Do judokas present differences between upper limbs for the concentric strength of the internal and external rotators of the shoulder?

Abstract

BACKGROUND:

Long-time judo training can lead athletes to develop upper limb asymmetry and shoulder asymmetry during force production, mainly in the action of pulling, pushing, and throwing; that requires higher strength and velocity of the internal and external rotators of the shoulders, which may also result in shoulder injury, or a decrease in judo performance.

OBJECTIVE:

To investigate asymmetries in concentric force of the internal and external shoulder rotators of the dominant and non-dominant upper limbs in high-level judokas at angular velocities of 60, 180, and 300^∘/s.

METHODS:

14 highly trained male judokas (age 24.4 $\pm$ 4.8 yrs.; body mass 87.9 $\pm$ 18.7 kg; height 1.8 $\pm$ 0.1 m). All participants performed 5 attempts of movement concentric internal and external rotation of the shoulder with 3 angular velocities (60^∘/s, 180^∘/s, and 300^∘/s) in an isokinetic dynamometer (Cybex^® Humac Norm Dynamometer CSMI, model 502140). The data were analyzed by independent t-student (discrete analysis) a statistical parametric mapping (SPM) curve (one-dimensional analysis).

RESULTS:

There was no difference in dominant vs. non-dominant for discrete analysis ( $p>$ 0.05). There was no difference in dominant vs. non-dominant for SPM analysis. None of the comparisons surpassed the comparison cut-off (t_crit) for the $t$ -test ( $p>$ 0.05).

CONCLUSIONS:

Based on results, judokas do not present significant asymmetries in concentric force of external or internal shoulder rotators when compared to the dominant vs. the non-dominant upper limb according to discrete and one-dimensional (SPM) analysis.

Keywords

Martial arts biomechanics athletic performance task performance and analysis statistical parametric mapping

1. Introduction

Due to the high competitiveness at an international level, judokas train approximately 4 hours a day in activities that demand physical and technical capacity [1]. Training continuity can lead athletes to develop strength and anthropometric asymmetry due to the repetitive application of preferred techniques (tokui-waza) [2]. These asymmetries must be monitored and judokas need to perform compensatory training if necessary because a higher inter-limb difference increases the risk of injury [3, 4]. According to Clark [5], assessing strength asymmetry is a fundamental point for a sports career, as it will prevent the athlete from developing muscular disorders. It is suggested that athletes who present inter-limb asymmetry $\geqslant$ 15% have a lower performance capacity [6] and an increased injury risk [7].

Since the development of asymmetries is inherent in judo training [2, 8], studies have been conducted to measure strength asymmetry in upper [9, 10] and lower limbs [3, 8]. In this line, a study showed that a fatigue protocol resulted in inter-limb asymmetry [8], however, four simulated combats did not produce asymmetry in national level judokas [10]. Therefore, it becomes relevant that new protocols investigate the asymmetries produced by training and its effects on performance and risk of injury.

Specifically in judo, there is a high prevalence of shoulder injuries [11], which are associated with the actions of pulling, pushing and throws [10], especially by the application of arm levee throws [12]. Arm throws (te-waza), such as ippon-seoi-nage and morote-seoi-nage, are often used by competitors [13]. These throws require higher strength and velocity capacity of the internal and external rotators of the shoulders. In order to apply this technique, the tori (athlete executing the throw) must externally rotate and abduct their arm to around a 90-degree angle relative to their thorax. This movement helps to create the necessary space for the opponent to be lifted onto the back. Following this, the tori rapidly internally rotate their arm, which helps to drive the opponent over their shoulder and onto their back [14]. In this context, the importance of assessing the strength of the external and internal shoulder rotators is justified.

In fact, there are already published papers on this subject. Marcondes et al. [15] observed that, regardless of sex, the dominant side tends to present higher glenohumeral rotator muscle strength. Madaleno et al. [16] observed that women tend to have higher shoulder joint laxity than males. In a recent study, Delorme et al. [4] observed that younger athletes have less shoulder stability and higher glenohumeral strength (internal and external) when compared to older judokas. Therefore, it is clear that there are many gaps that have not yet been scientifically explored, and new studies which characterize shoulder action can help in developing specific programs that help to prevent injuries.

Specifically regarding the assessment of internal and external shoulder rotators, studies have used different angular velocities between 0 and 300 degrees/second (^∘/s) to measure the athlete’s ability to generate muscle strength [17]. An isokinetic test at 300^∘/s was applied to handball athletes [18] and baseball pitchers [19] to assess the maximum angular force capacity, 180^∘/s for moderate levels and 60^∘/s for the lowest angular velocity. The isokinetic evaluation is also important for judokas, since the actions developed in combat require the use of dynamic strength, particularly during high velocity and power actions, which can define the winner in the combat [1]. An isokinetic analysis of the rotators can also help to estimate the risk of shoulder injuries and propose prevention strategies [20]. According to data presented by Błach et al. [11], 25% of judokas who injure their shoulder require hospital care and may have their career seriously affected. Furthermore, according to the study carried out by Akoto et al. [21], serious shoulder injuries can take the fighter away from the mats for up to 6 months, and when they return their technical and physical capacity are below ideal.

Most studies using isokinetic force evaluation in shoulder rotators use discrete variables such as peak torque or peak moment to find assessment asymmetric or ratio in judo athletes [22, 23, 24]. However, Roy et al. [25] showed that peak moment could provide a limited view of the changes in shoulder strength due to fatigue, considering that it is specific to judo in its training and competition [26]. However, some studies used statistical parametric mapping (SPM) for biomechanical analysis, and asymmetries [27, 28], because this method enables continuous and complete analysis of the movement, preventing discrete variable selection bias caused by the evaluator [29]. With this analysis strategy, the data obtained from the curve are smoothened, and it is possible to notice space-time changes [22].

In view of the above, the present study aimed to investigate asymmetries in concentric force of the internal and external shoulder rotators of the dominant and non-dominant upper limbs in high-level judokas (without injury or history of shoulder injury), at angular velocities of 60^∘/s, 180^∘/s and 300^∘/s. We hypothesize that the asymmetry presented will be lower than 15%, regardless of velocity.

2. Methods

2.1 Experimental approach

This experimental protocol aimed to measure possible asymmetries of internal and external shoulder rotators in high-performance judokas. The main investigator initially contacted the National Federation to request access to coaches and athletes. An informative speech with the athletes who met the inclusion criteria was given at each club visited, and those who agreed to participate signed the informed consent form in accordance with the Declaration of Helsinki for ethics in scientific studies. Data collection was performed in a single visit to the Neuromechanics laboratory. The participants initially completed an anamnesis in which data on age, dominance side, injury history, and tokui-waza were collected. This protocol was authorized by the institutional ethics committee of the University of Santiago of Chile on July 21, 2013, where the data were collected (Ethics Committee Protocol No. 352/22).

2.2 Participants

The following inclusion criteria were adopted: a) male athletes; b) $\geqslant$ 18 and $\leqslant$ 35 years old; c) without injuries to the upper limbs in the last 6 months; d) be training for competitions ( $\geqslant$ 3/week); and e) $\geqslant$ 3 years of experience in national or international competitions. Athletes that: a) did not complete all the data collection; b) there were errors during the data collection or process; c) did not correctly execute the velocity of the tests; or d) wished to withdraw, were excluded. The sample size calculation was based on a previous study with judokas that measured the asymmetry of rotators in the upper limbs [15]. The asymmetry of internal rotators was considered the main variable for the sample size estimative. Alpha significance levels of 0.05, two-tailed targeting, 95% confidence interval (95% CI), with a power of 0.5 and effect size of 0.2 were adopted. A minimum sample of 12 participants was estimated to achieve a difference of 6.0 N/m between the dominant and non-dominant upper limb; in addition, 2 participants were added considering a possible replacement of 14% (if necessary). Therefore, the final sample of the present study consisted of 14 judokas [age $=$ 24.4 $\pm$ 4.8 yrs.; body mass $=$ 87.9 $\pm$ 18.7 kg; height $=$ 1.8 $\pm$ 0.1 m, BMI $=$ 27.9 $\pm$ 4.1 kg/m²; right biceps circumference $=$ 35.7 $\pm$ 3.3 cm; left biceps circumference $=$ 35.5 $\pm$ 3.2 cm, right thigh circumference $=$ 60.3 $\pm$ 5.7 cm; left thigh circumference $=$ 59.5 $\pm$ 5.9 cm; APE (length of arm span compared to height) index $=$ 182.6 $\pm$ 7.6 cm]. All participants trained about 4 h/day (2 hours in physical fitness and 2 in specific judo training). Moreover, 5 to 6 sessions/wk were performed for the physical training, which included sprints, strength, and power exercises for upper and lower limbs. The specific training consisted of 4 trainings/wk, with all out uchi-komi, tokui-waza, combined techniques and Randori (standing and ground fighting) Performed. Table 1 shows the favorite throw (Tokui waza) technique applied by dominant and non-dominant side.

Table 1
Individual Tokui waza (favorite technique) applied to dominant and non-dominant side by the participants

Participant	Dominance	1st tokui-waza	2nd tokui-waza	3rd tokui-waza
1	Right	Seoi-nage (te-waza) One-armed shoulder throw	Sode-tsuri-komi-goshi (te-waza)	Sumi-gaeshi (sutemi-waza) Corner throw
2	Right	O-goshi (koshi-waza) Large hip throw (hip-technique)	O-goshi (koshi-waza)	Uchi-mata (ashi-waza) Inner thigh reaping throw
3	Right	Harai-goshi (koshi-waza) Hip sweep	Koshi-guruma (koshi-waza) Hip Wheel	Ko-soto-makikomi (sutemi-waza) Small outer wraparound throw
4	Right	Seoi-nage (te-waza)	Uchi-mata (ashi-waza)	Ko-uchi-gari (ashi-waza) Small inner reaps
5	Right	Uchi-mata (ashi-waza)	O-goshi (koshi-waza)	Ko-soto-gake (ashi-waza) Small outer hook
6	Right	Seoi-nage (te-waza)	O-uchi-gari (ashi-waza) Large inner reap	Kata-otoshi (sutemi-waza) Shoulder Drop
7	Right	Harai-goshi (koshi-waza)	Ko-soto-gake (ashi-waza)	Harai-goshi (koshi-waza)
8	Left	Uchi-mata (ashi-waza)	O-soto-gari (ashi-waza) Larger Outer Reap	Sumi-gaeshi (sutemi-waza)
9	Right	Uchi-mata (ashi-waza)	Sumi-gaeshi (sutemi-waza)	O-soto-gari (ashi-waza)
10	Left	Tai-otoshi (te-waza)	Kata-otoshi (sutemi-waza)	Okuriashi harai (ashi-waza)
11	Right	Tai-otoshi (te-waza) Hand throw body drop	Uchi-mata (ashi-waza)	Ko-uchi-gari (ashi-waza)
12	Left	Uchi-mata (ashi-waza)	O-uchi-gari (ashi-waza)	Tani-otoshi (sutemi-waza) Valley drop
13	Left	Sasae-tsurikomi-ashi (ashi-waza) Propping drawing ankle	Ko-uchi-gari (ashi-waza)	Harai-goshi (koshi-waza)
14	Right	Tai-otoshi (te-waza)	Ura-nage (sutemi-waza) Rear throw	Kata-otoshi (sutemi-waza)

Notes: gris cells represent the tokui-waza applied by non-dominant side. Te-waza – throw techniques in which the main lever is applied with the upper limbs, koshi-waza – throw techniques in which the main lever is applied with the trunk, ashi-waza – throw techniques in which the main lever is applied with the lower limbs, sutemi-waza – sacrifice techniques (need a wrapping by the tori).

2.3 Tests

Before each participant entered the laboratory, their temperature was measured, and all the necessary precautions were taken to attend to the COVID protocol of the University. All the participants received the protocol instructions, that there were two tests and the necessary positioning on the machine. Height, body mass, corrected biceps circumference, corrected thigh circumference and APE index were measured before starting the non-isokinetic test. Next, a 15-minute warm-up was performed, which was composed of aerobic exercises on the treadmill, joint mobility and dynamic stretching of the upper limb and trunk, strength of the upper limbs and uchikomi with an elastic band (Morote-seoi-nage).

We evaluated the absolute peak moment normalized by body mass, measured in the internal and external shoulder rotation. The movement was performed in a sitting position with the abductor arm at 45^∘ oriented in the scapular plane, at 3 angular velocities (60^∘/s, 180^∘/s and 300^∘/s), at a sampling frequency of 100 Hz, in concentric/concentric mode, based on the velocity found in throw techniques according to Imamura et al. [30]. Peak moment (Nm) and range of motion (in degrees) were recorded. All evaluations started with the dominant upper limb. All movements were performed within the amplitude limit (70^∘ of internal and external rotation). For each test, the participant was positioned aligning the joint with the mechanical axis of the isokinetic device (Cybex^® Humac Norm Dynamometer CSMI, model 502140, Stoughton, MA, USA). All participants performed 3 submaximal repetitions for familiarization. Then, 5 maximum repetitions were performed together with a standardized verbal stimulus, with a 2-minute rest interval between the dominant and non-dominant arms, while for the different velocities, the participants rested 6-min between them [31], the order of tests was external rotation and external rotation how one-cycle completed five cycles. The subjects were sat with their shoulders abducted 30^∘ and their elbow flexed to 90^∘. The isokinetic device was calibrated before each test according to the operating manual [32], and all measures were performed by the same evaluator. In this study gravity correction was used for all test [33]. The results were calculated as the mean of the five maximum repetitions to moment for each velocity (60^∘/s, 180^∘/s, and 300^∘/s). We used the asymmetry index equation to estimate the risk of injury associated with upper limb asymmetry, as follows: $\text{AI ({\%})}=[(\text{A}-\text{B})/(\text{A}+\text{B})]\times 100;$ in which: AI $=$ asymmetry index; A $=$ dominant limb; B $=$ non-dominant limb, according the recommendations by Parkinson et al. [34].

2.4 Data processing

The signal was extracted from the isokinetic device to a spreadsheet. The first point $>$ 1 Nm was considered the start of movement [35]. The test signal at 300^∘/s analyzed the first 31 data points; then, the first 41 data points at 180^∘/s; and the first 101 data points at 60^∘/s. The valid attempts were averaged for the posterior analysis. Raw data and data normalized by body mass were analyzed. The signals were not filtered.

Table 2
Descriptive values and inferential discrete analyses for internal and external rotation when comparing dominant vs. non-dominant upper limb

Data	Dominant		Non-dominant		AI	Statistic
	M	$\pm$ SD	M	$\pm$ SD	$\Delta$ %	$p$
Raw (Nm)
Internal rotation
60^∘/s	65.5	10.5	62.2	11.9	2.5	0.45
180^∘/s	51.4	12.4	52.7	11.2	$-$ 1.3	0.769
300^∘/s	44.3	10.9	44.1	12.5	0.2	0.965
External rotation
60^∘/s	32.0	7.94	29.4	5.46	4.4	0.308
180^∘/s	23.9	6.68	22.5	5.13	2.9	0.557
300^∘/s	19.9	4.41	19	4.83	2.3	0.607
Normalized (Nm/kg)
Internal rotation
60^∘/s	0.77	0.16	0.73	0.17	2.7	0.547
180^∘/s	0.59	0.12	0.60	0.09	$-$ 0.8	0.756
300^∘/s	0.51	0.08	0.50	0.1	1.0	0.919
External rotation
60^∘/s	0.37	0.08	0.34	0.06	4.2	0.283
180^∘/s	0.28	0.07	0.26	0.04	3.7	0.467
300^∘/s	0.23	0.05	0.22	0.04	2.2	0.437

M $=$ mean; SD $=$ standard deviation; AI $=$ asymmetric index.

2.5 Statistical analysis

A discrete and one-dimensional analyses were performed in the evaluation of asymmetries between the dominant and not-dominant limbs. The discrete analysis was performed between peak moment between limbs through an independent sample Student’s $t$ -test, in which an assumption of equal variance (homogeneity) was confirmed with Levene’s Test ( $p>$ 0.05), using the SPSS version 25 software program. The one-dimensional analyses was performed with SPM (independent $t$ -test) according the procedures described by Pataky [29], in MATLAB^® R2021a program (Mathworks Inc., Natwick, WY, USA) with $+$ spm1d package. This method has the advantage of analyzing the entire curve of moment without the bias of focus in one temporal point (i.e., peak moment) [29, 36]. An alpha level of 0.05 was established for both tests.

3. Results

Table 2 shows the raw and normalized data for the internal (60^∘/s, 180^∘/s and 300^∘/s) and external (60^∘/s, 180^∘/s and 300^∘/s) rotators for dominant and non-dominant upper limb and AI.

3.1 Discrete analysis

There was no difference in dominant vs. non-dominant for discrete analysis ( $p>$ 0.05) (Table 2).

Figure 1.

Statistical parametric mapping (SPM) for difference ( $\Delta)$ between dominant (D) and non-dominant (ND) side for raw (1A and 1B) and normalized internal rotator (IR) and external rotator (ER) concentric force (1C and 1D) over time for a velocity of 60^∘/s. None of the comparisons surpassed ( $p>$ 0.05) the critical $t$ value (t_crit). $t=$ $t$ value.

Figure 2.

Statistical parametric mapping (SPM) for difference ( $\Delta)$ between dominant (D) and non-dominant (ND) side for raw (1A and 1B) and normalized internal rotator (IR) and external rotator (ER) concentric force (1C and 1D) over time for a velocity of 180^∘/s. None of the comparisons surpassed ( $p>$ 0.05) the critical $t$ value (t_crit). $t=$ $t$ -value.

Figure 3.

Statistical parametric mapping (SPM) for difference ( $\Delta)$ between dominant (D) and non-dominant (ND) side for raw (1A and 1B) and normalized internal rotator (IR) and external rotator (ER) concentric force (1C and 1D) over time for a velocity of 300^∘/s. None of the comparisons surpassed ( $p>$ 0.05) the critical $t$ value (t_crit). $t=$ $t$ -value.

3.2 One-dimensional analysis

Figures 1, 2 and 3 show the comparative data through the $t$ -value for the whole moment curve between dominant (D) and non-dominant (ND) upper limbs for the raw and normalized internal (IR) and external (ER) rotator force for the 60^∘/s (Fig. 1), 180^∘/s (Fig. 2), and 300^∘/s (Fig. 3) angular velocities. There was no difference in dominant vs. non-dominant for SPM analysis for none of the angular velocities in internal and external rotation because none of the comparisons surpassed the comparison cut-off (t_crit) for the $t$ -test ( $p>$ 0.05) visualized in the figures.

4. Discussion

Evaluating shoulder internal and external rotator force can be a good predictor of injury risk in athletes [20]. In this sense, this study investigated asymmetries in concentric force of the internal and external shoulder rotators of the dominant and non-dominant upper limbs in high level judokas, at angular velocities of 60, 180 and 300^∘/s. Our main results confirmed our hypothesis, as we did not observe significant asymmetry between dominant vs non-dominant upper limbs despite the angular velocity. Regardless of the statistical result, the AI between the dominant and non-dominant sides did not exceed 5% difference; according to Parkinson et al. [34], the threshold between 10–15% is commonly used as an indicator for the increased risk of injuries, however this value does not yet have scientific support.

Some explanations could be found in the muscles that make up the two groups of shoulder rotators, where the IR muscles are the subscapularis, pectoralis major, and latissimus dorsi, while the ER muscles are composed of the infraspinatus, teres minor, and teres major [37]. The IR muscles are large muscles with multiple movements and more strength than the ER muscles [38]. Although our results did not show statistically significant differences, it is observed that as the speed of execution of the test increases, the differences were smaller, whereas some studies showed that if the speed is not specific to the sport, the peak moment asymmetries will be smaller [39]. On the other hand, the subjects in our study performed physical training for 2 hours a day with emphasis on unilateral and bilateral strength training, where some studies demonstrated that these training present similar improvements in muscle [40], circumference [41] and cross-section area [42],where unilateral strength training enhances specific unilateral strength gains [41] and unilateral strength patterns [43] as a unilateral test.

To the best of our knowledge, the present study was the first to compare the force asymmetry of the internal and external shoulder rotators in high-performance judokas at 3 different angular velocities, and it was also the first study to use the SPM method for analysis. The results of the present study are in line with those obtained by Kons et al. [10], who did not observe an increase in asymmetry in the upper limbs after 4 simulated judo matches (4 min $\times$ 15 interval); however, the asymmetry was measured by handgrip strength (dynamometry). In a protocol similar to our study, Marcondes et al. [15] observed asymmetry $\leqslant$ 10% at velocities of 60^∘/s and 180^∘/s in athletes from the Brazilian judo team.

We found more studies in our literature search which investigated the lower limb asymmetry in judokas [3, 8, 10]. However, the asymmetry of the upper limbs can increase the risk of injuries in the sport [4]. In addition, early detection of asymmetries are important for the development of prevention strategies [44]. One of the factors that can lead to asymmetry in judokas is the successive training of unilaterally applied techniques [16, 45]. It is important to emphasize that relevant asymmetries in the upper limbs have been observed in judokas still in training [2, 45]. In athletes aged 8–18 years, Fukuda et al. [2] observed that training time is directly related to peak ( $r=$ 0.522) and mean ( $r=$ 0.68) handgrip asymmetry. However, this does not seem to be a tendency observed in high-performance adult judokas, as shown by Marcondes et al. [15] and our results. A possible explanation for the lower asymmetry is associated to bilateral training to achieve high-level competitive success [46]. As shown in Table 1, 6 (43%) of the athletes in the present study train their favorite techniques for both sides or have at least one technique for the non-dominant side (because they are at international level).

To the best of our knowledge, this was the first study to measure the force of the internal and external shoulder rotators in judokas by the SPM curve; one of the advantages of this method is to increase the number of observations, allowing a complete analysis of the performed movement [47], as seen in Figs 1–3. SPM is a statistical technique that is widely used in functional neuroimaging to detect spatiotemporal changes in the brain in relation to different experimental conditions [29]. However, recent studies have used this method to analyze performance in sports biomechanics [47, 48, 49]. Using an SPM Curve, James et al. [49] observed that high-level mixed martial arts athletes ( $>$ 50% wins) have a higher power and shorter time during the eccentric phase of CMJ when compared to lower-level.

Based on our results, SPM curves are not sensitive to detect asymmetries in upper limbs of high-performance judokas. Thus, our results raise two hypotheses, namely that either the analyzed group does not have significant asymmetries, or the method is not sensitive for such a diagnosis. When analyzing the tokui-waza (Table 1), approximately 10% of the throws were te-waza to the detriment of 43% of ashi-waza; therefore, the group of analyzed judokas does not preferentially use upper limb levers during training and competitions, which may be a contributing factor for not observing asymmetries. Future studies may perform an individual analysis to obtain such answers [50]. The data obtained in the present study must be interpreted regarding its limitations, since we measured high-performance male athletes without any history of shoulder injuries.

5. Conclusions

Based on the established aims, applied methods, and obtained results, it can be concluded that healthy judokas do not present significant asymmetries in concentric force of external or internal shoulder rotators when compared the dominant vs. the non-dominant upper limb according discrete and one-dimensional (SPM) analysis. Researchers and practitioners should analyze asymmetries individually, because analysis in a group could be influenced between subjects and not be sensible for asymmetries detection.

The asymmetry data observed here may be different for those who trained with higher emphasis on the dominant side. In this sense, we recommend an individualized analysis as practical applications and athletes who present asymmetry above 15% of the internal and external rotators of the shoulder should undergo preventive treatments before injuries occur. Finally, it is important to highlight that this has no history of injury, athletes who were injured may present different results compared to those analyzed here.

Author contributions

CONCEPTION: EAM, DAT, MGV, CJB, BM, ON, PMM and CJB.

PERFORMANCE OF WORK: EAM, DAT, MGV and CJB.

ANALYSIS OF DATA: EAM, DAT, MGV, CJB, PMM, ON and BM.

PREPARATION OF THE MANUSCRIPT: EAM, DAT, MGV, CJB, PMM, ON and BM.

Ethical considerations

The study was authorized by the institutional ethics committee of the University of Santiago of Chile on July 21, 2013, where the data were collected (Ethics Committee Protocol No. 352/22). Participants signed an informed consent form in accordance with the Declaration of Helsinki for ethics in scientific studies.

Funding

This study was partly financed by The Directorate of Scientific and Technologic Research (DICYT) of the University of Santiago of Chile (USACH) under Grant number [022287AM].

Footnotes

Acknowledgments

The authors would like to thank the Chilean judo federation, coaches and athletes.

Conflict of interest

The authors declare no conflict of interest.

References

Franchini

Brito

Fukuda

Artioli

. The physiology of judo-specific training modalities. J Strength Cond Res. 2014; 28(5): 1474-81.

Fukuda

Beyer

Boone

Wang

La Monica

Wells

, et al. Developmental associations with muscle morphology, physical performance, and asymmetry in youth judo athletes. Sport Sci Health. 2018; 14: 555-62.

Stradijot

Pittorru

Pinna

. The functional evaluation of lower limb symmetry in a group of young elite judo and wrestling athletes. Isokinetics Exerc Sci. 2012; 20(1): 13-6.

Delorme

Blache

Degot

Rogowski

. Factors affecting the shoulder functional profile in elite judo athletes. Euro J Sport Sci. 2023; 23(5): 676-83.

Clark

. Functional performance testing following knee ligament injury. Phys Ther Sport. 2001; 2(2): 91-105.

Bishop

Read

Stern

Turner

. Effects of soccer match-play on unilateral jumping and interlimb asymmetry: A repeated-measures design. J Strength Cond Res. 2022; 36(1): 193-200.

Bishop

Turner

Read

. Effects of inter-limb asymmetries on physical and sports performance: A systematic review. J Sports Sci. 2018; 36(10): 1135-44.

Kons

Orssatto

LBdR

Sakugawa

da Silva Junior

Diefenthaeler

Detanico

. Effects of stretch-shortening cycle fatigue protocol on lower limb asymmetry and muscle soreness in judo athletes. Sports Biomech. 2020; 1-16.

Kons

Orssatto

Detanico

. Acute performance responses during repeated matches in combat sports: A systematic review. J Sci Med Sport. 2020; 23(5): 512-8.

10.

Kons

Dal Pupo

Gheller

Costa

Rodrigues

Bishop

, et al. Effects of successive judo matches on interlimb asymmetry and bilateral deficit. Phys Ther Sport. 2021; 47: 15-22.

11.

Błach

Smolders

Rydzik

Bikos

Maffulli

Malliaropoulos

, et al. Judo injuries frequency in Europe’s top-level competitions in the period 2005–2020. J Clin Med. 2021; 10(4): 852.

12.

Blais

Trilles

Lacouture

. Three-dimensional joint dynamics and energy expenditure during the execution of a judo throwing technique (Morote Seoi Nage). J Sports Sci. 2007; 25(11): 1211-20.

13.

Pereira Martins

Dualiby Pinto de Souza

Pinheiro de Campos

Bromley

Yuri Takito

Franchini

. Techniques utilised at 2017 Judo World Championship and their classification: comparisons between sexes, weight categories, winners and non-winners. Ido Mov Cult J Martial Arts Anthropol. 2019; 19(1): 58-65.

14.

Green

Comfort

Herrington

. Shoulder joint position sense in injured and noninjured judo athletes. Int J Athl Ther Train. 2013; 18(2): 29-33.

15.

Marcondes

Castropil

Schor

Miana

Vasconcelos

Etchebehere

. Shoulder isokinetic performance in healthy professional judo athletes: Normative data. Acta Ortop Bras. 2019; 27: 308-12.

16.

Madaleno

Verhagen

Ferreira

Ribeiro

Ocarino

Resende

. Normative reference values for handgrip strength, shoulder and ankle range of motion and upper-limb and lower limb stability for 137 youth judokas of both sexes. J Sci Med Sport. 2021; 24(1): 41-5.

17.

Park

J-H

Chung

Lee

S-J

Lee

J-W

K-S

. Evaluation of the electromyographic amplitude-to-work ratio in the infraspinatus muscle during external shoulder rotation exercises: a comparison of concentric isotonic and isokinetic exercises. Orthop J Sports Med. 2020; 8(7): 2325967120932459.

18.

Zapartidis

Gouvali

Bayios

Boudolos

. Throwing effectiveness and rotational strength of the shoulder in team handball. J Sports Med Phys Fit. 2007; 47(2): 169.

19.

Carter

Kaminski

Douex Jr

Knight

Richards

. Effects of high volume upper extremity plyometric training on throwing velocity and functional strength ratios of the shoulder rotators in collegiate baseball players. J Strength Cond Res. 2007; 21(1): 208-15.

20.

Bagordo

Ciletti

Kemp-Smith

Simas

Climstein

Furness

. Isokinetic dynamometry as a tool to predict shoulder injury in an overhead athlete population: a systematic review. Sports. 2020; 8(9): 124.

21.

Akoto

Lambert

Balke

Bouillon

Frosch

K-H

Höher

. Epidemiology of injuries in judo: a cross-sectional survey of severe injuries based on time loss and reduction in sporting level. Br J Sports Med. 2018; 52(17): 1109-15.

22.

Macak

Drapsin

Atanasov

Trajkovic

Trivic

Vukovic

, et al. Isokinetic performance of shoulder external and internal rotators in judo and karate elite male athletes. Gazzetta Medica Italiana-Archivio per le Scienze Mediche. 2021; 180(12): 836-41.

23.

Detanico

Ghedini Gheller

Saldanha Da Silva Athayde

Lima Kons

. Shoulder rotator strength in judo athletes: A cross-sectional study with different experience levels. Isokinetics and Exercise Science. 2022(Preprint): 1-7.

24.

Vargas

Motta

Vancini

de Lira

CAB

Andrade

. Shoulder isokinetic strength balance ratio in overhead athletes: a cross-sectional study. International Journal of Sports Physical Therapy. 2021; 16(3): 827.

25.

Roy

J-S

MacDermid

Woodhouse

. Shoulder muscle endurance: the development of a standardized and reliable protocol. Sports Medicine, Arthroscopy, Rehabilitation, Therapy & Technology. 2011; 3(1): 1-14.

26.

Kons

Dal Pupo

Ache-Dias

Garcia

da Silva

Katicips

LFG

, et al. Effect of official judo matches on handgrip strength and perceptual responses. Journal of Exercise Rehabilitation. 2018; 14(1): 93.

27.

Vieira

Rodrigues

de Oliveira Assis

de Mendonça Mesquita

Lemes

De Villa

GAG

, et al. Effects of additional load at different heights on gait initiation: A statistical parametric mapping of center of pressure and center of mass behavior. Plos One. 2021; 16(6): e0242892.

28.

Bańkosz

Winiarski

. Statistical parametric mapping reveals subtle gender differences in angular movements in table tennis topspin backhand. International Journal Of Environmental Research And Public Health. 2020; 17(19): 6996.

29.

Pataky

. Generalized n-dimensional biomechanical field analysis using statistical parametric mapping. J Biomech. 2010; 43(10): 1976-82.

30.

Imamura

Iteya

Hreljac

Escamilla

. A kinematic comparison of the judo throw Harai-goshi during competitive and non-competitive conditions. J Sports Sci Med. 2007; 6(CSSI-2): 15.

31.

Parcell

Sawyer

Tricoli

Chinevere

. Minimum rest period for strength recovery during a common isokinetic testing protocol. Medicine & Science in Sports & Exercise. 2002; 34(6): 1018-22.

32.

Habets

Staal

Tijssen

van Cingel

. Intrarater reliability of the Humac NORM isokinetic dynamometer for strength measurements of the knee and shoulder muscles. BMC Research Notes. 2018; 11(1): 1-5.

33.

Perrin

Hellwig

Tis

Shenk

. Effect of gravity correction on shoulder rotation isokinetic average force and reciprocal muscle group ratios. Isokinetics and Exercise Science. 1992; 2(1): 30-3.

34.

Parkinson

Apps

Morris

Barnett

Lewis

. The calculation, thresholds and reporting of inter-limb strength asymmetry: A systematic review. J Sports Sci Med. 2021; 20(4): 594.

35.

Cossich

Gavilão

Goes

Perini

Laett

Maffiuletti

. Maximal vs. explosive knee extensor strength in professional soccer players: inter-limb asymmetries and relationship with knee function. Euro J Sport Sci. 2022; 1-8.

36.

Pataky

Robinson

Vanrenterghem

. Vector field statistical analysis of kinematic and force trajectories. J Biomech. 2013; 46(14): 2394-401.

37.

Kapandji

Honoré

. The physiology of the joints, volume 1: upper limb., translator. London: E. & S. Livingstone. 1970.

38.

Kim

D-K

Park

Kuo

L-T

Park

W-H

. Isokinetic performance of shoulder external and internal rotators of professional volleyball athletes by different positions. Scientific Reports. 2020; 10(1): 8706.

39.

Madeira

Nobre

Costa

Almeida

Paulo Sousa

Pereira

ÂM

. Isokinetic profile of the shoulder internal and external rotators in surfers. Annals of Medicine. 2019; 51(sup1): 218.

40.

Janzen

Chilibeck

Davison

. The effect of unilateral and bilateral strength training on the bilateral deficit and lean tissue mass in post-menopausal women. European Journal of Applied Physiology. 2006; 97: 253-60.

41.

Botton

Radaelli

Wilhelm

Rech

Brown

Pinto

. Neuromuscular adaptations to unilateral vs. bilateral strength training in women. Journal of Strength and Conditioning Research. 2016; 30(7): 1924-32.

42.

Häkkinen

Kallinen

Linnamo

Pastinen

Newton

Kraemer

. Neuromuscular adaptations during bilateral versus unilateral strength training in middle-aged and elderly men and women. Acta Physiologica Scandinavica. 1996; 158(1): 77-88.

43.

Zhang

Chen

Xie

Ding

, et al. Effect of unilateral training and bilateral training on physical performance: A meta-analysis. Frontiers in Physiology. 2023; 14: 607.

44.

Błach

Rydzik

Stanula

Cynarski

Ambroży

. Injury symmetry in judo. Symmetry. 2023; 15(1): 13.

45.

Mala

Maly

Camilleri

Dornowski

Zahalka

Petr

, et al. Gender differences in strength lateral asymmetries, limbs morphology and body composition in adolescent judo athletes. Arch Budo. 2017.

46.

Šimenko

Hadžić

. Bilateral throw execution in young judokas for a maximum all year round result. Int J Sports Physiol Perform. 2021; 17(5): 720-5.

47.

Hughes

Warmenhoven

Haff

Chapman

Nimphius

. Countermovement jump and squat jump force-time curve analysis in control and fatigue conditions. J Strength Cond Res. 2022; 36(10): 2752-61.

48.

Donegan

Eustace

Morris

Penny

Tallis

. The Keywords: countermovement jump; neuromuscular fatigue; statistical parametric mapping; youth effects of soccer specific exercise on soccer countermovement jump performance in elite youth soccer players. Children. 2022; 9: 1861.

49.

James

Connick

Haff

Kelly

Beckman

. The countermovement jump mechanics of mixed martial arts competitors. J Strength Cond Res. 2020; 34(4): 982-7.

50.

Bishop

Lake

Loturco

Papadopoulos

Turner

Read

. Interlimb asymmetries: The need for an individual approach to data analysis. J Strength Cond Res. 2021; 35(3): 695-701.

Do judokas present differences between upper limbs for the concentric strength of the internal and external rotators of the shoulder?

Abstract

BACKGROUND:

OBJECTIVE:

METHODS:

RESULTS:

CONCLUSIONS:

Keywords

1. Introduction

2. Methods

2.1 Experimental approach

2.2 Participants

Table 1 Individual Tokui waza (favorite technique) applied to dominant and non-dominant side by the participants

2.4 Data processing

Table 2 Descriptive values and inferential discrete analyses for internal and external rotation when comparing dominant vs. non-dominant upper limb

3. Results

3.1 Discrete analysis

4. Discussion

5. Conclusions

Author contributions

Ethical considerations

Funding

Footnotes

Acknowledgments

Conflict of interest

References

Table 1
Individual Tokui waza (favorite technique) applied to dominant and non-dominant side by the participants

Table 2
Descriptive values and inferential discrete analyses for internal and external rotation when comparing dominant vs. non-dominant upper limb