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Power and strength changes following a bout of concentric or eccentric leg press exercise
Author
Chew, Kia Seng
Supervisor
Quigley, Brian M.
Schmidt, Gordon J.
Abstract
Eccentric muscular actions occur as a result of muscles lengthening during contraction. Previous studies involving such muscular activities have focused on aspects like delayed onset muscle soreness (DOMS), enzyme activity, electrically stimulated muscle characteristics, muscle fibre damage and neuromuscular adaptations (MacIntyre et al., 1995). Although these studies measure physiological components and strength changes, not many researchers have evaluated changes in power after a single intense exercise session.
The present study was designed to measure strength and power following an acute bout of isolated concentric or eccentric leg press exercise. Twenty four subjects (mean age + SD= 23.9 t1.7 years) from the School of Physical Education, Nanyang Technological University were randomly assigned into three groups (n=8). The concentrically exercised (CON) and eccentrically exercised (ECC) groups performed a leg press exercise consisting of 3 sets of 12 repetitions of their maximum isometric strength determined by a modified dynamometer device. Power tests consisted of countermovement jumps (CMJ) and squat jumps (SJ) measured on a force plate, and strength was assessed using isometric leg press dynamometry. Additionally, average peak power and total work on a cycle ergometer for 10 seconds were measured pre-exercise and nine times post exercise. Muscle soreness measurements were made six times pre- and post exercise.
Results revealed greater strength decrements for ECC than CON throughout the study. CMJ heights for both groups show no significant difference (p<.01) and were below baseline even after 48h. SJ heights decreased less than CMJ heights and recovered to baseline by 24h. In peak power and total work, CON recovered to baseline by 2h compared to ECC who recovered by 24h. There was no indication of muscle soreness or DOMS.
Further research needs to be carried out in the area of power changes related to different exercise intensities and muscle groups. Studies should also be designed to examine the relationship of force and velocity in power generation following acute exercise.
The present study was designed to measure strength and power following an acute bout of isolated concentric or eccentric leg press exercise. Twenty four subjects (mean age + SD= 23.9 t1.7 years) from the School of Physical Education, Nanyang Technological University were randomly assigned into three groups (n=8). The concentrically exercised (CON) and eccentrically exercised (ECC) groups performed a leg press exercise consisting of 3 sets of 12 repetitions of their maximum isometric strength determined by a modified dynamometer device. Power tests consisted of countermovement jumps (CMJ) and squat jumps (SJ) measured on a force plate, and strength was assessed using isometric leg press dynamometry. Additionally, average peak power and total work on a cycle ergometer for 10 seconds were measured pre-exercise and nine times post exercise. Muscle soreness measurements were made six times pre- and post exercise.
Results revealed greater strength decrements for ECC than CON throughout the study. CMJ heights for both groups show no significant difference (p<.01) and were below baseline even after 48h. SJ heights decreased less than CMJ heights and recovered to baseline by 24h. In peak power and total work, CON recovered to baseline by 2h compared to ECC who recovered by 24h. There was no indication of muscle soreness or DOMS.
Further research needs to be carried out in the area of power changes related to different exercise intensities and muscle groups. Studies should also be designed to examine the relationship of force and velocity in power generation following acute exercise.
Date Issued
1996
Call Number
GV481 Che
Date Submitted
1996