Title: Do wheelchair-bound people need to exercise as Paralympic athletes to be healthy?
Julia Baumgart1, Gertjan Ettema1, Berit Brurok2, Øyvind Sandbakk1
1
Centre for Elite Sports Research, Department of Neuroscience, Norwegian University of Science and
Technology, Trondheim, Norway
2
Department of Physical Medicine and Rehabilitation, St. Olav’s University Hospital, Trondheim,
Norway
Abstract
In Norway, approximately 10% (574.000) of the population have a disability and of these 8% (50.000)
are estimated to be wheelchair bound, every tenth person (5000) due to a spinal cord injury (SCI). As
compared to the general able-bodied population, risk of morbidity and mortality is increased in
persons with a SCI. The most common cause of death is respiratory and cardiovascular diseases (CVD),
and SCI-related lifetime costs range from 1 to 2.3 million euro per person with SCI.
Being physically active and thereby increasing cardio-respiratory fitness is of major
importance in preventing CVD in persons with a SCI. Peak aerobic capacity (VO2peak) is a common
indicator of cardio-respiratory fitness that is highly associated with risk of mortality from CVD. Even in
Paralympic athletes who supposedly are the most physically active individuals in the SCI population
and have relatively high VO2peak, the prevalence of cardiovascular abnormalities is 12%. Athletes
competing in Nordic sit skiing and hand-cycling, which are the sports with the highest aerobic
endurance demands, still have considerably low VO2peak values (46 ± 5 and 36 ± 4 mL∙kg-1∙min-1).
To understand the effects of exercise training on VO2peak, reliable and valid tests concepts need
to be developed. When Paralympic sitting athletes perform incremental exhaustive exercise in an
upper-body mode, two factors mainly influence VO2peak: 1) the upper-body mode itself activates a
relatively low muscle mass and consequently does not fully tax the cardio-respiratory system and 2)
the impact of an individual’s disability on movement function and physiological capacity. We found
that as compared to a group of similarly upper-body trained able-bodied controls, VO2peak values are
lower in Paralympic sitting athletes with a SCI due to their disability-related limitations. This is likely
related to blood pooling in the legs and the abdomen, autonomic dysfunction and a negative effect of
exercising with a limited muscle mass on the heart. However, the effect of different disabilities,
training status and test modes on VO2peak should be further looked into.
To systematically improve cardio-respiratory fitness and sports performance, Paralympic and
Olympic athletes train with different exercise intensity zones, which are normally based on the aerobic
and anaerobic threshold concepts. However, it is not clear yet whether the exercise intensity zones of
able-bodied athletes can be used interchangeably in Paralympic sitting athletes, as we found the latter
to, for example, display considerably higher blood lactate responses and lower heart rates at the same
subjective exercise intensity. Furthermore, if the current concepts of defining the anaerobic threshold
reflect maximum sustainable performance in the latter, needs further investigation.
For persons with a SCI, knowledge on Paralympic athletes approaching the upper limits of
cardio-respiratory fitness provides a context of what is achievable, and their training data provides
knowledge on how this is achieved. However, even in highly trained Paralympic sitting athletes there
seem to be limitations in cardio-respiratory fitness. Overall, Paralympic sitting athletes have an
increased cardio-respiratory fitness and a decreased CVD risk as compared to their un-trained peers,
suggesting that large amounts of training are needed to maintain health. However, what type and
amount of training is needed to further increase cardio-respiratory fitness and improve health in both
Paralympic athletes and their untrained peers, remains to be investigated.