Training to Failure Every Set Is Not Conducive to Testosterone

For years, personal trainers and fitness experts told lifters that every set must be performed to absolute failure.  This type of advice should be revised as recent research reports that training to failure every set leads to reductions in anabolic hormones such as IGF-I and testosterone and caused larger increases in cortisol compared to lifters who don't train to failure.  The subjects in the study trained twice a week using a periodized weight training program for 16 weeks.  One group trained to complete muscular failure for each set while the other group trained did not complete sets to muscular failure.  The researchers defined muscular failure when the subjects could not perform a full extension or the weight was paused for more than 1 second during a repetition.  At the end of the 16 week study, training to failure over the 16 week study resulted in reductions in circulating IGF-I concentrations.  In addition, the group that did not train to failure had reduced resting cortisol concentrations and an elevation in resting serum total testosterone concentration after 11 weeks of training.  Additionally, the group that did not train to failure had similar increases in 1-repetition maximum strength gains in the bench press, parallel squat, and muscle power output of the arms and legs extensor muscles³⁶.     If you are trying to maximize size, than not training to failure may lead to enhanced testosterone and lower catabolic activity such as reduced cortisol.  The reduction in anabolic hormones (IGF-I and testosterone) from training to failure goes against decades of advice to train to failure for maximal muscle growth.

Overtraining Decreases Testosterone

Acute increase in testosterone occurs with resistance exercise but prolonged workouts with insufficient rest and recovery can lead to overtraining and reduced testosterone.  When subjects performed a high volume resistance training protocol which consisted of 50 total sets of upper and lower body exercise with repetitions of 5 and 10 RM loads with 90-second rest periods between sets resulted in no change in testosterone during exercise and immediately after exercise; shockingly there was a concomitant lower LH secretion and suppressed total and free testosterone for up to 13 hours after exercise¹⁰.  Another study monitored elite Olympic lifters testosterone concentrations to twice daily training for 1 week.  Elite Olympic weightlifters trained twice a day using similar volume (> 90% of a 1-RM) but different exercises.  The morning session (9:00 a.m. to 11:00 a.m.) consisted of Olympic snatches, clean & jerks, and front squats, while the afternoon session (3:00 p.m. to 5:00 p.m.) consisted of power snatches, power cleans, and back squats.  Testosterone started to decrease after the first training day and continued to systematically decrease over the course of the training period.  When the training stress was reduced to one training session a day, serum testosterone concentrations started to increase, and after 1 full day of rest, values returned to the pre-training level¹⁸.

Long Distance Running- Chemical Castration

Research has shown that men who have performed chronic endurance exercise training for many years have lower circulating basal concentrations of free and total testosterone³⁴. It has been reported that basal testosterone concentrations of long-distance runners were only 55-70% lower than those found in age-matched controls³⁵. The observed suppressed testosterone response may be due to a reduced number of LH receptors on the Leydig cells of the testis or a compromised testosterone conversion process in the testis. Investigators have speculated that the high cortisol produced during long endurance runs can suppress testicular function) or other physical events (i.e., increased testicular temperature due to thermic effects of exercise).

Dietary Cholesterol Increases Testosterone Production

Cholesterol is a pre-cursor for testosterone so increasing cholesterol production may promote more conversion into testosterone. An abstract presented at Experimental Biology reported that the conversion of cholesterol to testosterone may be important for muscle hypertrophy.  Adults were placed on a 12-week weight-training program and tested them before and after for changes in muscle mass and strength. While all subjects ate a diet that was moderate in protein, about half consumed a low-cholesterol diet (1.6 mg per pound of bodyweight or about 150-250 mg per day) while the other half consumed a high-cholesterol diet (2.6 mg per pound of bodyweight or about 250-450 mg per day). After 12 weeks of weight training, the lower-cholesterol group did not increase muscle mass but strength increased by 35%. The higher-cholesterol group, on the other hand, saw an increase in muscle mass of about 5 pounds and increased strength by about 90%.  Although the researchers were not sure exactly why cholesterol influences muscle and strength gains, the reason can be speculated: Cholesterol is important for testosterone production as well as maintaining the integrity of muscle cell membranes. In other words, cholesterol isn't all bad and may be necessary for building muscle and strength.  The increase in cholesterol could have lead to a boost in testosterone production.

Monounsaturated and Saturated fats Increase Testosterone

In addition to cholesterol, the type and amount of fat consumed regulate testosterone production as well. Reducing dietary fat from (>30 percent calories from fat and low fiber < 20 g/day) to a low fat diet (<15 percent calories as fat and 25-30g fat per day) significantly reduced total and free testosterone levels and adrenal androgens (androstendione and DHEA-S)⁴¹. It has been reported that when men consumed isocaloric diets (i.e. diets containing the same amount of calories) from low fat diets from vegetarian sources (~25% kcals from fat) resulted in significant decreases in testosterone and the nocturnal release of testosterone, compared to men receiving moderate fat diets (~40% kcals from fat)⁴².  Additionally, middle aged men fed a low fat (<25 % ), high fiber diet for 6 weeks, during a crossover intervention, experienced a significant decrease in testosterone and free testosterone. These participants experienced a return of testosterone and free testosterone levels to baseline when the subjects were reassigned to the moderate-fat diet (37 % fat)^43.   Total dietary fat, saturated fatty acids, and monounsaturated fats have been found to be positively correlated with resting T concentrations in men, whereas diets that are high in polyunsaturated fats are shown to be inversely correlated with T levels^{13, 36,37, 38.}  Additionally, rats that are fed diets rich in monounsaturated fats had greater 17b-dehydrogenase activity (a key enzyme in the testosterone synthesis pathway in the male rat) and plasma androgen concentrations compared to rats fed diets rich in saturated and polyunsaturated fats³⁹.  It has been shown that when isocaloric meals that contain different proteins and different quantities and type of fat are administered to subjects, meals with a high polyunsaturated to saturated fats ratio result in significant reductions in testosterone levels.  Hamalainen et al. reported that there was a 15% reduction in serum T concentrations accompanied by a significant decrease in androstenedione levels when subjects were switched from a diet rich in animal fats to a diet low in saturated fats and high in polyunsaturated fats⁴⁰.