The purpose of this article is to establish safe and effective methods or modalities for naturally boosting testosterone production. The modalities I’ll discuss largely effect testosterone in males, but may work to increase testosterone in females to a lesser degree.3, 5 Females have approximately 10 to 30 times less testosterone than males. Therefore, anabolic actions in females rely more on other anabolic hormones such as growth hormone and IGF-1.3, 5, 6 The same principles used in this article may help naturally increase testosterone in those with normal levels or low levels for their respective gender. Be aware, however, that there is no natural modality (exercise or otherwise) that will raise levels above the upper limit of normal for any of the anabolic hormones. It is also important to note that individuals with clinically low levels of testosterone should consult with a physician regarding medical treatment.

There are four main hormones responsible for the anabolic processes necessary for tissue repair and recovery: testosterone, human growth hormone (HGH), insulin, and insulin-like growth factor-1 (IGF-1). The mechanisms for the anabolic action of testosterone include increased protein synthesis, stimulating the release of growth hormone (which then causes the liver to produce IGF-1), and increased production of neurotransmitters. Any athlete looking to increase recovery and maximize gains in strength, power, or overall output would benefit from optimizing levels of testosterone.

High intensity resistance training and strength training can increase both free and total testosterone during and after exercise, as well as increase the resting concentration of serum testosterone.3, 5, 6 In addition to increasing free and total testosterone, resistance training has been shown to increase androgen receptors (the receptors that bind to testosterone) in the muscle.3, 5 In fact, just one to two resistance exercise sessions can increase androgen receptors.1 If more receptors are available, there is a greater capacity to bind more testosterone, therefore enhancing the anabolic effects.

There are a number of exercise variables that affect increases in serum testosterone levels. The variables include: large muscle group exercises or multi-joint exercises, heavy resistance, moderate to high volume and intensity of exercise, short rest intervals, two years or more of resistance training experience, and workouts of no longer than 60 minutes. To optimize testosterone increases, utilizing a combination of the above variables is recommended.

Large Muscle Group Exercises
1, 2, 5, 7

Large muscle group exercises or multi-joint movements stimulate a larger percentage of muscle fibers. There is a direct correlation with the amount of muscle fibers stimulated and the hormonal response. In fact, only the muscle fibers stimulated through exercise exhibit binding of testosterone at the muscle androgen receptors. Some of the best examples of multi-joint movements are Olympic lifts, deadlifts, and squats. There are numerous muscle groups involved in these multi-joint exercises. Research has shown that even performing larger muscle group exercises prior to smaller muscle groups creates a significant increase in testosterone that the smaller muscle groups may benefit from. This may indicate an order of exercise (larger muscles first) to maximize testosterone response and utilization. 9

Heavy Resistance.
1, 2, 7

Heavy resistance is usually defined by approximately 85-95 percent of your 1RM. The heavier resistance loads the muscles, causing an increase in the recruitment of muscle fibers. As stated earlier, the more fibers stimulated, the greater the hormonal response. The use of lighter loads or resistance, even with high repetitions, does not provide enough of a stimulus to significantly increase the percentage of muscle fibers needed for an increased hormonal response. Smaller motor units and slow twitch muscle fibers are usually recruited first. As the load increases, larger motor units and fast twitch fibers become involved. If you’re interested in muscle growth, this is important, because fast twitch fibers display a greater capacity for hypertrophy than slow twitch fibers, and they will only respond if they are stimulated.

Volume and Intensity of Exercise
1, 2, 5, 7

There must be a significant volume and intensity of exercise. This can include the number of sets, number of exercises, and frequency of exercise. Without sufficient volume, there will not be any significant increase in testosterone.14 Low intensity and low frequency of exercise will also produce no changes in resting free and total testosterone, especially in sedentary individuals.11 However, adding high intensity intervals (e.g. sprint intervals) just two times per week can increase total resting testosterone and testosterone to cortisol ratios in trained individuals.8 A research study showed that progressive maximal intensity exercise on a cycle ergometer increased testosterone by up to 30 percent at 20 minutes after beginning the exercise.13 In another study, six experienced male weight lifters had their testosterone levels measured during no training, a training session with four sets of moderate weight squats (six repetitions), and a training session with four sets of light weight squats (nine to 10 repetitions). Results showed that testosterone increased even at varying intensities of resistance training (both moderate weight lower rep, and light weight higher rep), but only after the fourth set.12 This indicates that volume is a significant factor in driving the androgen response.

Short Rest Intervals
1, 2, 5, 7

Some sources recommend 30 to 60-second rest intervals between sets, though this may be more indicative of the entire anabolic hormonal response.1, 2 Research comparing 60, 90, and 120-second rest periods showed that the testosterone increase was greater in the 90 and 120 second rest groups, with the highest level showing up in the 120 second group. However, growth hormone increase was greatest with the 60-second rest group.10 In order to maximize testosterone response, 90 to 120-second rest periods in between sets seems to be indicated.

Training Experience
1

Two years or more of training experience seems to be indicated to maximize increases in testosterone response to exercise. It is theorized that this has to do with an adaptive response in resistance-trained individuals. Acute elevations in free testosterone after resistance exercise was greater in resistance trained men than endurance trained men, which seems to support this theory of adaption.5 Other research indicated that the free testosterone increase was also greater after 10 weeks of periodized strength training compared with the pre-training response.5

<60 Minute Workouts
4

Research shows that testosterone can increase during the first 60 minutes of a workout, and then decreases thereafter. Testosterone levels may even drop as low as 25-50 percent lower than pre-workout levels.4 If it is necessary to perform exercise more than 60 minutes long, it would be beneficial to utilize a split routine, with one portion of the workout in the morning and the other later in the day. For competitive athletes, this time frame may not be realistic. Therefore, while negative effects from workouts >60 minutes cannot be negated, they may be mitigated or managed by proper nutrition and rest. For instance, ingesting carbohydrates immediately post-workout seems to decrease the overall output of the catabolic hormone cortisol. Increasing length of total sleep and/or taking 30 to 60-minute afternoon naps (if schedule permits) has also served as an effective strategy for managing the adverse effects of longer workouts.

A final consideration regarding exercise is the diurnal changes in testosterone, which is at its highest in the morning and decreases throughout the day. It may be beneficial to exercise later in the afternoon to increase overall daily testosterone concentration.1

References:
1. Baechle, Thomas R. & Earle, Roger W. (2008) Essentials of Strength Training and Conditioning 3rd Ed. Champaign, IL: Human Kinetics

2. Fleck, Steven J. & Kraemer, William J. Designing Resistance Training Programs 3rd Ed. (2004). Champaign, IL: Human Kinetics

3. Kraemer, William J., Fleck, Steven J., Deschenes, Michael R. (2012) Exercise Physiology: Integrating Theory and Application. Philadelphia, PA: Lippincott Williams & Wilkins

4. Kreider, Richard B., Fry, Andre C., and O’Toole, Mary L. (1998). Overtraining In Sport. Champaign, IL: Human Kinetics

5. Antonio, Jose, Kalmon, Douglas, Stout, Jeffrey R., Greenwood, Mike, Willoughby, Darryn S., & Haff, G. Gregory (2008). Essentials of Sports Nutrition and Supplements. Humana Press

6. Zatsiorsky, Vladimir M., Kraemer, William J. (2006) Science and practice of Strength Training 2nd Ed. Champaign, IL: Human Kinetics

7. Komi, Paavo V. (2003) Strength and Power In Sport 2nd Ed. Blackwell Science Ltd.

8. Farzad B, Gharakhanlou R, Agha-Alinejad H, Curby DG, Bayati M, Bahraminejad M, Mäestu J. Physiological and performance changes from the addition of a sprint interval program to wrestling training. J Strength Cond Res. 2011 Sep;25(9):2392-9.

9. Rønnestad BR, Nygaard H, Raastad T. Physiological elevation of endogenous hormones results in superior strength training adaptation. Eur J Appl Physiol. 2011 Sep;111(9):2249-59.

10. Rahimi R, Qaderi M, Faraji H, Boroujerdi SS. Effects of very short rest periods on hormonal responses to resistance exercise in men. J Strength Cond Res. 2010 Jul;24(7):1851-9.

11. Hiruntrakul A, Nanagara R, Emasithi A, Borer KT. Effect of endurance exercise on resting testosterone levels in sedentary subjects. Cent Eur J Public Health. 2010 Sep;18(3):169-72.

12. Schwab R, Johnson GO, Housh TJ, Kinder JE, Weir JP. Acute effects of different intensities of weight lifting on serum testosterone. Med Sci Sports Exerc. 1993 Dec;25(12):1381-5.

13. Cumming DC, Brunsting LA 3rd, Strich G, Ries AL, Rebar RW. Reproductive hormone increases in response to acute exercise in men. Med Sci Sports Exerc. 1986 Aug;18(4):369-73.

14. Crewther B, Cronin J, Keogh J, Cook C. The salivary testosterone and cortisol response to three loading schemes. J Strength Cond Res. 2008 Jan;22(1):250-5.