The relationship between the Functional Movement Screen and the Y Balance Test in youth footballers

Background

The Functional Movement Screen (FMS) and the Y Balance Test (Y-BT) are screening tools to detect movement deficits and to identify footballers at high risk of injury. If these tools are able to identify athletes with high risk of injury, they should measure the same construct and also be highly correlated.

Objectives

The aim of the study was to determine the relationship between the FMS and Y-BT in youth footballers. The present study also aimed to assess the degree of association between the FMS and Y-BT considering high-injury-risk (FMS <= 14 points and Y-BT <= 89.6%) and low-injury-risk groups (FMS > 14 points and Y-BT > 89.6%).

Method

A sample of 226 healthy athletes (mean age: 14.0 ± 2.3 years) was selected from a football club. The FMS and Y-BT data were collected from all participants. The Y-BT raw data were normalised to the relative length of the lower limbs. Spearman's correlation was used in the analysis.

Results

For the whole group, there was a moderate correlation (R = 0.41; p < 0.001) between the composite FMS score and composite Y-BT score. The strength of relationships varied from weak to moderate between the FMS subtests and most Y-BT results for each direction. In the high-injury-risk group, there was no correlation (R = 0.11; p = 0.61) between the composite FMS score and composite Y-BT score. For the low-injury-risk group, there was a weak significant correlation (R = 0.27; p < 0.007) between the composite FMS score and composite Y-BT score. Additionally, 56 and 53 athletes were classified to the high-injury-risk group based on the FMS and Y-BT, respectively. Only 23 athletes were classified to the high-risk group by both tests.

Conclusions

Youth footballers showed only weak to moderate correlations between the FMS and the Y-BT. Footballers classified in the high-injury-risk group based on the FMS and Y-BT presented a different relationship between the FMS and Y-BT tasks compared to the low-injury-risk group. The results confirmed that the FMS and Y-BT should not be used interchangeably as they assess different movement deficits in the group of youth football players. The study results may partially suggest that using one of these screening tools cannot successfully predict injury risk in adolescent football players. This justifies the need to use these tests simultaneously to identify possible neuromuscular control deficits in youth footballers.

Shear wave elastography for assessing lateral abdominal muscles in thoracolumbar scoliosis: A preliminary study

BACKGROUND

There are no studies on the scoliotic population in which lateral abdominal muscle (LAM) was measured.

OBJECTIVE

The aim of the study was to deliver the first results on LAM elasticity assessed by shear wave elastography (SWE) in right-side and left-side thoracolumbar scoliosis patients.

METHOD

Twelve patients (mean age 12.25) with thoracolumbar scoliosis were included in the study. Muscle thickness and SWE of the obliquus external (OE), obliquus internal, and transversus abdominis (TrA) were measured with an ultrasound scanner. Measurements were taken at rest and during isometric contraction.

RESULTS

An analysis showed that in right-side scoliosis, the OE muscle on the convex side was stiffer by 7.25 kPa compared to the concave side. The OE muscle on the convex side in right-side scoliosis was also stiffer by 11.6 kPa compared to the convex side in left-side scoliosis. In left-side scoliosis, the TrA muscle on the concave side was stiffer by 7.84 kPa compared to the convex side.

CONCLUSION

Changes in LAM elasticity of thoracolumbar scoliosis were observed. A different pattern of LAM stiffness in different curve directions may be expected. OE and TrA shear moduli are the most sensitive to change in adolescent spinal deformation.

Morphological changes of the lateral abdominal muscles in adolescent soccer players with low back pain: A prospective cohort study

BACKGROUND

Most papers examining the lateral abdominal muscles (LAMs) and low back pain (LBP) are cross-sectional, with groups of participants being divided into a control and an LBP group. We hypothesized that morphological measurements of the LAMs in adolescent soccer players may predict future LBP incidence. The aim of this study was to examine the associations between the morphology of LAMs and LBP incidence rate among adolescent soccer players.

METHODS

Ninety-seven adolescent male soccer players with no LBP at baseline were recruited into the prospective cohort study. The thickness of the LAMs was measured at baseline by ultrasound imaging in a supine rest position. Nine cases of LBP occurred during the follow-up 6-month observation.

RESULTS

An obliquus internus (OI) asymmetry was related to increasing LBP risk (odds ratio = 19.99; 95%CI: 2.4-167.9). Spearman correlation also showed a linear relationship between OI asymmetry value and duration of LBP (R = 0.75, p = 0.02). An OI side-to-side difference greater than 1.25 mm suggests possible LBP incidence in the 6-month observation among adolescent soccer players.

CONCLUSION

The morphological changes of the OI may be related to LBP's incidence in adolescent soccer players. The presence of OI asymmetry increases the odds of LBP by at least 2.4 times. Hypertrophy of the OI on one side of the body may contribute to trunk muscle imbalance.

Long-term patient observation after conservative treatment of carpal tunnel syndrome: a summary of two randomised controlled trials

Background

Physiotherapy of carpal tunnel syndrome (CTS) involves manual therapy based on neurodynamic techniques. Until now, two randomized controlled trials have shown that immediately after therapy, CTS patients who received neurodynamic techniques had significant improvement in nerve conduction, pain, symptom severity (SSS), functional state (FSS), muscle strength (MS) and two-point discrimination (2PD). However, long-term effects seem to be more important, as they are the only ones that can significantly improve the patient's health and influence economic and social costs. Thus, the objective of this study was to evaluate the long-term (six months) effects of neurodynamic techniques in the conservative treatment of CTS patients.

Methods

Carpal tunnel syndrome patients (107) from two previously published randomised clinical trials were observed for six months after the treatment based on neurodynamic techniques.

Results

The sensory conduction velocity, motor conduction velocity, and motor latency were not subject to statistically significant changes within six months after therapy (p > 0.05). In both groups, there was further pain reduction (p < 0.05). In Group B, the symptom severity improved significantly (p < 0.05), while the functional status in both groups remained unchanged (p > 0.05). In both groups, there was muscle strength improvement (p < 0.05). Two-point discrimination remained unchanged six months after the therapy.

Conclusion

The use of manual therapy based on neurodynamic techniques maintains the beneficial effects 6 months after therapy in CTS patients.

Supersonic Shear Imaging for Quantification of Lateral Abdominal Muscle Shear Modulus in Pediatric Population with Scoliosis: A Reliability and Agreement Study

The aim of this study was to assess the intra- and inter-rater reliability/agreement of the lateral abdominal muscle (LAM) stiffness and thickness measurements at rest and during contraction and to determine the relationship between the superficial fat thickness and the LAM stiffness measurements. LAM stiffness and thickness were measured using supersonic shear wave elastography (SSI) in pediatric participants. The reliability of LAM stiffness and thickness measurements ranged from moderate to excellent. There was an inverse correlation between fat thickness and between-rater difference in the resting external oblique stiffness (r > -0.37) and the contracted external and internal oblique stiffness (r > -0.40). SSI is a reliable method for assessing LAM stiffness and thickness in pediatric populations. To remove potential systematic errors: (i) the first round of measurements should be performed to familiarize patients with procedures; (ii) the examiner should pay more attention while performing LAM measurements on the opposite side of the body.

Reliability of the lateral abdominal muscle thickness measurements in idiopathic scoliosis patients

BACKGROUND

To date, the reliability of ultrasound imaging (US) measures of the abdominal muscle thickness in idiopathic scoliosis (IS) patients during early stages of adolescence has not been confirmed.

OBJECTIVE

To assess the intra-rater reliability of US measures of the thickness of the external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) on convex and concave body sides in adolescents with IS.

DESIGN

One-way repeated-measures analysis of variance (ANOVA) and reliability study.

METHODS

Fifteen patients diagnosed IS were included between the ages of 9 and 14 years. Three repeated US measurements were recorded in the supine resting position over 2 sessions, 24 h apart.

RESULTS

By assessing the mean value from the first two measurements (ICC_3,2), the reliability was between .76 and .95 for all examined muscles on the convex and concave sides. The reliability for the mean values from three measurements (ICC_3,3) was between .81 and .96. The smallest detectable difference values for single measurements were twice as high on the convex side than on the concave side for all examined abdominal muscles.

CONCLUSION

US measurements of the thickness of the EO, IO, and TrA muscles in supine rest position in adolescent IS patients are reliable. In order to increase measurement reliability, and due to variability in reliability between concave and convex body side, we recommend using the mean of three consecutive measurements of the EO, IO, and TrA muscles for adolescents with IS.

Is manual therapy based on neurodynamic techniques effective in the treatment of carpal tunnel syndrome? A randomized controlled trial

OBJECTIVE:

The aim of this study was to evaluate the efficacy of manual therapy based on neurodynamic techniques in conservative treatment of carpal tunnel syndrome.

DESIGN:

Randomized controlled trial.

SETTING:

Several medical outpatient clinics in the south of Poland.

PARTICIPANTS:

The study included 103 patients with mild and moderate carpal tunnel syndrome (mean age = 53.95, SD = 9.5) years, who were randomly assigned to a neurodynamic techniques group (experimental group, n = 58) or a group without treatment (control group, n = 45).

INTERVENTION:

Neurodynamic techniques were used in the experimental group. Treatment was conducted twice weekly (20 sessions). Control group did not receive treatment.

MAIN MEASURES:

Nerve conduction study, pain, symptom severity and functional status of Boston Carpal Tunnel Questionnaire, and strength of cylindrical and pincer grips were assessed at baseline and immediately after treatment (nerve conduction study one month after treatment).

RESULTS:

Baseline assessment revealed no group differences in any assessed parameters ( P > 0.05). There were significant differences between groups after treatment, including nerve conduction (e.g. sensory conduction velocity: experimental group: 38.3 m/s, SD = 11.1 vs control group: 25.9 m/s, SD = 7.72, P  < 0.01). Significant changes also occurred in pain (experimental group: 1.38, SD = 1.01 vs control group: 5.46, SD = 1.05, P < 0.01), symptom severity (experimental group: 1.08, SD = 0.46 vs control group: 2.87, SD = 0.68, P < 0.01), and functional status (experimental group: 1.96, SD = 0.64 vs control group: 2.87, SD = 1.12, P < 0.01). There were no group differences in strength ( P > 0.05).

CONCLUSION:

The use of neurodynamic techniques in conservative treatment for mild to moderate forms of carpal tunnel syndrome has significant therapeutic benefits.

Back School programme for nurses has reduced low back pain levels: A randomised controlled trial

AIMS AND OBJECTIVES

(i) To examine patient lifting techniques used by nurses, and (ii) to evaluate an effectiveness of the Spine Care for Nurses programme in chronic nonspecific low back pain syndrome reduction and the execution of proper patient lifting techniques.

BACKGROUND

Millions of nurses around the world suffer from occupational-related chronic nonspecific low back pain (chronic nonspecific low back pain syndrome). Generally, low back pain in nurses is a result of increased pressure on the spine and can be associated with improperly conducted patient lifting techniques.

METHODS

A randomised controlled trial was conducted among 137 nurses with chronic nonspecific low back pain syndrome. Participants were randomised into an experimental and control group (experimental group n = 67, control group n = 70). Nurses in the experimental group attended the Spine Care for Nurses programme for 3 months. The programme consisted of didactic education, spine-strengthening exercises and education on safe patient handling techniques. The control group only received a brief written lifestyle guidance. The Zebris WinSpine Triple Lumbar examination was used to analyse nurses' patient lifting techniques (horizontal and vertical lifting). The lumbar pain intensity was measured with a 0-100 visual analogue scale.

RESULTS

The pre-intervention average chronic nonspecific low back pain syndrome intensity score on visual analogue scale decreased from 49.3 to the postintervention score of 7.5. The correct execution of vertical lifting techniques in the experimental group increased from 8.91%-97.01% (control group: 8.57% pre-intervention test and postintervention test 11.42%). The horizontal patient lifting technique pre-intervention increased from 10.44%-100% correct execution in the experimental group (control group: pre-intervention test 10.00% and postintervention test 11.42%).

CONCLUSION

The Spine Care for Nurses programme significantly reduced chronic nonspecific low back pain syndrome and increased the number of properly executed horizontal and vertical patient lifting techniques in nurses.

RELEVANCE TO CLINICAL PRACTICE

We recommend that healthcare organisations should consider the implementation of regular Spine Care for Nurses programmes as successful low back injury prevention programmes.

Reliability and number of trials of Y Balance Test in adolescent athletes

BACKGROUND

The Star Excursion Balance Test (SEBT) is commonly used to evaluate dynamic equilibrium. The Y Balance Test (Y-BT) is a shortened version of the SEBT where a Y- Balance Kit is commonly used. To date, research concerning the protocol and reliability of the SEBT and Y-BT has been conducted only for adults.

OBJECTIVES

The aim of the study was to assess the protocol (the necessary number of trials to stabilize the results) and reliability of the Y-BT in adolescent athletes.

DESIGN

One-way repeated-measures analysis of variance (ANOVA) and reliability study.

METHOD

The sample of 38 athletes (mean age: 15.6 years) was selected from a football club. A Y-Balance test kit was applied for the evaluation of dynamic balance. The analysis used the values normalized to the relative length of the lower limbs.

RESULTS

After six attempts, three consecutive ones achieved stability for all directions and both extremities (p > 0.05). The intraclass correlation coefficient (ICC_3,1), standard error of measurement and minimal detectable change values for the three attempts ranged from 0.57 to 0.82, from 3 to less than 6% and from 7.68 to 13.7%, respectively.

CONCLUSIONS

In the study of adolescent dynamic equilibrium using the Y-BT, it is recommended to perform nine attempts (including six trial attempts and three measurements). In order to increase reliability it is recommended that the average of the three measured attempts is analysed.

Body Mass Normalization for Lateral Abdominal Muscle Thickness Measurements in Adolescent Athletes

OBJECTIVES

To determine the value of allometric parameters for ultrasound measurements of the oblique external (OE), oblique internal (OI), and transversus abdominis (TrA) muscles in adolescent athletes. The allometric parameter is the slope of the linear regression line between the log-transformed body mass and log-transformed muscle size measurement.

METHODS

The study included 114 male adolescent football players between the ages of 10 and 19 years. All individuals with no surgical procedures performed on the trunk area and who had played a sport for at least 2 years were included. A real-time B-mode ultrasound scanner with a linear array transducer was used to obtain images of the lateral abdominal muscles from both sides of the body. A stabilometric platform was used to assess the body mass value.

RESULTS

The correlations between body mass and the OE, OI, and TrA muscle thicknesses were r = 0.73, r = 0.79, and r = 0.64, respectively (in all cases, P < .0001). The allometric parameters were 0.77 for the OE, 0.67 for the OI, and 0.61 for the TrA. Using these parameters, no significant correlations were found between body mass and the allometric-scaled thickness of the lateral abdominal muscles.

CONCLUSIONS

Significant positive correlations exist between body mass and lateral abdominal muscle thickness in adolescent athletes. Therefore, it is reasonable to advise that the values of the allometric parameters for the OE, OI, and TrA muscles obtained in this study should be used, and the allometric-scaled thicknesses of those muscles should be analyzed in future research on adolescent athletes.

Body Mass Normalization for Ultrasound Measurements of Adolescent Lateral Abdominal Muscle Thickness

OBJECTIVES

The purpose of this study was to determine the value of the allometric parameter for ultrasound measurements of the thickness of the oblique external (OE), internal (OI), and transversus abdominis (TrA) muscles in the adolescent population. The allometric parameter is the slope of the linear regression line between the log transformed body mass and log transformed muscle size measurement.

METHODS

The study included 321 adolescents between the ages of 10 and 17, consisting of 160 boys and 161 girls. The participants were recruited from local schools and attended regular school classes at normal grade levels. All individuals with no signs of scoliosis (screening with use of a scoliometer), and no surgical procedures performed on the trunk area were included. A real-time ultrasound B-scanner with a linear array transducer was used to obtain images of the lateral abdominal muscles from both sides of the body.

RESULTS

The correlation between body mass and the OE muscle was r = 0.69; the OI muscle r = 0.68; and the TrA muscle r = 0.53 (in all cases, P < .0001). The allometric parameter for the OE was 0.88296; the OI 0.718756; and the TrA 0.60986. Using these parameters, no significant correlations were found between body mass and the allometric-scaled thickness of the lateral abdominal muscles.

CONCLUSIONS

Significant positive correlations exist between body mass and lateral abdominal muscle thickness assessed by ultrasound imaging. Therefore, it is reasonable to advise that the values of the allometric parameters for OE, OI, and TrA obtained in this study should be used in other studies performed on adolescents.

The importance of body mass normalisation for ultrasound measurement of the transversus abdominis muscle: The effect of age, gender and sport practice

BACKGROUND

Some studies have not considered body mass as a confounder in TrA analysis, which may have led to improper interpretation of results.

OBJECTIVES

To assess the differences in the effect of age, gender and physical activity between normalised for body mass and actual values of the TrA as well as to establish the effect of age, gender and physical activity on normalised for body mass TrA thickness in adolescents.

DESIGN

The study was a cross-sectional study conducted at selected primary and secondary schools, and colleges in the Silesian region of Poland.

METHOD

A real-time ultrasound was used to obtain images of the TrA muscle. Body mass normalisation for TrA thickness was performed with allometric scaling and the following equation: Allometric-scaled TrA = TrA thickness/body mass^0.61.

RESULTS

Analysis has shown that boys have significantly thicker muscle by 0.27 mm (95% CI 0.04-0.50) than girls, and those who practise sports have thicker muscle by 0.30 mm (95% CI 0.06-0.52) than non-active individuals. For allometric-scaled TrA, there were no significant effects (p > 0.50). There was a significant correlation between participants age and the actual value of the TrA (r = 0.42, p < 0.05). The correlation between age and allometric-scaled TrA was insignificant and close to zero (r = -0.006, p = 0.93).

CONCLUSIONS

An analysis of TrA thickness without body mass normalisation can deliver improper interpretation of study results. Thus, it is recommended in future researches to analyse TrA thickness measurement after normalisation rather than actual values. In the adolescent population, there is no effect of gender, age and physical activity on allometric-scaled TrA thickness.

Assessment of the abdominal muscles at rest and during abdominal drawing-in manoeuvre in adolescent physically active girls: A case-control study

BACKGROUND

An impact of regular physical activity (RPA) on the abdominal muscles may be significant when comparing various symptomatic groups. However, there is lack comprehensive information in this field. The objective of this study was to assess the lateral abdominal wall at rest and during abdominal drawing-in manoeuvre in adolescent physically active girls in different body positions.

METHODS

One hundred and forty-four female students, 13-17 years of age, participated in the study. Participants were divided into 2 groups based on a physical activity (PA) statement. Measurements of the thickness of the abdominal muscles at rest and during abdominal drawing-in manoeuvre were made in the supine and standing positions by ultrasound imaging.

RESULTS

Compared to the control group, activities of the obliquus internus and transversus abdominis muscles were higher in the regular PA group by 8.9% (95%CI: 3.1-14.7) and 36% (95%CI: 19.1-47.5), respectively. In the RPA group, the transversus abdominis preferential activation ratio was greater by 0.03 (95%CI: 0.01-0.04), and the contraction ratio was greater by a mean value of 0.35 (95%CI: 0.18-0.46).

CONCLUSION

RPA does not have any effect on the resting thickness of the abdominal muscles in the supine and standing positions. Girls performing RPA have a greater ability to perform an independent activation and greater contractions of the transversus abdominis.

Overall health status in patients with mild to moderate carpal tunnel syndrome: A case-control study

STUDY DESIGN

A case-control study.

INTRODUCTION

There are no reports in the literature that evaluate the overall health status (OHS) of patients with mild to moderate forms of carpal tunnel syndrome (CTS) using 36-Item Short Form Health Survey (SF-36).

PURPOSE OF THE STUDY

To assess OHS in patients with mild to moderate CTS, in comparison with healthy subjects.

METHODS

The study involved 273 healthy people and 140 people diagnosed with CTS. The CTS diagnosis was made on the basis of clinical examinations and nerve conduction studies. OHS was assessed using the SF-36.

RESULTS

In the assessment of physical components of OHS, in the CTS group (compared with healthy subjects), the results show significantly lower values in physical functioning, role limitations because of physical health problems, bodily pain, and general health perceptions by 7.44, 23.2, 18.9, and 4.1, respectively. Mental components were lower (in CTS group) only in relation to vitality and social functioning by 4.1 and 5.5, respectively. In the assessment of physical component summary (PCS) and mental component summary (MCS), the results show significantly lower values of PCS (by 13 in CTS group) and no significant differences in the assessment of MCS between patients with CTS and healthy subjects.

DISCUSSION

The perception of the OHS in CTS patients is diminished. Hence, when evaluating the effects of the therapy, not only disease-specific scales should be used, but also the OHS. This will allow an assessment of the impact of CTS on OHS and the impact of applied therapy, not only in terms of a reduction in the main symptoms of the condition.

CONCLUSIONS

Mild and moderate forms of CTS significantly affected the PCS of the OHS and all its subcomponents (physical functioning, role limitations because of physical health problems, bodily pain, and general health perceptions) but did not affect the MCS of OHS evaluated as a whole. There were significant differences in the mental component in the evaluation of vitality and social functioning.

LEVEL OF EVIDENCE

3.

Back and neck pain among school teachers in Poland and its correlations with physical activity

BACKGROUND

Back pain represents one of the most common diseases across various populations of workers worldwide. This study analyzes the prevalence and severity of back pain, based on selected demographic variables, and the relationship with physical activity among school teachers.

MATERIAL AND METHODS

The study included 998 professionally active teachers (840 females and 158 males) from the southern part of Poland. Validated psychometric tools, namely: 1) for evaluation of disability due to back pain - a Polish version of the Oswestry Disability Index (ODI) and Neck Disability Index (NDI), 2) for physical activity assessment - the Subjective Experience of Work Load (SEWL) as well as the authors' supplementary questionnaire, addressing demographic and anthropometric variables were used.

RESULTS

There was no correlation between age and the NDI scores in females (r = 0.027), in contrast to males (r = 0.202; p ≤ 0.05). Statistically significant correlations (p ≤ 0.05) were reported between: age and the ODI, in both females (r = 0.219) and males (r = 0.180). No associations between the body mass index (BMI)-ODI, and BMI-NDI were found. In the case of women, disability related to low back pain (LBP) had a negative impact on the indicators of their activity during work, sports, and leisure time. In the case of men, the NDI and ODI scores did not differ, based on activity indicators.

CONCLUSIONS

Our findings confirm that back pain represents a serious concern among teachers. Age appears to be a prognostic factor, while no association between the BMI and LBP has been revealed. The limitation of physical activity leads to more frequent back pain.

Intra-rater reliability of B-mode ultrasound imaging of the abdominal muscles in healthy adolescents during the active straight leg raise test

BACKGROUND

To date, the reliability of ultrasound imaging (USI) measures of the abdominal muscles in children and adolescents during the active straight leg raise (ASLR) test has not been confirmed.

OBJECTIVE

To assess the intra-rater reliability of USI measures of the thickness and percentage thickness change of the external oblique (EO), internal oblique (IO), and transversus abdominis (TrA) on both sides of the body during the ASLR test in healthy adolescents.

DESIGN

Single-group repeated-measures intra-rater reliability study.

SETTING

School.

PARTICIPANTS

Thirty-nine adolescents between the ages of 13 and 16 years.

METHODS

Three repeated USI measurements were recorded in the supine resting position and during the ASLR test at 2 sessions, 6 to 8 days apart. In the supine position, measurements were collected at the end of normal expiration. In the case of ASLR, measurements were collected when the person undergoing examination touched the transverse delimiter with the distal part of their lower leg, that is, to a 30° flexion of the hip.

MAIN OUTCOME MEASUREMENTS

USI of abdominal muscle thickness.

RESULTS

By using the mean of 3 measures in the supine, resting position, intra-examiner reliability point estimates (intraclass correlation coefficient [ICC]3.3) ranged from 0.95 to 0.97 for EO, IO, and TrA. During the ASLR test, the ICC result of thickness measurements of all muscles was also above 0.90. In terms of percentage change of muscle thickness, the highest ICC3.3 result obtained for the TrA was 0.81-0.85; for EO the result ranged from 0.72-0.89, and the result for the IO was between 0.65 and 0.79.

CONCLUSION

USI measurements of the thickness of the EO, IO, and TrA muscles at rest and during the ASLR test in healthy adolescents between 13 and 16 years of age are reliable. Because of an increase in the precision of measurements, we recommend using the mean of 3 consecutive measurements of the EO, IO, and TrA muscles in adolescents to ensure a good reliability level. Based on 3 consecutive measurements, good reliability for the percentage change in the TrA thickness was achieved.

Lateral abdominal muscle size at rest and during abdominal drawing-in manoeuvre in healthy adolescents

Lateral abdominal wall muscles in children and adolescents have not been characterised to date. In the present report, we examined the reliability of the ultrasound measurement and thickness of the oblique external muscle (OE), oblique internal muscle (OI) and transverse abdominal muscle (TrA) at rest and during abdominal drawing-in manoeuvre (ADIM) on both sides of the body in healthy adolescents. We also determined possible differences between boys and girls and defined any factors-such as body mass, height and BMI-that may affect the thickness of the abdominal muscles. B-mode ultrasound was used to assess OE, OI and TrA on both sides of the body in the supine position. Ultrasound measurements at rest and during ADIM were reliable in this age group (ICC3,3 > 0.92). OI was always the thickest and TrA the thinnest muscle on both sides of the body. In this group, an identical pattern of the contribution of the individual muscles to the structure of the lateral abdominal wall (OI > OE > TrA) was observed. At rest and during ADIM, no statistically significant side-to-side differences were demonstrated in either gender. The body mass constitutes between 30% and <50% of the thickness differences in all muscles under examination at rest and during ADIM. The structure of lateral abdominal wall in adolescents is similar to that of adults. During ADIM, the abdominal muscles in adolescents react similarly to those in adults. This study provided extensive information regarding the structure of the lateral abdominal wall in healthy adolescents.