I ORAL PRESENTATIONS

Topic 3: Exercise Physiology
Chair: Volker Dietz, Michael Potulski

Introduction Lecture:
EXPLOITION OF NEURONAL PLASTICITY AFTER SCI BY EXERCISE

Volker Dietz
Spinal Cord Injury Center, Balgrist University Hospital, 8008 Zurich, Switzerland

After a spinal cord injury (SCI) of the cat or rat, neuronal centers below the level of
lesion exhibit plasticity than can be exploited by specific training paradigms. In individuals
with complete or incomplete SCI, human spinal locomotor centers can be activated
and modulated by locomotor training (facilitating stepping movements of the
legs using body weight support on a treadmill to provide appropriate sensory cues) (for
review see Dietz 2002,2003). Individuals with incomplete SCI benefit from loco-motor
training such that they improve their ability to walk over ground. Load- or hip jointrelated
afferent input seems to be of crucial importance for both the generation of a
locomotor pattern and the effectiveness of the training (Dietz et al. 2002). However, it
may be a critical combination of afferent signals that is needed to generate a locomotor
pattern after severe SCI. Mobility of individuals after a SCI can be im-proved by taking
advantage of the plasticity of the central nervous system and can be maintained with
persistent locomotor activity. In the future, if regeneration ap-proaches can successfully
be applied in human SCI, even individuals with complete SCI may recover waking
ability with locomotor training (Curt et al. 2004).

56/3 Blood lactate disappearance in paraplegic and able-bodied subjects
after exhaustive arm exercise

Leicht C, Perret C
Institute for Clinical Research, Swiss Paraplegic Centre, CH-6207 Nottwil, Switzerland

Objective: Resting skeletal muscles are capable of taking up large amounts of lactate
produced during strenuous exercise. Some of this lactate is oxidised in resting type-Imuscle
fibres. Spinal cord injury (SCI) leads to a loss of trunk and leg muscle tissue
and to a fibre type transition. Six years after an accident leading to complete SCI, no
more type-I-fibres can be found in the legs of paraplegic subjects (P) while the
proportion of these fibres in able-bodied subjects (AB) is up to 40%. Thus, there seems
to be a smaller potential of lactate elimination in the legs of P compared to AB. The aim
of this study was to investigate whether these adaptations in P would impair their ability
to eliminate lactate after exhaustive exercise compared to AB.

Methods: A maximal arm cranking step-test to volitional exhaustion was performed by
8 P and 8 AB. Immediately after the step-test, subjects performed arm cranking for
another 30min at a moderate workload. During this active recovery period, capillary
blood samples were taken for lactate analysis. The half-life period of lactate elimination
was determined mathematically from the corresponding lactate curves.

Results: Concerning the half-life period of lactate, no significant differences were
found between P and AB (10.6±2.4min vs. 12.2±3.3min).

Conclusion: Despite muscular changes, P seem to have no disadvantages in lactate
elimination after exhaustive exercise compared to AB. The individual fitness level and
genetic predisposition seem to be of higher importance.

57/3 Influence of short-term oral creatine supplementation on 800m
wheelchair performance

Perret C, Mueller G, Knecht H
Institute for Clinical Research, Swiss Paraplegic Centre, CH-6207 Nottwil, Switzerland

Objective: Since arm muscles contain more type II fibres than leg muscles and since
type II fibres have initially a higher phosphocreatine content than type I fibres, it could
be speculated that creatine supplementation would be less efficient for arm exercise.
Independent of this fact, some wheelchair athletes regularly ingest creatine expecting a
better exercise performance. The aim of the present study was to investigate the
influence of short-term oral creatine supplementation on 800m wheelchair performance
in competitive spinal cord injured athletes.

Methods: During two treatment periods, subjects ingested 4x5g creatine monohydrate
or placebo daily, during 6 days in a randomised order. A washout period of 4 weeks lay
in-between the two supplementation periods. Before and after each treatment period
athletes performed an all-out 800m wheelchair test on a training roller. Time to
complete 800m, rate of perceived exertion, lactate concentrations, heart rate and
respiratory parameters were measured. Before each test, body weight was determined.

Results: Times to complete 800m before and after creatine supplementation
(102.8±13.9s vs. 100.5±11.3s) compared to before and after placebo supplementation
(101.6±15.6s vs. 99.5±13.8s) were not significantly different. Moreover, for all other
parameters measured, no significant differences between creatine and placebo
supplementation were found.

Conclusion: A short-term oral creatine supplementation compared to placebo seems
not to enhance performance over 800m in trained, spinal cord injured, wheelchair
athletes. Additionally, results suggest that a possible placebo effect may not be
excluded.

58/3 The individual relationship between heart rate and oxygen uptake in
people with a tetraplegia

Valent L.J.M., Dallmeijer A.J., Slootman J., Janssen T.W.J., Houdijk J.H.P,
Hollander A.P., Woude L.H.V. van der
Rehabilitation centre Heliomare, Wijk aan zee

Introduction
In able bodied persons heart rate (HR) and oxygen uptake (VO2) are lineary related
and therefore training intensity can be prescribed based on HR. In people with
tetraplegia (TP) however, the sympathetic nervous system is disturbed, which may
cause alteration of this VO2-HR relationship. If this relationship appears non-lineair,
then HR is not appropriate to use.

Purpose
To examine the HR-VO2 relationship during progressive handcycling (HC) in persons
with TP.

Methods
The HR-VO2 relationship is determined in a C7/C8 (n=9) and a C5/C6 (n=9) group
during a discontinuous peak capacity HC test. The average HR and VO2-values of the
last minute of each 2min exercise block were used for calculation of the Pearson’s
correlation coefficient (r).

Results
A lineair HR-VO2 relationship is assumed when r > 0.85. For the C7/C8 group r ranged
from 0.85 to 0.99 (mean 0.93 ± 0.04). For the C5/C6 group r ranged from 0.19 to 0.95
(mean 0.74 ± 0.24).

Conclusions
All subjects in the C7/C8 group attained r-values above 0.85 and only a few subjects in
the C5/C6 group. Using HR to monitor training intensity seems reliable in persons with
C7/C8, however this is not the case in the majority of the C5/C6 persons.

59/3 Cinematic parameters in partial body weight-supported treadmill
ambulation using F.E.S.

M.Saccavini, E. Bizzarini, A. Milan.
Ergonomics and Physical Therapy, Spinal Unit, Department of Rehabilitation,
Institute of Physical Medicine and Rehabilitation ,Udine, Italy.

Introduction: head of fibula F.E.S. of the peroneal nerve produces variability of the
lower limbs treble flexion trajectories.

Objective: to describe cinematic gait analysis particularly F.E.S. induced spatial
oscillatory repetitiveness.

Patients: two subjects with complete medium thoracic spinal chronic cord injury.

Methods: cinematic analysis made use of passive markers placed on anterior superior
iliac spine, greater trochanter, lateral meniscus and was carried out while subjects
walked on treadmill with weight bearing system supporting 70% of their body weight.
(TR Spacetrainer) Images referring to 50 oscillatory cycles were acquired from left side
by digital video camera (Canon® DM-MV30E) and then processed by software
(MATLAB® 6.1). F.E.S. was yielded by a programmable 4 channels elettro stimulator
(WinForm® srl, I) and surface electrodes.

Results: when subjects performed an oscillatory cycle on perfectly bidimensional
plane, lower limb described an outline-free movement trajectory.

Conclusions: trajectories spatial definition and distal acceleration peak estimate could
be useful parameters for feedback F.E.S. control supposing that a trajectory describing
an area of constant amplitude was energy saving and that distal acceleration peak
analysis allowed to choose F.E.S. timing.

60/3 Functional electrical stimulation (FES) of long-term denervated
muscles in humans – European “RISE” project

H. Kern*, C. Hofer*, D. Maier**, M. Mödlin*, C. Forstner*, M. Vogelauer, U.
Höllwarth, P. Drewniak, S. Löfler, Wolfgang Richter***, Ugo Carraro****
* Ludwig Boltzmann Institute of Electrostimulation and Physical Rehabilitation,
Department of Physical Medicine, Wilhelminenspital Wien, Austria
** BG Unfallkrankenhaus Murnau, Department of Spinal Cord Injured, Germany
*** Department of Radiology, Wilhelminenspital Wien, Austria
**** Department of Experimental Biomedical Sciences, University of Padua, Italy

A co-operative European research project with the goal to strengthen the scientific
bases of FES therapy of patients with chronic denervation of skeletal muscles. Our
working hypothesis is based on sound knowledge of regeneration capabilities of
satellite cells in long-term denervated skeletal muscles and on the expected additional
contribution of myoblast replication activated by FES training of degenerateddenervated
muscles (DDM).

In our earlier clinical work, we demonstrated that electrical stimulation with exponential
current could slow down atrophy of the DDM. In the European Project “RISE” we show
that a modulated long-term training program restores function up to standing and
walking.

Pre-conditions are a suitable stimulator, sufficient stimulation intensity and an
individually adapted stimulation protocol.

This protocol effectively improves the structural and metabolic characteristics of the
denervated-degenerated muscles. Contractions of whole thigh muscles are elicited by
using anatomically shaped large-size electrodes. Following these procedures trophism
and power of DDM improve even if denervation lasts up to 20 years.

Effectiveness of electrical stimulation protocols of DDM is demonstrated by measuring
contraction force, increase of thigh muscle cross-sectional area. Histological analyses
show marked changes of muscle fiber diameter, content of fat, connective tissue,
sarcomere structure, embryonic myosine and metabolic properties.

61/3 Changes in physical fitness in persons with a spinal cord injury
during and after rehabilitation

JA Haisma, JBJ Bussmann, LHV van der Woude, MP Bergen, TAR Sluis, HJ Stam
Erasmus MC, University Medical Center Rotterdam, The Netherlands

Objective
In persons with a spinal cord injury (SCI) fitness is reduced. Developing prognostic
models will help structured early intervention. Our objective was to analyze longitudinal
change in fitness, and its relation to personal and lesion characteristics.

Method
A prospective study was performed at 8 Dutch rehabilitation centres, with
measurements at start of rehabilitation (t1), three months later (t2), at discharge (t3),
and one year after discharge (t4). Outcome measures were peak oxygen uptake
(VO2peak) and power output (POpeak). Multilevel analysis was used.

Results
206 persons were included.
VO2peak improved significantly from 0,98l/min (t1) to 1,14l/min (t2) and 1,21l/min (t3).
Men and persons with a paraplegia scored higher. After discharge persons with a
tetraplegia improved more.

POpeak improved significantly from 31W ( t1), to 39W (t2) and 44W (t3). Men, younger
persons, persons with incomplete lesions or paraplegia scored higher. During
rehabilitation women improved more. After discharge persons with complete lesions
improved more.

Overall fitness changed non-significantly after discharge.

Conclusion
Fitness is low in SCI and does not significantly change one year after discharge, hence
stimulation of activity programs after discharge seems important in the light of
improving fitness. The varying relationships found warrant further investigation into
determinants of fitness.

62/3 Gross mechanical efficiency of hand rim wheelchair propulsion in
relation to physical capacity and wheelchair skills of persons with spinal cord injury.

S de Groot, AJ Dallmeijer, FWA van Asbeck, A Nene, ELD Angenot, MW Post,
LHV van der Woude
Rehabilitation Center Amsterdam
Institute of Fundamental and Clinical Human Movement Sciences

Purpose
To investigate the relationship between gross mechanical efficiency (ME), as
an indicator of task proficiency, of hand rim wheelchair propulsion and the physical
capacity and wheelchair skills during rehabilitation of persons with (in)complete
paraplegia (PP) and tetraplegia (TP).

Methods
92 Subjects were tested at the start of active rehabilitation, 3 months later,
and when discharged from inpatient rehabilitation. ME was calculated during
submaximal wheelchair exercise. Wheelchair physical capacity was determined by the
peak power output (POpeak). Wheelchair skills were defined as the performance time
of a 15 m sprint and a figure of eight, an ability score and the heart rate reserve
(%HRR) during a set of wheelchair skill tests.

Results
ME showed a significant relationship with POpeak, the ability to perform
wheelchair skills, the performance time and %HRR. Lesion level was identified as a
confounder and, therefore, added to the model.

Conclusion
ME seemed to be an important factor of the physical capacity and
wheelchair skills of persons with SCI during rehabilitation. A higher ME relates to a
higher physical capacity, an increase in the number of wheelchair skills that can be
performed, but also faster performance of the wheelchair skills and at a lower %HRR.

More Abstracts >
< Back to Index