Submaximal Exercise Does Not Increase Brain-Derived Neurotrophic Factor (BDNF) In People With Spinal Cord Injury
Bibliographic record
Abstract
Brain-derived neurotrophic factor (BDNF) has been implicated in repair and regeneration of peripheral neurons, and is important for brain health. Acute exercise (EX) increases circulating BDNF in an intensity dependent manner in able-bodied individuals. However, the response of BDNF to EX in people with spinal cord injury (SCI) is poorly understood. PURPOSE: to investigate the hypothesis that submaximal EX will increase serum and plasma BDNF in people with SCI. METHODS: Nine adults with SCI participated (M age = 39.2 ± 11.0 years; M years post-injury = 16.5 ± 9.2). After completing a maximal exercise test on an electromagnetically braked arm-crank ergometer to determine peak power output (PPO), participants completed two visits in randomized order: 1) submaximal EX (30 minutes maintaining 55-65 rpm @ 60% PPO); and 2) seated control (CTL). Ratings of perceived exertion (RPE) were measured during EX using the 6-20 visual Borg RPE scale. Heart rate (HR) and blood pressure (BP) were measured pre- and post-EX. BDNF was measured via ELISA in both serum and plasma from venous blood sampled at pre-, post-, and 90 min post-EX. For the CTL visit, participants rested quietly for 120 min and blood was sampled at equivalent time points to EX. A 2-factor repeated measures ANOVA was computed to assess BDNF responses by time and condition. Paired t-tests were computed to assess HR and BP responses to EX. Pearson correlations were computed to explore relationships between BDNF and physiological responses to EX and work rate. RESULTS: The average EX work rate was 47 ± 17 W and RPE was 13 ± 1. HR increased by 26 ± 33 bpm (+41%; p=0.059), whereas systolic and diastolic BP remained unchanged after EX. Contrary to our hypotheses, EX had no effect on serum (Pre vs. Post-EX = 22447.9 ± 9071.1 pg/mL vs. 26552.8 ± 6563.4 pg/mL; F(1,12) = 0.51, p=0.53) or plasma (Pre vs. Post-EX = 1802.7 ± 1031.1 vs. 1662.7 ± 1390.0 pg/mL; F(1,10) = 0.77, p=0.45) BDNF. Exploratory correlational analyses showed no relationships between changes in BDNF and the outlined parameters. CONCLUSIONS: Submaximal EX did not increase BDNF in people with SCI. Future studies should systematically investigate BDNF responses to higher EX intensities given the intensity-dependent response in able-bodied people. FUNDING: Rick Hansen Foundation through the Blusson Integrated Cures Partnership.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.001 | 0.000 |
| Insufficient payload (model declined to judge) | 0.002 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".