Brain-derived neurotrophic factor concentrations in tetraplegic athletes.

STUDY DESIGN: A prospective cohort with acute tetraplegia. OBJECTIVE: The purpose of this study was to investigate acute changes in serum brain-derived neurotrophic factor (BDNF) concentrations in tetraplegic spinal cord-injured (SCI) athletes during a typical training session of wheelchair rugby. SETTINGS: German Sport University Cologne, Cologne, Germany. METHODS: Eleven male SCI (AIS A and B) athletes completed a 90-min training session: The warm-up period included continuous pushing, submaximal increasing sprints and agility drills. The main training section comprised ball handling, passing drills, scrimmage activity and tactical practice. At the end of the training session, the athletes did moderate continuous pushing as a short cool-down. Venous blood samples were taken at rest before exercise, after the warm-up period and immediately following the first part of the main training section. Serum was pipetted after 30 min of blood sample resting and a subsequent centrifugation. BDNF concentrations were measured using an enzyme immunoassay ELISA kit. RESULTS: Heart rate (P < 0.01) and lactate (P = 0.04 and P < 0.01) concentration differed significantly in warm-up and main training part in comparison with basal values at rest. At rest, BDNF concentrations were 33.2 ± 21.6 ng ml(-1), after warm up 31.9 ± 18.9 ng ml(-1) and after the training session 29.9 ± 11 ng ml(-1), without significant differences (P > 0.05). CONCLUSIONS: A typical wheelchair rugby training session does not affect basal serum BDNF concentration in elite SCI athletes. In comparison with concentrations previously reported in healthy subjects, the current values at rest were slightly higher or rather at the upper limit.

The spirografic oxygen deficit: its role in cardiopulmonary exercise testing.

The increase in oxygen uptake > 100 ml · min-1 during steady state exercise when elevating the inspired fractional air content (FinO2) from 0.21-1.00 defines the "spirografic oxygen deficit" (SOD). The purpose of this study was 2-fold: 1) determine the SOD at different exercise intensities in healthy participants and 2) investigate if a correlation exists among key variables of cardiopulmonary exercise testing. 12 men (24±2 yrs; 183±4 cm; 83.5±5.3 kg) performed cycle tests to determine maximal power output (Pmax), the power output at the first (PVT1) and the second ventilatory threshold (PVT2), at 4 mmol · l-1 blood lactate (P4) and lactate threshold (PLT). When cycling at 30, 40, 50, 60, 70 and 80% Pmax, the FinO2 was increased from 0.21-1.00 after 5 min to assess the power output at the SOD and at which blood lactate increased > 1 mmol∙L-1 (PLLAC). The SOD occurred at 70% Pmax accompanied by increased blood lactate concentration (p<0.01). The PSOD correlated with PLACC (p=0.05; r=0.61), but not with PVT1, PVT2, P4, or PLT (best p=0.29; highest r=0.39). In conclusion, the SOD may represent a non-invasive tool for evaluating submaximal endurance performance, especially when evaluating the peripheral contribution to performance.