The theory and practice of developing strength that can be transferred onto the track.

In 2013, Athletics Australia hosted a sprinting conference with the internationally respected Dutch coach, Henk Kraaijenhof. One of the key messages taken from his presentation was the challenge of transferring strength gained from the gym into improved performance on the track. Those back squats might be making your athlete a better lifter and it’s certainly making them look stronger, but is this extra muscle actually transferring to improved 100m times? What can the coach do to ensure that the time the athlete is spending in the weights room is being used most effectively for performance gains?

Key Principle: Strength is Specific

The ‘Specific Adaptation to Imposed Demand’ or ‘Specificity’ principle suggests that strength gains are greatest when tested using the same characteristics as the training program

Strength is specific in a number of different ways and this should determine how and what we train. To maximise the transfer between ‘weight room strength’ and the specific strength required for sprinting, coaches need to ensure that their chosen exercises best replicate the unique conditions of sprinting. This article will examine how the velocity, muscle group, muscle action, direction of force and joint angle of the muscles trained will effect the training outcomes and how these factors can be manipulated to maximise training outcomes for sprinting performance.

How is Strength Specific?

1. Velocity - Speed of Movement

The Principle

Training exercises that are performed at a high velocity will lead to proportionally greater gains in high velocity strength. For example, exercises that are performed at high speed such as hang snatches (see example video) will theoretically lead to a proportionally greater improvement in an athletes ability to perform high velocity exercises than exercises performed at low velocity (Ayers et al., 2016).

The Evidence

Coyle et al. (1981) provided the foundation of practical evidence to support the relationship between velocity of training and specific strength outcomes. The study tested athletes who trained using knee extensions for six weeks using either a slow (60 degrees/s) or a fast (300 degrees/s) technique. The results showed that participants from the slow treatment group had proportionally greater strength gains at low velocity and those from the fast treatment group had proportionally greater high velocity strength gains.

Interestingly, the slow treatment group only showed minimal improvement of high velocity strength, whereas training at faster speeds did also result in an improvement of low velocity strength, although signficantly less than the slow treatment group (Figure 1).

The velocity-specific nature of strength has since been supported by a host of studies that have demonstrated it is true for single-joint exercises (Moss et al., 1997; Ingebrigtsen et al., 2009), multi-joint exercises (Mora-Custodio et al., 2016) and in trained (Aagaard et al., 1994) and untrained athletes (Moss et al., 1997).

The Sprinting Implication

Sprinting is primarily a high velocity action, so strength training at high speeds should result in greater improvement of sprinting performance than training at lower speeds. A longitudinal study by Loturco et al. (2015) supported this hypothesis, demonstrating that a high velocity strength program resulted in proportionally a greater improvement in 5, 10 and 20 metre sprint times compared with a lower velocity training program.

The Coaching Application

The velocity that an exercise is performed can be manipulated using the following methods:
• Reducing the weight of the training implement. There is some evidence to suggest that exercises conducted between 40 and 60 percent of the athlete’s 1RM are the most effective for improving high velocity strength and improving sprinting performance (Young, 2006; Thomas et al., 2007; Mora-Custodio et al., 2016).
• Intent to produce force quickly. There is some evidence to suggest that the actual speed of the action is less important than the cognitive intention of the athlete. That is to say, there will be an improvement in high velocity strength when the athlete intends to perform training at maximal velocity, regardless of the actual movement speed (Behm & Sale, 1993). See Balshaw et al. (2016) for an excellent explanation of the proposed neural factors involved in this.

Young (2006) also advises that sprinters will also still benefit from a general non-specific resistance program and that a sprinter’s program should include more than exclusively high-velocity exercises. General resistance training is likely to aid injury prevention and facilitate the development of high velocity strength.

2. Muscle Group - Prioritise Hip Extensors, Hip Flexors, and Knee Flexors

The Principle

It is well understood that strength gains are specific to the groups of muscle that are being stressed. Athletes must incorporate a range different exercises to develop the range of muscles that contribute to sprinting performance (Gonyea et al., 1986; Rogers & Evans, 1993).

The Sprinting Implication

Understanding the most important muscles for sprinting performance will assist athletes and coaches to prioritise training of the muscle groups that are most important for sprinting success.

The Evidence

The current evidence suggests that the hip extensors, hip flexors and knee flexors are the most important muscle groups for sprinters. A comparison between the strength of elite sprinters and the general public demonstrated that sprinters tended to have overall greater muscle mass than the average individual, but had proportionally even greater strength in their hip extensors, flexors and knee flexors (Handsfield et al., 2016 - Figure 2).

Hip Extensors (esp. Semitendinosus, Gluteus maximus) Mann & Hagy (1980) demonstrated that sprinting ability improved with greater hip extensor strength and this has since been supported by further studies that have examined the relationship between the two (Belli, Kyrolainen & Komi, 2002; Young, 2006; Beardsley & Contreras, 2014).

Electromyographic analysis of the sprinting action has suggested that the hamstrings may have the greatest increase in muscle activation as running speed increases, suggesting that they may be an important driver of running velocity (Kyrolainen et al., 2005).

Hip Flexors (esp. Psoas major, Rectus femoris) The size of an athlete’s psoas major has been shown to be correlated to their sprinting ability (Copaver, Hertogh & Hue, 2013) and has been shown to be an important muscle for increase stride frequency during sprinting (Dorn et al., 2012). Evidence has shown that a hip flexion program can improve 10-yard and 40-yard sprinting times (Deane et al., 2005).

Knee Flexor (Hamstring group) The hamstrings are also an important muscle group for knee flexion, which is believed to contribute to sprinting performance (Mann & Hagy, 1980), especially during the late swing and early stance phase (Jonhagen et al., 1996).

The Coaching Application

As strength is specific, exercises that develop the strength of the hip extensors and flexors should be prioritised. The following exercises have been recommended by strength and conditioning experts for sprinters looking to build strength in these muscle groups.

Nordic Hamstring Curls
See this article for more.

Barbell Glute Bridge
See this article for more.

Hip Thrusts
See this article for more

Trap Bar Deadlift Jump
See this article for more

Kettlebell Swings
See this article for more

Resisted Hip Flexion
See this article for more

Single Leg Romanian Deadlift
See this article for more

Lying Leg Curl
See this infographic for more

What about the Quadriceps?
A study by Miyake et al. (2017) tested the difference in the cross-sectional area of the quadriceps between sprinters and non-sprinters. The results demonstrated that there was not a significant difference in the size of the quadriceps muscles between sprinters and non-sprinters, suggesting that the muscle group is not a signficant contributor to sprinting success. The researchers also found a lack of correlation between the size of an athlete’s quadriceps and their reported personal best time over 100 metres. This finding was supported by Bex et al. (2016) who found that a greater hamstring:quadriceps ratio was correlated with faster sprinting performances.

However, it should be noted that Handsfield et al.’s (2016) study found that the rectus femoris to be one of the proportionally largest muscles in elite sprinters compared with non-sprinters, suggesting that further research is required before we fully understood the importance of this muscle group for sprinters.

3. Muscle Action- Eccentric and Concentric

The Principle

Strength is specific to the muscle action that is being trained. Eccentric training produces proportionally greater gains in eccentric strength and concentric training produces proportionally greater gains in concentric strength (Vike et al., 2006).

The Sprinting Implication

Biomechanical analysis of the sprinting action demonstrates that sprinting requires concentric strength in the hip flexors and hip extensors and eccentric strength in the knee flexors (Hunter et al., 2005; Chumanov et al., 2011).

Coaches should consider implementing an eccentric-specific training routine to ensure the athlete develops the required eccentric strength, especially in their hamstrings. While many common strength exercises include both an eccentric and concentric phase, an individuals’ eccentric 1RM is usually significantly greater than their concentric 1RM (Kelly et al., 2015). The implication of this is that exercises with both an eccentric and concentric phase are not developing the athlete’s eccentric strength to the same degree as it develops their concentric strength as the weight or number of repetitions is being limited by their concentric maximum.

The Evidence

de Hoyo et al. (2015) demonstrated that an eccentric-specific training program was an effective intervention for improving maximum running speed in junior football players in addition to assisting injury prevention. This has been supported by further studies that demonstrate that the development of eccentric strength using a plyometrics program has been effective for improving speed and acceleration (Rimmer & Sleivert 2000; Faigenbaum et al., 2007).

The Nordic Hamstring Curl has been found to be a more effective exercise for developing eccentric hamstring strength than traditional hamstring curls (Mjolsnes et al., 2004).

The Coaching Application

While the advantages of including concentric and eccentric-specific exercises for sprinting performance and assisting injury prevention have been well documented, there is little peer-reviewed evidence to support an optimal program for sprinters. Mjoslnes et al. improved their participant’s eccentric knee flexor strength using the Nordic Hamstring Curl program detailed in table to the right.

Strength and conditioning expert Chris Brearley recommends implementing two sessions of eccentric-specific exercises per week out of season (alternating between Nordic Hamstring Curls and Flywheel Leg Curls) and one session per week in-season.

Bret Contreras recommends that the Nordic Hamstring Curl be conducted with a resistance band that allows the athlete to control the movement throughout the full range of motion. When the majority of athletes attempt the motion you will notice that they lose control of the descent during the second half of the motion, whereas the resistance band will provide greater support as the athlete lowers themselves closer to the ground, ensuring that their muscles are active throughout the exercise.

4. Direction of Force

The Principle

Strength gains are specific to the direction of force generated in training. Exercises that generate force in a horizontal (anteroposterior) direction lead to proportionally greater gains in the ability to generate force in a horizontal direction.

The Sprinting Implication

Morin et al. (2012) and Kawamori et al. (2013) demonstrated that the ability to generate horizontal force is a key determinant of sprinting ability. While sprinting does require both horizontal and vertical generation of force (Weyand, 2010), the priority for the sprinter is likely to be training exercises which develop their ability to generate horizontal force. This is supported by Rabita et al. (2015) who found that the athlete’s ability to generate horizontal force was signficantly correlated with their sprinting performance.

The Evidence

The best evidence for the effectiveness of exercises generating a horizontal force vector for improving sprinting performance was a comparative study between the hip thrust and front squat by Contreras et al. (2017). The study found a significantly greater improvement in the hip thrust intervention group, supporting the theoretical evidence that horizontal force generation is the most important for sprinting performance.

The Coaching Application

The following table details the progression of hip thrusts that Contreras et al. used to improve sprinting performance.

There is also evidence to suggest that the inclusion of horizontal plyometrics can be effective for improving an athlete’s speed (Ozbar, Ates & Agopyan, 2004). The study used horizontal jumps, standing long jumps, front cone hops, and cone hops to improve speed.

5. Joint Angle

The Principle

Strength gains are specific to the range of motion that is being used in the exercise and gains in strength are proportionally greatest at the joint angle trained.

Bandy & Hanten (1993) and Murphy et al. (1995) tested the effects of isometric training at a knee angle of 30, 60 and 90 degrees. The results demonstrated that training at at 30 degrees resulted in the greatest increase in strength at shorter joint angles but no significant improvement at 90 degrees. Conversely, while the 90 degrees training group showed the greatest gains of strength at the trained joint angle, they also showed improvement in strength at all joint angles.

The Sprinting Implication

By examining the joint angles during the sprinting motion, we are able to gain an understanding of the sprinting-specific joint angle requirements. Studies by Gittoes and Wilson (2010) and Nagano et al. (2014) provide an understanding of the muscle lengths and joint angles at the various stages of the sprinting action. Based on this data, there is a theoretical benefit to training the gluteus maximus and rectus femoris at short lengths whereas the hamstrings would benefit from training at long and short muscle lengths.

The Evidence

Unfortunately, there appears to be limited evidence that directly tests the relationship between training at specific joint angles and the transfer to sprinting performance. The best evidence to support training at shorter muscle lengths comes from Rhea et al. (2016). This study compared the effects of quarter squat, half squat and full squat training program on the participant’s speed and jump height. The study found that the quarter squat treatment group resulted in the greatest improvement in speed and jumping height, consistent with what we know about the strength requirements of sprinting.

There is also evidence to support the requirement for hamstring strength at longer muscle lengths in sprinters. Jonhagen, Nemeth & Eriksson (1994) found that joint angle specific strength was important in determining the likelihood of injury in sprinters, with uninjured sprinters more likely to have greater strength at longer muscle lengths.

The Coaching Application

Including quarter squats and other glute and quadriceps exercises conducted at shorter muscle length are likely to be beneficial to sprinting performance. Conversely, Bloomquist et al. (2013) advocate for a diverse squatting program that incorporates squats at different ranges and speeds. The logic for this approach is that we know that exercises conducted at longer muscle lengths do improve strength at shorter muscle lengths (although proportionally less than short length exercises) but not vice versa. A sprinter may theoretically benefit more from a blended program where they develop greater general strength at all muscle lengths. The squatting progression used in their study is included on the table to the right.

Conclusion

By understanding the ways that strength is specific, we are able to design a strength program that results in a maximal improvement in performance. However, while this article explored some of the ways that strength is specific, it is by no means intended to be an exhaustive list of the way strength transfers to the unique requirements of sprinting. The challenge for you to take from this article is to think about the other unique strength requirements of sprinting and which exercises in the gym will transfer most effectively.

Supplementary Note on Coaching Young Athletes from Tudor Bompa PhD

“Even though laboratory research demonstrates that specificity training results in faster adaptation and leads to faster increments in performance, this does not mean that coaches and athletes have to incorporate specificity training from an early age. In this narrow approach to children’s sport, the only scope of training is achieving quick results irrespective of what may happen in the future of the young athlete...This is like trying to build a high-rise building on a poor foundation.”

Coaches of junior athletes should focus on developing general strength across a broad range of muscle groups, joint angles, speeds, and forces.

What exercises do you include in your strength programming? What is your rationale and objective? Share your experiences in the comments below.