先天性心脏病的分子机制研究进展

先天性心脏病是出生缺陷最常见的畸形,其病因仍不清楚。分子遗传学、发育生物学的进展,发现了许多和心脏发育有关的基因。先天性心脏病(CHD)是发育缺陷导致的畸形,其分子机制很复杂。文章综述总结正常的心脏发育过程和概括先天性心脏病相关基因通路,分析先天性心脏病的可能机制,并提出相应研究策略。     

Reliability and Validity of a New Physical Activity Self-Report Measure for Younger Children

The purpose of this study was to assess the test–retest reliability and validity of a new Youth Physical Activity Self-Report measure. Heart rate and direct observation were employed as criterion measures with a sample of 79 children (aged 7–9 years). Spearman's rho (ρ) correlation between self reported activity intensity and heart rate was .87 for weekday and .795 for weekend; the correlation between self-reported activity duration and duration as measured by heart rate were .837 and .684 for weekday and weekend, respectively. These correlations fell when recalled inactivity was excluded from analysis. A correlation of ρ = .557 was found between self-reported activity intensity and direct observation. Results establish support for the self-report measure as an effective tool for measuring the previous day physical activity of younger children.     

The effect on heart rate variability of acclimatization to a humid,hot environment after a transition across five time zones in elite junior rowers

Abstract

The aim of this study was to examine the simultaneous effect on heart rate variability (HRV) of acclimatization to a hot, humid environment and a transition of five time zones in elite junior rowers. Thirteen rowers (12 males and 1 female) participated in the study. Each rower was monitored during training camps in temperate and in humid, hot conditions before and during the Junior Rowing World Championship. All participants recorded the lengths of high-intensity training sessions, and R-R (the time between the R peaks of consecutive QRS complexes) intervals were measured every morning after awakening. Compared with baseline values taken during training before the transition to the new time zone and climate, HRV indices during first 3 days of acclimatization remained unchanged. On the fourth and fifth days of acclimatization, significant decreases in measures of heart rate variability in the standing position were observed. Beginning from the sixth day of acclimatization and for all subsequent days, the HRV indices, while standing, returned to baseline values and were not significantly different from baseline. Despite this, there were no significant changes in HRV measures in a supine position until the eighth day of acclimatization. R-R intervals decreased and mean heart rate increased significantly (P<0.001) during days 8–10 of acclimatization. In conclusion, major physiological adaptation of HRV indices in the standing position during acclimatization to a humid, hot environment, with a transition across five time zones, occurs within the first 5 days in elite athletes before returning to baseline. Indices of heart rate variability in the supine position correlate with the length of high-intensity training sessions on the previous day.     

1500m耐力训练中实施心率和血乳酸监测的研究

为了探求1500m运动员耐力训练的最优效果,采用实验法、数据统计法等研究方法,对哈尔滨市省属3所高校10名男子1500m运动员运用5级递增负荷法进行无氧阈的测试,并对心率和血乳酸等生理指标进行监控、分析和评价。实验结果显示:(1)无氧阈强度时血乳酸与心率的变化曲线高度相关,可以用心率来代替血乳酸指标指导训练,是1500m训练中控制运动强度的简便易行的有效方法;(2)高校1500m运动员耐力训练可以参照171±9.2这个范围作为男子无氧阈强度的临界心率,以3.9mmo1/L作为乳酸无氧阈的临界值。(3)在实际训练中可以采用低强度训练负荷、长时间中强度耐力训练和间歇性大强度训练等方法。     

Concentric left ventricular morphology in aerobically trained kayak canoeists

The aim of the present study was to test the hypothesis that upper body aerobically trained athletes (kayak canoeists) would have greater left ventricular wall thickness, but similar left ventricular diastolic chamber dimensions, compared with recreationally active and sedentary men. Ultrasound echocardiography was used to determine cardiac structure and function in highly trained kayak canoeists (n?=?10), moderately active (n?=?10) and sedentary men (n?=?10). The septal and posterior left ventricular walls were ～0.2?cm thicker in kayak canoeists (P?<?0.05), and left ventricular mass was 51% and 32% greater (P?<?0.05) in canoeists than in the sedentary and moderately trained participants, respectively. There were no differences in left ventricular chamber dimension, suggesting that the kayak canoeists had a concentric pattern of left ventricular adaptation to aerobic upper body training. Scaling the data to body composition indices had no effect on the outcome of the statistical analysis. There were no differences in resting Doppler left ventricular diastolic or systolic function among the groups. Ejection fraction was lower in the kayak canoeists, but the magnitude of the difference was within the normal variability for this measurement. Thus aerobically upper body trained athletes demonstrated a concentric pattern of cardiac enlargement, but resting left ventricle function was not different between athletes, moderately active and sedentary individuals.     

The measurement of competitive anxiety during balance beam performance in gymnasts

Abstract

The purpose of the present study was to investigate competitive anxiety during balance beam performance in gymnasts. Competitive anxiety was assessed continuously by heart rate monitoring and by retrospective self-report of nervousness in eight female national level gymnasts during their balance beam routine during one competition and two training sessions. A significant negative correlation was found between the score of the retrospective self-report of nervousness and performance during the routine. There were no significant differences in performance score by the judges between the three test sessions. There were also no differences in the retrospective self-report of nervousness. However, heart rate was significantly higher during the competition session than during the training sessions. The potential value of the retrospective report of nervousness for the study of critical events during gymnastic performance is illustrated. The results are discussed in the light of catastrophe theory.     

Sampling period determination for heart rate logging under an exercise regimen

Abstract

Using a mathematical procedure, we determine appropriate sampling rates for logging heart rate, at a variety of exercise intensities. The mathematical procedure involves correlating exercise and heart rate data to determine a dynamical mathematical model, from which the frequency response of the relationship between exercise intensity and heart rate can be determined. The sampling rate is then straightforwardly deduced by making appropriate measurements on the frequency response curve. We show how careful consideration needs to be given to the choice of dynamical model structure and the work regimen, so that consistent and convincing conclusions can be drawn. We demonstrate that the dynamics of the work-rate/heart-rate system are dependent on the nominal work/heart rate, but a 5-s sampling period, as used in many commercial heart rate monitors, appears to be adequate, especially when some averaging is performed before logging.     

Activity profile and physical demands of football referees and assistant referees in international games

Abstract

Time-motion analyses and physiological measurements were performed to investigate the physiological demands of football referees (n = 15) and assistant referees (n = 15) in international games and to examine whether high-intensity running (HIR) correlates to the referees' ability to keep up with play. Total distance covered (10.27 ± 0.90 vs. 6.76 ± 0.83 km) and HIR (1.92 ± 0.58 vs. 0.97 ± 0.22 km) was higher (P < 0.05) for referees than assistant referees, while sprinting distance was not different. Referees covered 0.89 ± 0.37 km by backwards running and assistant referees covered 1.54 ± 0.66 km by sideways running. Mean heart rate was higher (P < 0.05) for referees than assistant referees (150 ± 3 vs. 123 ± 3 b.p.m.), whereas blood lactate was not different. Backwards/sideways running decreased (P < 0.05) from the first to the last 15-min period for referees (49%) and assistant referees (42%), whereas HIR was unaltered. HIR was inversely correlated with the five highest distances from infringements in both halves (r = ?0.60 and ?0.58, P < 0.05). In conclusion, international match officials carry out an important amount of HIR throughout games, while low-intensity and unorthodox running activities are reduced during games. Referees performing the most high-intensity work are better to keep up with play. The match activities differ significantly between referees and assistant referees, which should be considered in training and testing procedures.     

Time–motion,heart rate,perceptual and motor behaviour demands in small-sides soccer games: Effects of pitch size

Abstract

The aim of this study was to examine physical, physiological, and motor responses and perceived exertion during different soccer drills. In small-sided games, the individual playing area (～275 m², ～175 m², and ～75 m²) was varied while the number of players per team was kept constant: 5 vs. 5 plus goalkeepers. Participants were ten male youth soccer players. Each session comprised three small-sided game formats, which lasted 8 min each with a 5-min passive rest period between them. A range of variables was recorded and analysed for the three drills performed over three training sessions: (a) physiological, measured using Polar Team devices; (b) physical, using GPS SPI elite devices; (c) perceived exertion, rated using the CR-10 scale; and (d) motor response, evaluated using an observational tool that was specially designed for this study. Significant differences were observed for most of the variables studied. When the individual playing area was larger, the effective playing time, the physical (total distance covered; distances covered in low-intensity running, medium-intensity running, and high-intensity running; distance covered per minute; maximum speed; work-to-rest ratio; sprint frequency) and physiological workload (percent maximum heart rate; percent mean heart rate; time spent above 90% maximum heart rate), and the rating of perceived exertion were all higher, while certain motor behaviours were observed less frequently (interception, control and dribble, control and shoot, clearance, and putting the ball in play). The results show that the size of the pitch should be taken into account when planning training drills, as it influences the intensity of the task and the motor response of players.     

Yo-Yo IR2 testing of elite and sub-elite soccer players: Performance,heart rate response and correlations to other interval tests

Abstract

We examined performance, heart rate response and construct validity of the Yo-Yo IR2 test by testing 111 elite and 92 sub-elite soccer players from Norway and Denmark. VO₂max, Yo-Yo IR1 and repeated sprint tests (RSA) (n = 51) and match-analyses (n = 39) were also performed. Yo-Yo IR2 and Yo-Yo IR1 performance was 41 and 25% better (P < 0.01) for elite than sub-elite players, respectively, and heart rate after 2 and 4 min of the Yo-Yo IR2 test was 20 and 15 bpm (9 and 6% HRmax), respectively, lower (P < 0.01) for elite players. RSA performance and VO₂max was not different between competitive levels (P > 0.05). For top-teams, Yo-Yo IR2 performance (28%) and sprinting distance (25%) during match were greater (P < 0.05) than for bottom-teams. For elite and sub-elite players, Yo-Yo IR2 performance was correlated (P < 0.05) with Yo-Yo IR1 performance (r = 0.74 and 0.76) and mean RSA time (r = ?0.74 and ?0.34). We conclude that the Yo-Yo IR2 test has a high discriminant and concurrent validity, as it discriminates between players of different within- and between-league competitive levels and is correlated to other frequently used intermittent elite soccer tests.