Boosting – time to be aware

Most Sports Physicians are well aware of the issue of doping in elite sport and many of the methods used by sports participants. However, some of us may well not have come across a method used by some athletes with a disability called ‘Boosting.’ With the forthcoming Paralympics just around the corner, now is the time to consider this method of doping for those of us who are involved with events later on this year in London 2012.

Some athletes with a high level spinal cord injury (T6 and above) may voluntarily induce an episode of autonomic dysreflexia (AD) prior to, or during, an event in order to enhance their performance. A variety of methods may be used by athletes, including clamping catheters, sitting on sharp objects, and using tight leg straps.

The resulting physiological response leads to a significantly raised blood pressure, with improved blood flow to working muscles. The performance enhancement that may ensue as a result of this response may be significant and lead to an improvement in VO2.

It is not always easy to determine whether or not a deliberate attempt to induce AD has taken place as AD is not uncommonly caused by a number of common triggers including urinary retention due to catheter blockage or misplacement, infections, constipation, or noxious stimuli from other sources such as pain due to a lower limb injury.

My first clinical encounter with a patient with AD was during my registrar training when I was working on a spinal cord injuries unit (SCIU) – the cause on that occasion was a blocked catheter. Recognition was swift due to the awareness of the ward nursing staff to the condition. The patient was treated with nifedipine plus a catheter replacement and bladder washout, and made a swift and uneventful recovery. I was to encounter a few more episodes of AD occurring in in-patients during the next 6 months when I was working on the SCIU.

Whilst not only banned by the International Paralympic Committee as a doping method, boosting is dangerous to the health of athletes and may lead to a hypertensive crisis, stroke and death.

The signs and symptoms of mild-to-moderate AD include piloerection, sweating above the level of the spinal cord lesion, headaches, blurred vision, bradycardia, facial flushing, nasal congestion and anxiety. Systolic blood pressure may rise to over 250mmHg.

Athletes are routinely checked prior to competition for any of these signs and symptoms, and repeated blood pressure measurements are taken if there is any suspicion of boosting or AD. If a systolic blood pressure of 180mm Hg or higher is persistently measured, then the athlete is not allowed to compete in the event and possible causes of AD are searched for.

In this month’s Thematic issue of the Clinical Journal of Sport Medicine on Paralympic Sports Medicine, our featured freely-available article by Krassioukov focuses on blood pressure control and AD in athletes, discussing the physiological mechanisms behind this doping method and what we know about the practice of boosting.

For those who may wish to raise awareness of boosting as a doping method, there is a useful presentation on AD and boosting available on the official website of the Paralympic movement, funded in part by the World Anti Doping Agency (WADA) and the IPC.

(Image of Iran v South Africa at 2008 Paralympic games available at Wikimedia Commons, and Autonomic Nervous System originally from ‘Gray’s Anatomy’ )

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