Learn More About The Role of Individual Hormones in Your Health
Here we touch on some of the significant points related to specific hormones. This reference is useful when choosing the multiple hormone test kits. You may also like to check the symptoms pages
- ESTRONE E1
- ESTRADIOL E2
- ESTRIOL E3
Androstenedione is a type of Androgen Sexual Steroid Hormone produced by the Hair Follicles, male Testes and (in much lesser quantities) by the female Ovaries. It is also produced in lesser quantities by (both the male and female) Adrenal Cortex of the Adrenal Glands. Androstenedione is regarded as a weak Androgen as it does not exert physiological effects to the same extent as the major Androgens.
Health Benefits of Supplemental Androstenedione
- Supplemental Androstenedione may improve Athletic Performance.
- Supplemental Androstenedione increases (subjective feelings of) Energy.
- Supplemental Androstenedione may facilitate Muscle Growth:
- Androstenedione may stimulate Muscle Growth in its “own right” – in addition some supplemental
- Androstenedione is converted within the body to Testosterone which is a well-established initiator of
- The ability of Androstenedione to cause Muscle Growth is limited (rate-limited) by the availability of the necessary enzyme that catalyzes this conversion of Androstenedione to Testosterone.
- Supplemental Androstenedione may increase Muscle Strength.
- Supplemental Androstenedione helps to prevent Osteoporosis in women who have had an ovariectomy:
- Removal of the Ovaries causes a reduction in endogenous Androstenedione production and this causes subsequent Bone loss.
- Supplemental Androstenedione may improve Memory – especially Short Term Memory (this effect occurs via the conversion of Androstenedione to Testosterone, a known enhancer of Memory).
- Supplemental Androstenedione may improve Mood. research
- Supplemental Androstenedione (taken approximately 30 – 60 minutes prior to intended sexual activity) has been reported to increase Sexual Desire in some people (this effect is believed to occur from the conversion of Androstenedione to Testosterone).
- Supplemental Androstenedione increases the body’s Estradiol levels – caution excessive Estrone is associated with various toxic side effects.
- Small amounts (1 – 5%) of Androstenedione are converted (by the P-450 Aromatase Enzyme) within peripheral tissues (e.g. Adipose Tissue) to Estrone:
- Supplemental Androstenedione (300 mg per day) causes a significant increase in the body’s Estrone levels – caution excessive Estrone is associated with various toxic side effects.
- Androstenedione is the immediate precursor for the endogenous production of Testosterone.
- Cortisol is a type of Adrenal Glucocorticoid Hormone (Corticosteroid) manufactured by the (zona fasciculata and zona reticularis of the) Adrenal Glands.
- Cortisol helps to control Allergies (by stabilizing Lysosomes).
- Cortisol significantly inhibits Inflammation (via several mechanisms):
- Cortisol stabilizes the Cell Membranes of Lysosomes.
- Cortisol decreases the permeability of Capillaries (resulting in less Blood Plasma and fewer Cells entering areas of Inflammation).
- Cortisol suppresses the activity of Phagocytes.
- Cortisol suppresses the synthesis of several endogenous compounds involved in Inflammation (including Interleukin 1 and Tumor Necrosis Factor-a).
Dehydroepiandrosterone Sulfate is a type of Steroid Sexual Hormone Precursor.
- DHEAS is chemically similar to Dehydroepiandrosterone (DHEA) except for the inclusion of Sulfate in this molecule – DHEAS is predominantly water-soluble, whereas DHEA is predominantly fat-soluble. It is produced in and secreted by the zona fasciculata and zona reticularis of the Adrenal Glands.
- DHEAS possesses Life Extension possibilities: The death rate for people who naturally have high levels of DHEAS is lower than for those with reduced levels of DHEAS.
- Higher than average levels of DHEAS are associated with a reduced mortality rate from Cardiovascular Diseases:
- DHEAS suppresses the proliferation of the Cancer cells involved in Pancreatic Cancer (by inhibiting the Glucose-6-Phosphate Dehydrogenase (G6PD) enzyme).
- DHEAS alleviates Amnesia.
- DHEAS enhances the function of Glial Cells (it improves their survival rate).
- DHEAS enhances the release of Acetylcholine from the Hippocampus.
- DHEAS enhances Long Term Memory.
- DHEAS facilitates the survival of Neurons.
The body’s levels of DHEAS decline in tandem with the progression of the Aging Process – by the age of 70, DHEAS levels in most people have declined to approximately 20% of their peak levels
Dihydrotestosterone is a Hormone that is an oxidation product of Testosterone.
Toxic Effects of Dihydrotestosterone
- Dihydrotestosterone causes Hair Follicles to go into resting phase which results in Male Pattern Baldness –
- Dihydrotestosterone is manufactured endogenously in the Sebaceous Glands and then attaches to and shrinks the Hair Follicle, reducing the diameter of the hair shaft and restricting the nutrient supply to the Hair. The underlying mechanism for this process is that the body’s Immune System treats the
- Dihydrotestosterone that has attached to the Hair Follicle as an Antigen (i.e. as a foreign body) and begins to destroy the Hair Follicle, subsequently causing Hair Loss.
- Dihydrotestosterone (paradoxically) accelerates the development of Hirsutism (i.e. excessive body Hair growth especially on the Back and from the Ears).
- Binding of Dihydrotestosterone (DHT) to Androgen Receptors on Hair Follicles stimulates the production of excessive amounts of Sebum.
- Dihydrotestosterone potently stimulates the growth of Prostate Cancer cells (it is presently believed that
- DHT is five times more potent in stimulating Prostate Cancer cell growth than Testosterone). Sexual System
- Excessive serum Dihydrotestosterone is a principal cause of Enlarged Prostate.
Dihydrotestosterone Interferes with these Substances
- DHT inhibits the body’s production of Elastin.
These Substances Counteract Dihydrotestosterone
- Cosmeceuticals – Skin Improvers
- Ethocyn (applied topically) is claimed by its manufacturers to block receptors for Dihydrotestosterone.
- Estrogens are speculated to inhibit the production of Dihydrotestosterone.
- Progesterone inhibits the conversion of Testosterone to Dihydrotestosterone (DHT) (by inhibiting the activity of 5-Alpha Reductase, the enzyme that catalyzes the conversion of Testosterone to DHT).
- Enterodiol inhibits the binding of Dihydrotestosterone to Sex Hormone Binding Globulin (SHBG).
- Enterolactone inhibits the binding of Dihydrotestosterone to Sex Hormone Binding Globulin (SHBG).
- Matairesinol inhibits the binding of Dihydrotestosterone to Sex Hormone Binding Globulin (SHBG).
- Secoisolariciresinol inhibits the binding of Dihydrotestosterone to Sex Hormone Binding Globulin (SHBG).
- Beta-Sitosterol (60 – 130 mg per day) is strongly speculated to inhibit the conversion of Testosterone to
- Dihydrotestosterone by the 5-Alpha Reductase enzyme.
- Zinc inhibits the conversion of Testosterone to DHT (by inhibiting the activity of the 5-Alpha Reductase enzyme that is responsible for this conversion).
- Vitamin B2 inhibits the conversion of Testosterone to DHT by inhibiting the activity of 5-Alpha Reductase.
These Foods/Herbs Minimize the Toxic Effects of DihydrotestosteroneHerbs
- Nettle inhibits the binding of Dihydrotestosterone to Prostate cells (thereby preventing DHT from stimulating the proliferation of Prostate cells that leads to Enlarged Prostate and/or Prostate Cancer).
- Saw Palmetto effectively inhibits the production of Dihydrotestosterone and also blocks
- Dihydrotestosterone attaching at cellular binding sites, which increases its breakdown and excretion:
- Saw Palmetto lowers Dihydrotestosterone levels by up to 66% in the Prostate gland.
- Flax Seeds inhibit the binding of Dihydrotestosterone to Sex Hormone Binding Globulin (SHBG) (due to the Plant Lignans content of Flax Seeds).
These Substances Increase DHT Levels
- 5-Alpha Reductase catalyzes the conversion of Testosterone to DHT.
- Approximately 6 – 10% of the body’s free Testosterone is converted (via the 5-Alpha Reductase enzyme).
- Estrogens are a group of Female Sexual Steroid Hormones produced in the Ovaries and (to a lesser extent in males) the Testes. Estrogens raise HDL Cholesterol levels and lower LDL Cholesterol levels.
- Estrogens improve Blood Circulation to the Brain (and thereby alleviate Cerebral Insufficiency).
- Estrogens (preferably natural Estrogens identical in chemical structure to those produced endogenously) help to prevent Alzheimer’s Disease in post-menopausal women and improve the Mental Function of persons afflicted with Alzheimer’s Disease.
- Estrogens prevent Alzheimer’s Disease via numerous mechanisms.
- Estrogens improve Blood Circulation to the Frontal Lobe of the Brain.
- Estrogens normalize Brain Wave generation.
- Estrogens stimulate the production of and increase the Brain’s sensitivity to the effects of Nerve Growth Factor (NGF).
- Estradiol (one of the Estrogens) inhibits the ability of Amyloid-Beta Protein to destroy Neurons.
- Estrogens facilitate the growth of Dendrites.
- Estrogens are speculated to inhibit the deposition of Ceroid in the Brain.
- Estrogens improves Blood Circulation to the Frontal Lobe and Precentral Gyrus areas of the Brain.
- Estrogens improve Memory (studies have demonstrated the ability of Estrogen Replacement Therapy to improve Short-Term Memory and Long-Term Memory in women).
- Estrogens help to prepare the female body for Pregnancy.
- Estrogens are responsible for the growth and development of the Uterus at puberty.
Toxic Effects of Excessive Estrogens
The toxic effects of Estrogens only occur when the sum of Estradiol + Estrone exceeds 50% of the body’s total Estrogens . (i.e. when the proportion of Estriol is less than 50%).
Excessive Estrogens production increases the risk of some forms of Cancer:
- Estrogens potently stimulate Cell Growth in certain tissues. The more cells divide, the greater the risk that a genetic mishap will occur that could lead to the uncontrolled proliferation of Cells characterized by Cancer, especially:
- Breast Cancer (specifically 2-Hydroxyestrone form of Estrone)It is noteworthy that of the three types of Estrogens, Estradiol is 1,000 times more potent in terms of its ability to stimulate Breast tissue growth compared to Estriol.
- Pharmaceutical supplementation of Estrogens to postmenopausal females is a major cause of Endometrial Cancer (due to their Estrone and/or Estradiol component).
- Excessive endogenous production of Estrogens in women is implicated in Ovary Cancer.
- Excessive endogenous production of Estrogens in men is implicated in Prostate Cancer.
- The specific Cell growth that Estrogens are known to stimulate is Trophoblasts which are strongly implicated in Cancer when they are produced in situations other than Pregnancy.
Excessive use of exogenous, supplemental Estrogens by postmenopausal women increases their risk of developing Systemic Lupus Erythematosus (SLE).
Estrogens inhibit the mobilization of Adipose Tissue from Cellulite for redistribution to other areas of the body (possibly accounting for the greater incidence of Cellulite in females than in males).
- Excessive Estrogens levels can cause Depression (due to them blocking the Serotonin manufacturing properties of Vitamin B6).
- Excessive Estrogens levels or a high Estrogens:Progesterone ratio (Estrogens Dominance) may be a cause of Multiple Sclerosis.
- Elevated Estrogens levels or Estrogens activity is suspected of causing Endometriosis.
- Excessive production of Estrogens is implicated in the PMS-A (Anxiety) form of Pre-Menstrual Syndrome (PMS).
- Estrogens Dominance (i.e. an excess of Estrogens relative to Progesterone) is a common cause of Uterine Fibroids.
Controversial Aspects of Estrogen
It is widely believed that women require additional Estrogens (Estrogen Replacement Therapy) during and after Female Menopause:
During and following Menopause, a significant number of females do NOT require Estrogen Replacement Therapy – the female body still produces a small quantity of Estrogens (from Androstenedione within Adipose Tissue) – Estrogen production merely declines in tandem with the female body’s reduced requirement for Estrogens that were formerly necessary to prepare her Endometrium for Pregnancy.
Estrone is a type of Estrogen – it is a Female Sexual Steroid Hormone.
Potentially Toxic Effects of Estrone
- Excessive production of Estrone (and impaired conversion of Estrone to Estriol within the Liver) has been closely linked to Breast Cancer.
- Excessive endogenous production of Estrone can cause Endometrial Cancer.
- Excessive production of Estrone (and impaired conversion of Estrone to Estriol within the Liver) has been closely linked to Ovarian Cancer.
- Excessive production of Estrone increases the risk of Prostate Cancer.
- Excessive production of Estrone (and impaired conversion of Estrone to Estriol within the Liver) has been closely linked to Uterus Cancer.
Impaired conversion of Estrone to Estriol within the Liver causes the PMS-A form of Pre-Menstrual Syndrome (PMS).
These Factors Interfere with Estrone Production
Female Menopause causes a decline in female production of Estrone (and it is for this reason that post-menopausal women are often administered exogenous Synthetic Estrogens (this practice known as Estrogen Replacement Therapy (ERT))):
- Synthetic Estrogens differ in their chemical structure to that of the body’s natural Estrogens and can produce toxic side-effects that exceed those of natural, endogenous Estrogens. For this reason post-menopausal women are advised to consider the use of natural Estrogens in ERT (natural Estrogens are more difficult to procure than Synthetic Estrogens).
- The ideal proportion of Estrone (preferably natural Estrone) for post-menopausal females in Estrogens Replacement Therapy is:
– 3% Estrone combined with:
– 90% Estriol
– 7% Estradiol
Estradiol is the major (most biologically potent) Estrogen produced and secreted by the Graafian Follicle of the female Ovaries (and produced in smaller quantities in males) – note that Estradiol is not one single compound – there are two forms of Estradiol (of which Estradiol 17-Beta is the most biologically potent).
Estradiol helps to maintain normal Brain function and helps to prevent Alzheimer’s Disease in men (the main way that male Testosterone helps to maintain Brain function in men is through its conversion by Aromatase enzyme to Estradiol) – men have a higher concentration of Estradiol Receptors in their Brain than the concentration of Testosterone Receptors:
Male Alzheimer’s Disease patients have significantly lower levels of Estradiol than healthy control subjects.
Estradiol increases (female) Sexual Desire (by stimulating the endogenous production of Nitric Oxide Synthase (NOS) which catalyzes the production of Nitric Oxide (NO)).
Estradiol stimulates the growth of Cells of the Uterus.
Estradiol stimulates the growth of Cells of the Vagina.
(Atrophic) Vaginitis can occur as a result of insufficient endogenous production of Estradiol, especially in postmenopausal women – exogenous Estradiol (25 mcg per day administered locally to the Vagina via pessaries) alleviates Atrophic Vaginitis where the cause is insufficient endogenous production of Estradiol.
Estriol is a type of Estrogen – Female Sexual Steroid Hormone.
Health Benefits of Estriol
Estriol protects against carcinogen-induced, Estradiol and Estrone-induced, X-Rays-induced and Radiation Therapy-induced Breast Cancer:
Estriol competes with Estradiol and Estrone for the occupancy of Estrogens Receptors. Because Estriol has minimal ability to stimulate Cell proliferation, it thereby inhibits the ability of other Estrogens to stimulate Breast Cell proliferation (by occupying Estrogens Receptors that would otherwise be occupied by Estradiol or Estrone).
Estriol inhibits the ability of Estradiol and Estrone (and synthetic Estrogens that mimic Estradiol and Estrone) to stimulate the growth of Cancer Cells involved in Uterus Cancer.
Estriol (natural, not synthetic) is the primary natural Estrogen recommended for use in Estrogen Replacement Therapy (ERT) post-menopausal women whose production of Estriol declines significantly following Female Menopause. Intelligent physicians recommend that natural Estriol comprise 80% of the Estrogens in natural Estrogens Replacement Therapy. research
Estriol is produced endogenously in largest amounts by the Placenta during Pregnancy.
Estriol (Estriol cream applied intravaginally) alleviates many cases of Vaginal Atrophy.
Estriol (cream applied intra-vaginally) alleviates Vaginitis.
Estriol (specifically, topically applied 0.3% Estriol) retards and reverses some aspects of the Aging Process in the Skin:
- Topical Estriol increases the moisture content of the Skin.
- Topical Estriol markedly improves the elasticity and firmness of the Skin.
- Topical Estriol decreases Wrinkles (as measured scientifically by the depth of Wrinkles using Skin profilometry) by between 61% and 100%
- Topical Estriol decreases the size of Enlarged Pores (as measured scientifically Skin profilometry) by between 61% and 100%.
- Topical Estriol increases the quantity of Type III Collagen in the Skin and increase the quantity of Collagen Fibers in the Skin.
These Ailments Interfere with Estriol
Female Menopause causes a significant decline in the production of Estriol.
Melatonin is a Neurohormone (regarded as a Neuropeptide) produced by the Pineal Gland (and to a lesser extent in the Retina of the Eye and by the Enterochromaffin Cells of the Gastrointestinal Tract).
- Melatonin secretion declines rapidly in tandem with the Aging Process (see table).
- Melatonin possesses distinct Life Extension properties:
- Melatonin treated mice live for an average 20% longer than untreated mice. Photographs of “old” mice treated with Melatonin reveal that their fur is thick and lustrous and their bodies firm and streamlined, while the untreated mice have flabby bodies and wrinkled necks and scruffy coats that are graying in patches.
- Aspirin interferes with the endogenous production of Melatonin.
- Excessive consumption of Alcohol (ethanol) inhibits with the body’s production of Melatonin.
- Tobacco interferes with the endogenous production of Melatonin.
Progesterone is a type of female Sexual Steroid Hormone secreted by the Ovaries, Placenta and (in small amounts) by the Adrenal Cortex and (in males) the Testes.
Biological Function and Therapeutic Applications of Progesterone
- Progesterone inhibits the excessive proliferation of the Smooth Muscle of the Endothelium of Blood Vessels (excessive proliferation of the Smooth Muscle of the Endothelium of Blood Vessels can lead to Atherosclerosis).
- Progesterone helps to prevent many types of Cardiovascular Diseases (due to its ability to minimize risk factors for Cardiovascular Diseases such as elevated LDL Cholesterol, lowered HDL Cholesterol and elevated Triglycerides levels).
- Progesterone helps to prevent Heart Attack.
- Progesterone helps to prevent Hypertension (by facilitating the excretion of excessive Sodium from the body).
- Optimal endogenous Progesterone levels appear to assist the prevention of all forms of Cancer (in women) and some forms of Cancer (in men):
- Progesterone levels help to prevent the development of Breast Cancer.
- Progesterone helps to prevent Endometrial Cancer in postmenopausal females (by counteracting Estrogens-dominance that is implicated in Endometrial Cancer).
- Progesterone inhibits the growth of Prostate Cancer cells (by inhibiting the conversion of Testosterone to Dihydrotestosterone and by opposing the Prostate Cancer stimulating effects of Estrogens).
- Progesterone may stimulate Prostate Cancer cells to undergo Apoptosis (programmed cell death).
- Progesterone helps to prevent Uterus Cancer.
- Progesterone facilitates the utilization of Adipose Tissue in Energy production.
- Progesterone lowers total serum Cholesterol levels:
- Progesterone increases HDL Cholesterol levels.
- Progesterone lowers elevated LDL Cholesterol levels.
- Progesterone increases Energy levels – in its role as an uncoupling agent
- Progesterone facilitates the utilization of Adipose Tissue (body fat) in the production of Energy.
- Progesterone may be useful for the treatment of Obesity
- Progesterone facilitates the utilization of Adipose Tissue (body fat) for the production of Energy.
- Progesterone lowers elevated serum Triglycerides levels.
- Progesterone alleviates many cases of Fibromyalgia (according to many anecdotal reports).
- Progesterone deficiency is a major cause of Osteoporosis
- Progesterone increases bone mass density (BMD) by 7% after one year of supplementation, by 12% after two years, and by 15% after three years. Women administered supplemental Progesterone up to the age of 80 following Menopause exhibit strong Bones without evidence of Bone loss while continuing to use natural Progesterone.
- Progesterone is speculated to increase the chances of recovering from and surviving Coma.
- Progesterone improves Concentration ability in anovulatory premenopausal and postmenopausal women.
- Progesterone alleviates and helps to prevent some forms of Depression.
- Irritability can occur as a result of abnormally low Progesterone levels.
- Progesterone (cream applied topically) alleviates Migraine in many women
- Progesterone may be an effective therapy for Multiple Sclerosis (due to its ability to counteract estrogens dominance. research
- Progesterone facilitates the formation and maintenance of Myelin Sheaths. research
- Progesterone helps to restore normal Sleep cycles.
- Progesterone helps to prevent Miscarriage:
- Progesterone prevents the premature shedding of the supportive secretory Endometrium during Pregnancy.
- Progesterone alleviates Ovarian Cysts.
- Progesterone increases female Sexual Desire.
- Progesterone (cream applied topically) alleviates Uterine Fibroids (by counteracting the estrogens dominance that is the underlying cause of many cases of Uterine Fibroids).
- Progesterone (Progesterone cream applied intravaginally) alleviates many cases of Vaginal Atrophy.
- Natural, exogenous Progesterone (cream applied topically) alleviates Vaginitis (including the vaginal dryness and atrophy of Mucous Membranes of the Vagina that are associated with Vaginitis).
- Progesterone (cream applied topically) alleviates many cases of Acne in adult women (by counteracting the excessive production of Androgens that causes most cases of adult Acne in women).
- Progesterone (as a component of some Cosmeceutical Skin Moisturizers) alleviates Dry Skin (by facilitating the retention of Water in the Skin).
- Progesterone (cream applied topically) alleviates many cases of Psoriasis.
- Progesterone (cream applied topically) alleviates many cases of Rosacea in women.
- Progesterone (cream applied topically) alleviates many cases of Seborrhea in women.
- Progesterone (cream applied topically) helps to remove fine Wrinkles from aged Skin.
- Testosterone is the principal Androgen (Male Sexual Steroid Hormone).
- Testosterone increases the body’s Basal Metabolic Rate (BMR).
- Abnormally large Breasts can occur in women as a result of insufficient endogenous production of Testosterone.
- Testosterone alleviates Male Impotence.
- Supplemental, exogenous, natural Testosterone often alleviates Male Menopause (by counteracting the decreased free serum Testosterone associated with increased levels of Sex Hormone Binding Globulin). Testosterone is responsible for (and increases) Sexual Desire (libido) in both males and females:
- Lack of Sexual Desire (libido) in post-menopausal females is often caused by insufficient Testosterone production – supplemental Testosterone (administered by a qualified practitioner implanting a Testosterone “pellet” under the skin every six months) often restores the libido of such females.
- Testosterone exerts its effects on Sexual Desire by influencing (presently unidentified) Receptors in the Brain.
- Even small surges in Blood “free” Testosterone levels can increase Sexual Desire.
- Testosterone is responsible for stimulating the development of Male Sexual Organs and male secondary sexual characteristics (e.g. beard growth, deepening of the voice) during puberty.
- Testosterone improves (male) Sexual Performance (men with low serum Testosterone levels (i.e. below 1.4 ng/ml) exhibit impairment in Sexual Performance (as measured by night erections)).
- Testosterone (cream applied topically to the Clitoris) improves (female) Sexual Performance (by increasing the sensitivity of the Clitoris).
- Testosterone regulates the production of Sperm in males.
- Testosterone is responsible for stimulating the development of female secondary sexual Hair.
These Substances Facilitate the Production/Function of Testosterone
Acetyl-L-Carnitine (ALC) increases plasma Testosterone levels (via its influence on Acetylcholine neurotransmission in the Striatal Cortex of the Brain).
These Substances Interfere with Testosterone
- Caffeine decreases free Testosterone levels (in postmenopausal women).
- Elevated Cortisol levels inhibit the production of Testosterone.
- Melatonin inhibits the production of Testosterone – although low dosage levels of Melatonin (up to 3 mg per day) do not appear to interfere with Testosterone production.
- Progesterone lowers endogenous Testosterone production (in men) to levels that prevent the proper maturation of Sperm.
- Alcohol (ethanol) decreases the production of Testosterone and lowers the body’s Testosterone levels.
- Cocaine lowers serum Testosterone levels. Marijuana reduces serum Testosterone levels.
- Tobacco smoking inhibits the production of Testosterone (by causing the destruction of Leydig Cells that normally produce Testosterone).
- Vegetarians have approximately 18% lower Testosterone levels compared to meat eaters (this occurs because vegetarians have a lower intake of Dietary Fats which are precursors for Testosterone production; also the Fiber Polysaccharides in Vegetables bind to Testosterone and other Steroid Hormones).
- Excessive Exercise (i.e. overtraining) suppresses the body’s Testosterone production:
- Endurance Exercise reduces (both bound and free) Testosterone levels.
- Excessive Isotonic Exercise (i.e. overtraining) can cause (temporary) depletion of endogenous Testosterone during the 24 – 48 hour recovery period between workouts in people who engage in Isotonic Exercise.