Can weight training significantly decrease Sex Hormone-Binding Globulin (SHBG) levels?

Effect of Weight Training on Sex Hormone-Binding Globulin (SHBG)

Weight training can significantly increase SHBG levels, particularly in overweight and obese individuals. 1

Mechanisms and Evidence

• Resistance training has been shown to increase SHBG levels in overweight/obese young men without requiring weight loss, while simultaneously decreasing free androgen index (FAI) 1
• This effect occurs concurrently with beneficial changes in body composition, including increases in lean body mass and decreases in total and trunk fat mass 1
• The increase in SHBG from resistance training may contribute to improved glucose metabolism, as demonstrated by decreases in glucose and insulin area under the curve following training 1
• A systematic review found that various exercise training programs, including resistance training, increased basal levels of SHBG in both males and females over 40 years of age, regardless of the mode, duration, and intensity of training 2

Physiological Context

• SHBG plays a crucial role in regulating the bioavailability of sex hormones, particularly testosterone 3
• Low SHBG levels are associated with obesity, insulin resistance, and increased risk of type 2 diabetes 1
• Adequate energy availability is essential for maintaining normal hormone levels - energy deficiency can significantly reduce testosterone in both male and female athletes 3
• Carbohydrate restriction during intense training can significantly affect testosterone responses 3

Clinical Considerations

• Both aerobic and resistance training improve insulin action, blood glucose control, and fat metabolism in muscle 4
• Resistance exercise specifically enhances skeletal muscle mass, which may contribute to improved metabolic health 4
• Excessive exercise with inadequate energy intake can lead to hormonal suppression (hypogonadism) in both men and women 3
• Weight loss in obese individuals can increase testosterone levels by improving hormonal imbalance 3

Recommendations for Exercise Implementation

• For general health benefits, individuals should undertake at least 150 minutes/week of moderate to vigorous aerobic exercise spread across at least 3 days per week 4
• Resistance training should be performed at least 2-3 times per week, targeting all major muscle groups 4
• Initial resistance training intensity should correspond to 30-40% of one-repetition maximum (1-RM) for upper body and 50-60% of 1-RM for lower body exercises 4
• Most studies showing hormonal benefits used training workloads of 50-80% of 1-RM 4
• Proper recovery between training sessions is essential for maintaining normal hormonal function 3

Potential Pitfalls and Caveats

• Excessive endurance exercise without adequate recovery can lead to decreased testosterone levels 3
• Energy balance is crucial - excessive exercise with inadequate energy intake can negatively impact hormonal health 3
• The temporary nature of exercise-induced testosterone elevation is well-documented, with levels typically returning to baseline within hours after exercise 3
• Persistently elevated or decreased hormone levels not explained by exercise should prompt further investigation 3

Weight training represents an effective strategy for increasing SHBG levels, particularly in overweight and obese individuals, which may contribute to improved metabolic health and reduced risk of related conditions.