This is an excerpt from Science and Practice of Strength Training-3rd Edition by Vladimir M. Zatsiorsky,William J. Kraemer & Andrew C. Fry.
The process of testing for maximal strength can be a tedious and demanding process. This is especially the case when very large loads can be lifted, as in barbell squats, deadlifts, bench presses, and cleans. One alternative method for estimating 1RM strength is to use velocity-based testing. This involves assessing the lifting velocity at a number of submaximal loads, from which a regression line can be created to determine the loads corresponding to 100% 1RM loads (see figure 7.22). This point is the estimated 1RM strength for the exercise, although this value may be affected by the individual's training status. While this method of strength testing may be useful in some practical settings, close examination of these testing methods shows there is occasionally considerable variability in the results. Large day-to-day variability in velocity at submaximal loads can produce large differences in the slopes of these lines, and the estimated 1RM strength. Indeed, repeated testing using this method produces greater variability than does actual testing at 1RM loads. This, however, does not mean that velocity-based 1RM testing does not serve a role. Since actual 1RM strength is resistant to short-term fluctuations in the weight room training load (see chapter 9 on overtraining), changes in velocity at submaximal loads may serve as a more sensitive indicator of training stress.
Figure 7.22 Examples of load-velocity curves for four exercises showing how extension of the regression line to 100% 1RM values can provide an estimate of 1RM strength. Note also how some exercises have a different load-velocity relationship (e.g., power clean).
Adapted by permission from B. Mann, Developing Explosive Athletes: Use of Velocity Based Training in Training Athletes, 3rd ed. (Muskegon, MI: Ultimate Athlete Concepts, 2016), 48.
Using lifting velocity to determine training session loads and exercise prescription may be a helpful tool for several reasons. First, prescribing loads based on the measured lifting velocity ensures the athlete is training in the desired training zone. Figure 7.23 shows the load and velocity ranges corresponding to popular categories of strength characteristics. Second, since there is so much interindividual variation in the lifting capacities at a prescribed percentage of 1RM, using velocity to prescribe training loads—or velocity-based training—may result in greater accuracy when determining appropriate loads. This is not to say that velocity-based training is better than prescribing by relative or absolute loads (e.g., a percentage of 1RM or 10RM), but rather it is an alternative approach that some coaches find helpful. This may be especially true when training large groups of athletes who have a wide range of training experience and lifting capabilities.
Figure 7.23 Suggested ranges of velocities for many weight room exercises, and the strength characteristics associated with these velocities for high-level collegiate athletes. The zones may need to be adjusted for different populations. A = absolute strength, B = acceleration strength, C = strength-speed, D = speed-strength, and E = starting strength. Note that the weightlifting exercises (snatch, clean, jerk) are primarily at the right side of this figure, and the relative loads (percentage of 1RM) will be different as seen in figure 7.22.
Adapted by permission from B. Mann, Developing Explosive Athletes: Use of Velocity Based Training in Training Athletes, 3rd ed. (Muskegon, MI: Ultimate Athlete Concepts, 2016), 20.