“Help! Help! Help!’’

The single request rang out repeatedly in the North Reading High gymnasium Tuesday night as the girls’ basketball team worked through its practice session.

The players were in the midst of a halfcourt scrimmage, the teams distinguished by green and white team pinnies.

As point guard Carly Swartz ran through plays, one constant remained: strong help defense.

Though Swartz and 6-foot-5 center Jess Lezon connected for scores in the paint occasionally, the guard pairing of senior Julia McDonald and junior Kat Hassapis never made it easy. With smooth, agile slides, the two defenders were all over the floor, denying passing lanes and closing out shot attempts with impressive execution.

Defense and energy are paramount.

“A lot of the girls on this team, we’ve played together since like the fourth grade,’’ McDonald said.

“Even ever since we were little we’ve had this dynamic of different specialties. We just always worked especially on defense. Our teammates feed into it.’’

McDonald and Hassapis, in particular, are indispensable assets on a 18-2 North Reading squad that is primed for a deep run in the Division 3 tourneament.

Their dedication to defense and ability to lock down opposing teams’ top scorers elevates the energy level of the rest of their teammates.

Their effort is inspiring.

Coach Bob Melillo pointed to a mid-December matchup against Cape Ann League rival Masconomet Regional. North Reading prevailed, despite 26 points from Masco junior guard Grace Fahey. For the rematch in January, determined to see a better defensive performance, he called upon Hassaspis.

Fahey finish with just 3 points, all free throws. Meanwhile, McDonald shut down Paige Amyouny, an emerging sophomore guard.

“It was a game we knew we had to get to stay in the conference championship hunt,’’ Hassapis said.

“Our offense has a lot of key scorers, so [Julia and I] knew if we focused on shutting our players down, the rest would come.’’

Lezon (17.5 points per game) and Swartz (12) lead the way offensively, but they appreciate the important defensive presence that Hassapis and McDonald deliver at the other end of the court.

“Our transition game is the best aspect of our offense, so when they can make key plays on defense, it allows us to turn around and push the ball and score easier,’’ Swartz said.

“There’s been so many games I could point to where Kat and Julia have stepped up and held their best players to low scoring, and every time,its so beneficial to our victories.’’

At Bishop Fenwick, senior Ellen Fantozzi excelled as a defender for the girls’ soccer team that registered 11 shutouts last fall. This winter on the court, her dedication to lockdown D continues.

“As a sweeper, I’m the last possible defender, so I have to to keep everything in front of me and contain the ball,’’ said Fantozzi, a captain who plays an integral role in the backcourt for a 17-4 squad.

“With basketball it’s the same thing. If you can’t get by me, you won’t score.’’

Coach Adam DeBaggis said Fantozzi is “like a director out there.’’

“In the huddle she’s talking as much as I am, and in games she always talking to make sure everyone is on the same page. You see the teams that don’t do that have a lot more trouble playing defense.’’

And this season, Fantozzi has taken on a protégé in freshman guard Jaxson Nadeau , whose ability is commanding the respect of her teammates.

“I know the people around me are relying on me to make the stops and force turnovers,’’ Nadeau said.

“It’s almost like the team’s energy is right in your hands. When I follow through, the team can feed off of it.’’

Revere High girls’ coach Dianna Finn has a collection of young talent.

In the paint, sophomore center Valentina Pepic is averaging just under 20 points per game with a combination of strength and quickness . At the point, sophomore Pamela Gonzalez is averaging 11 points per game.

Yet, it is senior forward Marissa Scott that sets the tone for the 17-4 Patriots.

“Marissa isn’t the most offensive-minded out there, but her importance to the team is clear when you watch her play,’’ Finn said.

“Her aggressiveness and instincts on defense inspires her teammates to keep a consistent level of intensity.’’

Scott transferred to Revere from Salem High after her sophomore year. But, she had played previously with the majority of her new teammates in the offseason, so developing chemistry was not an issue.

“I’ve known these girls for a while, so I know their game and what gets them going,’’ Scott said.

“I can see when they’re getting down on themselves. The negativity of even just one player can really mess with the team energy as a whole, so I do my best to keep everyone inspired and focused on the goal ahead.’’

And her energy clearly starts at one end of the court.

“I’ll have my good days offensively, but defense is something I can always count on,’’ Scott said.

Ethan Schroeder can be reached at ethan.schroeder@globe.com.