Like Viagra, Cialis also is used to treat erectile dysfunction. What’s the difference between the two? Although Viagra and Cialis both work by inhibiting an enzyme called phosphodiesterases, which increases vasodilatation, there are pharmacologic distinctions between Viagra and Cialis, being that Cialis has a longer half-life (17.50 hours) compared to Viagra (4.0–5.0 hours) and Levitra (4.0–5.0 hours), resulting in longer duration of action14 which is partly responsible for Cialis being dubbed "The Weekend Pill." Cialis’ molecular structure differs significantly from Viagra; one of the benefits of Cialis is there are no visual side effects like Viagra and an absence of effect of food on absorption. Nitric oxide is a hot topic of debate in bodybuilding, as NO-producing supplements are always one of the top-selling products. Being in touch with many bodybuilders and powerlifters, many swear that by taking Cialis, they get better pumps in the gym and can recuperate from exercise faster.
Many suspect its enhanced nutrient delivery or some other mechanism. Cialis demonstrates similar vasodilator (blood pressure-lowering) effects in healthy subjects when compared with Viagra in studies of 10mg or 20mg doses (mean systolic blood pressure reduction, of ~4.3mg). Many of the experts in sports will attest that nitric oxide only increases performance in environments with low oxygen availability, such as high-altitude training or areas with high air pollution. If there are no performace-enhacing effects, then why were Olympic athltetes using it? There have only been a handful of studies on the performance-enhancing effects of Cialis and sports performance, and none yielded beneficial effects.
- In one study, 14 healthy young males were given a 20mg dose of Cialis or a placebo and performed a maximal exercise test on a treadmill. The study found that a single dose of Cialis had no effect on exercise performance, exercise tolerance or cardiopulmonary responses.
- The second study involved three “all-out” sprints to determine if Cialis could increase anaerobic threshold. The study found no significant differences in peak power, average power or fatigue index compared to a placebo. One positive finding noted was that Cialis decreased the time to reach peak power. Cialis did not have an effect on peak power, but time to peak power output was reduced. Only to sports that need to reach maximum power output in a few seconds could Cialis administration be beneficial.
Bodybuilders are known for bringing cutting-edge pharmacology to the forefront of science. If NO (nitric oxide) products really don’t work, then why do so many people use them? Given that the second study reported that the author claimed that Cialis may increase peak force, the powerlifters who swear by Cialis increasing performance may be onto something that research has not discovered yet.
Based on the research, acute dosages of Cialis do not have performance-enhancing effects, but new research suggests that Cialis increases testosterone! Researchers had participants perform three 30-second “all-out” sprints to exhaustion and measured testosterone and cortisol responses to exercise. They found that only after Cialis and exercise did testosterone increase, however Cialis also increased cortisol levels. Cialis also lowered the DHEA to cortisol response. The study demonstrates that Cialis increases the “stress” response to the body, but also has some testosterone-enhancing effects as well. It’s interesting that a large dosage of caffeine, which is a weak, non-specific PDE inhibitor, also caused an increase in testosterone and also an increase in cortisol. So it seems that Cialis has both positive and negative effects on muscle. Cialis does not directly stimulate testosterone secretion per se, meaning it does not stimulate LH release or SHBG release directly. This is not the first study to find that Cialis raises testosterone:
- In a study of 74 patients with erectile dysfunction treated on demand with 50mg of Viagra or 20mg of Cialis for three months, basal levels of total testosterone and free testosterone were at the bottom of the normal range that was reversed after treatment in both groups. Testosterone increase in Viagra-treated cases was significantly lower than in those treated with Cialis, suggested to be due to the higher frequency of full sexual intercourse in the Cialis-treated group.
- Another study reported that the increase in testosterone from taking Cialis is mediated by a reduction in estrogen demonstration that Cialis may have anti-estrogen actions. It was pointed out that the T/estradiol ratio was associated with long-term Cialis treatment. There was no increase in LH levels from Cialis, demonstrating that Cialis did not directly increase testosterone, but indirectly increased testosterone by lowering estrogen.
- One of the primary reasons that many older men have problems “rising to the occasion” is that they have excess estrogen levels. Furthermore, in men with hypogonadism, a low dose of clomiphene citrate (Clomid) is effective in improving testosterone:estrogen ratio, thus giving more long-term benefit for the management of erectile dysfunction in hypogonadal patients. It seems that based on the current study, Cialis has similar actions to Clomid by improving T:E ratio.
