With all the exercise training fads out there, it can be hard to navigate the landscape with diabetes. I am frequently asked about the latest training techniques or gym trends, so I want to specifically address a recent craze, CrossFit training, with regard to whether it’s appropriate and/or advisable for people with diabetes.
In brief, CrossFit training is a strength and conditioning program consisting mainly of a mix of aerobic exercise, gymnastics (body weight exercises), and Olympic weight lifting. Its programming is decentralized, but its general methodology is used by thousands of private affiliated gyms around the world. CrossFit, Inc., licenses the CrossFit name to gyms for an annual fee and certifies trainers, but the actual programs vary tremendously from site to site.
A concerned young man with type 1 diabetes contacted me to ask whether it’s safe for him to do CrossFit. Although he was already doing and benefiting from CrossFit training, he became concerned about it after reading a blog online by a Paleo diet advocate named Robb Wolf who, in an article about CrossFit training and type 1 diabetes, blogged that since intense training causes the liver to release excess glucose during training, people with type 1 diabetes “may be better served by mild to low intensity activities. Power Lifting, due to the low volume, might be a good option.” (This blogger also claimed that “We have seen instance of people REVERSING type 1 diabetes with a Paleo diet because they put their autoimmunity in remission.” That statement alone should make you question his credibility. If you really want to read it, please just don't believe everything you read online, especially his blog: http://robbwolf.com/2009/08/05/type-1-diabetes-and-crossfit/#sthash.CIZdVMvp.dpu.)
My perspective is that, if you’re young and healthy and just happen to have diabetes, you should be able to engage in CrossFit training without worrying excessively about your blood glucose levels going up temporarily from doing it. To control your blood glucose, you simply have to approach it like any other intense workout, which can cause your blood glucose to go up even in people without diabetes. If you use insulin, you’ll just need to check your glucose frequently and adjust your insulin doses to make sure you have enough to stay in control both during and following your CrossFit (or other) workouts. As a side note, doing some easy cardio exercise after an intense workout can help lower your blood glucose naturally. Also, keep in mind that you’re more likely to have a bigger rise in the early AM compared to doing the same exact training later in the day (due to having more glucose-raising hormones and less insulin on board in the morning, pre-breakfast).
CrossFit does carry some risks, however. The risk of injury from some of its exercises outweighs their benefits when they are performed with poor form in timed workouts (although there are similar risks from doing other high-intensity programs incorrectly). One concern in particular is that CrossFit's extensive online community enables anyone to follow the program without proper guidance, increasing the risk of improper form or technique that leads to getting injured. I have heard of at least one young man who caused significant damage to the cartilage in both of his knees doing such training inappropriately. When undertaken correctly, CrossFit is not inherently bad or ineffective, but beginning exercisers starting such a program may be encouraged to do too much and not be able to discern between training to failure and simply getting a good workout.
By way of example, a young woman who was a physical therapist and a regular CrossFit participant woke the morning after a particularly grueling session consisting of hundreds of reps of arm exercises and found she could not bend her elbows. She was diagnosed in the emergency room with rhabdomyolysis (“rhabdo” for short), a condition in which damaged muscles break down rapidly. This is not the first time CrossFit has been associated with rhabdo as the workouts can be particularly grueling and excessive, although any strenuous exercise can cause it. It’s worrisome because rhabdo can lead to kidney failure when excess breakdown products of damaged muscle cells (myoglobin) are released into your blood (see a video by the Mayo Clinic about exercise-associated rhabdo: https://www.youtube.com/watch?v=Hy0uEPo8-7w). Severe symptoms like muscle pain, vomiting, and confusion are symptoms of greater muscle damage and possible kidney failure. If you ever have severe muscle pain and dark colored urine, get medical attention immediately.