Celtics chief medical officer Brian P. McKeon attributed Rondo’s heroics to the “fight or flight” response, and the endorphins “that help us achieve tremendous things in pain.”

But even in less dramatic circumstances, he said, “part of what makes an athlete an athlete is the ability to play through pain.”

McKeon, an orthopedic surgeon and head team physician, pointed to a recent study from the University of Heidelberg, published in the June issue of the scientific journal Pain, that supports this theory. German researchers reviewed 15 studies that included more than 550 athletes and 330 people with normal activity levels, and found that while most people had the same threshold for pain, athletes had a consistently higher tolerance.

The example set by stars such as Rondo trickles down to amateurs and children, but while soreness and muscle ache are part of athletics, playing through serious pain is never a good idea, said William Levine, an orthopedic surgeon, head team physician at Columbia University, and chairman of the steering committee for STOP Sports Injuries, a national campaign urging awareness of sports overuse and traumatic injuries in children. “Certainly not for student athletes, not for weekend warriors,” he said. “Even in professional sports, it’s almost never a good idea.”

The cultural message to play through pain is strong, said Dr. Samantha O’Connell, a clinical psychologist in Quincy who specializes in treating athletes and coauthor of a review of research on playing through pain, published in July in Current Psychiatry. It’s not just the professionals who have a championship or a contract at stake who feel the pressure, but high school, collegiate, and even recreational athletes. At every level, she said, persevering and “toughing it out” are part of the sports identity.

It takes about 15 minutes at the athletic trainer’s office in the field house at Marciano Stadium in Brockton to see that even at the high school level, the athletes are regularly playing with or rehabbing from some form of physical pain.

Jeri Connor, athletic trainer for Brockton High School’s sports teams, works at a fever pitch, taping wrists, thumbs, and calves of football, soccer, and volleyball players before they go to the day’s practice. She prescribes stretching exercises to two girls from the soccer team who rehab in her office with Thera-bands, while trying to evaluate the new injuries in students who form a long line at her door.

High school athletes, especially freshmen, can’t always distinguish between the everyday soreness from workouts and practice and serious injury, Connor says.

One freshman football player complains to Connor that his shoulder hurts. When she gives him a series of strength tests, he can easily resist just about any pressure she puts on his arms in any direction. After making sure his shoulder pads fit property, she sends him back to practice, but with no contact drills. “A minor bruise from hitting drills yesterday,” she deduces.

Meanwhile, another freshman, a running back, arrives with knee pain from the previous week’s practice that he describes as an “8 on a scale of 1 to 10.” He jumps when she touches his knee and admits to playing Monday’s game while in that high level of pain.

As she tests his knee to rule out ligament damage, she admonishes him. “If I can’t touch you without you jumping, do you think one of your friends is going to care where he hits you?”

She determines the knee injury is a bruise of the fat pad underneath the tendon, puts him on a treatment table with an ice pack, and tells him he can’t practice or play until she gives him the OK.

Connor, who has been the athletic trainer at Brockton for 20 years, says that for the most part, coaches listen to her recommendations and understand that putting an injured athlete back into the game too early and allowing an injury to worsen is “shooting themselves in the foot.”

But there will always be student athletes who try to hide their injuries and play anyway, she adds. It’s the nature of an athlete to want to compete.

But the pressure also comes from teammates, and too often, it comes from parents.