The Myth About Squats, Testosterone and Muscle Growth

You’ve probably come across the claim that certain exercises, most notably squats and deadlifts, increase your testosterone levels, which in turn will lead to a faster rate of muscle growth.

Google around, and you’ll see headlines like:

• Exercises That Increase Testosterone Levels
• The Best Exercises to Increase Testosterone
• 7 Best Exercises to Naturally Increase Testosterone in Men
• 5 Moves to Boost Testosterone
• 10 Testosterone-Boosting Workouts

The idea is that this exercise or that workout will increase testosterone levels naturally, putting you on the fast track to bigger, stronger muscles. I’ve even come across claims that certain workouts “can help men increase T levels naturally without the need for expensive hormone replacement therapy.”

It would be great if it were true, but it isn’t.

In fact, the size and duration of any post-exercise increase in testosterone is too small and too short-lived to have any meaningful impact on muscle growth.

Here’s a closer look at what the research has to say on the subject of squats, testosterone and muscle growth.

Squats, Testosterone and Muscle Growth

Squats have been shown to increase testosterone levels after exercise [1]. In fact, squats or no squats, training sessions that involve large amounts of muscle mass and relatively heavy weights typically lead to an increase in testosterone [3].

Back in the 1990’s, researchers from the US Army Research Institute of Environmental Medicine rounded up a group of men, and put them through multiple workouts involving eight exercises – the leg press, leg extension, military press, sit-ups, arm curls, bench press, seated row and lat pulldown [2]. 

Blood samples taken 5, 15, 30, 60, 90, and 120 minutes after training show a significant increase in testosterone levels.

And it’s not just testosterone. There was also a spike in both growth hormone and IGF-1, two hormones that often are labelled “anabolic.”

This line of research offered some support for ideas that have been popular for decades, such as “to get big arms, you need to train your legs” or “deadlifts and squats make your whole body grow.”

Deadlifts and Squats Increase Testosterone, But Does it Matter?

We’ve known for some time that any temporary surge in post-training hormone levels is too small to have any impact on muscle protein synthesis [4], muscle fiber hypertrophy [5] or strength gains [6].

Post-exercise changes in testosterone levels also fail to explain why some people build muscle faster than others, even when they eat and train the same.

A study published in the European Journal of Applied Physiology analyzed data collected from a group of men who took part in a three-month resistance training program [7].

If the post-exercise change in testosterone levels was important as far as muscle growth is concerned, you’d expect to see two things: 

Guys with the largest testosterone response to training would build the most muscle. And those with the smallest response would build the least muscle. 

But when they looked at the data, the researchers could find no significant link between the exercise-induced rise in testosterone levels and gains in muscle mass. 

The hormonal responses of those who made the fastest gains in size and strength were no different than those who made the slowest gains.

In fact, the amount of testosterone you have at rest — in healthy young men, at least — doesn’t appear to have much of an impact on your gains either. 

In one study, guys who built the most muscle after several months of resistance training weren’t the ones with the highest testosterone levels, but the ones with more androgen receptors [8].

Androgen receptors respond to a hormone like testosterone by signaling muscle cells to increase the rate at which new muscle protein is laid down. Over a period of weeks and months, the increase in muscle protein synthesis will generate bigger, stronger muscles.

Guys who saw the biggest gains in muscle size didn’t have higher testosterone levels, but they did have more androgen receptors in their muscles. This meant their bodies could make better use of the testosterone that was available.

Why Training Legs Won’t Make Your Arms Grow

Some trainers also think that working small muscle groups, such as the biceps and triceps (which don’t elevate hormone levels when trained on their own), alongside larger muscle groups will make your arms grow more quickly. 

For example, you might do squats or deadlifts before training your arms in the hope that any subsequent increase in testosterone will accelerate growth in your biceps and triceps.

However, most research shows that doing so isn’t going to make your arms grow any faster.

A team of scientists from New Zealand got two groups of men to train their biceps twice a week for 10 weeks [9]. The first group trained the biceps alone, while group two did the same exercises as part of a full-body workout.

The size of the biceps increased in both groups. But there was no significant difference in gains between the biceps-only and the biceps + full-body workout groups.

A similar trial looked at muscle growth in a group of men who trained their biceps for 15 weeks on separate days and under different hormonal conditions [10].

In the low hormone condition, subjects trained the biceps on one side of their body. On a separate day, they did the same exercise for the other arm, which was followed immediately by several leg exercises designed to boost levels of growth hormone, testosterone and IGF-1.

In essence, the researchers were able to manipulate hormone levels so that, during the post-exercise period, one arm was repeatedly exposed to marked increases in testosterone, GH, and IGF-1 levels. The other arm was exposed to much lower levels of these hormones.

Because one arm of the subjects served as a control, both conditions also had the same genetic environment.

If the hormonal response to exercise was as important as some say it is, you’d expect to see the arm that was trained along with the legs and exposed to higher hormone levels grow more quickly.

But that isn’t what happened.

The size of the biceps increased to a similar extent in both groups — 12% in the low hormone condition versus 10% in the high hormone condition.

Strength also increased in both arms, but the increase was not different between the low hormone and high hormone conditions.

To quote the researchers directly:

“These findings, combined with our previous work, provide multiple lines of evidence that exercise-induced elevations of purportedly anabolic hormones are not necessary for, and do not enhance, muscle anabolism in young men. Our data indicate that exercise-induced changes in concentrations of systemic hormones do not reflect the underlying processes of muscle protein accretion and cannot be used as a proxy marker of muscle hypertrophy.”

Final Thoughts

Bottom line? Compound lifts like deadlifts and squats do lead to a short-term increase in various hormones, including testosterone, growth hormone and IGF-1.

However, this temporary surge doesn’t do much for muscle growth, and designing a training program to maximize post-exercise hormone levels is unlikely to have much of an impact on the speed at which muscle is gained.