BOSTON — I like working out at the gym. But I’m 49 years old. I’m recovering from plantar fasciitis. The outside of my knee sometimes hurts when I walk up and down stairs.

So when I recently visited Ken Whittier, Boston University’s associate head strength and conditioning coach, at the Agganis Arena gym, he politely placed me in a different category than his professional and college hockey clients.

“No. No,” Whittier answered when I asked whether I should try any overcoming isometrics exercises — maximum-effort attempts to move immovable objects — during my next session at the YMCA. “I wouldn’t do it.”

This summer, Whittier is overseeing the programs of NHL players Noel Acciari, Matty Beniers, Connor Clifton, Matt Grzelcyk, Kevin Hayes, Charlie McAvoy, Evan Rodrigues, Zach Sanford and Will Smith. The BU men’s and women’s teams are also working out at Agganis.

They are training to be among the fastest, quickest, strongest and most durable hockey players in the world. I’d like to keep lifting my lawnmower out of my basement without tumbling down the stairs.

Attempting their movements, then, would not just misalign with my goals. It could be dangerous.

“Rule No. 1,” Whittier said, “is do no harm.”

Foundational work

A primary pitch of college hockey is the in-season training window. Players have all week to work out before they play on Friday and Saturday.

“You go to college, and you’re playing against 25- and 26-year-old guys on some of the teams,” said rising BU sophomore and Boston Bruins draft pick Jonathan Morello, who has gained approximately 12 pounds since the start of his freshman season. “I definitely wanted to get stronger, so I’m not pushed around in the corners as much. On top of that, want to keep working on my speed.”

Despite our divergences in age, body type and objectives, high-end hockey players like Morello and the general population can share some workout similarities. At the start of each summer, Whittier trains his players with base-level pillars in mind: strength, mobility, stability, fitness. This calls for movements that regular gym attendees do too, such as squats, deadlifts, bench presses and chin-ups. Whittier uses a four-day split: upper body on Monday and Thursday, lower body on Tuesday and Friday. Wednesday is a recovery day. Warmups are mandatory.

As for movements in the introductory three-week segment, which Whittier calls Phase 1, he wants them performed slow and steady at lower weights. An explosive lift in the first week is asking for an injury.

“It’s a remodeling phase,” said Whittier. “You can’t remodel muscles, soft tissue structures, tendon structures, ligament structures doing dynamic work first. You need to go slow and controlled. If you go straight to explosive, you don’t have enough requisite strength to be able to sustain that.”

For upper body, Whittier likes movements that work different angles to promote symmetrical strength. For example, players should do vertical shoulder presses to complement horizontal bench presses, vertical chin-ups to accompany horizontal cable rows.

For lower body, Whittier separates his lifts into hip- and knee-dominant movements: deadlifts for the former, squats for the latter. He prefers single-leg split squats over the traditional two-leg back squat to reduce lower back strain. In fact, the general population may be better designed than hockey players, who spend all season leaning forward, to perform back squats because of the latter’s on-ice stance.

Phase 2, the summer’s second three-week window, centers on strength. So far, this sounds reasonable for standard gym goers, but consider one wrinkle of Whittier’s split squats: tempo lifting.

Performance coaches promote time under tension, or how long a muscle is stressed during a movement. In certain phases, longer is better.

“The idea behind time under tension,” Whittier said, “is you’re fatiguing your muscles to create a lot of fatigue byproduct in your legs to signal to your body that we need to respond to this fatigue to handle it. So you get a great growth hormone stimulus with lower loads.”

For some of his players, Whittier prescribes split squats with a one-minute hold at the bottom of the movement. By the third week, they should progress to a three-minute hold.

I think normal split squats are murder on their own. I would rather light my glutes on fire than hold one for three minutes.

At BU, that’s just getting started.

‘Then we can have fun’

By Phases 3, 4 and 5, players have built the bases required to pursue power and speed.

“Then we can have fun,” Whittier said with a smile. “More advanced is the best way to say it. You have to think in continuums. One way the offseason program advances is general to specific. Or simple to complicated. Or non-competitive to competitive.”

In Phase 3, Whittier focuses on sprinting: timed 15-yard sprints, sled sprints, chase sprints. There’s one using a device called the 1080 Sprint.

The 1080 Sprint is a box with more than 100 yards of coiled cord inside. The cord provides resistance for sprinting, which a player would do while wearing a harness. Each sprint can be programmed for customization: a light load for the out part of the sprint, for example, and a heavy load for the return journey for a player who needs to work on deceleration.

At the same time, the 1080 Sprint measures metrics such as speed and distance traveled. This promotes competition. If one player hits a certain speed, the next player cannot help but try to best a teammate.

“When you’re able to train in close to maximal speeds, you should get faster,” said Whittier. “There’s a lot of exercises where I don’t think athletes get faster, quasi-speed/power exercises where they’re doing the roadrunner-type training. They’re moving their legs fast. But are you putting force into the ground? Is your body moving fast? Sprints are the best example of that.”

The next 1080 Sprint I see at the gym will be the first. Same goes for the flywheel machines Whittier likes his players to use.

In this setup, players wear harnesses and perform squats. The harder they push concentrically on the way up, the flywheel generates more eccentric resistance on the way down. This helps players improve at braking, which should make them more efficient at on-ice stops and starts. It also promotes improvement at their rate of force development, or how quickly they can perform an action. For you and me, deceleration is not as much of a priority as it is for a forward streaking for the far post at maximum speed and slamming on the brakes to await a pass.

“Probably a risk of injury. And it’s expensive,” Whittier said of why mainstream gyms do not have flywheels. “The deceleration demands for hockey are much, much higher than for a general population person.”

Some of Whittier’s more complex concepts do not require expensive equipment. In fact, you don’t need anything to execute some overcoming isometrics.

To demonstrate, Whittier pushed against a wall of the Agganis gym as hard as he could for five seconds. He would then follow the push with an explosive movement. This is the concept of “potentiation.”

Athletes prime their nervous systems to maximize output with a short but intense effort such as an immovable deadlift. They would then do a jump squat.

Another example would be pulling an immovable bar upward against rack pins while in a split position, then followed by a split-squat jump. The initial overcoming isometric sets up the athlete for optimal performance on the subsequent movement.

“Think of it as a dimmer switch,” Whittier said. “When I want to go to sleep, I want to turn my nervous system down. When I want to perform, I’ve got to rev it up. That’s why guys take caffeine. That’s why they do certain things that pump them up, like loud music. It’s a way to turn the dimmer switch up, potentiate your nervous system. That’s the fancy word, potentiation. Potentiation is going to make you more receptive to max outputs and improvements within whatever you’re trying to improve. You’re turning up the dial.”

I asked Whittier why more normal folks don’t try overcoming isometrics. Pushing against a wall seems not just straightforward but safe. He agreed. But he also noted that for most people, pulling an immovable bar against rack pins would not feel good. For his clients, these are Phase 3, 4 and 5 movements, targeted for elite athletes chasing speed and power. You and I could pursue the same goals, but that comes with risk.

“I think you should see more speed and power work at Planet Fitness,” said Whittier. “But inherently, because it’s the riskiest, it’s not safe for training.”

For us, Whittier prescribes the following: two lower-body days (hip- and knee-dominant movements), two upper-body days (push and pull) and two days for core, plus cardiovascular conditioning. This could be a 45-minute daily session. People with less free time could lift for 30 minutes one day, then do a 30-minute cardio workout the following day, alternating through the week.

“You can stay in the Phase 1 (and) 2 world with general population forever,” said Whittier. “You don’t ever have to do a one-rep maximum with a general population client. But as long as you’re staying within five to 10 reps, that’s a good window to stay in. That’s going to keep your bone density up. It’s going to keep mobility, health and your body feeling good.”

That sounds pretty good to me. I’ll leave the hard stuff to the players.