Correction: Muscle strength, muscle power and body composition in college-aged young women and men with Generalized Joint Hypermobility.

[This corrects the article DOI: 10.1371/journal.pone.0236266.].

Muscle strength, muscle power and body composition in college-aged young women and men with Generalized Joint Hypermobility.

The aim of this study was an evaluation of the musculoskeletal system in women and men with Generalized Joint Hypermobility (GJH). The study included 87 participants- 40 with Generalized Joint Hypermobility (aged 21.2 ±1.8 years) and 47 (aged 21.0 ±1.3 years) in the control group (CG). The study included the Beighton score, the measurements of body composition, muscle flexibility (Straight Leg Raise test, Popliteal Angle test, Modified Thomas Test), and the measurements of muscle strength and muscle power. T-test and Mann-Whitney U Test were applied to assess the differences between independent groups. The study showed that there were no significant differences (p>.05) in the assessed body composition and the muscle flexibility between both women and men with GJH and the participants in the CG. Under isokinetic conditions for the non-dominant lower extremity, men from the CG received significantly higher (p = .02) flexion peak torque at 180°/s angular velocity. Women from the CG received a statistically significantly lower (p = .04) F/E ratio at 180°/s velocity. Under isometric conditions for both women and men with GJH, there were no statistically significant differences (p>.05) in the maximum torques in knee extension and flexion compared to the CG. For women and men with GJH, the maximum power in the lower extremities and jumping ability were not significantly different (p>.05) compared to the CG participants. The body composition, muscle flexibility, muscle strength, and muscle power of adults with Generalized Joint Hypermobility did not differ compared to healthy participants. The fact that there are no differences does not exclude the efficacy of strength training in increasing levels of muscle strength and its impact on body posture and proprioception or coordination.

Prevalence of back pain and the knowledge of preventive measures in a cohort of 11619 Polish school-age children and youth-an epidemiological study.

The study sought to characterize back pain (BP) (in the period of 12 months) in children and youth aged 10 to 19 from eastern Poland.The study included 11619 children and youth (6254 girls and 5365 boys) aged 10 to 19 from eastern Poland. An original questionnaire was applied as a research tool. Before the study, the reliability of the questionnaire had been assessed. The Kappa coefficient value for all the analyzed variables was equal to or higher than 0.91.Over 74.4% of the respondents admitted that within the last 12 months, they had experienced BP which was usually located in the lumbar spine (55.8%). The percentage of individuals reporting BP increased with age of participants. Girls reported BP more often than boys (82.8% vs 64.3%). The main circumstances in which BP occurred included lifting heavy objects, carrying school backpack and maintaining a sedentary position (70.7% vs 67.4% vs 67.8%). Over 67% of the respondents declared they did not know ergonomic principles.High prevalence of BP was noted. The declared BP was mainly located in the lumbar spine. Girls reported BP more often than boys. The students presented a very low level of knowledge about ergonomics. Therefore, the appropriate education should be included at school.

The Influence of the "Straighten Your Back" Command on the Sagittal Spinal Curvatures in Children with Generalized Joint Hypermobility.

Objectives. The aim of the study was to assess the change of sagittal spinal curvatures in children with generalized joint hypermobility (GJH) instructed with "straighten your back" command (SYB). Methods. The study included 56 children with GJH. The control group consisted of 193 children. Sacral slope (SS), lumbar lordosis (LL), global thoracic kyphosis (TK), lower thoracic kyphosis (LK), and upper thoracic kyphosis (UK) were assessed with Saunders inclinometer both in spontaneous positions (standing and sitting) and after the SYB. Results. Children with GJH after SYB presented the following: in standing, increase in SS and decrease in TK, LK, and UK (P < 0.01), with LL not significantly changed; in sitting: decrease in global thoracic kyphosis (35.5° (SD 20.5) versus 21.0° (SD 15.5), P < 0.001) below the standards proposed in the literature (30-40°) and flattening of its lower part (P < 0.001). The same changes were observed in the control group. Conclusions. In children with generalized joint hypermobility, the "straighten your back" command leads to excessive reduction of the global thoracic kyphosis and flattening of its lower part. Therefore, the "straighten your back" command should not be used to achieve the optimal standing and sitting positions.

Low Back Pain and Everyday Functioning of Students.

INTRODUCTION: The aim of the study was to determine the frequency of low back pain episodes (over a period of 12 months) and everyday functioning of students suffering from it. MATERIAL AND METHODS: The study enrolled 1321 students of the 1st, 2nd and 3rd year of Bachelor-level programmes in Physical Education, Physiotherapy, Pedagogics, and Tourism and Recreation at 4 universities in Poland. An original questionnaire was used. A 10-point VAS scale was used to assess pain intensity. The reliability of the questionnaire had been assessed before commencing the study by administering it twice at a month's interval to a group of 20 people. No significant differences were noted between the results obtained in the two tests (p<0.05). RESULTS: Our analysis of the frequency of low back pain episodes showed that the respondents who experienced pain rarely (1-2 episodes per year) constituted the biggest group. With regard to pain intensity, mild pain, reported by 43.4% of the respondents, was most common. Over 20% of the subjects reported severe pain. A considerable percentage of the respondents (over 20%) limited their physical activity because of low back pain and 4.4% had to give up physical activity altogether. Nearly 60% of the subjects reported that the low back pain made it difficult for them to sit for prolonged periods, while nearly 50% had difficulty standing. CONCLUSIONS: 1. This study of a group of students from eastern Poland revealed that low back pain is common. 2. Low back pain interferes with or limits daily activities of the students, such as sitting, standing or physical activity.

Intra- and interobserver repeatability of the assessment of anteroposterior curvatures of the spine using Saunders digital inclinometer.

INTRODUCTION: According to the requirements of Evidence Based Medicine, every research tool and method should be subjected to reliability evaluation. A variety of inclinometers are used for the assessment of sagittal plane spinal curvatures in clinical practice. The aim of the study was to evaluate the intra- and interobserver repeatability of measurements of the anterior-posterior spinal curvatures taken with Saunders digital inclinometer. MATERIAL AND METHODS: The study involved 30 healthy subjects (5 males, 25 females) aged 20 to 35 years. The anteroposterior curvatures of the spine were measured in all subjects using a Saunders digital inclinometer. In order to evaluate the intraobserver repeatability of measurements, the results obtained by one investigator were compared. To evaluate interobserver repeatability, the results obtained by three investigators were compared. Additionally, the levels of reliability and measurement error were determined. RESULTS: The measurements conducted by one investigator showed good repeatability for sacral slope, lumbar lordosis, and thoracic kyphosis, including the angle of proximal (Th1-Th6) and distal (Th6-Th12) thoracic kyphosis (p>0.05). For measurements taken by three investigators, interobserver repeatability was achieved for thoracic kyphosis (p>0.05). The reliability of the measurements was good (Cronbach's alpha was 0.9> α ≥0.8), and the measurement error was between 2.8°-3.8°. CONCLUSIONS: The assessment of anteroposterior curvatures of the spine by one investigator provided good repeatability and reliability of measurements. Measurements performed by more than one investigator displayed partial repeatability. The value of the observational error should be taken into account in the interpretation of results of measurements performed with the Saunders inclinometer. The assessment of anteroposterior curvatures of the spine should be preceded by a verification of measurement reliability.