As professional drivers, we're required to stop every 3 hours or 150 miles (whichever comes first) and 2 hours/100 miles if placarded with Haz-Mat. This is in order to check our vehicles for cargo securement and to look over our vehicles, especially the tires. The 2 hour time frame is better as that's about the maximum amount of time that our leg muscles can really handle sitting still while in a vertical position. Doctors have determined that our blood will pool up in the leg veins during long periods of sitting still and can clot due to the lack of muscle contraction that normally pumps the blood out of the legs and back to the heart during activity. 
This is called "Deep Vein Thrombosis" or DVT.
With DVT, clots will form and it's possible that they will grow and a portion could break off and travel through the leg and abdominal veins back to the heart causing death. Studies have shown that people who were older, had cancer, heart problems or other serious illnesses were likely to suffer from this fatal condition if they didn't take the preventative measures.
Every year, 2 million people get DVT and up to 200,000 of them die. According to an article that I read on WebMD.com, DVT kills more people every year than AIDS, breast cancer and vehicle accidents combined.
What can we do?
- Stop every 2 to 3 hours and stretch and walk around. Check out the 9 best stretches below.
- Drink plenty of water; this helps circulation and will cause you to stop and take a break.
- Wear compression socks. Swiftwick is actively marketing to the trucking
industry and I have a few pair of their quality products. Click here to go to their website.
- If it's safe to do so and you're on cruise control, simply do some calf raises from the driver's seat. Keep your toes on the floor and raise your heels. This will contract your calf muscles and lower quads just above your knees. It's not as good as full movement, but will help.
Other exercises that you can do behind the wheel if safe to do so:
- With both hands on the steering wheel, squeeze as hard as you can and hold it for about 5 seconds. Do 5 to 10 reps of this. This exercise will contract every muscle in your finger, hands and arms. Just don't contract any muscles in the neck as this will cause you to get dizzy.
- In cruise control, with feet flat- raise them about 3-4" off the floor for about 10 repetitions. You can quickly get in 3 sets. This will get the blood flowing through the abdominal region.
The extra time it takes to get to your destination is time well spent because it's for your health.
A special thanks to Derek McClain over at TheHealthyTrucker.net for the use of these images!