Squat vs. Leg Press: Effects on Testosterone, Growth Hormone and Cortisol

(Originally posted on 22-04-2014) WhetherSquat vs leg press training with free weights is more effective than training on machines has been an ongoing debate and both methods have their advantages and disadvantages. To see which has the largest effects on our hormones scientists of the University of North Texas started a study on the effects of two of the most popular leg exercises: the squat vs leg press.

What did the researchers do?

The reseachers recruted 10 healthy young men with at least six months resistance training experience. Their 1 repetition maximum (1RM) on both the squat and the leg press was measured in two different sessions with a week in between. One and two weeks after determining the 1RM for both exercises they performed either a squat and a leg press training respectively. The training consisted of six series of 10 repetitions seperated by two minutes of rest. The weight the subjects trained with was set at 80% of their 1RM on the respective exercise. The weight was decreased when subjects were unable to complete 10 repetitions. Before training, directly after and 15 and 30 minutes after training blood samples were taken from the subjects and analysed on TestosteroneGrowth hormone and Cortisol concentrations.

What were the results?

The results are depicted in the figures below:

Squat vs leg press Testosterone

Figure 1: Effects on Testosterone concentration in nmol per liter.

 

 

 

 

 

 

 

 

 

 

 

 

Squat vs leg press growth hormone concentrations

Figure 2: Effects on Growth Hormone concentration in μgram per liter.

 

 

 

 

 

 

 

 

 

 

 

 

Squat vs leg press cortisol concentrations

Figure 3: Effects on Cortisol concentration in nmol per liter.

 

The results of this study indicate that both the Leg Press and the Squat increase testosterone, growth hormone and cortisol concentrations at all measured times in comparison with the pre training concentrations. However, testosterone concentration directly after training was 16.7% higher after the squat exercise. Growth hormone concentration increased even more at all times compared with the leg press (239.3% 156.3% and 122.2% higher in comparison with the leg press directly after training, 15 minutes after training and 30 minutes after training respectively). Lastly both the leg press and the squat significantly increased cortisol concentrations similarly.

What did the researchers conclude?

Based on the results described above the researchers concluded that the squat stimulated testosterone and growth hormone production to a larger extend than the leg press. The muscle breakdown stimulating hormone cortisol was increased similarly in both exercises. These results imply that the squat exercise is a more effective exercise to stimulate muscle growth than the leg press. This is caused by the larger increases in muscle building hormones testosterone and growth hormone and a similar effect on cortisol. The differences in hormonal reactions are likely to be caused by a difference in total work. The subjects were able to move more weight on average in the squat training session than in the leg press session. In addition the squat requires more muscle groups to be activated because of higher stability demands during the exercise. Or in other words, more muscles are required to stabilize the movement and prevent falling over.

What does this mean for me?

-The squat is a more effective exercise than the leg press to help the leg muscles grow.

See also:

-Free weights vs machines

Reference:

-Shaner, A.A., Vingren, J.L., Hatfield, D.L. et al. The acute hormonal response to free weight and machine weight resistance exercise. Journal of Strength & Conditioning Research 2014, 28, 4, 1032–1040.