"I'm not surprised," Gentile said. "[Police officers] are under tremendous stress. They're always on guard, they work long hours and sometimes in dangerous areas."
Gentile said daily stress causes some officers to tense their back and neck, which causes upper back pain and headaches.
"There is definitely a physiological manifestation of the psychological stress," Gentile said.
So why do police officers such as Best submit themselves to daily strains and sprains that eventually may turn to deep aches and pains?
"In only one year, I can recall so many times I've served my community," Best said, "and that outweighs the pain."
While we might assume their name explains it all, firefighters suffer pain beyond just fighting fire.
Firefighters undergo exposure to extreme heat. At times, their proximity to heat can burn them, even if they haven't touched the fire at all.
But burns are not their only cause for pain, said Robert Hayden, spokesman for the American Chiropractic Association.
In the midst of battling flames, firefighters are exposed to intense shoulder and lower back stress as they resist powerful water pressure shooting through the large and heavy hoses they lift. They climb up and down ladders and through windows strapped to a 25-pound breathing tank -- sometimes while carrying a person to safety.
"I've seen firefighters forced to retire after falling through floors or the roof to the level below," Hayden said. "They have to balance on unstable ground while carrying so much."
While police officers incur more physical injuries, Hayden said firefighters endure deeper pain by heavier lifting.
Firefighters' rigorous shift hours add further physical stress. On an overnight or two-day shift, firefighters often sleep at fire stations where the mattresses or cots that are available may not provide adequate back support.
"It's far from comfortable, but these guys are warriors," Hayden said. "They have to call on their bodies to do anything at any given time."
Long drives behind the wheel of a heavy truck made the pain in Duane Strating's legs unbearable.
Fifteen years ago, Strating had spinal disc surgery to relieve the nerve pressure causing his leg pain. But now driving trucks has taken a toll on his back and neck.
Strating, who owns a car hauling company, said the pain is not only due to the constant vibrations and bouncing his body experiences when driving, but also from heavy lifting and pulling he is required to do to prepare his transport.
Although David Paris, his chiropractor, recommends exercise, Strating said it is difficult on days when he is driving his truck.
"It is easier to pull over on the side of the road when you're driving a car and stretch," Strating said. "There are not as many places for trucks to pull over."
Paris said the most physical stress on truck drivers comes from driving through mountainous areas as they maneuver curves and pull their truckload uphill.
"[Truck drivers] are in a unique situation wherein they take on the highest pressures in the back via sitting, often unsupported, then may get out and lift and load, without warm-up in varying weather conditions," Paris said. "Depending on what they are hauling this can be very strenuous."