Spinal cord injuries – paralysed leg muscles

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HL Gerrits carried out this research under the direction of Professor Anthony J Sargeant (Amsterdam) and Professor Maria Hopman (Nijmegen). It was part of a research collaboration on spinal cord injury between the two Universities (Vrije University Amsterdam, and the Radboud University, Nijmegen – in the Netherlands). Ms Gerrits went on to submit this published research paper as a chapter in her PhD thesis submitted under the supervision of Professor Tony Sargeant in the Vrije University.

 

Reproducibility of contractile properties of the human paralysed and non-paralysed quadriceps muscle

Gerrits HL, Maria T Hopman, Anthony J Sargeant, Arnold de Haan.

Clinical Physiology

Clin Physiol. 2001 Jan;21(1):105-13

Abstract
This study assessed the reproducibility of electrically evoked, isometric quadriceps contractile properties in eight people with spinal cord injury (SCI) and eight able-bodied (AB) individuals. Over all, the pooled coefficients of variation (CVps) in the SCI group were significantly lower (ranging from 0.03 to 0.15) than in the AB group (ranging from 0.08 to 0.21) (P<0.05). Furthermore, in all subjects, the variability of force production increased as stimulation frequency decreased (P<0.01). In subjects with SCI, variables of contractile speed are clearly less reproducible than tetanic tension or resistance to fatigue. Contractile properties of quadriceps muscles of SCI subjects were significantly different from that of AB subjects. Muscles of people with SCI were less fatigue resistant (P<0.05) and produced force-frequency relationships that were shifted to the left, compared with AB controls (P<.01). In addition, fusion of force responses resulting from 10 Hz stimulation was reduced (P<.05) and speed of contraction (but not relaxation) was increased (P<0.05), indicating an increased contractile speed in paralysed muscles compared with non-paralysed muscles. These results correspond with an expected predominance of fast glycolytic muscle fibres in paralysed muscles. It is concluded that quadriceps dynamometry is a useful technique to study muscle function in non-paralysed as well as in paralysed muscles. Furthermore, these techniques can be reliably used, for example, to assess therapeutic interventions on paralysed muscles provided that expected differences in relative tetanic tension and fatigue resistance are larger than approximately 5% and differences in contractile speed are larger than approximately 15%
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Human Achilles Tendon – in-vivo estimates of the moment arm

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This research publication by (now Professor) Costis Maganaris as first author was an important technical analysis which formed part of his PhD thesis which was jointly supervised by Professor Vasilios Baltzopoulos and Professor Anthony J Sargeant

In vivo measurement-based estimations of the human Achilles tendon moment arm

Costis N Maganaris, Vasilios Baltzopoulos, Anthony J Sargeant.

European Journal of Applied Physiology

Eur J Appl Physiol. 2000 Nov;83(4 -5):363-9

Abstract
The aim of the present study was to estimate and compare in vivo measurement-based Achilles tendon moment arm lengths at rest and during isometric plantarflexion maximum voluntary contraction (MVC) using the centre-of-rotation (COR) and the tendon-excursion (TE) methods. Both methods were based on morphometric analysis of sagittal-plane magnetic resonance images of the foot. Using the COR method, moment arms were obtained at ankle angles from 15 degrees of dorsiflexion to 30 degrees of plantarflexion in steps of 15 degrees, digitizing the perpendicular distance from a moving centre of rotation in the tibio-talar joint to the Achilles tendon action line. The TE method was based on measurement of calcaneal displacement along the tibial axis during 15 degrees rotations of the ankle joint, from 30 degrees of dorsiflexion to 45 degrees of plantarflexion. The two methods gave similar estimations at rest varying from 4.3 to 5.6 cm. Using the COR method, the Achilles tendon moment arm during MVC was larger by 1-1.5 cm (22-27%, P < 0.01) than the respective resting value. In contrast, no difference (P > 0.05) was found between the resting and MVC moment arm estimations of the TE method. The disagreement in moment arms during MVC may be attributed to differences in the assumptions made between the two methods. The TE method has more limitations than the COR method and its estimations during MVC should be treated with caution. Resting Achilles tendon moment arm estimations of the COR method should be multiplied by 1.22-1.27 when maximal isometric plantarflexion joint moments, musculotendon forces and stresses are predicted using modelling

Functional Electrical Stimulation of leg muscles in people with spinal cord injury

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This research publication in the medical journal ‘Spinal Cord’ formed part of a research programme carried out by HL Gerrits under the direction and supervision of Professor Maria Hopman of Radboud University of Nijmegen, Professor Anthony J Sargeant and Arnold de Haan of the Vrije University of Amsterdam. The publication formed a chapter in the PhD thesis of Ms Gerrits.

Altered contractile properties of the quadriceps muscle in people with spinal cord injury following functional electrical stimulated cycle training

Gerrits HL, Arnold de Haan, Anthony J Sargeant, Dallmeijer A, Maria T Hopman.

Spinal Cord. 2000 Apr;38(4):214-223

Abstract
STUDY DESIGN: A longitudinal training study.
OBJECTIVES: To assess if contractile speed and fatigability of paralysed quadriceps muscles in individuals with spinal cord injury (SCI) can be altered by functional electrical stimulation leg cycle ergometry (FES-LCE) training.
SETTINGS: The Sint Maartenskliniek rehabilitation centre and the University of Nijmegen, Nijmegen, the Netherlands.
METHODS: Contractile properties of the quadriceps muscle were studied in seven people with motor-complete SCI who participated in a FES-LCE training program. Subjects trained for 30 min, three times per week for 6 weeks. Contractile speed and fatigue characteristics of electrically stimulated isometric contractions were compared before and after 6 weeks of FES-LCE.
RESULTS: Fatigue resistance improved following FES-LCE training as indicated by the higher forces maintained in response to repetitive electrical stimulation. In contrast with an improved fatigue resistance, the maximal rate of force rise was unaffected, the speed of relaxation increased and the fusion of a 10 Hz force signal decreased. Furthermore, the force-frequency relationship shifted to the right at low stimulation frequencies, indicated by a decline in the ratio of 1 and 100 Hz force responses as well as the ratio of 10 and 100 Hz force responses.
CONCLUSION: FES-LCE training can change the physiological properties of the quadriceps muscle in people with SCI. Even after a short period of training, the stimulated muscles become more resistant to fatigue. Furthermore, the increased speed of relaxation and associated decreased fusion and altered force-frequency relationship following training may be related to adaptations in the calcium handling processes, which reflect an early response of long-term disused muscles.

The electrical stimulation of leg muscles (including FES) of people with Spinal cord injury will be affected by the temperature of the muscle

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This research publication formed part of the PhD thesis of H.L. Gerrits who was directed by a team of colleagues from the Vrije Universiteit of Amsterdam headed by Professor Anthony J Sargeant and Professor Maria Hopman from the Radboud University Nijmegen. The paper shows that (the typically) low muscle temperatures in the limbs of people with spinal cord injury will change the the contractile properties of the muscles when functional electrical stimulation is applied or the muscle properties are assessed in the laboratory.

Influence of muscle temperature on the contractile properties of the quadriceps muscle in humans with spinal cord injury

H. L. GERRITS, ARNOLD DE HAAN, MARIA T HOPMAN, LUC H. V. VAN DER WOUDE, ANTHONY J SARGEANT.

Clinical Science
Clin Sci (Lond). 2000 Jan;98(1):31-8
Abstract
Low muscle temperature in paralysed muscles of individuals with spinal cord injury may affect the contractile properties of these muscles. The present study was therefore undertaken to assess the effects of increased muscle temperature on the isometric contractile properties of electrically stimulated paralysed quadriceps muscles. When muscle temperature at a depth of 3 cm was increased from approximately 32 degrees C to approximately 36 degrees C by ultra-short-wave application, the half-relaxation time shortened and low-frequency force responses became less fused, but the maximal rate of increase in force remained unchanged. Heating had no effect upon either force decline or slowing of relaxation during fatiguing contractions. The force-frequency relationship of the paralysed quadriceps muscle was shifted to the right after the muscle was heated. Despite this shift, however, the relationship still resembled that in muscles of non-paralysed individuals, probably due to the unexplained high twitch forces. These results indicate that reduced muscle temperature in spinal-cord-injured individuals may lead to an underestimation of the changes in contractile properties in terms of relaxation rate or the degree of fusion with low-frequency stimulation. In addition, the force-frequency relationship of paralysed muscles does not accurately reflect the magnitude of these changes, even when the muscle is heated, and should therefore be treated with caution.

Prior activation can change the maximum power generated by skeletal muscle

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Fabio Abbate was a PhD student working under the direction of Professor Anthony J Sargeant in Amsterdam. This was one of a number of research papers published in eminent scientific journals which formed part of Fabio Abbate’s PhD thesis successfully submitted at the Vrije Universiteit of Amsterdam.

Effects of high-frequency initial pulses and posttetanic potentiation on power output of skeletal muscle

F. Abbate, Anthony J Sargeant, P. W. L. Verdijk, Arnold de Haan

Journal of Applied Physiology
J Appl Physiol. 2000 Jan;88(1):35-40.
Abstract
The effects of high-frequency initial pulses (HFIP) and posttetanic potentiation on mechanical power output during concentric contractions were examined in the in situ medial gastrocnemius of the rat with an intact origin on the femur and blood supply. Stimulation of the muscle was performed via the severed sciatic nerve. In the experiments, HFIP or the potentiating tetanus was followed by a stimulation of 80, 120, or 200 Hz. The results showed that both HFIP and the tetanus increased power output at high contraction velocities (>75 mm/s) when followed by a train of 80 or 120 Hz (200 Hz resulted in no effects). Mechanical power output was increased maximally by HFIP to 120 and 168% by the tetanus. Furthermore, when HFIP or the tetanus were followed by a train of 80 Hz, the peak power in the power-velocity curve tended to be shifted to a higher velocity.

Optimum pedalling rates in cycling

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The data for this research publication was collected in Amsterdam by Jerzy Zoladz and Arno Rademaker working under the supervision of Professor Anthony J Sargeant. The concept of optimum movement frequencies in human locomotion had been a long standing interest of Tony Sargeant’s and the results from this study build on earlier studies. It is concluded that choosing a high pedalling rate (around 100 revs/min) when performing high intensity cycling exercise may be beneficial since it provides greater reserve in power generating capability and this may be advantageous to the muscle in terms of resisting fatigue.

Human muscle power generating capability during cycling at different pedalling rates

Jerzy A Zoladz, Arno C H J Rademaker, and Anthony J Sargeant

Experimental Physiology

Exp Physiol. 2000 Jan;85(1):117-24

Abstract
The effect of different pedalling rates (40, 60, 80, 100 and 120 rev min-1) on power generating capability, oxygen uptake (O2) and blood lactate concentration [La]b during incremental tests was studied in seven subjects. No significant differences in O2,max were found (mean +/- S.D., 5.31 +/- 0.13 l min-1). The final external power output delivered to the ergometer during incremental tests (PI,max) was not significantly different when cycling at 60, 80 or 100 rev min-1 (366 +/- 5 W). A significant decrease in PI,max of 60 W was observed at 40 and 120 rev min-1 compared with 60 and 100 rev min-1, respectively (P < 0.01). At 120 rev min-1 there was also a pronounced upward shift of the O2-power output (O2-P) relationship. At 50 W O2 between 80 and 100 rev min-1 amounted to +0.43 l min-1 but to +0.87 l min-1 between 100 and 120 rev min-1. The power output corresponding to 2 and 4 mmol l-1 blood lactate concentration (P[La]2 and P[La]4 ) was also significantly lower (> 50 W) at 120 rev min-1 (P < 0.01) while pedalling at 40, 60, 80 and 100 rev min-1 showed no significant difference. The maximal peak power output (PM, max) during 10 s sprints increased with pedalling rate up to 100 rev min-1. Our study indicates that with increasing pedalling rate the reserves in power generating capability increase, as illustrated by the PI,max/PM,max ratio (54.8, 44.8, 38.1, 34.6, 29.2%), the P[La]4/PM,max ratio (50.4, 38.9, 31.0, 27.7, 22.9%) and the P[La]2/PM,max ratio (42.8, 33.5, 25.6, 23.1, 15.6%) increases.
Taking into consideration the O2,max, the PI,max and the reserve in power generating capability we concluded that choosing a high pedalling rate when performing high intensity cycling exercise may be beneficial since it provides greater reserve in power generating capability and this may be advantageous to the muscle in terms of resisting fatigue. However, beyond 100 rev min-1 there is a decrease in external power that can be delivered for an given O2 with an associated earlier onset of metabolic acidosis and clearly this will be disadvantageous for sustained high intensity exercise.

Effect of Muscle Temperature on Human Muscle Function

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This research was initiated by Professor Anthony Sargeant and Professor David Jones and carried out in Amsterdam.

Temperature effect on the rates of isometric force development and relaxation in the fresh and fatigued human adductor pollicis muscle

de Ruiter CJ, David A Jones, Anthony J Sargeant, Arnold de Haan.

Experimental Physiology

Exp Physiol. 1999 Nov;84(6):1137-50

Abstract
The purpose of the present study was to investigate the effect of temperature on the rates of isometric force development and relaxation in electrically activated fresh and fatigued human adductor pollicis muscle. Following immersion of the lower arm for 20 min in water baths of four different temperatures, muscle temperatures were approximately 37, 31, 25 and 22 C. Maximal isometric force was reduced by 16.8 +/- 1.5 % at 22 C. The stimulation frequency-force and -rate of force development relationships were shifted to the left at lower temperatures. Q10 values for the maximal rates of force development and relaxation, and the times for 100 to 50 % and 50 to 25 % force relaxation, were about 2.0 between 37 and 25 C and about 3.8 between 25 and 22 C. However, the time for 50 to 25 % force relaxation had a relatively high Q10 value between 25 and 22 C (6.9) and this parameter also appeared to be more sensitive to fatigue compared to the other indices of relaxation. Nevertheless, the effect of fatigue on all parameters decreased with cooling over the entire (37-22 C) temperature range