The leg press machine is a fixture in most fitness facilities, providing a structured way to strengthen the muscles of the lower body. Users often load plates onto the sled, but the machine presents a challenge even before any external weight is added. The inherent resistance of the foot platform and its carriage is known as the “starting weight.” This baseline resistance is important for accurately tracking strength progress and ensuring safe training loads. Understanding this initial resistance is the first step in properly programming a leg workout.
The Source of Unloaded Resistance
The starting resistance felt on a leg press machine originates from the physical mass of the moving components, primarily the sled and its carriage mechanism. For the common 45-degree incline press, the user must push the sled’s physical weight against the force of gravity. Since the sled moves along an angled track, the effective resistance is a fraction of the sled’s total mass, determined by the machine’s angle.
The resistance on a horizontal leg press, which uses a weight stack and cable system, is slightly different. Here, the starting resistance comes from the footplate mechanism and the tension of the cables, often resulting in a much lower initial load. Regardless of the machine type, the inherent weight of the sled or foot carriage is the mechanical reason a user must exert force without plates being loaded.
Common Starting Weights by Machine Design
The specific amount of unloaded resistance varies significantly depending on the machine’s design. The 45-degree incline leg press, which is plate-loaded, tends to have a much higher starting weight because its heavier construction is necessary to handle the massive external loads users often place on it. Typical unloaded starting weights for a 45-degree press range from approximately 75 pounds to 125 pounds.
Due to the 45-degree angle, a 100-pound sled only requires about 70.7 pounds of force to move, which is the actual resistance the user feels. Horizontal leg press machines, which are often selectorized and use a weight stack with cables, present a much lower starting resistance, typically between 10 and 20 pounds. Vertical leg press machines, which are less common, may have an unloaded resistance closer to 50 to 80 pounds, as they move the weight directly against gravity.
Variables That Affect the True Resistance
Even when the manufacturer’s stated sled weight is known, the actual resistance a user feels can be modified by operational variables inherent to the machine’s condition. The most significant factor is the coefficient of friction, generated by the sled’s rollers, bearings, and the rails it travels along. A machine that is poorly maintained or has worn parts will generate higher friction, which the user must overcome in addition to the sled’s gravitational load. This added resistance can make the movement feel substantially heavier than the calculated weight suggests, especially during the initial push.
The machine’s angle also plays a role, particularly for the 45-degree press, as the effective weight is determined by the sine of the angle multiplied by the total mass.
Locating the Specific Weight of Your Machine
To accurately determine the precise starting weight of a specific leg press, the most reliable method is to consult the equipment manufacturer. Many commercial-grade leg press machines have the unloaded sled weight listed directly on a sticker or a small plaque attached to the frame. This label provides the most accurate baseline figure for that particular model.
If a label is not present, gym staff or a certified personal trainer may have access to the equipment manual or a database containing the specifications. Alternatively, users can find the information by searching online using the machine’s brand name and model number, which is typically printed on the frame or seat.