Erik Simonsen

Biomechanical responses to repeated stretches in human hamstring muscle in vivo

To examine stiffness, energy, and passive torque in the dynamic and static phases of a stretch maneuver in the human hamstring muscle in vivo we used a test- retest protocol and a repeated stretches protocol. Re sistance to stretch was defined as passive torque (in newton-meters) offered by the hamstring muscle group during passive knee extension as measured using an isokinetic dynamometer with a modified thigh pad. In 13 uninjured subjects, the knee was passively ex tended to a predetermined final position (0.0875 rad/ sec, dynamic phase) where it remained stationary for 90 seconds (static phase). The test-retest protocol in cluded two tests administered 1 hour apart. On a sep arate occasion, five consecutive static stretches were administered separated by 30 seconds and followed by a sixth stretch 1 hour later. For the test-retest phase, stiffness and energy in the dynamic phase and passive torque in the static phase did not differ and yielded correlations of r = 0.91 to 0.99. During the static phase, passive torque declined in both tests (P < 0.0001). For the repeated stretches, decreases were observed for energy (P < 0.01) and stiffness (P < 0.05) in the dynamic phase and for passive torque (P < 0.0001) in the static phase. However, the decline in the variables returned to baseline within 1 hour. The data show that the method employed is a useful tool for measuring biomechanical variables during a stretch maneuver. This may provide a more detailed method to examine skeletal muscle flexibility.

Early detection strategies for untreated first-episode psychosis

Some studies in first-episode schizophrenia correlate shorter duration of untreated psychosis (DUP) with better prognosis, suggesting that timing of treatment may be important. A three-site prospective clinical trial in Norway and Denmark is underway to investigate the effect of the timing of treatment in first-episode psychosis. One health care sector (Rogaland, Norway) is experimental and has developed an early detection (ED) system to reduce DUP. Two other sectors (Ullevål, Norway, and Roskilde, Denmark) are comparison sectors and rely on existing detection and referral systems for first-episode cases. The study ultimately will compare early detected with usual detected patients. This paper describes the studys major independent intervention variable, i.e. a comprehensive education and detection system to change DUP in first onset psychosis. System variables and first results from the four-year inclusion period (1997-2000) are described. It includes targeted information towards the general public, health professionals and schools, and ED teams to recruit appropriate patients into treatment as soon as possible. This plus easy access to psychiatric services via ED teams systematically changed referral patterns of first-episode schizophrenia. DUP was reduced by 1.5 years (mean) from before the time the ED system was instituted (to 0.5 years). The ED strategies appear to be effective and to influence directly the communitys help-seeking behaviour.

Early detection and intervention in first-episode schizophrenia: a critical review

Objective: To review the literature on early intervention in psychosis and to evaluate relevant studies.

Mechanical and physiological responses to stretching with and without preisometric contraction in human skeletal muscle

Abstract Objective: To examine electromyography (EMG) activity, passive torque, and stretch perception during static stretch and contract-relax stretch. Design: Two separate randomized crossover protocols: (1) a constant angle protocol on the right side, and (2) a variable angle protocol on the left side. Subjects: 10 male volunteers. Intervention: Stretch-induced mechanical response in the hamstring muscles during passive knee extension was measured as knee flexion torque (Nm) while hamstring surface EMG was measured. Final position was determined by extending the knee to an angle that provoked a sensation similar to a stretch maneuver. Constant angle stretch: The knee was extended to 10/dg below final position, held 10sec, then extended to the final position and held for 80sec. Variable angle stretch: The knee was extended from the starting position to 10/dg below the final position, held 10sec, then extended to the onset of pain. Subjects produced a 6-sec isometric contraction with the hamstring muscles 10/dg below the final position in the contract-relax stretch, but not in the static stretch. Main Outcome Measures: Passive torque, joint range of motion, velocity, and hamstring EMG were continuously recorded. Results: Constant angle contract-relax and static stretch did not differ in passive torque or EMG response. In the final position, passive torque declined 18% to 21% in both contract-relax and static stretch ( p p Conclusion: At a constant angle the viscoelastic and EMG response was unaffected by the isometric contraction. The variable angle protocol demonstrated that PNF stretching altered stretch perception.

Viscoelastic response to repeated static stretching in the human hamstring muscle

The purpose of this study was (1) to evaluate the reproducibility of a new method of measuring passive resistance to stretch in the human hamstring muscle group, in vivo, using a test re‐test protocol and 2) to examine the effect of repeated stretches. Passive resistance offered by the hamstring muscle group during knee extension was measured in 10 subjects as knee flexion moment (Nm) using a KinCom dynamometer. The knee was passively extended at 5 deg/s to the final position where it remained stationary for 90 s (static phase). EMG of the hamstring muscle was also measured. The test re‐test protocol included 2 tests (tests 1 and 2) administered 1 h apart. On a separate occasion 5 consecutive static stretches were administered (stretches 1–5) separted by 30 s. Stretch 6 was administered one hour after stretch 5. In the static phase passive resistance did not differ between test 1 and test 2. Resistance declined in both tests 1 and 2, whereas EMG activity remained unchanged. The decline in resistance was significant up to 45 s. For the repeated stretches there was an effect of time (90 s) and stretch (1–5) with a significant interaction i.e., resistance diminished with stretches, and the 90‐s decline was less as more stretches were performed. Passive resistance in stretch 6 was lower than in stretch 1. The present study has demonstrated a reliable method for studying resistance to stretch of the human hamstring muscle group. A viscoelastic response of the human hamstring muscle was shown. With 5 repeated stretches, resistance to stretch diminished and each stretch exibited a viscoelastic response, albeit less with each subsequent stretch. The effect of 5 repeated stretches was significant 1 h later.

Biomechanical differences in soccer kicking with the preferred and the non-preferred leg

The aims of this study were to examine the release speed of the ball in maximal instep kicking with the preferred and the non-preferred leg and to relate ball speed to biomechanical differences observed during the kicking action. Seven skilled soccer players performed maximal speed place kicks with the preferred and the nonpreferred leg; their movements were filmed at 400 Hz. The inter-segmental kinematics and kinetics were derived. A coefficient of restitution between the foot and the ball was calculated and rate of force development in the hip flexors and the knee extensors was measured using a Kin-Com dynamometer. Higher ball speeds were achieved with the preferred leg as a result of the higher foot speed and coefficient of restitution at the time of impact compared with the non-preferred leg. These higher foot speeds were caused by a greater amount of work on the shank originating from the angular velocity of the thigh. No differences were found in muscle moments or rate of force development. We conclude that the difference in maximal ball speed between the preferred and the non-preferred leg is caused by a better inter-segmental motion pattern and a transfer of velocity from the foot to the ball when kicking with the preferred leg.

Prevention of Negative Symptom Psychopathologies in First-Episode Schizophrenia: Two-Year Effects of Reducing the Duration of Untreated Psychosis

BACKGROUND The duration of untreated psychosis (DUP)-the time from onset of psychotic symptoms to the start of adequate treatment--is consistently correlated with better course and outcome, but the mechanisms are poorly understood. OBJECTIVE To report the effects of reducing DUP on 2-year course and outcome. DESIGN A total of 281 patients with a DSM-IV diagnosis of nonorganic, nonaffective psychosis coming to their first treatment during 4 consecutive years were recruited, of which 231 participated in the 2-year follow-up. A comprehensive early detection (ED) system, based on public information campaigns and low-threshold-psychosis-detecting teams, was introduced in 1 health care area (ED area), but not in a comparable area (no-ED area). Both areas ran equivalent 2-year treatment programs. RESULTS First-episode patients from the ED area had a significantly lower DUP, better clinical status, and milder negative symptoms at the start of treatment. There were no differences in treatment received for the first 2 years between the groups. The difference in negative symptoms was maintained at the 1-year follow-up. There was a statistically significant difference in the Positive and Negative Syndrome Scale negative component, cognitive component, and depressive component in favor of the ED group at the 2-year follow-up. Multiple linear regression analyses gave no indication that these differences were due to confounders. CONCLUSION Reducing the DUP has effects on the course of symptoms and functioning, including negative symptoms, suggesting secondary prevention of the negative psychopathologies in first-episode schizophrenia.

Long-Term Follow-Up of the TIPS Early Detection in Psychosis Study: Effects on 10-Year Outcome

OBJECTIVE Early detection in first-episode psychosis confers advantages for negative, cognitive, and depressive symptoms after 1, 2, and 5 years, but longitudinal effects are unknown. The authors investigated the differences in symptoms and recovery after 10 years between regional health care sectors with and without a comprehensive program for the early detection of psychosis. METHOD The authors evaluated 281 patients (early detection, N=141) 18 to 65 years old with a first episode of nonaffective psychosis between 1997 and 2001. Of these, 101 patients in the early-detection area and 73 patients in the usual-detection area were followed up at 10 years, and the authors compared their symptoms and recovery. RESULTS A significantly higher percentage of early-detection patients had recovered at the 10-year follow-up relative to usual-detection patients. This held true despite more severely ill patients dropping out of the study in the usual-detection area. Except for higher levels of excitative symptoms in the early-detection area, there were no symptom differences between the groups. Early-detection recovery rates were higher largely because of higher employment rates for patients in this group. CONCLUSIONS Early detection of first-episode psychosis appears to increase the chances of milder deficits and superior functioning. The mechanisms by which this strategy improves the long-term prognosis of psychosis remain speculative. Nevertheless, our findings over 10 years may indicate that a prognostic link exists between the timing of intervention and outcome that deserves additional study.

Amplitude of the human soleus H reflex during walking and running

1 The objective of the study was to investigate the amplitude and modulation of the human soleus Hoffmann (H) reflex during walking and during running at different speeds. 2 EMGs were recorded with surface electrodes from the soleus, the medial and lateral head of the gastrocnemius, the vastus lateralis and the anterior tibial muscles. The EMGs and the soleus H reflex were recorded while walking on a treadmill at 4.5 km h−1 and during running at 8, 12 and 15 km h−1. 3 The amplitudes of the M wave and the H reflex were normalized to the amplitude of a maximal M wave elicited by a supramaximal stimulus just after the H reflex to compensate for movements of the recording and stimulus electrodes relative to the nerve and muscle fibres. The stimulus intensity was set to produce M waves that had an amplitude near to 25% of the maximal M wave measured during the movements. As an alternative, the method of averaging of sweeps in sixteen intervals of the gait cycle was applied to the data. In this case the amplitude of the H reflex was expressed relative to the maximal M wave measured whilst in the standing position. 4 The amplitude of the H reflex was modulated during the gait cycle at all speeds. During the stance phase the reflex was facilitated and during the swing and flight phases it was suppressed. The size of the maximal M wave varied during the gait cycle and this variation was consistent for each subject although different among subjects. 5 The peak amplitude of the H reflex increased significantly (P= 0.04) from walking at 4.5 km h−1 to running at 12 and 15 km h−1 when using the method of correcting for variations of the maximal M wave during the gait cycle. The sweep averaging method showed a small but non‐significant decrease (P= 0.3) from walking to running at 8 km h−1 and a small decrease with running speed (P= 0.3). The amplitude of the EMG increased from walking to running and with running speed. 6 The relatively large H reflex recorded during the stance phase in running indicates that the stretch reflex may influence the muscle mechanics during the stance phase by contributing to the motor output and enhancing muscle stiffness.

The course of neurocognitive functioning in first-episode psychosis and its relation to premorbid adjustment, duration of untreated psychosis, and relapse

The aim was to determine the post-onset longitudinal course of cognitive functioning in first-episode psychoses and to examine how premorbid adjustment, duration of untreated psychosis (DUP), and clinical variables such as relapse are associated with that course. Consecutive patients with a DSM-IV diagnosis of non-organic psychosis coming to their first treatment in the health care areas under study were included. Ultimately, 207 patients were assessed neuropsychologically at baseline, 138 were reassessed one year later, and 111 two years later. Five dimensions were identified through principal component analysis of eight neuropsychological (NP) test results: Working Memory (WM), Executive Function (EF), Verbal Learning (VL), Impulsivity (Im), and Motor Speed (MS). No major changes were found in the level of neurocognitive functioning from baseline to the 1-year and 2-year follow-ups. Patients with good initial levels of premorbid academic functioning had consistently better scores on WM at all three time points. No association was found between DUP and the longitudinal course of neurocognitive function. Significant associations occurred between better WM and VL at 1 and 2 years and fewer relapses during the first year, but not the second. Most NP deficits are in place by onset of psychosis and are stable over two years. Milder WM deficits are associated with higher premorbid academic functioning. More severe deficits in WM and VL are associated with more relapses during the first year. It is unclear whether NP deficits cause relapse, relapse causes NP deficits, or both are manifestations of a third deteriorative process.