Few hormones are so unfairly demonized as insulin. To read the popular media, insulin is the devil – the cause of obesity, type 2 diabetes and cardiovascular disease. A search on the internet brings up thousands of negative articles. Insulin is the driving force behind the low carb diet trend. The problem with the demonization of insulin is that it is more exaggeration than fact. Yes, poor diet can cause insulin related problems. Yes, a high fat diet can produce insulin resistance and type 2 diabetes. However that is not a true representation of the vital role insulin plays in enhancing endurance performance. Years ago I named insulin the "master recovery hormone" and hundreds of research studies have confirmed that fact. Insulin is a remarkable hormone and for endurance athletes it may be the most essential hormone. Here’s why.
1. It can be argued that no other anabolic hormone plays as critical role in repairing and rebuilding muscle protein and building lean body mass. Insulin increase amino acid transport into muscles where it can be manufactured into muscle protein. Insulin activates the pathway responsible for turning on muscle protein synthesis and last, but not least, insulin inhibits protein degradation, an important benefit post exercise.
2. Insulin is critical for replenishing muscle energy stores by increasing glucose transport into the muscle where it can be synthesized into glycogen. And insulin activates the pathway for the manufacture of muscle glycogen.
3. Insulin suppresses cortisol release which may offer a benefit in maintaining immune function.
4. Insulin increases blood flow facilitating the transport of nutrients and oxygen to muscles.
The bottom line – for the endurance athlete insulin is not a foe it's a great friend. It plays a vital role in recovery and helps raise the training level by controlling the quality of muscle recovery. So next time you read a negative article about insulin put it in perspective. For endurance athlete there is no better training partner.