significantly greater than those at 15° knee flexion. However, the NIEMG values from the adductor magnus did not significantly differ between 15° and 90° knee flexion. These results indicate that the hamstrings effectively generate contracting force during isometric hip extension and at knee extended position because its fiber length was close to the optimal length.

Comparison of different hamstrings training effect on hamstrings:quadriceps strength ratios / 体力科学

Hamstring muscles form a multi-articular muscle group that crosses the hip and knee joints. It has been said that the imbalance in the hamstrings:quadriceps strength ratio (H:Q ratio) due to weaker hamstring muscles results in an increased susceptibility to hamstring strains and anterior cruciate ligament injuries. Four different hamstrings trainings, Hip Lift (HL), Single-leg Deadlift (DL), Leg Curl (LC), and Nordic Hamstrings (NH), were conducted and compared in the effect on conventional H:Q ratio. After the training of two months, significant increase of hip extension torque and H:Q ratios in the hip joint were found in the DL group, and significant increase of knee flexion torque and H:Q ratios in the knee joint were found in the LC group (<i>P</i> < 0.05). As a conclusion, DL and LC training could be practical for hamstrings injury prevention.

Análise do torque de resistência e da força muscular resultante durante exercício de extensão de quadril no Pilates e suas implicações na prescrição e progressão / Assessment of resistance torque and resultant muscular force during Pilates hip extension exercise and its implications to prescription and progression

CONTEXTUALIZAÇÃO: A análise da mecânica externa dos exercícios de Pilates e da biomecânica das articulações pode subsidiar a prescrição de exercícios na reabilitação. OBJETIVOS: Avaliar o comportamento do torque de resistência (ΓR) do exercício de extensão de quadril (EQ) realizado no Cadillac; realizar uma análise biomecânica a partir do comportamento do ΓR e das distâncias perpendiculares médias ponderadas (DPMPs) para estimar a força muscular resultante (FM R) dos extensores e flexores e propor critérios mecânicos para progressão do exercício de EQ realizado no Cadillac. MÉTODOS: Catorze praticantes de Pilates realizaram EQ no aparelho Cadillac em quatro situações em ordem aleatorizada - usando duas molas (vermelha e azul) fixadas em duas posições (alta e baixa). As posições angulares foram coletadas por meio de eletrogoniometria. Para o cálculo do ΓR, torque muscular (ΓM) e da FM R foram usados diagramas de corpo livre e equações de movimento. Os valores de DPMP dos músculos flexores e extensores do quadril foram quantificados usando dados da literatura. RESULTADOS: O ΓR e a FM R apresentaram comportamentos semelhantes em todas as situações, entretanto os valores máximos de ΓR não ocorrem na mesma posição articular que a FM R máxima. A DPMP dos flexores de quadril apresentou um comportamento crescente-decrescente, com máximo próximo aos 55º de flexão, enquanto os extensores de quadril apresentaram comportamento semelhante, com máximo próximo aos 25º de flexão. CONCLUSÃO: A análise biomecânica do exercício e a avaliação das características mecânicas associadas à articulação do quadril podem ser usadas como critérios objetivos de prescrição e progressão do exercício de EQ no Pilates.

BACKGROUND: The understanding of the external mechanics of Pilates exercises and the biomechanics of the joints may guide the prescription of rehabilitation exercises. OBJECTIVES: To evaluate the resistance torque (ΓR) during hip extension (HE) exercises performed on the Pilates Cadillac. To perform a biomechanic analysis of the ΓR and the weighted mean moment arm (WMMA) in order to calculate the resultant muscle force (FM R) of the hip extensors and flexors. To present a mechanical criteria for progression of HE exercise on the Pilates Cadillac. METHODS: Fourteen participants performed HE exercises on the Cadillac in four randomly assigned situations - using two springs (blue and red), which were attached in two positions (high and low). Angular positions were measured using an electrogoniometer. In order to calculate ΓR, the muscle torque (ΓM) and FM R, free-body diagrams and movement equations were used. The WMMA of the hip extensors and flexors were estimated from the literature. RESULTS: The ΓR and FM R presented a similar behavior during all situations; however, the maximum ΓR values did not occur at the same joint position as the FM R maximum values. The WMMA of the hip flexors presented an increased- decreased behavior with greatest values around 55º of flexion, while the hip extensors presented a similar behavior with greatest values around 25º of flexion. CONCLUSION: Biomechanic analysis of HE exercises and the evaluation of mechanical features in relation to the hip joint may be used as an objective criteria for the prescription and progression of HE exercise in Pilates.

Electromyographic activity during active prone hip extension did not discriminate individuals with and without low back pain / Atividade eletromiográfica durante o movimento de extensão do quadril em prono não discrimina indivíduos com dor lombar

BACKGROUND: Changes in activation of the trunk and hip extensor muscles can result in excessive stress on the lumbar spinal structures, predisposing them to lesions and pain. OBJECTIVES: To compare electromyographic activity of the gluteus maximus, semitendinosus and the erector spinae muscles between asymptomatic and individuals with low back pain during active prone hip extension exercises. METHODS: Fifty individuals were recruited and divided into two groups: 30 asymptomatic (24.5±3.47 years) and 20 with mechanical low back pain (28.75±5.52 years). They performed active prone hip extension exercises, while the activation parameters (latency, duration and quantity of activation) of the investigated muscles were recorded by electromyography. The beginnings of the movements were detected by a motion capture system. Differences between the groups were investigated employing Student t-tests or Mann-Whitney-U tests, according to the data distribution. RESULTS: No significant differences were found between the groups for any of the investigated muscles. Muscular activation patterns were similar for both groups, starting with the semitendinosus, followed by the erector spinae, and then, by the gluteus maximus. For both groups, significant delays in the onset of the gluteus maximus were observed. CONCLUSIONS: The assessment of the electromyographic activity was not capable of discriminating individuals with and without low back pain, suggesting an overlap in the studied populations.

CONTEXTUALIZAÇÃO: Alterações no padrão de recrutamento dos extensores de tronco e quadril podem resultar em estresse excessivo sobre estruturas da coluna lombar, predispondo-a à lesão e dor. OBJETIVOS: Comparar a atividade eletromiográfica dos músculos glúteo máximo, semitendíneo e eretores espinhais entre indivíduos assintomáticos e com dor lombar durante o exercício de extensão de quadril em prono. MÉTODOS: Cinquenta indivíduos foram recrutados e divididos em dois grupos: 30 assintomáticos (24,5±3,47 anos) e 20 com dor lombar (28,75±5,52 anos). Os parâmetros de ativação (latência, duração e quantidade de ativação) dos músculos investigados durante os exercícios de extensão de quadril foram registrados por meio da eletromiografia. O início e o término do movimento foram detectados por um sistema de análise de movimento. Diferenças entre os grupos foram investigadas utilizando-se teste t de Student ou Mann-Whitney-U, dependendo da distribuição. RESULTADOS: Não foram observadas diferenças significativas entre os grupos para nenhum dos músculos investigados. O padrão de recrutamento foi similar para os dois grupos, iniciando-se pelo semitendíneo, seguido pelos paravertebrais e finalizado pelo glúteo máximo. Nos dois grupos, observou-se um aumento significativo na latência do glúteo máximo comparado aos demais músculos. CONCLUSÕES: A avaliação do padrão de recrutamento não foi capaz de separar indivíduos com e sem dor lombar, sugerindo ocorrer uma sobreposição entre as populações estudadas.

DIFFERENCE BETWEEN UPPER AND LOWER LUMBAR SPINE LORDOSIS ON THE BASIS OF THE HIP EXTENSION RANGE / 体力科学

Decrease in the hip extension range of motion (HE-ROM) can cause lumbar hyperlordosis. Hyperlordosis is one of the mechanisms underlying low back pain. A diagnosis of low back pain from hyperlordosis can be used to detect the area in which hyperlordosis occurs more easily—the upper or lower lumbar spine. Twenty-one men were recruited for this study. HE-ROM was measured manually. Lumbar alignment was measured on a bed in a prone position. We extended the subject's hip by bending the bed at 4 angles (0°, 10°, 15°, 30°) and measured the spinal alignment by using a SpinalMouse. The results showed that lumbar lordosis increased at the bed angles of 15°and 30°. Only when the bed angle was changed from 0° to 30°, the increased angle of the lumbar spine was negatively correlated to the HE-ROM (r=-0.46, p<0.05), particularly that of the lower lumbar spine (r=-0.47, p<0.05). These findings suggested that lower lumbar lordosis tends to increase in individuals with poor HE-ROM. Additionally, increase in lower lumbar lordosis is attributed to the tendency to have low back pain in the lower lumbar spine.

Análise da resistência externa e da atividade eletromiográfica do movimento de extensão de quadril realizado segundo o método Pilates / Analysis of the external resistance and electromyographic activity of hip extension performed according to the Pilates method

OBJETIVOS: Comparar a ativação elétrica do reto femoral (RF), do bíceps femoral cabeça longa (BF) e semitendíneo (ST) e o torque de resistência (T R) do movimento de extensão de quadril (EQ) realizado com a mola fixada em duas posições distintas no Cadillac. MÉTODOS: 12 sujeitos realizaram 5 repetições de EQ com a mola fixada em duas posições (alta e baixa). Dados de eletromiografia (EMG) e eletrogoniometria foram coletados simultaneamente. O root mean square foi calculado e normalizado com base na contração voluntária máxima. Para o cálculo do T R, foram usados diagramas de corpo livre (DCL) e equações de movimento. ANOVA one-way foi usada para verificar as diferenças para EMG entre as posições de mola (p<0,05). RESULTADOS: Com a mola fixa na posição alta, o T R foi classificado como decrescente e ocorreu no "sentido" de flexão na maior parte da amplitude de movimento (ADM). Para posição baixa, o T R foi descrescente até 60º de flexão de quadril no sentido de flexão e, a partir daí, assumiu um comportamento crescente no sentido da extensão. CONCLUSÕES: A análise EMG pareceu acompanhar o T R, apresentando valores maiores para o RF na posição baixa e maiores valores de ativação para o BF e ST na posição alta, onde a demanda externa foi maior. Dados de EMG e T R fornecem informações complementares para prescrição de exercícios no Pilates.

OBJECTIVES: To compare the electrical activation of the rectus femoris (RF), long head of the biceps femoris (BF) and semitendinosus (ST) and the resistance torque (T R) of the hip extension (HE) movement performed on the Pilates Cadillac with the attachable spring in two different positions. METHODS: Twelve subjects performed five hip extensions with the attachable spring in two positions (high and low). Electromyography (EMG) and electrogoniometry data were colleted simultaneously. The root mean square (RMS) was calculated and normalized based on the maximal voluntary contraction. A free-body diagram (FBD) and movement equations were used to calculate T R. One-way ANOVA was used to investigate EMG differences between spring positions (p<0.05). RESULTS: When the spring was in the high position, T R was classified as descending and occurred in the "direction" of flexion over most of the range of motion (ROM). In the low position, T R descended until 60º of hip flexion, in the direction of flexion, and from there it took on an ascending pattern in the direction of extension. CONCLUSIONS: The EMG analysis seemed to follow the T R, with higher values for the RF in the low position and higher activation values for the BF and ST in the high position, where the external demand was greater. EMG and T R data supply complementary information for prescribing Pilates exercises.

Effects of Hip Flection and Extension in Supine Position on Lumbar Traction for Prolapse of Lumbar Intervertebral Disc / 中国康复理论与实践

@#Objective To compare the curative effects of lumbar traction in supine position with hip flection and extension for prolapse of lumbar intervertebral disc (PLID).Methods 84 PLID patients were all treated by lumbar traction in supine position. But, group A (42 cases) with hip flection and group B (42 cases) with hip extension. Before and after three weeks therapy, all patients were assessed by Fairbank JC index and Visual Analogue Scales (VAS) to observe the symptom and pain condition.Results The scores of Fairbank JC index and VAS scale of the patients in group A were significantly lower than those in the group B (P<0.001).Conclusion Lumbar traction in supine position with hip flection for the PLID can obviously promote the curative effects.

EFFECTS OF DIFFERENT SITTING POSTURES ON MAXIMUM LOWER EXTREMITY MUSCLE ACTIVATION AND MAXIMUM POWER IN EXPLOSIVE PEDALING EXERCISE / 体力科学

The purpose of this study was to investigate the effects of different sitting postures, by change of seat height, on lower extremity muscle activation and maximum power during explosive bicycle pedaling exercises. The subjects performed 5 sec maximum pedaling exercises at three different seat heights.‘High’ seat height was defined as 95% of leg length, ‘Middle’ was 90% and‘Low’ was 85%.<BR>The results were summarized as follows: A) At 3 revolutions, maximum power at‘High’ was significantly higher than that at‘low’. B) Pelvic angle at‘High’ was significantly higher than that at‘Low’. C) The maximum extension angle of the knee joint was a significantly high value in descend. ing order of‘High’, ‘Middle’ and‘Low’. D) mEMG of the Erector spinae and Biceps femoris at‘High’ was significantly higher than that at‘Low’. E) At‘High’, there was a significant correlation between maximum power of 3 revolutions and mEMG in the Gluteus maximus. In addition, maximum power at 3 revolutions tended to correlate with mEMG in the Biceps femoris and Vastus lateralis.<BR>These results suggest that in explosive pedaling exercises, different sitting postures by change of seat height, have different influences on hip extension muscle activation and maximum power.