A Unilateral to Bilateral Training Progression for Team Sports

Training team sport athletes is complex, with so many ways to prepare them and variables to consider. In truth, any program that allows for the progressive overload of various forms of intensity (not just weight lifted, but also increases in outputs of power, speed, etc.), performed with safe biomechanical positioning, will typically lead to positive results from a physical preparation context.

We see this time and time again with most high-level team sport athletes having similar levels of physical fitness despite each strength and conditioning staff having their own unique approach to the problem. However, team sports exist as multiple layers of complexity and chaos, and to have a better understanding of preparation protocols, it’s necessary to try and consider all the layers as best as possible.

‘Chaoplexity’

“The term chaoplexity brings together the theory of complexity and chaos theory…the complexity of the game exists in a world founded on chaos. Combine this with social laws, the rules of competition, and training or practice schedules, and we see that players are experiencing what can only be described as chaoplexity.” – Fergus Connolly

For me, part of this chaoplexity is understanding how all the various layers interact and how that will determine what I choose to do with my athletes from a physical preparation standpoint. This is especially important for younger developmental players who stand to gain a lot from physical preparation in their overall performance.

I want to expose my athletes to various motor skills and coordination challenges, bring up their power and capacity outputs, and do all of this while still considering the impact of skill acquisition, sports practice, and sports competition. I am in search of structured training variation, based on:

• Desired training effects
• Time of the year
• The specific athlete
• Multiple other factors

“Variation is the key to efficient coaching. This does not only apply to optimizing motor learning processes. When planning physiological adaptations during training, variation should again be the main feature of the training…Variation is therefore the first and most important training principle, along with individualization.” – Frans Bosch

This article presents one ideological approach I use in my current search for structured variation. This approach is specifically geared toward team sport athletes. Based on the demands of team sport physical preparation, I use a system that progresses the general (italicized on purpose) strength and power training by building a foundation of unilateral activities first, and then shifting toward a realization of high-power output with bilateral activities. This general training progression is layered with specialized forms of speed, power, agility, and endurance training performed in conjunction with what’s laid out here.

Varying Unilateral and Bilateral Strength and Power Training

First off, this is not a new concept. I know for a fact this idea has been used before (see the picture of Joe DeFranco’s notes from a Charles Poliquin seminar below). But for me, this whole idea started from a simple conversation with my good friend Chad Dennis, a highly experienced strength coach for the past 17 years.

Chad visited me at DeFranco’s Gym in New Jersey earlier this year, and I reviewed my training program principles with him. I was trying to add some variability into my program by alternating between unilateral and bilateral emphases for strength and power every couple of weeks. At the time, I was operating based on a couple of things I had learned. Number one, thanks to some reading on recent theories of motor learning, I learned the importance of variability for resilient, adaptable skill development. Number two, thanks to plenty of conversations with my friend Mike Boyle, I learned that unilateral training is typically an untapped area of potential for great training effects. I knew I wanted to try to include both concepts in my program, so this was the solution I developed.

I wanted to include both variability, which is important for resilient, adaptable skill development, and unilateral training, a typically untapped area of potential for great training effect. Share on X

Chad reviewed my notes and then took a couple of breaths before asking me, “Have you ever tried doing a foundational period of unilateral emphasis followed by a specialized period of bilateral emphasis?” I asked him to elaborate on his thoughts, and he said, “Well, for me, I tend to look at unilateral power as falling more in line with ‘strength,’ whereas bilateral power seems to align better with ‘speed.’ There’s something there with the kinetics and the ground contact times.”

Movement Physics Tell the Story, Not Movement Appearance

As soon as Chad said that, my mind wandered to two specific places. The first was Triphasic Training by Cal Dietz and Ben Peterson, where they wrote the following:

“A single leg plyometric, as shown by [a] motion analysis machine, is so much slower in producing forces…With double leg plyometrics…there is higher potential for developing speed because of the shorter amortization phase, and thus, a more explosive rebound…Single leg plyometrics should be viewed more as a strength plyometric whereas double leg plyometrics develop speed.” ⁴

We often assume that single leg training is more “sports-specific,” since most athletic actions occur on a single limb. When speaking strictly kinematically—that is, based on how a movement appears—then yes, that’s true. But when we consider the kinetics of the motions—that is, how the movement was caused in terms of the forces and time frames involved—we start to see that we can’t just look at the appearance of a movement. In order to better determine the desired training effect, we must also consider the physics involved.

The other place where this thought hit home for me was a recollection of work by Derek Hansen highlighting ground contact time as a simple way to gain insight as to where training effects occur along the force-time continuum.

From this image, we can easily see how all these activities involve a single limb contacting the ground, but the force-time components of each action and ground contact are very different. Sprinting at top speed will ultimately require a single leg action that is at least four times faster than that of coming to balance in a full deceleration.

It’s not enough to think in terms of “single leg is more specific” when designing programs—it’s the overarching desired training effect that is most important. Share on X

So, it’s not enough to think in terms of “single leg is more specific” when designing programs—it’s the overarching desired training effect that is most important. As I discovered, taking a broader perspective on the why’s of training brings up some interesting thoughts and questions into when, how, and why to use different forms of unilateral and bilateral training.

Unilateral vs. Bilateral Power

Unilateral power and plyometric training are growing in popularity, especially with team sport athletes for whom having the ability to display power on one limb in multiple directions is an obvious advantage due to the demands of the game. Training in multiple planes seems to be an important factor, with research supporting the notion that having single leg power, deceleration, and coordination in multiple planes is an area of necessity when designing training programs for team sport athletes.^{1, 9, 10, 12}

Both bilateral and unilateral power training will result in general adaptations associated with improvements in power, namely speed of muscle contraction, faster motor unit activation, enhanced neural firing rates, decreased duration of the stretch-shortening cycle, and improved proprioception. However, there are specific adaptations that occur depending on the training means used.

The reported training effects following unilateral power and plyometric training may occur over a period of 6–12 weeks. These effects seem to follow the SAID principle, where specific adaptations occur based on imposed demands. So, it’s typically reported that training with unilateral activities will have the greatest impact on unilateral actions, though some research has suggested that bilateral countermovement jump performance may also improve following a period of unilateral jump training¹.

Figure 2 presents some of the reported effects of unilateral power and plyometric training:

In addition, all locomotive motion will require the transmission of force into the ground with various time constraints (dependent on the task). Therefore, we can use ground contact times as a simple indicator of how unilateral and bilateral power activities might differ in their force-time expression and how they align with different athletic actions like accelerating, sprinting at top speed, changing direction, or decelerating.

Preparing for Collision

Another point of consideration with unilateral power training for team sport players relates to tissue resiliency and robustness. For contact sports like rugby and American football, collision is a major concern. Thanks to advances in integrated accelerometry (IA) technology, researchers can monitor the magnitude and frequency of impact and collision in team sport players.

It has been reported that the prevalence of high-velocity eccentric actions (i.e., changing direction and deceleration), in combination with tackling and other forms of impact trauma, induces a significant load to the players’ musculoskeletal systems, as evidenced by large elevations of creatine kinase (CK) and cortisol following match play. Soft tissue trauma is part of the game, and if players are loaded too much or too little in training, it stands to reason that noncontact soft tissue injuries are likely imminent.¹¹

However, it seems that the bulk of collision loading in contact sports like rugby and American football occurs in the form of ground-reaction forces generated by accelerating, changing direction, jumping, or rapid decelerations, all resulting in inertial load on the body.^{5, 15}

Force plate data has helped shed light on the magnitude of these impacts as measures of vertical ground reaction forces, which can range from 2–7 times the body weight of a team sport player during jumping, change of direction, and sprinting actions. Further, these are actions that are usually sustained on one leg due to the dynamics of team sport game play.

It’s worth mentioning that explosive/elastic activities incorporate a greater influence of the entire musculotendinous unit to help aid in force production. The greater contribution from elastic structures like tendons allows for the body to sustain such high forces. We simply cannot simulate these forces in a weight room, due to the slow nature of resistance training, which directly stresses the muscle more. Thus, it’s important that we incorporate power and plyometric activities to develop the tissue integrity, proprioception, and coordination required to perform rapid, explosive actions competently and safely.

“The moment you enter a gym, forget about specific training unless you are a bodybuilder, a powerlifter, or a weightlifter.” – Henk Kraaijenhof

One paper investigated the demands of American football using a workload-injury etiology model and determined the following³:

• Coaches and practitioners working with American football players need to expose them to a high number of collisions in training to better prepare players for game demands.
• A balance must exist between the number of exposures required to improve fitness and the number that elicits negative fatigue responses and increased injury risk.
• Players who can produce high average inertial load values were less susceptible to contact and noncontact soft tissue strains and sprains.
• Players with a high level of neuromuscular responsiveness and control can produce high inertial load values through rapid acceleration, deceleration, and change of direction, which may offer protective benefits.

So, being able to overcome the resistance of inertia with great efficiency seems to have a protective effect for team sport athletes. This information falls in line with how unilateral power training in multiple directions is a necessary training consideration for a complete team sport program. The forces of unilateral plyometric activity appear to be just as high as those of a bilateral countermovement jump, revealing a unique training stimulus that can help prepare the structures of the lower limbs for high impact loading at fast speeds.

The forces of unilateral plyometric activity appear to be just as high as those of a bilateral countermovement jump. Share on X

The research seems to indicate that the most complete training program is one that incorporates a combination of bilateral and unilateral power training. This makes sense when looking at the ground contact image in figure 3, where bilateral and unilateral power and plyometric activities are scattered all along the force-time continuum. 

Unilateral vs. Bilateral Strength

Speaking of implementing a complete program, we can’t neglect the development of muscular strength. It seems there are benefits to using both unilateral and bilateral means in this realm as well. The benefits of general strength training are well-established and beyond the scope of this article, but the primary adaptations associated with heavy resistance training include enhanced neural capabilities, increased energy stores, muscle gain and improvements in body composition, anabolic hormonal responses, and potential enhancement of ligament, tendon, and collagen integrity.⁸

Most resistance training research has investigated effects using bilateral strength exercises like the leg press, barbell squat, or barbell deadlift. The research regarding training for maximal strength using unilateral exercises pales in comparison to the research on bilateral barbell training. In practice, most coaches perform unilateral strength training, using exercises like rear foot elevated split squats, pistol squat variations, or single leg deadlift variations. The following is a quote taken from the classic training text Supertraining by Yuri Verkhoshansky and Mel Siff:

“Research has shown that the transfer of strength developed in bilateral training (e.g. using squats or power cleans) offers specific improvement in performance in bilateral events…while unilateral training (e.g. with dumbbells or split cleans) enhances performances more effectively in unilateral activity such as running, jumping.”

In recent peer-reviewed literature, the reported performance gains associated with unilateral strength training show similar effects to what is reported with bilateral strength training, which may be important for athletes who are contraindicated for exercises like barbell squats or deadlifts. If axial loading is an issue, especially for older athletes in contact sports who have experienced low back or hip injuries and feel discomfort when loading bilaterally, unilateral exercises may prove to be an effective form of strength training for the lower body.

In recent peer-reviewed literature, the reported performance gains associated with unilateral strength training show similar effects to what is reported with bilateral strength training. Share on X

Thus, more work is needed before we really understand what adaptations occur from heavy unilateral strength training.

In my own experience using unilateral exercises with my athletes and conversing with them about the movements, most of them tell me that they feel an element of athleticism with the unilateral strength exercises. I imagine that this is due in part to unilateral exercises emphasizing cross-body patterns and putting the joints in positions with more degrees of freedom, requiring more stability.

Here are some of the reasons that I personally like using unilateral strength exercises, especially early in a developmental training progression:

• Unilateral strength exercises are naturally more unstable, emphasizing stability, coordination, and balance in the face of more degrees of freedom.
• Due to greater instability, athletes should perform unilateral strength exercises with a controlled tempo, emphasizing time under tension for greater local muscular endurance and hypertrophy.
• Unilateral strength exercises will reduce the overall axial load, allowing for a period of unloading the spine while emphasizing strength and tension of the local leg musculature early in the training process.
• With split patterns and positions, mobility may be trained against load in positions like deep hip/knee flexion, hip extension, and ankle dorsiflexion while minimizing spinal compression.

Field First, Weight Room Second

In my programming, I always take a skill-centric view and work backward from the athletic qualities needed in the sports game. This means that I always think in terms of field first, weight room second.

Certain athletic activities will demonstrate massive vertical ground reaction forces in minuscule amounts of time—let’s just consider how top-speed sprinting can produce up to 6x body weight of vertical ground reaction force in about a tenth of a second on one leg! You just can’t match this kind of output in the weight room. I can find activities that may have a positive correlation and potential transfer to sprinting performance in the weight room, but if I really expect to build better sprinting with my athletes, I must have them sprint.

I always take a skill-centric view and work backward from the athletic qualities needed in the sports game. This means that I always think in terms of field first, weight room second. Share on X

The same goes for other athletic activities like jumping, change of direction, and deceleration. I must train these qualities as they exist on the field in order to keep the experience specific to what’s encountered in the game. So, for agility work, I will use game-like situations to put my athletes in positions that feature specific perceptual-cognitive elements to help hone their skills of anticipating, reading, and reacting appropriately to what they see.

A popular sprint training progression from Charlie Francis is the Short-to-Long Model, where we expose athletes to shorter distances (i.e., 10–20 yards) earlier in the training process and gradually progress to longer distances over time. This makes sense because shorter distances do not feature speeds or ground reaction forces that are nearly as intense as longer distances, where athletes reach top speeds. Therefore, athletes can train at high intensities of sprinting with less risk of structural damage early on by using shorter distances and gradually expanding their power and speed exposure with longer distances as the program carries on.

In similar fashion, when I train for change of direction speed or agility in the form of open/reactive game experiences, I use a progression of “small to large,” where I start with smaller field spaces early on and gradually increase to larger field spaces. By starting with small spaces, my athletes experience these high-intensity movements with less impact, since the spaces and movement speeds are reduced. As the program progresses, I use larger spaces, and changes of direction feature larger impacts from decelerating from higher movement speeds.

Common Denominators of Effective Programming

When I look at various texts on programming and periodization for sports, the principles seem to be consistent, regardless of the specific periodization model applied, whether it is the traditional model, vertical integration system, block periodization model, block training system, or whatever. There will always be a General Preparatory Period that initiates the training process, followed by a Specific Preparatory Period to emphasize more specific qualities, and finally a Competitive Period where the effects of training are realized in live competition. There is also a Transition Period of reduced loading following phases of competition or team sport seasons.

The Vertical Integration Model, also sometimes referred to as the Complex-Parallel Model (popularized by the late sprint coach Charlie Francis), seems to be the most advantageous approach for intermediate to advanced team sport athletes.

This model is characteristic of keeping all forms of training present throughout the entire year—hence, vertically integrating the training components like the traditional model—but rotating the emphasis of training into blocks or phases and accounting for greater inclusion of technical/tactical training. It is a system that falls somewhere in between the traditional model and the block models, where definitive blocks are used but all physical qualities are present to some degree all year long due to the nature of team sport requirements.

Team sports are incredibly complex in comparison to individual sports, with a wide array of physical qualities always needed, far more tactical strategy involved, and a greater repertoire of technical skills to develop. In addition, team sport athletes will not need the same level of physical output as an individual sport athlete. A sprinter lives by maximizing speed and a thrower lives by maximizing power, but a team sport player only requires enough physical output to operate effectively within the rules of the sport game.

Progressing from Unilateral to Bilateral Emphasis

The idea of progressing from a unilateral to bilateral emphasis for strength and power is about starting with a base of coordination and gradually shifting toward increasing motor outputs in the general training as the specific training on the field becomes more intense and more technical in relation to the sport. Thus, in team sports, this shift toward specificity will necessitate increasing the intensity and exposure to field-based activities with faster speeds, higher power, more intense change of direction, and greater perceptual-cognitive complexity using open/reactive games and agility training.

It’s also important to spread out the stresses of each training period so that the most important qualities can flourish. With unilateral training, there is an expectation of greater soreness in the local tissues and musculature. This can prove problematic when we want to really emphasize technical elements and intensified field training during the SPP. Sore legs make speed and technique work difficult.

It makes more sense to emphasize unilateral training when there is reduced field training intensity, typically earlier in the training process. Share on X

In the early training periods, specialized technical training is less of a priority, so it allows for the opportunity to stress the structures of the lower limbs with less worry of reduced quality in high-speed efforts or activities of high technical demand. It’s much easier to have a quality 10-yard sprint with some leg soreness than it is to have a quality 40-yard sprint. Therefore, it makes more sense to emphasize unilateral training when there is reduced field training intensity, typically earlier in the training process.

In the SPP periods, the primary unilateral emphasis shifts in favor of what’s being done on the field with more specialized training. Here, the field work must be of high quality to get the desired training effect. So, we can reduce local soreness by shifting the emphasis of the general power and strength work in favor of bilateral activities, which also gives us a nice one-two punch because the kinetic qualities of bilateral training align very nicely with higher speeds on the field.

With bilateral training, more power and speed are possible since the force effort is spread across more total body structures. Monitoring the velocity of barbell lifts shows that this is apparent, as a repetition of a barbell squat at 80% 1RM will move faster and with more power (due to greater load) than a repetition of a barbell rear foot elevated split squat at 80% 1RM.

IMPORTANT NOTE:

Just because the emphasis of a certain training phase may be on unilateral training, this does not mean that we abandon bilateral activities. On the contrary, keeping elements of bilateral training present while emphasizing unilateral training will prove fruitful, allowing for athletes to develop the motor control needed for bilateral activities that we will load later.

Just because the emphasis of a certain training phase may be on unilateral training does not mean that we abandon bilateral activities. Share on X

For example, I keep bilateral squat and hinge movements present in accessory weight training, using lighter loads and manipulating execution tempos to emphasize eccentric or isometric control. I also perform jump testing with my athletes all year long, so exposure to bilateral squat jumps, countermovement jumps, depth jumps, and the reactive strength index (RSI) is consistent in all phases.

What About the In-Season?

The main body of this article deals with the off-season preparation periods. However, given that the specific context is in relation to team sports, we come across an issue: Team sports like basketball, soccer, and volleyball require competition almost all year long. For these sports, there is a greater requirement to develop a knowledge of the stress imparted on players from sports practice and games and to make educated decisions on how to structure the in-season training.

In his new book, Methodology of Training in the 22nd Century, Coach Henk Kraaijenhof explains how we simply have to throw many periodization models out the window with in-season training, as the majority of the models were designed at times when athletes were simply not competing as frequently as they do in today’s commercially driven world. Thus, we must take a more agile approach, like the morphocycle design of tactical periodization pioneered by Vitor Frade and brought further to light in Fergus Connolly’s Game Changer and my most recent book with Fergus, The Process: The Methodology, Philosophy & Principles of Coaching Winning Teams.

This kind of approach is based on the following components:

1. Preparedness – The underlying long-term adaptations that have occurred for the player, such as overall strength, power, speed, endurance, and other qualities based on previous experiences and training exposure. This requires knowledge of the player’s sport involvement and training history and how it affects what must be done during in-season practice and training interventions.
2. Readiness – How well the player’s body is functioning at the current moment. Readiness must be high upon entering game day and must be maximized as much as possible for important conference games or championship games. Improper training and practice interventions will disrupt player readiness and game day performance.
3. Psychological Resilience – The player’s ability to cope with mental stressors associated with high levels of competition. Practice and training sessions have an impact on a player’s psychology, as physiology is largely intertwined with a player’s mental state and one will impact the other.

During a competitive season, a coach must keep these three components front of mind. Most team sports play at least one game each week, and some upward of three or more depending on the time of year. The game itself is the most important testing protocol for sports performance, meaning that sports practice becomes the most important training session.

The game itself is the most important testing protocol for sports performance, meaning that sports practice becomes the most important training session. Share on X

In terms of physical preparation, it becomes about winning small battles. So, there is no answer as to how to progress the training; there is only a necessity to be aware of potential training effects and the insurance that what is imposed on the players aligns properly with what is happening in practice on the road to game day.

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References

1. Bogdanis, G. C., Tsoukos, A., Kaloheri, O., Terzis, G., Veligekas, P., and Brown, L. E. (2019). “Comparison Between Unilateral and Bilateral Plyometric Training on Single-and Double-Leg Jumping Performance and Strength.” The Journal of Strength and Conditioning Research, 33(3), 633–640.

2. Boyle, M. (2011). Advances in Functional Training. Lotus Publishing.

3. Cappa, D. F. and Behm, D. G. (2011). “Training specificity of hurdle vs. countermovement jump training.” The Journal of Strength and Conditioning Research, 25(10), 2715–2720.

4. Dietz, C. and Peterson, B. (2012). Triphasic Training: A Systematic Approach to Elite Speed and Explosive Strength Performance (Vol. 1). Bye Dietz Sport Enterprise.

5. Edwards, T., Spiteri, T., Piggott, B., Haff, G. G., and Joyce, C. (2018). “A narrative review of the physical demands and injury incidence in American football: application of current knowledge and practices in workload management.” Sports Medicine, 48(1), 45–55.

6. Francis, C. (1997). Training for Speed. Faccioni.

7. Issurin, V. (2008). Block Periodization: Breakthrough in Sports Training. Ultimate athlete concepts.

8. Jeffreys, I. and Moody, J. (Eds.). (2016). Strength and Conditioning for Sports Performance. Routledge.

9. Lockie, R. G., Callaghan, S. J., Berry, S. P., Cooke, E. R., Jordan, C. A., Luczo, T. M., and Jeffriess, M. D. (2014). “Relationship between unilateral jumping ability and asymmetry on multidirectional speed in team-sport athletes.” The Journal of Strength and Conditioning Research, 28(12), 3557–3566.

10. Maloney, S. J., Richards, J., Jelly, L., and Fletcher, I. M. (2019). “Unilateral stiffness interventions augment vertical stiffness and change of direction speed.” The Journal of Strength and Conditioning Research, 33(2), 372–379.

11. McLellan, C. P., Lovell, D. I., and Gass, G. C. (2011). “Biochemical and endocrine responses to impact and collision during elite rugby league match play.” The Journal of Strength and Conditioning Research, 25(6), 1553–562.

12. Ramírez-Campillo, R., et al. (2015). “Effect of unilateral, bilateral, and combined plyometric training on explosive and endurance performance of young soccer players.” The Journal of Strength and Conditioning Research, 29(5), 1317–1328.

13. Verkhoshansky, Y. and Siff, M. C. (2009). Supertraining. Verkhoshansky SSTM.

14. Verkhoshansky, Y. and Verkhoshansky, N. (2011). Special Strength Training: Manual for Coaches (p. 274). Rome: Verkhoshansky SSTM.

15. Wellman, A. D., Coad, S. C., Goulet, G. C., and McLellan, C. P. (2017). “Quantification of accelerometer derived impacts associated with competitive games in National Collegiate Athletic Association Division I college football players.” The Journal of Strength and Conditioning Research, 31(2), 330–338.