Insulin & Bodybuilding
The use of ergogenic substances such as anabolic androgenic steroids (AAS), erythropoietin (EPO) and gamma-hydroxybutyrate (GHB) has been growing among bodybuilders. More than a decade ago, a medical study found that steroid users also self-administer insulin and face the risk of hypoglycaemia, a condition where blood sugar level drops below normal, leading to severe consequences such as brain damage, seizures and coma.
Insulin has been postulated to be a potent anabolic stimulus. This is supported by a study demonstrating increased muscle protein synthesis (MPS) and reduced muscle protein breakdown (MPB) when hyperinsulinaemia (higher than normal blood level of insulin) is induced in young healthy participants. Given that insulin prevents MPB by promoting entry of glucose and amino acids into muscles, it is used as an adjunct to the anabolic effects of steroids. At a cellular level, insulin (stimulated by consuming glucose or through injection) and amino acids have an important role in the muscle cells’ signalling pathway involving the mammalian target of rapamycin (mTOR), thereby leading to a potent activation of MPS.
Insulin Side Effects
The serious health risk posed by self-administering insulin is well recognised. Furthermore, most steroid users have come to discover insulin by word-of-mouth and thus, lack proper medical supervision. Recently, another study pointed out that amino acids have to be taken in conjunction with carbohydrates to maximise the anabolic effects of insulin. Hence, the effectiveness of insulin alone in significantly stimulating MPS is only supported by anecdotal evidence. Additionally, a myriad of factors such as amino acids, testosterone, growth hormone, insulin-like growth factor and most importantly physical exercise all have important roles in promoting MPS.
A safer alternative to apply the beneficial effects of insulin to our workout is to aim for recovery. Consuming moderate to high glycaemic index(GI) carbohydrates immediately post-workout is important to replenish glycogen stores and improving performance in subsequent sessions (refer to “Carbs and Training” article). In the long term, it would definitely be wiser to avoid the risk of insulin abuse, and to sustain and continuously improve workout performance through proper nutrition and training regime.
1 Burke, LM, B Kiens and JL Ivy, 'Carbohydrates and fat for training and recovery' Journal of Sports Sciences. (2004) 22(1) 15
2 Evans, PJ and RM Lynch, 'Insulin as a drug of abuse in body building' British journal of sports medicine. (2003) 37(4) 356
3 Fujita, S et al, 'Aerobic exercise overcomes the age-related insulin resistance of muscle protein metabolism by improving endothelial function and Akt/mammalian target of rapamycin signaling' Diabetes (2007) 56(6):1615
4 Koopman, R et al, 'Coingestion of carbohydrate with protein does not further augment postexercise muscle protein synthesis' American Journal of Physiology- Endocrinology And Metabolism. (2007) 293(3): E833
5 Rich, JD et al, 'Insulin use by bodybuilders' Jama. (1998) 279(20): 1613
6. Tipton, KD and AA Ferrando, 'Improving muscle mass: response of muscle metabolism to exercise, nutrition and anabolic agents' Essays Biochem. (2008) 44: 85