Defense Technical Information Center

4 downloads 576 Views 905KB Size Report
Feb 15, 1990 - medications or had a history of endocrine disorders. The ... 11/780, Digital Equipment Corporation, Maynard, MA) system which allowed ...

N effects

The

high

of

intensity cycle

exercise on

Kraemer,

Charles J.

Hannan, Thomas Kettler,

Joseph E.

Dziados,

A.

John F.

response patterns

William J.

Everett

DTIC

un L E C T E 'u- FEB 15 1990

1%

sympath-adrenal-medullary

(

COX

~FIc1LE.

Andrew C.

Patton, Howard G. Scott

E.

Fry, Peter N.

SD

Knuttgen,"

'N-

Gordon,.. Frykman, and

Harman

) Exercise Physiology Division, U.S. Environmental

Army Research

Investigation, Madigan Army Medical

WA

and Center for

98431

Sports Medicine,

University, University Park, PA

Running Head:

Department

Medicine, Natick, MA 01760-5007,

Clinical

Peptide F

responses

of

Center, Tacoma,

The Pennsylvania State

16802

to high

Institute of

U.S.A.

intensity cycle

exercise

Address

(

Correspondence

Approved for public rees

Distnbution Lnimjted -_

-,

to:

William J.

Kraemer,

Center

Sports Medicine

for

Ph.D.

Greenberg Sports

Complex

The Pennsylvania

State University

University

Park,

'".r. ; .

PA

16802

.

2 ABSTRACT

PPlasma proenkephalin Peptide F immunoreactivity (ir)

and

catecholamines were examined before and after maximal exercise to exhaustion at four

intensities [36,

55, 73 and 100% maximal

leg

power (MLP)] by means of a high resistance cycle ergometer.

All

intensities were greater than those eliciting peak O2 uptake for the individual subjects.

Blood samples were obtained immediately

after exercise and at 5 and 15 min post-exercise.1 (p < 0.05)

Significant

increases in plasma Peptide F ir were observed

immediately following exercise at 36% MLP.

Significant

increases

in plasma epinephrine were observed immediately following exercise at 36% 100% MLP.

and 55% MLP and at 15 min following exercise at

Significant increases for plasma norepinephrine were

observed immediately following exercise (36, MLP),

55, 73,

and 100%

5 min after exercise (36, 55, and 73% MLP) and 15 min

following exercise (36% MLP).

Increases in whole blood lactate

were observed at all points post-exercise for 36,

55, and 73% MLP

and at 5 min post-exercise for 100% MLP exercise intensity. These data show that brief, high intensity exercise results in differential response patterns of catecholamines and proenkephalin Peptide F ir.

A These data suggest that exercise-

or

induced increases may be the result of non-colinear storage and

Il

3 release mechanisms

in the adrenal medulla.

:td

K1ey Words: proenkephalins, opioid peptides, epinephrine, norepinephrine, anaerobic exercise, skeletal muscle morphology 4 Dist

0 0

bility Codes acidor

Special

3

Many studies intensities

have demonstrated that

ranging from submaximal

endurance exercise at

to peak 02 uptake stimulates

the sympatho-adrenal-medullary system as evidenced by increases in plasma catecholamines (10,13,17,19,21,28,29,31,33,36). clear,

however,

Less

are the exercise-induced responses of

preproenkephalin peptides found in the adrenal-medullary chromaffin cells which have been shown to be responsive same stimuli examining (i.e.

that

induce epinephrine

the smallest

to the

release (18,31,40).

Studies

preproenkephalin biosynthetic end-products

methionire-enkephalin and leucine-enkephalin)/have

typically demonstrated no significant increases above rest endurance exercise stress

(10,23).

after

Conversely, increases above

rest have been observed for larger preproenkephalin fragments (e.g. Peptide F)

consequent to graded exercise

While receiving greater attention, only

(24,25,27).

limited data concerning

the adrenal-medullary responses to short-term, high intensity exercise (greater than peak 02 uptake) are available. studies

have demonstrated significant

Previous

exercise-induced increases

in plasma epinephrine and norepinephrine following short-term exercise

tasks ranging

interval

runs

has ever

been made

peptide (i.e. intensities at

from a 20 sec sprint

(6,12,19,39).

Still,

to repetitive

to our knowledge, no attempt

to examine catecholamine and preproenkephalin

Peptide F)

responses to a wide range of

very high power outputs.

containing polypeptides (ECPs)

exercise

Since enkephalin-

are responsive to

the same stimuli

4 that

induce epinephrine secretion, it was hypothesized that ECPs

would be responsive to high primary purpose of alterations (107-140)]

intensity exercise stress.

this study was

of maximum.

the

to examine the plasma

of catecholamines and Peptide F at maximal

Thus,

[preproenkephalin-

power production and at various percentages

These data will

adrenal-medullary responses

enhance the understanding of to high-intensity exercise.

METHODS Subiects.

Nine normally active, healthy men provided written

informed consent prior

to

their participation.

All were

medically screened by a physician, and none were taking any medications or had a history of endocrine disorders. subjects' physical characteristics were

(mean ± 1SD):

± 4.0 yr;

height,

body

14.8 + 4.9; maximal 02 uptake (VO2nax),

fat,

178.5 + 5.0 cm;

The

weight,

78.9

7.3

+

age,

23.9

kg; percent

47.3 ± 7.7

ml'kg-l'min-l. Subjects were thoroughly familiarized with all equipment and procedures prior body density

(11,41)

to taking part.

and VO2max(7,

32

testing Measurements of

) were made approximately two

weeks before the determination of maximal These methods have beepcribedin

Muscle biopsy Procedures and analyses.

power production. detail (26).

To examine

the

relationships between skeletal muscle morphological characteristics and peripheral muscle biopsy samples

blood hormonal

concentrations,

were obtained approximately

10 days prior

5 to maximal

power

testing.

from the superficial the dominant

Muscle

tissue samples were obtained

portion of the vastus

lateralis muscle of

leg utilizing the percutaneous

needle biopsy

technique of Bergstrom (3) as modified by Evans et al. Special all

subjects

repeat and

care was

taken

to approximate

the same biopsy location in

using a depth of approximately 2 cm.

biopsies

(9).

Pafa from

(randomly performed) demonstrated nonsystematic

insignificant

interbiopsy variations

in fiber-type

?

distributions.