The look on their faces speaks volumes of the painstaking lengths they're willing to put their bodies through.
Upon first glance, the grunts and grimaces that echo with each stretch may make them appear as though they're a glutton for punishment.
But, in the end, the high intensity workout they receive is well worth the buckets of sweat that drip off their foreheads and down their bodies.
Complete with push ups, sit ups, squats, burpees, sprints, kettle bells, and plenty of sweat, the Kettlebell Conditioning Class is a real sight to behold.
The workout enables participants to burn fat, gain strength, tone their whole body and increase cardiovascular endurance.
Sponsored by the Palmerton Fitness Center, the class is taught outdoors in the borough park by instructor Jake Dempsey.
Dempsey, an avid exercise buff, said the class is chock-full of health benefits.
"People seem to like it better than the old box aerobics," Dempsey said. "What's nice about it is you're not trying to challenge the person next to you, but you're trying to challenge yourself."
One could sympathize with Bob Perry, 60, of Palmerton, after he concluded the strenuous workout.
"I challenge anybody who thinks they're in good shape to try this," Perry said. "We have a great instructor, and it's one of the high points of my week."
Audrey Beidleman, 59, of Lehighton, is well satisfied with the program.
"It's all about conditioning," Beidleman said. "Anybody can do it."
Barb Brader, 48, of Palmerton, said the time flies thanks to Dempsey's exercise regiment.
"It goes fast," Brader said. "He (Dempsey) switches it up so that it's always something different."
As of May 11, the classes will be held at 6:15 p.m. Tuesdays and Thursdays, and at 11 a.m. Saturdays.
Pre-registration is required. Stop in at the center, or call 610-826-2300 for more information.