Screening young athletes for prevention of sudden cardiac death: Practical recommendations for sports physicians.

Regular intensive exercise in athletes increases the relative risk of sudden cardiac death (SCD) compared with the relatively sedentary population. Most cases of SCD are due to silent cardiovascular diseases, and pre-participation screening of athletes at risk of SCD is thus of major importance. However, medical guidelines and recommendations differ widely between countries. In Italy, the National Health System recommends pre-participation screening for all competitive athletes including personal and family history, a physical examination, and a resting 12-lead electrocardiogram (ECG). In the United States, the American College of Cardiology and the American Heart Association recommend a pre-participation screening program limited to the use of specific questionnaires and a clinical examination. The value of a 12-lead ECG is debated based on issues surrounding cost-efficiency and feasibility. The aim of this review was to focus on (i) the incidence rate of cardiac diseases in relation to SCD; (ii) the value of conducting a questionnaire and a physical examination; (iii) the value of a 12-lead resting ECG; (iv) the importance of other cardiac evaluations in the prevention of SCD; and (v) the best practice for pre-participation screening.

Prevalence of electrocardiographic abnormalities in West-Asian and African male athletes.

OBJECTIVES: To evaluate the electrocardiographic (ECG) characteristics of West-Asian, black and Caucasian male athletes competing in Qatar using the 2010 recommendations for 12-lead ECG interpretation by the European Society of Cardiology (ESC). DESIGN: Cardiovascular screening with resting 12-lead ECG analysis of 1220 national level athletes (800 West-Asian, 300 black and 120 Caucasian) and 135 West-Asian controls was performed. RESULTS: Ten per cent of athletes presented with 'uncommon' ECG findings. Black African descent was an independent predictor of 'uncommon' ECG changes when compared with West-Asian and Caucasian athletes (p<0.001). Black athletes also demonstrated a significantly greater prevalence of lateral T-wave inversions than both West-Asian and Caucasian athletes (6.1% vs 1.6% and 0%, p<0.05). The rate of 'uncommon' ECG changes between West-Asian and Caucasian athletes was comparable (7.9% vs 5.8%, p>0.05). Seven athletes (0.6%) were identified with a disease associated with sudden death; this prevalence was two times higher in black athletes than in West-Asian athletes (1% vs 0.5%), and no cases were reported in Caucasian athletes and West-Asian controls. Eighteen West-Asian and black athletes were identified with repolarisation abnormalities suggestive of a cardiomyopathy, but ultimately, none were diagnosed with a cardiac disease. CONCLUSION: West-Asian and Caucasian athletes demonstrate comparable rates of ECG findings. Black African ethnicity is positively associated with increased frequencies of 'uncommon' ECG traits. Future work should examine the genetic mechanisms behind ECG and myocardial adaptations in athletes of diverse ethnicity, aiding in the clinical differentiation between physiological remodelling and potential cardiomyopathy or ion channel disorders.

The relations between physical ability and bone mass in women aged over 65 years.

In this cross-sectional study of 55 women (mean age 73.54 +/- 5.87), the magnitude of the relation between different indices of physical ability and confounding factors to bone density were determined. Physical fitness was assessed by direct measurement of maximal oxygen consumption (VO2 max), isokinetic muscle strength, and quadriceps and psoas muscle surfaces and densities using computed tomography. Anthropometry, chronological and gynecological ages, and dietary calcium intake were also recorded. The bone mineral density (BMD) was evaluated at the axial level (lumbar spine and proximal femur) and at the peripheral level (radius and tibia, cancellous and cortical compartments). Parameters related to physical ability proved to be the best predictors of BMD in radial and tibial cancellous compartments, spine, femoral neck, and trochanter, accounting for 15-27.5% of the total variance. The VO2 max was a major determinant of the femoral mineral density and one of the predictors of radial and tibial cancellous compartments. Psoas parameters were strongly related to spine mineral density and also constituted a predictor of radius (cancellous) and tibia mineral densities. The arm muscle strength could predict, though weakly, the BMD of axial skeleton, whereas thigh muscle strength only predicted the BMD of inferior limbs. No correlation was observed between current dietary calcium intake and BMD. Age-postmenopause and fertile life remained predictive of BMD at mostly cancellous sites, whereas anthropometry exerted important effects on radial and tibial cortices. The study suggests distinct sets of relations between physical ability and the BMD variables. Subjects with greater and denser psoas muscles had greater spine BMD, and those with higher VO2 max had greater proximal femur BMD.

Anaemia and iron deficiency in athletes. Practical recommendations for treatment.

Trained athletes frequently experience low levels of blood haemoglobin (13 to 14 g/100ml in men and 12 g/100ml in women) plus low haematocrit and low ferritin levels. These parameters define the concept of 'sports anaemia'. Low iron levels may be due to mechanical haemolysis, intestinal bleeding, haematuria, sweating, low iron intake or poor intestinal absorption. The resulting decrease in blood gas transport and muscle enzyme activity impairs performance. The concept of sports anaemia can be criticised. Simply measuring the blood levels does not take into account the haemodilution that occurs in athletes because of training. The lack of these measurements makes it difficult to diagnose anaemia or evaluate any treatment. Anaemia is treated by preventing decreased iron stores through a balanced food intake or iron supplements. Self-medications must be discouraged because of intolerance, risk of overdose and many other drug interactions.

Performance and drag during drafting swimming in highly trained triathletes.

PURPOSE: The influence of drafting was studied on the swimming performance, metabolic response, and passive drag of eight triathletes. METHODS: The performance in drafting position was measured directly behind another swimmer during a 400-m swim and compared with the nondrafting position. Metabolic response concerned VO(2), blood lactate, stroke rate, stroke length, and rating of perceived exertion. Drag was measured by passive towing. RESULTS: In drafting position, the triathletes swam on average faster (3.2%) over the 400-m swim than in nondrafting position (4 min, 47.69 +/- 10.35 s vs 4 min, 57.25 +/- 7.24 s; P < 0.01). Blood lactate and stroke rate were significantly lower (9.6 mM vs 10.8 mM; 39.9 cyclexmin(-1) vs 41.3 cyclexmin(-1) P < 0.02) and stroke length higher (2.10 mx cycle(-1) vs 1.97 mxcycle(-1), P < 0.01) than in nondrafting position. VO(2) and rating of perceived exertion were not statistically different. Passive drag was lower in drafting than in nondrafting position (P < 0.01). However, the gain in drag decreased with the towed velocity (from 26% at 1.1 mxs(-1) to 13% at 1.7mxs(-1)). In drafting position, the performance gain was related to the 400-m time (r = 0.80, P < 0.01) and to the skinfold thickness (r = 0.94, P < 0.01), with faster and leaner swimmers having greater gains of performance. CONCLUSIONS: Swimming behind another swimmer in a race is advantageous for triathletes.

Electrical stimulation and swimming performance.

The purpose of the study was to examine the influence of a 3-wk period of electrostimulation training on the strength of the latissimus dorsi m. and the swimming performances of 14 competitive swimmers divided into 7 electrostimulated (EG) and 7 control swimmers (CG). The peak torques registered during the flexion-extension of the arm was determined with the help of an isokinetic dynamometer at different velocities (from -60 degrees.s(-1) to 360 degrees.s(-1)). Performances were measured over a 25-m pull buoy and a 50-m freestyle swim. For EG, a significant increase of the peak torques was measured in isometric, eccentric, and concentric conditions (P < 0.5). The swimming times declined significantly (P < 0.01) by 0.19 +/- 0.14 s, for the 25-m pull-buoy, and by 0.38 +/- 0.24 s, for the 50-m freestyle. For CG, no significant difference was found for any of the tests. For the whole group, the variations of the peak torques, measured in eccentric condition (-60 degrees.s(-1)) were related to the variations of the performances (r = 0.77; P < 0.01). These results showed that an electrostimulation program of the latissimus dorsi increased the strength and swimming performances of a group of competitive swimmers.

Creatine supplementation does not improve sprint performance in competitive swimmers.

This study was conducted to examine the effects of creatine (Cr) supplementation on sprint swimming performance and energy metabolism. Twenty highly trained swimmers (9 female, 11 male) were tested for blood ammonia and for blood lactate after the 25-, 50-, and 100-m performance in their best stroke on two occasions 7 d apart. After the first trial, subjects were evenly and randomly assigned to either a creatine (5 g creatine monohydrate 4 times per day for 5 d) or a placebo group (same dosage of a lactose placebo) in a double-blind research design. No significant differences in performance times were observed between trials. Post-exercise blood ammonia concentration decreased in the 50- and 100-m trials in the creatine group and in the 50-m trial in the placebo group. The supplementation period had no effect on post-exercise blood lactate. Therefore, creatine supplementation cannot be considered as an ergogenic aid for sprint performance in highly trained swimmers although adenine nucleotide degradation may be reduced during sprint exercise after 5 d of creatine ingestion.

Wet suit effect: a comparison between competitive swimmers and triathletes.

The purpose of the present investigation was to examine the wet suit effect on 8 swimmers and 8 triathletes. For swimmers, the performances of a 400-m swim with and without wet suit were not statistically different (4 min 12.5 +/- 8 s vs 4 min 13.9 +/- 4 s) while for triathletes the swim times were reduced by 19 s (4 min 45.8 +/- 34 s vs 5 min 04.7 +/- 30 s, P < 0.01). For swimmers, VO2max and blood lactate measured with the wet suit were lower than without (P < 0.01), while for triathletes stroke rate was significantly higher with the wet suit (P < 0.01). For the whole group, the individual differences of performance were related to the blood lactate differences (r = -0.68; P < 0.01) and to the hydrostatic lift (r = 0.63; P < 0.01). For swimmers, the energy cost of swimming and the gliding ability were not statistically different with or without wet suit, while for triathletes they were significantly lower and decreased with velocity. It is concluded that the wet suit effect improves performance more in inefficient swimmers with low buoyancy, swimming at low speeds.

A new tool for evaluating energy expenditure: the "QAPSE" development and validation.

The objective of this study was to design and validate a working tool for the objective evaluation of daily energy expenditure (DEE) by means of a simple, noninvasive method: the QAPSE (Saint-Etienne Physical Activity Questionnaire), a questionnaire about physical activity (PA) over a period of 7 d (168 h). This eight-page questionnaire is designed to provide a complete picture of the subject's habitual PA without any restriction concerning the activities investigated, nor any specialization in relation to health components. It investigates the five areas of PA during daily life: work or way of keeping occupied, leisure activity (sports and nonsports activities), housework, basic everyday activity, moving about from place to place. Assessment of physical activity was conducted in 115 healthy volunteer subjects of both sexes aged 20-88. The values of mean habitual daily energy expenditure (MHDEE) obtained varied between 6,510 and 24,331 kJ.d-1. The MHDEE were in agreement with the data reported in the literature for various groups differing in respect to level of activity, sex, and age. The study demonstrated the reproducibility of the QAPSE (r = 0.997; N = 20; P < 0.0001). Its validity was tested in a comparative study between MHDEE and caloric intake (r = 0.576; N = 20; P < 0.01).

Physiological aspects of swimming performance for persons with disabilities.

The purpose of this study was to evaluate the various factors involved in the performances of three groups of swimmers with disabilities. These factors were average VO2max (Av-VO2max) measured during swimming and gliding factors measured by the passive drag. Thirty-four swimmers with disabilities were assigned into three groups ranging from more disabilities to fewer disabilities. The first group (G I) included 13 subjects in wheelchairs, the second group (G II) 10 subjects walking with technical aids, and the third group (G III) 11 swimmers with disabilities walking without any help. For G I, the performances and Av-VO2max were lower (P < 0.05) than for G II and G III while the passive drag was higher than for G III (P < 0.05). The performances, Av-VO2max, and passive drag were not statistically different between G II and G III. Some of the swimmers had a pronounced amyotrophia of the lower extremities (i.e., reduced volume of inactive muscles). The height from the top of the head to the beginning of the bilateral amyotrophia was called "height without amyotrophia" (HWA). In the whole group, passive drag was not related to the mass or the height but to the ratio mass/HWA (r = 0.71, P < 0.01). However, within each group, passive drag was mainly related to the mass (r = 0.63, 0.78, 0.62, P < 0.01, for G I, G II, and G III respectively). Performances of a 100-m and 400-m swim were mainly related to Av-VO2peak (r = 0.81 and 0.79, P < 0.01, respectively).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of endurance training on postexercise parathyroid hormone levels in elderly men.

The present study was designed to evaluate the effects of 6-wk endurance training on serum parathyroid hormone (PTH) levels and on other parameters at rest and after a maximal exercise test (MET) in 24 55- to 73-yr-old men. Before training, MET was found to induce a significant increase in PTH levels as compared with resting values. This MET-induced rise in PTH was accompanied by enhanced total calcium, phosphate, alkaline phosphatase (ALP), osteocalcin, and albumin levels. After the training period (75-80% maximal heart rate, 1 h.d-1, 4 d.wk-1), the changes induced by MET in calcium, phosphate, ALP, and albumin levels followed the same pattern as before training. Conversely, the MET-induced increase in PTH levels was found markedly more pronounced after training than in untrained conditions (+21.9% vs +11.1%, respectively, P < 0.05). Furthermore, lower values of osteocalcin were found after training as compared with pretraining values, both at rest and after maximal exercise. These findings indicate that 6 wk of endurance training enhanced exercise-related release of PTH and reduced osteocalcin levels in elderly men. This might be of importance regarding bone status in the elderly, as exercise is proposed as a preventive measure against osteopenia.

Modeled responses to training and taper in competitive swimmers.

This study investigated the effect of training on performance and assessed the response to taper in elite swimmers (N = 18), using a mathematical model that links training with performance and estimates the negative and positive influences of training, NI and PI. Variations in training, performance, NI, and PI were studied during 3-, 4-, and 6-wk tapers. The fit between modeled and actual performance was significant for 17 subjects; r2 ranged from 0.45 to 0.85, P < 0.05. Training was progressively reduced during tapers. Performance improved during the first two tapers: 2.90 +/- 1.50% (P < 0.01) and 3.20 +/- 1.70% (P < 0.01). Performance improvement in the third taper was not significant (1.81 +/- 1.73%). NI was reduced during the first two tapers (P < 0.01 and P < 0.05, respectively), but not during the third. PI did not change significantly during tapers. Thus, the present results show that the model used is a valuable method to describe the effects of training on performance. Performance improvement during taper was attributed to a reduction in NI. PI did not improve with taper, but it was not compromised by the reduced training periods.

Estimation of performance potential of standardbred trotters from blood lactate concentrations measured in field conditions.

The purpose of this study was to examine the relationship between V4 (velocity which results in a blood lactate concentration of 4 mmol/l), age and racing performance of Standardbred trotters and to establish V4 normal values to select good and poor performers. The specific influence of racing (RT) and training (T1 and T2) tracks was also examined. A total of 159 horses were divided into 5 age-groups from 2 to 6 and over and performed 330 standardised exercise tests of 3 steps performed at increasing speeds. The velocity of the horses was measured with a tachometer on the sulky. Blood lactate concentrations were measured from the jugular vein after each step. For the 5 age-groups, mean V4 values increased significantly (P < 0.05) with age between 2 and 4 years. After 5 years, this increase was reduced and became nonsignificant. The highest V4 values were obtained on the racing track (RT) and the lowest on the training tracks (T1; P < 0.05). No significant difference was found between RT and T2 nor between T1 and T2. Horses were defined as good performers (GP) when finishing between the first and the fifth place in a race or poor performers (PP) when finishing lower than fifth. V4 was significantly higher for GP than for PP (P < 0.05). Normal value of V4 were established for good and poor performers taking into account the 95% confidence interval of the data. Therefore, V4 depends on age and track and can be considered an important parameter to evaluate trotters' racing potential.

Hematological responses to training and taper in competitive swimmers: relationships with performance.

The purpose of this study was to monitor hematological changes during 12 weeks of intense training and 4 weeks of taper in 8 highly trained competitive swimmers, and to assess the relationships between hematological variables and competition performance. Venous blood samples were obtained in the mid-season (wk 10), before taper (wk 22) and after taper (wk 26). Swimmers participated in actual competitions within 1 wk of each blood testing. Comparisons were made between swimmers improving performance with taper by more than 2% (n = 4), efficient (GE) or less than 2% (n = 4), less efficient (GLE). Hemoglobin (Hb), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH) and mean corpuscular hemoglobin concentration (MCHC) increased significantly during training. MCH and MCHC decreased during taper, while serum iron tended to increase (P = 0.07). Improvement in performance during taper was positively correlated with post-taper red cell count (RCC): r = 0.83, P < 0.05. GE swimmers had higher pre- and post-taper RCC, and post-taper Hb and hematocrit. In conclusion, intense training and taper appeared to influence the hematological status and performance capacity of the studied group of swimmers.

Effect of a 6-week endurance training programme and branched-chain amino acid supplementation on histomorphometric characteristics of aged human muscle.

The effects of a 6-week endurance training programme and a branched-chain amino acid (BCAA) supplementation were investigated on skeletal muscle histomorphometric characteristics of elderly men. Seventeen elderly men, age (63 +/- 5 years), height (173 +/- 5 cm) and weight (75 +/- 8 kg) were included in the study. One group (n = 9) received an oral BCAA supplementation for 6 weeks (16, 2 and 2 g per day of leucine, isoleucine and valine, respectively), while another group (n = 8) received a placebo. During these 6 weeks, subjects trained on a Monark cycle ergometer at 75 +/- 9% of their maximal heart rate for 1 h/day, 4 days/week. Muscle biopsy samples taken at rest before and after endurance training were analyzed for capillarization, fibre type distribution and fibre area. As a result of endurance training, maximal oxygen uptake was significantly increased by about 5% in control and BCAA supplemented groups (P < 0.01). The number of capillaries per fibre and in contact with type I fibres was significantly increased (P < 0.05), this effect being similar in control and BCAA supplemented groups. The percentage distribution and area of type I, type IIa and type IIb fibres did not differ between the two groups and remained unchanged with endurance training. It is concluded that skeletal muscle of elderly men can adapt to a 6-week endurance training programme and that a BCAA supplementation does not further enhance the induced histomorphometric changes.

[Maximal effort, maximal heart rate and serum lactic acid in exercise electrocardiography. A comparative study]. / Effort maximal, fréquence cardiaque maximale et lactacidémie en électrocardiographie d'effort. Etude comparative.

In exercise stress testing the quantification of effort on which the value and significance of the test depend is based on two simple and practical criteria: theoretical maximal heart rate for age (MHR) and serum lactic acid levels 3 minutes after exercise. Usually only MHR is used, 85% of MHR being the common cut-off point between "interpretable" maximal or "inframaximal" effort and useless effort. Our study was based on 1 000 exercise stress tests performed over a two year period with the same protocol and equipment. Initially, we determined our values of MHR and serum lactic acid in undoubted maximal effort stress tests, as shown by a levelling out of the heart rate during the last load increments, the last stage of exercise being sustained for at least 1.5 minute. The application of both criteria to all the investigations showed significant differences in the evaluation of the exercise obtained when the maximal measured heart rate was between 85 and 95% of MHR. This was also true, to a lesser extent, in patients over 60 years of age or under 30 years of age with maximal measured heart rate of 85% or less than MHR. A discussion of the theoretical basis of the two criteria helps explain this divergence, attributing it to the inaccuracy and unreliability of the MHR. The only obstacle to the use of serum lactate as the preferential indicator of maximal effort is the need for laboratory facilities and the delay in obtaining the result.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of branched-chain amino acids supplementation on physiological and psychological performance during an offshore sailing race.

The aim of the present study was to investigate the effect of protein diets, rich in branched chain amino acids (BCAA) on perceived exertion, mental and physical performance during an offshore sailing race that lasted 32 h. Twelve sailors were randomly allocated into one of two groups [Control (CON) and BCAA: n = 6/group]. The BCAA group consumed a standard diet of 11.2 MJ day(-1) (58% carbohydrate, 30% fat, 12% Protein) along with a high-protein supplement of 1.7 MJ day(-1) (40% carbohydrate, 35% protein, 25% fat) and 1.7 MJ day(-1) composed of 50% valine, 35% leucine, and 15% isoleucine. CON was given a standard diet of 14.5 MJ day(-1) (58% carbohydrate, 30% fat and 12% protein). During the race, heart rate was monitored. Subjects self-evaluated their feeling of fatigue every 3 h, and 12 samples of saliva from each subject were collected to perform cortisol assays. Before and after the race a vertical jump and a handgrip test were performed, and mental performance was evaluated with a standardized battery of tests. A significant increase in the feeling of fatigue was noted on the second day (D2) of race in both groups; the increase was higher in CON (P < 0.05). For both groups, salivary cortisol concentration followed a nycthemeral rhythm, with an alteration during the race as evidenced by high midnight cortisol levels between D1 and D2, and significantly decreased cortisol levels observed on D2 (P < 0.05). There was no change in physical performance at the end of the race in both groups. As a significant decrease (P < 0.05) in short-term memory performance was observed only in the CON group. These data indicate that an offshore sailing race enhances the feeling of fatigue, and decreases short-term memory performance. These detrimental consequences are reduced by a high-protein diet with BCAA.

Heart rate variability, training variation and performance in elite swimmers.

The aim of the present study was to investigate the relationships between heart rate variability (HRV) changes and both training variations and performances in elite swimmers. A secondary purpose was to measure catecholamine urinary excretion in elite swimmers to validate the HRV indices of sympathetic activity during training. Thirteen swimmers (4 females and 9 males) were tested before and after 4 weeks of intense training (IT) and 3 weeks of reduced training (RT). At the end of each period, the swimmers participated in an official competition of their best event. Individual performances were expressed as percentage of the previous season's best performance. Spectral analysis was used to investigate RR interval variability. HRV indices failed to show any significant changes between the study periods (p>0.05). Pre-IT HF was correlated with performance (r=0.45; p=0.05) and HFnu (r=0.59; p<0.05) during RT. On the other hand, once RT was completed, HFnu was correlated positively to performance (r=0.81; p<0.01) and negatively to fatigue (r=- 0.63; p<0.03). Conversely, the indices of sympathetic activity, i.e., LFnu and LF/HF ratio were inversely related to performance (both r=- 0.81; p<0.01); total fatigue score was correlated to the changes in HFnu (r=- 0.63; p<0.03) and in the LF/HF ratio (r=0.58; p<0.05). Changes in the adrenaline/noradrenaline ratio over the follow-up period were related to the changes in the LF/HF ratio (r=0.45; p<0.03). In highly trained swimmers coping well with a training program, including 4 weeks of IT followed by 3 weeks of RT, HRV indices were unaltered. On the other hand, after the 3 weeks of RT, HFnu was positively related to performance and inversely related to the fatigue score. Thus, elevated initial HF levels could be important in the parasympathetic activity increases during taper and, hence, in swimming performance improvement.