Hydraulic Exercise Equipment Versus Stacked Weight

The main objective of any fitness center is to offer a variety of exercise equipment. When you use different types of resistance, your workouts remain fresh and effective. Two types of resistance equipment you encounter at health clubs are hydraulic and stacked-weight machines. The two are very different, from looks and weight amounts to the way your muscles are stimulated.

  1. Take a Peek

    • Your first glance at a resistance exercise machine lets you know what type it is. A hydraulic machine and a weight-stack machine look similar in the seats and handles. For example, a chest press machine has a seat, a back rest and handles that extend outward from the chest. You can tell a weight-stack machine by its square weight plates stacked upon each other in a tower. The cables of the machine are attached to the top plate and you adjust the pin to select the number of plates you want to lift. Identify a hydraulic machine by the fluid-filled cylinders that are connected to the moveable parts of the machines.

    Read the Label

    • The weight plates on the towers of weight stacks typically weigh 10 to 20 pounds each. The plates are labeled in increasing amounts, so you can quickly identify how much weight you lift. When you place the adjustable pin in the center of the plate to connect to the guide rail, you choose whether you want to lift 10, 20, 30 or more pounds. In comparison, hydraulic equipment does not have labeled weight amounts. Hydraulic resistance is dependent on the user. The faster and more forcefully you push and pull against the fluid-filled resistance, the higher level of resistance you generate. If you push and pull slowly and with little effort, your resistance level is less.

    A Material World

    • The weight plates on a weight stack are made of metal. They evolved from free-weight plates that slide onto the ends of barbells. Machines used to use the circular plates as resistance until the weight stacks were developed to quickly transition from one amount of resistance to the next. Hydraulic resistance is provided by oil inside of a cylinder. The speed at which you push and pull the levers changes how fast the fluid flows. It's similar to swimming against a current, which is more difficult the faster the current flows.

    Push It

    • When you perform exercises on a machine that has a weight stack, your muscles contract concentrically during the hardest part of the movement -- when you raise the weights against gravity. As you lower the weights, your muscles contract eccentrically so the weights simply do not fall back into place. With hydraulic resistance, your muscles perform only the concentric phase of the exercise. When you release the chest press, for example, the fluid flows easily to one side of the tube in preparation for your next push against the fluid resistance.

    Two Thumbs Up

    • Both types of resistance equipment have their benefits. The "Journal of Strength and Conditioning Research" reports the results of a study using hydraulic resistance during circuit training. The subjects showed heart rate responses similar to circuit training performed with traditional weight equipment. Although weight-stack machines are more common in most health clubs, hydraulic machines can be found, especially at facilities that are women-only centers.