Effects of Unilateral Eccentric versus Concentric Training of Nonimmobilized Arm during Immobilization

Abstract

IntroductionThe present study tested the hypothesis that eccentric training (ET) of nonimmobilized arm would attenuate negative effects of immobilization and provide greater protective effects against muscle damage induced by eccentric exercise after immobilization, when compared with concentric training (CT).MethodsSedentary young men were placed to ET, CT, or control group (n = 12 per group), and their nondominant arms were immobilized for 3 wk. During the immobilization period, the ET and CT groups performed five sets of six dumbbell curl eccentric-only and concentric-only contractions, respectively, at 20%–80% of maximal voluntary isometric contraction (MVCiso) strength over six sessions. MVCiso torque, root-mean square (RMS) of electromyographic activity during MVCiso, and bicep brachii muscle cross-sectional area (CSA) were measured before and after immobilization for both arms. All participants performed 30 eccentric contractions of the elbow flexors (30EC) by the immobilized arm after the cast was removed. Several indirect muscle damage markers were measured before, immediately after, and for 5 d after 30EC.ResultsET increased MVCiso (17% ± 7%), RMS (24% ± 8%), and CSA (9% ± 2%) greater (P < 0.05) than CT (6% ± 4%, 9% ± 4%, 3% ± 2%) for the trained arm. The control group showed decreases in MVCiso (−17% ± 2%), RMS (−26% ± 6%), and CSA (−12% ± 3%) for the immobilized arm, but these changes were attenuated greater (P < 0.05) by ET (3% ± 3%, −0.1% ± 2%, 0.1% ± 0.3%) than CT (−4% ± 2%, −4% ± 2%, −1.3% ± 0.4%). Changes in all muscle damage markers after 30EC were smaller (P < 0.05) for the ET and CT than the control group, and ET than the CT group (e.g., peak plasma creatine kinase activity: ET, 860 ± 688 IU·L−1; CT, 2390 ± 1104 IU·L−1; control, 7819 ± 4011 IU·L−1).ConclusionsThese results showed that ET of the nonimmobilized arm was effective for eliminating the negative effects of immobilization and attenuating eccentric exercise–induced muscle damage after immobilization.

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“…Previous studies have observed this effect for upper and lower extremity muscles, and single limb eccentric resistance training appears to have a greater cross-sectional effect than concentric resistance training. In the July issue of Medicine & Science in Sports & Exercise ® ( MSSE ), Chen and colleagues (1) from Taiwan evaluated the impact of single arm eccentric and concentric training on an immobilized contralateral arm not only on measures of muscle size and strength, but also on the amount of muscle damage and delayed muscle soreness that occurs when resistance training is resumed after immobilization.…”

Contralateral versus ipsilateral protective effect against muscle damage of the elbow flexors and knee extensors induced by maximal eccentric exercise

“…Participants were in a seated position for the EF exercise and in a prone position for the knee flexor exercise. 2,12 Each contraction lasted for 3 s and was repeated every 10 s, and a 2-min rest was given between sets. After each contraction, the isokinetic dynamometer passively brought the participant's limb back to the flexed position at the angular velocity of 9°/s, which provided a 10-s rest between contractions.…”

“…3 MVC torque of the KF and knee extensors (KE) was measured using the same isokinetic dynamometer in the same position as that described for the exercise, at an angular velocity of 60°/s for the range of motion of 120° for the KF (0°-120°) and the KE (120°-0°) for three continuous contractions for both directions. 9,12 The EE and KE MVC torque measures were included to examine the effect of the eccentric exercise on antagonist muscles. Verbal encouragement was provided during each test.…”

“…The biceps brachii muscle hardness was measured as each participant lay supine with the testing arm was extended and relaxed on an exam table. 12 The biceps femoris muscle hardness was measured as each participant lay prone with the testing leg extended and relaxed on an exam table. 3 The algometer quantified the amount of tissue displacement applied by the probe onto the site.…”

“…Based on our previous studies 2,12 showing that 2 days postexercise time point or peak changes reflected the magnitude of the repeated bout effect better, and the magnitude of the protective effect (index of protection) was calculated using the values at 2 days post-exercise for MVC torque and ROM, and peak values for other measures by the following equation: (EC1 -EC2)/EC1 × 100. 2 For example, if the responses were the same between EC1 and EC2, it was considered as no protection (the index is 0%), and an index of 50% would show that the changes in the dependent variables were 50% smaller after EC2 than EC1.…”