Eccentric and concentric torque-velocity relationships during arm flexion and extension

Abstract

Forty men were tested with a computerized dynamometer for concentric and eccentric torques during arm flexion and extension at 0.52, 1.57, and 2.09 rad.s-1. Based on the summed concentric and eccentric torque scores, subjects were placed into a high strength (HS) or low strength (LS) group. The eccentric and concentric segments of the torque-velocity curves (TVCs) were generated using peak torque and constant-angle torque (CAT) at 1.57 and 2.36 rad. Angle of peak torque was also recorded. Compared to LS, HS had significantly greater estimated lean body mass (+10.2 kg) and approximately 25% greater average torque output. Reliability of the peak torque scores on 2 days in 20 subjects was r greater than or equal to 0.85. The difference between observed torques and the mathematically computed criterion torque scores averaged 1% for three validation loads that ranged from 11.4 to 90.4 kg. Statistical analysis revealed that torque output in LS plateaued at low concentric velocities and was also flattened with increasing eccentric velocities. Conversely, torque output for HS increased with decreasing concentric velocities and increased with increasing eccentric velocities. The method of plotting the TVCs for peak or CAT did not influence the pattern of TVC. Eccentric flexion peak torque occurred at a significantly shorter muscle length (1.88 rad) than concentric torque (2.12 rad). This difference was also present for extension; it was 1.88 rad for eccentric and 2.03 rad for concentric torque.(ABSTRACT TRUNCATED AT 250 WORDS)

Efeitos do alongamento ativo excêntrico dos músculos flexores do joelho na amplitude de movimento e torque

“…As was stated by Hortobagyi and Katch 30 , concentric torque diminishes with increases of speed, because of the reduction of cross bridges at the highest speeds of muscular shortening, while initially, the opposite occurs during eccentric contractions. In the present study, the increases in eccentric extensor torque were achieved during the performance of the isokinetic test at the lowest speed (30°/s), whereas, during the concentric contractions, the highest extensor speeds were achieved at the speed of 60°/s.…”

Strategies for maximizing power and strength gains in isoinertial resistance training: Implications for competitive athletes

“…1). These curves have been successfully reproduced in human dynamics as the angle-torque-velocity relationship using force transducers or isokinetic devices [24][25][26][27][28][29][30][31][32] . The angle-torque relationship is commonly explained in text books stating that the relative positions of the actin and myosin filaments change as the muscle contracts with the number of effective cross-bridges decreased or optimized 34) .…”

“…It has been well documented that after weeks of isometric or isokinetic training, the strength gain is most promising at the joint angle or velocity of training, with "a transfer of strength gain" being possible near the joint angle or velocity at which the training has been undertaken 5,25,[30][31][32][36][37][38] . The selective adaptations of muscles are proposed to result from specific alterations in the following aspects: 1) morphological (cross sectional area, the number of sarcomeres in series or the pennation angle), 2) neurological (neurotransmitter activity, recruitment patterns of the motor units, agonistantagonist activation or Golgi-tendon organ activity), and 3) biochemical (myosin ATPase activity), to match with the external training stimuli 5,[29][30][31][32][36][37][38][39] . The contributions of Fig.…”

“…In the context of momentum, a faster speed may increase eccentric effort and decrease concentric effort at the end of their respective phases 67,68) . According to the torque-velocity relationship, faster speed may increase effort due to reduced maximum torque ability 29) . Based on the SSC effects, however, faster speed may reduce effort due to enhanced torque or power ability 40,65) .…”

“…For example, suppose a standing dumbbell arm-curl exercise is performed. According to the angle-torque relationship, the torque generating ability of the muscles is weakest near the full extension or flexion of the elbow, but is greatest near 90° flexion 29) . Meanwhile, the perpendicular component of the dumbbell loading to the forearm is very small when the elbow is extended or flexed, while it is largest near 90° flexion.…”