The purpose of this study was to analyze head impact kinematics at different locations of Japanese university American football players using a 6DOF (degrees of freedom) device. The subjects of this study were 43 players who belonged to T University in the Kanto Collegiate American Football Association second division. We used a Vector Mouthguard (i1 Biometrics Inc.) equipped with a 6DOF to measure the head LA (linear acceleration), AA (angular acceleration) and AV (angular velocity), as well as the number of head impacts during collisions, and evaluated 4 impact locations (front, side, back, and top) in detail. The total number of head impacts was 2,070 during games and 10,007 during practice sessions for a total of 7 games and 41 practices during fall regular seasons over a 2-year period. The most common head impact location was the front (43.5%), followed by the side (41.9%), top (10.9%), and back (3.7%). When classifying the total number of head impacts at these locations according to player position, skill players showed the highest proportion of side impacts (p < 0.05), whereas linemen showed the highest proportion of frontal impacts (p < 0.05) compared to the other locations. These results support previous studies conducted for university American football players in the United States. That is, the frequency and location of head impacts is greatly influenced by player position. Regarding the magnitude of head impact locations, the LA and AA values for back of the head impacts were the highest both at games and practice sessions. In addition, the AA value for impacts to the top of the head was much higher than the AA value for impacts to the front and side (p < 0.05). Also, there were significant positive correlations between peak LA and peak AA at all head impact locations for games and practice sessions based on player position (p < 0.05). Skill players showed significant positive correlations between peak AA and peak AV at all head impact locations in games (p < 0.05). In comparison, linemen showed significant positive correlations between peak AA and peak AV for frontal and side impacts for games and frontal, side, and top of head impacts in practice sessions (p < 0.05). As a result, it was clear that Japanese university American football players could not stabilize the head during collisions. In conclusion, it was found that the frequency of head impact locations in Japanese university American football players was the same as that in the USA. In head impact kinematics during collisions, Japanese university American football players showed different characteristics from their American counterparts. In the future, we should take into account neck muscular strength and motion analysis to better understand the influence of head impacts on Japanese university American football players.
We measured and compared the diet-induced increase in resting oxygen uptake (DIIROU) after moderate-intensity exercise (MIE) with the DIIROU after high-intensity intermittent exercise (HIIE). Eight healthy adult males participated in six testing sessions, including the measurement of resting oxygen uptake with and without lunch after MIE, HIIE, and as a non-exercise control. The MIE was 30 min of exercise at an intensity of 70% VO2max, and the HIIE consisted of seven to eight 20 second bouts of exhaustive exercise at 170% VO2max with 10-sec rests between the bouts. The exercise time of the HIIE for the no-lunch (fasting) experiment (144.1 ± 10.0 sec) was not significantly different from that for the lunch experiment (142.8 ± 10.3 sec). Lunch (713 kcal) was served for the lunch experiment at 12:00, which corresponds to ~1.5 hr after each exercise. Compared to the non-exercise control results, the accumulated oxygen uptake (AOU) of the MIE and HIIE were significantly higher from the end of the exercise until 11:30 (p < 0.001). However, no difference in AOU was noted from 11:30 to 12:00 between the control and MIE or HIIE results, suggesting that excess post-exercise oxygen consumption wore off before 12:00. The values of DIIROU (quantified as the difference in AOU between the lunch and fasting experiment from 12:00 to 16:00) after HIIE, MIE, and the non-exercise control were 132.7 ± 37.2, 102.8 ± 48.0, and 77.8 ± 40.7 ml/kg, respectively. The ΔDIIROU for the MIE (25.0 ± 17.8 ml/kg) calculated as the difference in DIIROU from the non-exercise control was significantly less than that of the HIIE (55.0 ± 25.4 ml/kg) (p < 0.01). These results may indicate that MIE potentiates a diet-induced increase in resting oxygen uptake, even though this effect was less than that of HIIE and was quantitatively small.
There was a nutritional issue in the training camp of Central Java BPPLOP (Balai Pemusatan Pendidikan Latihan Olahraga Pelajar/Student Sport Education and Training Center). The year 2017 data showed that 8% of athletes experienced nutritional deficiency and 10% of athletes experienced nutritional excess. This research aimed to evaluate the effectiveness of a personalized nutrition program toward percentage of energy consumption level (%ECL), body mass index (BMI), and body fat percentage (%BF). This research utilized one-group pretest-posttest design. The subjects were 59 martial arts athletes in Central Java BPPLOP. The personalized nutrition program intervention lasted a month and was encouraged by a smartphone application called Nutriatlet. The statistical test was a paired sample t test. The research concluded that mean %ECL improved significantly after intervention, from 63.37 ± 8.57 to 82.91 ± 6.31 (p < 0.001). The BF percentage also improved from 14.36 ± 6.19 to 13.40 ± 5.88 (p < 0.001). Mean BMI was not significantly different after intervention, from 21.95 ± 2.51 to 22.02 ± 2.25 (p = 0.524). We concluded that Nutriatlet usage to evaluate a personalized nutrition program could improve the energy consumption level and body fat percentage while maintaining body mass index.
The purposes of the present study were (a) to determine whether a self-reported dominant leg was consistent with a dominant leg of force generation by using the isometric mid-thigh pull (IMTP) tests and (b) identify the features of bilateral IMTP (IMTPBi) and unilateral IMTP (IMTPUni) in terms of detecting strength imbalance of athletes. Fifteen male collegiate athletes performed IMTPUni and IMTPBi. The ground reaction force and surface electromyography were sampled with 1000Hz to assess force generation and neuromuscular activities in the gluteus maximus (Gmax), gluteus medius (Gmed), semitendinosus (ST), biceps femoris (BF), rectus femoris (RF) and vastus lateralis (VL) during IMTP. Legs were separated into dominant and non-dominant leg categories in accordance with two types of definitions including self-reported dominance of kicking leg and dominance of force generation in IMTP. In force generation and neuromuscular activity of IMTPBi and IMTPUni, there was no significant difference between self-reported dominant and non-dominant leg. However, results for a self-reported dominant leg were not consistent with results for dominant leg determined by force generation. In addition, the dominant leg of force generation exerted significantly larger PF than non-dominant leg, and the magnitude of asymmetry in IMTPBi was significantly larger than that of IMTPUni. Moreover, in IMTPBi, the neuromuscular activity of the VL of the dominant leg of force generation was significantly larger than that of the non-dominant leg. Therefore, it was suggested the necessity to distinguish the two types of IMTP tests because of the possibility that the strength imbalances detected by IMTPBi and IMTPUni would have different connotations.
The amygdala induces emotion and controls the cardiovascular system. We previously found that lesions in the central nucleus of amygdala (CeA), which is associated with negative emotion, chronically increase the arterial pressure (AP); however, the mechanism involved in this process remains unclear. In this study we compared the heart rate (HR), high frequency (HF) component of HR variability as an index of cardiac vagal outflow, and spontaneous baroreceptor reflex gain (sBRG) before and after the occurrence of bilateral lesions in CeA for further understanding of cardiovascular regulation by CeA. The results showed that CeA lesions induced a chronic decrease in HR and increase in sBRG, suggesting that CeA regulates the autonomic nervous system. Taken together with our previous results, CeA was shown to control AP and HR as well as baroreflex gain; however, the mechanisms controlling basal AP through CeA are likely to be independent of mechanisms for baroreflex gain control. These contradictory findings may partially explain the known diverse hemodynamic patterns of the amygdala in response to a variety of stress conditions.
In healthy individuals, swimming seems to increase resting systolic blood pressure (SBP). However, the mechanisms responsible for SBP elevation associated with swimming have not been elucidated. Therefore, this study investigated cardiovascular morphology and function in healthy young male swimmers. Brachial SBP was higher in swimmers than non-swimmers. Left ventricular (LV) wall thickness and forearm blood flow (BF) and vascular conductance (VC) were also higher in swimmers relative to non-swimmers. In a stepwise regression analysis that included physical characteristics and cardiovascular morphology, LV wall thickness was an independent predictor of brachial SBP. When parameters related to cardiovascular function were added to the analysis, forearm BF and VC were identified as independent predictors of brachial SBP. LV wall thickness was correlated with forearm BF. Increases in BF to the forearm muscles may explain the brachial SBP elevation in swimmers. LV wall hypertrophy may be associated with brachial SBP elevation via increases in forearm BF.