Dietary

Dietary carbohydrate, performance during
11 ‘i/ham
ABSTRACT diets on muscle

muscle glycogen, 7 d of training13
Do’le, David R La,nb, and Richard
centration cyclists uncertain This hydrate cogen,

and exercise
H Strauss
on training (3). study was designed body wt1
and
.

M Sherman,
The glycogen

J Andrew
effects and

of moderateperformance

or high-carbohydrate in runnersand

and

exercise to compare wt’.d’)

performance the and maximal effects highdiets

capabilities of moderate(10 on g carbomuscle
training.

is

over 7 consecutive days biopsies were performed
I h at

of training were determined. Muscle on 4 separate days before exercise for consumption training at 80% maintained session peak V02 with
<

(5 g carbohydrate’kg
.

75i) sprints.and

peak

oxygen After the was

(V02)

followed

by five, ran for

kg body

d

‘) carbohydrate and

glycapa-

1-mm or cycled cyclists

on day
. Muscle

7, subjects glycogen

training

compliance,

performance

to exhaustion runners

bilities of runners

cyclists over

7 d of intense

the high-carbohydrate with the all training moderatesessions. 7. MethodsSubjects Thirty-six informed subject study. Human versity. men volunteered according an honorarium to serve as subjects and provided Each in the

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diet but was carbohydrate and For

reduced 30-36% diet. All subjects

(P

0.05)

completed

there were no differences in times to exhaustion on day cyclists and runners. consuming amoderate-carbohydrate

diet over 7 d of intense training reduces muscle glycogen but has no apparent deleterious effect on training capability or highintensity exercise performance. A high-carbohydrate diet maintains muscle ing capability glycogen. but this or high-intensity
1993:57:27-31.

consent was paid

to institutional for their

guidelines. participation

has no apparent benefitexercise performance.

on trainAm J

This project was approved by the Biomedical Subjects Review Committee of The Ohio Subjects’ those also was previous imposed required weekly to achieve training a V02 characteristics weighing loads peak were by the experimental

Sciences, State Unisimilar to Each for

C/in Nutr
KEY

or exceeded WORDS Physical exertion. athletic training, exercise subjectthe Introduction Endurance ygen consumption exercise at intensities substantially 70-80% lowers of maximal muscle oxare applicable The physical provided

protocols. 4 L/min of the was used

exercise mode. and physiological in Table 1. Hydrostatic

subjects to de-

(VOmax)

glycogen

termine phase.

lean body mass of the subjects on day 1 of the control Vital capacity was used toestimate residual volume (6). and hydrostatic of the readings were averaged, weighing was 4%. and the VO2) that

concentrations ( 1 ). Associated with reduced muscle glycogen is the inability to maintain exercise intensity at 70-80% VO2max ( I ).It is usually assumed that muscle glycogen must be restored between
pabilities

Repeated measures of vital capacity were determined until the variabilityThe Siri means for the three highest values equation (7) was used to calculate Exercise mode-specific peak oxygen was determined by using a progressive also allowed determination maximal heart rate. V02 open-circuit volumes Equipment, (Warren were system measured Wilton, E Collins, VT) Boston). that was with

daily

training

sessions content Costill declined

to facilitate ofathletes’over diets

optimal affects that

training muscle muscle diet. those

caglyglyIn

(2. 3). et al (4) reported 3 consecutive a 43% glycogen over

The cogen cogen training spite

carbohydrate concentration. progressively when of the subjects 43%

percent body fat. consumption (peak workload protocol

d of running days, of trainof a

of the ventilatory determined with V02 against...