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Rodrigo de M. Baldon, Leonardo Furlan and Fábio V. Serrão

The purpose of this study was to verify the influence of the hip flexion angle on isokinetic rotator torque and acceleration times of the hip medial and lateral rotator muscles. Twenty-one healthy women were included in this study. The hip rotator function was evaluated at 3 different hip flexion angles (10°, 40°, and 90°). The results showed that both eccentric and concentric hip lateral rotator torques were greater at 40° of hip flexion when compared with 90°. Moreover, both the eccentric and concentric hip medial rotator torques were greater at 90° of hip flexion than at 40° and 10°, and greater at 40° than at 10°. In addition, both the eccentric and concentric hip medial to lateral rotator torque ratios were greater at 90° of hip flexion than at 40° and 10°, and greater at 40° than at 10°. Finally, the acceleration times of the hip medial rotator muscles were smaller at 90° of hip flexion than at 10° and smaller at 40° than at 10°. The current results highlight the importance of evaluating the hip rotator muscles at different hip flexion angles to comprehensively assess their functions.

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Kentaro Chino, Naotoshi Mitsukawa, Kai Kobayashi, Yusuke Miyoshi, Toshiaki Oda, Hiroaki Kanehisa, Tetsuo Fukunaga, Senshi Fukashiro and Yasuo Kawakami

To investigate the relationship between fascicle behavior and joint torque, the fascicle behavior of the triceps surae during isometric and eccentric (30 and 60 deg/s) plantar flexion by maximal voluntary and submaximal electrical activation (MVA and SEA) was measured by real-time ultrasonography. Eccentric torque at 30 and 60 deg/s was significantly higher than isometric torque under SEA, but not under MVA. However, fascicle length did not significantly differ between isometric and eccentric trials under either condition. Therefore, the difference in developed torque by MVA and SEA cannot be explained by fascicle behavior. Under both MVA and SEA conditions, eccentric torque at 30 and 60 deg/s was equivalent. Similarly, fascicle lengthening velocities at 30 and 60deg/s did not show any significant difference. Such fascicle behavior can be attributed to the influence of tendinous tissue and pennation angle, and lead to a lack of increase in eccentric torque with increasing angular velocity.

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Yanita McLeay, Stephen R Stannard, Toby Mundel, Andrew Foskett and Matthew Barnes

This study was designed to investigate the effects of alcohol consumption on recovery of muscle force when consumed immediately postexercise in young females. Eight young women completed 300 maximal eccentric actions of the quadriceps femoris muscle on an isokinetic dynamometer on two occasions in a randomized, cross-over design after which an alcoholic beverage (0.88g ethanol/kg body weight) or an iso-caloric placebo was consumed. Maximal isokinetic (concentric and eccentric) torque and isometric tension produced across the knee were measured in both the exercised and control leg predamage, 36 hr post, and 60 hr post damage. Venous blood creatine kinase (CK) activity and muscle soreness ratings were taken before damage and once per day to 60 hr post damage. Significant differences were observed between the exercised and control leg for maximal concentric, and eccentric torque and isometric tension (p < .05). A near significant Treatment × Time interaction was observed for isometric tension (p = .077), but not for concentric or eccentric torque. No main effects of treatment (alcohol) or interactions with Time × Leg or Leg × Treatment were observed. Perceived muscle soreness during box stepping and squatting showed significant time effects (p < .05), and CK activity did not significantly change. Our results indicate that the consumption of 0.88g ethanol/kg body weight following eccentric exercise-induced muscle damage does not affect recovery in the days following damage in females.

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Clayton L. Camic, Terry J. Housh, Jorge M. Zuniga, Haley C. Bergstrom, Richard J. Schmidt and Glen O. Johnson

The purpose of the current study was to examine the patterns of responses for torque, mechanomyographic (MMG) amplitude, MMG frequency, electromyographic (EMG) amplitude, and EMG frequency across 30 repeated maximal eccentric muscle actions of the leg extensors. Eleven moderately trained females performed an eccentric fatigue protocol at 30°/s with MMG and EMG signals recorded from the vastus lateralis. The results indicated there were significant (P < .05) decreases in MMG frequency (linear, r 2 = .395), EMG frequency (linear, r 2 = .177), and torque (linear, r 2 = .570; % decline = 9.8 ± 13.3%); increases in MMG amplitude (linear, r 2 = .783); and no change in EMG amplitude (r 2 = .003). These findings suggested that the neural strategies used to modulate torque during fatiguing eccentric muscle actions involved de-recruitment of motor units, reduced firing rates, and synchronization. In addition, the decreases in eccentric torque were more closely associated with changes in MMG frequency than EMG frequency. Thus, these findings indicated that MMG frequency, compared with EMG frequency, more accurately tracks fatigue during repeated maximal eccentric muscle actions.

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Daniel D. Cohen, Bingnan Zhao, Brian Okwera, Martyn J. Matthews and Anne Delextrat

Purpose:

To evaluate the effect of simulated soccer on the hamstrings eccentric torque-angle profile and angle of peak torque (APTeccH), and on the hamstrings:quadriceps torque ratio at specific joint angles (ASHecc:Qcon).

Methods:

The authors assessed dominant-limb isokinetic concentric and eccentric knee flexion and concentric knee extension at 120°/s in 9 semiprofessional male soccer players immediately before and after they completed the Loughborough Intermittent Shuttle Test (LIST).

Results:

The LIST resulted in significant decreases in eccentric hamstrings torque at 60°, 50°, and 10° and a significant (21.8%) decrease in ASHecc:Qcon at 10° (P < .05). APTeccH increased from 7.1° ± 1.0° to 18.8° ± 4.2° (P < .05). Eccentric hamstrings peak torque significantly declined from 185.1 ± 70.4 N·m pre-LIST to 150.9 ± 58.5 N·m post-LIST (P = .002), but there were no significant changes in hamstrings or quadriceps concentric peak torque (P = .312, .169, respectively).

Conclusions:

Simulated soccer results in a selective loss of eccentric hamstrings torque and hamstrings-to-quadriceps muscle balance at an extended joint position and a shift in the eccentric hamstrings APT to a shorter length, changes that could increase vulnerability to hamstrings injury. These findings suggest that injury-risk screening could be improved by evaluating the eccentric hamstrings torque-angle profile and hamstrings strength-endurance and that the development of hamstrings fatigue resistance and long-length eccentric strength may reduce injury incidence.

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Chariklia K. Deli, Ioannis G. Fatouros, Vassilis Paschalis, Kalliopi Georgakouli, Athanasios Zalavras, Alexandra Avloniti, Yiannis Koutedakis and Athanasios Z. Jamurtas

Purpose:

Research regarding exercise-induced muscle-damage mainly focuses on adults. The present study examined exercise-induced muscle-damage responses in adults compared with children.

Method:

Eleven healthy boys (10–12 y) and 15 healthy men (18–45 y) performed 5 sets of 15 maximal eccentric contractions of the knee extensors. Range of motion (ROM), delayed onset muscle soreness (DOMS) during squat and walking, and peak isometric, concentric and eccentric torque were assessed before, post, 24, 48, 72, and 96 hr postexercise. Creatine kinase (CK) activity was assessed before and 72 hr postexercise.

Results:

Eccentric exercise resulted in DOMS during squat that persisted for up to 96h in men, and 48 hr in boys (p < .05), and DOMS during walking that persisted for up to 72 hr in men, and 48 hr in boys (p < .01). The ROM was lower in both age groups 48 hr postexercise (p < .001). Isometric (p < .001), concentric (p < .01) and eccentric (p < .01) force decreased post, and up to 48 hr postexercise in men. Except for a reduction in isometric force immediately after exercise, no other changes occurred in boys’ isokinetic force. CK activity increased in men at 72 hr postexercise compared with pre exercise levels (p = .05).

Conclusion:

Our data provide further confirmation that children are less susceptible to exercise-induced muscle damage compared with adults.

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Özlem Aslan, Elif Balevi Batur and Jale Meray

evaluated, it was found that there was a good correlation between Hecc/Qcon torque ratios and stair-climbing time, and between Hcon/Qecc torque ratios and descending stairs time at 60° and 120° per second velocities. In addition, they found hamstring eccentric torques and Hcon/Qecc torque ratios (as

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Richard A. Brindle, David Ebaugh and Clare E. Milner

. Boling MC , Padua DA , Alexander Creighton R . Concentric and eccentric torque of the hip musculature in individuals with and without patellofemoral pain . J Athl Train . 2009 ; 44 : 7 – 13 . PubMed ID: 19180213 doi:10.4085/1062-6050-44.1.7 10.4085/1062-6050-44.1.7 19180213 2. Hewett TE

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Mark De Ste Croix, Abigail Priestley, Rhodri Lloyd and Jon Oliver

studies appear to have calculated the H/Q FUNC using functionally relevant procedures ( 4 ). One study exploring the effects of fatigue on concentric and eccentric muscle actions suggest that eccentric torque production is more fatigue resistant than concentric torque production ( 26 ); thus, the H

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Eduardo Lusa Cadore, Miriam González-Izal, Rafael Grazioli, Igor Setuain, Ronei Silveira Pinto and Mikel Izquierdo

GECC showed increases in the mean concentric torque during the first four 10-repetition intervals (ie, first and second halves of the first and second sets; P  < .01). In addition, GECC showed increases in the mean eccentric torque during all 10-repetition intervals (all P s < .001), whereas GCON