Back pain and body posture of non-professional Brazilian Jiu-Jitsu practitioners

Participants

The study is observational and involved 61 subjects. The study population consisted of 31 non-professional Brazilian Jiu-Jitsu practitioners, recruited from sports clubs. The control group were 30 subjects-recreational sport practitioners who had never done combat sport. The participants constituted a convenience sample. Each participant was informed about the purpose and procedure of the research, as well as the of possibility of withdrawing at any time during the study. All participants gave their written, informed consent to participate in the project. All experimental protocols were approved. Authors obtained the consent to conduct the study from the Senate Ethics Committee for Scientific Research (SKE 01-45/2016) and confirmed conducting research to the standards set by the Declaration of Helsinki.

The criteria for subject inclusion in the study population were: subject both sexes, age between 18 and 45 years old, having trained BJJ for a minimum of 6 months with the duration of a minimum of 1.5 hours per week, having trained BJJ non-professionally (without participation in competitions and contests). The criteria for subject inclusion in the control group were: age between 18 and 45 years old, different level, being physically active except for training BJJ or any other sports professionally. A sample selection is presented on a flow chart Fig. 1.

The subjects’ age was between 24 and 43 years old (in the study population it was 31.7 ± 5.2 years old, and in the control group it was 29.7 ± 4.4 years old). In each group was 4 women. We did not find statistically significant differences between body mass or body height between the two groups. Table 1 presents the biometric data of the study population subjects.

The mean time of training BJJ in the study population was 3.9 ± 4.1 years. Amount of subject depends on training time presents Table 2. The BJJ practitioners trained a mean of 4.06 ± 2.8 times per week, and the training sessions were 1.5 hours long. Unfortunately, it was not possible divide the BJJ practitioners regarding the fighting style (pass fighters and guard fighters) or an intragroup sub-analysis by practice time because of small number of subjects in particular subgroups.

Postural stability assessment

Postural stability assessment was conducted with the use of the photogrammetric method based on the projection of the moiré method. The equipment for the computer-based body posture assessment system Mora 4th Generation was used. This method is non-invasive, easy to use, easily available, and it is easy to analyse the obtained results. Moreover, the photogrammetric method allows for comparison of results, as it is increasingly often used in postural assessment studies. All the measurements were taken by the same researcher, a physiotherapist (K.S.), trained to operate the equipment while maintaining the constant conditions and procedure of the tests. Before the measurements were conducted a suitable room was adapted for the tests. The tests need to be conducted in a darkened room, so the windows were curtained, and the space in the room was organized properly so as to ensure safe and non-embarrassing conditions for conducting the measurements (the subjects needed to undress for the tests). To calibrate the Mora4G correctly, before each measurement session the device was adjusted using the spirit levels on the front and the side of the device. The researcher measured subjects’ body mass and body height, and then, with the subject standing, marked palpated bony landmarks with a marker pen (spinous processes C7-S1, cervico-thoracic junction, thoracolumbar junction, scapula inferior angles, spina iliaca posterior superior, kyphosis peak, lordosis peak). To ensure comfortable and non-embarrassing conditions, female subjects could use a specially prepared cloth to cover the chest, attached to the body with adhesive tape. Subjects stood with their back to the projector-receiver device at a constant distance of 2.6 m, with their feet placed under their hips and hands along the body, eyes looking forward. Then, the measurement was taken. According to the producer, the measurement error with the MORA 4G system is one cm at a maximum (CQ Elektronik System, 2018). To analyse the photogrammetric measurements, we used the following parameters were used:

Questionnaire

For the purpose of this study, the Polish validated version of the Oswestry Disability Index (ODI) was used (Miekisiak et al., 2013). The ODI is used for the functional state assessment of patients with low back pain and it is the golden standard for the functional assessment in this group of patients. The questionnaire is accessible, patients can complete it on their own and it can be completed in a few minutes. The subjects also filled out the author’s original questionnaire consisting of 8 questions which comprised of the following: the biometric data (age, body mass, sex), data on the subjects’ physical activity (duration, intensity, type), and injuries subjects sustained as well as spinal pain (location, symptoms, causes, pain intensity etc.).

Statistical analysis

Statistical analysis of the collected data was conducted with the STATISTICA 13 programme (TIBCO Software Inc., Palo Alto, CA, USA). Quantitative data was presented in the form of descriptive statistics using such measurements as arithmetic mean and standard deviation. The relationships between qualitative data were assessed with the chi-squared test, and the differences in two groups in quantitative data were assessed with the Mann-Whitney U-test. The non-parametric test was chosen as there was lack of normal distribution in the analysed variables. Normal distribution was verified with the Shapiro-Wilk test. Statistical significance was set at p < 0.05. Effect sizes were computed using method proposed by Tomczak & Tomczak (2014).

Back pain and analysis of sustained injuries

Current back pain was present in 37 subjects (60.7%), including 22 (71.0%) BJJ practitioners and 15 (50.0%) controls (p = 0.094). The pain usually affected the lumbar spine (44.3%), and it was less common in cervical spine (13.1%) and thoracic spine (18.0%). There were no differences in pain topography between the two groups, p >0.05. Pain intensity on the Numeric Rating Scale, NRS (from “0” meaning no pain to “10” meaning pain as bad as you can imagine) was 4.09 ± 1.95 points in the study population and 3.4 ± 1.59 point in the control group and it was statistically insignificant, p = 0.3.

The subjects’ disability was between minimal and moderate as shown by the ODI, and their results did not show statistically significant differences (215% for the studied population, n = 22; 20% for the control group, n = 15).

The most commonly reported injuries by study population subjects sustained because of BJJ training affected the knee (32.3%), the auricle and the ankle (29.0% each), and the elbow (16.1%).

There were no statistically significant differences between the groups in physical activity (p = 0.654). In the study population, 28 subjects (90.3%) declared physical activity beside BJJ, with 26 subjects (86.7%) in the control group. Training of other sports (beside BJJ) was done by subjects from both groups. BJJ practitioners had other physical activity (beside BJJ) statistically significantly less often than the controls (p = 0.027). The study population did it at a mean of 3.89 ± 3.16 times per week, and the control group 5.73 ± 3.47 times per week. Other forms of physical activity of subjects from both groups included power workout (50.8%), stretching (32.8%), swimming (29.5%), running (24.6%) and cycling (19.7%). Subject from control group went swimming statistically significantly more often than the study population subjects (p = 0.004).

Body posture analysis

We observed statistical differences between the two groups in the values of four of the studied parameters: DCK- spinal height, p = 0.001, RKP- kyphosis height calculated between C7 and thoracolumbar junction, p = 0.010, RLL- lordosis height calculated from S1 to the thoracolumbar junction, p = 0.009 and KNM- angle of pelvis inclination, p = 0.041. For each of these four parameters, the study population subjects had higher values than controls. Moreover, the BETA parameter—thoracolumbar region angle and the TT parameter—difference in the height of the waist triangles had lower values in the study population. These values were close to the statistical significance, p = 0.063 and p = 0.056, respectively. Table 3. presents studied parameters value.

The relationship between back pain and postural disorders assessed as a difference in body posture in BJJ practitioners with and without back pain and comparison their photogrammetry parameters with control group. Statistically significant differences between subjects training BJJ with and without back pain from the study population in the RKP - the length of the thoracic kyphosis were found. The RKP parameter values (BJJ practitioners with pain 317.7 ± 14.7 vs. BJJ practitioners without pain 332.2 ± 11.7) were statistically significantly lower in subjects with pain (p = 0.01; effect size = 0.110). Statistically significant differences between subjects training BJJ shorter than 3 years (n = 18) and longer/or 3 years (n = 13) from the study population in the KKP—thoracic kyphosis angle and in the gamma angle - upper thoracic region inclination. The KKP parameter values (BJJ <3 years 162.74 ± 2.88 vs. BJJ ≥3 years 153.28 ± 16) were statistically significantly lower in subjects longer training internship (p = 0.02; effect size = 0.18). The gamma angle values (BJJ <3 years 10.21 ± 2.73 vs. BJJ ≥3 years 19.58 ± 15.89) were statistically significantly lower in subjects longer training internship (p = 0.02; effect size = 0.17). The mean training time in BJJ practitioners with back pain was 3.5 years, and in BJJ practitioners without back pain 4.7 years. There were no statistically significant differences in values of the studied parameters among the control group subjects with and without pain. The multivariate discriminant analysis confirmed above results (Canonical correlation = 0.731; Wilks’ Lambda = 0.465; p = 0.002). Data does not support the thesis on protective influence of BJJ practice. Odds Ratio computed for actual back pain experience is 1.491, CI _.95 (.93−2.16), so it is only close to significance, for BJJ practitioners. Our study remarks the subclinical effects, detectable in photogrammetric analyses.