Controlled vocabulary supplemented with keywords was used to search for studies according to each defined question. Should I consult a doctor before starting an exercise program for testosterone enhancement? Can overtraining negate the testosterone-boosting effects of exercise? Is there an ideal age to start exercising for testosterone benefits? If you suspect you have low testosterone, consult with a healthcare professional. Symptoms of low testosterone can include fatigue, decreased libido, erectile dysfunction, loss of muscle mass, increased body fat, and mood changes.
The differences in testosterone methodologies have led to considerable effort by a variety of parties including the Centers for Disease Control (CDC) and the College of American Pathologists towards harmonization of assays. It is bound to albumin (50%, loosely-bound), sex hormone-binding globulin (SHBG, 44%, tightly-bound), corticotropin-binding globulin (4%, loosely-bound), and approximately 2% circulates as free testosterone.9 The free and loosely-bound testosterone fractions combined are known as bioavailable testosterone.Testosterone assays are plagued by variability in results. Early morning samples from each subject's most recent and previous 3 visits as well as those from 10, 15, 20, 25, and 30 years prior were analyzed (3,565 samples total with a mean of 4 samples per patient). Finally, testosterone pellets are also available in branded form, with no generic agents currently available. While all products contain the same medication (testosterone), each product and modality has distinct pharmacokinetic and application attributes based on the excipient agents and the permeator components.
Dose adjustment, based on a 2-hour post-application testosterone measurement, was utilized to maintain serum testosterone concentrations within the adult male range.42 In the sub study, ambulatory 2-hour post-application testosterone concentrations were measured in random order at two ambulatory clinic visits and during a 24-hour in clinic pharmacokinetics study. It should be noted that substantial day to day variations of serum testosterone concentration is often seen in the same man as well as among different men after testosterone gel application. One reason for this reservation for their use in treating hypogonadal adult men is that they are not aromatizable and may result in greater increase in LDL cholesterol and decrease in HDL cholesterol levels.26 In addition, the 17 alpha-alkylated androgenic steroids (methyltestosterone, oxymetholone, and stanozolol) are hepatotoxic, whereas testosterone, testosterone esters and 19-nortestosterone showed no toxic effects on the liver.27-30 Thus these modified 17 alpha-alkylated androgens are not recommended for testosterone replacement therapy.
The mechanisms by which physical activity influences testosterone production are complex and multifaceted. The authors would like to graciously thank Joseph Kanasz, BFA, from the Cleveland Clinic Center for Medical Arts and Photography for creation of Figures 1-2 in this manuscript. The decision on the best product choice should include patient preference, PKs, treatment burden, cost and insurance coverage.
As oral TU capsules are recommended to be taken with a meal, serum T levels appear to be modulated by dietary fat content.88Cavg and mean Cmax serum T levels were approximately 2‐fold higher when 200 mg oral TU was administered with food compared with fasting.87 Dietary fat was found to affect mean serum T levels achieved with oral TU; meals with higher fat content increased serum T concentrations. Historically, oral TTh with non‐esterified T has been unsuccessful in delivering physiological T because of first‐pass hepatic metabolism; to overcome this, high doses were needed to achieve measurable serum T levels.86 A new, oral TU formulation delivered via a self‐emulsifying drug delivery system was developed to promote solubilization and absorption of the lipophilic TU in the gastrointestinal tract, and in March 2019, became the first oral TTh approved by the FDA. With the 60 mg/day dose, mean TT concentrations were 15.8 nmol/L (456 ng/dl) and 17.6 nmol/L (508 ng/dl) on days 15 and 120, respectively; peak T levels were reached at 2 h post‐application, and T peak‐to‐trough ratios were maintained around 3 from day 15 to 120. Of the 155 enrolled men, 135 men completed the 120‐day study.76 On day 15, 76.1% of patients had Cavg within the pre‐defined normal range (10.4–36.4 nmol/L, or 300–1050 ng/dl), which increased to 84.1% by day 120. The PK and clinical profile of TESTIM®/VOGELXO® 1% gel were evaluated in men with TD against other TTh in various studies.71, 72, 73 There were 3 concentration maxima observed with both TESTIM®/VOGELXO® 1% and AndroGel® 1%; peak T levels were reached at 3 to 4 h, 8 to 10 h, and 18 to 24 h post‐application. Steady‐state serum T levels were achieved within a few days, and these levels were maintained with once‐daily applications. In 34 men from a multicenter, phase 3 study of a transdermal T patch system for TD, nightly applications of 2 patches (5.0 mg/day) resulted in peak levels occurring in the morning after application and decreasing slowly until system removal, mimicking the circadian patterns reported in healthy, young men.52