The Development of the Special Brazilian Jiu-Jitsu Fitness Test: Takedown Zone (SBJJFT-TZ), Gi Formula

Featured Application

The test can be used safely and under training-room conditions to comprehensively assess the level of preparation in terms of the special fitness and performance of BJJ athletes. It is recommended that the SBJJFT-TZ test be used in other grappling combat sports disciplines where judogi is used.

Abstract

Background: There is a consensus among combat sports researchers regarding the important role of evaluating the comprehensive special fitness and performance of athletes. This is due to the specific structure of tasks performed in these sports as they require a comprehensive and integrated function of broadly understood physical fitness. The present study aimed to develop and check the Special Brazilian Jiu-Jitsu Fitness Test: Takedown Zone (SBJJFT-TZ), Gi formula’s reliability. The major task of this sport-specific tool is to illustrate the comprehensive special fitness and performance of professional Brazilian jiu-jitsu athletes. Methods: The study covered 27 BJJ athletes (age in years: 25.36 ± 2.99; height: 175.04 ± 5.70 cm; weight: 76.56 ± 8.59 kg; BMI: 24.96 ± 2.30; 6.33 ± 2.51 years of training) with a high sports skill level. A coaches’ ranking of the athletes studied according to sports achievement was developed. An experimental approach to the problem was employed, with the SBJJFT-TZ assessment, including throws and specialized locomotion, performed on two dates (seven days apart). The test parameters were recorded and, using a specialized formula, an index showing comprehensive special fitness was calculated. To verify the test’s validity and reliability, using statistical procedures, the results were comparatively analyzed (Student’s t-test for the dependent variables), and the relationships between rankings were examined (Pearson’s r linear correlation). The level of statistical significance was set at p < 0.05. Results: The analyses showed statistically significant relationships with very high strength between coach ranking and SBJJFT-TZ parameters for both dates (R = 0.73–0.88; p < 0.001). A similar trend of significant correlations was noted between the first and second SBJJFT-TZ dates (R = 0.96–0.98; p < 0.001), and the strength of the coexistence was almost complete. The test-retest procedure for SBJJFT-TZ showed similar levels for the parameters studied, without significant variation (p > 0.05) but with a weak effect profile (d = 0.03–0.06). Internal variation in the variables was very low (HR CV < 10%) and moderate (Throws and Index CV = 20.82–32.25%). Significantly different throwing performance between sets was shown, with an advantage in the first round of work compared to the second, and a moderate effect (p < 0.05; d = 0.38–0.39). Conclusions: The identification of relationships, the comparison, and the test-retest procedure showed the high application value of SBJJFT-TZ. The proposed tool provides a reliable cross-sectional evaluation of BJJ athletes’ special fitness and performance in the stand-up fighting plane, as well as at the moment of achieving an advantage over the opponent, and favors implementation in field conditions.

1. Introduction

In combat sports, fitness levels can be evaluated using general tests and specialized laboratory measurements [1]. However, the results of these examinations do not always reveal positive relationships with performance during sports competitions [2]. Sport-specific fitness tests have been successfully used in addition to general fitness measurements [3,4,5,6]. Under the conditions of such tests, the athlete experiences a response to the specific effort that is needed in a sports bout [7,8]. This makes it possible to monitor training adaptations in terms of special (sport-specific) fitness, the level of technical and tactical excellence, and the speed and quality of its application in combat [9]. Special tests should be based on the technical elements of the sport and the various parts of the bout [5,10].

Brazilian jiu-jitsu (BJJ) is a hybrid combat sport based on a compilation of traditional jiu-jitsu, judo, and wrestling [11]. Bouts occur on the mat between two opponents, who use only grappling (grappling combat sports) techniques. A rich array of specialized offensive (single attacks or attacks performed in a series) and defensive actions is used to gain an advantage over the opponent or counter his or her activity [12]. The classification of competitors and fight times is based on belt division (technical–tactical excellence and sports skill level), weight category, age category, and gender. A bout can be won before the standard time (submission, injury, or disqualification) on points or advantages (supremacy of points or technical advantages), and, in the absence of these, by the referee’s decision [13]. To meet the demands of training and sports competitions, a good athlete should be characterized by a comprehensive spectrum of motor skills and a broad array of technical and tactical skills, combined with excellent physical and mental performance [14,15].

Competition in BJJ includes fighting in two planes: standing (distance and then clinch fighting with the use of throws, takedowns, or pulling guard in order to move to ground fighting) and lying down (ground fighting with the use of joint locks, chokeholds, sweeps, and also scored technical positions) [11]. Most of the fighting takes place in the priority ground plane [16]. In contrast, stand-up fighting is essentially secondary, unlike in similar combat sports such as judo and wrestling. Nevertheless, this phase of combat is one of the pillars of the BJJ training. It is on this plane that a sport fight begins. Competitive and coaching experience and related observations show that successfully performed judo throws or wrestling takedowns are admired by spectators and are highly valued in this sport, providing the athlete with technical points that can determine their final success. In addition, an optimally performed takedown can limit an opponent’s movements, making it far easier to win or control a fight. BJJ requires a controlled takedown with a temporal (3 s) positional advantage from above (a condition for scoring technical points) [13]. In addition, an effective takedown is essential for fighters who prefer the model of fighting from above (known as guard passers), because it allows them to impose their style of fighting in BJJ matches. These observations are confirmed by the opinion of one of the greatest authorities of the coaching community in this sport [17].

BJJ is divided into two sub-sports in which a bout takes place: NoGi (fighting while wearing shorts and a grappling rash guard) and Gi (fighting in judogi, a specificity partly similar to judo) [13]. Due to the use of judogi, the Gi formula favors the performance of judo throws. Most effective in BJJ are throws from the Sutemi-waza and Ma-sutemi-waza groups, such as Sumi gaeshi (S-G) and Tomoe nage (T-N), as confirmed by coaching authorities [17] and empirical athletic and coaching observations. Both techniques of S-G and T-N, if unsuccessful, allow the fight to continue smoothly in Ne-waza (the ground-fighting plane) by instantly pulling on the guard. During the throw performance, the attacker controls the opponent in a way that makes it difficult to use counterattacks and guard-passing in BJJ (the transition to Osaekomi-waza in judo) in Ne-Waza [18,19,20].

A perfect example of this fighting model is exhibited by the three-time and current world champion of the lightest women’s category (−48 kg) in judo [21], as well as by the current Olympic champion (+100 kg) of Tokyo 2020 (as of 24 July 2021) in his key technical action in the final fight [22]. Based on both subjective and qualitative inferences, high technical competence in the application of S-G and T-N can also be crucial in ground fighting, where specialized sweeps (rolling the opponent from a guard position on their back to horizontal control from above) are used to gain an advantage in technical points. Sweeps such as the Tomoe nage sweep, from the De La Riva Guard [23], or the butterfly guard sweep [12], with their mechanics and execution techniques, are very reminiscent of the throws discussed here. Furthermore, a team of Brazilian researchers developed and presented a specific anaerobic capacity test in the ground-fighting plane for BJJ athletes (Jiu-Jitsu-Specific Anaerobic Performance Test—JJAPT) [24] and its effectiveness in the special preparation of BJJ athletes [25,26]. The test was based on the key element of dominating the opponent’s center of gravity, the butterfly guard sweep, which is very similar to the work performed in S-G and T-N. This technical element is the basis for achieving an advantage over the opponent (including knocking them off balance and performing a sweep) [24]. However, this test and its main tested element focus just on the groundwork, which is just one part of a BJJ. Therefore, a test that includes wider BJJ movement variations and space–time settings closer to the BJJ is needed.

In the search for a comprehensive diagnosis and evaluation of the pillars of BJJ and the implementation of special fitness tests, it is worth considering the possibility of spatial construction based on a combination of useful throwing techniques (i.e., T-N and S-G), not only from the aspect of an effective throw but also with the desired control of takedowns from above in BJJ and a specialized form of locomotion. This type of action will identify the level of special fitness, as well as the potential of the athlete to conduct intense positional fighting. This is mainly determined by the potential of the anaerobic system, strength and speed fitness, and technical skill level [27,28]. Therefore, the BJJ special fitness test should be developed and standardized based on these areas. This fact has inspired our scientific exploration to optimize the training process. A research team specializing in combat sports attempted to develop and validate a special BJJ fitness test. The purpose of this study was to design and verify whether a 60-s (2 rounds of 30 s each) fatigue test with the implementation of selected throws, the participation of two partners, and implementation in the spatial arrangement has a reliable diagnostic value and can be used to assess the special fitness in BJJ fighters in the stand-up fighting plane. The test was named the Special Brazilian Jiu-Jitsu Fitness Test—Takedown Zone (SBJJFT-TZ).

2. Materials and Methods

2.1. Study Participants

The study covered a group of 27 professional Brazilian jiu-jitsu athletes (only males). The sample size was determined using G*power 3.1.9.7. (confidence level 95%; margin of error 5%). The group consisted of at least 4 representatives each from 6 adult Gi formula weight categories (n = 4 to 64 kg, n = 4 to 70 kg, n = 4 to 76 kg, n = 6 to 82.3 kg, n = 5 to 88.3 kg, n = 4 to 94.3 kg), according to the International Brazilian Jiu-Jitsu Federation (IBJJF) regulations (24). The mean body mass of the participants was 76.56 kg ± 8.59 and the mean body height was 175.04 cm ± 5.70 (BMI = 24.96 ± 2.30). An A213 anthropometer was used for body height measurement evaluation and a certified TANITA TBF-538 (TANITA, Tokyo, Japan) electronic scale was used for body mass measurement according to the anthropometric recommendations [29]. Inclusion criteria for the study were: at least 4 years of training experience; no presence of musculoskeletal injuries; good health status, as confirmed by medical examinations, with a positive medical recommendation; no history of serious injuries; and active participation in competitions. The ages of the tested athletes ranged from 21 to 31 years (mean age: 25.36 years ± 2.99). Training experience ranged from 4 to 14 years of regular training, with 4 to 6 training sessions per week, depending on the training mesocycle (mean experience: 6.33 years ± 2.51). Belt colors were from white to black (N = 4 black belts, N = 7 brown belts, N = 8 purple belts, N = 6 blue belts, and N = 2 white belts). The examinations were performed in the athletes’ preparatory period. Participants were not on a restrictive diet or on any weight-loss regimen. All the participants had participated in international, national, and local elite competitions. Some had achieved significant sports results, including medals in European, Polish, and other prestigious grappling competitions. Information on chronological age, activity, and competitive experience was obtained based on a diagnostic survey conducted on athletes and coaches. All participants were informed in detail about the experimental procedure and provided written consent to participate in the experiment. The study was conducted according to the Declaration of Helsinki and was approved by the Bioethics Committee at the District Medical Chamber in Krakow (No. 226/KBL/OIL/2023).

2.2. Study Design

The research was conducted according to the schedule shown in Figure 1.

2.3. Research Methods

Two specialized research tools were used in order to check the reliability and validity of the special fitness test:

• Competition success ranking (CSR).
• Special Brazilian jiu-jitsu fitness test, takedown zone, Gi formula (SBJJFT-TZ).

2.3.1. CSR

Motivated by diagnosing the relationship between SBJJFT-TZ scores and athletes’ sports performance, a competition success ranking was developed based on athletes’ achievements during their sports careers (validity verification). The time frame of sports achievements covered the entire career in the senior category. Information about achievements was gathered from athletes and coaches and was then confirmed through an official communication specific to each individual sports event. The coaching staff compiled the ranking. The procedure for identifying an athlete based on the criterion of sports performance was as follows: in BJJ, the key characteristics were used from athletes who achieved the highest point scores, calculated based on:

• World Championship medal—7 points;
• European Championship medal—5 points;
• Polish Championship medal—4 points;
• Polish Cup medal—3 points;
• BJJ League medal—2 points;
• Tournament medal of other unlisted competitions based on ground grappling—1 point;
• In the case of fighters without the above achievements, their ranking was determined according to the number of fights won in BJJ and ground grappling tournaments, where each winning bout scored: World Championship—0.7 points; European Championship—0.5 points; Polish Championship—0.4 points; Polish Cup—0.3 points; BJJ League—0.2 points; other tournament—0.1 points.

At the time of the measurement, the BJJ collective included a total of 27 athletes; 22 of these athletes had achievements in the form of tournament medals and 5 had won a minimum of 1 tournament bout. There was no athlete with achievements from the World Championships. The result of the ranking points of the examined athletes fell within the range of 0.1 p to 58 p, with a mean of 14.73 ± 15.27.

2.3.2. Special Brazilian Jiu-Jitsu Fitness Test: Takedown Zone (SBJJFT-TZ), Gi Formula

1.

Preparation of the participants for testing performance.

Prior to performing the test, participants performed a warm-up that included 5 min of light running and 10 min of general warm-ups and stretching (flexibility and mobility) exercises. The exercises included shoulder work (raises, lowers, and rotations), torso exercises, head exercises (bends, twists, and combined bends with twists), and leg exercises (swings, rotations, and jumps), in various planes of motion (sagittal plane forward and backward, frontal plane, transverse plane, and compound movements), following gymnastic principles [30]. Moreover, the participants performed gymnastic exercises tailored for Brazilian Jiu-Jitsu (forward and backward rolls, side and forward flips, and escapements from the head and neck, as well as various types of judo falls (self-assurance): forward, backward, and sideways [12]. Afterward, the test demonstration followed. Then, at a slow pace, techniques and special locomotion as performed in the test were practiced several times, in order to become accustomed to the spatial arrangement of the test, tasks, and other participants. Each participant performed a preliminary set of 8 throws and 8 locomotions, as specified in the test. The warm-up and test demonstration were performed on a tatami mat sized 2 m × 1 m × 5 cm. Participants (N = 27) were divided into 3-person groups with similar body mass (±2 kg) and height (±5 cm). Each uke, who then became the tori, was subject to a minimum 15-min break.

2.

Material and teaching resources.

To perform the test, the following items were used: a tatami mat (min. 16 square meters), a tape measure, adhesive tape to mark the tori‘s starting point and the uke’s position on the mat, a stopwatch, 3 physically fit participants (team selection, that is, a tori and two uke’s of similar body mass and body height), a protocol form for recording the results, and a heart rate monitor. The rate of heart contractions in tests was recorded using a Polar (Finland) 610S sport tester.

3.

SBJJFT-TZ (test implementation).

The interval fatigue test consisted of 2 30-s work periods (30 s—round I; 30 s—round II) separated by a 10-s rest of a passive nature. The 2 participants that will be thrown (uke 1 and 2) are positioned in the standing position, facing each other in a straight line, at a distance of 6 m (lower limbs spread apart, slightly bent at the knee joints; upper limbs spread out to the sides). These places are marked with tape (positions S1-uke1, S2-uke2 in Figure 2). The tested athlete (tori) takes the starting position or SP (fighting position, standing) in the middle of the 6-m distance, facing forward toward uke 1 (S1). On the command “Start!”, the participant begins Round I by performing the following movement task: he/she moves as fast as they can in a straight line to uke 1 (S1) and the method of locomotion at this distance is to perform an asymmetrical forward roll over the shoulder with a break-fall (Japanese: zempo ukemi—chiugarei [18]). Next, the participant performs an S-G throw on uke 1, with control from above (position: mount, lateral, or guard, with no time limit to mark). Then, the participant repeats the same cycle (locomotion and throw) toward uke 2 (S2). Immediately after executing the throw, uke 1 and uke 2 return to their initial positions (S1-uke1, S2-uke2). The participant repeats this sequence for the entire 30-s period. The command “Stop!” marks the end of the first round, with a passive break of 10 s in which the tori moves back to the starting position or SP. Once the break ends, the second round starts from the same initial facing position. The workflow is the same and the difference is in the use of a different throwing technique, i.e., T-N. Throwing and rolling techniques are performed by the tori with the dominant side. The total time of the specialized effective work in the test performed is 60 s (2 × 30 s), and the passive time is 10 s of breaks between rounds, while the total time is 70 s. Each throw and roll should be performed at maximum speed by the participant. The focus is on intense exercise, involving the performance of the highest possible number of repetitions of techniques within a procedurally determined time limit. The behavior of each uke is entirely passive, without offering resistance or assistance, and can be described in 3 phases: first phase—waiting in position for the tori to execute the throw; second phase—passive behavior during the throw; third phase—immediate return to the initial position, which remains unchanged throughout the test (S1-uke1, S2-uke2). The execution of the test has been included as a video in the Supplementary Material.

Figure 2 illustrates a global diagram of the test. It outlines the location and order in which each test task is performed, along with the way and direction in which the participant moves.

Description of the throwing technique and locomotion element used in SBJJFT-TZ:

Zempo ukemi–chiugarei (Z-U-C): After a few steps of run-up, the participant performs a take-off with the lead leg, while the rear leg, using a backward sweep, initiates the body’s rotation in the flight phase. The next step is to jump onto the shoulder from the side of the lead leg. As soon as the body’s weight is transferred to the shoulder, flexion occurs by pressing the head toward the chest and keeping the upper body arched. Rolling in contact with the ground occurs through the shoulder, the lateral part of the body trunk, and the hip, landing in a lying position, sideways. Figure 2 depicts the initial setup of uke 1 and 2, as well as the central tori during the execution of Z-U-C (flight phase).

Sumi-Gaeshi (S-G): The tori performs kumi-kata on the uke (right/left hand grasping the belt on the back, after putting the arm over the left/right (l/r) shoulder of the uke, possibly grasping the l/r collar, while the l/r hand grasps the r/l sleeve—optimally, halfway down the length of the forearm). The tori leans with the uke on top of himself/herself, and moves deep under the uke by lying on his/her back, while hitting the uke’s thigh (l/r) from the inside with a leg (r/l) [18]. Ultimately, the tori aims to roll behind the uke (roll backward with the opponent) for the control from above that is desired in BJJ (Figure 3).

Tomoe-Nage (T-N): The tori performs kumi-kata on the uke (r/l hand grasp for the l/r collar, while the l/r hand grasps the r/l sleeve). The tori then pulls dynamically to bring the uke’s body downward (the automatic defensive reaction is often to extend the torso), then moves far underneath the uke by lying on their back, while lifting his/her hips with the foot (r/l) placed near the uke’s hip girth [18]. The tori aims to roll behind the uke (rolling backward with the opponent) for control from above, as desired in BJJ. In this aspect, the prior positioning of the supporting foot (opposite to the lever foot) in the area of the popliteal fossa (r/l) of the uke is helpful (moreover, this makes gymnastic defense more difficult) (see Figure 4).

4.

Measurement of the SBJJFT-TZ parameters.

Properly performed techniques were recorded for each of the 2 rounds of work (a quantitative arbitrator and video recording). The correctness was confirmed by 3 elements of technique (1—the positioning of the lifting leg: S-G on the inner side of the uke’s thigh, T-N around the hip area; 2—the execution of both S-G and T-N by falling on the back; 3—completion of the throw with a top position such as the mount, side, in guard, or half-guard), controlled by a specifically designated technical arbiter. Subsequently, verification was reassessed through video retrospection. The heart rate (HR, bpm) was then measured immediately after the test (Final HR) and the recovery heart rate was measured 1 min after completion (HR 1 min). Based on Sterkowicz’s formula developed for JUDO and the special judo fitness test (SJFT) [5], the adapted formula was developed. The formula for the present test comprises the sum of post-exercise HR measurements and measurements after 1 min of rest (SHR), divided by the sum of the techniques correctly performed in 2 rounds (SR). The final outcome of the formula is the SBJJFT-TZ special fitness index. The formula is presented below:

$$\mathbf{SBJJFT-TZ} \mathbf{Index}=\frac{\mathbf{Final}\mathbf{HR}\left(\mathbf{b}\mathbf{p}\mathbf{m}\right)+\mathbf{HR}\mathbf{1}\mathbf{min}.\left(\mathbf{bpm}\right)}{\mathbf{R}\mathbf{1}\left(\mathbf{l}.\mathbf{p}.\right)+\mathbf{R}\mathbf{2}(\mathbf{l}.\mathbf{p}.)}$$

where:

Final HR—heart rate recorded immediately after completion of the test

HR 1 min.—heart rate recorded 1 min after the completion of the test

R1—number of repetitions of throws in round 1

R2—number of repetitions of throws in round 2

The SBJJFT-TZ index reflects the BJJ athlete’s level of special fitness in the stand-up fighting plane, which means the effective interaction of the body’s exercise capabilities, general fitness, and the quick application of BJJ technical moves. The interpretation of the score is inversely proportional: the higher the level of special fitness, the lower the value of the index.

The maximum heart rate of each subject was calculated using the latest formula developed for this variable: HR max = 202.5–0.53*age [31], in order to assess the percentage contribution of Final HR achieved by BJJ athletes at the end of the 70-s load SBJJFT-TZ.

2.4. Testing Procedures (Experimental Approach to the Problem: Test-Retest)

The research was conducted in August 2023, in the facilities of KS Legion Team, Tarnow. Before the measurements, participants were carefully instructed on how to perform all steps of the examination process.

The verification of the author’s test was carried out as follows:

• During the first measurement unit, participants performed the SBJJFT-TZ I special test in a randomized order. Upon completion of the measurement tests, the number of correctly performed throws was recorded for each participant, and their heart rate (HR) was measured.
• Seven days later, the participants repeated the SBJJFT-TZ test according to the author’s procedure (SBJJFT-TZ II). The order of performing the trial by the participants was also subject to randomization.

After completing the two-step measurement process, the special fitness index was calculated for both test dates, based on the results obtained, to confirm the reliability of the test. The measurements were aimed at diagnosing validity and verifying whether the proposed SBJJFT-TZ test using directional throws for BJJ and specialized locomotion positively correlated with the developed coach ranking and the second SBJJFT-TZ measurement date. The aim of the evaluation of test reliability was to examine the level of variation in the SBJJFT-TZ parameters for comparison between the first and second measurements.

2.5. Statistical Analysis

To process the results of the study, basic statistical methods were used to determine the arithmetic means, standard deviations, minimum and maximum values, lower and upper quartiles, and coefficients of variation. The degree of intragroup diversity was assessed by interpreting the coefficient of variation values according to the following classification: CV < 25% indicates low variability; 25–45% indicates moderate variability, 45–100% indicates high variability; >100% indicates very high variability [32]. The normality of distribution was verified and confirmed using the Shapiro–Wilk test. Due to the lack of normal distribution for the CSR variables, the calculations were performed on data transformed using the Box–Cox method. Pearson’s r linear correlation was used to assess the relationship between the variables studied. The inference thresholds for the correlations were r = 0.0 to 0.19 for a very weak correlation, r = 0.20–0.29 for a weak correlation, r = 0.30–0.49 for a moderate correlation, r = 0.50–0.79 for a strong correlation, and r > 0.80 for a very strong correlation. The degree of variation between SBJJFT-TZ I and SBJJFT-TZ II was assessed using Student’s t-test for the dependent variables. Furthermore, the effect size was calculated using Cohen’s d index (d = 0.20, weak effect; d = 0.50, moderate effect; d = 0.80, strong effect). Analysis of the collected material was conducted using Statistica software (version 13.3, StatSoft, Kraków, Poland).

3. Results

Table 1. Correlation coefficients between SBJJFT-TZ parameters (first and second dates) and coach ranking.

Parameter	r	p
SBJJFT-TZ I-first date (SR) vs. CSR	0.83	<0.001 *
SBJJFT-TZ I-first date (SHR) vs. CSR	−0.87	<0.001 *
SBJJFT-TZ I-first date (Index) vs. CSR	−0.73	<0.001 *
SBJJFT-TZ II-second date (SR) vs. CSR	0.88	<0.001 *
SBJJFT-TZ II-second date (SHR) vs. CSR	−0.86	<0.001 *
SBJJFT-TZ II-second date (Index) vs. CSR	−0.75	<0.001 *

r—Value of the correlation coefficient, p—level of significance; SBJJFT-TZ I—value of the parameters from the first test date; SBJJFT-TZ II—value of the parameters from the second test date; CSR—value competition success ranking; (SR)—total throws; (SHR)—total heart rate measurements; (Index)—special fitness index; * p < 0.05.

shows the values of the correlation coefficients of the study population, between the CSR and the proposed SBJJFT-TZ test (carried out on two different dates), against selected test variables. Statistically significant relationships of very high strength were found on the first measurement date for the compared parameters. There was a negative direction of correlation for the sum of the heart rate and special fitness index and a positive direction for the sum of the throws.

A similar trend of correlations was recorded between the ranking (CSR) and SBJJFT-TZ II performed at the end of the study period, showing statistically significant correlations with very high strength and the same direction profile (Table 1).

Table 2. Correlation coefficients between the two SBJJFT-TZ measurement dates (I, II terms) for the parameters of total throws, total HR, and the special fitness index.

Parameter	r	p
SBJJFT-TZ I-first date (SR) vs. SBJJFT-TZ II-second date (SR)	0.96	<0.001 *
SBJJFT-TZ I-first date (SHR) vs. SBJJFT-TZ II-second date (SHR)	0.98	<0.001 *
SBJJFT-TZ I-first date (Index) vs. SBJJFT-TZ II-second date (Index)	0.98	<0.001 *

r—Value of the correlation coefficient; p—level of significance; SBJJFT-TZ I—value of the parameters from the first test date; SBJJFT-TZ II—value of the parameters from the second test date; (SR)—total throws; (SHR)—total heart rate measurements; (Index)—special fitness index; * p < 0.05.

shows the correlation coefficients between the first and second SBJJFT-TZ measurements. For all diagnostic test parameters, a positive correlation strength of almost full statistical significance was demonstrated.

Table 3. Statistical characteristics of the SBJJFT-TZ parameters from two measurement dates.

Parameter	$\overline{\mathbf{x}}$	SD	Min	Max	Q1	Q3	CV%	p	d
SBJJFT-TZ I-first date (R1)	5.78	1.55	3	8	4.50	7.00	26.87	0.42	0.05
SBJJFT-TZ II-second date (R1)	5.85	1.46	3	8	5.00	7.00	24.95
SBJJFT-TZ I-first date (R2)	5.26	1.10	3	7	5.00	6.00	20.82	0.54	0.06
SBJJFT-TZ II-second date (R2)	5.33	1.21	3	7	4.00	6.00	22.67
SBJJFT-TZ I-first date (SR)	11.04	2.53	6	15	9.50	13.00	22.96	0.29	0.06
SBJJFT-TZ II-second date (SR)	11.19	2.59	6	15	9.50	13.00	23.13
SBJJFT-TZ I-first date (Final HR)	183.26	6.68	173	195	177.50	187.50	3.64	0.38	0.04
SBJJFT-TZ II-second date (Final HR)	183.56	7.56	172	198	178.00	189.00	4.12
SBJJFT-TZ I-first date (HR 1 min)	156.63	11.35	139	173	145.50	169.50	7.25	0.46	0.04
SBJJFT-TZ II-second date (HR 1 min)	157.04	10.33	140	173	146.50	167.50	6.58
SBJJFT-TZ I-first date (SHR)	339.89	17.24	313	363	323.00	357.00	5.07	0.27	0.04
SBJJFT-TZ II-second date (SHR)	340.59	17.28	312	363	323.50	359.00	5.07
SBJJFT-TZ I-first date (Index)	33.11	10.68	20.87	59.00	24.89	37.85	32.25	0.36	0.03
SBJJFT-TZ II-second date (Index)	32.75	10.39	18.35	60.50	24.89	37.90	31.74

$\overline{\mathrm{x}}$—Arithmetic mean, SD—standard deviation, min—minimum value, max—maximum value, Q1—bottom quartile, Q3—upper quartile, CV%—coefficient of variation, Student’s t-test, p—level of significance of variation, Cohen’s d—variation effect size, SBJJFT-TZ I—value of parameters from the first date of the study; SBJJFT-TZ II—value of the parameters from the second date of the study; (R1)—throws of round 1, (R2)—throws of round 2, (SR)—total throws, (Final HR)—heart rate immediately after the test, (HR 1 min.)—heart rate 1 min after the test, (SHR)—sum of heart rate measurements; (Index)—special fitness index.

shows a comparison of the test parameters obtained on the two SBJJFT-TZ special test dates. For both dates, the results of the parameters studied were shown to be similar, without signs of significant variations, and with a weak effect profile. The first test date generated slightly lower (more favorable) values of heart rate globally, i.e., immediately after completion of the test and one minute later, and consequently, of the sum of measurements of the variables. In contrast, the second date of SBJJFT-TZ II showed non-significantly higher values relative to the global throwing parameters and a slightly lower special fitness index.

The maximum heart rate of the studied population was estimated at HR max = 189.06 bpm. The Final HR achieved by the subjects in SBJJFT-TZ I was 96% of HR Max, while in SBJJFT-TZ II, it was 97%.

The parameters of the coefficient of variation, evaluated based on the SBJJFT-TZ test-retest procedure, show that on both measurement dates, the internal variation of the analyzed variables was very low in the case of both vascular and circulatory stress parameters (CV < 10%). Moderate internal variation (CV = 20.82–32.25%) was shown for the parameters of throwing and special fitness indices.

For a comprehensive analysis of the takedown area (Round 1—TOME-NAGA vs. Round 2—SUMI-GAESHI;

Table 4. Statistical characteristics of the throwing parameters in SBJJFT-TZ (first and second dates) from two thematic rounds (R1 vs. R2).

Parameter	$\overline{\mathbf{x}}$	SD	Min	Max	Q1	Q3	CV%	p	d
SBJJFT-TZ I-first date (R1)	5.78	1.55	3	8	4.50	7.00	26.87	0.006 *	0.39
SBJJFT-TZ I-first date (R2)	5.26	1.10	3	7	5.00	6.00	20.82
SBJJFT-TZ II-second date (R1)	5.85	1.46	3	8	5.00	7.00	24.95	0.001 *	0.38
SBJJFT-TZ II-second date (R2)	5.33	1.21	3	7	4.00	6.00	22.67

$\overline{\mathrm{x}}$—Arithmetic mean, SD—standard deviation, min—minimum value, max—maximum value, Q1—bottom quartile, Q3—upper quartile, CV%—coefficient of variation, Student’s t-test, p—level of significance of variation, Cohen’s d—variation effect size, SBJJFT-TZ I—value of parameters from the first date of the study; SBJJFT-TZ II—value of the parameters from the second date of the study; (R1)—throws of round 1, (R2)—throws of round 2; * p < 0.05.

) and the fatigue-inducing nature of the test, it was observed that on both measurement occasions, the work performed, which was expressed as the number of correctly executed throwing techniques, exhibited significant variation. Significantly higher efficacy was shown for the first round (S-G) of special test activity compared to the second series of throws (T-N), with a moderate effect.

4. Discussion

The present study’s aim was to develop a special test to diagnose the specific fitness of athletes in the stand-up fighting plane, in terms of the widely understood special fitness and exercise performance of practitioners of Brazilian jiu-jitsu (BJJ). We made sure that the diagnosis, on the one hand, did not require complex apparatus and, on the other hand, that the tests could be performed under training room conditions. In order to effectively use tests to evaluate athletes, they must be valid and reliable [33]. Therefore, the further discussion of results is divided into validity and reliability sections.

4.1. Validity of SBJJFT-TZ

According to sports theory, validity, among other things, reflects whether a test measures a desired attribute (e.g., motor ability, maximal aerobic capacity, or anaerobic capacity) for a given sport specificity [33]. Effective performance measures in sports should emphasize skill components that are closely related to the specific sport and address functional movements integral to that activity [34,35]. It was suggested that in combat sports, the designed tests should particularly consider movements involving short bursts of speed and changes of direction in order to adequately evaluate anaerobic fitness [35]. Validation is usually performed against an already validated tool or test with high ecological validity. However, in our case, there is a lack of BJJ special tests. One of the rare tests, the BJJ JJAPT test [36], differentiates from ours in terms of time and movement structure. Therefore, another measure of performance needs to be taken into account to validate the test measures of special performance. Higher special fitness testing in combat sports was connected to higher physical fitness [37], which has been shown to successfully predict sporting success in combat sports [38,39,40]. Different rankings have been widely used in various other sports [41,42,43] and in combat sports as a valid measure of the competition success of athletes [44,45,46,47,48].

Therefore, to verify the validity of the SBJJFT-TZ test, we analyzed its results and the correlations from both dates occurring in comparison with the coach ranking. Based on this analysis, significant and very strong relationships were found, indicating that performance on test tasks was highly correlated with the participants’ sports skill level. This supports the thesis that this research tool is valid [49,50]. Athletes with higher levels of achievement were characterized by better values for the test parameters. They had lower values of final heart rate and HR measured after one minute (negative correlations), and recorded more specific techniques performed (positive correlations), which finding was ultimately illustrated by lower, and therefore better, indices of special fitness (SBJJFT-TZ index, with negative correlations).

The results of the present study revealed a similar trend for both test dates in terms of the reduced frequency of the movement activity (number of repetitions) in the second round of work. The throws of the first round were characterized by a significantly higher efficiency in terms of the number of repetitions. Our test allowed for the evaluation of the anaerobic capacity due to deterioration when recording the poorer performance caused by fatigue in the second round. This is also indicated by the elevated heart rate measured at the end of the test on both measurement dates. The cardiovascular stress parameters indicated that in the study population, the test was characterized by very high exercise intensity, comparable to a tournament bout, as the heart rates recorded immediately after the tests ranged from 172 to 198 bpm (Final HR on date 1: $\tilde{\mathrm{x}}$ = 183.26 ± 6.68; on date 2: $\tilde{\mathrm{x}}$ = 183.56 ± 7.56). The results obtained in the study are consistent with data from the literature indicating that in trained athletes, intense exercise based on unarmed combat techniques results in an increase in the minute heart rate that ranges between 165 and 185 beats per minute [51,52]. Furthermore, the HR values from our study are similar to those obtained in a population of athletes after their bouts during the 2005 BJJ World Championships ($\tilde{\mathrm{x}}$ = 182.6 bpm) [53]. The aforementioned data confirm that the exercise activity performed during SBJJFT-TZ was mainly anaerobic and the energy supply route was predominantly from glycolytic anaerobic sources. In view of the above-mentioned aspects, similar observations were found in other published and successfully functioning special fitness tests for combat sports [5,6,8,9,24,54]. This indicates the similar requirements of our test in terms of broadly understood special fitness and performance assessment.

In light of previous findings reported on BJJ, it appears that the structure of the bout is characterized by motor activities of high, moderate, and low intensity, often varying during sports competition, which requires high exercise capacity, comprehensive technical and tactical preparation, and adequate strength and conditioning [15]. It is difficult to unequivocally assess the contribution of the priority energy supply system in BJJ bouts, given that it involves a wide range of specific techniques, different tactics, fighting styles, bout time (5 to 10 min), and direct contact with the ground and the opponent [14,53,55]. Anaerobic energy efficiency, power, and muscular strength determine the effectiveness of moments that determine a win (submissions before time, i.e., joint locks and chokeholds), or an advantage over the opponent (scoring technical actions: throws, takedowns, rolls, or guard passing) [56,57], with a high energy demand [58]. Using qualitative inference, the special stimulus used in the SBJJFT-TZ test allowed for the measurement of the determinants of the achievement of a significant advantage over an opponent in a BJJ match. The parameters of the test allow a cross-sectional inference of the quality of the athlete’s special preparation. The interpretation of the number of correctly performed throws per unit time helps to assess the quality of strength/velocity and strength/endurance abilities [33,59]. The proposed tool also allows for the assessment of the quality of the technical skill level of the athletes in terms of positional stand-up fighting, which is one of the pillars of the offensive capabilities of the sport [11]. The technical skills used in the test ensure its selectivity, making it inaccessible to those who do not perform special training and do not have the appropriate level of technical proficiency. Final HR values immediately after the test illustrate the level of cardiovascular fitness, while the HR measured one minute after the completion of the test indicates the level of efficiency of post-exercise recovery [5,59]. The test also examines motor coordination (smoothness of transition from the throwing technique to the gymnastic technique) and competency in additional skills (movement using a forward roll, which often occurs in various forms and compilations in the sport). The interpretation of the SBJJFT-TZ index provides a multifaceted and cross-sectional diagnosis of the special fitness and performance of the Brazilian jiu-jitsu athlete, which, globally, represents an important synergy of the diagnosed areas. In coaching practice, this information can be helpful in selecting, controlling, and planning individualized goals for the training process.

4.2. Reliability of SBJJFT-TZ

A test is reliable if its results are similar and, thus, reproducible after the athlete has been tested several times over a short period [33]. To assess the reliability of the SBJJFT-TZ test, its results were analyzed in relation to the degree of variation, at two measurement dates separated by a seven-day break. It was shown that there were no significant differences between the recorded parameters: throws (R1, R2, SR), heart rates (Final HR, HR 1 min, SHR), and the effect of special indices. There were also almost fully significant correlations between the measurements. Such results confirm the test’s reliability in the area of its repeatability [60]. Furthermore, the test-retest reliability procedure that was used showed very low and moderate internal variability of the parameters for both measurements, demonstrating this research tool’s reliability.

In the opinion of the authors of this paper, further research among grapplers seems warranted. Based on the results of our research, it is possible to identify directions for scientific exploration, with its aims including test modification or developing a new special research tool for the sports (or disciplines, such as BJJ NoGi) in which judogi (Gi) is not used, and developing an experimental training regimen that will positively affect the level of special fitness of BJJ athletes tested with SBJJFT-TZ. Future activities should take into account the identification of links with sports bouts, and the diagnosis in a group of female athletes.

4.3. The Transition of SBJJFT-TZ to Other Combat Sports

It is recommended that the SBJJFT-TZ be used in other grappling combat sports where traditional clothing (judogi) is used, such as judo, kosen judo, sport jiu-jitsu (fighting and ne-waza formulas), and sport grappling (Gi formula), due to the occurrence of these techniques and similar moments in the fighting structure for these sports. In judo and jiu-jitsu (fighting), in particular, regular diagnosis is recommended for athletes who, due to their individual fighting models and technical and tactical profiles, prefer Sutemi-waza—Ma-sutemi-waza (S-G, T-N), and are oriented toward increased activity in Ne-waza.

The above recommendations were largely formulated by deduction and are derived from athlete and coaching experience. Therefore, they require confirmation based on scientific premises, thus revealing new horizons for research exploration and training activities.

4.4. Limitations of the Study

The lack of research activities regarding a diagnosis of the relationship with tournament fights means that the results of this study may be limited to some extent. The limitation of the test is the repetition of throws from the Sutemi-waza—Ma-sutemi-waza group (S-G, T-N), which are not necessarily preferred by the athletes. Furthermore, in a sports fight, an athlete often uses several different techniques. Despite strict procedures, differences in body height, center of gravity, and body mass may influence the effectiveness of throws. HR parameters depend on climate (temperature and humidity) and other factors (stress and overtraining). However, in light of the inevitable limitations of our experimental design, the test conditions were well-controlled, the procedures were carried out according to a strict protocol, and the results were scientifically valid. In order to capture the multifaceted clinical context, further research is recommended to expand the diagnostics to include measurements of lactic acid concentration in the blood of participants before and after the application of the test stimulus, and should include comparisons between a real sports bout and simulated sparring. Eventually, future research should take into account the identification of other populations such as the representatives of other grappling combat sports and groups of female athletes.

5. Conclusions

The specificity of movements typical of BJJ fighting in the Gi formula justifies the introduction of tests based on useful takedown techniques for the evaluation of special fitness. The use of the right combination of stimuli in the form of selective throwing techniques, takedown control, and a specialized locomotion method increases the diagnostic value of the test. The classification and course of tasks during the execution of the test reflect the key moments of gaining an advantage over the opponent and are consistent with the nature of combat in this sport. The proposed SBJJFT-TZ test is a selective, accurate, and reliable diagnostic tool that is conducive to a cross-sectional evaluation of the special fitness and performance of BJJ athletes.

Practical Application

The SBJJFT-TZ test proposed in this study can be used for the selection and interpretation of the performance of BJJ athletes as it offers a reliable, relevant, and user-friendly research tool. The recommended test can be used safely and under training-room conditions to comprehensively assess the level of preparation in terms of the special fitness and performance of BJJ athletes. Based on the results obtained with the best athletes, it is possible to set directions of training for less successful athletes to improve individual elements of broadly understood special fitness. Due to the similar technical and tactical characteristics of the stand-up fighting plane, it is recommended that the SBJJFT-TZ test be used in other grappling combat sports disciplines where judogi is used.