Acute ergogenic effects of repetitive maximal breath-holding maneuvers on hematological and physiological responses: a graded exercise test investigation.

PURPOSE: Repetitive maximal breath-holds (BHs or apneas) have been noted to induce advantageous hematological and blood buffering changes. Building on this, the hypothesis was formulated that the execution of repeated maximal BH efforts might lead to subsequent enhancements in performance during a time-to-exhaustion test. METHODS: This study investigated the acute effects of five static maximal breath-holding maneuvers conducted with face immersion in cold water (10 °C) on subsequent graded exercise test (GET) performance. Seventeen well-trained participants completed a GET on a motorized treadmill under two randomized cross-over conditions: baseline measurement (CON) and after five repeated maximal breath-holding efforts (EXP). RESULTS: The GET protocol consists of incremental increases in speed until exhaustion. After the fifth breath-hold, participants in the EXP condition exhibited significant (P < 0.05) increases in hematocrit, hemoglobin concentration, red blood cell count, and muscle deoxygenation, accompanied by a reduction in blood lactate concentration (4.09 ± 2.21%, 3.9 ± 1.76%, 3.96 ± 2.1%, 81.48 ± 23.83%, and 15.22 ± 17.64%, respectively), compared to CON. During GET, the EXP condition showed a significantly (P < 0.05) delayed onset time of the second ventilatory threshold (3.14 ± 5.85%) and (P < 0.05) increased time to exhaustion (0.75 ± 1.02%). CONCLUSION: This evidence suggests that repeated maximal static breath-holding maneuvers enhance the oxygen delivery system by increasing the circulation of reserve red blood cells, heightened muscle oxygen deoxygenation, enhanced aerobic metabolism utilization, and postponing the transition from aerobic to anaerobic metabolism, implying a potential ergogenic effect. While pre-exercise breath-holding shows promise for improving time-to-exhaustion and optimizing subsequent distance running performance, further in-depth investigation is essential to fully elucidate the underlying mechanistic factors.

Arterial Function after a 246 km Ultra-marathon Running Race.

There is little research about the effects of ultra-endurance exercise on arterial morphological and functional properties. The aim was to assess the acute changes of the carotid-femoral pulse wave velocity and carotid doppler-derived parameters following an ultra-marathon race as well as the intima-media thickness of the carotid artery in ultra-marathon runners. Twenty athletes were examined at baseline and within 10 mins after a 246 km running race. Measurements included carotid-femoral pulse wave velocity, peak-systolic and end-diastolic velocities of carotid artery blood flow, pulsatility and resistivity indices and blood biochemical parameters. The intima-media thickness of the right and left carotid artery was measured before the race. Arterial stiffness and carotid artery intima media thickness at rest remained within known normal limits. The ultra-marathon race significantly increased carotid-femoral pulse wave velocity by 22.6% and pulsatility index by 10.2%. There was a decrease in body weight by 3.35% and an increase of all biochemical markers of muscle damage after the race. Additionally, C-reactive protein was correlated with both pulsatility and resistivity indices post-race. This study shows that immediately after a 246 km ultra-marathon running race, acute increase of arterial stiffness and vascular resistance were evident. The carotid artery thickness of ultra-marathon runners was within normal range.

Correlation of Fiber-Type Composition and Sprint Performance in Youth Soccer Players.

Metaxas, T, Mandroukas, A, Michailidis, Y, Koutlianos, N, Christoulas, K, and Ekblom, B. Correlation of fiber-type composition and sprint performance in youth soccer players. J Strength Cond Res 33(10): 2629-2634, 2019-The aim of this study was to examine the correlation between muscle fiber type and sprint performance in elite young soccer players of different age groups of the same team. Twenty-eight young players participated in this study (group U15, n = 8; group U13, n = 9; and group U11, n = 11). Anthropometric assessments, acceleration (10 m), and Bangsbo modified sprint test (30 m) were performed. Muscle biopsies were obtained from the vastus lateralis, and after that, fiber-type composition was determined by immunohistochemistry. No significant correlations were found between the sprint test and muscle fiber distribution for the groups U13 and U11 (p > 0.05). Also, no correlations were found between cross-sectional areas in the types of fibers with the sprint test in all groups (p > 0.05). A positive correlation was found between type I fibers and the performance in the acceleration test (10 m) (r = 0.77, p < 0.05) was found only in group U15 and a negative correlation between type IIA fibers and the performance in the acceleration test (10 m) (r = -0.89, p < 0.05). The correlations were observed only in group U15, which may indicate that the duration and the intensity of the soccer systematic training can affect the plasticity of the muscle fibers. Specific soccer training in youth is one of the factors that can affect fiber-type plasticity. The specific training programs and status of U15 are more intensive, and the exercises are oriented more to improve physical fitness.

The Effect of Fatigue on Electromyographic Characteristics during Obstacle Crossing of Different Heights in Young Adults.

The aim of this study was to investigate the effect of fatigue on electromyographic (EMG) parameters of healthy young adults during obstacle crossing of two different heights. Twelve untrained male adults (23 ± 5 years of age) were fatigued running on a treadmill with increasing speed and inclination and walked over an obstacle with a height set at 10% and 20% of each individual's lower limb length. Maximal plantar flexor torque and EMG of the medial gastrocnemius, soleus, and tibialis anterior muscles of the trailing limb were assessed during obstacle crossing. Data were captured before, immediately after and 5 minutes after a fatigue session. Fatigue induced significant reduction on the plantar flexor torque output immediately after and 5 minutes after exhaustion. After fatigue gait speed was not affected, the minimum distance between the obstacle and the trailing or leading foot remained unchanged, and the trailing foot contacted the ground closer to the obstacle immediately after fatigue. Regarding the EMG, medial gastrocnemius became after fatigue more active during swing phase when increasing the obstacle height, whereas this was not the case before or 5 minutes after fatigue. No other significant difference was observed for any of the examined muscles. It is concluded that the assessed fatigue protocol induced only minimal changes in the EMG activity of the examined muscles during obstacle crossing. Therefore, it is suggested that the neuromuscular system of healthy young individuals is able to respond to the decreased force capacity after fatigue during obstacle crossing of heights up to the 20% of the limb length. Key PointsExhaustion after running on a treadmill induces significant reduction in plantar flexion strength and changes in the positioning of the feet relative to the obstacle during obstacle crossing.EMG activity of the calf muscles of the trailing limb does not change significantly after fatigue during the stance phaseDuring swing phase, medial gastrocnemius EMG activity of the trailing limb increases after fatigue when obstacle height increases.These minor changes in EMG after fatigue, reveals that untrained, healthy, young subjects may compensate the deficit in muscular force due to fatigue when performing obstacle crossing.

Acute effect of dry needling on trunk kinematics and balance of patients with non-specific low back pain.

BACKGROUND: Limited knowledge exists about the effectiveness of dry needling (DN) concerning the torso kinematics in patients with non-specific low back pain (NS-LBP). Acute effects of DN in NS-LBP patients from a functional perspective were investigated. METHODS: Sixteen NS-LBP patients and 11 healthy individuals (HG) were examined. NS-LBP patients received a single session of DN at the lumbar region. Baseline and immediate post-treatment measurements during flexion-extension and lateral bending of the trunk were conducted for the NS-LBP patients. HG were measured only at baseline to be used as a reference of NS-LBP patients' initial condition. Algometry was applied in NS-LBP patients. Centre of pressure, range of motion of the trunk and its' derivatives were obtained. FINDINGS: HG performed significantly faster, smoother and with greater mobility in the performed tasks compared to the pre intervention measurements of the NS-LBP patients. For the NS-LBP patients, significant greater angular velocity in frontal plane and significant lower jerk in the sagittal plane were demonstrated post intervention. DN alleviated pain tolerance significantly at the L5 level. Regarding the effectiveness of the DN upon spine kinematics, their derivatives were more sensitive. INTERPRETATION: It appeared that the pathological type of torso movement was acutely affected by DN. NS-LBP patients showcased smoother movement immediately after the intervention and better control as imprinted in the higher derivative of motion although range of motion did not improve. This quantitative variable may not be subjected to acute effects of DN but rather need additional time and training to be improved.

Shoulder Pain and Trunk Muscles Endurance in Young Male and Female Swimmers.

Shoulder pain is a common syndrome in swimming and affects a large number of competitive swimmers. The purpose of the study was to investigate the relationship between pain in the shoulder girdle and the endurance of the trunk muscles in young swimmers. A total of 24 boys and 22 girls, aged 13 to 18 years, participated in the study. The measurements included the completion of a questionnaire (Shoulder Pain and Disability Index, SPADI) and a field test (McGill's Torso Muscular Endurance Test). The total SPADI score correlated weakly and negatively with the endurance time of back muscles in both sexes (r2 = 0.10, p = 0.035), and moderately and negatively in girls (r2 = 0.23, p = 0.023). A weak negative correlation was found between the disability index and the back muscles' endurance time in both sexes (r2 = 0.15, p = 0.007), which was moderate in girls only (r2 = 0.25, p = 0.019). The disability index displayed moderate negative correlations with the right oblique's (r2 = 0.18, p = 0.049) and left oblique's endurance time (r2 = 0.23, p = 0.024) in girls. Weight, body mass index, the total out-of-water training time per week and age significantly affected the endurance times of the trunk muscles in boys and girls (p < 0.05). In conclusion, strengthening the dorsal and the oblique muscles could reduce shoulder pain and disability in young swimmers and especially girls.

Repeated sprint ability in young football players according to the position and formation of the team: the effect of a specific training program.

BACKGROUND: The aim of this study was to investigate the effect of a specific training program for 12-weeks (twice a week) on the repeated sprint ability (RSA), according to the position of the football player in the formation of the team. METHODS: Two groups of U-17 football players (experimental-group, N.=22 and control-group, N.=19) and five positions (central-defenders, wide-defenders, central-midfielders, wingers, and central-attackers) according to the position in the formation (1-4-3-3) were studied. Sexual maturation was classified according to Tanner's stages. RSA and isokinetic strength were measured pre- and after the training program. RESULTS: The results showed that in RSA were differences in the factor time in the best (F=9.316, η2=0.383, P=0.008) and mean time (F=8.002, η2=0.348, P=0.013), but there were no differences between the groups. In strength, differences were observed in the time, mostly in the extensors at the three angular velocities (60°, 180°, 300°·sec-1) with differences in the group only in the maximum force (F=8.090, η2=0.366, P=0.013). No differences between players' positions were observed. CONCLUSIONS: A specific training program seems to affect players' performance on repeated sprint ability and the specific training in the players' position according to the team formation has a positive effect on the muscle power of football players.

An echocardiographic study of acute, progressive cardiac changes following a 246 km running race.

We describe the case of an ultra-marathon runner who finished first the "Spartathlon", a 246 km running race. The finishing time was the second fastest time ever in "Spartathlon". After finishing the race, the athlete suffered non-cardiac syncope and was administered intravenously 3 L of fluids for 5 hours. He underwent two echocardiographic assessments, one immediately after the finish of the race and the second 5 h later. Post-exercise fluid administration led to an increase in dimensions of all cardiac cavities, accompanied by a decrease in left ventricular (LV) end-diastolic interventricular septum thickness and posterior wall thickness of 0.1 cm. Dimensions and the respiratory profile of inferior vena cava improved after the race, reflecting alleviation of exercise-related hypovolaemia. Additionaly, LV global longitudinal strain improved, but right ventricular (RV) systolic function continued to deteriorate, mainly due to impairment of basal and medial RV free wall longitudinal strain. Study of this case offers a unique model for understanding the successive changes of cardiac structure and function following an ultra-marathon running race.

Left Ventricular Diastolic Response to Isometric Handgrip Exercise in Physically Active and Sedentary Individuals.

Aims: This study aims to investigate the diastolic left ventricular (LV) response to isometric handgrip exercise among healthy middle-aged men with high physical activity levels, versus matched sedentary individuals. Methods: Two groups of 10 men aged 41−51 years were studied. Men in the first group had high weekly self-reported physical activity levels (>3000 METs × min/week). In comparison, men in the second group reported low physical activity levels (<300 METs × min/week). An isometric handgrip exercise (IHE) stress echocardiography test was performed in all of them. Results: Both groups showed a similar and statistically significant increase in heart rate, systolic, diastolic, and mean arterial pressure following IHE. The group of active men under study did not show a statistically significant change in the ratio of early diastolic mitral valve inflow velocity to early diastolic lateral wall tissue velocity (E/e' ratio) in response to IHE. Conversely, the inactive participants' E/e' ratio was higher at peak activity in the isometric handgrip exercise. Conclusions: Apparently, healthy middle-aged men with high levels of physical activity seem to have an improved lusitropic cardiac function compared to men with low levels of physical activity, as observed by the different diastolic LV responses induced by isometric handgrip exercise.

Correlation between Cardiopulmonary Indices and Running Performance in a 14.5 km Endurance Running Event.

BACKGROUND: Running is a common recreational activity, and the number of long-distance-race participants is continuously growing. It is well-established that regular physical activity can prevent and manage non-communicable diseases and benefit public health. Training for a long-distance race requires development of specific aerobic abilities and should generate the desired race performance. The purpose of this study was to support the training design and motivation of recreational endurance runners, by investigating whether a 14.5 km race performance of long-distance runners correlates with their cardiopulmonary indices measured in the laboratory. METHODS: To examine the relationships of a 14.5 km running performance with the cardiopulmonary parameters of amateur runners, a cross-sectional study design was applied. Fifteen (eleven men and four women) recreational long-distance runners (aged 41.3 ± 9.2 years) from Northern Greece were included in the study and were evaluated in the laboratory within one week before an endurance running race-the 14.5 km Philip Road race, in Greece. The laboratory-based examinations of the athletes consisted of a comprehensive medical pre-participation screening and maximal cardiopulmonary exercise testing. RESULTS: The results showed that the 14.5 km race performance time (73.8 ± 9.7 min) significantly correlated with the cardiopulmonary-exercise-testing speed-related indices at specific submaximal and maximal workloads (p < 0.01, p < 0.05), while the cardiopulmonary indices of oxygen uptake did not reliably predict race running time (p > 0.05). CONCLUSIONS: There is a better correlation of the 14.5 km running performance of recreational long-distance runners with the cardiopulmonary-exercise-testing speed-related indices at specific workloads than with the indices of oxygen uptake, running economy or respiratory economy. When preparing a training strategy, amateur long-distance runners should mostly rely on specific running-speed-related laboratory data rather than on oxygen-uptake values.

Cardiovascular effects of doping substances, commonly prescribed medications and ergogenic aids in relation to sports: a position statement of the sport cardiology and exercise nucleus of the European Association of Preventive Cardiology.

The use of substances and medications with potential cardiovascular effects among those practicing sports and physical activity has progressively increased in recent years. This is also connected to the promotion of physical activity and exercise as core aspects of a healthy lifestyle, which has led also to an increase in sport participation across all ages. In this context, three main users' categories can be identified, (i) professional and amateur athletes using substances to enhance their performance, (ii) people with chronic conditions, which include physical activity and sport in their therapeutic plan, in association with prescribed medications, and (iii) athletes and young individuals using supplements or ergogenic aids to integrate their diet or obtaining a cognitive enhancement effect. All the substances used for these purposes have been reported to have side effects, among whom the cardiovascular consequences are the most dangerous and could lead to cardiac events. The cardiovascular effect depends on the type of substance, the amount, the duration of use, and the individual response to the substances, considering the great variability in responses. This Position Paper reviews the recent literature and represents an update to the previously published Position Paper published in 2006. The objective is to inform physicians, athletes, coaches, and those participating in sport for a health enhancement purpose, about the adverse cardiovascular effects of doping substances, commonly prescribed medications and ergogenic aids, when associated with sport and exercise.

Impact of a 246 Km ultra-marathon running race on heart: Insights from advanced deformation analysis.

Although previous studies suggest that prolonged intense exercise such as marathon running transitorily alters cardiac function, there is little information regarding ultramarathon races. Aim of this study was to investigate the acute impact of ultra-endurance exercise (UEE) on heart, applying advanced strain imaging. Echocardiographic assessment was performed the day before and at the finish line of "Spartathlon": A 246 Km ultra-marathon running race. 2D speckle-tracking echocardiography was performed in all four chambers, evaluating longitudinal strain (LS) for both ventricles and atria. Peak strain values and temporal parameters adjusted for heart rate were extracted from the derived curves. Out of 60 participants initially screened, 27 athletes (19 male, age 45 ± 7 years) finished the race in 33:34:27(28:50:38-35:07:07) hours. Absolute values of right (RV) and left ventricular (LV) LS (RVLS -22.9 ± 3.6 pre- to -21.2 ± 3.0% post-, p=0.04 and LVLS -20.9 ± 2.3 pre- to -18.8 ± 2.0 post-, p=0.009) slightly decreased post-race, whereas atrial strain did not change. RV and LV LS decrease was caused mainly by strain impairment of basal regions with apical preservation. Inter-chamber relationships assessed through RV/LV, LV/LA, RV/RA and RA/LA peak values' ratios remained unchanged from pre to post-race. Finally, UEE caused an extension of the systolic phase of cardiac cycle with concomitant diastole reduction (p<0.001 for all strain curves). Conclusively, ventricular LS strain as well as effective diastolic period slightly decreased, whereas atrial strain and inter-chamber relationships remained unchanged after running a 246-km-ultra-marathon race. These changes may be attributed to concomitant pre- and afterload alterations following UEE.

Effects of long-term exercise training on cardiac baroreflex sensitivity in patients with coronary artery disease: a randomized controlled trial.

OBJECTIVE: To investigate whether a structured long-term exercise training programme in patients with coronary artery disease affects baroreflex function and cardiorespiratory efficiency. PATIENTS: Twenty-five elderly male patients with coronary artery disease. METHODS: The patients were randomized into exercise (group A) or control group (group B). Group A followed a seven-month supervised exercise programme, consisting of three sessions of aerobic interval training weekly at moderate intensity. Twenty patients completed the study (group A: 10 patients and group B: 10 patients). At the beginning and end of the study, all subjects underwent a tilt test for the baroreflex sensitivity assessment and a graded exercise treadmill test with spiroergometry for the evaluation of their cardiorespiratory efficiency. RESULTS: There were no differences between the two groups for any baseline variable. After training in group A, peak oxygen consumption, maximal treadmill tolerance time and anaerobic threshold were significantly increased by 21.9% (P < 0.001), 19.8% (P < 0.001) and 18.6% (P < 0.05), respectively. There were also significant increases in baroreflex sensitivity by 21.2% (P < 0.01), in baroreflex effectiveness index by 23.9% (P < 0.01), in event count by 45.1% (P < 0.01) and in ramp count by 13.2% (P < 0.05). Moreover, significant correlations were observed between the autonomic and cardiorespiratory parameters in group A at the end. CONCLUSION: The results suggest that long-term exercise training leads to beneficial effects on baroreflex activity and cardiorespiratory performance in coronary patients, and thus could constitute an efficient nonpharmacological intervention in this population.

Comparative study of cardiorespiratory adaptations in elite basketball players of different age groups.

BACKGROUND: Systematic training of basketball causes morphological cardiac and cardiorespiratory adaptations. Previous studies have mainly focused either on only cardiac or respiratory changes. However, the extent of these cardiac adaptations and their relationship with aerobic capacity remain unclear in basketball athletes of different ages. METHODS: Eighty male basketball players participated in the experimental group and 80 healthy and sedentary male individuals served as controls. All participants underwent to athletic history, anthropometric measurements, 12-lead resting electrocardiogram (ECG), echocardiography, resting spirometry and cardiopulmonary exercise stress test. RESULTS: Left ventricular mass (LVM), left ventricular mass index (LVMI), left ventricular end-diastolic internal dimension (LVIDd), end-diastolic volume (EDV), stroke volume (SV) and interventricular septal thickness at diastole (IVSd) were significantly higher in all groups of athletes compared to controls (P<0.05). End-diastolic volume index (EDVI) was significantly higher only in adult players compared to controls (P<0.05). Posterior wall thickness at diastole (PWd) was significantly greater in groups of children and adult players compared to controls (P<0.05). Maximal oxygen uptake (V̇O2max) in relative values was higher in all groups of athletes compared to controls (P<0.05). CONCLUSIONS: The increased LVM is attributed to concentric hypertrophy. This is further supported by the finding that there was no relationship between V̇O2max and echo parameters. The results of the present study indicate that the cardiorespiratory adaptations caused by basketball training are mainly formed at the early age stages without further increase throughout the years of action.

Identification of Good Practices in Long-Term Exercise-Based Rehabilitation Programs in Stroke Patients.

Physical activity is an important factor for primary and secondary stroke prevention. The process of stroke rehabilitation includes early and late physical activity and exercise, which prevents further stoke and improve patients' quality of life. MY WAY project, an ERASMUS+ SPORT program, is aimed at analyzing and developing or transferring best innovative practices related to physical activity and exercise enhancing health in poststroke patients. The aim of the study was to identify, analyze, and present the good practices and strategies to encourage participation in sport and physical activity and engage and motivate chronic stroke patients to perform physical activity changing their lifestyle and to maintain a high adherence to long-term exercise-based rehabilitation programs. Our results demonstrated that unified European stroke long-term exercise-based rehabilitation guidelines do not exist. It seems that low training frequency with high aerobic exercise intensity may be optimal for improved physical performance and quality of life in combination with a high adherence. It is important to optimize the training protocols suitable for each patient. The continuous education and training of the specialized professionals in this field and the presence of adequate structures and cooperation between different healthcare centers are important contributors. The clear objective for each country should be to systematically make the necessary steps to enhance overall exercise-based stroke rehabilitation attendance in the long term. Long-term interventions to support the importance of physical exercise and lifelong exercise-based rehabilitation in chronic stroke patients should be created, what coincides with the goal of the MY WAY project.

Exploring the determinants of the cardiac changes after ultra-long duration exercise: The echocardiographic Spartathlon study.

AIM: The investigation of the pathophysiological determinants of cardiac changes following ultra-long duration exercise. METHODS: Twenty-seven runners who finished a 246 km running race were examined both before and after the finish of the race. Examinations included echocardiography and measurement of body weight and blood biochemical parameters. RESULTS: Exercise increased left ventricular end-diastolic interventricular septum thickness (LVIVSd) (p < 0.001) and posterior wall thickness (LVPWTd) (p = 0.001) and right ventricular end-diastolic area (p = 0.005), while reduced tricuspid annular plane systolic excursion (TAPSE) (p = 0.004). A minor decrease in the peak absolute values of both left ventricular (from -20.9 ± 2.3% to -18.8 ± 2.0%, p = 0.009) and right ventricular (from -22.9 ± 3.6% to -21.2 ± 3.0%, p = 0.040) global longitudinal strains occurred. There was decrease in body weight (p < 0.001) and increase in both circulating high-sensitivity troponin I (p = 0.028) and amino-terminal pro-B type natriuretic peptide (NT-proBNP) (p = 0.018). The change in the sum of LVIVSd and LVPWTd correlated negatively with percentage change of body weight (r = -0.416, p = 0.049). The only independent determinant of post-exercise NT-proBNP was pulmonary artery systolic pressure (r = 0.797, p = 0.002). Post-exercise NT-proBNP correlated positively with percentage changes of basal (RVbas) (r = 0.582, p = 0.037) and mid-cavity (RVmid) (r = 0.618, p = 0.043) right ventricular diameters and negatively with percentage change of TAPSE (r = -0.720, p = 0.008). Similar correlations with RVbas, RVmid and TAPSE were found for pulmonary artery systolic pressure. Post-exercise high-sensitivity troponin I correlated negatively with percentage change of body weight (r = -0.601, p = 0.039), but was not associated with any cardiac parameter. CONCLUSION: The main cardiac effects of ultra-long duration exercise were the decrease in left ventricular end-diastolic dimensions and increase in left ventricular wall thickness, as well as minimal dilatation and alteration in systolic function of right ventricle, possibly due to the altered exercise-related right ventricular afterload.

Arterial adaptations in athletes of dynamic and static sports disciplines - a pilot study.

BACKGROUND: Structural and functional arterial adaptations with regard to the type and level of training in young athletes are understudied. Our research aimed at evaluating them in two types of exercise (dynamic and static) and two levels of engagement (high and recreational). METHODS: A total of 76 volunteers formed five groups. Group A included 17 high-level dynamic sports athletes 30·9 ± 6·4 years old, group B 14 recreational ones aged 28·7 ± 6·2 years, group C 15 high-level static sports athletes 26·4 ± 3·9 years old and group D 16 recreational ones, aged 25·8 ± 4·8 years. Fourteen sedentary men 30 ± 3·8 years old formed control group E. Structural indices of left cardiac chambers and thoracic aorta were echographically obtained, as well as common carotid intima-media thickness (cIMT). Furthermore, applanation tonometry was conducted, at rest and during a handgrip strength test, for the acquisition of central arterial pressure parameters, carotid-femoral pulse wave velocity (cfPWV) and total arterial compliance (Cτ ). RESULTS: No significant differences in structural arterial markers were observed. However, group A obtained the highest handgrip central systolic pressure values (13·1% compared to group D, P<0·05). Resting cfPWV was lower in group B by 13·8% (P<0·05) than C and by 16·7% (P<0·01) than E, whereas Cτ was higher in group Β by 33·3% than C (P<0·05) and by 40·9% than E (P<0·01). CONCLUSION: Functional arterial exercise-induced adaptations become apparent at an early age, without being in conjunction with structural ones. Recreational dynamic exercise results in the most favourable arterial characteristics.

Pathophysiological mechanisms of noncardiac syncope in athletes.

OBJECTIVE: The investigation of the differences in orthostatic responses of individuals with a history of noncardiac syncope(NCS) between athletes and nonathletes. METHODS: A passive tilt test for 30min was performed in 133 athletes (54 with NCS, 79 without NCS) and 48 nonathletes (15 with NCS, 33 without NCS). We performed measurement of haemodynamic, heart rate variability and baroreflex sensitivity parameters. All comparisons were adjusted for age, gender and body mass index(BMI). RESULTS: Athletes with NCS had increased heart rate(HR) (90±11 vs 81±10bpm, p=0.001) and decreased total peripheral resistance index(TPRI) (2227±408 vs 2918±733dynesm2/cm5, p=0.039) and baroreflex effectiveness index(BEI) [70.16(37.42-89.71) vs 72.19(48.49-91.35)%, p=0.016] compared with athletes without NCS. After applying backward stepwise logistic regression analysis to predict history of NCS in athletes, the final model included age, gender, BMI, HR and TPRI. Nonathletes with NCS had increased HR (95±24 vs 83±11bpm, p=0.024) and TPRI (3744±1606 vs 2937±880dynesm2/cm5, p=0.030) and decreased stroke index(SI) (25.4±7.6 vs 33.0±7.5mL/m2, p=0.003) compared with nonathletes without NCS. After applying backward stepwise logistic regression analysis to predict history of NCS in nonathletes, the final model included SI and HR. Among individuals with NCS, athletes had increased SI and BEI and decreased HR and TPRI compared with nonathletes. Among individuals without NCS, a positive result of tilt test was less frequent in athletes compared with nonathletes (p=0.031). CONCLUSIONS: The possible main underlying mechanism for NCS during upright standing in athletes is the decreased TPRI, while the inadequate preservation of SI in nonathletes.

Eighteen years' experience applying old and current strategies in the pre-participation cardiovascular screening of athletes.

INTRODUCTION: Cardiovascular pre-participation screening (PPS) is recommended for the identification of athletes at risk for sudden cardiac death. However, there is currently no universally accepted screening protocol. METHODS: Two distinct PPS strategies were studied in a large cohort of Greek athletes (5 to 39 years old): PPS I, with routine 12-lead ECG and echo, in addition to personal and family history, and physical examination; and PPS II, without routine echo. PPS I (12,353 athletes) was performed from 1992 to 2002, and PPS II (9852 athletes) from 2003 to 2010. RESULTS: "Abnormal" findings were observed in 49.3% of the athletes (49.6% in PPS I and 48.9% in PPS II, p=0.299). Most of them were age- or exercise-related. Further evaluation was recommended for 8.3% of the athletes. Finally, 39 athletes (22 from PPS I) were excluded from competitive sports. Hypertrophic cardiomyopathy was found in 7 athletes. Other abnormalities were: dilated cardiomyopathy; complete heart block; coronary artery disease; Wolf-Parkinson-White syndrome; and severe hypertension. The ECG played a critical role in the exclusion of 13 athletes, compared to only one for echo. Both PPS methods revealed an almost equal incidence of findings. CONCLUSIONS: We suggest that the routine use of ECG alone is sufficient for the successful screening of athletes.

Fatigue and recovery in children and adults during sustained contractions at 2 different submaximal intensities.

The purpose of this study was to examine the effects of submaximal sustained contractions on fatigue and recovery properties in untrained prepubescent boys (n = 14) and men (n = 14). All participants performed, in random order, an isometric plantar flexion at 20% and 60% of their maximal voluntary contraction (MVC) until exhaustion (20%fatigue and 60%fatigue, respectively). During both fatigue protocols, surface electromyogram (sEMG) of the soleus and tibialis anterior muscles was recorded. Before and after the fatigue protocol, MVCs and blood lactate concentration were obtained. During 20%fatigue and 60%fatigue, agonist and antagonist sEMG increased gradually to a similar extent in both groups. Immediately after fatigue, MVC torque decreased in both groups, compared with prefatigue values, and boys recovered faster than men in both fatigue protocols. The reduction in agonist sEMG during MVC after fatigue was not significantly different between men and boys (p < 0.05), independent of the fatigue protocol. sEMG of boys recovered to baseline values 3 min after the 20%fatigue and 60%fatigue protocols, whereas men did not recover. Lactate concentration increased immediately after the end of the fatigue protocols, compared with the prefatigue values (p < 0.05). This increase was higher for the 60%fatigue than for 20%fatigue protocol, and did not differ between boys and men. It is concluded that low- and middle-intensity submaximal sustained isometric fatigue protocols induce similar fatigue effects in boys and men. Furthermore, it was shown that boys can recover faster than men, independent of the contraction intensity that induces fatigue.