Cardiac Autonomic Modulation in Response to Muscle Fatigue and Sex Differences During Consecutive Competition Periods in Young Swimmers: A Longitudinal Study

Objective: To study the differences in cardiac autonomic modulation in response to muscle fatigue caused by high-intensity exercise during two consecutive competition periods in young swimmers.Methods: Twenty-six competitive swimmers, selected by their training volume, were separated in two groups, females (n = 12 [46%], age: 13.5 ± 1.4 years) and males (n = 14 [54%], age: 13.9 ± 1.7 years), aged between 10 and 16 years, were evaluated five times as follow: (i) 21 days before the first competition (t-0); (ii) two days before (t-1; t-3); and (iii) two days after (t-2; t-4) of the first and second competitions. Morphological measurements (body mass, percentage of total body fat and height), blood pressure, power, and resting heart rate variability (RR with Polar band) were recorded before and after Wingate test at each time.Results: Body fat was higher in females compared to males. However, no differences were found in other morphological parameters. An intra-subject analysis grouped by sex in cardiovascular parameters shows longitudinal variations in systolic pressure and mean pressure among females. Additionally, females depicted higher, very low frequency (VLF, which is intrinsically generated by the heart and strongly associated with emotional stress) after physical fatigue compared to males at t-1. Further, before the competition, the high frequency (HF) component of HRV (parasympathetic drive) was higher in males than females at t-0 and t-4.Conclusion: Our data revealed that males displayed greater parasympathetic reactivity after an anaerobic muscle fatigue test during their competition periods. Contrarily, females had a less cardiac autonomic modulation when comparing the pre-post Wingate test after two consecutive competition periods.

Neuromuscular Adjustments Following Sprint Training with Ischemic Preconditioning in Endurance Athletes: Preliminary Data

This preliminary study examined the effect of chronic ischemic preconditioning (IPC) on neuromuscular responses to high-intensity exercise. In a parallel-group design, twelve endurance-trained males (VO2max 60.0 ± 9.1 mL·kg−1·min−1) performed a 30-s Wingate test before, during, and after 4 weeks of sprint-interval training. Training consisted of bi-weekly sessions of 4 to 7 supra-maximal all-out 30-s cycling bouts with 4.5 min of recovery, preceded by either IPC (3 × 5-min of compression at 220 mmHg/5-min reperfusion, IPC, n = 6) or placebo compressions (20 mmHg, PLA, n = 6). Mechanical indices and the root mean square and mean power frequency of the electromyographic signal from three lower-limb muscles were continuously measured during the Wingate tests. Data were averaged over six 5-s intervals and analyzed with Cohen’s effect sizes. Changes in peak power output were not different between groups. However, from mid- to post-training, IPC improved power output more than PLA in the 20 to 25-s interval (7.6 ± 10.0%, ES 0.51) and the 25 to 30-s interval (8.8 ± 11.2%, ES 0.58), as well as the fatigue index (10.0 ± 2.3%, ES 0.46). Concomitantly to this performance difference, IPC attenuated the decline in frequency spectrum throughout the Wingate (mean difference: 14.8%, ES range: 0.88–1.80). There was no difference in root mean square amplitude between groups. These preliminary results suggest that using IPC before sprint training may enhance performance during a 30-s Wingate test, and such gains occurred in the last 2 weeks of the intervention. This improvement may be due, in part, to neuromuscular adjustments induced by the chronic use of IPC.

The effect of menstrual cycle phase on multiple performance test parameters

Objective: To determine changes in flexibility, dynamic balance, agility, vertical jump, aerobic capacity, anaerobic capacity, and muscle strength performances in women in the early follicular and midluteal phases of the menstrual cycle. Material and Methods: The study included eumenorrheic women over 18 years of age. Ovulation was detected using LH urine kits. Physical activity levels were determined using the "International Physical Activity Questionnaire-Short Form". Flexibility was evaluated with the sit-and-reach test, dynamic balance with the Y balance test, agility with the hexagon agility test, anaerobic power with the vertical jump test, aerobic capacity with the 20-meter shuttle run test, anaerobic capacity with the Wingate test, and muscle strength with an isokinetic dynamometer. Results: Twenty women participated in the study. The average age was 22.4 ± 0.9 years, and the average level of physical activity was 1162.2 ± 189.1 MET-min/week. The average menstrual cycle was 30.3 ± 0.5 days. The ‘minimum power’ value in Wingate test was higher during the midluteal phase compared with the follicular phase (p=0.048). The remaining parameters were not statistically different for the two menstrual phases (p>0.05). Conclusion: We conclude that different phases of the menstrual cycle affect performance parameters minimally and do not cause a statistically significant difference. Nevertheless, instead of establishing these changes as ‘clinically non-significant’, each athlete should be evaluated on an individual basis to develop individual training programs by taking into account the phases of the menstrual cycle.

DOES RAMADAN FASTING AFFECT DIURNAL VARIATION ON SWIMMING PERFORMANCE AND ANAEROBIC POWER?

The aim of this study is to see whether Ramadan fasting has an effect on the diurnal variations in anaerobic power and swimming performance or not. Ten participants whose mean ± SE for age, height, body mass are 19.4 ± 1.4 years, 1.72 ± 0.1 m and 72.8 ± 6.6 kg, respectively. They are tested at 3 testing periods [i.e., one week before Ramadan (BR), the middle period of Ramadan (MPR), the end period of Ramadan (EPR)], tests are performed at 07:00 h and 17:00 h throughout every course. The test sessions were started with oral temperature and body mass measurements. Regularly doing first the Wingate test then a 25-m swim at maximal speed at each test session. During the three experimental periods, dietary intake was assessed. The result shows a significant diurnal variation of muscle power and fatigue throughout the Wingate test before Ramadan. Likewise, there is a daily rhythm in the stroke parameters and swimming performance in the mentioned period. These diurnal variations change during the month of Ramadan with a decrease in power output, swim performance, swim speed and stroke length in the evening, with no changes for the morning tests. Moreover, the diurnal variations of muscle fatigue during the three morning tests show no changes and remain the same. Whereas the three evening tests show a gradual increase towards tiredness. The results show that Ramadan may has a great effect on the circadian rhythm of muscle power and swimming performance. The time-of-day effects the anaerobic power variables during the normal days which disappear during Ramadan. Ramadan fasting effects performance in the evening; however, the morning performance tests are unchangeable during Ramadan. Additionally, Ramadan fasting has no adverse effect on energy intake, and percentages of macronutrient intake. <p> </p><p><strong> Article visualizations:</strong></p><p><img src="/-counters-/edu_01/0856/a.php" alt="Hit counter" /></p>

Assessment of Adaptation Processes in the Integrated Functional Diagnostic Monitoring of Highly Qualified Athletes in Various Types of Sports

Aim: To identify the universal parameters of the functional state of athletes in various sports, which lets more fully evaluate the effectiveness of training loads. Methodology: Examining 103 highly qualified athletes aged 13-29, spiroergometry, Wingate test, electrocardiography, echocardiography, densitometry and biochemical parameters. Experimental conditions: All the participants had a preliminary medical examination and were found healthy. Participants: Athletes aged 13-29. Basic measurements: Hemoglobin level, spiroergometric test parameters, maximum and peak power in the Wingate test (30 sec), bone mineral density, stroke and minute blood volumes, heart rate. Result: a High prognostic correlation of hemoglobin parameters and anaerobic performance and the prevalence of the hypokinetic type of blood circulation in the subjects were revealed. Conclusions: The results obtained can be considered as new markers in assessing the adaptation processes in the body of athletes and can be used to monitor the health status of athletes and optimize the training process.

Abstract P134: Preliminary Data: Dietary Nitrate Supplementation Does Not Extend Dry Static Apnea Or Wingate Performance

Introduction: Previous studies have examined dietary nitrate supplementation and its effects on dry static apnea, and peak power. Dietary nitrate supplementation has been found to increase maximal apnea and peak power output. The purpose of this study was to determine the effects of beetroot juice on dry static apnea and Wingate performance. Hypothesis: Dietary nitrate will improve maximal breath hold time and peak power output. Dietary nitrate will improve tolerance to CO2, thereby improving maximal breath hold time and anaerobic capacity. Methods: In a randomized, double-blind, counterbalanced study, five healthy males (20.4±0.89 years) visited the lab on 3 separate occasions each separated by one week. Visit 1 served as a Wingate and breath hold familiarization visit. Prior to visits 2 and 3 participants were instructed to drink a beverage either a placebo (negligible nitrate content, PL) or dietary nitrate rich beverage (12.4 mmol nitrate, NIT) during the 4 days leading up to their next visit. Visits 2 and 3 consisted of two submaximal breath holds (80% of maximal determined during visit 1), with 2 minutes of rest between and three minutes of rest preceding the final breath hold for maximal duration. Finally, participants completed a standardized 10-minute warmup on the cycle ergometer before completing a 30-second maximal effort Wingate test. Results: A linear mixed effects model was used to determine whether treatment (NIT vs. PL) was associated with differences in VCO2 or PetCO2. Time (0, 10, 20, 30 min post-breath hold) and Treatment both served as repeated measures. Models were developed using multiple repeated measures covariance matrix structures, and the model with the lowest AIC was chosen as the final model. The interaction between time and treatment was included in the original models, and was removed if it was not statistically significant. Time was a statistically significant factor for VCO2 and PetCO2 (p < 0.001). Treatment, and the Time x Treatment interaction was not significant for either variable. No differences between NIT and PL were observed during the Wingate test for either time to peak power (5.02±2.45 and 6.2±2.43 sec, respectively) or maximal power (9.73±1.01 and 9.72±1.03 watts/kg, respectively) and fatigue index (49.42±14.98 and 47.30±6.99 watts/sec, respectively). Conclusion: Preliminary data indicates that in a general population four days of dietary nitrate supplementation may not improve breath hold time, tolerance to carbon dioxide in the lungs, or Wingate performance.

Acute pre-exercise supplementation of combined carnosine and anserine enhances initial maximal power of Wingate tests in humans

Classic in vitro experiments (Severin's phenomenon) demonstrated that acute carnosine supplementation may potentiate muscle contractility. However, upon oral ingestion, carnosine is readily degraded in human plasma by the highly active serum carnosinase-1 (CN1). We developed a novel strategy to circumvent CN1 by pre-exercise ingestion of combined carnosine (CARN) and anserine (ANS), the methylated analog with similar biochemical properties but more resistant to CN1. First, in vitro hydrolysis was tested by adding carnosine and anserine to human plasma, alone or in combination. Secondly, 5 subjects were supplemented with 25mg/kg anserine or 25mg/kg of each anserine and carnosine to test in vivo bioavailability. Thirdly, two double-blind, placebo-controlled, crossover studies investigated the effect of pre-exercise ANS+CARN (20mg/kg BW of each) supplementation on performance during a single all-out Wingate test following 6-minute high-intensity cycling (study A) or 3 repeated Wingate tests (study B). In vitro experiments demonstrated slower degradation of anserine vs carnosine, which was further slowed by simultaneously adding carnosine. In vivo bioavailability of plasma anserine was more prominent (2.5-fold increased AUC) when ANS+CARN vs ANS was ingested. Study A showed significantly higher (+6±11%; p=0.04) power in the first 5s of the Wingate test following ANS+CARN (12.8±2.4W/kg) vs placebo (12.1±2.2W/kg). Study B demonstrated increased peak power (+3%) throughout 3 consecutive Wingate tests (ANS+CARN 10.5±0.6W/kg vs placebo 10.2±9.9W/kg). These experiments reveal a novel acute nutritional method to effectively raise plasma anserine and carnosine by high-dose combined supplementation. This approach led to improved initial cycling power, revealing a new nutritional strategy to increase exercise performance.

Acute Effects of Caffeine Intake on Psychological Responses and High-Intensity Exercise Performance

Objective: The aim of this study was to investigate the effects of caffeine supplementation on: (i) psychological responses of subjective vitality and mood; (ii) performance through a Wingate test; and (iii) rate of perceived exertion (RPE) reported after a Wingate test. Methods: Fifteen male participants (22.60 ± 2.16 years) ingested 6 mg·kg-1 of caffeine or placebo (sucrose) supplementation in two experimental sessions. After 60 min from supplement intake, participants fulfilled two questionnaires, which measured subjective vitality and mood state, respectively. Subsequently, participants’ performance was assessed through a Wingate test, which was followed by measurements of RPE at general, muscular, or cardiovascular level. Results: Caffeine supplementation increased some components of mood, as assessed by profile of mood states (POMS) (tension and vigor dimensions) and subjective vitality profiles, which were followed by a greater maximum power, average power, and lower time needed to reach maximum power during the Wingate test. Moreover, lower RPE, both at muscular and general levels were reported by participants after the Wingate test. Conclusions: These results suggest that caffeine supplementation exerts positive effects both in psychological and physical domains in trained subjects.