With Dr. Rankin
Is it too hot to ride a bike? It has been really humid with all the rain lately and soaring summer temps are here for good. Just check the STRAVA ride titles! As cyclists we spend a lot of time out in the elements. Recently on a couple 90° rides I started thinking (when I could think) about heat exhaustion and rider safety. I thought it would be a good follow up to the previous article on hydration. So, I checked in with Dr. Rankin to discuss heat exhaustion.
OCA: How does the body regulate its temperature?
JR: This process is actually a very interesting process that is directed by a small part of the brain called the hypothalamus. It reacts to subtle differences in temperature generated from external and internal processes to keep the body temperature within a degree or two of 98.6F. On hot days and during exercise, they hypothalamus sends messages to the blood vessels, sweat glands, and skin setting off a process by which the blood vessels on the skin dilate bringing warm blood, water, and electrolytes to the skin. The sweat glands secrete the water and electrolytes onto the skin. The process of the fluids (sweat) evaporating from the skin lowers the body temperature.
OCA: At what point is the body unable to keep up with the heat?
JR: Eventually, when someone is in extreme heat and humidity for an extended time, the evaporation process fails. This is caused by the depletion of the body’s fluids and electrolytes that are secreted by the sweat glands. As this process fails, body temperatures soar which results in heat illness.
OCA: What is heat exhaustion? Symptoms?
JR: Heat exhaustion is an example of heat related illness. It isn’t as serious as heat stroke, but isn’t something to be taken lightly either. Generally, heat exhaustion is due to water depletion or salt depletion or a combination of both. Common symptoms of heat exhaustion include dizziness, headache, muscle/abdominal cramps, nausea/vomiting/diarrhea, and fatigue among others.
OCA: What should a person do if they are (or with someone who is) experiencing these symptoms?
JR: Well, initially making sure you have access to water and ideally some form of electrolyte replacement is recommended especially if symptoms are mild. Of course stopping the inciting activity and moving to a cooler environment would also be advised especially if symptoms are progressing rapidly. A cool bath/shower (or a dip in the river at Brentwood as I saw some of my fellow riders doing this past Tuesday) will also help decrease body temperature. One thing a lot of people don’t realize is that certain medical conditions (like heart, lung, kidney diseases and diabetes) and certain medications (like stimulants, diuretics, heart and blood pressure medications) can make someone more susceptible to heat exhaustion. Therefore, treatment for heat illness in these individuals should be a little more aggressive.
OCA: I know you train a lot for triathlon in the summer. Have you run into any cases (personal experience or others) of heat exhaustion while training or competing?
JR: Absolutely. As I alluded to in a previous article, when I competed in an IronMan in September, I became dehydrated and suffered heat exhaustion personally. I was super fatigued (but who isn’t after an IronMan), but was nauseated and had the abdominal cramps and headache like I mentioned above. I tried to replace as much fluid and electrolytes as I could during and after the race, but wasn’t getting anywhere fast. I wound up in the medical tent and after cooling under a fan and getting a bag of IV fluids, I managed to feel better. But even on local group rides, I see people with signs of heat related issues when they haven’t been drinking enough fluids and aren’t replacing their electrolytes sufficiently. Most of the symptoms are mild though and include cramping and fatigue.
OCA: Do you have any tips for steering clear of heat exhaustion and other heat related injuries?
JR: It’s mostly about prevention. Making sure you’re properly hydrated before a ride and taking in sufficient fluids and electrolytes during exercise is key. As discussed in a previous article, the amount of hydration/electrolytes needed varies from person to person. Also being aware of the weather conditions and heat index can be helpful. If you are able to, try to plan your ride/workout during the morning or evening when temperatures are somewhat lower. If you do suffer some type of heat related illness, keep in mind that after recovering from heat exhaustion, you may be more sensitive to high temperatures for the following week. So it’s probably not the best idea to jump right back in.
OCA: Heat related injuries can be dangerous. A big thanks to Dr. Rankin for taking the time to interview. As he mentions, it is mostly about prevention. Make wise decisions out there folks to steer clear of heat exhaustion. Be sure the routes you choose have plenty of water stop options. Maybe even tell a friend or family member details about the route and give them a ETA. ALWAYS carry your cell phone. Once again I encourage you to do your homework when it comes to hydration and heat related injuries. Now go ride Arkansas!
To see the previous post on hydration with Dr. Rankin click here.
Looking for a doctor who understands the athletes’ lifestyle? Check him out, click here.
Dr. Joshua Rankin
FirstCare Family Doctors – Tontitown, a MANA Clinic
171 N. Maestri Rd.
Springdale, AR 72762
479-361-1020
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