Longer days, beach trips, and oh yea… do not forget the increased temperatures that will be around for the next few months.
We are going to dive into increased heat exposure and how It affects your body (physiology) and how you can expect this to change or possibly alter your workouts. This blog is coming from a CrossFit facility, but it really does not matter what you are doing, whether you are playing a round of golf or going on a run, you have to listen to your body.
Basics from below:
- Use your common sense, if you feel like you need a break, take it.
- Hydrate well before and during exercise.
- Your age minus 220 will allow you to estimate your maximum cardiac rate.
- Your body will regulate your body temperature through sweating during exercise.
- Just because it is hot does not mean you cannot workout, but it does mean that sometimes you will need to lower your intensity and exposure.
Tips to get the most out of your summer training:
- Try to workout at your normal time, if you do not normally train at 2pm, do not start that during the summer.
- Hydrate before and have cold water with you while you workout.
- Know your body, if you know you do not respond well to heat, do not test it, try to find a class early AM or late PM, that dodges some of the increased heat.
- If you did not properly fuel pre workout, it is probably best to push training off to a later session.
- Lower your normal pace “intensity” by training at a sub maximal threshold early in the summer months as your body gets acclimated to the heat. (If you normally run a 7:00 mile in an ideal setting, you would be wise to back that down to an 8:00 mile pace as temperatures increase and your body adjusts. This in CrossFit could look like lowering sets of wall balls form 20 every 45 secs to 10 every 30 secs.
- Bring water with you and drink it.
- Seriously, hydrate.
NERD ALERT: Geek out below on some science.
Cardiac output = the volume of blood pumped per minute by each ventricle. The average cardiac rate for an adult is 70 beats per minute; the average stroke volume (volume of blood pumped per ventricle per beat by each ventricle is 70-80ml per beat. The product of these two variables gives us an average cardiac output of 5,500ml/min (5.5L/min) (Fox, 2009)
How does your body respond to exercise:
Your body at “rest” will have a “cardiac output” of 5 L/min during exercise this could raise to 25L/min with vigorous exercise, this essentially means that you will have more blood pumping through your organs (skin, muscles, etc…) Why is this important? Your heart is working hard to pump increased amounts of blood through your body. So listen to it if it seems like you need a break.. take it!
This increased flow does not mean that you have more blood it just means that the rate of your blood moving through your body is increasing, 5x as fast; potentially 5 to 25L per minute. `
This increased flow is due to (primarily) to an increased cardiac rate: See table below for a “Relationship between Age and Average maximum cardiac rate”
- Age: 20-29 (190 beats/min)
- 30-39 (160 beats/min)
- 40-49 (150 beats/min)
- 50-59 (140 beats/min)
- 60+ (130 beats/min)
*Maximum cardiac rate can be estimated by subtracting your age from 220
This increased cardiac rate will allow an increased flow of oxygen to the exercising muscles; this is the major reason why you see (elite) professional athletes with higher V-O2 max
Cool side note: during heavy exercise 80-85% of your blood flow will go to your skeletal muscles. This is an increase from 15% at rest, so you can imagine since the blood is mostly flowing towards skeletal muscles you can assume that there is not a lot of blood left to go to your “gut”. kidneys, bones or brain… basically anything but your skeletal muscles.
Other Cool Side Note: Your body will regulate body temperature by sweating when too hot, or shivering when too cold. This Is your body’s attempt to find homeostasis during times of an external stimulus (temperature causing a change in core body temp). When this happens increased blood flow must shift from the muscles to the skin, which could hinder your ability to perform optimally.
Under normal conditions, your skin, blood vessels and perspiration level adjust to the heat. But these natural cooling systems may fail if you’re exposed to high temperatures and humidity for too long, you sweat heavily, and you don’t drink enough fluids.
The result may be a heat-related illness. Heat-related illnesses occur along a spectrum, starting out mild but worsening if left untreated. Heat illnesses include:
- Heat cramps. Heat cramps, sometimes called exercise-associated muscle cramps, are painful muscle contractions that can occur with exercise. Affected muscles may feel firm to the touch. You may feel muscle pain or spasms. Your body temperature may be normal.
- Heat syncope and exercise-associated collapse Heat syncope is a feeling of lightheadedness or fainting caused by high temperatures, often occurring after standing for a long period of time, or standing quickly after sitting for a long period of time. Exercise-associated collapse is feeling lightheaded or fainting immediately after exercising, and it can occur especially if you immediately stop running and stand after a race or a long run.
- Heat exhaustion. With heat exhaustion, your body temperature rises as high as 104 F (40 C), and you may experience nausea, vomiting, weakness, headache, fainting, sweating and cold, clammy skin. If left untreated, heat exhaustion can lead to heatstroke.
- Heatstroke. Heatstroke is a life-threatening emergency condition that occurs when your body temperature is greater than 104 F (40 C). Your skin may be dry from lack of sweat, or it may be moist.You may develop confusion, irritability, headache, heart rhythm problems, dizziness, fainting, nausea, vomiting, visual problems and fatigue. You need immediate medical attention to prevent brain damage, organ failure or even death.
Pay attention to warning signs
During hot-weather exercise, watch for signs and symptoms of heat-related illness. If you ignore these symptoms, your condition can worsen, resulting in a medical emergency. Signs and symptoms may include:
- Muscle cramps
- Nausea or vomiting
- Excessive sweating
- Dizziness or lightheadedness
- Low blood pressure
- Increased heart rate
- Visual problems
If you develop any of these symptoms, you must lower your body temperature and get hydrated right away. Stop exercising immediately and get out of the heat. If possible, have someone stay with you who can help monitor your condition.
Measuring core body temperature with a rectal thermometer is essential to accurately determine the degree of heat injury. An oral, ear or forehead thermometer doesn’t provide an accurate temperature reading for this purpose. In cases of heatstroke, due to confusion and mental status changes, you won’t be able to treat yourself and you’ll require emergency medical care. The most effective way of rapid cooling is immersion of your body in a cold- or ice-water tub.
In cases of heat exhaustion, remove extra clothing or sports equipment. Make sure you are around people who can help you and assist in your care. If possible, fan your body or wet down your body with cool water.
You may place cool, wet towels or ice packs on your neck, forehead and under your arms, spray yourself with water from a hose or shower, or sit in a tub filled with cold water. Drink fluids such as water or a sports drink. If you don’t feel better within about 20 minutes, seek emergency medical care.
All of the above was adopted from the Mayo Clinic: Link Here
Sources: Fox, Stuart. Human Physiology – 11th Edition, 2009