Variations in neuromuscular activity of thigh muscles during whole-body vibration in consideration of different biomechanical variables

The intention of this study was to systematically analyze the impact of biomechanical variables in terms of different vibration frequencies, amplitudes and knee angles on quadriceps femoris and hamstring activity during exposure to whole-body vibration (WBV). 51 healthy men and women (age 55 ± 8 years) voluntary participated in the study and were randomly allocated to five different vibration-frequency groups. Each subject performed 9 static squat positions (3 amplitudes x 3 knee angles) on a side alternating vibration platform. Surface electromyography (EMG) was used to record the neuromuscular activity of the quadriceps femoris and hamstring muscles. Maximal voluntary contractions (MVCs) were performed prior to the measurements to normalize the EMG signals. A three-way mixed ANOVA was performed to analyze the different effects of the biomechanical variables on muscle activity. Depending on the biomechanical variables, EMG muscle activity ranged between 18.2 and 74.1 % MVC in the quadriceps femoris and between 5.2 and 27. 3 % MVC in the hamstrings during WBV. The highest levels of muscle activation were found at high frequencies and large amplitudes. Especially in the quadriceps femoris muscle, a WBV frequency of 30 Hz led to a significant increase in muscle activity compared to the other tested frequencies. However, it seems that knee angle is only relevant for the quadriceps femoris muscle. The results of this study should give more information for developing individual training protocols for WBV treatment in different practical applications. Key PointsWBV leads to a higher muscle activity of the quadriceps femoris than of the hamstrings.The maximum levels of muscle activity were significantly reached at high amplitude and high frequency.The knee angle only significantly affects the quadriceps femoris.Certain combinations of the biomechanical variables have similar effects on the level of muscle activity.

Impact of total hip arthroplasty on pain, walking ability, and cardiovascular fitness

We tested the hypothesis that total hip arthroplasty (THA) patients have less pain and are able to walk longer post-operatively than pre-operatively, and that THA patients before and after have higher heart rates and compromised gas exchange determinants at rest and following exercise compared to healthy subjects with a post-operative improvement. Fifty-two patients completed questionnaires and an incremental walking stress test pre-operatively and 6-months after THA. Twenty-four age-matched control subjects completed the same stress test. Fifty-one patients had less pain 6-months after THA compared to pre-operative levels. Forty-three patients showed an improvement of at least one walking duration category. Patients had compromised cardiovascular fitness compared to the control group with a tendency to improve after THA. Hence, 6-months following THA, deficits exist other than reduced strength as reported in the literature. Prior to THA, the ability to walk longer is compromised by pain and not by poor cardiovascular fitness. Studies on specific rehabilitation programs of varying intensities may demonstrate opportunities to improve the cardiovascular fitness of this population.

Deficits 10-years after Achilles tendon repair

The purpose of this study was to determine the long-term impact of surgical repair and subsequent 6-week immobilization of an Achilles tendon rupture on muscle strength, muscle strength endurance and muscle activity. 63 patients participated in this study on average 10.8 ± 3.4 years after surgically repaired Achilles tendon rupture and short-term immobilization. Clinical function was assessed and muscle strength, strength endurance and muscle activity were measured using a dynamometer and electromyography. Ankle ROM, heel height during heel-raise tests and calf circumference were smaller on the injured than on the contralateral side. Ankle torques during the concentric dorsiflexion tasks at 60 °/sec and 180 °/sec and ankle torques during the eccentric plantarflexion task and during the concentric plantarflexion task at 60 °/sec for the injured leg were significantly lower than those for the contralateral leg. The total work during a plantarflexion exercise at 180 °/sec was 14.9% lower in the injured compared to the contralateral leg (p < 0.001). Muscle activity for the gastrocnemius muscle during dorsiflexion tasks was significantly higher in the injured than in the contralateral limb. Limited ankle joint ROM and increased muscle activity in the injured leg suggest compensatory mechanisms to account for differences in muscle morphology and physiology caused by the injury.

Comparison of distinctive gait variables using two different biomechanical models for knee joint kinematics in subjects with knee osteoarthritis and healthy controls

BACKGROUND

Gait analysis is an important instrument in clinical research and results should be objective. The purpose of this study was to quantify clinical outcomes of two biomechanical models with different anatomical coordinate systems and angle decomposition strategies for knee joint kinematics.

METHODS

The study was designed to compare a functional approach and a predictive approach with a single comprehensive marker set. 10 healthy subjects and 12 subjects with knee osteoarthritis were analysed. Distinctive gait variables were averaged across five trials. Agreement between methods was illustrated with the so-called levels of agreement. Differences between models were quantified using a paired t-test or Wilcoxon-Signed Rank test in case of non-normality (Shapiro-Wilk test). Unpaired t-tests/Wilcoxon tests were used to compare gait variables between healthy subjects and subjects with knee osteoarthritis, and to examine whether statistical analysis of this comparison would yield different data interpretations when using different models.

FINDINGS

Outcome variables differed between the functional and predictive approaches in the sagittal plane (0.1-3.1°), and transverse plane (1.0-3.7°). With respect to the range of motion in the given movement plane, variables in the sagittal plane of the knee were more consistent between methods. The functional approach was more sensitive for detecting differences between groups for sagittal plane kinematics. Statistical analysis for transverse plane kinematics differed substantially between models.

INTERPRETATION

Sensitivity to detect differences of kinematic data between population groups can vary between biomechanical models. Rotational gait variables are inconsistent between models and should not be used as clinical outcome variables in daily routine.

The influence of Nordic Walking training on sit-to-stand transfer in Parkinson patients

Neurodegenerative processes in Parkinson's disease (PD) particularly affect activities of daily living (ADL). Problems of patients with PD in sit-to-stand (STS) performance have been verified before, but not the effects of training on biomechanical measures of STS function. This pilot study aimed to analyse effects of 12 weeks of Nordic Walking training and severity of PD: healthy controls (CO), least (UPDRS A) and more severe (UPDRS B) affected PA on selected functional outcome measures. We expected improvements in PD similar to CO, with better performance of the unstable second phase and faster execution of the entire movement with higher velocities of centre of gravity (COG). 3D kinematics of 22 PD and 18 CO subjects before and after training, were recorded using a motion analysis system (Vicon, Oxford). We compared five outcome measures for STS in 11 PD and 11 CO, matched according to age, gender, height, and weight. Effects of Nordic Walking training were not statistically significant but indicated different patterns which depended on the values of patient's UPDRS score (part III, motor functions). Time required for STS performance increased and horizontal and vertical velocity of COG decreased in UPDRS B, which could be due to progression of PD during the training period. In contrast, UPDRS A showed similar effects as CO. The effects of Nordic Walking as an easy, economic and low-risk intervention on STS in PD depend on the degree of PD. Our findings may help scientists, patients, and therapists to adjust sport-physiological interventions.

Reliability and validity of 4D rasterstereography under dynamic conditions

Purpose of this study was to evaluate the reliability and validity of 4D rasterstereography under dynamic conditions. Therefore simulated anatomical fixed points on a wooden plate were measured during different movements. Seven different motion patterns in all three angles of space were evaluated. The simulated parameter trunk length was measured with an accuracy of 3.58 mm (SD±3.29 mm) and the dimple distance was detected with an accuracy of 0.88 mm (SD±1.04 mm). With this rasterstereographic prototype it is possible to examine dynamically the spinal posture with adequate accuracy.

Sex-related differences in foot shape of adult Caucasians--a follow-up study focusing on long and short feet

The study's purpose was to substantiate findings on sex-related differences in foot morphology focusing on fringe sizes. Altogether, 287 Caucasian adults with long or short feet were scanned. Data were analysed together with data from 847 subjects from a previous study with comparable inclusion criteria and anthropometric data by: (1)comparing absolute measures within 237-277 mm foot length (FL); (2) comparing averaged measures across sizes in % of foot length for 203-323 mm FL; (3) reclassifying the additional subjects into a previously defined foot type classification. Male feet were wider and higher for the same FL. Averaged across sizes, no relevant differences between sexes were found for widths and heights. Slender or flat-pointed foot types were more common in longer feet, shorter feet tended to be bigger. Definitions for 'long' and 'short' are sex-related with an offset of three shoe sizes (EU). Results of this follow-up study on long and short feet can substantiate previous findings mainly described for the most common sizes. STATEMENT OF RELEVANCE: Improper footwear can cause pain and injury and proper fit is a major criterion for shoe buyers. Knowledge about sex-related differences in foot shape is important for shoe design. This study supplements the field of knowledge for very small and large feet.

[Relation between pelvis malposition and functional knee pain by long distance running]

PURPOSE

During endurance run knee problems often appear. This study wants to show the connection between a one- sided malposition of the pelvis and knee joint pain during endurance running.

METHOD

We tested endurance runners which had pelvis malposition and knee pain. Therefore 100 athletes were tested, 50 with knee pain and 50 without knee pain. Manual examination and clinical instruments were used for examination of sacroiliac joints for measurement of vertical distances between spinae iliacae anteriores superiores. Collected data were analyzed by appropriate statistical methods.

RESULTS

The results show that there is a connection between a one- sided pelvic malposition and knee pain during endurance running. These relations are probably realized by changes in lower extremity dysfunction as a result of pathological chains. The one sided pelvis malposition was in the control group significant higher (0.9 ± 0.4 cm) than in the control group (0.3 ± 0.2 cm).

CONCLUSION

There is a correlation between knee pain and os coxae malposition. (It is necessary in examine and treat the the cause- and effect chain to prevent injuries).

The rasterstereographic-dynamic analysis of posture in adolescents using a modified Matthiass test

The Matthiass posture test is a clinical test to detect posture changes in children and adolescents. Aim of this study was to objectify this test using a dynamic rasterstereographic measuring device. We examined 31 healthy athletes during a modified Matthiass test with a dynamic rasterstereographic measuring system. Hereby the trunk inclination, kyphosis and lordosis angle were measured. The trunk inclination decreased by about 50% of the basic value just by raising the arms. Additional weight loads of only 5% body weight (bw) resulted in significant changes of the posture (lordosis and kyphosis angle) during this test. With this rasterstereographic measuring device it seems to be possible to determine spinal posture changes under dynamic conditions. The results suggest that additional weights of 5% bw during the Matthias-test are enough to create significant deviations in posture parameters, even in healthy subjects.

Effects of a sensory-motor exercise program for older adults with osteoarthritis or prosthesis of the hip using measurements made by the Posturomed oscillatory platform

OBJECTIVES

To assess changes in balance capacities after a 12-week sensory-motor training program for older adults with osteoarthritis or prosthesis of the hip.

BACKGROUND

Sensory-motor training is recommended to help aging adults with osteoarthritis maintain activity, avoid injurious falls, and improve functioning. Up to now, however, there has been no standard training protocol for sensory-motor training.

METHODS AND MEASURES

Thirty-five participants in a hip exercise group who had a mean age of 58 years (SD 12) were quasi-randomized into a training group (TG) and a control group (CG) by the month they applied for the Hip School program. The TG performed balance exercises using balance pads and received Hip School training once a week. The CG did not receive any training intervention. Balance was measured by recording center-of-pressure excursion while participants were in 1-legged stance on the oscillatory Posturomed platform. Outcome measures were the total path of center of pressure on the platform during balance recovery and the percentage of failed attempts.

RESULTS

The TG had a lower percentage of failed attempts (TG 5%, CG 18%, P = .001) and required fewer balance recovery movements to maintain balance (TG: mean [SD] measurement is 59 [36] mm; CG: 96 [68] mm, P = .036] after completing the 12-week training program. After the training period, participants in the TG compensated better for perturbations in the nondisplaced medial-lateral (ML) direction (pretest [SD] measurement was 48 [18] mm; posttest, 36 [14] mm; P= .001].

CONCLUSIONS

Participants could successfully cope with more disturbances and improved their reactions to sudden displacements after training intervention. This exercise setting improves balance abilities and should be included in Hip School programs for patients with osteoarthritis.

Kinematic analysis of runners with achilles mid-portion tendinopathy

BACKGROUND

Despite anecdotal evidence linking overpronation to the onset of Achilles tendinopathy (AT), there is little conclusive evidence of a particular movement pattern of the lower extremity associated with this injury. Therefore, the objective of the present study was to observe differences in the kinematic profiles of healthy runners (CON) and runners with mid-portion Achilles tendinopathy (ATG).

MATERIALS AND METHODS

In this cross-sectional analysis, 48 male height and weight matched subjects were invited to participate: 27 with mid-portion Achilles tendon pain and 21 asymptomatic controls. Subjects underwent lower extremity clinical examination, then ran barefoot for 10-trials at a self-selected pace. A 3D motion capture system analysed tri-plane kinematic data for the lower extremity.

RESULTS

The ATG displayed significantly greater sub-talar joint eversion displacement during mid-stance of the running gait (13 +/- 3 degrees vs. 11 +/- 3 degrees; p = 0.04). Trends were observed such that the ATG showed lower peak dorsiflexion velocity (300 +/- 39 degrees/s vs. 330 +/- 59 degrees/s; p = 0.08) and greater overall frontal plane ankle joint range of motion (45 degrees +/- 7 vs. 41 degrees +/- 7; p = 0.09).

CONCLUSION

We found an increase in eversion displacement of the sub-talar joint in runners with Achilles mid-portion tendinopathy. Based on the findings from this study, there is evidence that devices used to control sub-talar eversion may be warranted in patients with Achilles mid-portion tendinopathy who demonstrate over-pronation during mid-stance of the running gait.

A new approach to children's footwear based on foot type classification

Current shoe designs do not allow for the comprehensive 3-D foot shape, which means they are unable to reproduce the wide variability in foot morphology. Therefore, the purpose of this study was to capture these variations of children's feet by classifying them into groups (types) and thereby provide a basis for their implementation in the design of children's shoes. The feet of 2867 German children were measured using a 3-D foot scanner. Cluster analysis was then applied to classify the feet into three different foot types. The characteristics of these foot types differ regarding their volume and forefoot shape both within and between shoe sizes. This new approach is in clear contrast to previous systems, since it captures the variability of foot morphology in a more comprehensive way by using a foot typing system and therefore paves the way for the unimpaired development of children's feet. Previous shoe systems do not allow for the wide variations in foot morphology. A new approach was developed regarding different morphological foot types based on 3-D measurements relevant in shoe construction. This can be directly applied to create specific designs for children's shoes.

The influence of matching populations on kinematic and kinetic variables in runners with iliotibial band syndrome

The purpose of this study was to assess how participant matching influences biomechanical variables when comparing healthy runners and runners with iliotibial band syndrome (ITBS). We examined 52 healthy runners (CO) and 18 with ITBS, using three-dimensional kinematics and pressure distribution. The study population was matched in three ways and compared with the biomechanical findings: ITBS versus CO I (unmatched), ITBS versus CO II (matched to gender) and ITBS versus CO III (matched to gender height, and weight). The final number of participants in each group was n = 18. The kinematic variables showed a dependency on the matching process. The largest statistically significant differences (after Bonferroni adjustment) in the frontal and transverse planes were between ITBS and CO III (p = .008). Pressure measurements were also dependent on the matching process, with decreasing and nonsignificant differences (p = .006) between ITBS and CO after refining the process (ITBS vs. CO III). The results of this study and the necessity of matching seem to be plausible (lever arms, different running styles). Data matching is important for understanding overuse injuries in running.

Sex-related differences in foot shape

The purpose of the study was to investigate sex-related differences in foot morphology. In total, 847 subjects were scanned using a 3-D-footscanner. Three different analysis methods were used: (1) comparisons were made for absolute foot measures within 250-270 mm foot length (FL); (2) and for averaged measures (% FL) across all sizes; (3) the feet were then classified using a cluster analysis. Within 250-270 mm FL, male feet were wider and higher (mean differences (MD) 1.3-5.9 mm). No relevant sex-related differences could be found in the comparison of averaged measures (MD 0.3-0.6% FL). Foot types were categorised into voluminous, flat-pointed and slender. Shorter feet were more often voluminous, longer feet were more likely to be narrow and flat. However, the definition of 'short' and 'long' was sex-related; thus, allometry of foot measures was different. For shoe design, measures should be derived for each size and sex separately. Different foot types should be considered to account for the variety in foot shape. Improper footwear can cause foot pain and deformity. Therefore, knowledge of sex-related differences in foot measures is important to assist proper shoe fit in both men and women. The present study supplements the field of knowledge within this context with recommendations for the manufacturing of shoes.

Foot morphology of normal, underweight and overweight children

OBJECTIVE

Due to the fact that there is a global increase in obesity, knowledge about the impact of obesity on the development of a child's foot is of great importance for orthopaedic and paediatric physicians with regard to prevention, clinical treatment and management. Therefore, the purpose of this study was to investigate the influence of body mass on the development of a child's foot based on a foot type classification.

METHODS

The feet of 1450 boys and 1437 girls aged 2-14 years were measured using a three-dimensional (3D) foot scanner (Pedus, Human Solutions Inc., Germany) in a bipedal upright position. Twelve relevant 3D foot measures were recorded, as well as the children's age, gender, height and mass. Factor analysis of principal components was used to obtain a smaller number of independent and standardized variables. The variables were used for cluster analysis to classify the children's feet.

RESULTS

Five foot types were identified: flat, robust, slender, short and long feet. There were significant differences among foot types with respect to the children's body mass index. Normal weight children displayed an almost equal distribution of all foot types throughout childhood. Flat and robust feet were more common in overweight children, whereas underweight children showed more slender and long feet.

CONCLUSION

The influence of excess, as well as deficient mass could be verified for the comprehensive foot morphology based on a foot type classification. Subsequently, foot discomfort as a result of various musculoskeletal disorders may develop. In turn, this might keep the children from being active and therefore reinforce the risk of developing obesity. However, there is still a lack of information regarding these relationships, which needs to be determined. This knowledge may help prevent orthopaedic foot problems and injuries.