Let’s provide a real-world example:
Imagine an athlete walks into the gym and they are programmed to perform the back squat for 5 sets at 75% of their 1-RM. Well given the fact their 1-RM today may be 15kg lower than it was two days ago when their 1-RM was determined, this 75% load may actually be closer to 85-90% of their 1-RM. This may explain why athletes feel strong on one day, and weaker on others.
To elaborate on this, research has shown that the traditional approach of training to repetition failure does not necessarily lead to greater increases in strength and/or hypertrophy [35, 36]; potentially because effort and overall volume-load (load * reps * sets) are reduced due to fatigue. In fact, one study  has reported that the traditional approach of training using self-selected repetition velocity was less effective for developing strength when compared to a velocity based approach, whereby sets were terminated when the repetition velocity dropped below a 20% threshold; known as a ‘cut-off velocity’.
Cut-off velocities, also known as velocity stop values, are used to terminate/stop a set when the mean concentric velocity of a repetition falls below that value. Experts have suggested using cut-off velocity values of 30% in the squat, and 35% in the bench press . This means that when an athlete’s repetition velocity drops by more than 30% in the back squat, then the set should be terminated to prevent them from performing unnecessary repetitions and hampering the desired adaptation.
Cut-off velocities, also known as velocity stop values, are used to terminate/stop a set when the mean concentric velocity of a repetition falls below that value.
There are two common ways of using cut-off velocities:
- The cut-off value (e.g. 30%) is determined based upon the athlete’s first repetition velocity.
- The coach can pre-determine cut-off values based upon the athlete’s load-velocity profile.
Though both of these methods are useful, the first method is perhaps the easiest and most accurate since any pre-determined cut-off values used in the second method can be affected by daily fluctuations in athlete freshness. Not only this, but many velocity based training devices display the velocity drop-off anyway.
Now without trying to overcomplicate things and overload your brain, you should be able to see how cut-off velocities correspond to the repetitions in reserve, and therefore, allows the coach to prescribed loads and/or terminate sets when an athlete has a set number of ‘reps left in the tank’.
Using Table 4 as an example, if an athlete is performing a set of back squats using 75% of their 1-RM and their mean concentric velocity drops to 0.39 m/s, the coach can determine that the athlete has approximately 2 reps left in the tank (highlighted in orange). Being able to identify how many repetitions an athlete has left in the tank allows the coach to adjust the training load and volume in order to target the desired physical quality.