Barbell vs System Velocity

Despite the proposed benefits of velocity-based training (VBT), it is important that strength and conditioning practitioners understand the differences between different types of velocity and its applications for training athletes.

By Dr. Tim Suchomel

Velocity based training for youth athlete assessment

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Introduction

The use of VBT in resistance training programs has grown considerably over the last decade. This is due to the proposed benefits of providing athletes with instant feedback during training sessions, estimating daily one repetition maximums for an exercise using load-velocity profiles, and implementing velocity-loss thresholds to adjust loads during training sessions (1). Collectively, it is believed that VBT then serves as a means of autoregulation in which testing and monitoring occur while training. While there are many different VBT devices, their primary purpose is to provide mean and peak barbell velocity data to practitioners. Despite the varied ability of VBT devices to provide this information, barbell velocity may not always serve as the best indicator to how an exercise is being performed. This may be due to the fact that there are different types of velocity that occur during a given exercise.

Types of Velocity

Barbell Velocity

Strength and conditioning practitioners who use VBT understand that mean and peak barbell velocity are the primary metrics that are tracked during training. However, it is important to note how these metrics are determined. Barbell velocity may be measured using a variety of devices including 3D motion capture, linear position transducer, inertial measurement units, video, etc. For example, linear position transducers such as the GymAware RS attach directly to the barbell and measure the displacement (while compensating for horizontal displacement) of the movement and the duration of the movement. Thus, barbell velocity is determined by dividing the displacement (meters) by the time or duration of the movement (seconds). In contrast, inertial measurement units may attach directly to the barbell and determine the acceleration and duration of the movement. The acceleration can then be integrated over time to determine barbell velocity via the equation:

Barbell Velocity = Initial Barbell Velocity + (Barbell Acceleration x Δ Time) 

Something that is important to note about barbell velocity is that it does not account for what has been produced by the body. Simply, barbell velocity serves as the result of what was produced by the body and was transferred to the barbell. While it is generally thought that these values should be the same, researchers have shown that there are differences between barbell, system (i.e., center of mass) velocity, and body (3D marker placed on sacrum) peak velocities during the squat, weighted jump squat, and hang power clean (2) and the deadlift exercises performed across a spectrum of loads (3). Assuming the barbell stays in contact with the body (e.g., rack on the shoulders during a back squat) during a movement, one would expect the differences between barbell and system velocities to be similar; however, the same cannot be said for weightlifting movements and their derivatives in which the barbell and body move independently.

Peak Barbell Velocity

System Velocity

The velocity of the system (i.e., center of mass) is the product of the forces produced by the body. If a resistance training exercise is performed on a force platform, practitioners can determine the system velocity through a series of equations (below). First, net force must be calculated by subtracting the system weight in Newtons from force. From here, acceleration at each data point can be determined by dividing net force by the system weight in kilograms. Finally, the same velocity equation shown above allows practitioners to integrate acceleration over time to determine velocity. It should be noted however, that when using force plate data to determine system velocity, an initial velocity of zero is necessary. In other words, an individual must stand still with the load on the force plate before the movement begins.

Net Force = System Force – System Weight (N)
Acceleration = Net Force / System Weight (kg)
System Velocity = Initial Velocity + (Acceleration x Δ Time) 

As noted previously, the barbell travels independently from the body during weightlifting movements and their derivatives. Following the second pull (i.e., triple extension), the barbell is elevated, and athletes pull themselves under the barbell in preparation to perform the catch phase. This in turn leads to the barbell and body moving at different velocities in opposite directions. Similar to the previous research highlighted above, a recent study showed that mean and peak barbell velocity was significantly faster than their system counterparts during weightlifting catching and pulling derivatives performed from loads ranging from 20-140% of the subjects’ 1RM hang power clean (4).

Peak System Velocity

Which Velocity is important?

Exercise Type

While the monitoring of barbell velocity has become a mainstay within VBT, strength and conditioning practitioners must consider whether they would like to monitor mean or peak velocity. In addition, the differences between barbell and system velocity must be considered, especially since the latter may serve as an underpinning factor of the former. Regarding mean and peak velocity, a rule of thumb should be to determine the nature of the exercise. For example, non-ballistic exercises performed without the intent to leave the ground (e.g., squat) or project the barbell (e.g., bench press) may be best served by monitoring mean velocity. In contrast, exercises that are performed with ballistic intent in which the goal is to move the barbell as fast as possible should be tracked and monitored using peak velocity. While jumping exercises such as jump squats are self-explanatory, the rationale for including peak velocity instead of mean velocity during weightlifting movements is due to the technical nature of the exercises. For example, depending on the variation, a first pull and/or transition phase may be performed in a controlled manner before the second pull is performed maximally. Interestingly, barbell velocity during the transition from the top of the knee to the mid-thigh (power) position may result in either a maintenance or even a decrease in barbell velocity, which may negatively impact the resultant mean velocity (5).

Athlete Considerations

Beyond the nature of an exercise, strength and conditioning practitioners should consider whether barbell or system velocity is more indicative of an athlete’s performance. For example, weightlifting coaches and researchers have indicated that peak barbell velocity is an underpinning factor of whether or not a snatch lift may be successful (6). Thus, it could be argued that barbell velocity is an important variable to monitor throughout training to determine the progress or regress of a weightlifting athlete. In contrast, it may be argued that system velocity is more important for non-weightlifter athletes who perform weightlifting movements and derivatives in their training since making snatches, cleans, and jerks does not determine their success in their sports or events. Therefore, monitoring mean and peak system velocity may serve as a better indicator of performance for non-weightlifting athletes. Despite this, it should be noted that besides force plate technology, there is currently no known alternative to measure system velocity. Moreover, very few facilities have the capacity to fit their weight room with force plate technology.

Conclusion 

  • Using certain VBT devices to monitor mean and peak velocity could benefit strength and conditioning practitioners and provide them information to benefit athlete motivation and progress/regress.
  • Beyond barbell velocity, system velocity may be calculated from force plate technology and provide an alternative to monitor an athlete’s performance during resistance training exercises.
  • Because barbell and system velocity may be considerably different, practitioners should note that system velocity may serve as an underpinning factor that ultimately produces barbell velocity during an exercise.
  • Resistance training exercises that are non-ballistic or ballistic may be best monitored using mean and peak barbell velocity, respectively.
  • Barbell and system velocity may provide valuable insight for weightlifters and non-weightlifters based on the nature and goals of their training, respectively.

References

  1. Weakley J, Mann JB, Banyard H, McLaren S, Scott T, Garcia-Ramos A. Velocity-based training: From theory to application. Strength Cond J. 2021;43:31-49
  2. McBride JM, Haines TL, Kirby TJ. Effect of loading on peak power of the bar, body, and system during power cleans, squats, and jump squats. J Sports Sci. 2011;29(11):1215-21.
  3. Blatnik JA, Goodman CL, Capps CR, Awelewa OO, Triplett NT, Erickson TM, et al. Effect of load on peak power of the bar, body and system during the deadlift. J Sports Sci Med. 2014;13(3):511-5.
  4. Suchomel TJ, Kissick CR, Techmanski BS, Mann JB, Comfort P. Velocity-based training with weightlifting derivatives: Barbell and system velocity comparisons. J Strength Cond Res. 2024;39:135-46.
  5. Enoka RM. The pull in Olympic weightlifting. Med Sci Sports. 1979;11(2):131-
  6. Ho LKW, Lorenzen C, Wilson CJ, Saunders JE, Williams MD. Reviewing current knowledge in snatch performance and technique: The need for future directions in applied research. J Strength Cond Res. 2014;28(2):574-86.

    Download: How to get started with velocity based training [use case]


    Dr. Tim Suchomel

    Dr. Tim Suchomel

    Dr. Tim Suchomel is the Director of the Sports Science Program and an Associate Professor at the University of Pittsburgh. Renowned for his research on strength and power development, training strategies, and athlete monitoring, he has made significant contributions to the field. With more than 110 peer-reviewed publications and over 60 podium presentations, Dr. Suchomel is widely respected in the strength and conditioning community.