Genome-wide association study identifying variants related to performance and injury in high-performance athletes.

A growing body of evidence exists supporting the role that genetic variation plays in athletic performance and injury. This study sought to identify genetic variants associated with performance and lower limb musculoskeletal injury in a high-level athletic cohort. A total of 126 Estonian National Team members (Olympic athletes and participants of International Championships) (104 males, 82.5%) underwent a genome-wide association analysis between 2017 and 2018, to identify single-nucleotide polymorphisms (SNPs) associated with performance and/or injury. The athletic cohort was stratified within each sport based on performance and whether they were a medalist (n = 29) or not (n = 97), whether they sustained an injury (n = 47) or not (n = 79), and the type of injury (patella tendinopathy n = 22, Achilles tendinopathy n = 17, hamstring injury n = 3, anterior cruciate ligament rupture n = 6). Three SNPs demonstrated strong genome-wide association with athletic performance (podium/medalist versus not), including DSG1 (rs10502567, OR 14.3) and DSG4 (rs73410248, OR 17.4), while 76 SNPs demonstrated suggestive significance. Overall, 37 SNPs gave genome-wide suggestive association with any type of injury, including PAPPA2 (rs11580456, OR 13.8) and MAS1 (rs220735, rs170219, OR 3.1) which demonstrated positive signal with multiple SNPs. Several genes demonstrated positive association for the specific injury types, including COL22A1 (rs3924862) and PLXNA2 (rs11799530), as well as PAPPA2 (rs11580456), DOK5 (rs73142922), GNG12 (rs28435277), and DAP (rs267959, rs2930047, rs1080440, rs267939). The current study identified genetic variants associated with high-level athletic performance and musculoskeletal injury. Further work is required to permit integration of this and future knowledge into individualized training practices, as well as injury mitigation and rehabilitation programs.

Serum Osteocalcin, Sclerostin and Lipocalin-2 Levels in Adolescent Boys with Obesity over a 12-Week Sprint Interval Training.

The aim of the study was to examine the effects of supervised cycling sprint interval training (SIT) on serum osteocalcin, lipocalin-2 and sclerostin levels, and bone mineral characteristics among obese adolescent boys. Untrained obese adolescent boys aged 13.4 ± 0.3 were assigned to either a 12-week SIT group (3 sessions/week), or a non-exercising control group who continued with their habitual everyday life. Serum osteocalcin, lipocalin-2 and sclerostin concentrations, and bone mineral values were assessed before and after intervention. After 12-week intervention, where 14 boys in both groups ended the study, there were no significant differences in serum osteokine levels between the groups after 12 weeks, while whole body bone mineral content and lower limb bone mineral density increased in the SIT group (p < 0.05). Change in body mass index was negatively correlated with the change in osteocalcin (r = -0.57; p = 0.034), and positively correlated with the change in lipocalin-2 levels (r = 0.57; p = 0.035) in the SIT group. Supervised 12-week SIT intervention improved bone mineral characteristics, but did not change osteocalcin, lipocalin-2 or sclerostin levels in adolescent boys with obesity.

Vitamin D Supplementation Has No Impact on Cardiorespiratory Fitness, but Improves Inflammatory Status in Vitamin D Deficient Young Men Engaged in Resistance Training.

Data on the effect of vitamin D (Vit-D) supplementation on cardiorespiratory fitness (VO2max) are conflicting. A possible source of discrepancies in the literature is the heterogeneity in baseline Vit-D status among participants in previous studies. The main objectives of the present study were to assess the impact of Vit-D supplementation on VO2max and inflammatory status in Vit-D deficient young healthy men. Participants (n = 39, baseline serum Vit-D level < 50 nmol/L) were quasi-randomly assigned to one of the two groups, which, in a double-blind manner, supplemented their diet daily with either Vit-D (8000 IU; VD) or placebo (PLC) and concomitantly performed a 12-week supervised resistance training program. During the 12-week intervention, serum Vit-D concentrations increased 3.9-fold (p < 0.001) in the VD group while no changes occurred in the PLC group. Baseline VO2max did not differ in the two groups and remained unchanged during the intervention. Serum interleukin-10/tumour necrosis factor alpha ratio increased significantly (30%, p = 0.007; effect size 0.399) in VD but not in PLC group. In conclusion, 12-week Vit-D supplementation increases serum 25(OH)D levels and improves inflammatory status, but has no impact on VO2max in Vit-D deficient young men engaged in resistance training.

Effect of Sprint Interval Training on Cardiometabolic Biomarkers and Adipokine Levels in Adolescent Boys with Obesity.

This study investigated the effect of supervised sprint interval training (SIT) on different cardiometabolic risk factors and adipokines in adolescent boys with obesity. Thirty-seven boys were allocated to either a SIT group (13.1 ± 0.3 years; body mass index [BMI]: 30.3 ± 0.9 kg·m-2) or a control group (CONT) (13.7 ± 0.4 years; BMI: 32.6 ± 1.6 kg·m-2). The SIT group performed 4-6 × 30 s all-out cycling sprints, interspersed with 4 min rest, for 3 sessions/week, during a 12-week period, while the non-exercising CONT group maintained a habitual lifestyle. Anthropometric measurements, triglycerides, fasting insulin and glucose, total cholesterol (TC), high- (HDLc) and low-density (LDLc) cholesterol, leptin and adiponectin in blood, cardiorespiratory fitness (CRF), and a metabolic syndrome severity risk score (MSSS) were calculated before and after the 12-week period. Compared to baseline values, a significant reduction in MSSS was seen in the SIT group after intervention. LDLc showed favorable changes in SIT compared to CONT (-0.06 ± 0.1 vs. 0.19 ± 0.01 mmol·L-1; p = 0.025). Additionally, CRF increased in the SIT group compared to the CONT group (5.2 ± 1.1 vs. -2.1 ± 1.1 mL·min-1·kg-1, p < 0.001). Moreover, a 12-week all-out SIT training effectively improves cardiometabolic health in adolescent boys with obesity.

Effect of supervised sprint interval training on cardiorespiratory fitness and body composition in adolescent boys with obesity.

This study examined the effect of a supervised 12-week sprint interval training (SIT) on cardiorespiratory fitness (CRF) and body composition in adolescent boys with obesity. Twenty-eight adolescents with obesity were allocated to either an intervention group (SIT) (13.1 ± 0.3 yrs; body mass index [BMI]: 30.3 ± 0.9 kg.m-2) or a control group (CONT) (13.7 ± 0.4 yrs; BMI: 32.6 ± 1.6 kg.m-2). The SIT group performed 4-6 × 30s "all-out" cycling bouts, interspersed with 4 min of recovery 3 days a week for 12 weeks. CRF was measured by direct peak oxygen consumption (VO2peak) defined as VO2peak per kg of body mass (mL.min-1kg-1) or by VO2peak per kg of lean body mass (mL.min-1LBM-1) and body composition was assessed by dual-energy X-ray absorptiometry. SIT intervention led to a significant and large between-group difference in VO2peak (p = 0.004; η2 = 0.29). Although SIT group had a significant reduction in body fat percentage (BF%) (from 41.1 ± 1.3% to 39.2 ± 1.5%; p = 0.006), there were no between-group differences in the change of the pre- and post-measures in BF% (p = 0.067). In conclusion, 12-week SIT is effective in increasing CRF and decreasing BF% in adolescent boys with obesity.

Impact of sodium citrate ingestion during recovery after strenuous exercise in the heat on heart rate variability: A randomized, crossover study.

Changes in hydration status influence plasma volume (PV) which is associated with post-exercise parasympathetic reactivation. The present study hypothesized that, after dehydrating cycling exercise in the heat (DE), stimulation of PV expansion with sodium citrate (CIT) supplementation would promote heart rate variability (HRV) recovery in endurance-trained men. Twelve participants lost 4% of body mass during DE. During subsequent 16-h recovery, participants consumed water ad libitum (CIT =5.5-L, PLC =5.1-L) and ate prescribed food supplemented with CIT or placebo in a randomized, double-blind, crossover manner. Relative changes in PV were assessed across DE and 16-h recovery. HRV was analyzed before and 16 h after DE in three conditions for altogether four 5-min periods: supine in a thermoneutral environment, supine in the heat (32°C, 46% relative humidity; 2 periods), and standing in the heat. A larger expansion of PV across 16-h recovery occurred in CIT compared to placebo trial (p < 0.0001). However, no between-trial differences appeared in HRV parameters (lnRMSSD, lnSDNN, lnLF/HF) in any 5-min period analyzed before or 16 h after DE (in all cases p > 0.05). Increases in HR (p < 0.001) and lnLF/HF (p = 0.005) and decreases in lnRMSSD (p < 0.001) and lnSDNN (p < 0.001) occurred following DE in both trials. Larger PV expansion induced by CIT supplementation after DE does not improve recovery of HRV at rest and has no influence on HRV responsiveness in endurance-trained men.

Vitamin D supplementation does not enhance resistance training-induced gains in muscle strength and lean body mass in vitamin D deficient young men.

PURPOSE: Vitamin D (Vit-D) supplementation has been shown to increased muscle strength in young adults. It remains unclear if Vit-D supplementation enhances the efficacy of resistance training (RT). This study tested the hypothesis that Vit-D supplementation would enhance the RT-induced increases in muscle strength and lean body mass (LBM) in Vit-D deficient young men. METHODS: Thirty-nine men (baseline serum 25(OH)D < 50 nmol L‒1) were quasi-randomly assigned to one of the two groups that performed a 12-week supervised RT program concomitant with either Vit-D (8000 IU daily; VD) or placebo (PLC) supplementation. RESULTS: During 12-week RT, energy and nutrient (except Vit-D) intake and training loads did not differ in the two groups. Serum 25(OH)D levels increased from 36.3 ± 9.2 to 142.4 ± 21.9 nmol L‒1 (P < 0.05) in VD group and remained unchanged between 36.3 ± 8.9 and 29.4 ± 6.6 nmol L‒1 (P > 0.05) in PLC group. Muscle strength (1-repetition maximum) increased (P < 0.05) to an equal extent in the two groups in 5 exercises performed on RT equipment, whereas strength gains in chest press and seated row were greater (P < 0.05) in PLC compared to VD group. Total and regional LBM (measured by DXA scan) increased (P < 0.05) equally in the two groups. Android fat mass decreased (P < 0.05) in VD group only. CONCLUSION: Vit-D supplementation does not enhance the efficacy of RT in terms of muscle strength and LBM gains in Vit-D deficient young healthy men.

Effect of Half-Marathon Running on Arterial Stiffness and Blood Biomarkers in High-Level and Recreational Male Athletes.

There is no clear understanding about the effect of intensive physical load on arterial stiffness and related biomarkers. The aim of this study was to evaluate the effect of half-marathon running on arterial stiffness and blood biomarkers during post-competitive recovery period in competitive and recreational male athletes. Eleven high-level long-distance runners (27.1 ± 4.8 yrs) and seven recreational athletes (34.3 ± 6.1 yrs), who participated in a half-marathon run were examined. Blood biomarkers and arterial stiffness (SphygmoCor 7.1) were measured at baseline and at 18 to 22 hours after the competition. There were no statistically significant changes between the groups in augmentation index (AIx, AIx@75) or pulse wave velocities at carotid-femoral segment (cfPWV) during recovery period. Between-group comparison did not reveal significant differences in blood pressure and arterial stiffness values at baseline and during recovery period. The change of cfPWV (difference between cfPWV at baseline and cfPWV during post-competitive recovery period) was significantly dependent on race time and sports level of the athlete (high-level or recreational). A significant increase was found in hsCRP, creatine kinase and LDH activity during the post-race period in both groups. No significant changes were found in oxidative stress markers in the groups after the race except for higher diene conjugates level in recreational athletes in comparison with the high-level group during recovery period. Our study results showed that half-marathon competition did not cause any significant changes in arterial stiffness parameters during the recovery period. However, the change in cfPWV was independently associated with half-marathon race time and the athlete's level of training revealing a mild increase of arterial stiffness in high-level athletes and athletes with a faster race time.

Influence of Sodium Citrate Supplementation after Dehydrating Exercise on Responses of Stress Hormones to Subsequent Endurance Cycling Time-Trial in the Heat.

Background and objectives: In temperate environments, acute orally induced metabolic alkalosis alleviates exercise stress, as reflected in attenuated stress hormone responses to relatively short-duration exercise bouts. However, it is unknown whether the same phenomenon occurs during prolonged exercise in the heat. This study was undertaken with aim to test the hypothesis that ingestion of an alkalizing substance (sodium citrate; CIT) after dehydrating exercise would decrease blood levels of stress hormones during subsequent 40 km cycling time-trial (TT) in the heat. Materials and Methods: Male non-heat-acclimated athletes (n = 20) lost 4% of body mass by exercising in the heat. Then, during a 16 h recovery period prior to TT in a warm environment (32 °C), participants ate the prescribed food and ingested CIT (600 mg·kg-1) or placebo (PLC) in a double-blind, randomized, crossover manner with 7 days between the two trials. Blood aldosterone, cortisol, prolactin and growth hormone concentrations were measured before and after TT. Results: Total work performed during TT was similar in the two trials (p = 0.716). In CIT compared to PLC trial, lower levels of aldosterone occurred before (72%) and after (39%) TT (p ˂ 0.001), and acute response of aldosterone to TT was blunted (29%, p ˂ 0.001). Lower cortisol levels in CIT than in PLC trial occurred before (13%, p = 0.039) and after TT (14%, p = 0.001), but there were no between-trial differences in the acute responses of cortisol, prolactin or growth hormone to TT, or in concentrations of prolactin and growth hormone before or after TT (in all cases p > 0.05). Conclusions: Reduced aldosterone and cortisol levels after TT and blunted acute response of aldosterone to TT indicate that CIT ingestion during recovery after dehydrating exercise may alleviate stress during the next hard endurance cycling bout in the heat.

Oxidative Stress Parameters and Its Associations With Arterial Stiffness in Competitive Powerlifting Athletes After 12-Week Supervised Strength Training.

Jürgenson, J, Serg, M, Kampus, P, Kals, J, Zagura, M, Viru, M, Zilmer, K, Zilmer, M, Eha, J, and Unt, E. Oxidative stress parameters and its associations with arterial stiffness in competitive powerlifting athletes after 12-week supervised strength training. J Strength Cond Res 33(7): 1816-1822, 2019-Available studies have not revealed a clear understanding of the impact of intensive strength training on arterial stiffness and oxidative stress (OxS) parameters, which may have a significant impact on further cardiovascular health of an athlete. The purpose of this study was to evaluate the effect of a 12-week supervised strength training program (SSTP) on oxidative stress indices and its relationship with arterial stiffness in powerlifting athletes. A total of 19 men (28 ± 6 years) exercised for 12 weeks (4 days per week with intensity 60-90% assessed from 1 repetition maximum, 90-120 minutes per session). Oxidative stress parameters and arterial stiffness (SphygmoCor 7.1) were measured before and after SSTP. The study results showed that total peroxide concentration increased and total antioxidant capacity decreased significantly after SSTP. There were no significant changes in carotid-femoral pulse wave velocity (cfPWV) or in the augmentation index. Correlation analysis revealed that the magnitude of the increase of cfPWV was significantly related to the increase of OxS. The current study demonstrated that a 12-week SSTP in powerlifting athletes produced significant changes in OxS indices, which were positively related to increased aortic stiffness. This novel finding may have significant implications about the effect of OxS on cardiovascular health after high-intensity strength training. Furthermore, strength and conditioningcoaches may have to consider the long-term exercise-induced changes in OxS on an individual level, where increased OxS leads to impaired arterial stiffness and cardiovascular health.

Pre-Practice Hydration Status in Soccer (Football) Players in a Cool Environment.

Background and Objectives: Only a few studies have reported the pre-practice hydration status in soccer players (SPs) who train in a cool climate. The primary purpose of this study was to examine the hydration status of male semiprofessional SPs immediately before their regular training session in winter. The secondary purpose was to compare the urinary indices of the hydration status of Estonian and Latvian SPs. Materials and Methods: Pre-training urine samples were collected from 40 Estonian (age 22.1 ± 3.4 years, soccer training experience 13.7 ± 3.9 years) and 41 Latvian (age 20.8 ± 3.4 years, soccer training experience 13.3 ± 3.0 years) SPs and analyzed for urine specific gravity (USG). The average outdoor temperature during the sample collection period (January⁻March) was between -5.1 °C and 0.2 °C (Estonia) and -1.9 °C and -5.0 °C (Latvia). Results: The average pre-training USG of Estonian and Latvian SPs did not differ (P = 0.464). Pooling the data of Estonian and Latvian SPs yielded a mean USG value of 1.021 ± 0.007. Hypohydration (defined as a USG ≥ 1.020) was evident altogether in fifty SPs (61.7%) and one of them had a USG value greater than 1.030. Conclusions: Estonian and Latvian SPs do not differ in respect of USG and the prevalence of pre-training hypohydration is high in this athletic cohort. These findings suggest that SPs as well as their coaches, athletic trainers, and sports physicians should be better educated to recognize the importance of maintaining euhydration during the daily training routine in wintertime and to apply appropriate measures to avoid hypohydration.

Impact of sodium citrate ingestion during recovery after dehydrating exercise on rehydration and subsequent 40-km cycling time-trial performance in the heat.

The purpose of this study was to assess the impact of sodium citrate (CIT) ingestion (600 mg·kg-1) during recovery from dehydrating cycling exercise (DE) on subsequent 40-km cycling performance in a warm environment (32 °C). Twenty male nonheat-acclimated endurance athletes exercised in the heat until 4% body mass (BM) loss occurred. After 16 h recovery with consumption of water ad libitum and prescribed diet (evening meal 20 kcal·kg-1, breakfast 12 kcal·kg-1) supplemented in a double-blind, randomized, crossover manner with CIT or placebo (PLC), they performed 40-km time-trial (TT) on a cycle ergometer in a warm environment. During recovery greater increases in BM and plasma volume (PV) concomitant with greater water intake and retention occurred in the CIT trial compared with the PLC trial (p < 0.0001). During TT there was greater water intake and smaller BM loss in the CIT trial than in the PLC trial (p < 0.05) with no between-trial differences (p > 0.05) in sweat loss, PV decrement, ratings of perceived exertion, or TT time (CIT 68.10 ± 3.28 min, PLC 68.11 ± 2.87 min). At the end of TT blood lactate concentration was higher (7.58 ± 2.44 mmol·L-1 vs 5.58 ± 1.32 mmol·L-1; p = 0.0002) and rectal temperature lower (39.54 ± 0.50 °C vs 39.65 ± 0.52 °C; p = 0.033) in the CIT trial than in the PLC trial. Compared with pre-DE time point, PV had decreased to a lower level in the PLC trial than in the CIT trial (p = 0.0001). In conclusion, CIT enhances rehydration after exercise-induced dehydration but has no impact on subsequent 40-km cycling TT performance in a warm uncompensable environment.

Influence of Rhodiola rosea on the heat acclimation process in young healthy men.

The adaptogen Rhodiola rosea (RR) may mitigate stress responses and have beneficial effects on endurance capacity (EC) and mental performance. Heat acclimation (HA) improves EC in the heat, but the potential impact of RR on the HA process is unknown. Therefore, our intent was to determine if RR has a positive impact on HA. Twenty male subjects (age, 22.5 ± 3.0 years) completed 2 EC tests involving walking (6 km·h-1) until volitional exhaustion in a climate chamber (air temperature, 42 °C; relative humidity, 18%) before (H1) and after (H2) an 8-day HA period. One group (SHR; n = 10) ingested standardised extract SHR-5 of RR (a single daily dose of 432 mg), while a second group (PLC; n = 10) administered a placebo prior to each HA session. Efficacy of HA was evaluated on the basis of changes that occurred from H1 to H2 in the time to exhaustion (TTE), exercise heart rate (HR), core and skin temperatures (Tc, Tsk), stress hormones, ratings of perceived exertion (RPE) and fatigue (RPF), and thermal sensation (TS). HA significantly increased TTE (133.1 ± 44.1 min in H1; 233.4 ± 59.8 min in H2; p < 0.0001) and decreased (p < 0.0001) HR, Tc, Tsk, stress hormones as well as RPE, RPF, and TS. However, the magnitude of all these changes was similar (p > 0.05) in the SHR and PLC groups. These results suggest that the use of RR during HA has no beneficial performance, physiological, or perceptual effects in young healthy males.

The acute effects of passive heat exposure on arterial stiffness, oxidative stress, and inflammation.

BACKGROUND AND OBJECTIVE: The aim of the study was to determine the acute effect of passive heat exposure (PHE) on arterial stiffness, oxidative stress (OxS) and inflammatory parameters. MATERIALS AND METHODS: Subjects were studied in thermoneutral conditions before and after PHE in a climatic chamber. Pulse wave analysis was used for assessment of central hemodynamic and arterial stiffness parameters. Venous blood samples were obtained to measure OxS and inflammatory parameters. RESULTS: Rectal temperature increased after PHE exposure compared to baseline: 37.01°C±0.19°C and 36.4°C±0.31°C, respectively (P<0.001). There was a 17% (P<0.05) decrease in large artery elasticity index (from 24.68±5.53 to 20.42±2.65mL/mmHg*10), which was predicted upon normothermic value (r=-0.878, P<0.01). However, no significant changes were found in others arterial stiffness parameters. A 30% (P<0.05) increase occurred in blood IL-6 concentration (from 0.43±0.15 to 0.56±0.23pg/mL), but OxS parameters remained significantly unchanged. CONCLUSIONS: This study describes for the first time acute PHE effects on arterial stiffness, inflammation and OxS. PHE significantly decreases large artery elasticity index and increases inflammatory IL-6 level. However, further larger investigations are needed for clarifying acute PHE effects on arterial function and biomarkers.

Leisure time physical activity in Estonian population: adherence to physical activity recommendations and relationships with overweight.

BACKGROUND: Sufficient physical activity (PA) is a key element for the prevention of non-communicable diseases. Considering leisure time physical activity (LTPA), the purpose of the survey was to provide descriptive data for LTPA, find the proportion of the study population meeting the recommended WHO PA criteria, and to detect the possible relationship between LTPA and overweight. METHODS: The National Physical Activity Survey was carried out in autumn 2015 in the Estonian population (n = 914) aged 15-69 years. For LTPA assessment, the LTPA domain of IPAQ-L interview version was used. LTPA was analysed in regard to fulfilment of the WHO PA recommendations and in association with BMI. RESULTS: Seventy-three percent of study participants reported any LTPA in the preceding 7 days. 22 % (26 % of men, 20 % of women) met WHO PA recommendations. 50 % of the study participants were considered overweight (48 % of men, 51 % of women) with BMI > 25.0 kg/m(2), whereas 20 % of the total study population was obese (BMI ≥ 30.0 kg/m(2)). Lower adherence to WHO PA recommendations was associated with older age in men, and obesity in both men and women. CONCLUSIONS: A strikingly low proportion of people met WHO PA recommendations and a relatively high proportion of overweight people were detected in the study group. Obesity had significant inverse associations with LTPA.

The Association Analysis between ACE and ACTN3 Genes Polymorphisms and Endurance Capacity in Young Cross-Country Skiers: Longitudinal Study.

Endurance performance depends on the integration of several phenotypic traits influenced by multiple environmental and genetic factors. Objectives of the study were: (1) to examine the genotypic frequencies of the ACE I/D, ACTN3 R577X polymorphisms and endurance performance-related phenotypes, (2) to evaluate the dynamics of endurance performance parameters during a 5-year period in relation to ACE I/D and ACTN3 R577X genotypes in Estonian young skiers. Determination of VO2peak was performed in 58 skiers aged 15-19 years (41 males, 17 females) during a 5-year period. The control group consisted of 322 healthy non-athletic subjects (145 males, 177 females). The study groups were genotyped for the ACE I/D and ACTN3 R577X variants. Frequencies of the ACE ID and ACTN3 RR genotypes were significantly higher (p = 0.047 and p = 0.003, respectively) and the RX genotype was lower (p = 0.008) in young male skiers compared with controls. A significant relationship was found between change (Δ) of training volume and ΔVO2peak (mL·kg(-1)·min(-1)) (r = 0.475, p = 0.002). No significant main effect was detected between VO2peak (mL·kg(-1)·min(-1)) dynamics (comparison with the previous age group data) and ACE I/D and ACTN3 R577X genotypes interactions (F = 0.571, p = 0.770 and F = 0.650 and p = 0.705, respectively) in all young skiers. Study results indicated a significantly higher frequency of the ACE ID and ACTN3 RR genotypes among Estonian young male skiers compared with the male control group. Significant genotype-related differences in dynamics of VO2peak during a 5-year period were not found. In the future, longitudinal research including different gene variants may contribute to a better understanding of the nature of endurance performance. Key pointsSignificantly higher prevalence of the ACE ID and the ACTN3 RR genotypes were found among Estonian young male skiers compared with the male control group, which may be an advantage for the explosive speed and power capacity in race skiing.A more remarkable trend of increase in VO2peak (mL·kg(-1)·min(-1)) during the 5-year period was observed among male skiers with the ACTN3 XX genotype and among female skiers with the ACE ID genotype.No significant genotype-related associations in the dynamics of VO2peak were found during the 5-year period.

Effects of heat acclimation on changes in oxidative stress and inflammation caused by endurance capacity test in the heat.

BACKGROUND: The aim was to determine the effect of heat acclimation (HA) on oxidative stress (OxS) and inflammation in resting conditions and on the response pattern of these parameters to exhausting endurance exercise. METHODS: Parameters of OxS and inflammation were measured in non-heat-acclimated status (NHAS) and after a 10-day HA program (i.e., in heat-acclimated status; HAS) both at baseline and after an endurance capacity (EC) test in the heat. RESULTS: As a result of HA, EC increased from 88.62 ± 27.51 to 161.95 ± 47.80 minutes (P < 0.001). HA increased OxS level: total peroxide concentration rose from 219.38 ± 105.18 to 272.57 ± 133.39 µmol/L (P < 0.05) and oxidative stress index (OSI) from 14.97 ± 8.24 to 20.46 ± 11.13% (P < 0.05). In NHAS, the EC test increased OxS level: total peroxide concentration rose from 219.38 ± 105.18 to 278.51 ± 125.76 µmol/L (P < 0.001) and OSI from 14.97 ± 8.24 to 19.31 ± 9.37% (P < 0.01). However, in HAS, the EC test reduced OSI from 20.46 ± 11.13 to 16.83 ± 8.89% (P < 0.05). The value of log high-sensitive C-reactive protein increased from -0.32 ± 0.32 to -0.12 ± 0.34 mg/L (P < 0.05) in NHAS and from -0.31 ± 0.47 to 0.28 ± 0.46 mg/L (P < 0.001) in HAS. CONCLUSION: HA increases OxS level. However, beneficial adaptive effects of HA on acute exhaustive exercise-induced changes in OxS and inflammation parameters occur in a hot environment.

Heat acclimation decreases the growth hormone response to acute constant-load exercise in the heat.

OBJECTIVE: The major objective of this study was to elucidate the effect of heat acclimation on blood growth hormone (GH) response to moderate intensity exhausting exercise in the heat. In addition, the potential relationship between inter-individual differences in GH response to exercise and variability in exercise-induced sweat loss was investigated. DESIGN: Twenty young men completed three exercise tests on a treadmill: H1 (walk at 60% VO2peak until exhaustion at 42 °C), N (walk at 22 °C; duration equal to H1) and H2 (walk until exhaustion at 42 °C after a 10-day heat acclimation program). Core temperature (T(c)) was recorded continuously and venous blood samples were taken before, during and after each exercise test. Exercise-induced sweat production was calculated on the basis of body mass change taking into account water intake and the volume of blood samples drawn. RESULTS: Lower pre-exercise T(c), lower rate of rise in T(c) during exercise, and prolonged time to exhaustion in H2 compared with H1 revealed that the subjects successfully achieved an acclimated state. Overall, serum GH level was higher in H1 compared with both N and H2 (p<0.001) but did not differ between the two latter trials (p>0.05). T(c) correlated with serum GH concentration (r=0.615, p<0.01). Analysis of the individual data revealed a group (n=9) possessing a threshold-like pattern of the relationship between T(c) and blood GH response, whereas a plateau-like pattern was evident in the rest of the subjects (n=11). Both sweat production (r=0.596; p<0.001) and the rate of sweat production (r=0.457; p<0.001) correlated with the growth hormone area under the curve. CONCLUSION: Heat acclimation decreases the GH response to moderate intensity exhausting exercise in the heat. GH may have a modest stimulating effect on whole-body sweat production during exercise.

Heat acclimation increases arterial elasticity in young men.

The major physiological adaptations that occur during heat acclimation (HA) are well documented. However, no studies have provided compelling evidence about the effect of HA on arterial elastic properties. The aim of this study was to examine the changes in large artery elasticity (LAE) and small artery elasticity (SAE) concomitant with HA and to determine the potential relationships among changes in arterial elasticity, baseline aerobic fitness level, and improvement in endurance capacity (EC). During 10-day HA, the subjects (n = 21) exercised daily on a treadmill for 110 min at an intensity of 55%-60% of peak oxygen uptake in a climatic chamber preset to 42 °C and 18% relative humidity. EC was tested in the heat before and after HA. Arterial elasticity was assessed by diastolic pulse wave analysis (HDI/Pulse Wave CR-2000) at baseline and after HA. Blood samples were drawn at baseline. After HA, there was a 17% increase in LAE (from 21.19 ± 4.72 mL·mm Hg(-1) × 10 to 24.77 ± 5.91 mL·mm Hg(-1) × 10, p < 0.05) and an 18% increase in SAE (from 9.32 ± 1.76 mL·mm Hg(-1) × 100 to 10.98 ± 1.75 mL·mm Hg(-1) × 100, p < 0.01). EC increased by 86% (from 88.62 ± 27.51 min to 161.95 ± 47.80 min, p < 0.001) as a result of HA. No significant associations were revealed between changes in arterial elasticity parameters and improvement in EC or baseline aerobic fitness level. We demonstrated, for the first time, that HA has a positive impact on the parameters of arterial elasticity. Further investigations are needed to determine the mechanisms underlying these changes and the potential relationships among arterial elasticity, aerobic fitness level, and EC.

Dietary sodium citrate supplementation enhances rehydration and recovery from rapid body mass loss in trained wrestlers.

This study assessed the effects of dietary sodium citrate supplementation during a 16 h recovery from 5% rapid body mass loss (RBML) on physiological functions, affective state, and performance in trained wrestlers. Sixteen wrestlers performed an upper body intermittent sprint performance (UBISP) test under three conditions: before RBML, after RBML, and after a 16 h recovery from RBML. During recovery, the subjects ate a prescribed diet supplemented with sodium citrate (600 mg·kg(-1); CIT group, N = 8) or placebo (PLC group, N = 8) and drank water ad libitum. RBML reduced (p < 0.05) UBISP mean power and increased urine specific gravity (USG). Reduction in mean power was associated with changes in plasma volume (PV) (r = 0.649, p = 0.006) and USG (r = -0.553, p = 0.026). During the 16 h recovery, increases in body mass (BM) and PV were greater (p < 0.05) in the CIT group than in the PLC group. BM gain was associated with water retention in the CIT group (r = 0.899, p = 0.002) but not in the PLC group (r = 0.335, p = 0.417). Blood pH, HCO(3)(-) concentration, and base excess increased (p < 0.05) only in the CIT group. Changes in UBISP, general negative affect, and general positive affect did not differ in the two groups. In conclusion, ingestion of sodium citrate increases blood buffering capacity and PV and stimulates BM regain during a 16 h recovery from RBML in trained wrestlers. However, sodium citrate does not improve UBISP nor does it have an impact on the affective state.