Does endurance training improve red blood cell aging and hemorheology in moderate-trained healthy individuals?

ObjectiveTo examine the impact of a 6-week endurance training on red blood cell (RBC) aging and deformability of healthy participants to detect possible improved hemorheological and performance-related adaptations.MethodsA total of 31 participants (17 females and 14 males) performed a 6-week moderate training protocol (three 1-h running sessions per week at 70% of maximal heart rate). Blood was sampled before and after the training. RBCs from each participant were fractioned according to density and age into 4 RBC subfractions. Subfractions were examined for changes of RBC properties, including aging distribution, RBC deformability, RBC microparticles, and phosphatidylserine concentrations. RBC and plasma nitrite levels were measured as indicators of nitric oxide metabolism.ResultsAerobic performance, peak oxygen consumption, ventilatory thresholds, velocity at the aerobic–anaerobic threshold, and lactate at exhaustion improved after training. The relative amount of both young RBCs and old RBCs increased, and the amount of the main RBC fraction decreased. Phosphatidylserine externalization and RBC-derived microparticles decreased. Overall deformability expressed as shear stress required to achieve half-maximum deformation to theoretical maximal elongation index at infinite shear stress improved in unfractioned RBCs (p < 0.001). Nitrite decreased in total (p = 0.001), young (p < 0.001), main (p < 0.001), and old (p = 0.020) aged RBCs and in plasma (p = 0.002), but not in very old RBCs.ConclusionThese results indicate that non-endurance-trained healthy participants benefit from a regular moderate running training program because performance-related parameters improve and a younger RBC population with improved RBC properties is induced, which might support oxygen supply in the microcirculation.     

Fast bowling arm actions and the illegal delivery law in men's high performance cricket matches

This study investigated the bowling arm kinematics of 21 elite fast bowlers (mean +/- SD; age = 27.8 +/- 3.9 years) while performing in test, tour and one day international matches. Thirty-one of the 34 deliveries analysed exhibited straightening at the elbow joint (straightening min = 3 degrees, max = 22 degrees, mean +/- SD = 9 +/- 5 degrees), which by strict definition in the 2000 laws of cricket made them illegal. Five deliveries from three bowlers exhibited hyperextension of the bowling elbow (19 +/- 5 degrees). When assessed against an arbitrary threshold of 15 degrees for elbow straightening, ball speeds for deliveries above this threshold (39.5 +/- 2.0 m/s) were significantly faster (effect size = 1.4; p = 0.006) than deliveries below it (37.1 +/- 1.4 m/s). When grouped by delivery length, the bouncers and short deliveries recorded more elbow straightening (12 +/- 6.6 degrees) than the good length deliveries (9 +/- 4.4 degrees) and the full deliveries (8 +/- 5.7 degrees), although these were not statistically significant differences. The results of this study support the implementation of a tolerance threshold for assessing the legality of fast bowling actions. Further research is recommended into in-match kinematic modelling, laboratory based assessments of illegal bowling actions, perceptual aspects of bowling actions and remedial methods to reduce elbow straightening in bowling actions.     

Post-exercise ingestion of a unique, high molecular weight glucose polymer solution improves performance during a subsequent bout of cycling exercise

The aim of the present study was to determine the effect of post-exercise ingestion of a unique, high molecular weight glucose polymer solution, known to augment gastric emptying and post-exercise muscle glycogen re-synthesis, on performance during a subsequent bout of intense exercise. On three randomized visits, eight healthy men cycled to exhaustion at 73.0% (s = 1.3) maximal oxygen uptake (90 min, s = 15). Immediately after this, participants consumed a one-litre solution containing sugar-free flavoured water (control), 100 g of a low molecular weight glucose polymer or 100 g of a very high molecular weight glucose polymer, and rested on a bed for 2 h. After recovery, a 15-min time-trial was performed on a cycle ergometer, during which work output was determined. Post-exercise ingestion of the very high molecular weight glucose polymer solution resulted in faster and greater increases in blood glucose (P < 0.001) and serum insulin (P < 0.01) concentrations than the low molecular weight glucose polymer solution, and greater work output during the 15-min time-trial (164.1 kJ, s = 21.1) than both the sugar-free flavoured water (137.5 kJ, s = 24.2; P < 0.05) and the low molecular weight glucose polymer (149.4 kJ, s = 21.8; P < 0.05) solutions. These findings could be of practical importance for athletes wishing to optimize performance by facilitating rapid re-synthesis of the muscle glycogen store during recovery following prolonged sub-maximal exercise.     

Practical precooling: effect on cycling time trial performance in warm conditions

The purpose of this study was to compare the effects of two practical precooling techniques (skin cooling vs. skin + core cooling) on cycling time trial performance in warm conditions. Six trained cyclists completed one maximal graded exercise test (VO2(peak) 71.4 +/- 3.2 ml x kg(-1) x min(-1)) and four approximately 40 min laboratory cycling time trials in a heat chamber (34.3 degrees C +/- 1.1 degrees C; 41.2% +/- 3.0% rh) using a fixed-power/variable-power format. Cyclists prepared for the time trial using three techniques administered in a randomised order prior to the warm-up: (1) no cooling (control), (2) cooling jacket for 40 min (jacket) or (3) 30-min water immersion followed by a cooling jacket application for 40 min (combined). Rectal temperature prior to the time trial was 37.8 degrees C +/- 0.1 degrees C in control, similar in jacket (37.8 degrees C +/- 0.3 degrees C) and lower in combined (37.1 degrees C +/- 0.2 degrees C, P < 0.01). Compared with the control trial, time trial performance was not different for jacket precooling (-16 +/- 36 s, -0.7%; P = 0.35) but was faster for combined precooling (-42 +/- 25 s, - .8%; P = 0.009). In conclusion, a practical combined precooling strategy that involves immersion in cool water followed by the use of a cooling jacket can produce decrease in rectal temperature that persist throughout a warm-up and improve laboratory cycling time trial performance in warm conditions.     

Effects of crowd size on referee decisions: analysis of the FA Cup

Data were collected on the number of first yellow cards awarded during 857 games, over six seasons (1996 - 2002), played in the Football Association (FA) Cup. Overall, a significantly higher number of yellow cards were awarded against the away team, while a non-linear relationship between crowd size and yellow cards was observed. In general, the probability of a yellow card being awarded against the home team decreased as crowd size increased, but was attenuated for the largest crowd sizes. Crowd size may be related to the probability of the home team receiving a yellow card in two potential ways. Crowd noise may be a decision-making heuristic whereby the likelihood that an incident is a foul is increased when accompanied by crowd noise. Alternatively, referees may seek to appease the crowd and are more likely to do so as crowd size increases. The present findings have implications for the training of match officials and for coaches and players as they prepare to play away from home.     

中西方不同视角下武术国际化发展的现状和未来

武术的国际化一直是热点问题,研究将对武术的国际化发展现状进行一次全面地调查,并分析研究造成这些状况的深层次原因,探索适合中国武术国际化发展之路.结果显示,武术发展在世界各洲发展极不平衡,各国习武人数总体偏少,多数国家只有一个武术协会,但有1/3的国家有多个武术协会并存的现象.武术师资缺乏、武术教学水平低下是目前制约各国武术发展的最主要的因素,并提出重视学校武术的发展,利用孔子学院扩大武术练习人口,建立科学、合理可行的教练员等级和培训制度等建议.     

A second look at Egghe’s universal IR surface and a simple derivation of a complete set of universal IR evaluation points

Egghe’s three papers regarding the universal IR surface (2004, 2007, 2008) clearly represent an original and significant contribution to the IR evaluation literature. However, Egghe’s attempt to find a complete set of universal IR evaluation points (P,R,F,M) fell short of his goal: his universal IR surface equation did not suffice in and of itself, and his continuous extension argument was insufficient to find all the remaining points (quadruples). Egghe found only two extra universal IR evaluation points, (1,1,0,0) and (0,0,1,1), but it turns out that a total of 15 additional, valid, universal IR evaluation points exist. The gap first appeared in Egghe’s earliest paper and was carried into subsequent papers. The mathematical method used here for finding the additional universal IR evaluation points involves defining the relevance metrics P,R,F,M in terms of the Swets variables a,b,c,d. Then the maximum possible number of additional quadruples is deduced, and finally, all the invalid quadruples are eliminated so that only the valid, universal IR points remain. Six of these points may be interpreted as being continuous extensions of the universal IR surface, while the other nine points may be interpreted as being “off the universal IR surface.” This completely solves the problem of finding the maximum range possible of universal IR evaluation points.