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ABSTRACT: Purpose: A complete spinal cord injury (SCI) above the 6 thoracic vertebra (T6) results in the loss of sympathetic innervation of the adrenal medulla. This study examined the effect of a complete SCI above and below T6 on plasma concentrations of epinephrine, circulating interleukin (IL)-6 and other inflammatory cytokines in response to acute strenuous exercise. Methods: Twenty-six elite male wheelchair athletes (8=C6-C7 tetraplegic (TETRA); 10=T6-L1 paraplegic (PARA); 8=non-spinal cord injured controls (NON-SCI)) performed a submaximal exercise test followed by a graded exercise to exhaustion on a motorised treadmill. Blood samples were taken pre-exercise, post-exercise and 30 min post-exercise (post30) and analysed for concentrations of IL-6, IL-10, IL-1 receptor-antagonist (IL-1ra), tumor necrosis factor-alpha (TNF-α), epinephrine and cortisol. Results: Circulating IL-6 concentration was significantly elevated at post-exercise and post30 (∼5-fold) in NON-SCI and PARA (P=0.003) whereas concentrations in TETRA did not change significantly from pre-exercise values. IL-10, IL-1ra and TNF-α were unaffected by exercise in all groups, however both SCI groups presented elevated concentrations of IL-10 compared with NON-SCI (P=0.001). At post-exercise, epinephrine concentrations were significantly higher than pre-exercise and post30 concentrations in NON-SCI (∼3-fold) and PARA (∼2-fold) (P=0.02). Plasma epinephrine concentrations were unchanged in TETRA throughout exercise; concentrations were significantly lower than NONSCI and PARA at all-time points. Plasma cortisol concentrations were significantly elevated in all groups at post-exercise and post30 compared with pre-exercise (P<0.001). Total exercise time was similar between groups (NON-SCI= 38±6; PARA= 35±5; TETRA= 36±5 min). Conclusion: These findings suggest the sympathetic nervous system plays an important regulatory role in the circulating IL-6 response to exercise and has implications for the metabolic and inflammatory responses to exercise in individuals with injuries above T6.
Medicine and science in sports and exercise 03/2013; · 3.71 Impact Factor
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ABSTRACT: The volume of literature on field-based physiological testing of wheelchair sports, such as basketball, rugby and tennis, is considerably smaller when compared with that available for individuals and team athletes in able-bodied (AB) sports. In analogy to the AB literature, it is recognized that performance in wheelchair sports not only relies on fitness, but also sport-specific skills, experience and technical proficiency. However, in contrast to AB sports, two major components contribute towards 'wheeled sports' performance, which are the athlete and the wheelchair. It is the interaction of these two that enable wheelchair propulsion and the sporting movements required within a given sport. Like any other athlete, participants of wheelchair sports are looking for efficient ways to train and/or analyse their technique and fitness to improve their performance. Consequently, laboratory and/or field-based physiological monitoring tools used at regular intervals at key time points throughout the year must be considered to help with training evaluation. The present review examines methods available in the literature to assess wheelchair sports fitness in a field-based environment, with special attention on outcome variables, validity and reliability issues, and non-physiological influences on performance. It also lays out the context of field-based testing by providing details about the Paralympic court sports and the impacts of a disability on sporting performance. Due to the limited availability of specialized equipment for testing wheelchair-dependent participants in the laboratory, the adoption of field-based testing has become the preferred option by team coaches of wheelchair athletes. An obvious advantage of field-based testing is that large groups of athletes can be tested in less time. Furthermore, athletes are tested in their natural environment (using their normal sports wheelchair set-up and floor surface), potentially making the results of such testing more relevant than laboratory testing. However, given that many tests, such as the multistage fitness test and the Yo-Yo intermittent test, have originally been developed for AB games players, the assumption that these can also be used for wheelchair athletes may be erroneous. With the array of AB aerobic and anaerobic field tests available, it is difficult to ascertain which ones may be best suited for wheelchair athletes. Therefore, new, wheelchair sport-specific tests have been proposed and validated. Careful selection of tests to enable coaches to distinguish between disability classifications, wheelchair proficiency and actual performance improvements is paramount as this will not only enhance the value of field-based testing, but also help with the development of meaningful normative data.
Sports Medicine 12/2012; · 5.16 Impact Factor
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ABSTRACT: The purpose of this study was (1) to examine the value of a verification phase (VER) in a peak testing protocol and (2) to assess the reliability of peak physiological variables in wheelchair athletes. On two separate days, eight tetraplegic (TETRA), eight paraplegic (PARA) and eight non-spinal cord-injured (NON-SCI) athletes performed treadmill ergometry, consisting of a graded exercise test to exhaustion (GXT) followed by a VER. Peak oxygen uptake [Formula: see text] was compared (1) between GXT and VER and (2) between test days. [Formula: see text] did not differ between GXT and VER (P = 0.27), and coefficients of variation between GXT and VER were in the range of 2.9 and 6.4 % for all subgroups. Coefficients of variation of [Formula: see text] between test days were 9.3 % (TETRA), 4.5 % (PARA) and 3.3 % (NON-SCI). It is therefore concluded that whilst a VER can be used for a more robust determination of [Formula: see text], a deviation of up to ~6 % between GXT and VER should be considered as acceptable. For between-day analyses, relatively large changes in [Formula: see text] are required to confirm "true" differences, especially in TETRA athletes. This may be due to their lower aerobic capacity, which results in a larger relative variation compared with the other subgroups.
Arbeitsphysiologie 06/2012; · 2.15 Impact Factor
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ABSTRACT: The purpose of this investigation was to examine the use of subjective rating of perceived exertion (RPE) as a tool to self-regulate the intensity of wheelchair propulsive exercise in individuals with tetraplegia. Eight motor complete tetraplegic (C5/6 and below; ASIA Impairment Scale = A) participants completed a submaximal incremental exercise test followed by a graded exercise test to exhaustion to determine peak oxygen uptake ([Formula: see text]) on a wheelchair ergometer. On a separate day, a 20-min exercise bout was completed at an individualised imposed power output (PO) equating to 70 % of [Formula: see text]. On a third occasion, participants were instructed to maintain a workload equivalent to the average RPE for the 20-min imposed condition. [Formula: see text], heart rate (HR) and PO were measured at 1-min intervals and blood lactate concentration [BLa(-)] was measured at 0, 10 and 20 min. No differences (P > 0.17) were found between mean [Formula: see text], % [Formula: see text], HR, % HR(peak), [BLa(-)], velocity or PO between the imposed and RPE-regulated trials. No significant (P > 0.05) time-by-trial interaction was present for [Formula: see text] data. A significant interaction (P < 0.001) for the PO data represented a trend for an increase in PO from 10 min to the end of exercise during the RPE-regulated condition. However, post hoc analysis revealed none of the differences in PO across time were significant (P > 0.05). In conclusion, these findings suggest that RPE can be an effective tool for self-regulating 20 min of wheelchair propulsion in a group of trained participants with tetraplegia who are experienced in wheelchair propulsion.
Arbeitsphysiologie 05/2012; · 2.15 Impact Factor
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ABSTRACT: Altered autonomic innervation in tetraplegic individuals has been shown to depress certain immune parameters at rest and alter exercise-related salivary immunoglobulin A (sIgA) responses. The purpose of this study was to examine resting sIgA responses as a function of training load and episodes of upper respiratory symptoms (URS) in elite tetraplegic athletes.
Resting saliva samples were obtained from 14 tetraplegic athletes at 12 predefined time points over 5 months and analyzed for sIgA. Occurrence of self-reported URS and training load was recorded throughout the study's duration. Regression analyses were performed to investigate the relationship between sIgA responses and training load. Furthermore, the relationships between sIgA responses and URS occurrence were examined.
sIgA secretion rate was negatively correlated with training load (P=.04), which only accounted for 8% of the variance. No significant relationships were found between sIgA responses and subsequent URS occurrence. Finally, sIgA responses did not differ between athletes with and without recorded URS during the study period.
In line with findings in able-bodied athletes, negative relationships between sIgA secretion rate and training load were found in tetraplegic athletes. This may explain some of the higher infection risk in wheelchair athletes with a high training load, which has been previously observed in paraplegic athletes. However, the nonsignificant relationship between sIgA responses and URS occurrence brings into question the use of sIgA as a prognostic tool for the early detection of URS episodes in the studied population.
International journal of sports physiology and performance 12/2011; 7(3):210-7. · 1.80 Impact Factor
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ABSTRACT: The study's purpose was to examine salivary secretory immunoglobulin A (sIgA) responses and α-amylase activity after constant load and intermittent exercise in elite wheelchair athletes.
Twenty-three wheelchair athletes divided into three groups (eight tetraplegic (TETRA), seven paraplegic, and eight non-spinal cord-injured) performed two randomized and counterbalanced 60-min sessions on a treadmill. These consisted of constant load (60% peak oxygen uptake) and intermittent (80% and 40% peak oxygen uptake) exercise blocks. Timed unstimulated saliva samples were obtained before, mid, after, and 30 min after exercise and analyzed for sIgA and α-amylase. Furthermore, oxygen uptake, blood lactate concentration, and RPE were measured during both sessions.
SIgA secretion rate and α-amylase activity were increased during exercise in all groups (P < 0.05). However, the increase of sIgA secretion rate during exercise was greater in TETRA individuals (postexercise average data for both trials in comparison with preexercise data: TETRA = +60% ± 31%, paraplegic = +30% ± 35%, non-spinal cord-injured = +11% ± 25%; P < 0.05). Yet, groups were comparable with respect to blood lactate concentration and RPE for both exercise sessions.
Despite the disruption of autonomic salivary gland innervation in TETRA athletes, their ability to increase sIgA secretion rate seems comparable to wheelchair athletes with intact autonomic salivary gland innervation. The similar responses between groups may stem from sympathetic reflex activity during exercise or a predominant contribution of parasympathetic activity, which are still intact systems in the TETRA population. The results of this study support the positive role of acute exercise on oral immune function in wheelchair athletes independent of disability type.
Medicine and science in sports and exercise 01/2011; 43(8):1414-21. · 3.71 Impact Factor
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ABSTRACT: A respiratory warm-up (RWU) can improve exercise performance in able-bodied athletes. However, its effects in paraplegic individuals are unknown. On two occasions, nine male active paraplegic individuals performed an arm cranking test to exhaustion at 85% of their peak power output. In the intervention (INT) trial, this procedure was preceded by a RWU, whereas in the control (CON) trial, no RWU was conducted. Time to exhaustion was reduced following the RWU (CON vs. INT: 497 ± 163 vs. 425 ± 126 s, P = 0.02). Pulmonary ventilation was increased in the middle (74.8 ± 18.0 vs. 78.3 ± 19.6 L min(-1), P = 0.01) and end (86.1 ± 20.4 vs. 95.4 ± 23.3 L min(-1), P = 0.01) phase of exercise following the RWU. Forced expiratory volume in 1 s (FEV1) was reduced following the RWU (3.44 ± 0.45 vs. 3.27 ± 0.54 L, P = 0.02). The decrease in FEV1 following the RWU and the higher pulmonary ventilation during the INT trial suggest that the RWU fatigued the respiratory system, and hence reduced performance capacity. It is possible that the RWU used in this study is not suitable for paraplegic individuals, as their respiratory system is limited due to their disability. We conclude that a RWU impaired exercise performance in a group of active paraplegic individuals as a result of respiratory muscle fatigue.
Arbeitsphysiologie 12/2010; 110(6):1291-8. · 2.15 Impact Factor
