The relationships between physical activity and childhood body size, low physical fitness epidemic are still unclear. The purpose of this study was to examine the relationship between energy expenditure estimated by doubly labeled water (DLW) method and body fatness, physical fitness in children, and the relationship between physical activity levels and percent time spent in activities. 30 healthy Japanese children (20 boys and 10 girls) participated in this study. The total energy expenditure (TEE) and % body fat were measured by the DLW method over a 6-day period. The physical activity-related energy expenditure (PAEE) was calculated as (TEE × 0.90) – basal metabolic rate (BMR). The physical activity level (PAL) was also calculated as TEE/BMR. The physical fitness tests (8 items) were applied to evaluate fitness, and scores of each test were calculated as overall physical fitness score. The TEE was 2009.8 ± 272.6 kcal/day, the PAEE was 558.4 ± 206.1 kcal/day and the PAL was 1.61 ± 0.18. TEE per weight and PAEE per weight (PAEE/wt) was significantly negatively correlated with % body fat (r = - 0.626; r = - 0.400, respectively). These results suggest that increasing energy expenditure is important for achieving adequate body size. The PAEE/wt was most strongly correlated with physical fitness score (r = 0.680). The PAL was associated with percent time spent of inactivity ( r = -0.506), light-moderate activity ( r = 0.450) and vigorous activity ( r = 0.545). It was suggested that physically active lifestyle would be necessary for childhood health.
We investigated muscle activities of the scapular muscles during low row procedure (LR) usually used 12 weeks after a rotator cuff repair, and evaluated its effective application period comparing with scapular retraction procedure (SR) used for early postoperative period. Twelve healthy adults (mean age, 26.8 years) were enrolled in the current study. %MVICs (maximal voluntary isometric muscle contractions) of middle trapezius, lower trapezius, serratus anterior, posterior deltoid, and infraspinatus were calculated from the surface electromyography during both LR and SR. The %MVIC of either the middle trapezius or lower trapezius was not significantly different between during the LR and the SR. The %MVIC of the serratus anterior, posterior deltoid and infraspinatus during the LR was significantly higher than those during the SR (p=0.018, p<0.001, p<0.001, respectively). Additionally, the %MVIC of the posterior deltoid and infraspinatus in the SR was less than 20%. In training phase after rotator cuff repair, LR was considered to be effective procedure for most of the scapular muscles 12 weeks after a surgical repair of the rotator cuff. However, LR earlier than 12 weeks after the surgery is considered to yield a risk of re-tear of the rotator cuff, and SR may be a preferred training procedure in this early phase.
The purpose of this study was to determine the relationship in prepubertal children between lower limb muscle thickness, a quantitative index of lower limb muscle, and sprint motion, in order to clarify the effects of muscle mass development on sprint motion as well as differences in these effects due to sex and muscle location. Participants comprised 41 children in 8year-old (21 boys, 20 girls) in good health attending an elementary school in the city of Kitakyushu. Muscle thickness of the anterior thigh (MTa), posterior thigh (MTp), and calf (MTC) were measured using B-mode ultrasonography. Sprint abilities (sprint speed, stride length, and step frequency), kinematic indices relating to sprint motion and ground reaction force were also measured. Pearson product-moment correlation coefficients were calculated to determine relationships between measured variables. Effects of height and weight were eliminated, and stepwise multiple linear regression analysis was performed, using stride length and step frequency as dependent variables, and kinematic indices and ground reaction force as independent variables. In boys, posterior thigh muscle thickness and calf muscle thickness showed significant simple correlations with flying time/support time (FT/ST), which was selected as an explanatory variable for step frequency. However, no significant relationship was found between step frequency and sprint speed. The conclusion of these findings is that developing lower limb muscle mass affects sprint motion in 8-year-old boys, but does not directly lead to improved sprint speed. In girls, a significant relationship was found between posterior thigh muscle thickness and maximal leg swing velocity during the support phase (ωL), which was selected as an explanatory variable for step frequency, and a significant relationship was found between step frequency and sprint speed. Unlike boys, developing lower limb muscle mass in 8-year-old girls influences step frequency and is closely connected to sprint speed.
Several studies have shown that low cardiorespiratory fitness (CRF) or heavy alcohol consumption is risks of total or certain types of cancer death. However, the combined influence of CRF and drinking habits on total cancer mortality is not clear. The purpose of this study was to investigate the joint effect of CRF and drinking habits on total cancer mortality among Japanese men. We evaluated the CRF and drinking habits on risk of total cancer mortality in 8,760 Japanese men (age: 19-59 yr) who were given a submaximal exercise test, a medical examination test, and questionnaires on their health habits. CRF was measured using a cycle ergometer test, and the men were classified into two categories by CRF levels based on the reference value of CRF (R-CRF) in “Physical Activity Reference for Health Promotion 2013” (Under R-CRF and Over R-CRF). Also, the men were assigned to Non Drinking, Moderate Drinking, and Heavy Drinking categories. There were 178 cancer deaths during the 20-yr follow-up period. Relative risk and 95% confidence intervals for total cancer mortality were obtained using the Cox proportional hazards model while adjusting for age, body mass index, systolic blood pressure, and smoking habits. Using the Under R-CRF & Heavy Drinking group as reference, the relative risk and 95% confidence intervals were 0.37 (0.16–0.85) for the Over R-CRF & Non Drinking group. This result suggests that Japanese male with a high CRF and a low drinking habit have a lower risk of total cancer mortality.
This study aimed to examine a new walking method to fulfill the Physical Activity Reference for Health Promotion in Japan in a shorter time, which can be performed as a non-exercise activity (NEA) such as walking during commuting. Eleven healthy subjects performed normal walking (NW) and knee-up walking (KU) for eight minutes without load (0%) and with loads of 5, 10, and 20% of body mass in a backpack carried on the back (NW-0, 5, 10, and 20; KU-0, 5, 10, and 20) on a treadmill at a speed of 5 km/h at 0% tilt. Oxygen uptake, blood lactate levels, and ratings of perceived exertion (RPE) were measured in the last two minutes of each walking stage. Metabolic equivalents (METs) were also calculated from the resultant oxygen uptake. METs in NW-20 and all weight conditions of KUs were significantly greater (P < 0.01) than those in NW-0 (3.8 ± 0.1 METs). RPE in both KU-10 and KU-20 was above 15 (i.e., indicating Hard). Blood lactate levels in the KU-20 (4.5 ± 0.7 mmol/L) were above the Onset of Blood Lactate Accumulation. On the other hand, NW-20, KU-0, and KU-5 were physical activity level of moderate- to vigorous- intensity that could be performed as a NEA. These data suggest that our new walking methods such as NW-20, KU-0, and KU-5 can satisfy the Physical Activity Reference in a shorter time rather than normal walking, and could be continuously performed in daily life.
The purpose of this study was to examine the relationships between patterns of daily physical activities measured by accelerometer and physical activity level (PAL) in children. Firstly, activity intensities during incremental exercise were measured using a tri-axial accelerometer (HJA-350IT) in twenty one children aged 10.6 ± 0.9 years. As a result of receiver-operating characteristic curve analysis, the cut-off value for discrimination between walking and running activity was set at 7.2 METs of HJA-350IT. Secondly, total energy expenditure (TEE) in daily life was measured by doubly labeled water method, and durations of lifestyle, walking, and running activities were measured by the accelerometer in 6th grade elementary school children (11 boys and 10 girls). TEE and physical activity level (PAL) were 2,021 ± 343 kcal/day and 1.56 ± 0.17, respectively. The average durations of lifestyle, walking and running activities were 188 ± 30 min/day (50.6 ± 6.0 %), 171±28 min/day (45.9 ± 5.0 %) and 13.3 ± 7.6 min/day (3.5 ± 1.8 %), respectively. The proportion of the duration of running activity was positively correlated with PAL (r = 0.615, p < 0.01), and the proportion of the duration of lifestyle activity was negatively correlated with PAL (r = -0.439, p < 0.05). There was no relationship between the proportion of the duration of walking activity and PAL (r = 0.300, n.s.). These results suggest that running activity is important to increase PAL more than ever in primary school children.
The purpose of this prospective study was to examine the injury characteristics in collegiate women’s lacrosse players. Injury data were collected from the Division I collegiate women’s lacrosse team for a 2-year. The total athlete-hours and athlete-exposures over the 2-year period were 27,621 and 13,437, respectively. The total number of injury was 309 injuries, and the total incidence rate was 11.19 injuries (95% confidence interval, 9.94 — 12.43) per 1000 athlete-hours and 23.00 injuries (20.43 — 25.56) per 1000 athlete-exposures, respectively. The most frequent location of injury was the ankle, followed by the knee and the thigh (20.1%, 14.6%, and 10.7% of all injuries). The proportion of lower extremity injuries accounted for 73.5% of all injuries. The most common types of injury was sprains and muscle cramps/spasms (24.9% and 24.6%, respectively). Overuse, contact (e.g., other players, the cross, and the ball), and non-contact injury was the 3 most common cause of injury (39.1%, 24.9%, and 17.2%, respectively). The primary injury characteristics of collegiate women’s lacrosse players were non-contact ankle sprain. Injury recurrence accounted for 26.1% of all injuries, and the most common period required for the player to return to practice and/or games was between 3 and 7 days. Midfield position player suffered the most number of injuries compared to other position player. An understanding of the injury characteristics of women’s lacrosse players may facilitate the development of the comprehensive strategy for injury prevention which is recommended by the sports medicine community.
The purpose of this study was to clarify the body composition and blood profile in college American football players, and whether the differences can be referred to their playing positions; Lines vs Backs. Body compositions, blood profile and nutrients intake were investigated. The Linemen showed a significant higher %BF than Backs, and most of the Linemen were assessed as obese according to their %BF and BMI. The risk of dyslipidemia in Linemen was higher than that in the Backs. There were no obvious difference between Linemen and Backs in their intake amount of energy and all nutrients per person. However, when compared in per body-weight, the intake amount of energy and 3 major nutrients were significantly low in Linemen than Backs. Furthermore, the data indicate that dietary awareness and diet behavior are relatively poor in the Linemen. Since body weight is the most crucial factor of Linemen for their playing performances, it can be speculated that their necessity to gain body weight may have led them to be obesity. Since weight-gain is not desirable in the aspect of metabolic disorders prevention, our result indicated that Linemen, rather than the Backs, are the potential target who need an appropriate nutritional support by dietician to control their nutritional intake and body weight, not only for achieving sport performance but also for preventing metabolic disorders. Therefore, it was suggested that periodical survey of blood profile and body composition, together with appropriate nutritional support by dieticians, may be helpful for Linemen, in future.