The Biomechanics of Musculoskeletal Tissues during Activities of Daily Living: Dynamic Assessment Using Quantitative Transmission-Mode Ultrasound Techniques.

The measurement of musculoskeletal tissue properties and loading patterns during physical activity is important for understanding the adaptation mechanisms of tissues such as bone, tendon, and muscle tissues, particularly with injury and repair. Although the properties and loading of these connective tissues have been quantified using direct measurement techniques, these methods are highly invasive and often prevent or interfere with normal activity patterns. Indirect biomechanical methods, such as estimates based on electromyography, ultrasound, and inverse dynamics, are used more widely but are known to yield different parameter values than direct measurements. Through a series of literature searches of electronic databases, including Pubmed, Embase, Web of Science, and IEEE Explore, this paper reviews current methods used for the in vivo measurement of human musculoskeletal tissue and describes the operating principals, application, and emerging research findings gained from the use of quantitative transmission-mode ultrasound measurement techniques to non-invasively characterize human bone, tendon, and muscle properties at rest and during activities of daily living. In contrast to standard ultrasound imaging approaches, these techniques assess the interaction between ultrasound compression waves and connective tissues to provide quantifiable parameters associated with the structure, instantaneous elastic modulus, and density of tissues. By taking advantage of the physical relationship between the axial velocity of ultrasound compression waves and the instantaneous modulus of the propagation material, these techniques can also be used to estimate the in vivo loading environment of relatively superficial soft connective tissues during sports and activities of daily living. This paper highlights key findings from clinical studies in which quantitative transmission-mode ultrasound has been used to measure the properties and loading of bone, tendon, and muscle tissue during common physical activities in healthy and pathological populations.

A four-week minimalist shoe walking intervention influences foot posture and balance in young adults-a randomized controlled trial.

INTRODUCTION: Minimalist shoes (MS) are beneficial for foot health. The foot is a part of the posterior chain. It is suggested that interventions on the plantar foot sole also affect the upper segments of the body. This study aimed to investigate the local and remote effects along the posterior chain of four weeks of MS walking in recreationally active young adults. METHODS: 28 healthy participants (15 female, 13 male; 25.3 ± 5.3 years; 70.2 ± 11.9 kg; 175.0 ± 7.8 cm) were randomly assigned to a control- or intervention group. The intervention group undertook a four-week incremental MS walking program, which included 3,000 steps/day in the first week, increasing to 5,000 steps/day for the remaining three weeks. The control group walked in their preferred shoe (no MS). We assessed the following parameters in a laboratory at baseline [M1], after the four-week intervention [M2], and after a four-week wash-out period [M3]: Foot parameters (i.e., Foot Posture Index-6, Arch Rigidity Index), static single-leg stance balance, foot-, ankle-, and posterior chain range of motion, and muscle strength of the posterior chain. We fitted multiple hierarchically built mixed models to the data. RESULTS: In the MS group, the Foot Posture Index (b = -3.72, t(51) = -6.05, p < .001, [-4.94, 2.51]) and balance (b = -17.96, t(49) = -2.56, p = .01, [-31.54, 4.37]) significantly improved from M1 to M2, but not all other parameters (all p >.05). The improvements remained at M3 (Foot Posture Index: b = -1.71, t(51) = -2.73, p = .009, [-4,94,0.48]; balance: b = -15.97, t(49) = -2.25, p = .03, [-29.72, 2.21]). DISCUSSION: Walking in MS for four weeks might be advantageous for foot health of recreationally active young adults but no chronic remote effects should be expected.

Testing the Posterior Chain: Diagnostic Accuracy of the Bunkie Test versus the Isokinetic Hamstrings/Quadriceps Measurement in Patients with Self-Reported Knee Pain and Healthy Controls.

(1) Background: The isokinetic measurement (IM) of the leg muscles is well established but costly, whereas the Bunkie Test (BT) is a rarely investigated but easy-to-conduct functional test to evaluate the total posterior chain. Although the tests differ in aim and test structures, both have their justification in the assessment process. Therefore, this study evaluated the diagnostic accuracy of the BT and the IM. (2) Methods: 21 participants (9 female, 12 male; age, 26.2 ± 5.26 years; weight 73.8 ± 14.6 kg; height 176.0 ± 9.91 cm) and 21 patients (9 female, 12 male; age, 26.5 ± 5.56 years; weight, 72.6 ± 16.9 kg; height 177.0 ± 10.1 cm) with self-reported pain in the knee performed the IM and the BT. For IM, we calculated the ratio of the knee mean flexor/extensor peak torque (H/Q ratio) for 60°/s and 120°/s, and BT performance was measured in seconds. We classified the IM (<0.6 H/Q ratio) and the BT (leg difference ≥4 s) as binary results according to the literature. We calculated the sensitivity and specificity, which we compared with the Chi-Square test, and the 95% confidence intervals (CI). A p-value of ≤0.05 is considered significant. (3) Results: The sensitivity for the BT was 0.89, 95% CI [0.67, 0.99], and the specificity was 0.52 [0.30, 0.74]. For the IM, the sensitivity was 0.14 [0.03, 0.36] for 60°/s and 0.05 [0.00, 0.24] for 120°/s, and the specificity was 0.70 [0.46, 0.88] for 60°/s and 0.90 [0.68, 0.99] for 120°/s. The results of the Chi-Square tests were significant for the BT (χ2 (1) = 6.17, p = 0.01) but not for the IM (60°/s: χ2 (1) = 0.70, p = 0.40; 120°/s: χ2 (1) = 0.00, p = 0.97). (4) Conclusions: Patients were more likely to obtain a positive test result for the BT but not for the IM.

Do increasingly unstable balance devices provide a graded challenge to bipedal stance in total hip arthroplasty patients?

BACKGROUND: Progressive balance exercises are critical to early functional rehabilitation after total hip arthroplasty (THA) but little is known regarding the challenge imposed by common balance devices. RESEARCH QUESTION: Do progressively unstable balance devices provide a graded challenge to bipedal stance during early functional rehabilitation in THA patients? METHODS: Postural control was evaluated in 42 patients (age, 63.7 ± 9.6 years; height, 1.72 ± 0.08 m and body mass, 78.9 ± 14.6 kg) approximately 3 weeks (23 ± 6 days) following unilateral primary THA. Patients were divided into two groups, based on their ability to complete a 20-second unipedal stance test (UPST) on the operated limb. A lumbar mounted inertial sensor monitored center of mass (COM) displacement during bipedal balance conditions involving three balance pads of progressive stiffness and an oscillatory platform, used in isolation and in combination with the most stable balance pad. COM displacement was normalised to bipedal stance on a hard surface. Differences between conditions and patient groups were assessed using a mixed-model analysis of variance. RESULTS: Twenty patients (48%) were able to complete the UPST on their operated limb. There was a significant effect of balance condition on COM displacement during bipedal stance (F4,160 = 82.6, p < .01). COM displacement was lowest for the oscillatory platform but increased non-linearly across the three balance pads (p < .05). There was no significant difference in COM displacement between THA patients able and unable to complete the UPST. SIGNIFICANCE: Increasingly compliant balance pads provided a progressive, though nonlinear, challenge to bipedal balance control in THA patients that was greater than that of an oscillating platform and independent of the ability to stand independently on the operated limb. These findings serve as a guide for the design of progressive training programs that enhance balance in THA patients.

A Method-Comparison Study Highlighting the Disparity between Osseous- and Skin-Based Measures of Foot Mobility.

PURPOSE: This study examined the validity of standard clinical measures of arch height mobility, midfoot width mobility (MWM), and foot mobility magnitude (FMM) relative to skin-based and osseous measures derived from radiographs. METHODS: Skin-based clinical indices of foot mobility were calculated from standard, caliper-based measures of foot length, midfoot width, and dorsal arch height of the left limb of 20 healthy participants (8-71 yr) during non-weight-bearing and weight-bearing. Skin-based radiographic and osseous indices were derived from concurrent anteroposterior and lateral radiographs. Agreement between skin-based clinical and skin-based radiographic measures of foot mobility with those of osseous measures was investigated using the Bland and Altman approach. RESULTS: Foot mobility indices derived from clinical measures were significantly higher (20%-50%) than skin-based radiographic measures ( P < 0.01), which were, in turn, significantly higher (200%-250%) than osseous measures ( P < 0.01). Clinical measures demonstrated significant levels of proportional bias compared with radiographic measures of foot mobility ( P < 0.01). The contribution of osseous movement to skin-based clinical measures of mobility was highly variable between individuals, ranging between 19% and 81% for arch height mobility, between 4% and 87% for MWM, and between 14% and 75% for FMM. The limits of tolerance for clinical measures of foot mobility ranged from ±3.2 mm for MWM to ±6.6 mm for measures of FMM. The limits of tolerance for skin-based clinical and skin-based radiographic measures were generally larger than osseous movement with weight-bearing. CONCLUSIONS: Skin-based measures of foot mobility, whether clinical or radiographic methods, are not interchangeable and are poor indicators of osseous mobility. Although further research regarding the utility of osseous measures is warranted, these findings strongly caution against the use of skin-based clinical measures of foot mobility in clinical and research settings.

Frontal plane knee moment in clinical gait analysis: A systematic review on the effect of kinematic gait changes.

INTRODUCTION: The frontal plane knee moment (KAM1 and KAM2) derived from non-invasive three-dimensional gait analysis is a surrogate measure for knee joint load and of great interest in clinical and research settings. Many aspects can influence this measure either unintentionally or purposely in order to reduce the knee joint load to relieve symptoms and pain. All these aspects must be known when conducting a study or interpreting gait data for clinical decision-making. METHODS: This systematic review was registered with PROSPERO (CRD42020187038). Pubmed and Web of Science were searched for peer-reviewed, original research articles in which unshod three-dimensional gait analysis was undertaken and KAM1 and KAM2 were included as an outcome variable. Two reviewers independently screened articles for inclusion, extracted data and performed a methodological quality assessment using Downs and Black checklist. RESULTS: In total, 42 studies were included. Based on the independent variable investigated, these studies were divided into three groups: 1) gait modifications, 2) individual characteristics and 3) idiopathic orthopedic deformities. Among others, fast walking speeds (1) were found to increase KAM1; There were no sex-related differences (2) and genu valgum (3) reduces KAM1 and KAM2. CONCLUSION: While consistent use of terminology and reporting of KAM is required for meta-analysis, this review indicates that gait modifications (speed, trunk lean, step width), individual characteristics (body weight, age) and idiopathic orthopedic deformities (femoral or tibial torsion, genu valgum/varum) influence KAM magnitudes during walking. These factors should be considered by researchers when designing studies (especially of longitudinal design) or by clinicians when interpreting data for surgical and therapeutic decision-making.

Comparison between the Original- and a Standardized Version of a Physical Assessment Test for the Dorsal Chain - A Cohort-Based Cross Sectional Study.

This cohort-based cross-sectional study compares the original (OV) and a newly developed standardized version (SV) of the Bunkie Test, a physical test used to assess the dorsal chain muscles. Twenty-three participants (13 females, 10 males; median age of 26 ± 3 years) performed the test, a reverse plank, with one foot on a stool and the contralateral leg lifted. In the SV, the position of the pelvis and the foot were predefined. The test performance time (s) and surface electromyography (sEMG) signals of the dorsal chain muscles were recorded. We performed a median power frequency (MPF) analysis, using short-time Fourier transformation, and calculated the MPF/time linear regression slope. We compared the slopes of the linear regression analysis (between legs) and the performance times (between the OV and SV) with the Wilcoxon test. Performance times did not differ between SV and OV for either the dominant (p = 0.28) or non-dominant leg (p = 0.08). Linear regression analysis revealed a negative slope for the muscles of the tested leg and contralateral erector spinae, with a significant difference between the biceps femoris of the tested (-0.91 ± 1.08) and contralateral leg (0.01 ± 1.62) in the SV (p = 0.004). The sEMG showed a clearer pattern in the SV than in the OV. Hence, we recommend using the SV to assess the structures of the dorsal chain of the tested leg and contralateral back.

Myofascial Treatment Techniques on the Plantar Surface Influence Functional Performance in the Dorsal Kinetic Chain.

Prior studies have shown that self- and manual massage (SMM) increases flexibility in non-adjacent body areas. It is unclear whether this also influences performance in terms of force generation. Therefore, this study investigated the effect of SMM on the plantar surface on performance in the dorsal kinetic chain. Seventeen young participants took part in this within-subject non-randomized controlled study. SMM was applied on the plantar surface of the dominant leg, but not on the non-dominant leg. A functional performance test of the dorsal kinetic chain, the Bunkie Test, was conducted before and after the intervention. We measured the performance in seconds for the so-called posterior power line (PPL) and the posterior stabilizing line (PSL). The performance of the dominant leg in the Bunkie Test decreased significantly by 17.2% from (mean ± SD) 33.1 ± 9.9 s to 27.4 ± 11.1 s for the PPL and by 16.3% from 27.6 ± 9.8 s to 23.1 ± 11.7 s for the PSL. This is in contrast to the non-dominant leg where performance increased significantly by 5.1% from 29.7 ± 9.6 s to 31.1 ± 8.9 s for the PPL and by 3.1% from 25.7 ± 1.5 s to 26.5 ± 1.7 s for the PSL. SMM interventions on the plantar surface might influence the performance in the dorsal kinetic chain.

Effects of idiopathic flatfoot deformity on knee adduction moments during walking.

INTRODUCTION: Flatfoot deformity is commonly characterized by a subtalar valgus, a low medial longitudinal arch, and abduction of the forefoot. Although flatfoot deformity has been associated with lower first (KAM1) and second (KAM2) peak knee adduction moments during walking, the biomechanical connection remains unknown. RESEARCH QUESTION: We hypothesized that hindfoot eversion, lateral calcaneal shift correlate with KAM1 and forefoot abduction and arch height with KAM2, due to the lateralization of the ground reaction force vector resulting from shifted heel and forefoot in flatfoot deformity. METHODS: Gait data from 103 children with flatfoot deformity who underwent three-dimensional gait analysis with the Oxford Foot Model were retrospectively included. Children with knee varus/valgus, in- and out-toeing were excluded. Fifteen healthy children with a rectus foot type were also collected from the database. Lateral calcaneal shift was defined as the distance between the projection of the ankle joint center onto the calcaneal axis and the midpoint of the calcaneal axis formed by the medial and lateral calcaneal markers. A subgroup of children with idiopathic flatfoot deformity that had received corrective surgery was also identified. Statistical analysis included Pearson's correlations and independent and paired t-tests (α < .05). RESULTS: When compared to a norm cohort, flatfooted children had significant lower KAM1 and KAM2 (t-test, P < .001). Lateral calcaneal shift correlated with KAM1 and KAM2 (r = 0.42, p < .001 and r = 0.32, P < .001, respectively). Arch height correlated with KAM2 (r = 0.23, p = 0.017). KAM1 and KAM2 normalized after surgery and the change in KAM1 correlated with the change in lateral calcaneal shift for children who underwent corrective surgery. SIGNIFICANCE: Lateral calcaneal shift explains the reduction of KAM1 by lateralization of the point of force application in flatfooted children. It is recommended to consider the lateral calcaneal shift when investigating KAM in gait analysis research.

Transmission-Mode Ultrasound for Monitoring the Instantaneous Elastic Modulus of the Achilles Tendon During Unilateral Submaximal Vertical Hopping.

Submaximal vertical hopping capitalizes on the strain energy storage-recovery mechanism associated with the stretch-shortening cycle and is emerging as an important component of progressive rehabilitation protocols in Achilles tendon injury and a determinant of readiness to return to sport. This study explored the reliability of transmission mode ultrasound in quantifying the instantaneous modulus of elasticity of human Achilles tendon during repetitive submaximal hopping. A custom-built ultrasound transmission device, consisting of a 1 MHz broadband emitter and four regularly spaced receivers, was used to measure the axial velocity of ultrasound in the Achilles tendon of six healthy young adults (mean ± SD; age 26 ± 5 years; height 1.78 ± 0.11 m; weight 79.8 ± 13.6 kg) during steady-state unilateral hopping (2.5 Hz) on a piezoelectric force plate. Vertical ground reaction force and lower limb joint kinematics were simultaneously recorded. The potential sensitivity of the technique was further explored in subset of healthy participants (n = 3) that hopped at a slower rate (1.8 Hz) and a patient who had undergone Achilles tendon rupture-repair (2.5 Hz). Reliability was estimated using the mean-within subject coefficient of variation calculated at each point during the ground-contact phase of hopping, while cross-correlations were used to explore the coordination between lower limb kinematics ground reaction forces and ultrasound velocity in the Achilles tendon. Axial velocity of ultrasound in the Achilles tendon was highly reproducible during hopping, with the mean within-subject coefficient of variation ranging between 0.1 and 2.0% across participants. Ultrasound velocity decreased immediately following touch down (-19 ± 13 ms-1), before increasing by 197 ± 81 ms-1, on average, to peak at 2230 ± 87 ms-1 at 67 ± 3% of ground contact phase in healthy participants. Cross-correlation analysis revealed that ultrasound velocity in the Achilles tendon during hopping was strongly associated with knee (mean r = 0.98, range 0.95-1.00) rather than ankle (mean r = 0.67, range 0.35-0.79) joint motion. Ultrasound velocity was sensitive to changes in hopping frequency in healthy adults and in the surgically repaired Achilles tendon was characterized by a similar peak velocity (2283 ± 13 ms-1) but the change in ultrasound velocity (447 ± 21 ms-1) was approximately two fold that of healthy participants (197 ± 81 ms-1). Although further research is required, the technique can be used to reliably monitor ultrasound velocity in the Achilles tendon during hopping, can detect changes in the instantaneous elastic modulus of tendon with variation in hopping frequency and tendon pathology and ultimately may provide further insights into the stretch-shortening cycle and aid clinical decision concerning tendon rehabilitation protocols and readiness to return to sport.

Limb movement, coordination and muscle activity during a cross-coordination movement on a stable and unstable surface.

BACKGROUND: At a clinical level, the intensity of dynamic balance tasks incorporating cross-coordination movements (CCM) is typically progressed by changing the stability of the support surface on which the movement is undertaken. However, biomechanical changes in CCMs performed on stable and unstable surfaces have not yet been quantified. RESEARCH QUESTION: Do movement patterns, muscle activity, coordination strategies, knee joint loading and center of mass (CoM) movement differ during a CCM performed on stable and unstable surfaces? METHODS: Motion analysis was used to monitor limb kinematics and surface electromyography to analyze supporting leg muscle activity in sixteen healthy athletes during a single-limb support task involving a cyclic CCM on a stable and unstable surface. Angle-angle plots were used to explore coordination strategies in sagittal movement of the hip and shoulder, while differences in kinematics and muscle activity between stable and unstable conditions were evaluated using dependent t-tests (α-level = 0.05). RESULTS: CCMs on an unstable surface were performed at a slower speed (p < .05), with a more flexed posture of the support knee (p < .05) and ankle (p < .05) and resulted in reduced hip and shoulder movement of the swing limbs (p < .05). Instability increased activation of selected muscles of the ankle and knee (p < .05), resulted in a two-fold increase in the peak knee adduction moment (p < .05), and was accompanied by greater CoM movement (p < .05). Three coordination patterns of the swing limbs observed when performing CCM on a stable surface, which were mostly preserved on the unstable surface. SIGNIFICANCE: Despite adopting several stabilization strategies, CCM undertaken on an unstable surface still evoked greater excursion of the center of mass and, as such, presented a greater challenge to sensorimotor control. Adding instability in form of a swinging platform provides progression of dynamic balance CCM difficulty in an athletic population.

Compensatory mechanisms in children with idiopathic lower extremity internal rotational malalignment during walking and running.

BACKGROUND: Noticeable in-toeing gait is present in most children with internal rotational malalignment and often a reason to consult an orthopedic specialist. The risk of tripping may be higher for these patients. RESEARCH QUESTION: The aim of this study was to determine compensatory mechanisms adopted by children with internal rotational deformities to avoid tripping and falling during walking and running. METHODS: Sixty-nine patients between 5-18 years with idiopathic internal rotational malalignment were retrospectively included and subdivided into three groups: 18 patients with internal tibial torsion (ITT), 25 patients with internal femoral torsion (ITF) and 26 patients with both (ITB). Twenty-two typically developing age-matched children (TD) were analyzed for comparison. Three-dimensional gait data were evaluated. ANOVA's on two factors, group (ITT, ITF, ITB, TD) and movement (walking, running) with post-hoc t-tests were used to identify significant differences between groups. RESULTS: All groups had significantly greater step width than TD during walking (P ≤ .002) and all torsional groups had significantly greater step width during running (P ≤ .001). Similarly, all torsional groups showed greater peak ankle dorsiflexion in swing during running than TD (P ≤ .006). Only the ITT group showed significantly greater external hip rotation than TD. When compared to TD, the ITF and ITB group had a significantly lower hip abduction moment in stance during running, but not for walking (P ≤ .032). SIGNIFICANCE: Compensatory mechanisms in children with internal rotational deformities were mostly dependent on the location of rotational malalignment. All children with internal rotational malalignment had greater ankle dorsiflexion and greater step width during running. Especially in active patients, this greater ankle dorsiflexion during running may result in overuse of the ankle dorsiflexor muscles, while greater step width may have beneficial effects in normalizing knee adduction moments.

Variability in trunk and pelvic movement of transfemoral amputees using a C-leg system compared to healthy controls.

OBJECTIVE: Gait variability is a measure of gait disturbance, and therefore constitutes a useful parameter for gait assessment as well as planning of therapeutic and medical interventions. To date, variability during walking has not been adequately analyzed in amputees. The aim of this examination was to evaluate trunk and pelvic movement variability in transfemoral amputees. The effect of different types of walking surfaces on variability in trunk and pelvic movement was also studied. METHOD: This prospective clinical examination compares 20 transfemoral amputees (17 ♂, 42 ±â€¯16 years; 3 ♀, 48 ±â€¯3 years) with a group of 20 age and mass matched healthy controls regarding the extent of variability in trunk and pelvic movement. Kinematic data of trunk and pelvic movement during walking on level, uneven ground and slope was captured by eight infrared cameras (Vicon Nexus ™, Oxford, UK). Variability in trunk and pelvic movement was analyzed. Univariate ANCOVA and ANOVA with repeated measures and post hoc tests were used for statistical comparison. Fall history was retrospectively collected from medical history to assess the association between falls and variability in trunk and pelvic movement. RESULTS: Trunk and pelvic movement variability in amputees was significantly higher during walking on uneven ground and slope compared to healthy controls (p ≤ 0.05). Variability in trunk and pelvic movement was increased during walking on uneven ground and slope compared to even ground for both groups (p ≤ 0.05). CONCLUSION: Amputees showed increased trunk and pelvic movement variability during walking on uneven ground and slope, indicating an affected gait pattern in comparison to healthy controls. Therefore, trunk and pelvic movement variability could be a potential marker for gait quality with diagnostic implications.

Relation between the amount of daily activity and gait quality in transfemoral amputees.

Gait variability is often associated with reduced coordination and increased instability during walking. Especially for patients with musculoskeletal conditions, variability in gait might be associated with the level of daily activity. Therefore, this study examines kinematic variability during walking and the association with daily activity in patients with transfemoral amputation. Therefore, 15 transfemoral amputees, using the C-leg prosthesis of Otto Bock, between 18 and 65 years were recruited during their hospital stay. All patients were able to walk without crutches in everyday life and were familiar with walking using the C-leg system. Gait parameters and data of variability were captured during walking in a gait laboratory by eight infrared cameras (Vicon). Daily activity was assessed using a three-dimensional acceleration sensor of VitaMove. Patients showed variability from 0.84° up to 1.96° in frontal pelvis motion and from 0.9° up to 4.02° in trunk obliquity. The results show a significant correlation between activity and variability in trunk (r = -0.58; P ≤ 0.05) and pelvis (r = -0.63; P ≤ 0.01) as well as gait velocity (r = 0.6; P ≤ 0.05). However, kinematic variability and gait velocity are not related to each other. In conclusion, the results show that kinematic gait variability is associated with the extent of activity and therefore presents an important parameter for assessing amputees' gait quality and daily activity.

Effects of core stability training on throwing velocity and core strength in female handball players.

BACKGROUND: This study investigated the effect of a six-week in-season core stability training (CST) intervention on maximal throwing velocity and core strength parameters. METHODS: Twenty female handball players (23.4±4.4 years, 168.4±3.5 cm, and 66.9±9.2 kg) were randomized into a CST intervention group (N.=10) and a control group (CON, N.=10). Throwing velocity, maximal isometric strength (MIS) and endurance strength of the ventral, dorsal and lateral core muscle chains were measured before and after progressive, six-week core stability training in the CST group. RESULTS: Core endurance of both lateral core muscle chains (LR: F=7.03, P=0.017; LL: F=6.31, P=0.022;) and MIS of the left lateral core muscle chain (LL: F=7.08, P=0.019) was significantly improved in CST compared to CON group after 6 weeks. Additionally, CST group significantly increased MIS of the lateral right core muscles (21%, P=0.042) and the ventral core endurance (35%, P=0.016) compared to baseline. Although both groups significantly increased throwing velocity of the jump throw after the intervention (CST 12%, P=0.001; CON 8%, P=0.009), throwing velocity of the standing throw remained unchanged. CONCLUSIONS: A six-week CST intervention effectively increased the isometric strength and endurance of selected core muscles but did not significantly enhance throwing velocity compared to standard training.

Differences in pain intensity in anti- and pro-nociceptive pain profile subgroups in patients with knee osteoarthritis.

AIM: Facilitated temporal summation is one component of central sensitization. The aim of this exploratory study was to classify pro-, eu- and antinociceptive subgroups based on wind-up ratio cut-off scores in patients with knee osteoarthritis (OA). PATIENTS & METHODS:  A total of 56 patients with knee OA met the inclusion criteria. Temporal summation was measured and wind-up ratio was calculated. Reference values of 180 healthy subjects were used to define wind-up ratio cut-off scores. RESULTS: Twenty-seven percent of patients showed a pro-nociceptive pain profile. Sixteen percent of patients showed an anti-nociceptive pain profile. A eu-nociceptive pain profile was present in 57% of patients. CONCLUSION: Central pain sensitization was present in approximately a third of knee OA patients. The results should be confirmed in larger studies.

Predictors of chronic pain following total knee replacement in females and males: an exploratory study.

AIM: This study explored whether nociceptive (NS) and autonomic nervous system (ANS) dysregulation and psychological distress were predictive of pain 6 months after primary total knee replacement. PATIENTS & METHODS: ANS and NS regulation, psychological distress and self-reported pain, stiffness and function were evaluated preoperatively in 56 patients. Pain severity measured 6 months after surgery was used as the primary outcome in an analysis of covariance model. RESULTS: The data of 47 patients (85.5%) could be analyzed. Postoperative pain severity 6 months after surgery was significantly associated with reduced heart rate variability and tended to be related to a lower conditioned pain modulation effect, but the latter only in females. CONCLUSION: Due to the small sample size the results must be interpreted with caution. A dysregulation of ANS and NS may be predictive of pain severity 6 months after total knee replacement. The impact of the conditioned pain modulation effect could be sex specific.

Achilles Tendon Load is Progressively Increased with Reductions in Walking Speed.

INTRODUCTION: Achilles tendon rehabilitation protocols commonly recommend a gradual increase in walking speed to progressively intensify tendon loading. This study used transmission-mode ultrasound to evaluate the influence of walking speed on loading of the human Achilles tendon in vivo. METHODS: Axial transmission speed of ultrasound was measured in the right Achilles tendon of 33 adults (mean ± SD: age, 29 ± 3 yr; height, 1.725 ± 0.069 m; weight, 71.4 ± 19.9 kg) during unshod, steady-state treadmill walking at three speeds (slow, 0.85 ± 0.12 ms; preferred, 1.10 ± 0.13 m·s; fast, 1.35 ± 0.20 m·s). Ankle kinematics, spatiotemporal gait parameters and vertical ground reaction force were simultaneously recorded. Statistical comparisons were made using repeated-measures ANOVA models. RESULTS: Increasing walking speed was associated with higher cadence, longer step length, shorter stance duration, greater ankle plantarflexion, higher vertical ground reaction force peaks, and a greater loading rate (P < 0.05). Maximum (F1,38 = 7.38, P < 0.05) and minimum (F1,46 = 8.95, P < 0.05) ultrasound transmission velocities in the Achilles tendon were significantly lower (16-23 m·s) during the stance but not swing phase of gait, with each increase in walking speed. CONCLUSIONS: Despite higher vertical ground reaction forces and greater ankle plantarflexion, increasing walking speed resulted in a reduction in the axial transmission velocity of ultrasound in the Achilles tendon; indicating a speed-dependent reduction in tensile load within the triceps surae muscle-tendon unit during walking. These findings question the rationale for current progressive loading protocols involving the Achilles tendon, in which reduced walking speeds are advocated early in the course of treatment to lower Achilles tendon loads.

Muscle activity of leg muscles during unipedal stance on therapy devices with different stability properties.

OBJECTIVES: To test the hypotheses that less stable therapy devices require greater muscle activity and that lower leg muscles will have greater increases in muscle activity with less stable therapy devices than upper leg muscles. DESIGN: Cross-sectional laboratory study. SETTING: Laboratory setting. PARTICIPANTS: Twenty-five healthy subjects. MAIN OUTCOME MEASURES: Electromyographic activity of four lower (gastrocnemius medialis, soleus, tibialis anterior, peroneus longus) and four upper leg muscles (vastus medialis and lateralis, biceps femoris, semitendinosus) during unipedal quiet barefoot stance on the dominant leg on a flat rigid surface and on five therapy devices with varying stability properties. RESULTS: Muscle activity during unipedal stance differed significantly between therapy devices (P < 0.001). The order from lowest to highest relative muscle activity matched the order from most to least stable therapy device. There was no significant interaction between muscle location (lower versus upper leg) and therapy device (P = 0.985). Magnitudes of additional relative muscle activity for the respective therapy devices differed substantially among lower extremity muscles. CONCLUSIONS: The therapy devices offer a progressive increase in training intensity, and thus may be useful for incremental training programs in physiotherapeutic practice and sports training programs.

Improvement of walking speed and gait symmetry in older patients after hip arthroplasty: a prospective cohort study.

BACKGROUND: Retraining walking in patients after hip or knee arthroplasty is an important component of rehabilitation especially in older persons whose social interactions are influenced by their level of mobility. The objective of this study was to test the effect of an intensive inpatient rehabilitation program on walking speed and gait symmetry in patients after hip arthroplasty (THA) using inertial sensor technology. METHODS: Twenty-nine patients undergoing a 4-week inpatient rehabilitation program following THA and 30 age-matched healthy subjects participated in this study. Walking speed and gait symmetry parameters were measured using inertial sensor device for standardized walking trials (2*20.3 m in a gym) at their self-selected normal and fast walking speeds on postoperative days 15, 21, and 27 in patients and in a single session in control subjects. Walking speed was measured using timing lights. Gait symmetry was determined using autocorrelation calculation of the cranio-caudal (CC) acceleration signals from an inertial sensor placed at the lower spine. RESULTS: Walking speed and gait symmetry improved from postoperative days 15-27 (speed, female: 3.2 and 4.5 m/s; male: 4.2 and 5.2 m/s; autocorrelation, female: 0.77 and 0.81; male: 0.70 and 0.79; P <0.001 for all). After the 4-week rehabilitation program, walking speed and gait symmetry were still lower than those in control subjects (speed, female 4.5 m/s vs. 5.7 m/s; male: 5.2 m/s vs. 5.3 m/s; autocorrelation, female: 0.81 vs. 0.88; male: 0.79 vs. 0.90; P <0.001 for all). CONCLUSIONS: While patients with THA improved their walking capacity during a 4-week inpatient rehabilitation program, subsequent intensive gait training is warranted for achieving normal gait symmetry. Inertial sensor technology may be a useful tool for evaluating the rehabilitation process during the post-inpatient period.