Heavy regimen for fitness fanatics

“Next station!” yelled Will Harris, trainer at the Riverdale Strength and Fitness Club.

Claire Guilette, a pregnant 34-year-old, picked up a sledgehammer and started pounding on a monster-truck tire. On the other side of the tire Gary Axelbank, 56, jumped in the air, landed on it, then jumped backward to the ground. Jeanne Chartier, 64, removed a harness attached to a tire filled with weights and walked over to an 80-pound beer keg filled with water. She picked it up and walked it across the gym. Samantha Sherwood, 24, put on the abandoned harness and dragged the tire across the gym floor.

Around the room, others rowed, jumped rope, lifted sandbags or kettleballs.

Mr. Harris checked his stopwatch. Time’s up.

“Next station! Next station!”

The sweaty and exhausted members of the club moved on to their next stations. Each of them wore a black shirt that read “Train, Dominate, Repeat.” The cement walls at 130 Gale Place had inspirational sayings and words of encouragement written on them, like “Life’s Short. Lift Heavy” and “No Dying Allowed.” It was hot and muggy. Heavy metal blared through the sound system and someone groaned, as if following the music.

“Nothing we do around here is crazy,” Mr. Harris said.

Mr. Harris, 24, is a personal trainer. He opened the gym a little more than a year ago and it’s not glamorous. It looks like a basement, even though it’s in the middle of the building, halfway up the long staircase connecting the bottom of Van Cortlandt Park South and Gale Place, one of the Amalgamated Houses. By word of mouth, the gym has grown to about 40 members ranging in age from 14 to 66. Two weeks ago, the gym became affiliated with the worldwide association CrossFit, a fitness community that stresses overall strength fitness without the use of many typical fitness machines.

The program serves different purposes for different members. Ms. Guilette started coming to get in shape for her wedding. Mr. Axelbank, the host of the TV show BronxTalk on BronxNet, said he does it to be a more efficient human being. Others come to train for sports or even jobs — there are police officers among them. One thing that everyone said, even when they were covered in sweat and in agonizing pain, was how much fun the regimen is.