Ann-Katrin Stensdotter

Quadriceps Activation in Closed and in Open Kinetic Chain Exercise

PURPOSE For treatment of various knee disorders, muscles are trained in open or closed kinetic chain tasks. Coordination between the heads of the quadriceps muscle is important for stability and optimal joint loading for both the tibiofemoral and the patellofemoral joint. The aim of this study was to examine whether the quadriceps femoris muscles are activated differently in open versus closed kinetic chain tasks. METHODS Ten healthy men and women (mean age 28.5 +/- 0.7) extended the knees isometrically in open and closed kinetic chain tasks in a reaction time paradigm using moderate force. Surface electromyography (EMG) recordings were made from four different parts of the quadriceps muscle. The onset and amplitude of EMG and force data were measured. RESULTS In closed chain knee extension, the onset of EMG activity of the four different muscle portions of the quadriceps was more simultaneous than in the open chain. In open chain, rectus femoris (RF) had the earliest EMG onset while vastus medialis obliquus was activated last (7 +/- 13 ms after RF EMG onset) and with smaller amplitude (40 +/- 30% of maximal voluntary contraction (MVC)) than in closed chain (46 +/- 43% MVC). CONCLUSIONS Exercise in closed kinetic chain promotes more balanced initial quadriceps activation than does exercise in open kinetic chain. This may be of importance in designing training programs aimed toward control of the patellofemoral joint.

The relationship between motor competence, physical fitness and self-perception in children.

AIM The aim of the current research was to explore the relationship between motor competence, physical fitness and self-perception, and to study to which extent this relationship may vary by gender. METHODS A sample of 67 children (mean age 11.46 years, SD 0.27) completed Harters Self-Perception Profile for Children (SPPC), the Movement Assessment Battery for Children (MABC) and the Test of Physical Fitness (TPF) to assess self-perception, motor competence and physical fitness. RESULTS The SPPC was stronger related to total score on TPF than to total score on MABC. However, when looking at boys and girls separately, this result was found for the boys only. In the group in general, total scores on both TPF and MABC correlated significantly with three of the domains of SPPC (social acceptance, athletic competence and physical appearance) and general self-worth. This relationship varied by gender. Interestingly, TPF was highest correlated with perception of athletic competence in boys but with perception of social acceptance in girls. A high and significant correlation was found between physical fitness and motor competence for both genders. CONCLUSION The results indicated a strong relationship between physical fitness, motor competence and self-perception in children that varied by gender. This implies that all these factors are essential contributions in order to facilitate participation in physical activity in children.

Kinematic analyses during stair descent in young women with patellofemoral pain

BACKGROUND Compensatory movement strategies may develop in response to pain to avoid stress on the affected area. Patellofemoral pain is characterised by intermittent periods of pain and the present study addresses whether long-term pain leads to compensatory movement strategies that remain even when the pain is absent. METHOD Lower extremity kinematics in three dimensions was studied in stair descent in 17 women with patellofemoral and in 17 matched controls. A two-dimensional geometric model was constructed to normalise kinematic data for subjects with varying anthropometrics when negotiating stairs of fixed proportions. RESULTS There were minor differences in movement patterns between groups. Knee joint angular velocity in the stance leg at foot contact was lower and the movement trajectory tended to be jerkier in the patellofemoral group. The two-dimensional model showed greater plantar flexion in the swing leg in preparation for foot placement in the patellofemoral group. INTERPRETATION The results indicate that an altered stair descent strategy in the patellofemoral group may remain also in the absence of pain. The biomechanical interpretation presumes that the strategy is aimed to reduce knee joint loading by less knee joint moment and lower impact force.

Changes in the spatio‐temporal organization of the trapezius muscle activity in response to eccentric contractions

We hypothesized changes in the spatial organization of the trapezius muscle electromyographic (EMG) activity after a shoulder eccentric exercise. The rate of perceived exertion (RPE), the size of the soreness area, maximum force and, EMG from the upper, middle and lower trapezius were recorded. Root mean square (RMS), mean frequency (MNF) and normalized mutual information (a measure of functional connectivity between muscle sub‐divisions) were computed during submaximal dynamic and static contractions performed before, immediately after and 24 h after exercise. Immediately after exercise, RPE, soreness area, RMS from the upper and middle trapezius and normalized mutual information among upper–middle sub‐divisions increased while MNF decreased for the middle trapezius (P<0.05). After 24 h, the maximum force decreased. RMS from the upper trapezius and normalized mutual information among upper–middle trapezius sub‐divisions were higher than before exercise. MNF values increased from immediately after to 24 h after for the upper and lower trapezius (P<0.05). The current results underlined changes in the spatio‐temporal organization of the trapezius in response to shoulder eccentric exercise. The observed changes in EMG temporal and spectral contents and the enhanced sub‐division coupling underlined the functional role of spatial variations of the EMG activity during muscle fatigue and in the presence of delayed‐onset muscle soreness.

The Second Physical Therapy Summit on Global Health: developing an action plan to promote health in daily practice and reduce the burden of non-communicable diseases

Abstract Based on indicators that emerged from The First Physical Therapy Summit on Global Health (2007), the Second Summit (2011) identified themes to inform a global physical therapy action plan to integrate health promotion into practice across the World Confederation for Physical Therapy (WCPT) regions. Working questions were: (1) how well is health promotion implemented within physical therapy practice; and (2) how might this be improved across five target audiences (i.e. physical therapist practitioners, educators, researchers, professional body representatives, and government liaisons/consultants). In structured facilitated sessions, Summit representatives (n = 32) discussed: (1) within WCPT regions, what is working and the challenges; and (2) across WCPT regions, what are potential directions using World CaféTM methodology. Commonalities outweighed differences with respect to strategies to advance health-focused physical therapy as a clinical competency across regions and within target audiences. Participants agreed that health-focused practice is a professional priority, and a strategic action plan was needed to develop it as a clinical competency. The action plan and recommendations largely paralleled the principles and objectives of the World Health Organization’s non-communicable diseases action plan. A third Summit planned for 2015 will provide a mechanism for follow-up to evaluate progress in integrating health-focused physical therapy within the profession.

Anterior cruciate ligament injury after more than 20 years. II. Concentric and eccentric knee muscle strength.

The long‐term consequences on knee muscle strength some decades after rupture of the anterior cruciate ligament (ACL) are not established. The aims of our study were to examine peak torque more than 20 years after ACL injury and to compare their knee muscle strength to that of healthy controls. We tested 70 individuals with unilateral ACL injury 23 ± 2 years after injury, whereof 33 (21 men) were treated with physiotherapy in combination with ACL reconstruction (ACLR) and 37 (23 men) with physiotherapy alone (ACLPT). These were compared with 33 age‐ and gender‐matched controls (21 men). A Kin‐Com® dynamometer (90°/s) was used to measure peak torque in knee flexion and extension in both concentric and eccentric contractions. Knee extension peak torque, concentric and eccentric, was ∼10% lower for the injured leg compared with the non‐injured leg for both ACLR (P < 0.001; P < 0.001) and ACLPT (P = 0.007; P = 0.002). The ACLPT group also showed reduced eccentric knee flexion torque of the injured leg (P = 0.008). The strength of the non‐injured leg in both ACL groups was equal to that of controls. No difference was seen for those with no‐or‐low degree of knee osteoarthritis compared to those with moderate‐to‐high degree of osteoarthritis. ACL injury may lead to a persistent reduction of peak torque in the injured leg, which needs to be considered across the lifespan.

Quadriceps EMG in Open and Closed Kinetic Chain Tasks in Women With Patellofemoral Pain

The authors investigated whether the discrepancy noted in the literature regarding delayed and decreased activity in vastus medialis obliquus (VMO) in people with patellofemoral pain (PFP) depends on the nature of the open kinetic chain (OKC) and the closed kinetic chain (CKC) in the experimental task. They hypothesized that activity in VMO would be more delayed and decreased in CKC tasks than in OKC tasks. Women with PFP (n = 17) and healthy controls (n = 17) performed isometric quadriceps contractions in CKC and OKC tasks. The authors manipulated only the application of resistance. Electromyographs (EMGs) showed that participants with PFP reacted later and activated the quadriceps more in the CKC task but had intramuscular quadriceps coordination similar to that of controls. The nature of the OKC task or the CKC task does not seem to explain contradictory findings regarding VMO activation.

Anterior cruciate ligament injury about 20 years post-treatment : a kinematic analysis of one-leg hop

Reduced dynamic knee stability, often evaluated with one‐leg hops (OLHs), is reported after anterior cruciate ligament (ACL) injury. This may lead to long‐standing altered movement patterns, which are less investigated. 3D kinematics during OLH were explored in 70 persons 23 ± 2 years after ACL injury; 33 were treated with physiotherapy in combination with ACL reconstruction (ACLR) and 37 with physiotherapy alone (ACLPT). Comparisons were made to 33 matched controls. We analyzed (a) maximal knee joint angles and range of motion (flexion, abduction, rotation); (b) medio‐lateral position of the center of mass (COM) in relation to knee and ankle joint centers, during take‐off and landing phases. Unlike controls, ACL‐injured displayed leg asymmetries: less knee flexion and less internal rotation at take‐off and landing and more lateral COM related to knee and ankle joint of the injured leg at landing. Compared to controls, ACLR had larger external rotation of the injured leg at landing. ACLPT showed less knee flexion and larger external rotation at take‐off and landing, and larger knee abduction at Landing. COM was more medial in relation to the knee at take‐off and less laterally placed relative to the ankle at landing. ACL injury results in long‐term kinematic alterations during OLH, which are less evident for ACLR.

Compensatory strategies for muscle weakness during stair ascent in subjects with total knee arthroplasty

Subjects with total knee arthroplasty (TKA) exhibit decreased quadriceps and hamstring strength. This may bring about greater relative effort or compensatory strategies to reduce knee joint moments in daily activities. To study gait and map out the resource capacity, knee muscle strength was assessed by maximal voluntary concentric contractions, and whole body kinematics and root mean square (RMS) electromyography (EMG) of vastus lateralis and semitendinosus were recorded during stair ascent in 23 unilateral TKA-subjects ~19 months post-operation, and in 23 healthy controls. Muscle strength and gait velocity were lower in the TKA group, but no significant group differences were found in RMS EMG or forward trunk lean. The results suggest that reduced walking velocity sufficiently compensated for reduced knee muscle strength.

Postural control in quiet standing in patients with psychotic disorders

There is evidence that patients with psychotic conditions display greater center of pressure (CoP) displacement during quite standing than healthy subjects, but the underlying impairments in the control mechanisms are uncertain. The aim of this study was to identify the nature of possible impairments in the control of posture by modulation of visual and kinesthetic information during quiet standing. Center of pressure (CoP) data and whole-body kinematics of the center of mass (CoM) were recorded during quite standing on a firm surface with eyes open and with eyes closed, and standing with eyes open on a yielding surface. During all three conditions, patients displayed greater migration of CoM and CoP-CoM, a measure related to ankle joint torque, whereas CoP-frequency (MPF) was similar in patients and healthy subjects. Our results suggested that greater postural sway in patients may depend on disproportionally large ankle joint torque without corresponding increase in frequency. Furthermore, interactions between groups and conditions suggested that the patients made less use of visual information for postural control than the healthy subjects.