• Equal volumes of high and low intensity of eccentric exercise in relation to muscle damage and performance.

      Paschalis, Vassilios; Koutedakis, Yiannis; Jamurtas, Athanasios Z.; Mougios, Vassilis; Baltzopoulos, Vassilios (Human Kinetics Publishers, Inc., 2005)
      We examined differences in muscle damage and muscle performance perturbations in relation to the same volumes of high (HI) and low intensity (LI) of eccentric exercise. Untrained young healthy men (n = 12) underwent 2 isokinetic quadriceps eccentric exercise sessions, 1 on each randomly selected leg, separated by a 2-week interval. In the first session subjects performed HI exercise (i.e., 12 sets of 10 maximal voluntary efforts). In the second session, volunteers were subjected to continuous exercise of LI (50% of peak torque) until the total work done was approximately equal to that generated during HI. Muscle damage (serum creatine kinase concentration [CK], delayed onset of muscle soreness, and range of motion) and muscle performance (eccentric [EPT] and isometric peak torque [IPT]) indicators were assessed pre-exercise and 24, 48, 72, and 96 hours postexercise. Compared to baseline data, changes in muscle damage indicators were significantly different (p < 0.05) at almost all postexercise time points in both conditions. However, apart from the significant elevation of CK at 24 hours after HI (p < 0.05), no other significant differences were observed between the 2 exercise conditions (p > 0.05). The main finding in relation to muscle performance was that decrements following HI exercise were significantly greater (p < 0.05) compared to LI. Compared with baseline data, the EPT values following HI and LI exercise were as follows: 24 hours, 72.1% vs. 92%; 48 hours, 81.9% vs. 94.8%; 72 hours, 77.7% vs. 100.6%; 96 hours, 86.8% vs. 107.9%. The corresponding data for IPT were as follows: 24 hours, 86.4% vs. 102.8%; 48 hours, 84.2% vs. 107%; 72 hours, 84.8% vs. 109.2%; 96 hours, 86.8% vs. 114.4%. These results indicate that matching volumes of HI and LI eccentric exercise have similar effects on muscle damage, but HI has a more prominent effect on muscle performance.
    • Isokinetic characteristics of knee flexors and extensors in male dancers, olympic oarsmen, olympic bobsleighers, and non-athletes

      Koutedakis, Yiannis; Agrawal, Arvind; Sharp, N. C. Craig (J. Michael Ryan, 1998)
      Quadriceps (PTQUAD) and hamstring (PTHAM) concentric peak torques — measured in Nm and Nm·kg-1 body weight — and hamstring/quadriceps peak torque ratios (PTHAM/QUAD) were studied in males engaged in different physical activities and having different levels of physical fitness. Both dominant and non-dominant legs of 20 professional dancers, 14 Olympic oarsmen, 11 Olympic bobsleighers, and 10 non-athletes were isokinetically assessed at 1.04, 3.14, and 4.19 rad·sec-1. The main findings were: 1. torque levels decreased with increasing angular velocity in all four groups of subjects; 2. with few exceptions, dancers and non-athletes demonstrated significantly lower PTQUAD and PTHAM (p < 0.01 to p < 0.005) at the three velocities than bobsleighers and rowers; 3. most of the differences between groups described above, disappeared (p > 0.05) when PTQUAD and PTHAM were standardized for body weight (Nm·kg-1); and 4. although PTHAM/QUAD for dancers and non-athletes were significantly lower than that of the two sports groups at 1.04 and 3.14 rad·sec-1, no such differences were noted at the relatively higher velocity of 4.19 rad·sec-1. We conclude that dissimilar physical training, modes of exercise, and/or different fitness levels have the same effect on muscle contractile characteristics.