G. Luder

Isometric rate of force development, maximum voluntary contraction, and balance in women with and without joint hypermobility.

OBJECTIVE To determine differences between hypermobile subjects and controls in terms of maximum strength, rate of force development, and balance. METHODS We recruited 13 subjects with hypermobility and 18 controls. Rate of force development and maximal voluntary contraction (MVC) during single leg knee extension of the right knee were measured isometrically for each subject. Balance was tested twice on a force plate with 15-second single-leg stands on the right leg. Rate of force development (N/second) and MVC (N) were extracted from the force-time curve as maximal rate of force development (= limit Deltaforce/Deltatime) and the absolute maximal value, respectively. RESULTS The hypermobile subjects showed a significantly higher value for rate of force development (15.2% higher; P = 0.038, P = 0.453, epsilon = 0.693) and rate of force development related to body weight (16.4% higher; P = 0.018, P = 0.601, epsilon = 0.834) than the controls. The groups did not differ significantly in MVC (P = 0.767, P = 0.136, epsilon = 0.065), and MVC related to body weight varied randomly between the groups (P = 0.921, P = 0.050, epsilon = 0.000). In balance testing, the mediolateral sway of the hypermobile subjects showed significantly higher values (11.6% higher; P = 0.034, P = 0.050, epsilon = 0.000) than that of controls, but there was no significant difference (4.9% difference; P = 0.953, P = 0.050, epsilon = 0.000) in anteroposterior sway between the 2 groups. CONCLUSION Hypermobile women without acute symptoms or limitations in activities of daily life have a higher rate of force development in the knee extensors and a higher mediolateral sway than controls with normal joint mobility.

Neuromechanical gait adaptations in women with joint hypermobility —An exploratory study

BACKGROUND Joint hypermobility is known to be associated with joint and muscle pain, joint instability and osteoarthritis. Previous work suggested that those individuals present an altered neuromuscular behavior during activities such as level walking. Therefore, the aim of this study was to explore the differences in ground reaction forces, temporal parameters and muscle activation patterns during gait between normomobile and hypermobile women, including symptomatic and asymptomatic hypermobile individuals. METHODS A total of 195 women were included in this cross-sectional study, including 67 normomobile (mean 24.8 [SD 5.4] years) and 128 hypermobile (mean 25.8 [SD 5.4] years), of which 56 were further classified as symptomatic and 47 as asymptomatic. The remaining 25 subjects could not be further classified. Ground reaction forces and muscle activation from six leg muscles were measured while the subjects walked at a self-selected speed on an instrumented walkway. Temporal parameters were derived from ground reaction forces and a foot accelerometer. The normomobile and hypermobile groups were compared using independent samples t-tests, whereas the normomobile, symptomatic and asymptomatic hypermobile groups were compared using one-way ANOVAs with Tukey post-hoc tests (significance level=0.05). FINDINGS Swing phase duration was higher among hypermobile (P=0.005) and symptomatic hypermobile (P=0.018) compared to normomobile women. The vastus medialis (P=0.049) and lateralis (P=0.030) and medial gastrocnemius (P=0.011) muscles showed higher mean activation levels during stance in the hypermobile compared to the normomobile group. INTERPRETATION Hypermobile women might alter their gait pattern in order to stabilize their knee joint.

Stair climbing – An insight and comparison between women with and without joint hypermobility: A descriptive study

Generalized joint hypermobility (GJH) is a frequent entity in rheumatology with higher prevalence among women. It is associated with chronic widespread pain, joint dislocations, arthralgia, fibromyalgia and early osteoarthritis. Stair climbing is an important functional task and can induce symptoms in hypermobile persons. The aim of this study was to compare ground reaction forces (GRF) and muscle activity during stair climbing in women with and without GJH. A cross-sectional study of 67 women with normal mobility and 128 hypermobile women was performed. The hypermobile women were further divided into 56 symptomatic and 47 asymptomatic. GRFs were measured by force plates embedded in a six step staircase, as well as surface electromyography (EMG) of six leg muscles. Parameters derived from GRF and EMG were compared between groups using t-test and ANOVA. For GRF no significant differences were found. EMG showed lower activity for the quadriceps during ascent and lower activity for hamstrings and quadriceps during descent in hypermobile women. For symptomatic hypermobile women these differences were even more accentuated. The differences in EMG may point towards an altered movement pattern during stair climbing, aimed at avoiding high muscle activation. However, differences were small, since stair climbing seems to be not demanding.

AB1100-HPR Effect of Resistance Training in Women with Joint Hypermobility – Preliminary Results of A Randomised Controlled Trial

Background Little is known about the clinical management of persons with generalized joint hypermobility (GJH). Affected persons are often restricted in performing sports or leisure activities, as well as during work, due to pain and disability (1). Adequate muscle strength for movement control might be an important issue to overcome these restrictions. Resistance training has the possibility to improve muscle strength (2), but so far no study investigated how resistance training influences strength and muscle size in women with GJH. Objectives To evaluate the effects of a 12-week resistance training program on muscle properties of women with GJH. Methods This pragmatic randomised controlled trial included 51 hypermobile women (mean age 26.5, sd 4.5 years) with a Beighton-score of six or more (3). 27 women performed for 12 weeks a guided resistance training twice weekly and 24 women did not exercise. Before and after the 12 weeks maximum isometric strength of knee extensors and flexors was measured, which was the primary outcome. Additionally muscle cross-sectional-area (mCSA) of the thigh was measured at 33% above the knee, using peripheral quantitative computer tomography (pQCT). Data were analysed on an intention-to-treat basis. Differences between groups were tested with independent t-test at a significance level of p=0.05. Results The groups were comparable at baseline. Change of maximum strength of knee extensors in the training group was 6.3 N (sd 57.7, CI -16.5 to 29) and in the control group 8.3 N (sd 42.1, CI -9.4 to 26.1), with no significant difference between groups. Similar results were seen for knee flexors: change in training group was 8.0 N (sd 59.8, CI -15.6 to 31.7) and in control group 16.1 N (sd 42.8, CI -2.0 to 34.2). Muscle CSA of the thigh in the training group showed a significant increase (194 mm2, CI 78 to 310 mm2), compared to the control group (46 mm2, CI -25 to 118 mm2; p=0.031). Muscle mass at the thigh significantly increased 19.1 mg (sd 27.3, CI 8.3 to 29.9) in the training group, compared to the control group with 4.3 mg (sd 14.4, CI -1.8 to 10.33) mean change. Muscle density, however, showed no change in both groups. Conclusions The 12-week resistance training did not change isometric knee muscle strength, but led to a significant increase of mCSA of the thigh in women with GJH. However, this difference was only 2.4% and thus may not be clinically significant. In strength testing possibly no change was seen because the dynamic training could not be transformed to the isometric test condition and the intensity of the training might not have been high enough. The detailed analysis of the training protocols will provide further details concerning this issue. However, the small increase in muscle area may indicate that strength training is a possible option for these hypermobile women. Further analysis of the additional measurements in this trial, may give more insight into changes in pain or disability. Further research should investigate if the muscle increase could be optimized by a more intense or better supervised training. References Simmonds & Keer, Manual Therapy. 2007:298–309 Roth et al. J Am Geriatr Soc. 2001:1428–1433. Remvig et al. The Journal of Rheumatology. 2007:798–803 Acknowledgement The study was approved by the Ethics Committee of Canton Bern (222/12). Disclosure of Interest None declared

Passive anterior tibial translation in women with and without joint hypermobility: an exploratory study.

Generalized joint hypermobility (GJH) is a frequent entity, which is still not fully understood. Symptoms associated with GJH are musculoskeletal disorders, decreased balance, impaired proprioception and chronic pain. The purpose of this study was to compare the passive anterior tibial translation (TT) in terms of distance and corresponding force between normomobile (NM) and hypermobile (HM) as well as between NM, symptomatic (HM‐s) and asymptomatic (HM‐as) hypermobile women.

THU0622-HPR Discriminating Conditional and Functional Factors for Women with and Without Hypermobility – an Observational Study

Background Generalized joint hypermobility (GJH) is often seen and widely underestimated regarding complexity of diagnosis and treatment. The prevalence of GJH was reported between 10% and 18%, with women more often affected (1). Diagnosis is mainly based on the Beighton score (BS), which is based on increased range of motion (ROM) in specific joints like knee, elbow and fingers (2). However, little is known about the importance of conditional factors like muscle strength or balance in persons with GJH, and their influence on pain and disability. Objectives Aim of this study was to find factors discriminating between hypermobile women with and without symptoms, and women with normal mobility. Methods A total of 195 women (mean age 25.5 years) were included in this cross-sectional study, whereby 67 were normomobile, 56 symptomatically hypermobile and 47 asymptomatically hypermobile. Hypermobile women had BS of 6 or higher and classification according to symptoms was based on self-reported pain during 6 months. Measurements comprised passive anterior translation of the tibia, passive ROM of the knees, BS, muscle strength, balance during single-leg standing, as well as muscle activity (MA) and ground reaction forces (GRF) during gait and stair climbing. The main parameters of every measurement were included in a principle component analysis (PCA) and all factors with eigenvalue>1 were extracted (3). Main components of these factors were derived from the variables to describe possible discriminating factors between groups. Results 17 principle components showed eigenvalue>1 and were included in further analysis. Together they accounted for 80% of variance between groups. The five most important factors (eigenvalue>3) accounted for 46% of variance. These factors were composed as follows: #1 (13.7% of variance) consisted of GRF parameters during gait and on stair, #2 (11.0%) was balance as well as quadriceps and hamstrings MA during gait and on stair, #3 (8.4%) included strength of knee extensors and balance, #4 (6.2%) was composed of MA of lower leg muscles on stair, strength of knee flexors, body weight and BMI and #5 (5.7%) was based on passive ROM of knee, BS and passive tibial translation. Conclusions PCA could not reduce the variables on few factors. Contrariwise, 17 factors remained and the five most important could explain less than 50% of the variance between groups. Furthermore, yet these five factors consisted of several variables derived from different measurements. In general MA was not very important and passive ROM occurred not before factor #5, as well as BS. The high number of extracted factors might be a sign of the complex nature of hypermobility. BS and passive ROM seemed not to be the primary factors to discriminate between women with hypermobility and with normal mobility. The measurements were probably not enough demanding for young women to clearly discriminate symptomatic hypermobile women from asymptomatic hypermobile women. References Simmonds & Keer, Manual Therapy. 2007:298-309. Remvig et al. The Journal of Rheumatology. 2007:798-803. Field: Discovering Statistics using SPSS, London, 2013. Acknowledgements The project was supported by the Swiss National Science Foundation (# 13DPD6 127285) and approved by the Ethics Committee of Canton Bern, Switzerland (Number 229/2008). Disclosure of Interest None declared

THU0623-HPR Joint Hypermobility – is There a Correlation Between Muscle Cross Sectional Area and Muscle Strength?

Background Generalized Joint Hypermobility (GJH) is often underestimated and little is known about clinical implications and optimal treatment. Hypermobile persons are often restricted in performing sports or leisure activities, as well as during work, due to pain and disability (1). Adequate muscle strength for movement control might be an important issue to overcome these restrictions. However, little is known about muscle properties of women with GJH. Although it is commonly recognized that strength and muscle cross-sectional area (CSA) are related, the exact relationship seems complex and remains unclear. Objectives The aim of the study was to analyze the correlation between muscle strength and muscle CSA in women with GJH. Methods This cross-sectional study included 52 hypermobile women (mean age 26.7±4.7 years, weight 62.4±10.8 kg, BMI 22.8±3.6 kg/m2) with a Beighton-score of six or more (2). Maximum isometric muscle strength for knee extensors and flexors was measured and calculated as maximal voluntary contraction (MVC) and rate of force development (RFD). Muscle CSA of thigh was measured at one third above knee using peripheral quantitative computer tomography (pQCT). Parameters were calculated as absolute values and related to body weight. Correlation coefficients according to Pearson (r) were calculated, as well as the coefficient of determination (r2) in percent. Significance level was set at p=0.05. Results For the absolute values significant correlations were found between MVC and muscle CSA with r=0.46 (r2=21%, p<0.001) for knee extensors and r=0.29 (r2=9%, p=0.035) for flexors. Values related to body weigh showed comparable correlations for MVC and additional significant correlation between RFD of knee extensors and CSA with r=0.31 (r2=9%, p=0.028). Regarding strength, the correlation between MVC and RFD for extensors was significant at a middle level (r=0.52, r2=27%, p<0.001), as well as for flexors (r=0.56, r2=32%, p<0.001). Between flexors and extensors correlations were middle, with r=0.69 (r2=48%, p<0.001) for MVC and r=0.51 (r2=26%, p<0.001) for RFD. Finally, body weight was correlated with muscle CSA (r=0.52, r2=27%, p<0.001), only weak with MVC of extensors (r=0.26, r2=7%, p=0.059), but not with RFD of extensors (r=0.009). Conclusions Maximum strength of knee extensors and flexors was correlated with muscle CSA of thigh, with values comparable to studies with healthy or exercising people (3). Correlations were highly significant, but on a low level with r2 from 9 to 21%. This indicates that muscle CSA is not solely responsible for the determination of adequate muscle strength. The fact that RFD of knee extensors was only correlated when related to body weight, may point to the importance of fibre type distribution and neuromuscular control (4). In contrast MVC is more dependent on muscle CSA. To conclude, muscle strength is a complex phenomenon, especially RFD and depends on various factors, not solely on muscle CSA. References Simmonds & Keer, Manual Therapy 2007:298-309. Remvig et al. The Journal of Rheumatology 2007:798-803. Remvig et al. The Journal of Rheumatology 2007:798-803. Jones et al. Sports Med 2008:987-994. Andersen & Aagard, Eur J Appl Physiol 2006:46-52. Acknowledgements The study was approved by the Ethics Committee of Canton Bern (222/12). Disclosure of Interest None declared

FRI0583-HPR Stair climbing - an insight and comparison between women with and without joint hypermobility

Background Joint hypermobility (JH) is a frequent and important entity in rheumatology, which has not received adequate attention and is still not fully understood. Perceived joint instability, a higher risk for joint distortions and chronic pain are the major problems in affected persons(1). Even fibromyalgia, chronic fatigue syndrome or early osteoarthritis were recently associated with JH(2). Stair climbing is an important functional task and can lead to pain or joint instability in JH. Especially in stair descent fast stabilization of the joints is important, while the maximal vertical force of about 1.5 times body weight is reached in 150 ms after foot contact in healthy(3). However, muscle activation and ground reaction force paaterns during stair climbing in persons with JH remain unknown. Objectives To explore whether differences exist in the muscle activation and ground reaction forces (GRF) between women with and without JH. Secondary aim was to detect differences between hypermobile women with and without symptoms. Methods 170 women participated in this cross-sectional study: 67 normomobile (24.8±5.4 years), 56 hypermobile with symptoms (25.3±5.4 y) and 47 hypermobile without symptoms (25.7±5.3 y). Groups were identified using the Beighton Score. Symptoms were recorded monthly for half a year and all women mentioning at one time-point pain or disability were classified as symptomatic. GRF were measured with two force plates embedded in a six step staircase. EMG of six leg muscles was measured with surface electrodes. For GRF first maximum peak was calculated and normalized to body weight. Timing of first peak and total contact time were evaluated(3). EMG was normalized to maximum voluntary contraction. The linear envelope (Lowpassfilter at 20 Hz) of six strides was averaged and peak activation was calculated, as well as the activation level at first force peak(4). Group comparisons were done by oneway ANOVA and post-hoc with Tukey-test, at a significance level p≤0.05. Results Groups did not differ in age, weight and height. For GRF parameters no significant difference was found between the groups. For stair ascent the EMG measurements showed significant lower activation levels for vastus medialis in both hypermobile groups and no difference in all other muscles. During descent only the semitendinosus muscle had significantly lower maximal activation in both hypermobile groups. Conclusions GRF revealed no differences between groups and in the EMG measurements only two muscles showed differences. This may indicate that the JH of these women did not affect their ability to negotiate stairs. Furthermore it made no difference whether the women had pain or disability in daily life. A possible explanation is that the women in this study had mild to moderate symptoms and not all of them reported their problems in the lower extremity joints. Finally stair climbing might have not been challenging enough for these rather young persons to show possible differences in movement control. More difficult tasks, such as running or jumping might reveal differences between women with and without JH and also provoke more symptoms in the hypermobile persons. References Simmonds & Keer. Manual Therapy 2007;12:298-309. Castori et al. Am J Med Genet A, 2012;158A:2055-2070. Stacoff et al. Gait Posture 2005;21:24-38. Frigo & Crenna. Clinical Biomechanics 2009;24:236-245 Acknowledgements The study was supported by the Swiss National Science Foundation (# 13DPD6 127285) and approved by the local Ethics Committee (# 229/2008). Disclosure of Interest None Declared