Recent studies indicate that exercise with a low muscle glycogen state enhances exercise-induced metabolic adaptation. However, it is unclear whether metabolic adaptation is involved with muscle glycogen depletion level. In this study, we investigated the effects of prior muscle glycogen depletion level on metabolic response during acute continuous exercise. Seven men completed two experimental trials consisting of two exercise sessions per day. During the first session, participants performed either intermittent exercise (IE) at VO₂max (the IE-CE trial) or continuous exercise (CE) at lactate threshold (the CE-CE trial). During the second session, participants performed 60 minutes of CE at lactate threshold. During this second session, fatty acid oxidation (FAO) was calculated. To determine muscle glycogen content and PGC-1α and PDK-4 mRNA abundance, muscle biopsies were taken at rest after the first session and 2 hours after the second session. After the first session, muscle glycogen content was significantly lower in the IE-CE trial (38.1±5.0 mmol/kg w.w.) than in the CE-CE trial (56.7±10.2 mmol/kg w.w.), P<0.05. FAO was higher in the IE-CE trial than the CE-CE trial at baseline and 15 minutes after the second session (both P<0.05). PGC-1α mRNA abundance increased after exercise (IE-CE, 5.9±2.5; CE-CE, 2.6±1.3-fold; P<0.1). PDK-4 mRNA abundance increased significantly after exercise (IE-CE, 22.2±8.8; CE-CE, 31.5±10.6-fold; P<0.05). PGC-1α and PDK-4 mRNA were not significantly different between the trials. In conclusion, continuous exercise with a slightly muscle glycogen-depleted state induced similar level of PGC-1α and PDK-4 mRNA expression, but attenuated FAO, compared to exercise with a moderate muscle glycogen-depleted state.

Recent health guidelines suggest that children should accumulate 60 minutes of physical activity (PA) of moderate to vigorous intensity every day. The purpose of this study was to assess PA on weekdays, in addition to physical fitness, in elementary school children during short-term extracurricular activities (EA). Children from an elementary school (n=160) who carried out EA were assigned to the EA group, and children from the neighboring elementary school (n=210) comprised the non-EA group. A physical fitness test was applied to evaluate physical fitness in pupils. Moreover, 48 children (EA, n=24; non-EA, n=24) wore a pedometer with a uniaxial accelerometer to determine the amount of PA and time spent in moderate- to vigorous-intensity PA. The PA of EA was evaluated with the exception of the short program (10 min). Jogging distance of the EA was 1357 ± 333 m, average speed was 170 ± 42 m/min. The estimated energy consumption of jogging was 55 ± 19 kcal. Multiple items of the physical fitness test scored significantly higher in the EA group than in non-EA subjects. Total step counts were 15485 ± 1915 steps/day for the EA group and 12363 ± 2464 steps/day for the non-EA group on weekdays (p<0.001). Time spent in moderate- to vigorous-intensity PA on weekdays was 61.6 ± 10.0 min/day for EA children and 46.5 ± 12.9 min/day for non-EA children (p<0.001). In addition, the extent of PA in the EA group was higher than the amount recommended for children in general. This study suggested that short-term EA are related to both the fitness and PA levels of elementary school children.

Angiotensin I converting enzyme (ACE) gene Insertion/Deletion (I/D) polymorphism was first shown as a genetic factor which influences human physical performance in 1998. Since then, various gene polymorphisms which influence physical performance and trainability have been reported. ACE is a key enzyme which produces angiotensin II in the renin-angiotensin system, and its activity was determined by I/D polymorphism. Many studies indicate that the I/I genotype is frequently found in elite endurance athletes, while the D/D genotype is frequently found in power-oriented elite athletes. Longitudinal studies show that the D/D genotype may contribute to enhanced strength trainability. However, it is still unclear whether the I/I genotype enhances endurance trainability. Therefore, the ACE gene I/D polymorphism can be a genetic factor which influences human physical performance.

The decrease of muscle glycogen may be useful for the improvement of endurance performance. Intense anaerobic exercise requires a high rate of glycogen utilization, but consecutive intense anaerobic exercises induce a pronounced decline of external power and muscle glycogen consumption. We hypothesized that a long rest period between consecutive intense anaerobic exercises may aid in sustaining external power and glycogen consumption. Secondly, we hypothesized that active rest (AR) during the long resting period may be more effective than passive rest (PR).Six subjects performed four 30-second Wingate tests (WAnT) with a 4-minute recovery between each bout (Consecutive method). The subjects also performed a similar exercise procedure, but with a 30-minute seated resting period after the second bout (PR method).The other six male subjects performed four 30-second WAnTs with a 4-minute recovery between each bout, with 30-minutes of cycling at 40% VO₂max after the second bout (AR method). The subjects also performed PR method.The total work during the third and fourth bouts was greatest under the AR condition, followed by the PR condition, and finally the Consecutive method (p<0.05 for all comparisons). Blood lactate concentration during resting period was significantly lower, while muscle glycogen consumption was greater AR method than PR method (p<0.05 for both).A long resting period between consecutive intense anaerobic exercises may prevent the decline in external power and work. Additionally, AR has more favorable effects on muscle glycogen consumption, resulting in very low muscle glycogen levels, even with a small total amount of exercise.

In the present study, we instiuted a long-term mild aerobic training program for older patients with hypertension and investigated its effects on serum lipids and lipoprotein concentrations. The intensity of exercise in mild aerobic training was adjusted to the lactate threshold level (LT), i, e., the level at which the blood lactate concentration began to increase nonlinearly with increasing work intensity. The training group (15 patients, 7 men and 8 women) and control group (15 patients, 7 men and 8 women) were 65-83 year-old patients with mean ages of 75.5±5.6 and 73.7±4.4 (mean±S.D), respectively, who had never exercised regularly up to that time. Treadmill training at the LT was carried out for 30min/day 3-6 times/week and continued for 9 months under the supervision of exercise physiology specialists.
In the training group, LT speed significantly increased from 3.43±0.65 km/h to 3.73±0.67 km/h (9.0%) in men, and from 2.75±0.57 km/h to 3.05±0.61 km/h (11.8%) in women (both P<0.05) . HDL-c was significantly increased 9 months after training both in men (19.2%) and women (20.9%) (both P<0.05) . The TC/HDL-c ratio, an atherogenetic index, was significantly (P<0.05) decreased by training in women but not in men. The other serum lipid and lipoprotein profiles were unchanged in both men and women. In the control group, all serum lipid and lipoprotein profiles were unchanged in both men and women.
The HDL-c level in the training group was higher than in the control group after 9 months in both men and women (both P<0.02) . The TC/HDL-c ratio in the training group was lower only in women (P<0.02) . There were no significant differences in other values between the training group and the control group in either men or women.
These results suggest that mild aerobic training at the LT is an effective method of improving the level of serum HDL-c, the TC/HDL-c ratio and aerobic capacity in the older patients with hypertension.

After a general clinical observation period of 3 months, men and women from 66-82 yr. of age with hypertension (n=10) were studied to assess the effects of long-term mild aerobic training and detraining on their blood pressure. Ten patients agreed to take part in aerobic training using a treadmill with the intensity at the lactate threshold (LT) for 30minutes 3-6 times a week for mean 17.1±9.8 months while the time course of changes in the resting blood pressure was monitored.
Following the training period the LT increased significantly by the end of the training period (P<0.001) . After 3months of training both the systolic and diastolic blood pressure decreased significantly (P<0.05, respectively) and both blood pressures stabilized at a significantly lower level throughout the remainder of the study. The mean blood pressure decreased significantly for 9 months (P<0.05) . Finally, the systolic, mean and diastolic blood pressure were found to have decreased significantly, by 9, 5, 11 mmHg, respectively by the end of the training period. (SBP and MBP: P<0.05, DBP: P<0.01, respectively) . One month after the training ended the systolic, mean and diastolic blood pressure all increased significantly (SBP and MBP: P<0.001, DBP: P<0.01, respectively) and approached the initial pre-training levels.
In conclusion, the antihypertensive effect of mild aerobic training at the LT was confirmed for older patients taking antihypertensive medications. However, the cessation of such training resulted in a quick return to pre-training levels.

The effects of long-term low intensity aerobic training and detraining on serum lipid and lipoprotein concentrations were examined in 10 older patients suffering from hypertension and coronary heart disease. Training was carried out for 30 minutes 3-6 times a week for a mean of 17.1 months using a treadmill with the intensity level set at the blood lactate threshold (LT) .
Following this training both LT and the serum HDL-c increased significantly (P<0.001, P<0.01, respectively) after 6 months while the TC/HDL-c ratio decreased singificantly (P<0.001) only after 1 month and stabilized at a steady favorable value throughout the remainder of the study. The serum TC, TG and LDL-c did not change significantly by the end of the training period. There was a significant negative correlation between the initial TC/ HDL-c level and the change in the TC/HDL-c level at 1 month after training (r=-0.71, P< 0.02) . Only 1 month after the detraining the HDL-c decreased significantly while the TC/HDL-c increased in comparison with the final training value (P<0.001, P<0.05, respectively) and then returned to the pre-training levels.
In conclusion, these results suggest that long-term low intensity aerobic training could improve the profile of the serum lipid and lipoprotein concentrations in older patients. However, these results might depend on such factors as a low HDL-c level, a high TG level, the length of the exercise period, or the frequency per week and the age of the patient, while the cessation of such training quickly returned the profile to that of pre-training levels.

This study sought to determine whether aerobic exercise training affects cognitive functioning among semi-independent (> 75 years) and independent elderly people. Seventy-six semi-independent and independent elderly subjects were divided into the following groups: semi-independent control (n = 16); semi-independent training (n = 13); independent control (n = 22); independent training (n = 25). During the 12-week intervention, subjects in both training groups performed a bench-stepping exercise at the intensity of the lactate threshold. Subjects were assessed at baseline and post-intervention using the Frontal Assessment Battery test (FAB), the Modified Mini-Mental State Exam (3MS), and a bench-stepping test of aerobic capacity. During the intervention, FAB scores improved only in the semi-independent training group (p = .002), while 3MS and MMSE scores improved in both the semi-independent training (p = .032 and p = .004) and independent training groups (p = .001 and p = .013). FAB and 3MS scores were higher in the semi-independent training (p = .001 and p = .002) compared with the semi-independent control group after the intervention. Finally, post-intervention scores for FAB, and 3MS in the semi-independent training group almost reached the baseline levels of the independent control and independent training groups. These results indicate that moderate intensity bench-stepping exercise training can improve cognitive and frontal lobe functioning in semi-independent elderly people, almost to the level exhibited by independent elderly people.

Double product (DP, heart rate × systolic blood pressure) during an incremental exercise test has been known to start to increase steeply at a workload, i. e. double product break point (DPBP), which corresponds to the blood lactate threshold. The study was to investigate the relationship between DP transition and ST segment depression in electrocardiogram during exercise. Thirty-one patients of angina pectoris of effort and 140 elderly persons performed a continuous incremental exercise test using a stationary bicycle ergometer. During the entire test, HR and blood pressure were measured every 15 seconds and an electrocardiogram was recorded continuously. DPBP was then calculated. In ten of the 31 patients, ST level depression above -0.1 mV with a typical ischemic form in lead V 5 was observed during the test. However, workload at the DPBP was significantly lower than that of the ischemic threshold on the electrocardiogram (i. e. -0.1mV of ST depression) in relation to work load (46+/-16 vs. 78+/-20 watts), HR (96+/-13 vs. 117+/-13 bpm), SBP (160+ /-20 vs. 199+/-31 mmHg) and DP (15400+/-3400 vs. 23400+/-4900 bpm × mmHg) . In elderly persons, DPBP could be determined without the ischemic ST depression in 96% of 327 tests. This study indicated that the DPBP would be an objective index of exercise intensity with lower risk for exercise prescription in cardiac patients and elderly persons.