Four young trained men were studied during 50 min of continuous
bicycle ergometer exercise [30 min at 60%, 15 min at 80%,
and 5 min at 90% maximal heart rate (MHR)] to elucidate changes
in fuel metabolism resulting from a glycogen depletion-repletion
regimen, and to determine the effect of supplemental vitamin B-6
(B6). The diets were: Week 1, 40% CHO normal diet (NC); Week 2,
days 1-3 CHO 11% (LC), days 4-7 CHO 71% (HC); Week 3, same as week
2 but with an 8 mg B6 supplement each day (LC+B6, HC+B6). The men
exercised after an overnight fast on days 4 and 7, upon completing
the depletion or repletion phase. Blood was collected before
exercise (PRE), during the 80% MHR work (DURING), immediately
after completion of the 90% MHR work (POST), and 30 min and 60
min after exercise (30 MIN POST, 60 MIN POST).
Plasma FFA concentrations were from 30% to 75% higher (p<0.05)
after the LC and LC+B6 diets than after the NC-1, NC-2, HC, or
HC+B6 diets, and B6 did not appear to affect plasma FFA levels.
Plasma glucose values were from 3% to 4% lower (p<0.01) for DURING
HC and HC+B6 than DURING NC-1. Since plasma HC and HC+B6 lactate
values were 57% higher (p<0.05) than DURING control values, the
simultaneously low glucose and high lactate levels indicate that
glucose was primarily derived from muscle glycogen in the HC and
HC+B6 conditions. Addition of B6 to the HC diet resulted in
elevated POST lactate levels, but this difference was not significant.
LC glucose and lactate values did not differ significantly
from control values. However, PRE LC+B6 glucose values
were 12% lower than PRE control values (p<0.02) and continued to
be lower during exercise. POST and 30 MIN POST LC+B6 values were
47% lower than the LC values (p<0.005 and p<0.01, respectively).
The glucose and lactate data indicate that B6 supplementation does
alter CHO metabolism when added to a glycogen depletion-repletion
regimen. Due to the possible role of glycogen phosphorylase as
an expanding depot for B6 storage, supplementation with B6 may
cause a more rapid emptying of muscle glycogen stores and a
reduction of athletic endurance. / Graduation date: 1983
| Identifer | oai:union.ndltd.org:ORGSU/oai:ir.library.oregonstate.edu:1957/27157 |
| Date | 21 May 1982 |
| Creators | DeVos, Ann |
| Contributors | Leklem, James E. |
| Source Sets | Oregon State University |
| Language | en_US |
| Detected Language | English |
| Type | Thesis/Dissertation |
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