ABSTRACT
The purpose of this study was to examine the recruitment state of synergistic muscles in the thigh muscles in leg press exercise with and without pre-fatigue method using transverse relaxation time (T2) on muscle functional magnetic resonance imaging (MRI). Nine healthy male subjects performed the following two types of exercise trials on separate days: 1) 5 sets of a leg press exercise with pre-fatigue method, which consisted of 3 sets of knee extension exercise (LP-pre), 2) 5 sets of a leg press exercise without pre-fatigue method (LP). Both exercises were performed at a load of 80% one-repetition maximum. Before and immediately after exercise, T2-weighted MR images of right-thigh were taken to calculate T2 values of twelve-thigh muscles. The T2 values for quadriceps femoris muscle and hamstrings in LP increased significantly after the exercise, except in the adductor magnus, adductor longus, gracilis, and sartorius. In contrast, the T2 values for all of the twelve-thigh muscles in LP-pre increased significantly after the exercise. Upon comparison between the two trials, the percentage changes in T2 value for the adductor magnus, adductor longus, and sartorius in LP-pre were found to be significantly greater than those in LP. These results suggest leg press exercise with pre-fatigue method may be effective to increase activity of synergistic muscles in thigh muscles during exercise.
ABSTRACT
The purpose of present study was to investigate the cerebral oxygenation and oxygen uptake (VO<sub>2</sub>) during exercise of a combined circuit training (CCT) and a circuit resistance training (CRT). Nine healthy young male subjects performed the following two trails on separate days: 1) CCT trail (three circuits of aerobic exercise for 5 min at 50%VO<sub>2</sub>max and 1 set of four resistance exercises at 50% one-repetition maximum) and 2) CRT trail (six circuits of the same resistance exercises and intensity as for CCT without aerobic exercise). Exercise duration of these trails was 30 minutes. Cerebral oxygenation was determined by near infrared spectroscopy, and VO<sub>2</sub> was measured by breath by breath methods. Cerebral oxygenation and VO<sub>2</sub> were continuously monitored during the exercise. Oxyhemoglobin and total hemoglobin concentration during CCT trail was significantly higher than during CRT trail (<i>p</i><0.05). Average VO<sub>2</sub> and energy expenditure during CCT trail were significantly higher than during CRT trail (<i>p</i><0.05). These results suggest that a single bout of circuit resistance training combined with aerobic exercise induced greater energy expenditure and cerebral oxygenation than those induced by a resistance training with the same exercise duration.
ABSTRACT
The purpose of this study was to investigate the acute effects on excess post-exercise oxygen consumption (EPOC) of low intensity and slow-movement repetitive resistance exercise in moderately trained young men. Seven healthy trained young men (age=22±3 yr ; height=172.5±4.0 cm ; weight=69.5±8.3 kg ; VO<sub>2</sub>max=47.3±6.0 ml/kg/min) performed the following three exercise patterns on separate days : 1) high-intensity (80% one-repetition maximum : 1RM) and regular-movement repetitive exercise (1 second each of concentric and eccentric action, termed high and regular exercise (HRE) ; 2) low-intensity (50%1RM), regular-movement repetitive exercise (same movement speed as for HRE but termed low and regular exercise (LRE); and 3) low-intensity (50%1RM), slow-movement repetitive exercise (4 sec each of concentric and eccentric action, termed low and slow exercise (LSE). These three exercise patterns consisted of three sets of four exercises performed to maximum repetition. All subjects completed the three exercise sessions in a randomized and counterbalanced fashion. Oxygen consumption (VO<sub>2</sub>) and heart rate (HR) were continuously monitored during the exercise sessions and for 90 min afterwards. EPOC over 90 min was thus observed after completing the three exercise patterns. However, there were no significant differences in EPOC among the three exercise patterns. The results of this study suggest that low-intensity and slow-movement repetitive resistance exercise with maintaining muscular tension (LSE) is likely to increase EPOC to the same extent as HRE and LRE exercise patterns.
ABSTRACT
15 healthy elderly adults (68.6±4.5 years old) participated in this study and were chosen at random for either super low-velocity repetition training (SLT : n=7) or general low-velocity repetition training (GLT : n=8). All subjects performed machine training leg work twice a week for 6 months. Training contents of SLT and GLT were programmed as follows : SLT (Method : 4 seconds of lifting and 6 sec of lowering) and GLT (Method : 2 sec of lifting and 2 sec of lowering). Muscular strength testing was adopted during isometric knee extension using Cybex6000, and body composition was measured by DXA method. As a result, increases in peak torque values and 5 sec average torques value were significantly different in both groups, pre- and post-training (p<0.05). However, there was no significant difference between the two groups. Fat mass significantly decreased during post-training in both groups (p<0.05); however, there was no significant difference between the groups. SLT showed that increases in maximum muscular strength and endurance were similar to GLT. Thus, low-intensity and low-velocity repetition training is suggested as an effective method for elderly adults to increase lower limb muscular strength.