YourBodyLee E Brown, Ed.D., CSCS*D

Hormones and Strength

ormones can be thought of as the

body's messengers. They are

secreted from endocrine glands

into the bloodand travel through-

out the b~ to cause other cells to perform specificfunc-

tions'. These functions are carried out only on the specific

target cellswhich posses the receptors for that hormone. In

this way only the desired outcomeis initiated at the target

cell.

There are two main classificationsof hormones-steroidaland non-steroidal-with each performingseparate functionsat different levels of a target cell. The so-called "sex hor-mones"-estrogen and testosterone-are responsible for

Ace, Gender and StrencthM~s and females are very similar physicallY up to the age ofpuberty (12 - 14 years). After this time the sex hormonesbegin to cause gender differences that eventually lead to amale strength bias. Specifically, testosterone causes anincrease in bone formation and muscle mass, which leads toincreased size in males when compared to females, who. mayposses only approximately 70% of the muscle mass of theirmale counterparts'. This mass difference is most pronouncedin the upper body, where females deposit increased amountsof fat and their strength is thereby only approximately 50 -65% that of males'. In the lower body, strength differencesbetween genders are much less evident when accounting forfat deposits. That is, strength per unit of muscle mass is sim-ilar between genders but still not identicaF. Resistance exer-cise has been shown.to increase the amount of testosteronein the blood and it remains elevated there for more than anhour in trained athletes. However, resistance training doesnot cause the same testosterone elevations in womenl.

For women to bulk up to the level exhibitedin some popular magazines requires the use ofartificial anabolic steroids ...

many changes in the human body and are the primary causefor differences between boys and girls and men and women.Incidentally, they are called the "sex hormones" not becausethey are exclusive to the gender, but because of their relativeconcentrations in each gender. For example, males possestestosterone in amounts 10 - 20 times greater than females3.It is here that we should begin our hormonal journey.

NSCA's Perlormance Training Joumal

Estrogen, on the other hand, is responsible for female sexcharacteristics, and may playa role in the changing strengthexpression of women. Bodyweight has been reported to fluc-tuate as much as two pounds during the menstrual cycle, andthis may affect strength in womenz. However, the absolutestrength of females during the specific phases of the men-strual cycle does not seem to change with different estrogenconcentrations.

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ConclusionIn the final analysis, strength differences between men andwomen can be primarily summed up by the difference inphysical size. However, this size disparity is a function ofgreater concentrations of testosterone in men. Therefore,any fear that women may have regarding bulking up throughresistance training is basically unfounded since they possestestosterone hormonal levels 10 - 20 times less than men.

Essentially, for women to bulk up to the level exhibited insome popular magazines requires the use of artificial anabol-ic steroids such as testosterone injections. Women do adaptto resistance training in similar patterns as men just not tothe same magnitude.

The effect of training on the human muscular system will bethe focus of next issue's column.

{eferences1. Baechle,T.R & Earle, R W (Eds).Essentials of strength

training and conditioning. Champaign, IL: HumanKinetics.2000.

2. Brown, LE. (Ed.). Isokinetics in Human Performance.Champaign.IL: Human Kinetics. 2000.

3. McArdle, WOo, Katch, EI & Katch, Y.L. ExercisePhysiology.Baltimore: Lippincott Williams & Wtlkins.2001.

4. Wilmore, J.H. & Costill, D.L. Physiology of Sport andExercise.Champaign,IL: Human Kinetics.1994

About the AuthorLee E. Brown, EdD., EPC, CSCS, *D,is Assistant Professorand

Directorof theHuman PerformanceLahomtory at ArkansasStateUniversity.He receivedhis Doctorateat Florida AtlanticUniversity. wherehe was Health Sdenres Lab Coordinator.Dr.Brown is a Fellowof theAmerican Collegeof Sports Medicine,aUSA W Certified Club Coach and a Certified Strength andConditioning SpedaUst with Distinction (CSCS,*D) with theNSCA. He will be exploring topics of human physiology eachmonth in this column.

NSCA's Perlormance Training Joumal ~12 Volume1 Number 3 Iwww.nsca-lift.org/perform