This study was undertaken to examine the acute effect of interferential current on mechanical pain threshold and isometric peak torque after delayed onset muscle soreness induction in human hamstrings. Forty-one physically active healthy male volunteers aged 18-33 years were randomly assigned to one of two experimental groups: interferential current group (n = 21) or placebo group (n = 20). Both groups performed a bout of 100 isokinetic eccentric maximal voluntary contractions (10 sets of 10 repetitions) at an angular velocity of 1.05 rad · s(-1) (60° · s(-1)) to induce muscle soreness. On the next day, volunteers received either an interferential current or a placebo application. Treatment was applied for 30 minutes (4 kHz frequency; 125 μs pulse duration; 80-150 Hz bursts). Mechanical pain threshold and isometric peak torque were measured at four different time intervals: prior to induction of muscle soreness, immediately following muscle soreness induction, on the next day after muscle soreness induction, and immediately after the interferential current and placebo application. Both groups showed a reduction in isometric torque (P < 0.001) and pain threshold (P < 0.001) after the eccentric exercise. After treatment, only the interferential current group showed a significant increase in pain threshold (P = 0.002) with no changes in isometric torque. The results indicate that interferential current was effective in increasing hamstrings mechanical pain threshold after eccentric exercise, with no effect on isometric peak torque after treatment.

O treinamento excêntrico (Texc) produz adaptações musculares que minimizam a ocorrência de lesões e é usado em reabilitação e treinamento de força, mas pouco se sabe sobre seus efeitos no equilíbrio entre músculos antagonistas do joelho. As razões de torque permitem determinar esses desequilíbrios musculares. O objetivo do estudo foi avaliar os efeitos de 12 semanas de Texc nas razões de torque excêntrico (Iexc:Qexc) entre os músculos isquiotibiais (I) e quadríceps (Q). Vinte e quatro sujeitos saudáveis do sexo masculino foram distribuídos nos grupos controle (GC, n=13, idade 27,7±4,6 anos) e experimental (GE, n=11, idade 28,5±9,5 anos), submetido ao treinamento. Um dinamômetro isocinético foi utilizado para o Texc (velocidade de -60 º/s) e para as avaliações (uma a cada quatro semanas). As razões de torque medidas foram comparadas estatisticamente entre os grupos e intragrupos entre as avaliações, com nível de significância de 5%. No GE, foi observada redução das razões de torque da avaliação (AV) inicial para as demais: AV1x AV2, p=0,005; AV1x AV3, p=0,001; e AV1x AV4, p<0,001. Na avaliação final, as razões do GE foram menores quando comparadas às do GC (p=0,041). O Texc altera pois o equilíbrio dos músculos flexores e extensores do joelho: doze semanas de Texc levam à redução da razão Iexc:Qexc e ao aumento do torque extensor, sem alteração significativa do torque flexor, podendo ser usado na reabilitação para fortalecimento dos músculos extensores do joelho.

Background: Previous studies have used orientation and translation of whole-vertebrae to describe three-dimensional cervical segmental kinematics. Describing kinematics using facet joint movement may be more relevant to pathology and effects of interventions but has not been investigated in the cervical spine. This study compared the reliability of two different methods (whole-vertebrae vs facet joint) to evaluate cervical kinematics. Methods: Two healthy adults each had six cervical (C1 to T1) magnetic resonance imaging scans, two each in neutral and left and right rotation. A semi-automated method of segmentation and alignment determined the relative orientation and translation of each whole-vertebrae and translation of each facet joint. Intra-rater and inter-rater reliability was determined using limits of agreement (LOA) with 95% confidence intervals and intraclass correlation coefficients (ICC3,1 for intra-and ICC2,1 for inter-rater). Results: The LOA for intra-rater evaluation of facet movement was superior to whole vertebra translation. Both methods showed excellent intra-rater ICC3,1 (0.80 to 0.99) and inter-rater ICC2,1 (0.79 to 0.85) for all variables except for Euler angle for flexion/extension which was good (0.65). Intra-and inter-rater ICCs were better for facet movement than all measures of whole of vertebrae movement except Euler angles of axial rotation where no difference was detected. Conclusions: Measurement of three-dimensional segmental kinematics using either the facet joint or the whole-vertebrae method demonstrated excellent and comparable reliability. These findings support the use of the facet joint method as an option for describing and investigating cervical segmental kinematics.

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