Isokinetic Eccentric Exercise Research Articles

Association between Serum Biomarkers of Muscle Damage after Isokinetic Eccentric Exercise in Trained Males and Females

Eccentric exercise is well-known to induce muscle damage, and biomarkers may be related to the magnitude of impact on muscle force and muscle soreness after exercise. However, this phenomenon still needs to be investigated in more detail. The present study aimed to analyze if a correlation between muscle force, soreness, and biomarkers after eccentric exercise exists in healthy, trained 11 males and females. Eleven volunteers with previous resistance training experience performed 6 x 10 maximal isokinetic eccentric contractions of the elbow flexors in the muscle performance laboratory up to 72 hours after exercise. Peak torque was measured by maximal voluntary isometric contractions (MVIC) and muscle soreness by visual analogic scale (VAS) before, 24h, 48h, and 72h after the isokinetic eccentric exercise protocol. A fluorescence immunoassay analyzer determined Myoglobin and C-reactive protein levels. The MVIC significantly decreased while muscle soreness increased 24h, 48h, and 72h post eccentric exercise. Myoglobin significantly increased 48h and 72h after exercise. Muscle soreness was inversely correlated with MVIC 24h, 48h, and 72h and positively correlated with myoglobin 48h and 72h after eccentric exercise. The myoglobin was not correlated with muscle force. No significant correlation between C-reactive protein and muscle soreness and MVIC was found. In conclusion, our data suggest that myoglobin could be a valuable biomarker to be assessed alongside exercise-induced muscle soreness.

Effect of eccentric isokinetic exercise on muscle strength and functional recovery after anterior cruciate ligament reconstruction

BackgroundPrevious studies have shown isokinetic exercise forms an important part in reconditioning the patients after anterior cruciate ligament reconstruction (ACLR) in regaining muscle strength and knee function. Although eccentric isokinetic training has been shown to enhance quadriceps muscle strength, the application toward benefiting patients after ACLR remains controversial. The present study aims to investigate the benefits of eccentric over concentric isokinetic exercises on knee muscle strength and its value in later stage of rehabilitation, including the return-to-sport. MethodsThirty-six patients who had undergone ACLR for 4-to-6 months were assigned to receive either eccentric or concentric isokinetic training weekly for six weeks on top of their standardized post-operative exercise programme. The assessments include isokinetic test on the peak torques of quadriceps and hamstrings, single-leg hop test and ability to return-to-sport. ResultsBoth groups demonstrated significant gains on peak torques in quadriceps and hamstrings after training. At post-intervention, the peak torques for both quadriceps (p = 0.005) and hamstrings (p = 0.017) of the ACL-reconstructed limb from eccentric training were significantly higher than concentric training. The significant improvement was similarly demonstrated in the limb symmetry index (LSI) in hamstrings (p = 0.016) of the ACL-reconstructed limb from eccentric training. Moreover, eccentric group performed significantly better in single-leg hop tests (p = 0.042). Most importantly, eccentric group have higher percentages of return-to-sport (55.6 %) than concentric group (27.8 %). ConclusionA 6-week course of eccentric isokinetic training was more effective than concentric isokinetic training in increasing quadriceps and hamstrings strength in terms of peak torques. Importantly, the better functional performance after the eccentric isokinetic exercise account for higher return-to-sport ratio.

Skeletal muscle and cerebral oxygenation levels during and after submaximal concentric and eccentric isokinetic exercise

ABSTRACT The aim was to investigate the potential differences in muscle (vastus lateralis) and cerebral (prefrontal cortex) oxygenation levels as well as in the number of repetitions and total work output between isokinetic eccentric and concentric exercise at a moderate relative intensity until exhaustion. Ten recreationally active young men underwent two isokinetic exercise sessions either concentric or eccentric, one on each randomly selected leg. The protocols were performed at 60°/s and an intensity corresponding to 60% of the maximal voluntary contraction (MVC) of each contraction type. Concentric torque was significantly lower compared to eccentric torque in both peak values and at values corresponding to 60% of MVC [230 ± 18 Nm vs. 276 ± 19 Nm (P = .014) and 137 ± 12 Nm vs. 168 ± 11 Nm, respectively (P = .010)]. The participants performed 40% more contractions during eccentric compared to concentric exercise [122 ± 15 vs. 78 ± 7, respectively]. No differences were found in the levels of oxyhaemoglobin, deoxyhemoglobin, total haemoglobin and tissue saturation index when eccentric and eccentric exercise regimes were compared (all P > .05). Our results demonstrate that eccentric exercise of moderate intensity leads to greater resistance to fatigue and more work output compared to concentric exercise, despite the comparable muscle and cerebral oxygenation levels.

The Effects of High-Intensity Interval Exercise on Skeletal Muscle and Cerebral Oxygenation during Cycling and Isokinetic Concentric and Eccentric Exercise.

The aim of the present study was to study the effects of cycling and pure concentric and pure eccentric high-intensity interval exercise (HIIE) on skeletal muscle (i.e., vastus lateralis) and cerebral oxygenation. Twelve healthy males (n = 12, age 26 ± 1 yr, body mass 78 ± 2 kg, height 176 ± 2 cm, body fat 17 ± 1% of body mass) performed, in a random order, cycling exercise and isokinetic concentric and eccentric exercise. The isokinetic exercises were performed on each randomly selected leg. The muscle and the cerebral oxygenation were assessed by measuring oxyhemoglobin, deoxyhemoglobin, total hemoglobin, and tissue saturation index. During the cycling exercise, participants performed seven sets of seven seconds maximal intensity using a load equal to 7.5% of their body mass while, during isokinetic concentric and eccentric exercise, they were performed seven sets of five maximal muscle contractions. In all conditions, a 15 s rest was adopted between sets. The cycling HIIE caused greater fatigue (i.e., greater decline in fatigue index) compared to pure concentric and pure eccentric isokinetic exercise. Muscle oxygenation was significantly reduced during HIIE in the three exercise modes, with no difference between them. Cerebral oxygenation was affected only marginally during cycling exercise, while no difference was observed between conditions. It is concluded that a greater volume of either concentric or eccentric isokinetic maximal intensity exercise is needed to cause exhaustion which, in turn, may cause greater alterations in skeletal muscle and cerebral oxygenation.

Comment: Kay et al.’s (2020) Isokinetic eccentric exercise substantially improves mobility, muscle strength, and size, but not postural sway metrics in older adults with limited regression observed following a detraining period. Eur J Appl Physiol

Comment: Kay et al.’s (2020) Isokinetic eccentric exercise substantially improves mobility, muscle strength, and size, but not postural sway metrics in older adults with limited regression observed following a detraining period. Eur J Appl Physiol

Cardiac Autonomic Responses and Adaptation to Repeated Bouts of Eccentric Exercise

PURPOSE:The current study was performed to examine the effects of acute eccentric resistance exercise (ERE) on heart rate variability (HRV) and to determine whether cardiac autonomic regulation adapts to the repeated bout effect.METHODS: Isokinetic eccentric exercise consisted of five sets of six maximal contractions of the knee extensor with an angular velocity of 90°/second. College-aged men (n=11) underwent two sessions of ERE with a 3-week interval. Muscle damage indicators such as the range of motion (ROM) and muscle echo intensity (EI) were measured. The post-exercise cardiac autonomic response was assessed by spectral analysis of HRV. Low frequency (LF) and high frequency (HF) bands, the normalized unit (nu) for each band power, and the LF-to-HF (LF/HF) ratio were determined. All variables were recorded at 24, 48, 72, and 96 hours post-exercise as well as before and immediately after ERE.RESULTS:The EI and ROM of the rectus femoris changed significantly after the maximal ERE. There was a significant interaction effect between the time and bout for EI. Significant changes in LF and HF nu were observed at 72 (1st ERE) and 96 hours (2nd ERE) after each ERE. The LF/HF ratio was also significantly increased at 24 (1st ERE) and 72 hours (2nd ERE) after each ERE. However, no interaction effects on changes in the HRV indices were observed.CONCLUSIONS: The present study suggests that acute ERE leads to cardiac autonomic imbalance for a sustained period and that repeated bouts of ERE cannot alleviate cardiac autonomic responses to exercise.

Isokinetic eccentric exercise substantially improves mobility, muscle strength and size, but not postural sway metrics in older adults, with limited regression observed following a detraining period

IntroductionEccentric exercise can reverse age-related decreases in muscle strength and mass; however, no data exist describing its effects on postural sway. As the ankle may be more important for postural sway than hip and knee joints, and with older adults prone to periods of inactivity, the effects of two 6-week seated isokinetic eccentric exercise programmes, and an 8-week detraining period, were examined in 27 older adults (67.1 ± 6.0 years).MethodsNeuromuscular parameters were measured before and after training and detraining periods with subjects assigned to ECC (twice-weekly eccentric-only hip and knee extensor contractions) or ECCPF (identical training with additional eccentric-only plantarflexor contractions) training programmes.ResultsSignificant (P < 0.05) increases in mobility (decreased timed-up-and-go time [− 7.7 to − 12.0%]), eccentric strength (39.4–58.8%) and vastus lateralis thickness (9.8–9.9%) occurred after both training programmes, with low-to-moderate weekly rate of perceived exertion (3.3–4.5/10) reported. No significant change in any postural sway metric occurred after either training programme. After 8 weeks of detraining, mobility (− 8.2 to − 11.3%), eccentric strength (30.5–50.4%) and vastus lateralis thickness (6.1–7.1%) remained significantly greater than baseline in both groups.ConclusionDespite improvements in functional mobility, muscle strength and size, lower-limb eccentric training targeting hip, knee and ankle extensor muscle groups was not sufficient to influence static balance. Nonetheless, as the beneficial functional and structural adaptations were largely maintained through an 8-week detraining period, these findings have important implications for clinical exercise prescription as the exercise modality, low perceived training intensity, and adaptive profile are well suited to the needs of older adults.

Altered Position Sense after Submaximal Eccentric Exercise-inducing Central Fatigue.

The purpose of this study was to concomitantly investigate the acute and delayed effects of a submaximal eccentric-induced muscle fatigue on the position sense and the neuromuscular function of the right knee extensor muscles. Thirteen young and physically active participants performed a unilateral isokinetic eccentric exercise of their right lower limb until a decrease in maximal voluntary isometric contraction (MVIC) of 20% was reached. Neuromuscular (i.e., MVIC, voluntary activation (VA) level, and evoked contractile properties [DB100 and DB10]) and psychophysical evaluations (i.e., bilateral position-matching task, perceived muscle soreness, and perceived fatigue) were performed at four time points: before (PRE), immediately after (POST), 24 (POST24), and 48 (POST48) the exercise. The acute 20% MVIC reduction (P < 0.001) was associated with both central (i.e., -13% VA decrease, P < 0.01) and peripheral (i.e., -18% and -42% reduction of DB100 and DB10, respectively, P < 0.001) fatigue. In the following days (POST24 and POST48), VA levels had recovered despite the presence of a persisting peripheral fatigue and delayed-onset muscle soreness. Knee position sense, as revealed by position errors, was significantly altered only at POST (P < 0.05) with participants overestimating the length of their knee extensor. Position errors and VA deficits were significantly correlated at POST (r = -0.60, P = 0.03). Position errors returned to nonsignificant control values in the following days. The acute central fatigue induced by the eccentric exercise contributes to the position sense disturbances. Central fatigue might lead to alterations in the sensory structures responsible for the integration and the processing of position-related sensory inputs.

Effect of acupuncture plus exercise on pain and motor function in patients with knee osteoarthritis

Objective: To observe the effects of acupuncture combined with isokinetic eccentric exercise on pain and motor function in patients with knee osteoarthritis (KOA).

Comparison of The Effects of Concentric And Eccentric Isokinetic Exercises in Patients With Knee Osteoarthritis

Comparison of The Effects of Concentric And Eccentric Isokinetic Exercises in Patients With Knee Osteoarthritis

Increased erythrocyte aggregation following an acute bout of eccentric isokinetic exercise does not exceed two days.

Isokinetic exercise is used to reduce strength imbalance and to enhance performance. The aim of this study was to investigate the acute effects of a single bout of eccentric isokinetic exercise on hemorheology (erythrocyte deformability and aggregation), total oxidant/antioxidant status (TOS/TAS) and oxidative stress index (OSI) in active individuals. The study comprises 11 active, healthy, male subjects (mean age of 19.45 ± 0.31 years, BMI 22.05 ± 0.51 kg/m2). They performed single, unilateral eccentric contractions of knee flexors and extensors with dominant leg on a dynamometer. Isokinetic hamstring, quadriceps strength were recorded at eccentric (30, 120° s-1) angular velocities. Eight active age-matched healthy male subjects were included as a control group, who did not receive exercise. Blood samples were obtained before, immediately after and two days after the exercise session. Hemorheological parameters were measured by an ektacytometer. TOS/TAS were determined using a commercial kit. A session of eccentric isokinetic exercise did not affect erythrocyte deformability and oxidative stress indices, whereas red blood cell (RBC) aggregation was increased initially and returned to pre-exercise levels after two days following exercise. Our results suggest that, increased RBC aggregation following an acute bout of isokinetic exercise may result in increased plasma skimming that augments tissue perfusion and clearance of metabolites within a period of two days following exercise.

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

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

The cardiovascular impact of intense eccentric isokinetic exercise versus aerobic treadmill running

BACKGROUND: Regular physical activity is an important health factor, but intense physical stress can increase the risk of heart disease. OBJECTIVE:Our aim was to determine the potential cardiac repercussions of, and the oxidative stress resulting from a maximal eccentric isokinetic exercise and a 1-hour treadmill run at 75% ˙

The Effects of Imagery on Muscle Performance and Pain Perception Associated with Delayed-Onset Muscle Soreness

Research has indicated that imagery may aid in recovery from injuries and reduce the perception of pain in athletes during and after competitions. There is little research concerning acute pain and soreness, such as delayed-onset muscle soreness (DOMS). The purpose of this investigation was to determine whether the use of guided imagery for healing will affect soreness, pressure pain threshold (PPT), and muscle performance associated with DOMS. It was hypothesized that those who listened to a healing imagery script following inducement of DOMS would report less soreness, higher pain threshold, and have better muscle performance than a control group. Participants (thirty-eight) completed two days of testing with 48 hours between them. At the end of the first day, DOMS was induced by performing 6 sets of 15 reps of isokinetic eccentric exercise at -1.05 rad/sec. 20 participants listened to a healing imagery script 10 times within the 48 hours after inducement of DOMS while 18 listened to relaxing music. Each day consisted of tests of soreness, PPT, vertical jump, and a Wingate test. Healing imagery had no significant impact on perception of soreness, PPT, or vertical jump. The healing imagery group performed significantly better than the control group on the Wingate test in minimum power and power drop results following DOMS. Thus, it appears that imagery could impact long duration anaerobic performance as opposed to short duration explosive performance. Further research is needed to determine if healing imagery can improve performance on longer anaerobic and possibly aerobic activities. Additionally, it is possible that the limited exposure to the imagery in this investigation limited its ability to impact muscle performance and pain perception.

Adaptation of local muscle blood flow and surface electromyography to repeated bouts of eccentric exercise.

The aim of this randomized controlled crossover study was to investigate the effect of a bout of unaccustomed eccentric exercise (ECC) followed by a consecutive bout of the same intensity on local muscle blood flow, amplitude, and frequency of the electromyographic (EMG) signal from the exercised tibialis anterior muscle. Sixteen healthy male participants (age, 25.7 (0.6) years; body mass index 24.8 (1) kg·m(-2) participated in this study. Two identical bouts of high-intensity ECC were performed on the tibialis anterior muscle 7 days apart. Control sessions involving no exercise were performed 4 weeks either before or after the exercise sessions. Changes in local total blood flow [ΔtHb], EMG root mean square, and median power frequency were recorded during isometric maximum voluntary contraction of ankle dorsiflexion. Measurements were performed before, immediately after, and the day after both ECCs (ECC1 and ECC2). The participants rested quietly in a chair in the control session. Eccentric exercise 1 led to a significant decrease in [ΔtHb] on the day after (p ≤ 0.05), whereas ECC2 did not. Median power frequency decreased significantly in ECC2 compared with ECC1 (p < 0.01). Root mean square was unchanged in all the instants. The present study showed that adaptation is depicted in the local muscle blood flow and the frequency contents of the EMG after an unaccustomed ECC inducing muscle soreness. These alterations provide a potential mechanism for a rapid adaptation, which decreases susceptibility of the muscle to develop further soreness in the subsequent ECC bout.

Acute effects of dynamic exercises on the relationship between the motor unit firing rate and the recruitment threshold

The aim of this study was to compare the acute effects of concentric versus eccentric exercise on motor control strategies. Fifteen men performed six sets of 10 repetitions of maximal concentric exercises or eccentric isokinetic exercises with their dominant elbow flexors on separate experimental visits. Before and after the exercise, maximal strength testing and submaximal trapezoid isometric contractions (40% of the maximal force) were performed. Both exercise conditions caused significant strength loss in the elbow flexors, but the loss was greater following the eccentric exercise (t=2.401, P=.031). The surface electromyographic signals obtained from the submaximal trapezoid isometric contractions were decomposed into individual motor unit action potential trains. For each submaximal trapezoid isometric contraction, the relationship between the average motor unit firing rate and the recruitment threshold was examined using linear regression analysis. In contrast to the concentric exercise, which did not cause significant changes in the mean linear slope coefficient and y-intercept of the linear regression line, the eccentric exercise resulted in a lower mean linear slope and an increased mean y-intercept, thereby indicating that increasing the firing rates of low-threshold motor units may be more important than recruiting high-threshold motor units to compensate for eccentric exercise-induced strength loss.

Isoload vs isokinetic eccentric exercise: a direct comparison of exercise-induced muscle damage and repeated bout effect

This study compared the exercise induced muscle damage and repeated bout effect after isoload vs isokinetic eccentric supra-maximal single session. Thirty sport science male students were randomly divided in isokinetic (IK) and isoload (IL) eccentric training. Creatin kinase (CK) serum activity, muscle soreness and strength decrement measured both in dynamic and isometric modalities were recorded at baseline, immediately after and up to 4 days following 48 supramaximal IK or IL eccentric contractions. Same protocol was repeated after 4 weeks. A three-way repeated measures ANOVA was used to detect differences in dependent variables comparing group × bout × time. No three-way interaction occurred in dependent variables. Bout × time resulted in a significant interaction in all dependent variables. Muscle damage markers resulted significantly altered compared to baseline up to 4 days. However, IL showed significantly greater CK, muscle soreness and strength deficit compared to IK. All parameters were significantly reduced after second compared to first bout. Difference between IL and IK after second bout was not overall significant. IK vs IL supra-maximal eccentric contraction is showed to have different muscle damage symptoms. Protection conferred by first bout reduced muscle damage after 4 weeks and decreased difference between IL and IK.

Is isokinetic eccentric exercise dangerous for the heart?

Is isokinetic eccentric exercise dangerous for the heart?

Velocity-Specific Strength Recovery After a Second Bout of Eccentric Exercise

A bout of eccentric exercise (ECC) has the protective effect of reducing muscle damage during a subsequent bout of ECC known as the "repeated bout effect" (RBE). The purpose of this study was to determine if the RBE is greater when both bouts of ECC are performed using the same vs. different velocity of contraction. Thirty-one right-handed participants were randomly assigned to perform an initial bout of either fast (3.14 rad·s [180°·s]) or slow (0.52 rad·s [30°·s]) maximal isokinetic ECCs of the elbow flexors. Three weeks later, the participants completed another bout of ECC at the same velocity (n = 16), or at a different velocity (n = 15). Indirect muscle damage markers were measured before, immediately after, and at 24, 48, and 72 hours postexercise. Measures included maximal voluntary isometric contraction (MVC) strength (dynamometer), muscle thickness (MT; ultrasound), delayed onset muscle soreness (DOMS; visual analog scale), biceps and triceps muscle activation amplitude (electromyography), voluntary activation (interpolated twitch), and twitch torque. After the repeated bout, MVC strength recovered faster compared with the same time points after the initial bout for only the same velocity group (p = 0.017), with no differences for all the other variables. Irrespective of velocity, MT and DOMS were reduced after the repeated bout compared with that of the initial bout at 24, 48, and 72 hours with a corresponding increase in TT at 72 hours (p < 0.05). Faster recovery of isometric strength associated with a repeated bout of ECC was evident when the velocity was matched between bouts, suggesting that specificity effects contribute to the RBE. The current findings support the idea of multiple mechanisms contributing to the RBE.

Reductive stress after exercise: The issue of redox individuality

Exercise has been consistently used as an oxidant stimulus in redox biology studies. However, previous studies have focused on group differences and did not examine individual differences. As a result, it remains untested whether all individuals experience oxidative stress after acute exercise. Therefore, the main aim of the present study was to investigate whether some individuals exhibit unexpected responses after an acute eccentric (i.e., muscle-damaging) exercise session. Ninety eight (N = 98) young men performed an isokinetic eccentric exercise bout with the knee extensors. Plasma, erythrocytes and urine samples were collected immediately before and 2 days post-exercise. Three commonly used redox biomarkers (F2-isoprostanes, protein carbonyls and glutathione) were assayed. As expected, the two oxidant biomarkers (F2-isoprostanes and protein carbonyls) significantly increased 2 days after exercise (46% and 61%, respectively); whereas a significant decrease in glutathione levels (by −21%) was observed after exercise. A considerable number of the participants exhibited changes in the levels of biomarkers in the opposite, unexpected direction than the group average. More specifically, 13% of the participants exhibited a decrease in F2-isoprostanes and protein carbonyls and 10% of the participants exhibited an increase in glutathione levels. Furthermore, more than 1 out of 3 individuals exhibited either unexpected or negligible (from 0% to ± 5%) responses to exercise in at least one redox biomarker. It was also observed that the initial values of redox biomarkers are important predictors of the responses to exercise. In conclusion, although exercise induces oxidative stress in the majority of individuals, it can induce reductive stress or negligible stress in a considerable number of people. The data presented herein emphasize that the mean response to a redox stimulus can be very misleading. We believe that the wide variability (including the cases of reductive stress) described is not limited to the oxidant stimulus used and the biomarkers selected.