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When it comes to most competitive sports, speed and strength are two of the most sought-after physical qualities in athletics. Funnily enough these qualities have traditionally been trained independently of each other, despite being closely related1.

Force Important But Not Be All and End All

The force an athlete is able to apply to the ground determines how fast he or she can run, how quickly he or she can change direction and how high he or she can jump – all important variables for performance on the playing field. However, the road to athletic success unfortunately is not as simple as being strong as Popeye. It's the amount of force that can be applied in a given time that counts.

Constraints of Force Development

On the playing field, athletes don’t have the luxury of unlimited time to generate what little or great strength they possess. Research has determined that it takes at least 0.3 to 0.4 seconds to reach maximum force levels2. But the average time taken to complete a maximal squat or deadlift movement is roughly 0.6 seconds3. This is at odds with the time available to produce force during track and field events involving running and jumping, where force has to be produced in 0.1 to 0.2 seconds4-6.

Rate of Force Development

So on the playing field it’s easy to see that strength is not the sole determinant of optimal force output. Rather it is the rate of force development that is much more important that strength alone. And this is the precise physical attribute that variable resistance training is thought to improve.

Limitations of Free Weights for Power Development

The drawback with conventional weight training is it may be great for increasing strength in your average gym junkie, but that same individual may be severely deficient in their ability to generate force quickly7, 8.

Traditionally, resistance training programs for athletes engaged in track and field or competitive sports have simply instructed athletes to move an external resistance as fast as possible to achieve improvements in their rate of force development. But a major drawback with this approach is that a large portion of the movement range is spent decelerating the resistance9-14.

Variable Resistance Training

Variable resistance training is a new type of weight training used increasingly in strength and conditioning programs that incorporates the use of resistance/elastic bands. By aligning resistance bands with the plane of movement, the athlete can use his or her mechanical advantage to simultaneously generate high force and high power levels in selected training movements applicable to their given sport15-17.

Resistance bands have traditionally been used in the realm of rehabilitation from sports injuries. However, there is a wide body of scientific literature which now points to their utility for increasing power in athletes. As pictured below, resistance bands are commonly used in conjunction with free weights so as to provide a variable resistance/load throughout a given movement. Herein lies the reason why this type of training is often referred to as variable resistance training.

Bench press with resistance bands

Theory of Variable Resistance Training

The theory of variable resistance training suggests that increased muscle activation occurs throughout the concentric phase of a given movement as a result of the progressively increasing resistance the athlete has to overcome.

Put another way variable resistance training allows an athlete to optimally load muscles throughout the range of motion by using the mechanical advantage of muscles15-17. This mechanical advantage is largely a product of the length–tension relationship of skeletal muscle18. Variable resistance training is believed to take advantage of this length–tension relationship by allowing for increased muscle activation through the concentric portion of the BSE19.

Variable resistance training also increases force during the later phases of the eccentric portion of the lift because the added tension toward the end of the concentric phase requires increased force to finish the lift; and extra force is required toward the end of the eccentric phase to slow the weight because of the added band tension in addition to the weight plates pulling the barbell downward in the early phases of the eccentric phase6.

Load vs Weight in Variable Resistance Training

The issue of the load versus the weight on a muscle through a given range of motion is important when discussing the virtues of training with resistance bands. This is because of the length-tension principle which dictates that muscles are more mechanically advantaged/disadvantaged at certain positions within a movement4.

For example, in the case of the traditional squat, the most advantageous position is near the top of the squat with knees near full extension, while the most mechanically disadvantaged position is at the bottom of the squat where legs are bent at approximately 90 degrees.

As depicted in the pictures below, the use of resistance bands allows the load to progressively lighten during the downward (eccentric) movement. This means the load at the beginning of the concentric phase is less, thus allowing the athlete to achieve higher accelerations early in the movement.

box squat standing w resistance bands

box squat bent w resistance bands

As the resistance bands stretch during the concentric movement, the athlete is required to continue recruitment of high threshold motor units resulting in an increase in force production at higher speeds. This pattern of acceleration during the concentric phase is thought to translate into greater power production at or near full limb extension20, 21.

Division of Weight/Load Between Free Weights and Resistance Bands

An important aspect of variable resistance training concerns how weight is divided among free weights and resistance bands. Studies have reviewed this topic and concluded that the total unit load (including free weight mass and resistance bands load) should be between 60 and 85% of an athlete’s 1RM, of which 20-30% of total load is mass provided by elastic tension22. While researchers have developed sophisticated tools to measure the load exerted by different sized elastic resistance bands, the average individual has to rely on the manufacturer’s directions concerning the typical weight range provided by a given band.

Benefits of Variable Resistance Training for Novice Athletes

While the most common application of variable resistance training is to provide added resistance throughout a movement, the reverse is also true. The picture below shows an example of a resistance-band assisted squat.

resistance band assisted loaded squat

Using resistance bands to provide variable assistance across a range of exercises can be useful for training novice and/or weaker athletes especially during rehabilitation from injury. Resistance bands can be used to reduce bodyweight or external loads through sticking points, allowing the individual to focus on control and stability throughout a movement’s range of motion.

Using resistance bands to provide assistance is commonly employed in advanced-level competitive athletes to enhance force production, speed of movement. An example of sports that use this approach are teams sports such as rugby union, football, Australian Rules Football and rugby league. Using resistance bands to provide assistance is thought to reduce the overall load (including CNS) on the body, while still focusing on the speed component of power, which is an effective peaking strategy before game day or competition23.

Sample Weight Training Program Using Variable Resistance

So how might a competitive athlete engaged in team sports incorporate variable resistance training into their strength and conditioning regime? The sample program below comes from a recent study published in the Strength and Conditioning Journal and written by two prominent researchers in the field from New Zealand’s High Performance Sport centre23. This particular program was suggested as an option for Rugby 7s players and it incorporates both resistive and assistive modalities of variable resistance training.

Session 1

Session 2

Week 1


Resisted 5 x 5 at 80-85% 1RM (10% total load from elastic bands)

Assisted 5 x 3 at 80-85% 1RM (10% total load from elastic bands)

Week 2


Resisted 5 x 5 at 80-85% 1RM (20% total load from elastic bands)

Assisted 4 x 3 at 80-85% 1RM (20% total load from elastic bands)

Week 3


Resisted 5 x 5 at 80-85% 1RM (30% total load from elastic bands)

Assisted 3 x 3 at 80-85% 1RM (30% total load from elastic bands)

1RM = 1 repetition maximum


Variable Resistance Training Reduces Momentum

Many of the proven benefits of combining resistance bands with free weights can be summarised in the fact that they help reduce the momentum that occurs when using free weights exclusively. The physics of resistance training with free weights dictates that the force required to get the weight moving is not the same as the force required to keep the weight moving, due to the momentum generated by the weight.

This is a problem as far as muscle activation is concerned because as the degree of momentum increases, the degree muscle activation decreases. The ability to provide increasing load throughout the concentric movement is key to increased muscle activation, which is thought to underpin much of the superior power development seen when combining resistance bands with free weights. Training only with free weights may not allow an athlete to express their full power potential due to momentum.

Same Load – Less Weight

The key message with resistance bands is that they allow one to use an equivalent load to free weights, with the exception that it comprises less mass. This in turns allows for greater acceleration even when using an equivalent force required to lift the same load in free weights alone. And as many strength and conditioning coaches will attest…speed is power! As such, resistance bands offer the strength and conditioning coach an opportunity to exploit a range of mechanisms that cannot be provided through traditional resistance training using free weights alone.


  1. Baker, D. Selecting the appropriate exercises and loads for speed and strength development. Strength Cond Coach 3: 8–16, 1995.
  2. Rhea MR, et al. A comparison of linear and daily undulating periodized programs with equated volume and intensity for strength. J Strength Cond Res 16: 250–255,2002.
  3. Elliot BC, et al. A biomechanical analysis of the sticking region in the bench press. Med Sci Sports Exerc 21: 450–462, 1989.
  4. Heinecke M, et al. Comparison of strength gains in variable resistance bench press and isotonic bench press. Journal of Strength and Conditioning Research. 2004;18:e10.
  5. Newton RU, et al. Kinematics, kinetics, and muscle activation during explosive upper body movements: Implications for power development. J Appl Biomech. 1996;12:31–43.
  6. Wallace BJ, et al. Effects of elastic bands on force and power characteristics during the back squat exercise. Journal of Strength Conditioning Research. 2006;20:268–272.
  7. Garhammer, J. A review of power output studies of Olympic and powerlifting: Methodology, performance, and evaluation tests. Journal of Strength and Conditioning Research. 1993;7:76–89.
  8. Newton RU, et al. Heavy elastic bands alter force, velocity and power output during back squat lift. Journal of Strength and Conditioning Research. 2002;16:1-18.
  9. Cronin JB, et al. Force-velocity analysis of strength training techniques and load: Implications for training strategy and research. J Strength Cond Res. 2003;17:148–155.
  10. Elliot BC, et al. A biomechanical analysis of the sticking region in the bench press. Med Sci Sports Exerc. 1989;21:450–462.
  11. McGinnis, PM. Biomechanics of Sport and Exercise. Champaign, IL. Human Kinetics, 1999. p. 358.
  12. Newton RU, et al. Kinematics, kinetics, and muscle activation during explosive upper body movements: Implications for power development. J Appl Biomech. 1996;12:31–43.
  13. Newton RU, et al. Heavy elastic bands alter force, velocity, and power output during back squat lift. J Strength Cond Res. 2002;16:13.
  14. Zatsiorsky, VM. Science and Practice of Strength Training. Champaign, IL. Human Kinetics, 1995. pp. 35037, 202–205.
  15. Ariel, G. Variable resistance versus standard resistance training. Schol Coach. 1976;46:68–69.
  16. Ebben, WP and Jensen, RL. Electromyographic and kinetic analysis of traditional, chain, and elastic band squats. J Strength Cond Res. 2002;16:547–550.
  17. Verkoshansky, YV. Fundamentals of Special Strength Training in Sport. Livonia, Michigan: Sportivny Press, 1986. pp. 25–28, 181.
  18. Elliot BC, et al. A biomechanical analysis of the sticking region in the bench press. Med Sci Sports Exerc. 1989;21:450–462.
  19. Rhea MR, et al. Alterations in speed of squat movement and the use of accommodated resistance among college athletes training for power. Journal of Strength and Conditioning Research. 2009;23(9):2645-2650.
  20. Anderson CE, et al. The effects of combining elastic and free weight resistance on strength and power in athletes. Journal of Strength and Conditioning Research. 2008;22:567-574.
  21. Frost DM, et al. A biomechanical evaluation of resistance: Fundamental concepts for training and sports performance. Sports Medicine. 2010;40:303-326.
  22. McMaster DT, et al. Forms of variable resistance training. Journal of Strength and Conditioning Research. 2009;31:50-64.
  23. Wilson J & Kritz M. Practical guidelines and considerations for the use of elastic bands in strength and conditioning. Strength and Conditioning Journal. 2014;36(5):1-9.
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