Trained male cyclists (6 in study 1, 5 in study 2) cycled to exhaustion (EXH) at
75% of VO₂ max twice; once in the non-supplemented (NS) state and once in the vitamin
B-6 (B-6)(20 mg PN) supplemented (S) state. The diet contained 2.3 mg B-6 in study 1
and 1.9 mg B-6 in study 2. Urine was collected during each dietary period. During each
exercise (EX) test, blood was drawn prior to (PRE), one hour during (DX), immediately
after (POST) and one hour after (POST 60) EX and sweat was collected.
Compared to baseline (PRE) levels, plasma pyridoxal 5'-phosphate (PLP) and
vitamin B-6 (PB-6) concentrations increased at DX, decreased at POST, and decreased
below PRE at POST 60 in the NS and S states. EX to EXH in the S state resulted in a
greater increase in PLP DX in study 1 (31% increase vs. 16%) and PB-6 in study 2 (25%
increase vs. 11%) as compared to the NS state. Red blood cell (RBC) PLP significantly
increased from POST to POST 60 in the S state in study 2.
The excretion of urinary 4-pyridoxic acid (4-PA) and urinary B-6 (UB-6) was not
significantly altered by EX to EXH. The mean excretion of 4-PA was significantly greater
in the NS state in study 2 (7.98 ±1.83 mmol/d) as compared to the excretion in study 1
(6.20 ±0.93 mmol/d), whereas the excretion was significantly greater in the S state in study
1 (92.2 ±8.69 mmol/d) compared to the excretion in study 2 (82.7 ±6.16 mmol/d). The percent of B-6 intake excreted as UB-6 (6% in study 1 and 10% in study 2) was
significantly different between the studies in the NS state.
Vitamin B-6 supplementation did not significantly alter the rise in growth hormone
(hGH) concentration seen with EX to EXH. The loss of B-6 in sweat with EX to EXH
was not altered by B-6 supplementation. The loss of B-6 in sweat ranged from 0.0011
mmol to 0.0039 mmol.
Therefore, EX to EXH in the B-6 S state resulted in a greater increase in plasma
PLP and PB-6 DX as compared to the NS state. The decrease in PB-6 and PLP at POST
60 in the S state coincided with a significant increase in RBC PLP, suggesting the
movement of B-6 from the plasma into the RBC at POST 60. EX to EXH and B-6
supplementation did not alter the excretion of 4-PA or UB-6 suggesting that B-6
metabolism was unchanged. The loss of B-6 in sweat was comparable to previously
reported values and was not altered by B-6 supplementation. B-6 supplementation did not
alter the changes in hGH resulting from EX to EXH alone. / Graduation date: 1995
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27256 |
| Date | 04 November 1994 |
| Creators | Dunton, Nancy J. |
| Contributors | Leklem, James E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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