safety

Should You Race When You’re Sick?

July 23, 2017 By Larry Creswell, MD Leave a Comment

We’ve had a fair amount of discussion here at the blog about long-term health, chronic heart conditions, and how exercise may or not be safe. We haven’t talked much, though, about acute general medical conditions, such as simply being “sick.”

Should you race when you’re sick? And, if you do….what might the consequences be?

I had a recent conversation with Chad Asplund, MD, the medical director for one of the Ironman 70.3 races, and Jon Drezner, MD, team physician for the Seattle Seahawks and an editor for the British Journal of Sports Medicine. We were talking about making a list of the concrete steps that triathletes could take to avoid serious medical problems on race day. Dr. Drezner drew my attention to a scientific report from last year that addressed this issue in long-distance running.

Let’s take a look at the study.

The Study

The team of investigators, from Cape Town, South Africa, is involved in the race-related medical care for a collection of on- and off-road running events ranging from “fun runs” to the 56-km Two Oceans Marathon, involving more than 25,000 runners each year. Over the past several years, this group has focused on studying this athlete population with an eye toward identifying, introducing, and testing interventions that might decrease the risk of race-day medical complications in participating runners. Collectively, their work has become known as the SAFER (Strategies to reduce Adverse medical events for the ExerciseR) studies. I’ve previously written here at the blog about the SAFER I study that looked at the “medical toll” of running races.

In the SAFER IV study, the investigators studied the impact of pre-race acute medical illness and do not start (DNS) and do not finish (DNF) rates for runners who competed one year in the 10-km or 22-km trail runs or the 21.1-km or 56-km Two Oceans events (1).

In the 3-5 days before each race, participants were offered the opportunity to complete an online questionnaire about any acute medical symptoms or illnesses that were present pre-race. The questionnaire included both systemic symptoms (headache, general muscle pains, cough, general joint pains, fever) and non-systemic symptoms (sore throat, runny nose, general tiredness, blocked nose, diarrhea, sore ears, abdominal pain, nausea, wheezing, bladder infection, skin rash, vomiting).

Among the participants, 7,031 runners completed the questionnaire. Any runners who reported symptoms received by email some educational material that suggested they not return to running until all symptoms were gone and they felt well again.

The Findings

A total of 19% of respondents reported at least one symptom during the pre-race period; this included 7.5% who reported systemic symptoms. The remaining 81% reported no symptoms (the control group).

In the control group, the DNS rate was 6.6%. In the symptomatic group, the DNS rate was 11.0%. Interestingly, despite the availability of the educational information for the symptomatic group (that recommended not exercising until runners felt well), 89% of those athletes started the race. For those runners who reported any systemic symptoms, the DNS rate was 15.1%.

In the control group, the DNF rate was 1.3%. In the symptomatic group who started the race, the DNF rate was 2.1% (1.6 times greater than control). For those runners who reported any systemic symptoms and who started the race, the DNF rate was 2.4% (1.9 times greater than control).

The investigators concluded: 1) symptoms of acute illness were relatively common during the pre-race period; 2) despite such symptoms and despite educational materials that discouraged participation, most athletes chose to start the race; and 3) pre-race symptoms of acute illness significantly increased the chances for a DNF.

My Take on The Study

This study is intriguing because it is the only prospective study to address the impact of pre-race acute illness on race-related performance, in any sport. First, a couple notes about the study’s limitations are in order.

First, the response rate for the pre-race survey was rather low (26.6%). The authors indicate that the respondents did not differ substantially from non-respondents in terms of demographic data, but whenever a survey response rate is low, there is a possibility of unwanted bias.

Second, no information is available on the reasons for any athlete’s DNF. Clearly, it would be more informative if pre-race symptoms could be correlated with specific race-day medical problems that might cause the athlete to DNF.

In spite of those limitations, the investigators make some important observations in their running population, but these observations can probably be generalized to other athlete populations:

Nearly 1 in 5 athletes were “sick” in the days leading up to their race. This is a lot of participants.
The vast majority of “sick” athletes probably ignored warnings about participating until they were well (although certainly some may have felt better by race day).
Pre-race “sickness” with systemic symptoms was associated with a nearly doubled risk of DNF. That’s a big effect on performance, even if finer distinctions such as finishing times could not be discerned.

Thinking about the implications, athletes and their physicians should be aware of the potential negative consequences of racing when “sick.” Race organizers should consider distributing educational information about these negative consequences, while recognizing that athletes may not accept unwanted advice not to participate. Many factors (investment in training, scheduled time off from work, costs associated with the race/travel) may be barriers in athletes’ acceptance of such advice. Lastly, additional studies would be helpful if they examined: 1) race-day medical conditions and their relationship with pre-race symptoms; and 2) other measures of performance such as actual versus expected finishing times.

Reference:

Van Tonder A, Schwellnus M, Swanevelder S, Jordaan E, Derman W, Janse van Rensburg DC. A prospective cohort study of 7031 distance runners shows that 1 in 13 report systemic symptoms of acute illness in the 8-12 day period before a race, increasing their risk of not finishing the race 1.9 times for those runners who started the race: SAFER study IV. Br J Sports Med 2016; 50:939-945.

Related Posts:

The Medical Toll at Endurance Events

Triathlon, Open Water Swimming, and the Heart: What Can We Learn From Dolphins and Seals?

March 16, 2015 By Larry Creswell, MD Leave a Comment

A recent study about marine mammals caught my eye. I don’t know much about non-human biology and physiology, but this study on dolphins and seals may shed some light on the problem of fatalities during open water swimming or triathlon events.

The Study

A group of investigators headed by Terrie Williams from the University of California at Santa Cruz shared their report, “Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals” in the January 16th edition of Nature Communications (1).

This group of investigators has been interested in the physiology of the so-called “dive response” in marine mammals. This is a response that is governed by the involuntary, or autonomic, nervous system, which has two antagonistic components: the parasympathetic nervous system and the sympathetic nervous system. As a group, the marine mammals depend on feeding by chasing pray to depths that can range up to 3,000 m. Even at lesser depths, these mammals must maintain a breath-hold under large hydrostatic pressures while they undergo extreme exertion to catch their pray. During a dive, breath-holding stimulates the parasympathetic nervous system to slow the heart rate (producing bradycardia). At the same time, the exertion required to chase pray stimulates the sympathetic nervous system, producing an increase in the heart rate. The current study offers the first detailed study of the interplay between the components of the autonomic nervous system during routine diving and feeding activity in these animals.

The investigators created an electrocardiograph-accelerometer depth monitor that was deployed on 10 Atlantic bottle-nosed dolphins and 3 Weddell seals. This device allowed high-fidelity recording of the heart rate, ECG, water depth, and swimming stroke frequency (a measure of exertion) during dives. For the dolphins, measurements were made for 74 dives to depths of up to 210 m. For the seals, measurements were made for 91 dives to depths of up to 390 m.

The Results

As expected, there was a strong relationship between diving depth and heart rate for both species, with heart rates falling during descent and reaching a minimum at the lowest depth of the dive. Superimposed on this effect was an additional effect of exertion. For the dolphins, the maximum heart rate was 1.7 to 3.7 times greater during periods of extreme exercise compared to gliding alone. For the seals, the maximum heart rate was 1.5 to 1.8 times greater during periods of extreme exercise compared to gliding alone.

The surprising finding was that cardiac arrhythmias occurred in more than 73% of the dives. The investigators defined arrhythmias to include ectopic beats or significantly increased variability in the interbeat interval (IBI). There were apparently no sustained or fatal arrhythmias., but there were discrete examples of “wandering pacemaker” and ventricular premature beats. In the Weddell seals, there were often patterns of alternating periods of tachycardia (fast heart rate) and bradycardia (low heart rate) during periods of constant, intense exertion.

The presence of cardiac arrhythmias was strongly correlated with increased depth of dive (parasympathetic activation) and increased exertion (sympathetic activation). As an example, cardiac arrhythmias occurred in 81% of the dolphin dives to >210 m but in only 26% of dives to <100 m.

The authors concluded that our previous understanding of the dive reflex in marine mammals was not totally correct. Given that these animals depend on diving for their food sources, the development of cardiac arrhythmias during feeding appears to be mal-adaptive. In fact, feeding might actually be dangerous.

My Thoughts

At first glance, the physiology of the diving response of dolphins and seals during feeding seems far afield from open water swimming and triathlon. And moreover, we already know about the development of cardiac arrhythmias during submersion in breath-holding humans as well as other marine species. The important observation here, though, is what I might call “irritability” or “instability” in the heart rhythm during periods of intense parasympathetic and intense sympathetic activation….and that’s the possible link to human fatalities during open water swimming or triathlon.

We know from autopsy reports of triathletes who’ve died during the swim portion of an event that there are sometimes only subtle abnormalities of the heart, and often nothing that seems explanatory. That leaves us in a difficult position to explain such deaths. In a previous blog post, I wrote about one very plausible hypothesis. Two UK physiologist,s X and X, proposed the concept of “autonomic conflict,” where a surge in both the parasympathetic and sympathetic stimulation of the heart might lead to a fatal arrhythmia. I’ve been intrigued with this hypothesis because it seems to fit many of the observations made about the swim victims. It is easy to see where exertion, cold water, anxiety, etc. might lead to strong sympathetic activation. And it’s equally easy to see where facial wetting, water entering the mouth/hypopharynx/nasopharynx, and breath-holding, even without diving, might lead to strong parasympathetic activation. In that instant, in an athlete with some sort of susceptible heart, a fatal arrhythmia might occur.

The new observations about the dolphins and seals seem to play into this hypothesis.

2. Triathlon Fatalities: 2013 in Review

Reference:

1. Williams TM, Fuirman LA, Kendall T, et al. Exercise at depth alters bradycardia and incidence of cardiac anomalies in deep-diving marine mammals. Nature Communications 2015;6:6055.

Medical Toll at Obstacle Race

July 6, 2014 By Larry Creswell, MD 1 Comment

Obstacle

A couple weeks ago I wrote about the medical toll at long-distance running events. There was also a recent report on the medical toll at an obstacle course race that caught my eye. On the face of it, the findings were surprising!

At the outset, let me issue a disclaimer. I haven’t participated–or even spectated–at one of these obstacle course races, so I may not have the best perspective. I’m talking, though, about races like the Tough Mudder, Warrior Dash, and Spartan Race, among others. They’ve become very, very popular very, very quickly. We’re talking 100’s of thousands of participants per year in the U.S. One day, I’ll give it a try. I’ll need to be brave!

The Study

A group of investigators headed by Marna Greenberg, DO, MPH, in the Department of Emergency Medicine at Lehigh Valley Hospital reported on a collection of patients who required hospital care stemming from their participation in an obstacle course race. The event was the Tough Mudder Philadelphia race, held over the weekend of June 1, 2013. As you may know, the Tough Mudder races are characterized by a 10- to 12-mile course with a series of 20-25 obstacles spread over the course. By report, approximately 22,000 individuals participated in this particular race.

The investigators were the emergency room physicians at the hospital that was designated to care for participants who required hospital care for medical conditions or injuries that developed during the race. In a report in the Annals of Emergency Medicine entitled “Unique Obstacle Race Injuries at an Extreme Sports Event: A Case Series”, they share their first-hand experience which they characterized as surprising.

The Results

The report provides fair detail about 5 patients with “significant” injuries or diagnoses and compiles a list with pertinent findings in 43 total athletes who received care at the hospital. The 5 athletes with “significant” problems included:

18 year old with myocarditis (inflammation of the heart muscle) caused by electrical shock during the event. Required admission for 2 days. Self-limited.
28 year old with depressed level of consciousness and diagnoses of accelerated hypertension (high blood pressure) and pericarditis (inflammation of the sac that holds the heart). Required admission for 2 days. Self-limited.
31 year old right-sided weakness who was found to have a stroke, seizure, and dehydration. Required admission to the intensive care unit (ICU). Was discharged to a rehab facility and at the time of writing, had persistent weakness due to the stroke.
41 year old who experienced syncope (blacked out) after being shocked at an obstacle. He fell, causing lacerations to the face. He was discharged from the emergency room against medical advice to be hospitalized.
25 year old woman with near syncope (nearly blacking out) because of electrical shock. Required hospitalization for evaluation and was treated for dehydration and rhabdomyolosis (breakdown of muscle).

The 38 others had diagnoses that included: heat injury, sunburn, ear barotrauma (pressure injury), shoulder dislocation, patella dislocation, heat exhaustion, vomiting, renal failure, various contusion injuries, rib fracture, dehydration, asthma, seizure, leg fracture, ankle sprain, and elbow sprain, among others.

The Takehome Messages

You never read about the medical toll at running races that are shorter than half marathon distance. That’s not to say that athletes don’t have injuries or other medical problems manifest during those races. It’s just that athletes are usually responsible for their own medical care or receive their care from the emergency medical system (EMS), rather than by race-supplied medical volunteers. So nobody is keeping track of the “toll.”

This report is great peak into the issues with the obstacle races. Kudos to the authors for sharing their experience. Obviously, 43 victims among 22,000 participants is a small fraction. We might reasonably expect, though, that additional athletes with minor injuries or medical conditions did not visit the hospital for care.

Some thoughts….

At an obstacle course race, the obstacles present a challenge and risk that is different from just running. These events are certainly not risk-free.
There are typical medical issues like minor injuries, dehydration, and heat injury. Some injuries and medical problems may be due very specifically to the obstacles themselves.
There will also be injuries that may not be expected–either by the athletes or by the nearby healthcare workers. At this particular event, the myocarditis, pericarditis, stroke/seizure, and syncope diagnoses were examples. Electrical shock was an unexpected causative factor.
Athletes should keep the potential risks in mind when they decide to participate and exercise great care while participating.

Like I said at the top, I’ll probably be a participant at some point. But I’ll need to be brave!

The Medical Toll at Endurance Events

June 16, 2014 By Larry Creswell, MD 2 Comments

Have you wondered about the “medical toll” at endurance sports events? By that, I mean the sum of all the medical problems that occur to atletes during their participation (and perhaps shortly afterwards as well).

It’s an interesting issue, with many practical implications. If you’re organizing a swim meet, you’d be interested in the likelihood of drowning. If you’re participating in a bicycle race, you’d be interested in the frequency of crash-related traumatic injuries. If you’re the spouse of a long-distance runner, you’d be interested in the likelihood of heart-problems for the participants of a marathon. Should your event have a “medical tent” to handle anticipated injuries or medical problems? Where should the medical tent be located and how should it be staffed? How should your local EMS system or hospital prepare to handle athlete-patients? You get the idea.

Yet surprisingly little has been written in the medical and scientific literature about the medical toll of endurance events. There’s probably a bunch of reasons, including the fact that nobody in particular’s keeping track.

This past week there was an interesting report in the British Medical Journal from a group of investigators in Cape Town, South Africa, and headed by Martin Schwellnus. The report, “Medical complications and deaths in 21 and 56 km road race runners: a 4-year prospective study in 65,865 runners–SAFER study I,” describes the “medical toll” at recent editions of the Two Oceans Marathon races. The report and the findings caught my eye.

The Study

The participants in the study were the 65,865 runners who took part in either the 21 km half marathon or 56 km ultra marathon, the premier events at the Two Oceans Marathon races that are held each year in Cape Town, South Africa. They focused on the 2008 through 2011 editions. The weather conditions for these races was generally favorable, with temperatures ranging from 11.5 to 18.2 degress C and relative humidity ranging from 77% to 93%.

Like many long distance running events, these races had an elaborate set-up for provision of medical care on race day, including on-route medical stations, a dedicated medical facility at the finish, and designated hospitals where athlete-patients would be transferred should they need emergency care. Because the system for medical care was so well proscribed, the investigators were able to compile a list of all “medical complications” that occured in the race participants.

The investigators did not consider the most minor of medical complications, such as seeking medical attention at various first-aid stations for minor injuries or requiring physical therapy attention at the finish line. For simplicity, “medical complication” was defined as an episode that required the attention of a doctor. Exercise-associated muscle cramps alone were not considered a “medical complication” unless there were additional symptoms such as confusion, dizziness, nausea, or vomiting. A serious medical complication was defined as a “medical complication that could result in death unless urgently diagnoses and treated.” And finally, deaths were recorded as well.

The Results

Of the 65,865 participants, 64,420 (97.8%) finished their race(s). The finishing rate was 99% for the 21 km races and 97% for the 56 km races.

Two deaths were documented, each in a 21 km race. The fatality rate, then, was approximately 1 per 20,000 participants in the 21 km races. There were no deaths in the 56 km races.

Overall, there were 545 medical complications among the 65,865 participants, a rate of approximately 0.8% (8.27 per 1000 participants). The rate was approximately 0.5% for participants in the 21 km races and 1.3% for participants in the 56 km races.

Included in the 545 total medical complications were 37 that were designated as serious medical complications. This is a rate of approximately 0.06% (0.56 per 1000 participants). There was no significant difference in the overall rate of serious medical complications based on the distance of the race. The serious life-threatening medical complications included:

Ischemic heart disease (including successful resuscitation from cardiac arrest), in 3 runners
Myocarditis, in 2 runners
Serious cardiac arrhythmias, in 2 runners
Symptomatic hyponatremia (low sodium), in 9 runners
Serious metabolic complications, in 5 runners
Serious heat-related disorders in 7 runners (1 with hypothermia, 6 with hyperthermia)
Pulmonary edema, in 2 runners
Serious fluid, electrolyte, or acid-base abnormalities, in 4 runners
Bronchospasm, in 2 runners
Convulsions, in 1 runner

Further statistical analysis was used to evaluate groups of medical complications, depending upon the body’s organ system that was involved. In this analysis, the frequency of complications involving the cardiovascular, musculoskeletal, metabolic, gastrointestinal, and respiratory systems was greater among the 56 km runners than for the 21 km runners.

The Takehome Messages

The chances of a medical complication or serious medical complication were small, for both of the race distances. Athletes should know, then, that these risks are small as they consider participation in an event.

Information like this should inform safety planning on the part of event directors, event medical directors, and events’ local medical communities.

I suspect that the results are generalizable to races outside of South Africa and also to the real-world question of half marathon vs. marathon races which would be typical distances in the United States.

It is a somewhat surprising finding that the only 2 deaths occurred in the shorter, 21 km races. We know from recent detailed studies involving millions of runners that the risk of sudden cardiac arrest at long-distance running events is almost 3 times higher for marathon runners than for half marathon runners. In this study, it’s a statistical oddity–that not enough years were considered to evaluate such a rare end point.

Intuitively, it is not surprising that there would be more medical complications in the longer events. If nothing else, there is more “time exposure”–more athlete-hours spent in strenuous exercise.

I am surprised, though, that the frequency of serious, life-threatening, medical complications was similar for the 2 race distances, I would have guessed that these, too, would be more common in the longer distance races. Perhaps the take home message is the converse–that a shorter race is not necessarily safer when it comes to life-threatening medical complications. And the real world consequence would be that half marathoners not give short shrift to their health before participating.

Lastly, I’ll continue to hope that national governing bodies and large event organizers (eg, World Triathlon Corporation [WTC[) might collect and disseminate information about the “medical toll” at their races. As a sporting community, we would all benefit.