• Hot Topic Power and Bar Velocity Measuring Devices
    Velocity-measuring devices can improve training, increase an athlete's competitive atmosphere, and add a level of fun to the workout. This research describes why coaches should include power and bar velocity in their strength coach’s toolbox. Part of the Hot Topics series.
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  • A barbell showing NSCA platesIntroductionWhen training with the intent of improving sport performance, Rate of Force Development (RFD) may be one of the most important issues to consider. An example of this concept was presented in Kurz’s book, The Science of Sport Training: How to Plan and Control Training for Peak Performance (4). 

    In the book, Kutz provides an example that involves the performance of two shot-putters; one, extremely strong with a bench press of 500lbs, and the other slightly less only bench pressing 400lbs.

    However, the shot-putter with the lower bench weight could express his strength more quickly than his counterpart, and thus performed better in competition. 


    Tracking real-time velocity and power can help determine whether an athlete moves weights at a proper velocity to improve a specific, high-speed strength or not. Gains on the athletic field come very specifically, and if someone is gaining strength, but not gaining performance, then their strength gains are not functional.

    Simply improving absolute strength may not show gains in the appropriate playing arena as shown from the shot-putter’s example.

    There are many devices that measure velocity and power of movement; some units measure displacement and time to calculate velocity and power. Many measure peak and average velocity as well as power.In this context, average refers to the average of one repetition (i.e., from beginning to the end of the repetition). Research has shown some units provide both a valid and reliable means to calculate velocity and power (1). To prevent confusion, all velocities mentioned in this article are average velocities. The purpose of this Hot Topic is to show how to use velocity to improve an athlete’s RFD.

    How is Velocity Measured and How Can it Help my Athletes?Some devices use a small microcomputer attached to a canister with a reel that measure the distance moved by the cable that is attached to the bar. This reel uses the distance measured and the time taken to perform the movement to calculate the velocity of the bar.

    The device can be likened to the speedometer in a car, helping to determine the appropriate load for an exercise by displaying the velocity at which the bar is moving. When dealing with an athlete, it is an instantaneous objective feedback tool. If the athlete were moving too fast or too slow, it would let them know that the load must be adjusted (increase or decrease in load based on speed, in m/secs). 

    The athlete should always produce force as fast as possible with correct form in the concentric portion of the exercise; the velocity that is shown will aid in determining the necessary adjustment to the load.For years, Soviet researchers examined every variable of training to determine what the optimal weight of the bar should be for various exercises. One result of this examination is the AS Prilepin Table for optimal repetitions at various intensities (2). During this examination, researchers examined the velocity of the bar for various movements and traits and developed optimal velocities for these exercises.

    From these examinations they established that too high of a velocity indicated that the weight on the bar was too light, and too low of a velocity indicated that the weight on the bar was too heavy. They found that a power clean had an optimal velocity of 1.25m/secs and a hang snatch had optimal velocity of 1.96m/secs (3). This is not to say that an athlete cannot perform the exercise with a heavier weight, it just suggests that it is just not optimal. 

    Training with weights greater than this may lead to overtraining or possibly a suboptimal adaptation.  
    For instance, an athlete desires to develop strength-speed on a squat which would be developed at 0.8 – 1.0m/secs, but only moves at 0.5m/secs. The athlete may have performed a squat, but did not complete the exercise at an appropriate velocity to develop the desired trait.

    By using the velocity to determine the weight, you enable the athlete to select a weight that is specific for them for that day. As with all things in training, some days are good, and some days are bad. The good and bad days will be demonstrated as such in the form of the velocity. By attempting to train at a certain velocity, the weight will be adjusted up or down to fit the needs of the athlete for that set.

    An unintended consequence, or benefit depending on the way it is examined, of the use of velocity measuring devices during training is how it plays into the competitive nature of the athlete. The nature of the immediate, objective feedback given by the device engages athletes training together to compete with one another. For example, two athletes perform cleans with 220lbs on the bar. The first athlete moves the bar at 1.35m/secs, and the second moves the bar at 1.45m/secs.

    When performing the next set, the first athlete will inevitably try to best the other athlete’s high score. This tends to add an element of fun and competition to the training session.

    AutoregulationAutoregulation is the regulation of the training of the individual based upon their state of readiness. The training is then altered by changing training volume or intensity (often both), as well as exercises, to meet the needs of the individual. Velocity measuring devices can be used in a mild form of autoregulation by using the velocity to determine appropriate loads. 
     
    The use of velocity enables the practitioner to determine the appropriate load for the day, not based on a testing session that occurred weeks, or even months prior.Understanding that there are optimal lifting velocities used to determine optimal loads allows you to assign velocity to an exercise rather than an assigned intensity. The Neuromuscular System (NMS) is the system in charge of recruiting motor units to be able to lift a weight. 
     
    If the NMS is overly fatigued, the athlete will not be able to recruit motor units as quickly, or in the proper sequence. This means that an athlete will not be able to lift a load as quickly and will need to reduce the load to be able to maintain optimal velocity.

    The use of velocity measuring devices as a form of autoregulation can be especially effective with the student-athlete population. During the course of the semester, student-athletes not only have training in the weight room, but practice, school, and, more than likely, relationships that put added stress on them. By neglecting the other stressors, the practitioner may overtrain the athlete by continuing to train at high volumes and/or intensities.

    The use of the velocity allows you to train your athletes at the appropriate weight, which may assist in the prevention of overtraining.

    Different Velocities for Training Different TraitsThe body adapts to training according to the Specific Adaptation to Imposed Demands (SAID) principle. This principle states that the body will adapt to whichever demand is specifically placed upon it. Velocity measuring devices allow specificity of demands to be known based on predetermined velocities. Different traits can be trained with different velocities and in most cases speed-strength, strength-speed, and absolute strength are traits that can be trained.

    Speed-strength can be defined as a method that targets developing strength with speed being the main priority and strength-speed can be defined as a condition of speed where the objective is to build strength with speed being the secondary priority. Absolute strength can be defined as the ability to lift the absolute maximal weight. 

    The same exercise can be used to develop different traits (speed-strength, strength-speed, and absolute strength) by moving at different velocities, as specific demands are placed upon an athlete. For instance, the squat, when moved at 0.1 – 0.35m/secs will develop absolute strength, at 0.8 – 1.0m/secs it develops strength-speed. If one simply adds a jump, the squat jump moves at 1.5m/secs and develops speed-strength (3,6). However, if development is attempted at strength-speed (0.8 – 1.0m/secs) and the weight is too heavy and only allows the bar to move at 0.5m/secs, then strength-speed will not be properly developed.

    Power vs VelocitySome practitioners who use velocity measuring devices do so to track power and manipulate loads to get the greatest power output possible. This is a perfectly acceptable method of using velocity measuring devices. However, training by velocity does have one advantage over training by power output.

    The advantage is that there are already established velocities for most exercises, and having this established number gives a better clue to the practitioner of how to manipulate a load. If a heavier weight is moved at the same velocity or faster, then more power is being developed. By knowing the specific velocities to choose appropriate loads, then the practitioner is able to impose a specific demand on the body.

    If a practitioner desires to develop RFD improvement in an athlete, moving a load that is 60% of a 1RM may be an appropriate load, but RFD improvement may not be seen if the individual is moving the weight slowly. Velocity measuring devices help to ensure that improvements will be given to RFD by the use of instant feedback of velocity with appropriate velocity ranges in mind.

    Table 1 is a basic chart of average velocities that can be used with velocity measuring devices.

    Velocity Measuring Device
    Table 1. Average Velocities for Velocity-Measuring Devices 
    Adapted from Roman, (1986); Ajan and Barago (1988)

    ConclusionThe use of velocity measuring devices provides immediate feedback which allows for a real-time analysis if appropriate loads are being used when performing work to develop the RFD as well as the autoregulation of the training load. 
     
    Velocity measuring devices can improve specificity of training, increase the competitive atmosphere, and add a level of fun to the workout. While these devices are not an end-all, be-all for training, they certainly have their place in the strength coach’s toolbox.
  • Mann

    About the Author:

    Bryan Mann MS, PhD, CSCS

    Bryan Mann, MS, PhD, CSCS, is the Assistant Director of Strength and Conditioning at the University of Missouri. With 14 years of professional strength and conditioning experience, he also serves as an Assistant Professor in the departments of Physical Therapy and Athletic Training.

    REFERENCES →


    1. Jennings, CL, et al. The reliability of the FitroDyne as a measure of muscle power. J Strength Cond Res, 19(4): 859 – 863, 2005.
    2. Siff, MC. Supertraining. (5th ed.) Denver, CO: Supertraining Institute: 495, 2000. 
    3. Roman, RA, The Training of the Weightlifter. (1st ed.) Moscow: Sportivny Press; 165, 1986.
    4. Kurz, T. Science of Sports Training: How to plan and control training for peak performance. (2nd ed.) Island Pond, VT: Stadion Publsihing Company Inc.; 423, 2001
    5. Kraemer, WJ, Fleck, S. Optimizing Strength Training, Designing Nonlinear Periodization Workouts. (1st ed) Champaign, IL: Human Kinetics; 245, 2008.
    6. Baroga, TAL. Weightlifting: Fitness for All Sports. (1st ed.) Budapest, Hungary: International Weightlifint Federation; 485, 1988.

  • Disclaimer: The National Strength and Conditioning Association (NSCA) encourages the exchange of diverse opinions. The ideas, comments, and materials presented herein do not necessarily reflect the NSCA’s official position on an issue. The NSCA assumes no responsibility for any statements made by authors, whether as fact, opinion, or otherwise. 
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