Purpose
There is evidence of complex interaction between vitamin B
12
(vB
12
) level, hyperhomocysteinemia (HyCy), and natriuretic peptide secretion. Exercise training could also modulate such interaction. In this secondary analysis of a Randomized Clinical Trial performed in a chronic obstructive pulmonary disease (COPD) rehabilitation setting, our primary objective was to investigate the interaction between vB
12
supplementation, exercise training, and changes in NT-proBNP levels after 8 weeks of intervention. Secondary objectives were to explore the correlations between acute changes in NT-proBNP levels with (i) acute exercise and (ii) oxygen uptake (
V
’O
2
) kinetics during rest-to-exercise transition.
Methods
Thirty-two subjects with COPD were randomized into four groups: Rehabilitation+vB
12
(
n
= 8), Rehabilitation (
n
= 8), vB
12
(
n
= 8), or Maltodextrin(
n
= 8). They were evaluated at baseline and after 8 weeks, during resting and immediately after maximal exercise constant work-rate tests (CWTs,
T
lim), for NT-proBNP plasmatic levels.
Results
After interaction analysis, the supplementation with vB
12
significantly changed the time course of NT-proBNP responses during treatment (
p
= 0.048). However, the final analysis could not support a significant change in NT-proBNP levels owing to high-intensity constant work-rate exercise (
p
-value > 0.05). There was a statistically significant correlation between
V
’O
2
time constant and ΔNT-proBNP values (
T
lim – rest) at baseline (
p
= 0.049) and 2 months later (
p
= 0.015), considering all subjects (
n
= 32).
Conclusion
We conclude that vB
12
supplementation could modulate NT-proBNP secretion. Moreover, possibly, the slower the initial
V
’O
2
adjustments toward a steady-state during rest-to-exercise transitions, the more severe the ventricular chamber volume/pressure stress recruitment, expressed through higher NT-proBNP secretion in subjects with larger
V
’O
2
time constants, despite unchanged final acute exercise-induced neurohormone secretion.