The Prime SmartCam: Why the Numbers Read 3, 5, 1, 4, 2

One green lever on Prime Fitness USA’s selectorized machines changes where every rep gets hardest. The numbers beside it look out of order. They are not. Here is how the SmartCam works and how to read the dial, explained on the Prime machines on our floor.

01Every machine has a strength curve

No exercise feels equally hard from start to finish. Your muscles produce more force in some joint positions than others, and a machine’s cam decides where its load peaks. On a conventional selectorized machine, that cam is fixed. You can move the pin, but you cannot move where the hardest part of the rep lands.

Prime spec Prime Fitness USA calls its answer SmartStrength. On its selectorized machines, Prime says its patented SmartCam “allows the user to move the peak resistance throughout the range of motion with a simple lever adjustment.”

The lever does not add or remove weight. The stack stays the same. What changes is where in the rep that weight hits hardest.

02The five settings

Prime spec Every Prime Hybrid and Evolution product page we checked lists the same five SmartStrength settings:

Sources: Prime Fitness USA product pages, “Find Strength In Numbers” (2016) and “LIFTOFF” (2017).

03Read the dial left to right

Look at the dial on one of our SmartCams and the numbers run 3, 5, 1, 4, 2 along the arc. Most people assume that is random. Line it up with Prime’s definitions and a pattern appears.

On our floor The order along the arc is 3, 5, 1, 4, 2, confirmed on two of our machines.

Our interpretation Read left to right, the dial runs from the beginning of the rep to the end: stretch, stretch plus middle, middle, middle plus squeeze, squeeze. Prime does not describe the layout this way, but its own setting definitions line up with it exactly. Once you see it, you can read any SmartCam on the floor without a chart.

04Big numbers, small numbers

There is a second detail most people walk past. The numbers are not all printed the same size.

The dial and full machine on our Prime pec / rear delt. On our floor

05How a cam changes the load

Our interpretation A cam is a wheel that is not round. The cable or belt from the weight stack wraps around it, and the distance from the cam’s axle to where the cable leaves it (its effective radius) changes as the cam turns. Where that radius is longer, the stack has more leverage against you and the rep feels heavier. Where it is shorter, the rep feels lighter.

A conventional machine has one fixed cam, so its heavy point never moves. Prime’s lever changes the SmartCam’s setting so the long-radius section lines up with a different part of your rep.

The general principle behind any cam. Prime does not publish the SmartCam’s internal geometry or force curves, so this shows the idea, not Prime’s design or measured values. Our interpretation

06Same pin, different set

Because the cam changes leverage, the same pin weight will feel different on every setting. That is the point. One machine, one seat, one stack, and five different strength curves to train against.

• Want the stretch loaded? Setting 3 puts the peak at the start of the rep, where the muscle is longest.
• Chasing the squeeze? Setting 2 builds toward the end, where the muscle is shortest.
• Learning the machine? Setting 1 behaves like the conventional equipment you already know.
• Want the load spread out? Settings 4 and 5 blend two regions instead of peaking in one.

07How to use it on the floor

1. Set up the machine first. Seat, pads and starting position, the same as any selectorized machine.
2. Learn the movement on setting 1. It behaves like a standard machine, so it is the right place to learn the path.
3. Set the cam, then the pin. Decide which part of the rep you want to train, then choose the weight for that setting.
4. Change the cam between sets, with the stack at rest. Never move the lever mid-set or with the stack lifted.
5. Expect the pin to move. 100 on setting 3 is not 100 on setting 2. Adjust instead of forcing the number.
6. Log both, every set. Write “Cam 3 / 100,” not just “100.” Without the cam setting, the log does not tell you what you did.
7. On a two-cam machine, check both sides. Our pec / rear delt has a cam on each arm. Make sure each one is where you expect before you start.

08What the SmartCam does not tell you

The system is genuinely useful, and it is also worth being clear about its limits.

• Prime does not publish force curves, so nobody outside Prime can say exactly how much heavier setting 3 is at the start than setting 1. We make no numerical claim.
• No peer-reviewed study has tested SmartCam settings directly.
• Related research looks at range of motion, not cams. A 2023 meta-analysis (Wolf et al.) reported a possible but uncertain hypertrophy benefit from training at long muscle lengths compared with full range. That is context for why lifters care about the stretch, not proof that setting 3 builds more muscle.
• Prime’s marketing says SmartStrength yields more muscle fibre recruitment “from origin to insertion.” We have found no independent evidence for that claim, so we do not repeat it as fact.

What is clear is the mechanism. The lever changes where the cam’s leverage peaks, and that gives a lifter a real, repeatable choice on every set.

09The Brickhouse perspective

A conventional selectorized machine gives you one resistance curve. The Prime machines on our floor give you five, and the choice is a lever away. That is the kind of equipment we look for at Brickhouse: machines that reward lifters who understand what they are doing.

The same idea runs through Prime’s plate-loaded line, where a three-peg Torque Arm does the job the SmartCam does here. Learn one system and you can use the other.