Isometric Trunk Muscle Strength Research Articles

Hamstring and knee injuries are associated with isometric hip and trunk muscle strength in elite Australian Rules and Rugby League players

ObjectivesThis study investigated relationships between isometric trunk and hip extensor strength, lumbar muscle morphology, and the risk of hamstring and knee ligament injuries in Australian Football League and National Rugby League players. DesignProspective cohort study. MethodsTrunk and hip extensor strength, multifidus and quadratus lumborum cross-sectional area were measured during the 2020 pre-season. Logistic regressions and decision trees were employed to explore associations between maximum strength, strength endurance, multifidus and quadratus lumborum cross-sectional area, age, previous injuries, and hamstring and knee ligament injury risk. ResultsGreater strength endurance [odds ratio = 0.42 (0.23–0.74), p = 0.004] and maximum strength [odds ratio = 0.55 (0.31–0.94), p = 0.039] reduced hamstring injury risk. Increased risk of knee ligament injuries was associated with larger multifidus [odds ratio = 1.66 (1.14–2.45), p = 0.008] and higher multifidus to quadratus lumborum ratio (odds ratio = 1.57 (1.13–2.23), p = 0.008]. Decision tree models indicated that low strength endurance (< 99 Nm) characterised hamstring strains, while high (≥ 1.33) multifidus to quadratus lumborum ratio mitigated risk. Knee ligament injuries were associated with larger (≥ 8.49 cm2) multifidus, greater (≥ 1.25) multifidus to quadratus lumborum ratio, and lower maximum strength (< 9.24 N/kg). ConclusionsPlayers with lower trunk and hip extensor maximum strength and strength endurance had increased risk of hamstring injuries, while knee ligament injury risk was elevated with larger multifidus cross-sectional area, higher multifidus to quadratus lumborum ratio, and lower maximum trunk and hip extensor strength.

Correlation between upper limb function and clinical measures of shoulder and trunk mobility and strength in overhead athletes with shoulder pain

ObjectiveTo investigate the correlation between functional performance and self-reported upper limb function and between these two functional measures and clinical measures of shoulder and trunk in overhead athletes with shoulder pain. DesignCross-sectional study. SettingsLaboratory. ParticipantsTwenty-one volleyball and handball athletes (23.6 ± 3.7 years) with shoulder pain in the dominant limb. Main outcome measuresSelf-reported dominant upper limb function using Penn Shoulder Score and Disabilities of the Arm, Shoulder, and Hand; shoulder and trunk range of motion; isometric strength of shoulder, periscapular, and trunk muscles; endurance time of trunk muscles; and functional upper limb performance using the Upper Quarter Y-Balance Test (UQYBT). ResultsA moderate correlation was observed (r = 0.45–0.58; p < 0.05) between UQYBT performance and strength of serratus anterior, lower trapezius, trunk rotators, and trunk flexors. No significant correlation was observed between UQYBT performance and the other clinical measures of shoulder and trunk (r = 0.01–0.39, p > 0.05). Self-reported upper limb function was neither significantly correlated with clinical measures (r = 0.01–0.40, p > 0.05) nor with UQYBT performance (r = 0.02–0.19, p > 0.05). ConclusionWe observed a correlation between UQYBT performance and strength of periscapular and trunk muscles.

The effect of gender, age and sports specialisation on isometric trunk strength in Greek high level young athletes

ABSTRACT Aim of the study was to compare the isometric strength of flexors and extensors trunk muscles between male and female elite adolescent athletes of different age and training experience. Absolute and relative trunk muscle isometric peak extension (PTE) and flexion (PTF) torque, as well as flexion/extension (F/E) ratio were evaluated in 388 elite adolescent athletes 188 males (Age: 15.4±1.8 years, Body height: 175.5±11.2 cm, Body mass: 68.8±14.5 kg, BMI: 22.1±0.3 kg/m2) and 207 females (Age: 15.1±1.6 years, Body height: 166.8±7.8 cm, Body mass: 60.8±8.4 kg and BMI: 21.8±0.4 kg/m2). Participants were assigned into seven different groups according to their sport specialisation (oars-paddle, swimming, contact–combat, team, racket, winter and mixed other sports). Significant effect of age (η2: 0.077–0.112, p < 0.05), gender (η2: 0.020–0.077; p < 0.05) and sport category factors (η2: 0.057–0.154. p < 0.005) for absolute/relative PTE, PTF and F/E ratio was found. The highest values were observed in contact–combat and the lowest in mixed other sports groups. F/E ratio significantly differs between the age groups, especially in female athletes. The present data suggest that TMSs and F/E ratio are highly affected by age, gender and sports specialisation in high level trained adolescents.

Disability, kinesiophobia, perceived stress, and pain are not associated with trunk muscle strength or aerobic capacity in chronic nonspecific low back pain

ObjectivesTo investigate to which extent disability, psychological and pain-related factors are associated with the outcomes of an isometric trunk muscle strength test and a cardiopulmonary exercise test in persons with chronic nonspecific low back pain (CNSLBP). DesignCross-sectional study. SettingREVAL Rehabilitation Research Center (Hasselt, Belgium). ParticipantsPersons with CNSLBP. Main outcome measuresQuestionnaires concerning disability, patient specific functioning, kinesiophobia, perceived stress, pain intensity, and central sensitization were recorded. Outcomes of an isometric trunk strength test (maximum back and abdominal torque) and cardiopulmonary exercise test (VO2max) were assessed. Multivariate linear regression models determined factors explaining outcome variance. ResultsData of 101 persons (39 males, mean age: 44.2y (SD = 9.6)) was assessed. Neither disability, nor psychological, nor pain-related factors were associated with the assessments. Variance in back muscle strength (R2 = 0.44, F = p < 0.01), abdominal muscle strength (R2 = 0.68, F = p < 0.01), and aerobic capacity (R2 = 0.76, F = p < 0.01) could only be explained through the included demographics covariates (age, gender, weight). ConclusionThis study highlighted the lack of biopsychosocial factors in explaining variance in outcomes of abdominal and back strength, and aerobic capacity in persons with CNSLBP with characteristics as depicted in the current sample. This information supports the valid interpretation of the outcomes of these assessments.

Association between trunk muscle strength and static balance in older women

ABSTRACT The aim of this study was to determine the relationship between trunk muscle strength and balance ability in both simple and dual-task conditions in older women. Sixty-seven older women (age: 67.2 ± 1.1 years) volunteered in this study. Each participant performed isometric trunk muscle strength testing in standing position (extension, flexion, and lateral flexion) and balance testing in semitandem stance for 30 seconds in two conditions: with and without an additional cognitive task (counting down by 3 from 300). Balance was quantified via force plate as a mean velocity of center of pressure (CoP) displacement over 30 seconds. We found a statistically significant correlation between the trunk extensor strength and mean velocity of CoP displacement, both without (r = 0.5, p < .05) and with an additional cognitive task (r = 0.4, p < .05). There were no statistically significant correlations between trunk flexor and lateral flexors strength and balance measures (r < 0.2; p > .05). These results indicate that trunk extensor muscle strength is related to balance ability of healthy older women. Although additional studies are needed, our findings suggest that trunk strength training could be of importance in prevention of falls and fall-related injuries in seniors.

Musculoskeletal Condition and Adaptation as the Predictors of Low Back Pain in Sports Games

Objective. The objective of this systematic review of literature was to identify if the musculoskeletal condition and disorders caused by adaptation on specific movement patterns in sports games is as risk factors of low back pain (LBP). Data sources. A comprehensive search of articles published in the last 20 years was conducted in four databases (PubMed®, Google Scholar, Web of Science). Different combinations of keywords such as LBP, muscle imbalance, muscle strength, muscle endurance, musculoskeletal system and sport game were used, applying the Boolean operators. After establishing the criteria of selection, 9 studies of 52 initially identified were analyzed. Results. From the viewpoint of musculoskeletal condition and its functional adaptation as the possible risk factors of LBP in the sports games it is suggested that the musculoskeletal system, its functional disorders, endurance and maximal strength of the trunk muscles are not risk factors of LBP in every aspect. The risk factors appear to be muscle imbalances combined with functional asymmetry of pelvic and its asymmetrical rotation as a result of unilateral overloading, as well as the low maximal lumbar[ flexion. Low level of endurance of trunk and core muscles cannot be uniquely identified as a risk factor of LBP. Similarly, the maximal isometric strength of trunk muscles do not act as a risk factor of LBP, either. Conclusion. A detailed comparison of data between the sports games, within game, sex or age was not possible. Further research is necessary. Nevertheless, based on the results of this review, it is obvious that in sports games LBP is a consequence of functional and structural changes of pelvic and related muscles. There is less evidence for endurance and maximal isometric strength of trunk muscles to be a risk factor of LBP.

Reliability of a Test for Assessment of Isometric Trunk Muscle Strength in Elderly Women

Objective The aim of this study was to analyze the reproducibility of a protocol using the maximal isometric strength test of the trunk in elderly women aged above 60 years, without low back pain. Methods Twenty-one physically inactive elderly women, who had not engaged in any activity or exercise program in the past three months, participated in the cross-sectional study that consisted of two days of evaluations for the maximal isometric strength of the extensor and flexor muscles of the trunk, with a 48 h interval between the sessions. A platform with fixed seating was used, which allowed the fixation of the hip and lower limbs, with a load cell connected to a linear encoder. To verify the reliability of the test, the interclass correlation coefficient, variation coefficient, minimum detectable difference (MDD), standard error of measurement, and Bland–Altman graphs were calculated. Results No statistical difference was observed between the first and second evaluation, which indicates that there was no learning effect. Interclass correlation coefficient values were classified as very high and high for extensor (0.98) and flexor (0.86) muscles, respectively, besides low variation (9% for both muscle groups) and acceptable values for minimum detectable difference (extensors = 51.1 N, flexors = 48.9 N). In addition, the Bland–Altman analysis revealed low bias and values within the limits of agreement. Conclusion It is concluded that the test of maximum isometric strength of the trunk in healthy and trained elderly people presents high reliability. These values proved to be reliable if performed in at least two evaluation sessions, which confirms the hypothesis of the authors by the consistency of the measurement test.

Reliability and agreement of isometric functional trunk and isolated lumbar strength assessment in healthy persons and persons with chronic nonspecific low back pain

Objectivesto assess intra/inter-operator reliability and agreement of maximum isometric abdominal and back muscle strength in a functional trunk and isolated lumbar protocol, using an isokinetic dynamometer, in healthy persons and persons with chronic nonspecific low back pain (CNSLBP). DesignTest-retest. SettingParticipants performed two assessments consisting of two protocols on the Biodex 3 system, evaluating maximum isometric back and abdominal strength in a functional trunk and isolated lumbar position. During the first assessment, each protocol was executed twice, supported by different operators. ParticipantsHealthy persons (n = 20) and persons with CNSLBP (n = 20). Main outcome measuresIntraclass Correlation (ICC), Standard Error of Measurement (SEM and %SEM), and Minimal Detectable Change (MDC) of muscle strength outcomes and seat positioning characteristics were calculated. ResultsIntra/inter reliability of muscle strength outcomes was excellent (ICC: 0.94–0.98), while seat positioning characteristics varied from low to high (ICC: 0–0.94). For muscle strength outcomes, %SEM ranged from 4.7 to 9.2% and MDC ranged from 14.3 to 29.8 Nm in trunk flexion and 39.1–68.5 Nm in trunk extension. ConclusionsThe Biodex 3 system can be used reliably to assess maximum isometric trunk muscle strength with the aforementioned protocols in healthy persons and persons with CNSLBP. All muscle strength outcomes showed comparable agreement (%SEM < 10%).

Features of trunk muscle weakness in patients with ankylosing spondylitis: A cross-sectional study

BackgroundAnkylosing spondylitis (AS) is an inflammatory autoimmune disorder that manifested with sacroiliitis at its early stage and developed extensive inflammation with syndesmophytes of the lumbar, thoracic and cervical spines at its later stage. In the present study, we characterized the trunk isometric strength in patients with AS with different disease severity, defined by the radiological images. MethodsIn a cross-sectional study conducted in a university-affiliated hospital, thirty-eight male AS patients (23 in the early AS group whose radiological findings showed no syndesmophyte, Modified Stoke Ankylosing Spinal Score (m-SASSS <3); and 15 in the syndesmophyte group, m-SASSS ≥24), and 22 healthy controls were recruited. All subjects received assessments of maximum isometric strength of trunk flexor and extensor muscles at a variety of trunk postures measured by an isokinetic device. ResultsUnder all examined trunk postures, the syndesmophyte AS patient group had the lowest isometric trunk muscle strength among the three groups. The flexion/extension ratio, defined by the ratio between isometric trunk flexor and extensor strengths, was highest among the three groups. ConclusionsTrunk muscle strength significantly decreases in patients with syndesmophyte AS. The decrease of trunk muscle is inhomogeneous, which is more profound in extensor than in flexor muscles.

Pain and functional outcomes after outpatient physiotherapy in patients with low back pain.

Physiotherapy treatment programs are recommended in the rehabilitation of low back pain (LBP). Rehabilitation institutions are increasingly asked to demonstrate the outcomes of their intensive physiotherapy services. To describe pain and functional outcome measures following a6-month outpatient physiotherapy treatment program in patients with LBP. A total of 85patients were analysed after being treated with acombination of physiotherapeutic treatment modalities 2-3days weekly. Pain and disability were measured before, 3 and 6months after the onset of treatment. Isometric trunk muscle strength for flexion and extension and flexibility of dorsal trunk and thigh structures were measured before and 6months after treatment. After 6months, pain at rest decreased from amedian of 4.0 to 0.0 (p< 0.01) and pain during activity from amedian of 5.5 to 2.0 on the numeric rating scale (p< 0.001). The Roland-Morris Disability (RMDQ) score decreased from amedian of 7.0 to 3.0 (p< 0.001). Mean trunk muscle flexion strength increased from 133.7 to 156.0 Nm and for extension from 235.5 to 278.3 Nm (p< 0.001). Flexibility was improved from amean of -5.9 to -1.4 cm (p< 0.001). Amoderate correlation between pain at rest and RMDQ score was found after 3 (r= 0.532, p< 0.01) and 6months (r= 0.508, p< 0.01). Patients with LBP who were treated with the physiotherapeutic treatment program showed aclinically relevant reduction of pain and disability with improved trunk muscle strength and flexibility. Reductions in pain and disability do not seem to correlate with increased trunk muscle strength and flexibility. No conclusions can be declared about long-term changes after the intervention.

Clinical, physical, and radiographic analyses of lumbar degenerative kyphosis and spondylolisthesis among community-based cohort.

To investigate longitudinal radiographic changes, and physical characteristics of lumbar degenerative kyphosis (LDK) and spondylolisthesis (DS). Two-hundred eighty nine community-based female subjects were recruited from population register and studied longitudinally for a mean 12.3years. Upright entire spine radiographs were used to evaluate spinopelvic parameters, including lumbar lordosis (LL), pelvic incidence (PI), and vertebral slip (% slip). Physical measurements included lumbar range of motion (ROM), isometric trunk muscle strength, and photometric gait posture using change in trunk inclination angle (dTIA). Subjects' mean age (standard deviation: SD) was 56.9 (10.0) years at baseline and 68.5 (9.2) years at the final follow-up. Among 202 subjects who could perform instructed physical measurements, DS, defined as more than 5% slip, was found in 50 subjects (24.8%), and LDK, defined as LL of less than 1SD of mean value (<24.4°), was found in 24 subjects (11.9%). DS subjects showed a significant weakness in trunk flexor strength (normal 282.5±73.0N vs. DS 245.5±75.5N, p=0.0219), and LDK subjects showed significant differences in: trunk extensor strength (normal 493.4±172.8N vs. LDK 386.3±167.6N, p=0.0066), ROM, and dTIA (normal 3.5°±2.7° vs. LDK 7.6°±4.8°, p<0.0001). PI was significantly larger in DS and smaller in LDK than normal subjects (normal 53.8°±9.9° vs. DS 58.2°±10.6°, p=0.0111; normal vs. LDK 48.4°±9.2°, p=0.0191). Current study showed that DS was associated with reduced trunk flexor strength, which might increase pelvic anteversion, and LDK was associated with reduced extensor strength, ROM, and ambulatory kyphosis. Physical characteristics should be evaluated for the successful management of adult spinal deformity.

Reliability and validity of a custom-made instrument including a hand-held dynamometer for measuring trunk muscle strength.

Measuring isometric strength is necessary in many areas of health and sport. However, trunk muscles have some particular characteristics that make them difficult to evaluate with simple, inexpensive instruments. To evaluate the reliability and validity of an instrument constructed with a hand-held dynamometer and a metallic structure (HHD+S) for measuring maximum isometric voluntary trunk muscle strength. Maximum isometric voluntary trunk muscle strength (extension, flexion and lateral flexion) was measured in 20 healthy individuals using the custom-made instrument (HHD+S) and the gold standard Back-Check (BC). The results showed that the two instruments had high and similar intra-subject reliability. The validity of the HHD+S was demonstrated by the high Pearson coefficient correlation between the two instruments (r ⩾ 0.78). Given the good trial reliability and the close correlation between the two instruments, we believe that the use of a hand-held dynamometer together with the custom-made metallic structure (HHD+S) allows an evaluation of the maximum isometric voluntary trunk muscle strength to be made, that is very similar in quality, accuracy and reliability to the BC.

Prospective study of spinal orthoses in women.

There are not many clinical trials investigating the efficiency and compliance of using spinal orthoses in the management of osteoporosis. The purpose of this study was to investigate the effect of long-term use and the compliance of spinal orthoses in postmenopausal women with vertebral fractures. Clinical trial of spinal orthoses in postmenopausal women. Women were separated into groups wearing different types of orthoses (Spinomed, Osteomed, Spinomed active, and Spine-X). Isometric maximum strength of trunk muscles (F/Wabdominals-extensors) was calculated and back pain was assessed in all women. In addition, women completed a compliance questionnaire about the use of the orthoses. Spinomed decreased pain (p = 0.001) and increased trunk muscle strength (F/Wabdominals, p = 0.005 and F/Wextensors, p = 0.003, respectively). The compliance of wearing an orthosis for 6 months was 66%. The results suggest that orthoses could be an effective intervention for back pain and muscle strengthening in osteoporotic women. In women with established osteoporosis, wearing Spinomed orthosis for at least 2 h/day for 6 months decreased back pain significantly and increased personal isometric trunk muscle strength. All spinal orthoses could be valuable instruments to help all requested rehabilitation programs like spine muscles' strengthening and postural correct behavior, but only when used properly.

Screen time viewing behaviors and isometric trunk muscle strength in youth.

The objective of this study was to examine the association of screen time viewing behavior with isometric trunk muscle strength in youth. A cross-sectional study was carried out including 606 adolescents (14-16 yr old) participating in the Danish European Youth Heart Study, a population-based study with assessments conducted in either 1997/1998 or 2003/2004. Maximal voluntary contractions during isometric back extension and abdominal flexion were determined using a strain gauge dynamometer, and cardiorespiratory fitness (CRF) was obtained using a maximal cycle ergometer test. TV viewing time, computer use, and other lifestyle behaviors were obtained by self-report. Analyses of association of screen use behaviors with isometric trunk muscle strength were carried out using multivariable adjusted linear regression. The mean (SD) isometric strength was 0.87 (0.16) N·kg-1. TV viewing, computer use, and total screen time use were inversely associated with isometric trunk muscle strength in analyses adjusted for lifestyle and sociodemographic factors. After further adjustment for CRF and waist circumference, associations remained significant for computer use and total screen time, but TV viewing was only marginally associated with muscle strength after these additional adjustments (-0.05 SD (95% confidence interval, -0.11 to 0.005) difference in strength per 1 h·d-1 difference in TV viewing time, P = 0.08). Each 1 h·d-1 difference in total screen time use was associated with -0.09 SD (95% confidence interval, -0.14 to -0.04) lower isometric trunk muscle strength in the fully adjusted model (P = 0.001). There were no indications that the association of screen time use with isometric trunk muscle strength was attenuated among highly fit individuals (P = 0.91 for CRF by screen time interaction). Screen time use was inversely associated with isometric trunk muscle strength independent of CRF and other confounding factors.

Reproducibility and Reference Values of Inclinometric Balance and Isometric Trunk Muscle Strength Measurements in Finnish Young Adults

The objectives of the study were to evaluate the reproducibility of the maximal isometric trunk muscle strength testing and inclinometric method to measure body sway and to establish reference values for these measurements in young Finnish adults. Reproducibility was assessed with 2 repeated measurements. Reference values are based on the cross-sectional cohort data. Maximal isometric trunk extension, flexion, and rotations were measured in standing posture. Body sway was measured with inclinometric method. The subjects (N = 874) belonged to a subcohort of the Northern Finland Birth Cohort 1986. Intrarater reliability was assessed with 19 volunteers from the birth cohort, and interrater reliability was assessed with 15 young healthy adults. Intrarater reliability intraclass correlation coefficients (ICCs) for body sway measurements ranged from 0.39 to 0.74 and for trunk muscle strength measurements from 0.84 to 0.94. Interrater reliability ICC for body sway ranged from 0.61 to 0.85 and for trunk muscle strength from 0.84 to 0.88. Maximal muscle strength was better in men than in women, but extensor to flexor ratio was higher in women. Women had significantly better values in all body sway measurements than men. Our study showed a remarkable biological variation in isometric trunk muscle strength and inclinometric body sway. Although ICC analysis indicated good reliability, the Bland and Altman analysis revealed quite wide range of measurement error. However, reproducibility of isometric trunk muscle testing is comparable to other measurements of trunk muscle function in use. Reference values collected in our study offer valuable normative data for future studies and can be used as a tool when assessing physical capacity of healthy subjects or patients with different pathological conditions.

Design and evaluation of a novel triaxial isometric trunk muscle strength measurement system

Maximal strength measurements of the trunk have been used to evaluate the maximum functional capacity of muscles and the potential mechanical overload or overuse of the lumbar spine tissues in order to estimate the risk of developing musculoskeletal injuries. A new triaxial isometric trunk strength measurement system was designed and developed in the present study, and its reliability and performance was investigated. The system consisted of three main revolute joints, equipped with torque sensors, which intersect at L5-S1 and adjustment facilities to fit the body anthropometry and to accommodate both symmetric and asymmetric postures in both seated and standing positions. The dynamics of the system was formulated to resolve validly the moment generated by trunk muscles in the three anatomic planes. The optimal gain and offset of the system were obtained using deadweights based on the least-squares linear regression analysis. The R2 results of calibration for all loading courses of all joints were higher than 0.99, which indicated an excellent linear correlation. The results of the validation analysis of the regression model suggested that the mean absolute error and the r.m.s. error were less than 2 per cent of the applied load. The maximum value of the minimum detectable change was found to be 1.63 Nm for the sagittal plane torque measurement, 0.8 per cent of the full-scale load. The trial-to-trial variability analysis of the device using deadweights provided intra-class correlation coefficients of higher than 0.99, suggesting excellent reliability. The cross-talk analysis of the device indicated maximum cross-talks of 1.7 per cent and 3.4 per cent when the system was subjected to flexion-extension and lateral bending torques respectively. The trial-to-trial variability of the system during in-vivo strength measurement tests resulted in good to excellent reliability, with intra-class correlation coefficients ranging from 0.69 to 0.91. The results of the maximum voluntary isometric torques exertion measurements for 30 subjects indicated good agreement with the previously published data in the literature. The extensive capabilities and high reliability of the system are promising for more comprehensive investigations on the trunk biomechanics in future, e.g. isometric strength measurement at symmetric and asymmetric postures, muscle endurance, and recruitment pattern analysis.

Isometric Trunk Muscle Strength and Body Sway in Relation to Low Back Pain in Young Adults

A cross-sectional study on young adults. To evaluate the relationships between low back pain (LBP), maximal isometric trunk muscle strength, and body sway among young adults. The results of previous studies evaluating the association between trunk muscle strength and LBP are conflicting and heterogeneous. Furthermore, there are only few studies on the association between body sway and LBP. The subjects (n = 874) belonged to a subcohort of the Northern Finland Birth Cohort 1986 (mean age 19 years). Trunk muscle strength and body sway were measured from all subjects. LBP symptoms were inquired with a questionnaire, which was completed concurrently with the examinations. Latent Class Analysis (LCA) was used to cluster the subjects according to their LBP symptoms. LCA analysis produced 6 clusters differing with respect to LBP symptoms. There were no statistically significant differences between the clusters in trunk muscle strength or body sway. LBP does not seem to be associated with maximal isometric trunk muscle strength or body sway in young adults.

Physical Characteristics of Women With Severe Pelvic Girdle Pain After Pregnancy

Descriptive cohort study. This study aims to further elucidate the differences in physical characteristics of women with severe pregnancy-related pelvic girdle pain (PGP). There is increasing interest in pelvic girdle pain (PGP). To our knowledge, this is the first study on a large population of patients with severe PGP, after pregnancy, based on high cutoff scores on diagnostic PGP tests. Two hundred five patients were selected from the outpatient clinic of a rehabilitation center. Patients were divided in 3 inclusion groups based on the total number of positive scores on 5 diagnostic tests; i.e., active straight leg raise test, posterior pelvic pain provocation test, long dorsal sacroiliac ligament test, and hip abduction and adduction strength tests. These inclusion groups were related to the data on trunk strength test, general provocation tests, Quebec Back Pain Disability Scale (QBPDS) and activities of daily living. A typical pattern of PGP emerges from this study. The mean group score on the active straight leg raise, posterior pelvic pain provocation, and long dorsal sacroiliac ligament tests became higher when more than 3 inclusion tests were positive. Hip abduction and adduction strength became lower with more positive tests. The QBPDS score was overall high and significantly higher for 5 positive tests compared with 3 and 4 positive tests. This shows that the number of positive tests, the individual score on the diagnostic tests, and the QBPDS could all be an indicator for severity of PGP. Among the general pain provocation tests, both the passive hip flexion test and the upper and middle sacral thrust test scored high. The maximal isometric strength of trunk muscles was below the 10th percentile compared with women without complaints and was even less for 5 positive inclusion tests. It is confirmed that there is a typical order for difficulties with daily activities for PGP patients as follows (most difficult first): standing still, cycling, walking, sitting, and lying. The study shows that the level of severity in PGP can be adequately assessed by a combination of specific tests.

Inter-session, inter-tester and inter-site reproducibility of isometric trunk muscle strength measurements

The purpose of this study was to investigate the inter-session, inter-tester and inter-site reproducibility of trunk muscle strength scores in flexion, extension, lateral flexion and rotation. Ten healthy students were tested on four apparatus with a 7-10 day break between sessions. The first two sessions were identical while the other two differed either by the tester or by the site. Furthermore, 10 patients with chronic low back dysfunction (CLBD) were assessed with the four apparatus, once only. For all tests, CV ranged from 3.4% to 7.6% and from 3.9% to 8.1% in the inter-session and inter-tester studies, respectively ( p> 0.05 except for inter-session reproducibility of trunk flexor strength). Peak torque (PT) was more variable from site to site with a CV ranging from 4.2% to 12.7%, particularly in extension and left lateral flexion ( p< 0.05). No statistically significant difference in the strength ratios (flexion/extension, right/left lateral-flexion and right/left rotation) were found between sessions or testers (4.9% < CV < 9.7%). The inter-site reproducibility of ratios was lower. Comparison between the CLBD patients and the healthy subjects with regard to PT normalized to body weight indicated significantly decreased performance for the former except for flexion and rotation scores in males. We conclude that in the case of healthy subjects, inter-session and inter-tester trunk strength measurements derived from these devices are reproducible. The low inter-site reproducibility suggests that caution should be exercised when interpreting findings originating from different sites. The lower extension strength scores in CLBD patients test lends some validity to the system. However, further studies focusing on reproducibility and validity of this system in CLBD patients are critical before any conclusion regarding their clinical viability may be drawn.

Part 1: Abstracts of presentations

To investigate the correlation between functional performance and self-reported upper limb function and between these two functional measures and clinical measures of shoulder and trunk in overhead athletes with shoulder pain.Cross-sectional study.Laboratory.Twenty-one volleyball and handball athletes (23.6 ± 3.7 years) with shoulder pain in the dominant limb.Self-reported dominant upper limb function using Penn Shoulder Score and Disabilities of the Arm, Shoulder, and Hand; shoulder and trunk range of motion; isometric strength of shoulder, periscapular, and trunk muscles; endurance time of trunk muscles; and functional upper limb performance using the Upper Quarter Y-Balance Test (UQYBT).A moderate correlation was observed (r = 0.45–0.58; p < 0.05) between UQYBT performance and strength of serratus anterior, lower trapezius, trunk rotators, and trunk flexors. No significant correlation was observed between UQYBT performance and the other clinical measures of shoulder and trunk (r = 0.01–0.39, p > 0.05). Self-reported upper limb function was neither significantly correlated with clinical measures (r = 0.01–0.40, p > 0.05) nor with UQYBT performance (r = 0.02–0.19, p > 0.05).We observed a correlation between UQYBT performance and strength of periscapular and trunk muscles.