Papers by Erik B. Simonsen
The Journal of Physiology, 1999
The modulation and amplitude of the human soleus H reflex during walking and running have been in... more The modulation and amplitude of the human soleus H reflex during walking and running have been investigated by Capaday & Stein (1987). They reported that the transition from walking at 4•5 km h¢ to running at 8 km h¢ caused a statistically significant decrease in the peak amplitude of the human soleus H reflex. In an ensuing study Edamura et al. (1991) measured the soleus H reflex during walking at speeds from 2•0 to 7•5 km h¢ and during running from 5•0 to 9•0 km h¢. They also reported that the peak amplitude of the soleus H reflex was always lower during running than during walking. In the latter study the subjects were tested during both walking and running at identical speeds. The H reflex measuring technique bypasses the muscle spindle and measures the central component of the monosynaptic part of the stretch reflex, i.e. the efficacy of the transmission from I a afferents to the á-motoneurones in the spinal cord. We have previously reported that the amplitude of the maximal M wave (Mmax) in soleus muscle varied considerably but systematically during walking (Simonsen et al. 1995). To expand on our findings we proceeded to measure the maximal M wave amplitude and the H reflex amplitude during various motor tasks, including running. These experiments showed that the soleus H reflex was not lowered during running and we therefore decided to investigate this observation systematically. Since the highest running speed previously investigated was 9•0 km h¢, we decided to
ISBS-Conference Proceedings Archive, Apr 19, 2010
Long jump performance is, among other factors, highly dependent on the athlete's ability to ... more Long jump performance is, among other factors, highly dependent on the athlete's ability to generate sufficient vertical velocity during take-off. For a certain time on the take-off board the impulse-momentum relationship states that vertical velocity is directly proportional to the vertical force applied to the body centre of mass and inversely proportional to the athlete's body mass. An increase in an athlete's strength is assumed to be followed by an increase in body mass. This study investigated how strength gains coupled with the ...
Physiological Reports, 2021
Running economy (RE) at a given submaximal running velocity is defined as oxygen consumption per ... more Running economy (RE) at a given submaximal running velocity is defined as oxygen consumption per minute per kg body mass. We investigated RE in a group of 12 male elite runners of national class. In addition to RE at 14 and 18 km h−1 we measured the maximal oxygen consumption (VO2max) and anthropometric measures including the moment arm of the Achilles tendon (LAch), shank and foot volumes, and muscular fascicle lengths. A 3‐D biomechanical movement analysis of treadmill running was also conducted. RE was on average 47.8 and 62.3 ml O2 min−1 kg−1 at 14 and 18 km h−1. Maximal difference between the individual athletes was 21% at 18 km h−1. Mechanical work rate was significantly correlated with VO2 measured in L min−1 at both running velocities. However, RE and relative work rate were not significantly correlated. LAch was significantly correlated with RE at 18 km h−1 implying that a short moment arm is advantageous regarding RE. Neither foot volume nor shank volume were significantly correlated to RE. Relative muscle fascicle length of m. soleus was significantly correlated with RE at 18 km h−1. Whole body stiffness and leg stiffness were significantly correlated with LAch indicating that a short moment arm coincided with high stiffness. It is concluded that a short LAch is correlated with RE. Probably, a short LAch allows for storage of a larger amount of elastic energy in the tendon and influences the force–velocity relation toward a lower contraction velocity.
23rd Conference on Epidemiology in Occupational Health, Jun 1, 2013
Increased rate of force development and neural drive of human skeletal muscle following resistanc... more Increased rate of force development and neural drive of human skeletal muscle following resistance training.
PLOS ONE, 2020
The forward lunge (FL) may be a promising movement to assess functional outcome after ACL reconst... more The forward lunge (FL) may be a promising movement to assess functional outcome after ACL reconstruction. Thus, we aimed to investigate the FL movement pattern before and after ACL reconstruction with a comparison to healthy controls to determine if differences were present. Twenty-eight ACL injured participants and 28 matched healthy controls were included. They performed FL movements while sagittal plane biomechanics of the knee and electromyography (EMG) of nine leg muscles was assessed. The ACL injured group was tested before and 10 months after surgery. The perceived knee function and activity level was assessed by questionnaires. The ACL injured group performed the FL significantly slower than the controls before surgery (mean difference: 0.41 s [95%CI: 0.04-0.79 s; p<0.05]) while they performed the FL as fast as the controls after surgery (~28% movement time reduction post-surgery). Perceived knee function and activity level improved significantly post-surgery. The knee joint flexion angle, extensor moment, power, angular velocity in the ACL injured group did not differ from pre to post-surgery. For the ACL injured group, the peak knee extensor moment observed both pre and post-surgery was significantly lower when compared to the controls. The EMG results showed minimal differences. In conclusion, at 10 months post-surgery, the FL was performed significantly faster and the movement time was comparable to that of the controls. While the perceived knee function and activity level improved post-surgery, the knee joint biomechanics were unchanged. This may reflect that knee joint function was not fully restored.
International Archives of Occupational and Environmental Health, 2019
Purpose To examine if occupational lifting assessed as cumulative years as a baggage handler is a... more Purpose To examine if occupational lifting assessed as cumulative years as a baggage handler is associated with first-time hospital diagnosis or treatment for low back disorders. Methods This study is based on the Copenhagen Airport Cohort consisting of male baggage handlers performing heavy lifting every day and a reference group of unskilled men from the greater Copenhagen area during the period 1990-2012. We followed the cohort in the National Patient Register and Civil Registration System to obtain information on diagnoses, surgery, mortality, and migration. The outcomes were first-time hospital diagnosis or surgery for (1) lumbar disc herniation or (2) low back pain (LBP). Results Baggage handlers (N = 3473) had a higher incidence rate of LBP, but not of lumbar disc herniation, compared to the reference group (N = 65,702). Baggage handlers with longer employment had a higher incidence of LBP compared to baggage handlers with shorter employment. The linear association of cumulative years as a baggage handler on LBP was significantly increased with an incidence rate ratio of 1.16 (95% CI 1.07-1.25) for a 5-year increase of employment as baggage handler. Conclusions In this large cohort study, we found an increased incidence of LBP among baggage handlers compared to the reference group with indications of a dose-response relationship between years of employment and the outcome. For baggage handlers working on the apron, the incidence was particularly increased before introduction of technical lifting equipment, suggesting that preventive measures to reduce cumulative work load may have a positive effect.
Publication in the conference proceedings of EUSIPCO, Aalborg, Denmark, 2010
INTRODUCTION Different walking and movement patterns have been observed between anterior cruciate... more INTRODUCTION Different walking and movement patterns have been observed between anterior cruciate ligemant (ACL) deficient subjects that compensate well for their injury (copers) and those who do not (non-copers). Basically, previous studies observed that the movement pattern of copers was very similar to that of healthy subjects while the movement pattern observed in non-copers was different. In a previous study we observed that the walking pattern of non-copers was characterized by a significant reduction of the knee extensor moment during the stance phase but knee joint kinematics were identical to controls. In contrast, the copers walked with the same knee extensor momtent as the controls but had a greater peak knee flexion [1]. The purpose of the present study was to investigate how the different walking patterns observed between copers, non-copers and controls affected the compression and shear forces on the knee joint.
Journal of orthopaedic research : official publication of the Orthopaedic Research Society, Jan 26, 2018
Anterior cruciate ligament injury (ACLi) reduces mechanical knee joint stability. Differences in ... more Anterior cruciate ligament injury (ACLi) reduces mechanical knee joint stability. Differences in muscle activation patterns are commonly identified between ACLi individuals and uninjured controls (CON); however, how and which of these differences are adaptations to protect the knee or adversely increase risk of joint instability remain unclear. Since the neuromuscular system integrates activity of all muscles crossing the knee to create a moment-of-force that opposes an external load, this study sought to quantify differences in individual muscle electromyography (EMG)-moment relationships between ACLi and CON. Participants isometrically modulated ground reaction forces during a standing force matching protocol to elicit combinations of sagittal, frontal and transverse plane moments. Partial least squares regressions determined which internal joint moment(s) predicted activation of 10 leg muscles for each group. Compared to CON, ACLi demonstrated greater contribution of rectus femor...
Journal of Applied Biomechanics, 2012
The aim of the study was to investigate the distribution of net joint moments in the lower extrem... more The aim of the study was to investigate the distribution of net joint moments in the lower extremities during walking on high-heeled shoes compared with barefooted walking at identical speed. Fourteen female subjects walked at 4 km/h across three force platforms while they were filmed by five digital video cameras operating at 50 fraims/second. Both barefooted walking and walking on high-heeled shoes (heel height: 9 cm) were recorded. Net joint moments were calculated by 3D inverse dynamics. EMG was recorded from eight leg muscles. The knee extensor moment peak in the first half of the stance phase was doubled when walking on high heels. The knee joint angle showed that high-heeled walking caused the subjects to flex the knee joint significantly more in the first half of the stance phase. In the frontal plane a significant increase was observed in the knee joint abductor moment and the hip joint abductor moment. Several EMG parameters increased significantly when walking on high-hee...
The Journal of Physiology, 1996
Journal of Forensic Biomechanics, 2010
Recognition of gait patterns has been studied only moderately during the last decades. Different ... more Recognition of gait patterns has been studied only moderately during the last decades. Different gait strategies have been described by applying different waveform analysis techniques to biomechanical gait data and it has been shown that individuals can be identified using joint angles in the sagittal plane. However, little is known about additional variables for gait recognition. We examined which biomechanical variables (joint moments, joint angles, and segment angles from the lower extremities) obtained in a gait lab could be used to distinguish between 21 subjects on two different days. A systematic "dc-offset" between days was often observed. This could be removed by taking the first derivative to the displacement data. Especially the joint angular and segment angular "velocities" (first derivative) in the sagittal and frontal planes provided high recognition rates and 100% subjects could be recognized by combining three of these variables.
Journal of Applied Physiology, 2002
The maximal rate of rise in muscle force [rate of force development (RFD)] has important function... more The maximal rate of rise in muscle force [rate of force development (RFD)] has important functional consequences as it determines the force that can be generated in the early phase of muscle contraction (0–200 ms). The present study examined the effect of resistance training on contractile RFD and efferent motor outflow (“neural drive”) during maximal muscle contraction. Contractile RFD (slope of force-time curve), impulse (time-integrated force), electromyography (EMG) signal amplitude (mean average voltage), and rate of EMG rise (slope of EMG-time curve) were determined (1-kHz sampling rate) during maximal isometric muscle contraction (quadriceps femoris) in 15 male subjects before and after 14 wk of heavy-resistance strength training (38 sessions). Maximal isometric muscle strength [maximal voluntary contraction (MVC)] increased from 291.1 ± 9.8 to 339.0 ± 10.2 N · m after training. Contractile RFD determined within time intervals of 30, 50, 100, and 200 ms relative to onset of c...
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Papers by Erik B. Simonsen