Does Testosterone Matter For Strength & Muscle? - Shocking Answers From Leading Scientists

Will a post-workout hormone response of testosterone, GH, and IGF-1 make you bigger and stronger?

The widely accepted belief is that they will. Recent research shows this may not be so.

Although we do know that these hormones build muscle and tissue in specific situations, such as when large supplemental doses of testosterone are taken in conjunction with resistance training, the evidence is not conclusive that the natural post-workout hormone response has much effect on muscle development.

Unfortunately, we don’t have conclusive answers yet. Recent studies that used different research designs show conflicting outcomes. A study from Norway showed that by raising blood hormone levels by training a high volume of legs prior to arms, it’s possible grow muscle and gain strength to a greater degree than if the hormones are at resting levels.

This study had young men train either a large volume of leg exercise to have high levels of testosterone, GH, and IGF-1 circulating when they trained unilateral biceps curls at the end of the workout. This led to significantly greater 1RM strength and growth in the cross-sectional area of the elbow flexors than when the trainees did biceps curls alone with no leg exercises (a condition that resulted in no increase in circulating hormones).

These results appear to support the existing idea that elevating the anabolic hormones is important and will lead to superior gains. However, the study design was criticized by other scientists because training loads for the biceps were not different between the conditions, but oddly, the final 1RMs were. Typically, trainees will progress to higher training loads if they are developing more strength, but that’s not what happened in this study.

In addition, the increase in muscle CSA only occurred at two out of the four measured sites—an outcome that is not altogether unheard of since muscle fibers do tend to grow in a non-uniform fashion.

Scientists from McMaster University in Canada disagree with the outcome of the Norwegian study and are convinced the hormone-response to training has no effect on protein synthesis, strength, or hypertrophy. Their studies have convincingly shown that muscles grow to a similar degree whether the “anabolic” hormones are present or not.

“Hypertrophy happens in the absence of that response,” writes Dr. Stuart Phillips in an in email interview. Phillips is one of the leading scientists from McMaster who has been investigating the issue.

He provides the following suggestion for coaches who aren’t worried about specific mechanisms that drive muscle building and just want to know how to get their athletes bigger and stronger.

“Don’t bother measuring hormones or worrying about them as they do basically nothing—it’s just an acute stress response. They change to such a small extent and for such a short time, they don't exert any physiological effect.”

A closer look at how Phillips and the McMaster research lab came to this conclusion shows the following:

• Phillips writes that he got tired of listening to people talk about the theory that the exercise-induced hormone response influences hypertrophy with little-to-no evidence. When Dr. Daniel West entered the McMaster program a few years ago, he and Phillips got together to test the theory out.
• First, the McMaster lab designed the following training protocol, which they used for two studies (the first for a single workout, and the second for a long-term 15-week study):

They had active young men train a Low Hormone condition and a High Hormone condition. In the Low Hormone condition they did unilateral biceps curls only. In the High Hormone condition they trained the contralateral arm with the same biceps curls followed immediately by a bout of 11 sets of leg exercises.

The High Hormone condition significantly elevated testosterone, GH, and IGF-1. The Low Hormone condition did not.

• Results after the single workout showed that protein synthesis was elevated by 78 percent following the Low Hormone trial compared to only 61 percent following the High Hormone trial. It was concluded that post-workout hormone response doesn’t enhance anabolic signaling or protein synthesis.
• Then, they had the subjects perform the Low Hormone and High Hormone workouts twice a week for 15 weeks to see if there was any difference in muscle or strength development in the biceps.
• Results showed that there were NO differences in 1RM elbow flexion strength, isometric strength, or muscle fiber cross-sectional area between the two groups.

The research group suggests that instead of designing training programs based on nuances in hormone response, they need to be designed to maximize protein synthesis through muscle fiber loading and nutrition.

Dr. Phillips and his researchers are very outspoken that the exercise physiology community went wrong in accepting the idea that the “anabolic” hormone response to training builds muscle.

How did this happen?

“It was accepted without any data! People just looked at the increase in T, GH, and IGF-1 and said ‘Hey they're 'growth hormones' that's how hypertrophy works!’ without every looking to actually test the hypothesis,” writes Phillips.

He says that his lab will continue to generate data to refute the thesis—they just came out with a large study that showed a weak correlation between cortisol, GH and muscle fiber cross-sectional area, with no relationship between testosterone and hypertrophy or strength.

“It seemingly takes more than the 5 to 6 well-designed studies we've done to convince those who ‘believe’ (it's almost a religious construct because in the absence of actual data you have to believe) that a rise in hormones that last about 15 to 30 minutes could exert a meaningful effect.”

Phillips explains that people often point to the “steroids argument" that enormous doses of supplementary testosterone increases muscle and strength. “That's a completely different paradigm and people who use that as an argument need a lesson in circular logic and deductive reasoning!” he writes.

Of course, it all comes down to identifying what works so we can get leaner, stronger, bigger, and perform better athletically. Here are a few take away points from Drs. Phillips and West:

• To drive hypertrophy in the short term, the key is to maximize protein synthesis. A threshold volume of training is critical to enhance protein synthesis pathways. For example, research shows that activation of certain muscle building pathways (called p70s6K1) are rejuvenated by taking protein 24 hours after training, particularly if a greater volume (at least three sets to failure) is performed.
• Post-exercise nutrition in the form of protein ingestion is critical and can markedly increase the protein synthesis response. Milk protein is superior to soy or carbs. Evidence from other scientists shows whey, which is derived from milk, is the best protein source of all.
• In speculating on the significance of the hormone response to resistance training, Dr. West suggests it could be to help mobilize fuel sources to meet the energy demands of the exercise. It’s also possible exercise-induced hormones like GH and IGF-1 help to remodel connective tissues, which could be relevant for maximal strength, since stronger connective tissue could enhance the ability to endure higher training loads.
• Measuring testosterone (T) can be useful in order to assess training motivation and readiness to perform or compete. This was not addressed by the McMaster research group, but scientists from Imperial College in London found that T levels are relevant for athletes with high levels of baseline strength.

For example, one study showed that in male athletes with high strength levels (1RM squat of 2 times body weight), free T was a strong individual predictor of squat and sprinting performance. For weaker athletes (1RM squat of less than 1.9 times body weight), free T was a poor predictor of performance.

• A variety of studies have shown that athletes with higher T levels before training or competition will perform better and are more likely to win. This holds true for men and women: A recent study of pre-workout T levels in elite netball players showed that T was positivity correlated with self-selected squat and bench press workload and maximal medicine ball throw performance.
• Light load training to failure has been shown to trigger a similar degree of hypertrophy as heavy load training in untrained individuals. This shows that lighter loads with adequate volume can be used to build or maintain muscle mass in the general population, and it’s particularly relevant for older people.
• For athletes, a high degree of maximal strength is clearly advantageous. For advanced trainees, heavier loads appear to be superior because they result in greater neuromuscular adaptations.