Osaka University of Health and Sport Sciences

Central blood volume (CBV) reduction challenges circulatory and respiratory homeostasis, particularly during the initial compensatory phase (0-2min), when rapid physiological adaptations occur. In this study, we examined dynamic cardiorespiratory responses to CBV reduction using lower-body negative pressure (LBNP) in 11 healthy young males. Participants completed three standardized 2min LBNP trials at -45mmHg, with respiratory variables assessed via flow measurement and breath-by-breath gas analysis, while cardiovascular parameters and cerebral blood flow were monitored using ECG, blood pressure and transcranial Doppler ultrasonography. During LBNP exposure, thoracic admittance, an indicator of CBV reduction, decreased by 13.4% (p<0.001), indicating significant CBV reduction. Following rigorous statistical correction for multiple comparisons, time-course analysis revealed that mean blood pressure decreased temporarily during the initial phase (0-30 s), whereas heart rate increased progressively (16.4%, p<0.001). End-tidal showed a consistent reduction (5.9%, p<0.001), whereas minute ventilation and middle cerebral artery mean blood velocity showed no significant changes after statistical correction (-9.3% and -5.0%, respectively, p>0.05). Exploratory correlation analysis revealed a significant negative correlation between mean blood pressure and tidal volume during the initial phase only (r=-0.78, p=0.004). Cross-correlation analysis suggested temporal patterns between respiratory and cerebrovascular responses, with respiratory changes preceding cerebrovascular adjustments by 10-20s. These findings, along with individual variability, suggest rapid cardiorespiratory and cerebrovascular interactions during orthostatic stress, demonstrating dynamic cardiovascular and respiratory responses with distinct temporal patterns that provide insights into physiological mechanisms maintaining homeostasis during gravitational stress.

Female reproductive status influences body composition, including fat mass (FM), fat-free mass (FFM), and bone health. We aimed to examine differences in body composition, bone health, and bioelectrical impedance analysis (BIA) parameters, including phase angle (PhA), among women with healthy menstruation, dysmenorrhea, and postmenopause. Forty-five female participants were included and divided into control (healthy menstruation; n = 13), dysmenorrhea (n = 14), and postmenopausal (n = 18) groups. Body composition, bone mineral density (BMD), bone mineral content (BMC), and BIA parameters were measured using dual-energy X-ray absorptiometry and multifrequency BIA. The postmenopausal group had significantly lower BMD, BMC, and PhA. In the control group, PhA was positively correlated with body mass, body mass index, FM, FM index, FFM, and FFM index, whereas no correlations were observed in the other groups. Classic bioelectrical impedance vector analysis (BIVA) parameters were consistent with FFM and FFM index, while specific BIVA aligned with body fat. Graphical BIVA analysis showed signs of edema and decreased body cell mass in the postmenopausal group. These findings highlight important differences in body composition, bone health, and bioelectrical parameters across reproductive stages, with a focus on managing muscle loss and edema according to reproductive status.

The objective of this study was to elucidate the characteristics of visually perceived momentum of others’ motions. Twenty participants watched and compared two consecutive point-light running motions: one at a fixed velocity of 8.0 km/h and the other at one of seven velocities (5.6, 6.4, 7.2, 8.0, 8.8, 9.6, and 10.4 km/h). They then evaluated which had greater momentum, or if they were the same. The results indicated that as the velocity deviated from the standard velocity of 8.0 km/h, the correct rates increased; in particular, the correct rate at 5.6 km/h, which differed the most from the standard velocity, was the greatest (p < .001). Additionally, the mean response times at 5.6 and 6.4 km/h, which were relatively smaller than the standard velocity, were significantly lower (both p < .05). This study indicates that humans can accurately perceive the momentum of others’ motions, consistent with previous studies demonstrating an accurate perception of the physical and mechanical properties of human-like motion.

This short-term survey examined the effect of body part pain on subjective and objective handball performance in Japanese male national handball athletes. Fourteen athletes participated in this study. Assessments of pain in 10 body parts and subjective performance (concentration and satisfaction with body movement) were performed using a visual analog scale from 0 to 10 over four consecutive training days. Monitoring of heart rate and body acceleration during training was also performed to quantify the objective performance. Path analysis and linear mixed modeling were employed to assess the relationship between body pain scores and subjective/objective handball performance. Over the four days of the study period, the body part in which most athletes reported pain was the dominant shoulder (6 of 14 athletes), followed by the dominant knee, the dominant elbow, the dominant ankle joint, and the non-dominant ankle joint (3 of 14 athletes). The path analysis revealed that pain in the dominant elbow negatively correlated with concentration (standardized path coefficient = -0.644, p = 0.00), which was associated with satisfaction with body movement (standardized path coefficient = 0.704, p = 0.00). No significant effect of body pain on objective performance (heart rate and body acceleration) was found among the athletes in this study. The results suggested that the elite athletes were practicing with pain. Even if pain does not physically affect athletes' objective performance, pain in the upper extremities, associated with the primary handball movement of throwing, may reduce the quality of practice by lowering athletes' subjective performance.

Athletes frequently assert their ability to foresee outcome in an upcoming game, often attributing it to so-called sixth sense. This paper investigates whether this foresight is genuine prediction, or a postdictive reconstruction that emerges post game. We conducted a study with 113 athletes to unravel this cognitive phenomenon. Participants completed a pre-game questionnaire, including queries about their mental and physical states, and more. Key to our investigation was the question: How do you think you will perform today? Subsequently, after the games, we administered a similar set of questions, introducing another critical query focused on postdictive reconstruction: How did you think you would perform this morning? Remarkably, even with the same question asked within 24 hours to the same participants, 60.2% of athletes altered their memory of their initial predictions, revealing a clear instance of postdictive reconstruction. Furthermore, an intriguing pattern emerged: those who experienced defeat tended to revise predictions negatively, while victors leaned towards more positive revisions. This interaction turned out highly significant, challenging the conventional cognitive tendency to maintain consistency with one's own past. These findings suggest an automatic and implicit inclination among athletes to postdictively adapt their memories of performance predictions to align with actual outcomes. Our study provides compelling evidence that athletes' claims of intuitive prediction are primarily postdictive in nature. This cognitive process sheds light on the role of memory in self assessment and the dynamic nature of human cognition, offering insights into athletes' psychological experiences and the broader domain of postdiction.

Abstract Background Duchenne muscular dystrophy (DMD) is an incurable neuromuscular disease leading to progressive skeletal muscle weakness and fatigue. Cell transplantation in murine models have shown promise in supplementing the lack of the dystrophin protein in DMD muscles. However, the establishment of novel, long-term, relevant methods is needed to assess its efficiency on the DMD motor function. By applying newly developed methods, this study aimed to evaluate the functional and molecular effects of cell therapy-mediated dystrophin supplementation on DMD muscles. Methods Dystrophin was supplemented in the gastrocnemius of a 5-week-old immunodeficient DMD mouse model (Dmd-null/NSG) by intramuscular xenotransplantation of healthy human immortalized myoblasts (Hu5/KD3). A long-term time-course comparative study was conducted between wild-type, untreated DMD, and dystrophin supplemented-DMD mouse muscle functions and histology. A novel GO-ATeam2 transgenic DMD mouse model was also generated to assess in vivo real-time ATP levels in gastrocnemius muscles during repeated contractions. Results We found that 10.6% dystrophin supplementation in DMD muscles was sufficient to prevent low values of gastrocnemius maximal isometric contraction torque (MCT) at rest, while muscle fatigue tolerance, assessed by MCT decline after treadmill running, was fully ameliorated in 21-week-old transplanted mice. None of the dystrophin-supplemented fibers were positive for muscle damage markers after treadmill running, with 85.5% demonstrating the utilization of oxidative metabolism. Furthermore, ATP levels in response to repeated muscle contractions tended to improve, and mitochondrial activity was significantly enhanced in dystrophin supplemented-fibers. Conclusions Cell therapy-mediated dystrophin supplementation efficiently improved DMD muscle functions, as evaluated using newly developed evaluation methods. The enhanced muscle fatigue tolerance in 21-week-old mice was associated with the preferential regeneration of damage-resistant and oxidative fibers, highlighting increased mitochondrial activity, after cell transplantation. These findings significantly contribute to a more in-depth understanding of DMD pathogenesis.