Concentric Isokinetic Exercise Research Articles

Expression of CCr5 on immune cells after eccentric or concentric isokinetic exercise

Expression of CCr5 on immune cells after eccentric or concentric isokinetic exercise

Identification of cardiac repercussions after intense and prolonged concentric isokinetic exercise in young sedentary people.

Cardiopathies are the world's leading cause of mortality and morbidity. Although rare, cardiovascular accidents can occur during intense and infrequent sporting activity, particularly among those who are unaware of their heart condition. The development of cardiospecific biochemical markers has led to a reconsideration of the role of biology in the diagnosis of cardiovascular illnesses. The aim of this study therefore was, through the use of cardiac biomarker assays, to highlight the impact of sustained physical effort in the form of intense and prolonged concentric isokinetic exercise and to research potential cardiovascular risks. Eighteen subjects participated in a maximal concentric isokinetic exercise involving 30 knee flexion-extensions for each leg. Five blood tests were taken to study the kinetics of the cardiac biomarkers. Haemodynamic parameters were measured continuously using a Portapres, and respiratory parameters were measured using a Sensormedics Vmax 29C. The results showed significant increases in the creatine kinase, myoglobin, homocysteine and haemoglobin cardiac markers. Evolutionary trends were also observed for the following biomarkers: NT-proBNP, myeloperoxydase and C-reactive protein. All the physiological parameters measured presented statistically significant changes. Isokinetic effort leads to the release of cardiac markers in the blood, but these do not exceed the reference values in healthy subjects. Maximal concentric isokinetic exercise does not, therefore, lead to an increased risk of cardiovascular pathologies.

Effects of antagonist pre-load on knee extensor isokinetic muscle performance

The aim of this study was to evaluate and compare acute effects of a reciprocal action protocol and a super-set protocol on knee extensor performance during concentric isokinetic exercise. Fourteen men aged 29.4 ± 6.1 years were tested on three different protocols, with 1 min of rest between sets: control (3 sets of 10 isokinetic knee extension repetitions), reciprocal action protocol (3 sets of 10 repetitions of reciprocal isokinetic concentric knee flexion and knee extension repetitions), and super-set protocol (3 sets of a combination of 10 repetitions of knee flexion immediately followed by 10 repetitions of knee extension repetitions). Tests were performed at 60° · s−1 and 180° · s−1, randomized across 3 days and separated by at least 72 h. There were no significant differences between protocols for peak torque at 60° · s−1 or 180° · s−1. Total work was significantly higher during the reciprocal action protocol compared with the super-set protocol at 60° · s−1. There was a significant decline in peak torque (from 240.6 to 212.9 N · m) and total work (from 2294 to 1899 J) for the control condition at 60° · s−1. Also, total work declined significantly across sets for the super-set protocol at 60° · s−1 (from 2157 to 1707 J). Results indicate that a reciprocal action protocol provides torque maintenance during multiple sets of isokinetic training, both at slow and high velocities.

Treinamento isocinético de curto prazo promove aumento da força muscular em indivíduos jovens

O objetivo foi avaliar os efeitos de treinamento isocinetico de curta duracao no desempenho muscular em individuos jovens. Onze homens sadios participaram de um programa de treinamento isocinetico de curta duracao, composto por 3 sessoes (4 series; 10 repeticoes isocineticas concentricas a 120o.s-1; 2 minutos de intervalo entre series). A reprodutibilidade dos dados de 2 sessoes foi avaliada pelo coeficiente de correlacao intraclasses (CCI) e teste de Bland e Altman. As avaliacoes do treinamento foram aplicadas pre e pos a 2a e 3a sessoes (1 serie; 3 repeticoes concentricas de extensao do joelho a 60o.s-1, 120o.s-1 e 180o.s-1). Utilizou-se a ANOVA para medidas repetidas e post-hoc de Tukey para verificar diferencas nos testes. O CCI variou de 0,97 a 0,98 em todas as velocidades. Ocorreu um aumento no pico de torque a 60o.s-1 (P=0,03) e 120o.s-1 (P=0,01) apos 2 sessoes de treinamento. Sugere-se que duas sessoes de exercicio isocinetico foram suficientes para induzir ganhos de forca na velocidade treinada (120o.s-1) e em velocidade de contracao mais lenta (60o.s-1), em individuos jovens.

Isokinetic strength training of lower limb muscles following acquired brain injury

Primary objective: To investigate the effectiveness of isokinetic strength training of ankle and knee muscles in adults with chronic acquired brain injury (ABI).Research design: Series of single case studies.Methods: Twelve people with ABI participated in a 2.5-week baseline, 12-week intervention and a 4-week follow-up phase.Intervention: Concentric isokinetic exercise, twice a week, for plantarflexors (PFs), dorsiflexors (DFs), knee flexors (KFs) and knee extensors (KEs).Outcomes: Peak torque and power at 60 and 90° s−1, PFs and KFs tone at 60° s−1, gait speed and timed chair rises.Results: For single case analyses strength improvements were noted in 11/12 participants’ PFs, 5/12 participants’ DFs and 7/12 participants’ KEs and KFs. Gait speed improved in 8/12 participants and chair rise time improved in 7/12 participants. PFs tone increased in three participants, KFs tone increased in six participants and three participants reported knee pain. For group analyses, peak torque of PFs and KEs, fast gait speed and timed chair rises demonstrated improvement (p < 0.05).Conclusions: Isokinetic strength training may be effective to improve lower limb muscle strength; however, care needs to be taken in selecting suitable candidates as some individuals reported knee pain with this intensive programme.

Effect of Light-Emitting Diodes Therapy (LEDT) on Knee Extensor Muscle Fatigue

The purpose of this study was to evaluate the effects of light-emitting diodes therapy (LEDT) on quadriceps muscle fatigue by using torque values from the isokinetic dynamometer as an outcome measure. Light therapy is considered an innovative way to prevent muscle fatigue. Although positive results have been obtained in animal models and in clinical experiments, no results are available on the effects of this therapeutic modality on human performance studies with isokinetic dynamometry. Seventeen healthy and physically active male volunteers were included in a crossover randomized double-blinded placebo-controlled trial. They performed two sessions of an isokinetic fatigue test (30 maximal concentric knee flexion-extension contractions; range of motion, 90 degrees; angular velocity, 180 degrees per second) after LEDT or placebo treatment. Maximal knee extensor muscle isokinetic voluntary contractions were performed before (PRE-MVC) and after (POST-MVC) the fatigue test. LEDT treatment was performed with a multidiode cluster probe (34 red diodes of 660 nm, 10 mW; 35 infrared diodes of 850 nm, 30 mW) at three points of the quadriceps muscle, with a total irradiating dose of 125.1 J. No differences were observed in the PRE-MVC between LEDT (284.81 ± 4.52 Nm) and placebo (282.65 ± 52.64 Nm) treatments. However, for the POST-MVC, higher torques (p = 0.034) were observed for LEDT (237.68 ± 48.82 Nm) compared with placebo (225.68 ± 44.14 Nm) treatment. LEDT treatment produced a smaller maximal isometric torque decrease after high-intensity concentric isokinetic exercise, which is consistent with an increase in performance.

The Influence of Eccentric and Concentric Exercise on Skeletal Muscle Regulators in Young Women

PURPOSE: To evaluate changes in myostatin, follistatin and MyoD mRNA gene expression using concentric exercise (CE) and eccentric exercise (EE) as a stimulus to better understand the mechanisms of muscle hypertrophy in young women. METHODS: Single-leg maximal eccentric or concentric isokinetic exercise was performed using the Cybex NormTM dynamometer (Cybex International Inc. Ronkonkoma, New York) at 60° /s. Ten sets of ten repetitions with 20 second rest between sets were completed by each subject. Three muscle biopsies of the vastus lateralis were obtained from the exercised leg at baseline (1st biopsy), 8 hours after the first exercise bout (2nd biopsy), and 8 hours after the seventh and final exercise bout performed 2 weeks after the first exercise session (3rd biopsy). mRNA gene expression was analyzed using RT-PCR methods. 18s ribosomal RNA was used as the internal standard to determine relative expression of mRNAs for myostatin, follistatin, and MyoD. Paired t-tests were used to compare changes in mRNA gene expression within groups (Eccentric or Concentric). Independent t-tests were performed to test group differences (Eccentric versus Concentric). A probability level of P ≤ 0.05 was used to determine statistical significance with Bonferroni adjustments. RESULTS: There were no significant fold changes in the CE group for myostatin, follistatin, and MyoD mRNA gene expression between the first and second biopsies as well as the first and third biopsies (P>0.17). Similarly, there were no significant changes in the EE group for the same variables (P>0.11). In addition, there were no significant differences between the EE and CE groups (P≥0.05). CONCLUSIONS: Our data suggests that a single bout or multiple bouts (7) of maximal eccentric or concentric exercise does not significantly alter myostatin, follistatin, or MyoD mRNA gene expression in young women. Therefore, the type of exercise stimulus does not appear to differentially alter mRNA gene expression of hypertrophic myogenic regulators.

8주간의 등속성 운동프로그램이 만성발목관절 염좌 상해를 입은 운동선수의 근기능 회복에 미치는 영향

The purpose of this study was to identify the effects of isokinetic exercise programs on the muscular function recovery of athletes with ankle sprain. The subjects were 12 male college athletes with chronic ankle sprain assessed by maximum inversion stress roentgnography. 12 participants were randomly assigned into two different treatment groups; concentric isokinetic exercise(CIE, n=6) and eccentric isokinetic exercise(EIE, n=6). The CIE group performed concentric contractions of each ankle dorsiflexor and plantarflexor muscles and the EIE group performed eccentric contractions of each ankle muscle group three days for eight weeks. The instrument was used a spectrum of angular velocities ranging from 30℃/sec intervals and EMG to record activity of tibialis anterior and gastrocnemius, for involved side. The results of this study were following as: 1. Muscular function 1) Dorsiflexors CIE group showed increases(p.05) in peak torque However, both training groups did not display these marked changes in the uninvolved side after the 8-week period. 2) Plantarflexors EIE group showed marked increases(p.01) in peak torque but CIE group didn`t increase in the involved side. In addition, both training groups did not display these marked changes in uninvolved side after the 8-week period. 3) Ⅳ/UV ratio of dorsiflexior CIE group showed marked decreases(p.01) in the Ⅳ/UV ratio of dorsiflexior. However, EIE group did not display these marked changes after the 8-week period. 2.EMG EIE group showed marked increases(p.01) in the gastrocnemius. However, both training groups did not display marked changes in other sides after the 8-week period. These results also indicated that the same eccentric isokinetic exercise as concentric isokinetic exercise; however, the improvements in the Ⅳ/UV ratio of dorsilflexior were better in the CIE group compared with the EIE group after train training. The findings of these results implied that with isokinetic exercise programs used in this study, it is possible to recover muscular function in athletes with chronic ankle sprain. It was also indicated that extensive training involving a high number of repetitions and eccentric contractions was safe, effective, and well tolerated for the athletes with chronic ankle sprain.

Study of the control strategy of the quadriceps muscles in anterior knee pain.

Anterior knee pain (AKP) is a common pathological condition, particularly among young people and athletes, associated to an abnormal motion of the patella during the bending of the knee and possibly dependent on a muscular or structural imbalance. A lack of synergy in the quadriceps muscles results in a dynamic misalignment of the patella, which in turn produces pain. AKP rehabilitative therapy consists of conservative treatment whose main objective is to strengthen the Vastus Medialis. The aim of this article is to study the quadriceps muscle control strategy in AKP patients during an isokinetic exercise. Analysis of the muscle activation strategy is important for an objective measurement of the knee functionality in that it helps to diagnose and monitor the rehabilitative treatment. Surface electromyography (EMG) from the three superficial muscles of the femoral quadriceps during a concentric isokinetic exercise has been analyzed along with the signals of knee joint position and torque. A group of 12 AKP patients has been compared with a group of 30 normal subjects. Analysis of the grand ensemble average of the EMG linear envelopes in AKP patients reveals significant modifications in Vastus Medialis activity compared to the other quadriceps muscles. In order to study the synergy of the muscles, temporal identifiers have been associated to the EMG linear envelopes. To this end, EMG linear envelope decomposition in Gaussian pulses turned out to be effective and the results highlight an appreciable delay in the activation of the Vastus Medialis in AKP patients. This muscular unbalance can explain the abnormal motion of the patella.

Quadriceps muscles activation in anterior knee pain during isokinetic exercise

The aim of this paper is to study the femoral quadriceps muscles activation in patients suffering from Anterior Knee Pain (AKP) during an isokinetic exercise. AKP is a common pathological condition, associated to an abnormal motion of the patella. It possibly depends on a muscular or structural imbalance. A lack of synergy in the quadriceps muscles results in a dynamic misalignment of the patella, which in turn produces pain. A quantitative analysis of the muscle activation strategy is important for an objective measurement of the knee functionality in that it helps to diagnose and monitor the rehabilitative treatment. Surface electromyography (EMG) from the three superficial muscles of the femoral quadriceps during a concentric isokinetic exercise has been analysed. A group of AKP patients has been compared with a control group of healthy subjects. Ensemble average of the EMG linear envelopes reveals significant modifications in Vastus Medialis activity in AKP patients. In order to quantify the synergy of the muscles, different parameters have been associated to EMG linear envelopes significant features. A decomposition in gaussian pulses and an asymmetry coefficient have been utilised. The results relative to these concise parameters highlight an appreciable delay and a modification in the activation of the Vastus Medialis in AKP patients.

MECHANOMYOGRAPHIC, ELECTROMYOGRAPHIC, AND PEAK TORQUE RESPONSES TO CONCENTRIC ISOKINETIC MUSCLE ACTIONS OF THE BICEPS BRACHII 1413

The purpose of this investigation was to examine the effects of velocity of muscle action on the electromyographic (EMG) and mechanomyographic (MMG) responses to concentric isokinetic exercise of the biceps brachii. Ten adult males (age=20-27 yrs) performed maximal concentric muscle actions of the forearm flexors at velocities of 30, 90, and 150°·s-1 on a Cybex 6000 isokinetic dynamometer. Bipolar surface EMG electrodes were placed over the biceps brachii muscle of the dominate arm with a piezoelectric MMG recording device placed between the EMG electrodes. One way repeated measures ANOVA's with Tukey post-hoc procedures were used to determine differences across the velocities for peak torque, EMG, and MMG.Table The results of the present study indicated a velocity-related dissociation between the peak torque and MMG responses to concentric isokinetic muscle actions during forearm flexion. This is in agreement with previous findings for the leg extensors (vastus lateralis). The present findings in conjunction with previous findings for the vastus lateralis suggest that the velocity-related increase in MMG during concentric isokinetic muscle actions is independent of muscle architecture (pennate vs. fusiform).