Velocity loss training for strength - made simple!

Efficient strength training using velocity loss as a guide to reps could actually be very simple, thanks to some brand new research!

As our regular subscribers will know from previous articles, the evidence for the benefits of strength training for athletes at all ability levels is considerable and extremely robust, and continues to grow more robust with each passing year. Adding some strength training to a training program not only delivers greater levels of muscular power and strength – a clear advantage for athletes whose sports require these qualities – but also increases musculoskeletal resilience, thereby significantly reducing the risk of injury⁽¹⁾.

In addition, studies on endurance athletes such as runners and cyclists have shown that the use of lower-body, heavy-weight resistance exercises can improve muscle economy⁽²⁾ . In short, this means that muscles become more efficient at converting chemical energy into forward motion, which in turn means that less energy and oxygen is required to sustain a given pace, resulting in less fatigue, especially in longer duration events. The benefit of improved muscle economy overstated in endurance sports because research shows that excellent economy is a key factor for the superior performance of elite athletes⁽³⁾.

Strength training structure

Strength training requires time and effort, so it’s important that athletes structure their training to get the maximum performance benefits with the minimum effort and resultant fatigue. The traditional approach to strength training has focused heavily on conducting a pre-determined number of repetitions while using a pre-determined load. However, there are a number of other approaches that have been explored more recently. These include holding back some ‘reps in reserve’ (see this article) and using the change in speed of each rep as the set progresses to determine the best end point –and therefore the optimal number of repetitions - of the set (see this article by Andrew Sheaff).

Although the traditional approach of prescribing training loads using a % of 1-rep max and aiming for a fixed number of reps per set relatively simple and practical and can be managed with relative ease with large groups of people, it doesn’t account for physiological and psychological stressors that can affect an individual’s day-to-day performance⁽⁴⁾. For instance, maximal strength can fluctuate daily when an individual is fatigued or significantly increase within a few weeks due to training adaptation⁽⁵⁾. Furthermore, the number of repetitions that can be completed against a given % of 1-rep max has been shown to be both individual- and exercise-specific⁽⁶⁾.

Velocity-based approach

A more recent and very promising approach to determining the best reps/sets structure for strength trainers is the use of ‘velocity based training’. As Andrew Sheaff explains in his article on this topic, with a velocity-loss (VL) approach, training sets are not performed with a pre-determined number of repetitions. Instead, the velocity loss (ie slowing of the exercise movement) over the course of a set will determine when the set is finished. Once a certain percentage of the initial speed is lost, the set is over. For example, if the initial reps are performed at 1.0 meters/second, the set will continue until the athlete can no longer maintain a velocity of 0.7 meters/second. Velocity loss is really a measure of how much fatigue has been generated over the course of the set. As greater velocity loss implies greater fatigue, measuring the velocity loss is really about measuring, and controlling, fatigue.

The science behind the use of a velocity approach is robust. Research shows that monitoring VL reached in each set serves as a precise method of quantifying the level of effort expended⁽⁷⁾. A number of studies using a VL approach to resistance training have examined the effects of training with different magnitudes of velocity loss on maximal strength, hypertrophy, muscle endurance and performance of athletic tasks.

In brief, higher VL (losses in velocity over 20%) appear to maximize hypertrophic (muscle gain) adaptations but result in a significant reduction in the II-x muscle fiber types⁽⁸⁾. For athletes, this is undesirable as type IIx fibers have the capacity for both high-intensity work but are also well endowed for energy production using oxygen metabolism. In short, endurance athletes who also need to be able to sustain very high intensities (eg in a long sprint for the finish line) need to nurture their type II-x muscle fibres!

By contrast, lower levels of velocity loss (under 20%) seem to produce similar improvements in muscle strength and endurance as well as performance of sport-specific tasks such as vertical jumping and sprinting. However, research also shows that there might be an upper and lower VL threshold to induce optimal training adaptations; in a 2020 study, researchers concluded that moderate VL thresholds (ie between VL10 and VL20) should be chosen to optimize sport-performance adaptations to strength training⁽⁹⁾; below VL10 provides an insufficient stimulus to generate adaptation whereas above VL20 produces more muscle hypertrophy but reduces the all-important type II-x fiber types.

Drawbacks of VL training

If the benefits of using a velocity based approach to strength training are so well understood, why hasn’t it become more widely used among coaches and athletes? The reason is simple; using VL training requires the use of valid and reliable velocity measuring devices (eg linear position transducers). While the cost of these devices has decreased in recent years, they are still not affordable to many. And even if velocity measuring devices are available, their use with groups of people can be an impractical task (eg in team sports and group sessions).

Because of these limitations, researchers have investigated alternative training approaches, which follow the principles above – ie allow athletes to undergo strength training with only small amounts of velocity loss (10-20%) – but which are simpler to implement. One option is cluster sets, where intra-set rest periods are implemented - eg a set of nine reps is broken down into three blocks of 3 reps, by inserting two short rests into the set. Cluster sets are a straight-forward method to reduce fatigue while allowing higher velocity repetitions to be performed and maintained during strength training⁽¹⁰⁾.

The problem with cluster sets however is that they extend total training time relative to traditional % rep-max training, which might not always be feasible from a practical standpoint. A more time efficient alternative to cluster sets is to simply redistribute the total rest time of traditional training to include shorter and more frequent rest intervals. This approach is known as rest redistribution (RR), and has been shown to be effective (albeit to a lesser extent than cluster sets) in alleviating acute metabolic, and perceptual markers of fatigue, and at inducing positive training adaptations⁽¹¹⁾.

VL training without the drawbacks?

Given the above, is it possible that both cluster set and rest redistribution set structures could be used as a simple and intuitive alternative to commonly used VL thresholds? There’s some evidence that these alternatives could work; a 2017 study examining the effects of cluster and rest redistribution sets observed that 12-second inter-repetition rest periods allowed for 36 consecutive back squat repetitions to be performed without dropping below VL20⁽¹²⁾. More recently, researchers recently showed that rest redistribution allowed almost all repetitions (17.5 out of 18) in a clean pull exercise to be performed with less than 20% VL, regardless of the load used across three sets⁽¹³⁾.

That’s all well and good, but the recent research on cluster sets and rest redistribution has not compared these methods with traditional % rep-max training. What’s needed is a study that compares these alternatives with traditional training – specifically in terms of numbers of reps achievable with velocity losses between 10 and 20% (the ideal level of induced fatigued for athletes seeking improved strength-mediated performance). Up until now, that data has not been available, but a brand new study published in the journal ‘Peer J’ has answered this very question⁽¹⁴⁾.

New research

In this study, researchers set out to examine the effects of different set configurations on velocity loss towards the end of a set. In particular, they wanted to find out whether cluster sets or rest redistribution could be a simpler but still effective alternative to using a 20% velocity loss threshold. Thirty one resistance trained participants, with at least one year’s training experience reported to the lab on four occasions within a 2-week period. During the first visit, each subject underwent testing to find out their 10-rep maxes (the higher weight that allowed 10 reps to be completed with strict form) for the squat and bench press exercise performed on a Smith machine. Thereafter, participants reported to the laboratory on three occasions (i.e., experimental sessions) during which they performed bench press and squat exercises using different set structures, with resistance set according the each athlete’s 10-rep max load established above. These structures were as follows:

• Traditional - three sets of 6 continuous repetitions with 3 minutes of inter-set rest
• Cluster - three sets of 6 repetitions with 30 seconds of intra-set rest every 2 repetitions and 3 minutes of inter-set rest
• Rest redistribution – nine sets of 2 repetitions with 45 seconds of inter-set rest

All the set structures were performed with ten minutes of rest between the squat and bench press exercises. Sessions were separated by 48 to 72 hours of rest and were performed in a randomized order with the squat/bench press exercises performed in the same order during all three sessions. Each experimental session was preceded by a standardised warm-up. Barbell velocity was collected during all repetitions using a linear velocity transducer interfaced to a computer by means of a data acquisition board and custom software. Throughout the sessions, strong verbal encouragement and visual velocity feedback were provided to ensure that participants performed the concentric (lifting) phase of the exercises with the maximal intent. All sessions for the same participants were held at the same time of day (±1 hour) to minimize the effects of the circadian (daily) rhythm on physical performance.

The findings

The main findings of this study revealed the following:

• The inclusion of 30-second intra-set intervals during cluster sets, and creating shorter but more frequent rest periods during rest redistribution, prevented the much of velocity losses experienced when the traditional approach was used (see figure 1).
• Comparing cluster sets and rest redistribution, the latter was the most effective set structure for preventing velocity losses.
• The beneficial effects above were more pronounced during the bench press exercise than with squats (ie the degree of velocity losses with cluster sets/rest redistribution was lower).
• Both the cluster set and rest redistribution structures allowed the vast majority of repetitions to be performed while limiting velocity losses to under 20% (ideal for athletes).

Taken together, the findings show that the use of cluster sets and rest redistribution are effective at reducing the overall fatigue-induced decrease in velocity compared with the traditional (fixed reps at % of rep max), and are likely to allow the vast majority of repetitions to be completed with velocity losses of under 20%.

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Figure 1: Bench press and velocity losses

Data here shown for bench press. NB: BP = Bench press; CS = Cluster set structure; RR = Rest redistribution set structure; TS = traditional structure. The dashed line represents a 20% velocity loss threshold, below which is undesirable. Each dot represents one data point. The large black dots on the bold lines represent the average velocity loss across the set. The curves represent the distribution of the data. It can be seen clearly that the cluster set and (particularly) rest redistribution set allowed far more reps to be completed before velocity losses exceeded 20%.

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Practical implications

These results are fascinating suggesting that for athletes seeking maximum sports performance, the traditional (reps performed at a fixed % of rep-max) structure can be bettered. We need to add the caveats that this study a) only looked at two exercises, b) was performed using a Smith machine (ie not free weights) and c) that the participants were well trained but not training at the elite level. Having said that, it seems that using either cluster sets or rest redistribution structure to your sets will get you more reps in the ‘Goldilocks zone’ – ie reps where velocity losses at full effort are between 10 and 20% of velocity when you are completely fresh. Remember, the reps in this band are the ones that are key to improved athletic performance because they maximally stimulate adaptations in the muscle, yet preserve type II-x muscle fibers.

If you want to try this approach, you can easily use the protocol above:

• Find your 10-rep max for the exercise in question.
• For cluster sets, perform three sets of 6 repetitions with 30 seconds of intra-set rest every 2 repetitions and 3 minutes of inter-set rest.
• For rest redistribution, perform nine sets of 2 repetitions with 45 seconds of inter-set rest.

This protocol can easily be adapted. For example, if you normally perform three sets of 8 reps using a traditional approach, add another two repetitions to the above when doing cluster sets. If you want to adapt to rest redistribution, you would perform twelve sets of 2 reps with 45 seconds of inter-set rest. Remember, the key is to emphasize the maintaining your initial velocity throughout these sets while keeping your form strict!

References

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14. 2022 Mar 29;10:e13195. doi: 10.7717/peerj.13195. eCollection 2022