Glycogen is an important source of energy production during endurance exercise, such as marathon. Due to limited storage of glycogen in muscle and liver, augmentation of fat oxidation is known to delay depletion of muscle glycogen, leading to improvement of endurance performance. N-3 polyunsaturated fatty acids (n-3 PUFA) resulting from the form of fish has shown to enhance fat oxidation at rest. However, effect of n-3 PUFA on substrate metabolism during prolonged exercise remains unclear. The present study was designed to investigate whether dietary n-3 PUFA enhances fat oxidation during exercise and endurance performance. Thirteen healthy men were divided into n-3 PUFA group [n=6, 6g/day of fish oil; 1,800mg eicosapentaenoic acid (EPA), 2,700mg docosahexiaenoic acid (DHA)] or CON group [n=7, 6g/day of olive oil]. The subjects ingested each supplement for 4-weeks. Before and after the treatment period, a 60-min pedaling exercise at 65% of maximal oxygen uptake followed by 5 km-time-trial was conducted. Resting concentrations of serum EPA and DHA, EPA/AA were significantly elevated in the n-3 PUFA group only. After supplementation period, the n-3 PUFA group increased significantly exercise-induced elevations of serum free fatty acids and glycerol concentrations, and lowered respiratory exchange ratio during a 60-min pedaling exercise. Similar changes were not observed in the CON group. However, treatment with n-3 PUFA did not affect significantly result of 5km-time-trial. Four-week supplementation of n-3 PUFA increased exercise-induced lipolysis and fat oxidation during prolonged exercise. However, the augmented fat metabolism did not affect endurance performance.
Recently, the problem of the high incidence of throwing injuries in young people has been gaining attention. Identifying high-risk players before the onset of the throwing injury is important for prevention. One of the most widely used screening tests for sports-related injuries is the Functional Movement Screen (FMS), which assesses the quality of movement; however, its correlation with throwing injuries has not been established. The purpose of this study was to investigate the correlation between the FMS score and throwing injuries. The FMS was used during the medical check for two hundred and thirty junior high school baseball players. We allotted those who had experienced throwing injuries multiple times to the injury group and those who had never experienced throwing injury to the control group. We then calculated the FMS cutoff value using the receiver operating characteristic curve. In addition, we investigated differences in the incidence of throwing injury between above and below the cutoff value using chi-square test. The FMS cutoff score was 17. Players who scored ≤17 had a significantly higher incidence of throwing injuries than those who scored ≥18. Conclusion: We believe that FMS score is correlated to throwing injuries. In addition, the results suggest that throwing injuries might be prevented in junior high school baseball players who scored ≤17 on the FMS if they undergo training in the correct movement patterns.
The purpose of this study was to identify the ground reaction force and lower extremity joint kinetics during clean exercises performed with light and heavy loads. Thirteen male track and field athletes performed the clean exercises from 20 kg to one repetition maximum (1RM). Kinetic data were collected from recorded data using a Vicon motion system (250 Hz) and force platforms (1,000 Hz). The results of the analyses were as follows: (1) Ground reaction force and joint kinetics of hip and ankle were increased by increasing loads in clean exercises. (2) From light to heavy loads, we found relationships between ground reaction force and joint torque of hip in clean exercises. (3) In progressing from light to heavy loads, some subjects continued to involve the muscle group controlling the hip joint as the main power source, while others did not. The results indicate that clean exercises yield different individual characteristics for training. These results suggest that the clean exercise is effective for selectively the hip extensor in all loads.
We used a randomized controlled trial and examined the effectiveness of a 3-month, home based, exercise program to the functioning in older Japanese adults. Following the intervention, we also conducted 3- and 6-month follow-up studies of physical functioning and exercise adherence. Participants were older adults (n = 32, 16 males and 16 females, age over 75 years). They were randomly divided into exercise and control groups. The Tokyo Metropolitan Institute of Gerontology Index of Competences, the Mini-Mental State Examinations, as well as physical fitness tests assessing grip strength, maximum step length, 10 m walking speed, and standing on one leg with eyes open were administered to the participants. Moreover, home visit instructions were given biweekly. Participants worked out at home on 3 days a week. Analyses of variance indicated that the intervention group significantly increased their maximum step length and time standing on one leg with eyes open, although there were no significant changes in the other tests. Result of follow-up investigations indicated that maximum step lengths at 3- and 6-months after the intervention were 69.9 and 68.8 cm respectively, which was less than immediately after the intervention (70.6 cm), but significantly higher than before the intervention (65.8 cm). Moreover, the effect of the intervention on standing on one leg with eyes open was maintained at the 6-month follow-up. Furthermore, percentages of participants that exercised more than one day per week 3- and 6 months after the intervention were 87 % and 81 % respectively, which was significantly higher than before the intervention (44 %). These results suggest that the home-based exercise program was effective in promoting adherence for a period of 6-months.
The purpose of this study was to investigate the association between activity levels assessed by a uniaxial accelerometer and metabolic equivalents (METs) during walking and running in school students. The participants were elementary (10 boys, 10.3 ± 0.8 years), middle (10 boys, 13.0 ± 0.9 years) and high school students (10 boys, 15.7 ± 0.7 years) who performed treadmill walking (1, 3, and 5 km/h respectively) and running (5, 7, and 9 km/h respectively) trials. Activity levels were assessed using a uniaxial accelerometer (Lifecorder EX; Suzuken Co. Ltd., Nagoya, Japan). Energy expenditure was measured by indirect calorimetry. METs and activity levels indicated by Lifecorder were highly correlated in elementary (y = 0.0432x2 + 0.0914x + 1.786, r = 0.883, p < 0.05), middle (y = 0.0781x2 - 0.0262x + 2.1098, r = 0.913, p < 0.05), and high (y = 0.0516x2 + 0.1863x + 1.7812, r = 0.876, p < 0.05) school students. We confirmed that higher accuracy showed LC5, LC4, and LC4 for elementary, middle, and high school students, respectively. In conclusion, this study suggests that Lifecorder intensity for ≥3 METs physical activity indicate ≥5, ≥4, and ≥4 for elementary, middle, and high school students, respectively.