Pre-workout (PWO) supplements are multi-ingredient dietary formulas intended to be taken before exercise to enhance immediate physical performance, boosting energy, focus, strength, and endurance. Testosterone is the primary male sex hormone, playing a major role in muscle protein synthesis, bone density, and overall metabolic health. The core question for many users is whether consuming a standard PWO blend can directly increase their body’s natural testosterone levels.
Primary Functions of Standard Pre-Workout Ingredients
The intended purpose of most pre-workout formulas is to improve acute training capacity, not to alter long-term hormone profiles. The most common ingredients function as metabolic and neurological aids that sharpen the mind and body for the immediate task of exercise. Caffeine serves as the central nervous system stimulant, blocking the effects of adenosine to increase alertness, focus, and perceived energy levels. This neurological effect helps to decrease the perception of effort, allowing users to push harder for longer periods.
L-Citrulline and dietary nitrates, often sourced from beetroot, are included primarily to boost nitric oxide production. Nitric oxide signals blood vessels to relax and widen, a process known as vasodilation. This improved blood flow allows for more efficient delivery of oxygen and nutrients to working muscles, enhancing the temporary muscle fullness known as “the pump” and supporting endurance.
Beta-Alanine is a non-essential amino acid that works by increasing muscle carnosine concentrations. Carnosine acts as a buffer against the accumulation of hydrogen ions, which cause the drop in muscle pH that leads to fatigue during high-intensity exercise. By buffering this acidity, Beta-Alanine helps delay the onset of muscle fatigue and enhances high-intensity exercise capacity.
Analyzing the Direct Hormonal Effects of Common Compounds
The ingredients commonly found in PWO, such as caffeine and creatine, are not classified as direct testosterone boosters, though they can have secondary hormonal effects. Creatine, one of the most studied supplements, is widely recognized for its ability to increase muscle mass and strength. Research indicates that creatine supplementation does not consistently raise total testosterone levels in healthy individuals.
However, some studies, notably a 2009 trial involving male rugby players, observed that a creatine loading phase significantly increased levels of Dihydrotestosterone (DHT). DHT is a more potent androgen derived from testosterone. Other research has found no significant changes in DHT, total testosterone, or free testosterone following creatine use, suggesting the hormonal impact may not be universal or sustained.
Acute, high-dose caffeine intake can sometimes cause a transient increase in testosterone levels, particularly when paired with resistance exercise. For example, one study using a high dose of 800 mg of caffeine found a 21% increase in testosterone concentration. However, this same high dosage also produced a 52% increase in cortisol, a stress hormone that works against the anabolic effects of testosterone. This simultaneous rise in cortisol often results in a decline in the testosterone-to-cortisol ratio, which can counteract any potential anabolic benefit from the temporary testosterone spike.
Identifying Dedicated Testosterone-Boosting Additives
Some PWO formulas are marketed as “hybrid” supplements because they include ingredients specifically intended to support hormonal balance, which are not standard performance enhancers. Consumers seeking a hormonal effect must actively look for these compounds on the product label. D-Aspartic Acid (DAA) is one such ingredient, and its proposed mechanism involves stimulating the release of luteinizing hormone, which signals the testes to produce more testosterone.
While DAA has shown promising results in animal models and in untrained men with lower baseline testosterone, studies on resistance-trained men have yielded inconsistent results. Some human trials have shown no significant effect on testosterone or body composition. One study even found a decrease in testosterone at a high dose of six grams per day.
Fenugreek extract, another common additive, contains furostanolic saponins that may inhibit the enzymes responsible for breaking down testosterone, potentially increasing free testosterone levels. Tribulus Terrestris is also sometimes included, based on the belief that its steroidal saponins can stimulate luteinizing hormone. However, the majority of high-quality human studies do not support the claim that Tribulus Terrestris significantly or consistently increases total testosterone levels. These dedicated compounds are distinct from the primary PWO ingredients, although their efficacy in healthy, trained individuals is highly variable and often minimal.