Contralateral effects of eccentric resistance training on immobilized arm

This study compared the effects of contralateral eccentric‐only (ECC) and concentric‐/eccentric‐coupled resistance training (CON‐ECC) of the elbow flexors on immobilized arm. Thirty healthy participants (18‐34 y) were randomly allocated to immobilization only (CTRL; n = 10), immobilization and ECC (n = 10), or immobilization and CON‐ECC group (n = 10). The non‐dominant arms of all participants were immobilized (8 h·day^?1) for 4 weeks, during which ECC and CON‐ECC were performed by the dominant (non‐immobilized) arm 3 times a week (3‐6 sets of 10 repetitions per session) with an 80%‐120% and 60%‐90% of one concentric repetition maximum (1‐RM) load, respectively, matching the total training volume. Arm circumference, 1‐RM and maximal voluntary isometric contraction (MVIC) strength, biceps brachii surface electromyogram amplitude (sEMG_RMS), rate of force development (RFD), and joint position sense (JPS) were measured for both arms before and after immobilization. CTRL showed decreases (P < .05) in MVIC (?21.7%), sEMG_RMS (?35.2%), RFD (?26.0%), 1‐RM (?14.4%), JPS (?87.4%), and arm circumference (?5.1%) of the immobilized arm. These deficits were attenuated or eliminated by ECC and CON‐ECC, with greater effect sizes for ECC than CON‐ECC in MVIC (0.29: +12.1%, vs ?0.18: ?0.1%) and sEMG_RMS (0.31:17.5% vs ?0.15: ?5.9%). For the trained arm, ECC showed greater effect size for MVIC than CON‐ECC (0.47 vs 0.29), and increased arm circumference (+2.9%), sEMG_RMS (+77.9%), and RDF (+31.8%) greater (P < .05) than CON‐ECC (+0.6%, +15.1%, and + 15.8%, respectively). The eccentric‐only resistance training of the contralateral arm was more effective to counteract the negative immobilization effects than the concentric‐eccentric training.     

Concentric or eccentric training effect on eccentric exercise-induced muscle damage.

PURPOSE: The purpose of this study was to compare changes in muscle damage indicators following 24 maximal eccentric actions of the elbow flexors (Max-ECC) between the arms that had been previously trained either eccentrically or concentrically for 8 wk. METHODS: Fifteen subjects performed three sets of 10 repetitions of eccentric training (ECC-T) with one arm and concentric training (CON-T) with the other arm once a week for 8 wk using a dumbbell representing 50% of maximal isometric force of the elbow flexors (MIF) determined at the elbow joint of 90 degrees (1.57 rad). The dumbbell was lowered from a flexed (50 degrees, 0.87 rad) to an extended elbow position (180 degrees, 3.14 rad) in 3 s for ECC-T, and lifted from the extended to the flexed position in 3 s for CON-T. Max-ECC was performed 4 wk after CON-T and 6 wk after ECC-T. Changes in MIF, range of motion (ROM), upper arm circumference (CIR), muscle soreness (SOR), and plasma creatine kinase (CK) activity were compared between the ECC-T and CON-T arms. RESULTS: The first ECC-T session produced larger decreases in MIF and ROM, and larger increases in CIR and SOR compared with CON-T. CK increased significantly (P < 0.01) and peaked 4 d after the first training session, but did not increase in the following sessions. All measures changed significantly (P < 0.01) following Max-ECC; however, the changes were not significantly different between ECC-T and CON-T arms. CONCLUSION: These results showed that ECC-T did not mitigate the magnitude of muscle damage more than CON-T, and CON-T did not exacerbate muscle damage.     

The effects of preexercise stretching on muscular soreness, tenderness and force loss following heavy eccentric exercise

The present study sought to investigate the effects of preexercise stretching on delayed onset muscle soreness (DOMS), i.e. soreness, tenderness and loss of muscle force, that usually occurs after strenuous or unaccustomed eccentric exercise. Ten female volunteers performed 10 sets of 10 maximal isokinetic eccentric contractions for knee flexion with both legs after a 5-min ergometer cycling warm-up. Prior to the exercise for one leg, randomly chosen, 4 x 20 s of static stretching for the hamstring muscle group was implemented. Rated soreness, tenderness on algometer pressure and loss of maximal eccentric contractile force was evaluated preexercise and 24, 48 and 96 h postexercise. The exercise bout produced severe DOMS, with parameters peaking and troughing at 48 h postexercise. However, no significant differences were found, regarding any of the parameters, when comparing stretched and nonstretched legs. The present study thus suggests that preexercise static stretching has no preventive effect on the muscular soreness, tenderness and force loss that follows heavy eccentric exercise.     

Cross transfer effects of muscular endurance during training and detraining

BACKGROUND: To clarify 1) how the cross-transfer effect, obtained in a contralateral untrained forearm through a 4-week ipsilateral endurance training regimen, is changed during detraining; and 2) how blood flow to the untrained limb is related to the transfer effect of muscular endurance during training and detraining periods. METHODS: Training regimen: hand-grip training by means of a hand-ergometer with a work-load of 1/3 of the maximum handgrip strength 5 times a week for 4 weeks. Blood flow: a mercury-in-rubber strain-gauge for venous occlusion plethysmography. Measures: 1) maximal number of contractions to determine the muscular endurance; 2) reactive hyperaemic blood flow response (RHBF3) to determine whether maximal vasodilatory capacity would be changed in both the forearms post-training and detraining; and 3) maximal work-related blood flow. RESULTS: We found significant increments both in the muscle endurance and the maximal work-related blood flow not only in the trained (+125%, +30%) but also in the untrained (+40%, +19%) forearms. During detraining, we found decreases both in the muscle endurance and the maximal work-related blood flow (-22%, p<0.01; -16%, p=0.053) of the trained forearm. However, in the untrained arm (-3%, NS) the cross-transfer effect of muscular endurance remained unchanged despite a drop in the maximal work-related blood flow (-17%, p<0.05). The RHBF3 did not change in either of the forearms during the whole periods. CONCLUSIONS: These findings suggest that the maintenance of the cross transfer effect of muscle endurance during detraining cannot be explained on the basis of changes in forearm blood flow.     

Resistance training effects on muscular strength of elderly are related to intensity and gender

The purpose of this study was to determine whether a high intensity (HI) versus a moderate (MI) or low-intensity (LI) training program would be more effective in improving the isokinetic knee extension muscular performance in healthy inactive men and women. Sixty-four participants, men and women, were randomly assigned to one of four groups: control group (C), LI (50% of 1RM), the MI group (70% of 1RM) and the HI (90% of 1RM). Participants exercised on three resistance exercise machines: leg extension, leg curls and leg press. The isokinetic testing method (concentric mode) applied prior to and at the end of the training period (16 weeks, three 3 times per week) to assess the knee muscular performance. MANOVA repeated measures revealed that the HI group demonstrated the most strength gains following a speed specificity pattern (most considerable improvement occurred at or near slow speeds from 7.3% to 11.2% for male and from 2.3% to 15.2% for female). In addition, males demonstrated a greater improvement of knee extension power output than females. In conclusion, HI strength training is proposed for elderly men and women as the most effective protocol. Furthermore only at low-velocity testing, women of the HI showed a greater change than men (p < 0.05). Regarding strength increase in relation to various testing velocities, a greater increase was found in HI at low velocities, with the other training groups exhibiting almost similar strength increase at all tested speeds.     

Specific and transfer effects induced by arm or leg training

The purpose of the present study was to examine both the specific and the transfer effects of a Square Wave Endurance Exercise Test (SWEET) and to investigate the determining factors of transfer effect. A control group (CG, n = 5) and 2 experimental groups were studied. Experimental groups completed 3 days/week a 45 min SWEET over 6 weeks, either with the arms using a wheelchair ergometer (AG, n = 5) or with the legs using a cycling ergometer (LG, n = 5). All subjects performed before and after training two maximal progressive tests: the first one with the arms and the second with the legs. During those tests oxygen uptake (VO(2)) and cardiorespiratory parameters were continuously measured. Specific effects (changes between the tests performed with trained limbs) were observed: the peak power output (W(p)) and VO(2) were significantly increased by both arm (+ 66 %, + 35 %) and leg (+ 17 %, + 14 %) training. At ventilatory threshold (VT), power output (W) and VO(2) were significantly increased with arm (+ 145 % and + 51 %) and leg (+ 53 % and + 46 %) training. Transfer effects (changes between pre and post tests performed with untrained limbs) were observed: W(p) and VO(2) were not increased in AG while W(p) was increased in LG (+ 11 %). At VT, W and VO(2) were increased with arm (+ 19 % and + 23 %) and leg (+ 33 % and + 46 %) training. For AG and LG the VO(2) expressed in percent of the VO(2) peak was increased (+ 19 % and + 33 %, respectively) and the O(2p) was also increased (+ 30 %) for LG. These results show that SWEET training induced specific and transfer effects. Moreover, the initial level of the subjects, the type and the intensity of the training seem to be the major factors for effective observable transfer effects.     

Effect of reduced training frequency on muscular strength

Twenty-four men and 26 women (25 +/- 5 years) participating in 10 weeks (n = 27) and 18 weeks (n = 23) of variable resistance strength training programs were recruited to complete 12 weeks of reduced training. Training consisted of one set of 7-10 bilateral knee extensions performed to volitional failure. Prior to the reduced training phase of the project, the subjects were training either 2 days.week-1 (n = 23) or 3 days.week-1 (n = 18). The subjects who trained 3 days.week-1 reduced training frequency to 2 days.week-1 (n = 9), 1 day.week-1 (n = 7), or 0 days.week-1 (n = 2). The subjects who trained 2 days.week-1 reduced training frequency to 1 day.week-1 (n = 12) or 0 days.week-1 (n = 11). Nine subjects served as controls and did not train. Isometric knee extension strength was assessed at 9, 20, 35, 50, 65, 80, 95, and 110 degrees of knee flexion on two separate occasions prior to and immediately post-training and following reduced training. After training, mean relative increases in peak isometric knee extension strength and dynamic training weight were 21.4% +/- 17.5% (P less than or equal to 0.01) and 49.5% +/- 14.7% (P less than or equal to 0.01), respectively. The subjects who stopped training (0 days.week-1) lost 68% (P less than or equal to 0.01) of the isometric strength gained during training.(ABSTRACT TRUNCATED AT 250 WORDS)     

Effect of eccentric training on the plantar flexor muscle-tendon tissue properties

PURPOSE: It has been shown that eccentric training can be effective in the rehabilitation of patients with Achilles tendonopathy. The mechanism behind these results is not clear. However, there is evidence that tendons are able to respond to repeated forces by altering their structure and composition, and, thus, their mechanical properties change. In this regard, the objective of the present study was to investigate whether eccentric training affects the mechanical properties of the plantar flexor's muscle-tendon tissue properties. METHODS: Seventy-four healthy subjects were randomized into two groups: an eccentric training group and a control group. The eccentric training group performed a 6-wk eccentric training program for the calf muscles. Before and after this period, all subjects were evaluated for dorsiflexion range of motion using universal goniometry, passive resistive torque of the plantar flexors, and stiffness of the Achilles tendon. Passive resistive torque was measured during ankle dorsiflexion on an isokinetic dynamometer. Stiffness of the Achilles tendon was assessed using a dynamometer, in combination with ultrasonography. RESULTS: The results of the study reveal that the dorsiflexion range of motion was significantly increased only in the eccentric training group. The eccentric heel drop program also resulted in a significant decrease of the passive resistive torque of the plantar flexors (from 16.423 +/- 0.827 to 12.651 +/- 0.617 N.m). The stiffness of the Achilles tendon did not change significantly as a result of training. CONCLUSION: These findings provide evidence that an eccentric training program results in changes to some of the mechanical properties of the plantar flexor muscles. These changes were thought to be associated with modifications to structure rather than to stretch tolerance.     

Effects of prior concentric training on eccentric exercise induced muscle damage

BACKGROUND: Exercise induced muscle damage (EIMD) from strenuous unaccustomed eccentric exercise is well documented. So too is the observation that a prior bout of eccentric exercise reduces the severity of symptoms of EIMD. This has been attributed to an increase in sarcomeres in series. Recent studies have suggested that prior concentric training increases the susceptibility of muscle to EIMD following eccentric exercise. This has been attributed to a reduction of sarcomeres in series, which decreases muscle compliance and changes the length-tension relation of muscle contraction. OBJECTIVE: To assess the effects of prior concentric training on the severity of EIMD. METHODS: Four men and four women (mean (SD) age 21.1 (0.8) years) followed a four week concentric training programme. The elbow flexor musculature of the non-dominant arm was trained at 60% of one repetition maximum dynamic concentric strength performance, three times a week, increasing to 70% by week 3. After three days of rest, participants performed 50 maximal isokinetic eccentric contractions on both arms. All participants gave written informed consent before taking part in this study, which was approved by the school ethics committee. Strength, relaxed arm angle (RAA), arm circumference, and soreness on active extension and flexion were recorded immediately before eccentric exercise, one hour after, and at 24 hour intervals for three days. Data were analysed with fully repeated measures analyses of variance. RESULTS: Strength retention was significantly (p<0.01) greater in the control arm than the trained arm (84.0 (13.7)%, 90.4 (14.7)%, 95.2 (10.5)%, 103.5 (7.6)% v 75.5 (11.3)%, 77.6 (15.3)%, 80.1 (13.9)%, 80.9 (12.5)%) at one, 24, 48, and 72 hours respectively. Similarly, soreness was greater in the trained arm (0.7 (0.6), 3.1 (1.4), 3.0 (1.5), 1.9 (2.3)) than in the untrained arm (0 (0.2), 1.6 (1.3), 1.4 (0.6), 0.6 (0.4)) at one, 24, 48, and 72 hours respectively (p<0.05). Concentric training induced a significant reduction in RAA (165.2 (6.7) degrees v 157.3 (4.9) degrees ) before the eccentric exercise bout (p<0.01). This was further reduced and remained lower in the trained arm at all time points after the eccentric exercise (p<0.01). The arm circumference of the concentrically trained arm was significantly greater than baseline (p<0.05) at 72 hours (30.3 (2.9) v 29.8 (3.3) cm). CONCLUSIONS: These findings extend the understanding of the effects of prior concentric training in increasing the severity of EIMD to an upper limb exercise model. The inclusion of concentric conditioning in rehabilitation programmes tends to exacerbate the severity of EIMD in subsequent unaccustomed exercise. However, where concentric conditioning is indicated clinically, the net effect of conditioning outcome and EIMD may still confer enhanced strength performance and capability to dynamically stabilise a joint system.     

Gender and eccentric training in Achilles mid-portion tendinopathy

The role of gender in Achilles tendinopathy is yet to be determined. We hypothesized that female patients respond the same as males to 12 weeks of painful eccentric training. A total number of 75 consecutive mid-portion patients with Achilles tendinopathy (25 females, 38 males) were enrolled in a cohort study with 63 being analyzed after 12 weeks according to their gender for tendon and paratendon microcirculatory mapping. Outcome was determined by pain on visual analogue scale, VISA-A score, Foot Ankle Outcome Score (FAOS), tendon and paratendon capillary blood flow, oxygen saturation, and postcapillary venous filling pressures. Eccentric training resulted in a morning resting pain reduction by 44% in males (P = 0.001) and by 27% in females (P = 0.08). VISA-A score improved in males by 27% from 63 ± 12 to 86 ± 13 (P = 0.036) and by 20% in females from 60 ± 14 to 75 ± 11 (P = 0.043, P < 0.05 for gender difference). Among females, only one out of five FAOS items was increased (sport 72 ± 21 to 82 ± 15, P = 0.045), while in males, four out of five items were increased (symptoms, pain, all-day-life, and sport, all P < 0.01). The microcirculatory gender-specific response to eccentric training revealed a greater postcapillary venous filling pressure reduction among symptomatic females and inconclusive capillary blood flow changes. No change in tendon oxygenation was noted in both genders. Symptomatic females suffering Achilles tendinopathy do not benefit as much as symptomatic males from 12 weeks of eccentric training. The pain reduction is significantly lower among symptomatic females in contrast to males, and the improvement in the FAOS and VISA-A scores is significantly lower among females in contrast to males. Additional treatment options warrant scrutiny to symptomatic females suffering Achilles tendinopathy beyond eccentric training.     

Central versus peripheral adaptations following eccentric resistance training

Aim of the present investigation was to study the effects of an eccentric training on the neuromuscular properties of the plantar-flexor muscles. The experiment was carried out on 14 males divided into two groups (eccentric and control). Eccentric training consisted of six sets of six eccentric contractions at 120 % of one maximal concentric repetition and it was performed four times a week during four weeks. Before and after the 4-wk period, the plantar-flexor torque and the associated electromyographic activity were recorded during voluntary contractions (isometric, concentric and eccentric) and electrically induced contractions (twitch and tetanus), in order to distinguish central from peripheral adaptations. For the eccentric group, voluntary torque significantly increased after training independent of the action mode (relative gains 14 - 30 %, p < 0.05). This was associated with an increase in agonist EMG activity during isometric action and a decrease in antagonist coactivation in concentric (-27 %) and eccentric actions (-22 %) (p < 0.05). Voluntary activation level significantly increased from 80 +/- 5 % to 91 +/- 2 % (p < 0.05). Some of the twitch contractile properties (peak torque and maximal rate of twitch tension relaxation) were significantly modified (p < 0.05), but no changes were observed for the tetanus characteristics. These results allowed to conclude that the torque gains observed after the present training were more likely associated to central adaptations, affecting both agonist and antagonist muscles.     

Effects of eccentric phase velocity of plyometric training on the vertical jump

The aim of this study was to compare the effects of plyometric training performed with rapid or slow stretch contraction on jump performance and muscle properties. Thirty males between the ages of 19 and 22 volunteered for the 8-week experiment. Subjects were divided into the following three groups: training group 1 (TG1), training group 2 (TG2), and control group (CG). Each of the two experimental groups underwent a unique training regimen. For the first group (TG1, n = 12): from a standing position the subject flexed his knees to a 90 degrees angle with velocity standardized and controlled at 0.4 m/s and immediately performed a leg extension as quickly as possible. For the second group (TG2, n = 12): from a standing position, the subject flexed his knees to a 90 degrees angle with velocity standardized at 0.2 m/s and then performed a leg extension as quickly as possible. Each exercise consisted of six sets of ten repetitions with a barbell on the shoulders at 70 % of the maximal isometric force (1 RM). The 70 % load was modified at two-week intervals by evaluating a new 1 RM. Exercises were performed four times a week over the eight-week period. The third group (CG, n = 6), served as the control group. Maximal isometric force (MVC), maximal concentric force, squat jump (SJ) and counter movement jump (CMJ) exercises were performed before and after the training program. Subjects were filmed (100 Hz) and each jump was divided into three phases: eccentric phase (ECC), transition phase (TR) and concentric phase (CON). Surface EMG was used to determine the changes in the electromyographic (EMG) activity before and after the training program. There was an increase in leg extension force, velocity and electrical activity for SJ and CMJ for the two training groups (p < 0.05). However, TG1 showed a significant advantage in CMJ performance as well as a significant decrease in TR compared to the TG2 (p < 0.05). The results of this study show that when plyometric training is performed with rapid stretch contraction the CMJ jump height increases and the TR decreases.     

A comparison of concentric and eccentric muscle training.

Eight male university students served as subjects in an investigation designed to develop strength using two different muscle training routines over a six week period. The subjects trained the arm and leg on one side of their bodies using concentric contractions and the arm and leg on the opposite side of their bodies with identical exercises using eccentric contractions. Concentric movements were against a resistance 80% of one-repetition-maximum (1-Rm) for 10 repetitions and two sets; eccentric movements were against a force of 120% of concentric 1-RM for 6 repetitions and two sets. Both routines produced significant gains in strength in all subjects, but neither training procedure produced dynamic or static strength gains significantly different from the other. Subjective evaluations by the subjects indicated that the eccentric training movements were easier to perform than the concentric training movements.     

Effects of eccentric versus concentric training on thigh muscle strength and EMG

The purpose of this study was to compare pure eccentric and concentric strength training regarding possible specific effects of muscle action type on neuromuscular parameters, such as a decreased inhibition during maximal voluntary eccentric actions. Two groups of young healthy adult men performed 10 weeks of either eccentric or concentric unilateral isokinetic knee extensor training at 90 degrees.s(-1), 4 sets of 10 maximal efforts, 3 days a week. Knee extensor torque and surface EMG from the quadriceps and hamstring muscle groups were collected and quantified in a window between 30 and 70 degrees knee angle (range of motion 90-5 degrees ) during maximal voluntary eccentric and concentric knee extensor actions at 30, 90, and 270 degrees.s(-1). Changes in strength of the trained legs revealed more signs of specificity related to velocity and contraction type after eccentric than concentric training. No major training effects were present in eccentric to concentric ratios of agonist EMG or in relative antagonist (hamstring) activation. Thus, for the trained leg, the muscle action type and speed specific changes in maximal voluntary eccentric strength could not be related to any effects on neural mechanisms, such as a selective increase in muscle activation during eccentric actions. Interestingly, with both types of training there were specific cross-education effects, that is, action type and velocity specific increases in strength occurred in the contralateral, untrained, leg, accompanied by a specific increase in eccentric to concentric EMG ratio after eccentric training.     

Chronic Achilles tendon pain treated with eccentric calf-muscle training

Injuries involving the Achilles tendon and manifested as chronic tendon pain are common, especially among recreational athletes. In a pilot study on a small group of patients with chronic painful mid-portion Achilles tendinosis, eccentric calf-muscle training was shown to give good clinical results. The aim of this prospective study was to investigate if the previously achieved good clinical results could be reproduced in a larger group of patients, and also to investigate the effects of eccentric calf-muscle training in patients with chronic insertional Achilles tendon pain. Seventy-eight consecutive patients, having chronic painful Achilles tendinosis at the mid-portion (2–6 cm level) in a total of 101 tendons (55 unilateral and 23 bilateral), and thirty consecutive patients with chronic insertional Achilles tendon pain in 31 tendons (29 unilateral and one bilateral) were treated with eccentric calf-muscle training for 12 weeks. Most patients were recreational athletes. Evaluation of the amount of tendon pain during activity was recorded on a visual analogue scale (VAS), before and after treatment. In 90 of the 101 Achilles tendons (89%) with chronic painful mid-portion Achilles tendinosis, treatment was satisfactory and the patients were back on their pre-injury activity level after the 12-week training regimen. In these patients, the amount of pain during activity, registered on the VAS-scale (mean±SD), decreased significantly from 66.8±19.4 to 10.2±13.7. On the contrary, in only ten of the tendons (32%) with chronic insertional Achilles tendon pain was treatment satisfactory, with a significant decrease on the VAS-scale (mean±SD), from 68.3±7.0 to 13.3±13.2. Our conclusion is that treatment with eccentric calf-muscle training produced good clinical results in patients with chronic painful mid-portion Achilles tendinosis, but not in patients with chronic insertional Achilles tendon pain.     

Intramuscular pressure and torque during isometric, concentric and eccentric muscular activity

Intramuscular pressures, electromyography (EMG) and torque generation during isometric, concentric and eccentric maximal isokinetic muscle activity were recorded in 10 healthy volunteers. Pressure and EMG activity were continuously and simultaneously measured side by side in the tibialis anterior and soleus muscles. Ankle joint torque and position were monitored continuously by an isokinetic dynamometer during plantar flexion and dorsiflexion of the foot. The increased force generation during eccentric muscular activity, compared with other muscular activity, was not accompanied by higher intramuscular pressure. Thus, this study demonstrated that eccentric muscular activity generated higher torque values for each increment of intramuscular pressure. Intramuscular pressures during antagonistic co-activation were significantly higher in the tibialis anterior muscle (42–46% of maximal agonistic activity) compared with the soleus muscle (12–29% of maximal agonistic activity) and was largely due to active recruitment of muscle fibers. In summary, eccentric muscular activity creates higher torque values with no additional increase of the intramuscular pressure compared with concentric and isometric muscular activity.     

Effects of a 7-day eccentric training period on muscle damage and inflammation

PURPOSE: This study examined the effects of a 7-d repeated maximal isokinetic eccentric training period on the indicators of muscle damage and inflammatory response. METHODS: Twenty-two college-age males were randomly assigned to eccentric training (ET) (N = 12) and control groups (CON) (N = 10). The initial exercise was 30 repetitions of maximal voluntary isokinetic eccentric contraction (ECC1) on nondominant elbow flexors with Cybex 6000 at 60 degrees.s-1 angular velocity. The ET group performed the same exercise for the following 6 consecutive days (referred to as ECC2 to ECC7) after ECC1. Upper arm circumference (CIR), range of motion (ROM), and maximal isometric force (MIF) were measured before, immediately after, and every 24 h for 7 consecutive days after ECC1. Plasma creatine kinase (CK), lactate dehydrogenase (LDH), glutamic oxaloacetate transaminase (GOT), leukocyte counts, and serum interleukin-1beta and -6 (IL-1beta, IL-6) levels were assessed before; at 2 h; and at 1, 3, 4, 6, and 7 d after ECC1. Muscle soreness was measured before and for 7 consecutive days after ECC1. RESULTS: The ECC1 produced significant changes in most of the measures for both groups (P < 0.05), with the exception of leukocyte counts (P > 0.05). No indicators of increased damage (P > 0.05) were found from ECC2 to ECC7 for the ET group. CONCLUSION: Continuous intensive isokinetic eccentric training performed with damaged muscles did not exacerbate muscle damage and inflammation after ECC1. In addition, a muscular "adaptation effect" may occur as early as 24 h after ECC1, as shown by the ET group's performance for 6 consecutive days after ECC1.