Subjects
Age of the male subjects (n = 10) who took part in the study ranged from 17 to 28 years with the average of 21.2±3.3 years, whereas their training experience ranged from 5 to 21 years (11±4.5 years). Three of them had 2nd Kyu judo rank, three of the subjects had 1st Kyu and four of them had 1st Dan level.
Procedures
Body height, measured by means of Martin’s anthropometer, varied from 1.68 to 1.87 m (1.75±0.06 m). Measurements of body mass (BM) were taken with the accuracy ±1g by means of F1505-DZA Sartorius (Germany) scales. Measurements were carried out according to the recommendations in kinanthropometry [12]. The three consecutive measurements of two skinfolds (triceps and subscapular) were taken with GPM skinfold caliper with measurement range 0–45 mm ± 0.2 mm, made in Switzerland, further on intra-observer error was counted. Typical error of skinfolds measurement [13] were 1.8% for triceps, and 2.0% for subscapular. The both measurement were within proper anthropometric tolerance (5%), which is recommended for skinfolds measurements [12]. Intraclass correlation coefficients 3,1 (ICC > 0.95) show high reliability of repeated skinfolds measurements [13, 14]. Percent fat (PF) was estimated by means of the formula for white postpubescent and adult males [15], which takes into consideration the thickness of triceps skinfolds and the inferior angle of scapula. BMI and body composition indices, such as fat-free mass index (FFMI) and fat mass index (FMI) were calculated [16]. Biometrical measurements, Wingate tests for anaerobic capacity (ICC for relative peak power was 0.85 and typical error = 0.31 W·kg-1) and graded exercise for aerobic power were repeated twice in the athletes who were during preparation period. The subjects also performed the special judo fitness test, SJFT [11]. The time interval between the measurements 1 and 2 amounted to 6 weeks.
Characteristics of the training aimed at preparation for the second half of the annual training cycle
The contestants have been training for approximately 20 hours a week: 5 days for 2 two-hour-training session. During the first stage, in the beginning of the preparation period, the contestants participated in a two-week training camp which was aimed at base training before special judo training regimes and competitive seasons were started. The physical exercise was aimed at the development of endurance by means of continuous training and interval methods in the form of running and rowing. Strength training was dominated by the exercises with partners which were based on repetitions. The contestants also practiced the fight in standing position (Tachi-waza) and ground fighting (Ne-waza), which helped to solve a variety of tactical problems. Two training sessions took place every day.
During the second stage of the preparation, the subjects participated in a 4-day camp which involved fighting (Randori) twice a day. Three days later, a similar week-long camp was organized in Slovenia, where the judoists practiced sparing fights on the judo mats. The aim of this training procedure was to improve endurance and special strength and development of technical and tactical skills of sport fighting.
Next two weeks involved training with the character of direct preparation for competition and it was oriented towards the development of speed and speed endurance. Directly after this period the second testing was performed. After next five days, 7 of 10 contestants participated in the international tournament in Banska Bystrica. Five of them scored places from 1st to 5th in their weight categories (this event is not presented in the international ranking system of International Judo Federation).
Characteristics of supplementation procedure
A randomly selected study group (n = 5) was subjected to 6-week supplementation with creatine malate (“TCM”, Olimp Labs, Poland). There are different approaches for calculating the amount of creatine malate, one is that endogenic creatine for a person whose weight is 70 kg should be 2 g [17], which are lost during the day and half of this amount is synthetised in the liver. This is why 1 g should be delivered with food [18]. The optimal amount of creatine malate used for supplementation was calculated with formula 0.07 g.kg-1LBM which corresponded to 5 g of creatine malate for a person with LBM of 70 kg [19].
Every day, two hours before the breakfast, the capsules containing 0.07 g.kg-1 LBM of the preparation were administered orally, which corresponded to ca. 5 g for a person with FFM of 70 kg [19]. The supplement was dosed with 250 ml of clean, room temperature water. Other subjects were given placebo in similar capsules. The judoists did not ingest other supplements during the study. After the loading phase, the final examinations were carried out in order to determine the effect of training and supplementation on judo contestants. No statistically significant differences in age (T = 20.4±3.0, Me = 20 vs. C = 22.0±3.7, Me = 22 years, P > 0.05), training experience (T = 11.0±6.0, Me = 10 vs. C = 11±3.0, Me = 10 years, P > 0.05), and sports achievements were noticed. Judoists took part in both national and international contests. In both groups (T and C) one of the competitors was ranked in International Judo Federation. Double-blind placebo controlled design have been used.
Anaerobic test
The subject started the proper test after 5 minutes of warm-up with the intensity of 50% of VO2max using bicycle ergometer with pedaling rate of 70 revolutions per minute and three maximum acceleration bouts in 5 last seconds of the 2nd, 4th, and 5th minute and after 2-minute rest after the completion of this warm-up. The anaerobic test was a modified form of the Wingate test [20]. The load on the ergometer platters, which was optimum for each athlete, was determined during a pilot study and amounted to 8.3% of BM on average, i.e. by 0.8 higher than in the original. With this braking force, the athletes generated the greatest peak power. It consisted in pedaling for 30 seconds with maximal intensity using a mechanical bicycle ergometer Ergomedic 874E manufactured by Monark.
During the exercise, a computer recorded relative peak power (RPP) and relative total work (RTW), time to obtain peak power (toPP), time to maintain peak power (tuPP) and the fatigue index (FI).
Graded test until fatigue
A graded exercise test on a mechanical treadmill was carried out on the second day of the experiment, under similar ambient conditions. After the determination of pre-exercise circulatory and respiratory indices, the subjects performed a 3-minute warm-up at the running speed of 2.3 m.s-1, and then the speed was increased by 0.5 m.s-1 every three minutes. During the last 30 seconds of each loading segment, the subjects were taken blood samples from the earlobe in order to determine the lactate concentration in blood serum. The graded exercise was continued by the subjects until a subjective sensation of exhaustion. Using the apparatus of 919E type manufactured by Medikro, the indices of respiratory exchange were measured during the exercise every 30 seconds: tidal volume (TV), respiratory rate (F), minute ventilation (VE), minute oxygen uptake (VO2). Heart rate monitor VantageTM manufactured by Polar Electro was used for the measurements of heart rate (HR). Total time of exercise (t) and the distance (D) were also recorded. It was established based on a pilot study that the capillary blood samples used for the determination of biochemical and morphological indices would be also taken from the earlobe three minutes after the exercise. This was the point when the highest lactate (La) concentration was found. All the exercise tests were performed in an air-conditioned room in the Department of Physiology and Biochemistry of the Institute of Human Physiology. The project was approved by the Bioethical Committee at the Regional Medical Chamber (No. 76KBL/OIL/2008 of 17 September 2008).
Special Judo Fitness Test
Special Judo Fitness Test (SJFT) invented by one of the authors of the present study is an acknowledged tool of training control, implemented in many countries [11]. Visualized presentation was prepared at the University of Bath by Lance Wicks [21]. The test positively passed the statistic procedures determining the reliability and accuracy, and had normative data [11]. SJFT is a recognized tool used also in judo-related disciplines, such as ju-jitsu, hapkido etc.
Statistical analysis
The following descriptive statistics were calculated: mean, SD, median. Non-parametric methods were used, because not all parameters show normal distribution. Based on the differences between results of measurement 1 and measurement 2, the statistical significance of changes was evaluated for individual indices of body build and composition, physical capacity and fitness by means of Wilcoxon matched pairs test. The assessment of the effect of supplementation on dependent variables was based on the Mann–Whitney U test. The post-test measurement (measurement 2) is the response of the two groups (T group [n = 5]: supplementation with creatine malate; C group [n = 5]: placebo). These groups were not differed according to age, sport experience and competitive level (national and international level were presented by 4 and 1 competitors in each group). The comparisons were focused on relative data values and indices. Statistical hypotheses concerning the differences between the medians were verified at the level of significance of P < 0.05.