The Biomechanics of Resistance Apparatus

Posted by Spenser Hicks on



Gyms these days are packed with countless types of resistance machines and it is very important to understand the differences among them. The majority of them use gravitational forces, however, there are some that incorporate elastic, hydraulic, or pneumatic resistance. Each type of machine has its own biomechanical properties. It is crucial to understand that some of them are poorly designed resulting in a higher risk of injury. Proper selection of the type of resistance will make your workouts more effective as well as safer. Each of the aforementioned resistances will be discussed.



Using dumbbells in your workout is a good choice and this is why. Their resistance is caused by earth’s gravitational forces and it is always in a downward direction. They allow for full range of motion and there is an increased transfer to real world movements (Wilkins, 2010). Free weights allow you to work in a more functional environment and when done properly you are able to create the proper balance throughout your musculoskeletal system. You are able to recruit more stabilizing muscles since you are required to control the weight through multiple plans of motions. If you compare the electromyographic activity of a free weight squat to a smith machine squat the differences are noticeable. Studies have shown that there is a significantly higher electromyographic activity in the gastrocnemius, biceps femoris, and vastus medialis during a free weight squat versus a Smith machine squat (Schwanbeck, Chilibeck, & Binsted, 2009).  This indicates that free weights are more effective and translate better to daily activities such as getting out of a seated position, grabbing something off the ground, and countless others movements you do throughout the day.


Now don’t get me wrong not all machines are bad. Seated pulldowns, seated cable rows, and other hammer strength type exercises are still viable choices. The machines that have separate arms allow you to have an equal amount of resistance on each side. This results in a balance of muscular adaptations as you are not able to favor one side over the other. It is not unusual to have one side of your body being stronger than the other. If this is the case for you, focus on using equipment that will allow you to equalize both sides of your body. However, if you are new to the gym and consider yourself a beginner don’t think that you are forced to jump right into free weights unless you are confident in your form and technique. Machines can effectively ease you into free weights as long you are recruiting the right muscles. Ask for help from a friend or a trainer and don’t feel the need to go at someone else’s pace. You want to progress in a safe and effective manner.



Like any hydraulic system, there is a hydraulic ram that forces fluid through a small aperture and therefore creates resistance. Resistance machines that have this type of system provide only a concentric phase. This is quite popular in special populations due to the reduced amount of soreness by having no eccentric phase (Brown, 2008). Hydraulic machines are safe and easy to use but it is necessary to have an eccentric phase in your exercise. The eccentric phase causes muscle break down while your muscle lengthens under a load. During your squats for example, really focus on your glutes and hamstrings as you lower your body. If you are feeling a balance between the muscles on the front of your legs and those on the back of your legs then you are reinforcing good neuromuscular control.



The use of elastic bands is quite popular in the fitness world. They are very easy to use and are not intimidating at all. You can add resistance to your exercises in a simple and effective way. However, when using an elastic band, the resistance during the extension phase is lower than during the flexion phase (Wilkins, 2010). The resistance is greater the more you stretch the band. They are a great option to add while performing squats as you can functionally work your abductors. Elastic bands are a great for beginners but they are limited to their max resistance. You can get more resistance from using free weights or other resistance machines.



Pneumatic systems use air pressure to create resistance. Such machines provide both a concentric and eccentric phase (Brown, 2008). The higher the pressure is in the system the more resistance is supplied for the exercise. They are similar to the hydraulic system but the pneumatic system is advantageous since there is an eccentric phase. These types of machines are more geared towards physical therapy and older populations.


It is necessary to understand that the ideal weight training programs consists of a variety of resistance machines. You want to challenge your system in a safe and effective way without creating imbalances throughout your muscles. Perform exercises that are within your capabilities and focus on which muscles should do the moving. If you are not going to perform each repetition correctly, your brain will remember those imbalanced muscle patterns which can increase your chances of having complications down the road. Developing a balanced system takes time as you may be correcting a muscle pattern that you have reinforced for years. If needed seek guidance from a certified professional if you think you are doing something wrong.




Brown, T. J. (2008). Conditioning for Strength and Human Performance. Philadelphia: Wolters Kluwer.

Schwanbeck, S., Chilibeck, P. D., & Binsted, G. (2009). A Comparison of Free Weight Squat to Smith Machine Squat Using Electromyography. Journal of Strength & Conditioning Research , 2588-2591.

Wilkins, L. W. (2010). ACSM's Resources for the Personal Trainer 3rd Ed. Philadelphia: Wolters Kluwer.



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