Association between breakfast dietary patterns and physical activity in Japanese fifth- and sixth-grade elementary school children / 体力科学

This study aimed to explore the association of breakfast (BF) dietary patterns with physical activity (PA) and fitness in elementary school children. This study enrolled 242 school children of 5th and 6th grade. BF dietary patterns were evaluated by questionnaires on whether the child consumes the following food categories: staple, main dish, side dish, soup, milk or dairy products, and fruit. Individual PA levels were categorized into high and low PA groups using a PA scale for children. The measured 8 assessments of physical fitness scores were converted to Z-scores normalized for sex, age and height as previously reported. High PA group had significantly higher scores in running and muscle strength as well as in the total score of physical fitness. The frequency of eating BF (with or without BF omission) and the level of PA were not significantly related in both sexes. However, in girl children, BF, including staple, main dish, side dish, and soup, was significantly more prevalent in high PA group than low PA group (55.9% vs. 32.1%; χ2 = 5.638, p = 0.018). A similar tendency was observed in girls who had BF, including staple, main dish, and side dish (49.0% vs. 31.1%; χ2 = 3.720, p = 0.054). No associations between dietary patterns and PA were observed in boys. The results suggested that the frequency of eating BF was not associated with PA levels, which was significantly related to physical fitness in Japanese 5th and 6th grade elementary school children. In contrast, the results indicated that a high-quality BF dietary pattern, such as a meal including staple, main dish, side dish, and soup, might be associated with a physically active girl child.

Association between various levels of training-related energy expenditure and dietary and nutrient intake in Japanese male collegiate rugby players / 体力科学

This study aimed to explore the association between various levels of training-energy expenditure (TrEE) and nutritional response during the phases of periodization among male collegiate rugby players. Seventeen Japanese male collegiate rugby players were enrolled in the study. Their TrEE and dietary intake were assessed each day during three separate microcycle training phases in the preparatory phase of periodization (P1 and P2: general training phase consisting of two sessions per day over the term during which the school held classes and during a summer vacation, respectively; and P3: intensive training phase consisting of four sessions per day during a summer vacation) using the factorial method and dietary records, respectively. The TrEE for P3 (1644±273 kcal) was significantly higher than that for P1 (891±230 kcal). However, the total energy intake (EI) for P3 (3274±889 kcal) was significantly lower than that for P1 (3978±938 kcal). The daytime (after waking in the morning and before the evening training session) EI (242±159 kcal) and protein intake (19±12 g) from the ‘high-protein foods group’ during P3 was significantly reduced compared with that during P1 (465±252 kcal, 37±15 g), whereas, EI and carbohydrate intake from the ‘supplements group’ of P3 was significantly increased compared with P1. The increased TrEE during P3 was not compensated by EI; instead, there was a decreased nutrient intake from the high-protein foods group and increased intake from the supplements group. The time of day of multiple or intensive training sessions, i.e. different TrEE, might affect the food choices made by male rugby players.

Effects of a physical activity support program based on bench-stepping exercise on physical fitness, mental health and health-related quality of life in Japanese returnees from China / 体力科学

This study aimed to examine the effects of an 8-week physical activity program, which mainly comprised home-based bench-stepping exercise training at the intensity of lactate threshold (LT), on mental health (MH), health-related quality of life (HRQOL), and physical fitness in Japanese returnees from China. Thirty Japanese returnees (63 ± 9 y) participated in the exercise program. Another six subjects were enrolled as the control group. The subjects performed 212 ± 57 min of training, and their daily step counts were increased. Aerobic capacity (LT: 4.5 ± 0.8 vs. 5.5 ± 1.1 METs), lower limb strength (30-s chair stand test [CS-30]: 19.1 ± 5.5 vs. 21.3 ± 5.1 times), and sit-and-reach flexibility (sitting-posture body anteflexion: 36.1 ± 9.4 vs. 39.0 ± 8.4 cm) were significantly increased after the intervention compared with before the intervention. Furthermore, MH, as assessed by the total score of the GHQ-28 (3.4 ± 4.4 vs. 0.3 ± 0.8 points), and the mental component score (MCS) of HRQOL, as evaluated by the SF-36v2 (55.1 ± 11.4 vs. 58.5 ± 10.0), were significantly changed in a positive manner. However, a two-way repeated measures ANOVA (group × period) showed significant interactions for LT and MCS (p<0.05), and a tendency for interactions of CS-30 (p=0.063) and the total score of the GHQ-28 (p=0.098). These results indicate that this bench-stepping exercise program could become a useful health support program for improving physical fitness, as well as MH and HRQOL, in Japanese returnees.

QUANTIFYING TIME SPENT IN MODERATE TO VIGOROUS INTENSITY PHYSICAL ACTIVITY VIA STEPPING RATE / 体力科学

The purpose of the present investigation was to examine the usefulness of the stepping rate for assessing the time spent in moderate to vigorous intensity physical activity (MVPA). In the present investigation, 11 young men wore two pedometers (LIFECORDER EX ; KZ, Walking Style ; WS) during controlled walking and jogging, as well as during free-living conditions for 3 days. In addition to the number of steps, the KZ determined the time spent in physical activity based on the intensity of the physical activity (light intensity physical activity (LPA); below 3 METs, and MVPA ; above 3 METs), and the stepping rate (≧60, ≧80, or ≧100 steps·min^-1). In contrast, the WS was defined as the physical activity for a stepping rate of 60 steps·min^-1 or more, continuously for longer than 10 min as the time spent in physical activity. Regarding the results, under continuous walking/jogging, the KZ-assessed LPA and MVPA well reflected the intensity of the physical activity. On the other hand, the WS accumulated the time spent in physical activity for longer than 90% of the actual exercise duration, regardless of the walking speed. Furthermore, the stepping rate corresponding to 3 METs was 102 steps·min^-1. Under free-living conditions, however, the KZ-detected MVPA differed significantly in comparison to the time of the physical activity as determined by the other algorithms, except for the time spent in a stepping rate of 80 or higher steps·min^-1. In conclusion, these results indicate that 100 steps·min^-1 is a useful stepping rate for the assessment of MVPA. However, under free living conditions, the stepping rate should be determined at a higher frequency than a one minute interval length in order to improve the accuracy of the MVPA assessment.

RELATIONSHIP BETWEEN DOUBLE PRODUCT BREAK POINT AND ST SEGMENT DEPRESSION ON ECG IN PATIENTS WITH ISCHEMIC HEART DISEASE PATIENTS AND ELDERLY PERSONS / 体力科学

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.