Neuromuscular and inflammatory responses to handball small-sided games: the effects of physical contact.

The aim of this study was to investigate the influence of physical contact on neuromuscular impairments and inflammatory response during handball small-sided games. Using a counterbalanced design, 12 elite male junior handball players were divided into two groups: contact (C-SSG) and no-contact (NC-SSG), performing both contact and no-contact small-sided games, in reverse order on two training sessions separated by 5 days. The methodology and rules were identical for the two SSG regimens, with the only difference being the inclusion or prohibition of upper body use for physical contacts. Upper and lower body neuromuscular performances and blood concentrations of inflammatory cytokine IL-6 were assessed before and immediately after the games. During small-sided games, video analysis was used to establish the physical contact counts. Significant differences were found in most upper and lower limbs muscles kinetic variables and in the physical contact events (all P < 0.001) following the two training regimens. There was an increase in IL-6 after C-SSG and no changes following NC-SSG (P < 0.05 and P = 0.12, respectively). Moreover, a strong correlation was found between the number of physical contacts and IL-6 responses (r = 0.971, P < 0.001) in C-SSG. This study indicates that an inflammatory response and large upper and lower body neuromuscular impairments result from physical contact in elite handball players. These outcomes outline the specific physiological profile of C-SSG that, in turn, might be used by practitioners and coaches as a practical approach to strategically select exercises in athlete's overall training program.

Genetic score of power-speed and endurance track and field athletes.

Athletic excelling capability in a specific sport results from the combined influence of hundreds of genetic polymorphisms. The aim of the current study was to characterize athletes' polygenetic scores. We developed two polygenetic scores: (a) Power Genetic Distance Score based on two polymorphisms (PGDS2; ACE(I/D), ACTN3(C/T)) or five polymorphisms (PGDS5; ACTN3(C/T), ACE(I/D), IL6(-174G/C), NOS3(T/C), AGT(MET235THR)); and (b) Endurance Genetic Distance Score based on two polymorphisms (EGDS2; ACEI / D , ACTN3C / T ) or five polymorphisms (EGDS5; PPARGC1(AGly482Ser), PPAR(Aintron7G/C), PPARD(T294C), NRF2(A/C), HIF(C/T)). Eighty-two power-speed athletes, 87 endurance athletes, and 119 nonathletic controls participated in the study. Genomic DNA was extracted from peripheral blood. Power-speed athletes' mean PGDS2 (46.1) and PGDS5 (29.4) were significantly higher compared with their mean EGDS2 (36.4) and EGDS5 (23.1; P < 0.05, P < 0.01, respectively); and compared with controls' mean PGDS2 (36.6) and PGDS5 (24.2; P < 0.05, P < 0.05, respectively). Endurance athletes' mean EGDS2 (60.3) and EGDS5 (35.3) were significantly higher compared with their mean PGDS2 (26.9) and PGDS5 (21.8; P < 0.001, P < 0.001, respectively); and compared with controls' mean EGDS2 (51.2) and EGDS5 (26.1; P < 0.05, P < 0.001, respectively). We conclude that polygenetic scores can differentiate power-speed from endurance athletes. Whether these scores may be used to identify elite power-speed or endurance athletes' needs to be addressed in future studies.

Differences in MCT1 A1470T polymorphism prevalence between runners and swimmers.

Skeletal muscle is the major producer and user of lactate in the body. Therefore, transport of lactate across cells' membrane is of considerable importance. Lactate transport is mediated by proton-linked monocarboxylate transporter (MCT1). The A1470T polymorphism (rs1049434) in MCT1 gene influences lactate transport, with T allele associated with reduction of lactate transport rate and elevation in blood lactate levels. The aim of the current study was to compare allelic and genotype frequencies of MCT1 A1470T polymorphism among Israeli track-and-field athletes, swimmers, and non-athletes. Genomic DNA was extracted from 173 track-and-field athletes (age 17-50), 80 swimmers (age 16-49), and 128 non-athletes (age 19-29). Track-and-field athletes were assigned to three subgroups: long-distance runners, middle-distance runners, and power event athletes. Swimmers were assigned to two subgroups: long-distance swimmers and short-distance swimmers. Genotyping was performed using polymerase chain reaction. T-allele frequency was significantly higher among long-distance swimmers (45%) compared with long- and middle-distance runners (27% and 30%, respectively; P < 0.01). In addition, T-allele frequency was significantly higher among short-distance swimmers (40%) compared with power event athletes (25%, P < 0.01). Overall, T-allele frequency was significantly higher among swimmers (42%) compared with runners (27%, P < 0.001). More research is needed to clarify whether this polymorphism displays advantage for swimming performance.

Effects of a very short-term preseason training procedure on the fitness of soccer players.

AIM: The aim of the study was to examine the effect of a very short-term training program on the immediate and late changes in the fitness level of young soccer players during the pre-season period. METHODS: Twenty-four young (17-18 years) soccer players were randomly assigned to either an interval (9 to 5 X 1000 m) or continuous (9000 to 5000 m) training group, matched for total running distance. While the number of intervals or total distance was reduced every day, speed was increased in each session throughout the five days of both training programs. Each group performed 20 m shuttle run, 10 m sprint, 5 X 10 m run, 250 m run and vertical jump test, before (pre), immediately after (post) and 10 days after (late) completion of five successive training days during the preseason period for the upcoming soccer season. RESULTS: There was a significant increase in aerobic capacity both immediately post-training and in the late test, in both training groups. We found a significantly greater reduced performance in the 250 m run immediately following training in the interval compared to the continuous training group. In addition, there was a decrease in vertical jump that was significantly greater in the interval compared to the continuous training group, both immediately post-training and in the late test. CONCLUSION: Very short interval or continuous preseason training programs induce significant improvement in aerobic fitness but lead to stagnation or deterioration in anaerobic performance. Considering the opposing effects of both training modes (positive on the aerobic power but negative on the anaerobic performance), coaches should make their choices based on the relevant conditions at hand.

Genetic aspects of exercise and rhabdomyolysis.

Rhabdomyolysis is a syndrome characterized by muscle necrosis and the release of intracellular muscle constituents into the circulation. Consequently, the circulatory levels of intracellular molecular components, such as creatine kinase, are commonly used to evaluate the severity of muscle damage. Nevertheless, there is a wide inter-individual variability in the phenotypic expression of muscle damage, which cannot be predicted by the age, race, body composition, and fitness level of each subject. This suggests that apart from environmental factors, genetic factors might also contribute to the development and progression of exercise-induced muscle damage. Recently, several gene-specific single nucleotide polymorphisms (SNPs) were found to be associated with severe exercise-induced muscle damage. The present manuscript reviews the pathophysiology of exertional muscle damage, emphasizing the influence of gene polymorphisms on its inter-individual severity. This knowledge may be useful for pediatricians for identifying individuals more susceptible to severe exertional muscle damage and related life-threatening comorbidities.

Is there an interaction between BDKRB2 -9/+9 and GNB3 C825T polymorphisms and elite athletic performance?

The -9 deletion allele in the BDKRB2 -9/+9 polymorphism was associated previously with improved endurance performance. We compared the frequency distribution of the BDKRB2 -9/+9 (rs5810761) polymorphism between athletes (n=155) of sports with different demands (endurance runners; n=74 vs sprinters; n=81) as well as between athletes of different competitive levels (elite level; n=46 vs national level; n=109). These results were compared with those of 240 non-athletic healthy individuals. We also tested the influence of the interaction between the BDKRB2 -9/+9 and the GNB3 C825T (rs5443) genotypes in relation to endurance performance. Genotype distribution and allele frequencies were found to be similar in the endurance athlete, sprinter, and control groups (P=0.83 for genotype distribution and P=0.9 for allele frequencies). Similarly, no statistical differences were found between the subgroups of elite-level endurance athletes and national-level endurance athletes, or between elite-level and national-level sprinters (P>0.09 for all comparisons). There was no interaction between BDKRB2 -9/+9 and GNB3 C825T polymorphisms in relation to endurance performance (P=0.16 for interaction effect). In conclusion, the BDKRB2 +9/-9 polymorphism is not associated with endurance performance, at least among Israeli athletes, and the GNB3TT+BDKRB2 -9/-9 "optimal genotype" is not associated with endurance performance.

GNB3 C825T Polymorphism and elite athletic status: A replication study with two ethnic groups.

We aimed to replicate the original findings by Eynon et al. showing an association between the T allele of the GNB3 C825T polymorphism and elite endurance athletic status, in larger cohorts and in other ethnicities. We compared allelic and genotypic frequencies of the GNB3 C825T polymorphism among non-athletic controls (N=340), elite endurance athletes (N=174), and power athletes (N=134). The population sample included participants from 2 different ethnic/geographic backgrounds (Israel and Spain). We observed no significant differences in genotypic and allelic frequencies between countries or groups (all P>0.1). The odds ratio (OR) of being an endurance athlete if the subject had a T allele was 0.841 (95%CI: 0.638-1.110) compared to the control group and 1.047 (95% CI: 0.751-1.461) compared to the power group. Our findings support the need to corroborate genotype:phenotype associations in the field of sports genetics with the largest possible population samples, including populations of different ethnic backgrounds.

Do PPARGC1A and PPARalpha polymorphisms influence sprint or endurance phenotypes?

Functional Gly482Ser (rs8192678) and G/C (rs4253778) polymorphisms in the Peroxisome proliferator-activated receptor gamma coactivator1 (PPARGC1A) and Peroxisome proliferator-activated receptor alpha (PPARalpha) genes, respectively, have been associated with mRNA and protein activity. The aim of this study was to determine their frequency distribution among 155 Israeli athletes (endurance athletes and sprinters) and 240 healthy controls. Results showed that there was a significant difference in PPARGC1A Ser482Gly polymorphism genotype frequencies between endurance athletes and sprinters (P=0.005) as well as between endurance athletes and controls (P=0.0003). However, the sprinters' genotype and allele frequencies were similar to that of the control group. A significantly lower proportion of PPARGC1A Ser482 allele (0.25) was noted for the endurance athletes compared with controls (0.43, P=0.0001). Endurance athletes showed a trend of a higher yet a not significant proportion of the PPARalpha GG genotype compared with sprinters (P=0.051). As we compared between the subgroups of top-level endurance athletes and top-level sprinters, as well as between those of top-level and national-level endurance athletes, we reached more prominent results. In conclusion, our data indicate that a lower frequency of the Ser482 allele and possibly a higher frequency of the GG genotype are associated with increased endurance performance ability.

CK-MM gene polymorphism does not influence the blood CK activity levels after exhaustive eccentric exercise.

Gene variants, such as creatine kinase (CK) polymorphisms, have been suggested to explain the inter-individual blood CK response to eccentric exercise. However, since this association is still doubtful, the purpose of this study was to analyse the relationship between the magnitudes of the CK response to exercise with the occurrence of muscle CK-MM NcoI polymorphism in young healthy subjects. Blood CK activity was assessed in 70 subjects immediately before and 3, 24, 48, 72, 96, 120, 168 h after strenuous eccentric exercise. Based on the amount of CK release by each subject, the sample was distributed in quartiles and the genotype and allele frequency distribution was compared among quartiles. Despite the inter-individual variability of CK response observed between subjects, there were no differences in genotype and allele frequencies among quartiles. The results allowed us to conclude that CK response after exhaustive eccentric exercise is not associated with CK-MM Ncol polymorphism.

Effect of different sprint training regimes on the oxygen delivery-extraction in elite sprinters.

AIM: The effects of sprint training regimes of varying distance schedules on the oxygen delivery-extraction relationship were investigated in 15 young (22+/-1 years) healthy males national-level sprinters. METHODS: During one session subjects performed four sprints, in a schedule of increasing distance order (100, 200, 300 and 400 m), and during the other session, in a schedule of decreasing distance order (400, 300, 200, and 100 m). All sprint bouts were performed on a treadmill at a speed of 22 km/h-1, which corresponds to 85% of subjects' maximal speeds. The order of the running sequences during sessions was balanced over subjects. RESULTS: During both sprint schedules, all variables except for oxygen extraction in the incremented training regime, increased significantly from rest to exercise. Training regimes were not different with regard to cardiac output and absolute oxygen uptake. However, the decreasing compared to the increasing scheme was characterized by significantly (P<0.05) higher mean values of heart rate (194.5+/-4.1 185.2+/-5.7 beats/min-1, respectively), oxygen extraction (54.3+/-3.8 and 47.1+/-3.4 mL/L-1, respectively) and lactate (10.6+/-0.5 and 9.2+/-0.7 mmol/L-1, respectively), while stroke volume was significantly (P<0.05) lower (100.4+/-4.5 and 109.7+/-4.4 mL, respectively). CONCLUSION: The present study indicates that in sprinters performing a similar distance at the same speed, but under different training regimes interplay exists between oxygen delivery and extraction, suggesting a link between the type of training scheme and physiological cardiovascular and skeletal muscle metabolic adaptations. This may explain the absence of differences between the conditions in absolute oxygen uptake and peak power output.

ACTN3 R577X polymorphism and Israeli top-level athletes.

A common genetic variation in the alpha-actinin-3 ( ACTN3) gene causes a replacement of an arginine (R) with a premature stop codon (X) at amino-acid 577 (rs1815739). While the R allele has been found to be associated with power-oriented performance, the XX genotype may be linked with endurance ability. To test this hypothesis, we studied the distribution of ACTN3 genotypes in 155 Israeli athletes (age=35.9+12.2 years) classified by sport (endurance runners and sprinters) and in 240 sedentary individuals. The sprinters' allele frequencies (AF: R/X=0.7/0.3) and 577RR genotype distribution percentage (GD: RR=52%) differed markedly from those of the endurance athletes (AF: R/X=0.53/0.47, p=0.000007; GD: RR=18%, p=0.00009) and the control group (AF: R/X=0.55/0.45, p=0.0002; GD: RR=27.3%, p=0.000003). A comparison between the top-level and national-level sprinters revealed that the R allele occurs more often in the top-level sprinters. A significantly higher proportion of the XX genotype was observed in endurance athletes (34%) compared with controls (18%, p=0.02) and sprinters (13%, p=0.002). However, top-level and national level endurance athletes had similar allele and genotype frequencies. We conclude that the ACTN3 R allele is associated with top-level sprint performance and the X allele and XX genotypes may not be critical but rather additive to endurance performance.

Is there an ACE ID - ACTN3 R577X polymorphisms interaction that influences sprint performance?

Functional R577X (rs.1815739) and ID (rs.5186) polymorphisms in the alpha-actinin-3 ( ACTN3) and the angiotensin converting enzyme (ACE) genes, respectively, have been associated with sprint performance. The aim of this study was to determine their effect on sprint performance among 81 Israeli sprinters and 240 healthy controls. Results revealed that the ACE II genotype+ ACTN3 R allele (P=0.003 for sprinters vs. controls), and the ACTN3 RR genotype +ACE I allele (P=0.001 for sprinters vs. controls) might be the genotype for sprinters. In the whole cohort the probability of ACTN3 RR genotype+ ACE I allele being a sprinter (odds ratio 2.67, 95% confidence interval 1.45-4.93) and of ACE II genotype+ ACTN3 R allele being a sprinter (odds ratio 3.57, 95% confidence interval 1.78-7.15) was significantly higher than that in the controls. In conclusion, the above data suggest that ACE ID/ ACTN3 R577X genotype combination is associated with sprint ability. However, ACE ID/ ACTN3 R577X genotype combination is not related to the level of performance.

Effects of different sprint cycling bouts on left ventricular function in top cyclists.

AIM: The study investigated lactic acid and left ventricular function in response to two different sprint cycling schedules varying in their time schedule, in 15 healthy national level cyclists (23+/-1 years). METHODS: During one testing session subjects performed four strenuous bouts in a schedule of increasing time order: 1, 2, 3 and 4 min. In the other session, they performed a decreasing order: 4, 3, 2 and 1 min. Resting time between bouts in the increasing schedule were 2, 3, and 4 min, respectively. Resting times for the decreasing schedules were 4, 3 and 2 min, respectively. Exercise bouts were performed on an electrical cycle ergometer at 85% of each subject's maximal speed velocity. RESULTS: In both sprint cycling schemes, mean end-systolic volume and mean end-diastolic volume decreased significantly (P < 0.05) with bout's time. However, there was a significant interaction effect regarding schedule order and lactate accumulation. In the incremented scheme, lactate accumulated gradually during the session, while a high level of lactate was maintained throughout the decremented scheme (from 3.8+/-0.7 to 11.8+/-1.8 and from 9.5+/-1.5 to 10.8+/-1.9 mmol.L-1, respectively). Furthermore, analysis of cardiac function during the two schemes demonstrates different physiological responses. The decreasing scheme was characterized by a higher mean heart rate, a lower mean stroke volume and a lower mean end-diastolic volume (P < 0.05) indicating that during the two schemes, the functional mechanisms underlying cardiac response, are different. CONCLUSION: Our data suggest that in the face of high levels of lactic acid, during the decreasing scheme, venous return may be impeded, most likely due to reduced left ventricular filling time and inadequate vasodilatation of the arteries during the early phase of cycling bout. In addition, it suggests that the decreasing scheme may yield a better anaerobic and cardiovascular training method.

Physiological characteristics of female 100 metre sprinters of different performance levels.

The purpose of this study was to compare physiological characteristics of three different levels of 100 m female sprinters. The 30 subjects in this study (20 female track athletes and 10 recreationally trained females) were assigned, according to their 100 m running time, to one of three different groups: "Fast" (11.8 +/- 0.1 sec), "Average" (12.7 +/- 0.1) and "Slow" (14.2 +/- 0.1 sec). All subjects were tested for performance in the Wingate Anaerobic Test (WAnT), strength (squat exercise), fat % (hydrostatic weighing), reaction time, flexibility (sit-and-reach test), aerobic power (peak VO2) and running skill. The data was analyzed by one-way Analysis of Variance (ANOVA) with post-hoc Tukey test, which was performed on each variable to find differences between the groups. The ANOVA indicated significant differences among all three groups for performance in the Wingate Anaerobic Test and relative strength. Significant differences in fat % and running skill were found between the fast and the slow groups and between the average and the slow groups. However, no significant difference in fat % and running skill existed between the fast and the average groups. The differences in reaction time were significant only between the fast and the average groups. No two groups were significantly different from each other for flexibility and peak VO2. Pearson correlation coefficients (r) were calculated to determine the relationships between the 100m running time and each of the variables tested. Significant and negative correlations were found between the 100m running time and skill, relative strength, and performance in the WAnT. Significant and positive correlations were found between running time and fat %. No significant correlations were found between running time and peak VO2 reaction time and flexibility. Stepwise regression analysis indicated that the combination of performance in the WAnT and strength provided the most efficient (R = 0.92) prediction of 100 m run times. This study demonstrated that the main difference among female sprinters of different performance levels lies in their ability to produce muscular power, strength and running technique. Other physiological components, such as flexibility, peak VO2, and reaction time do not differ among female sprinters of different performance levels as represented in the tested groups.

Increased prevalence of MnSOD genetic polymorphism in endurance and power athletes.

The purpose of the current study was to determine the frequency distribution of manganese superoxide dismutase (MnSOD) Val-9Ala polymorphism (rs1799725) among 195 trained endurance and power athletes and 240 healthy controls. Genomic DNA was extracted using a standard protocol. Genotyping of the MnSOD Val-9Ala polymorphism was performed using polymerase chain reaction (PCR). Results showed a higher proportion of the Val/Ala and Ala/Ala genotype, and a lower proportion of Val/Val genotype, in the athletes group compared with that of the controls. The Ala allele frequency was significantly higher (p < 0.001) in the athletes group (46%) compared with that in the control (29%). Interestingly, there was no difference between the endurance and power athletes. In addition, the frequency of Ala/Ala genotype was significantly higher (p < 0.05) among top (international and Olympic-level) athletes (29%) compared with that among national-level endurance and power athletes (17%). We conclude that 1) the Ala allele is more frequent in athletes than in controls; and 2) the higher frequency of the Ala allele was noted in both endurance and power athletes compared with that in controls, suggesting that the positive association between the Ala allele and athletic performance may be related to ROS-related angiogenesis, mitochondrial biosynthesis, and muscle hypertrophy, and not to MnSOD aerobic properties.

The effect of music during warm-up on consecutive anaerobic performance in elite adolescent volleyball players.

Music is believed to improve athletic performance. The aim of the present study was to determine the effect of arousing music during warm-up on anaerobic performance in elite national level adolescent volleyball players. Twenty-four players (12 males and 12 females) performed the Wingate Anaerobic Test following a 10-minute warm-up with and without music (two separate occasions, random order). During warm-up with music, mean heart rate was significantly higher. Following the warm-up with music, peak anaerobic power was significantly higher in all volleyball players (10.7 +/- 0.3 vs. 11.1 +/- 0.3 Watts/kg, p < 0.05, without and with music, respectively). Gender did not influence the effect of music on peak anaerobic power. Music had no significant effect on mean anaerobic output or fatigue index in both genders. Music affects warm-up and may have a transient beneficial effect on anaerobic performance.

Estimation of %VO2 reserve from heart rate during arm exercise and running.

The purpose of the present investigation was to examine the relationship between the percent heart rate reserve (%HRR) in arm exercise and the corresponding percent oxygen uptake (VO2) reserve, and to compare this relationship to that occurring in running. Fourteen male physical education students took part in the study. Each subject performed a maximal running exercise test and a maximal arm cycling test. The subjects also performed three submaximal exercise bouts (in both exercise modes) at 30%, 60% and 80% of their HRR. The subjects were monitored for their heart rate (HR) at rest, maximal HR (HRmax), HR at submaximal work loads. maximal VO2 (VO2max), VO2 at rest and VO2 at submaximal loads. For each subject, load and exercise mode, %HRR and %VO2 reserve were calculated (from HRmax and VO2max as measured during running and arm cycling) and the relationship between the two was evaluated. The main finding of the present investigation is that the prediction of %VO2 reserve in arm cycling from %HRR is grossly overestimated when calculated from HRmax and VO2max measured during running. The prediction is better but still overestimated when calculated from HRmax and VO2max measured during arm cycling. The findings indicate a better prediction of %VO2 reserve from %HRR for running than for arm exercise. These findings should be taken into consideration when prescribing the target HR for arm training.

Perceived speech difficulty during exercise and its relation to exercise intensity and physiological responses.

The aim of this study was to establish how ratings of perceived speech production difficulty (PSPD) during exercise of varying intensities are correlated with various physiological responses, in order to determine whether the PSPD is suitable for prescribing exercise training intensity. An incremental running test was performed to establish the subjects' maximal oxygen consumption (VO(2max)) and ventilatory anaerobic threshold (VAT). During the test, the subjects were asked to read a written text. The subjects graded their PSPD at each stage of the test using a 13-level PSPD scale. Throughout the test, various cardiopulmonary parameters were measured breath-by-breath. Regressions of VO(2), heart rate (HR), and pulmonary ventilation (V(E)), all as percentages of their respective measured maximal values, plotted as a function of PSPD showed that the overall associations among those variables are strong and statistically significant ( P<0.05). However, the individual variability within each relative VO(2), V(E) or HR was found to be rather large. The subjects' distribution in relation to their PSPD at the VAT scattered widely across the PSPD scale. These results indicate that estimating exercise intensity by measuring speech difficulty is not valid. Thus it may be assumed that the "talk test", in its present non-standardized form, is a questionable substitute for the anaerobic threshold, HR, or for any other objective physiological measure for prescribing individual training exercise intensity.