The Effect of Core Training on Athletic Performance

In this literature review, the question, “What is the effect of core training on athletic performance?” will be explored to see if core training really does improve an athlete’s performance. This is a widely discussed area in sport and is well studied. Personal trainers talk about “training the core”, but what they are usually referring to is just the abdominal muscles which is incorrect. The “core” is the area below the pectoral muscles, down to and including the hips. This is the area from which the body stabilises itself, so its extremities - such as arms, head and legs - can move efficiently. A strong core means stronger arms and legs which will improve any movement whether it is running, jumping, throwing etc. The literature's reviewed range from 1992 and 2014.

The core can be scientifically defined as “the trunk or more specifically the lumbo-pelvic region of the body” (Willardson 2007). Most people misinterpret the meanings of core stability and core strength. Core stability means “The ability to control the position and motion of the trunk over the pelvis to allow optimum production, transfer and control of force and motion to the terminal segment in integrated athletic activities” (Kibler. 2006, Lawrence 2007, Willson JD, Davis 2005). A stable core prevents the body moving into incorrect planes of motion such as having an anterior pelvic tilt and will prevent any injuries in the trunk area.

Core strength can be defined as “the muscles surrounding the spinal column’s ability to maintain stability while acting on an external perturbation” (Hibbs 2008, Akuthota, Nadler 2004). When completing either strength training, endurance training or stability training, we are making the core more efficient at these roles.

Core training has two key roles: -

“1/ the first role is protecting (stabilizing) the spine from excessive (and potentially injurious) forces.

2/ the second is in the creation and transfer of forces in a proximal to distal sequence” (Brumitt, 2010, Panjabi,1992)

In theory the effect of core training on athletic performance for either a power based sport or an endurance based sport, should improve performance. The reasons we need to have a strong core is because the core is the base for all movements our body makes. When we throw, push, pull or jump, the core is always involved to give the body a stable base to work off. A stronger core increases the strength/power/endurance capabilities of the upper and lower extremities. Mark Rippetoe further confirms that the core is used for transferring power/force to the extremities (Rippetoe, 2009).

In this literature review we will be looking at the effect of core training in NFL (National Football League) players (power/strength sport) and comparing their results with 5000m runners results (endurance sport).

 “The Relationship between Core Stability and Performance in Division 1 Football Players” Nesser, TW, Huxel, KC, Tincher, JL, and Okado, T. (2008)

 “Does Core Strength Training Influence Running Kinetics, Lower Extremity Stability and 5000m Performance in Runners”.  Kimitake. S, Monique. M (2009)

These are diverse sports, each of which requires different skills and different components of fitness. NFL requires more strength and power which relies heavily on the ATP-PC energy system, whereas the 5000m runners rely upon muscular endurance and aerobic capacity to complete their task. However, the common denominating factor is that both of these sports need a strong and efficient set of core muscles to carry out their prescribed sporting demands.

Credit: https://keithclinic.com/posts/exercise-tips/core-strength-beyond-the-six-pack/ 

Reviewing these studies, both sets of subjects improved their performance - one group minimally and one group significantly. The 5000m metre study showed that during the testing, the CST (Core Strength Training) group had a significant improvement in 5000m times after 6 weeks of implementing their core training intervention. It should be mentioned CST did not significantly influence GRF (Ground Reaction Force) variables and lower-leg stability. The CST group average time improved by 47 seconds and the control group improved by 7 seconds on average. There were minimal differences in pre and post climates for the 5000m tests performed. The main difference between the pre and post was the introduction of the core strengthening programme and increase in training volume/intensity. It could be theorised that the introduction of this core training may have influenced the results (Kimitake, Monique 2009).

The NFL study showed that with core training, their athletes’ performances only improved marginally. The results of this study indicated that core stability is moderately related to the strength and performance of the athlete. They concluded that “increases in core strength are not going to contribute significantly to strength and power improvements and should not be the focus of the strength and conditioning” (Nesser, Huxel, Tincher, Okado, 2008).  The aim of this study was to “determine whether core strength is related to more specific measurements of strength and power in strength and power athletes”. The 29 male athletes were tested during their pre-season. The independent variables which were used to measure the athletes’ core strength/stability included back extension, trunk flexion, right and left side bridge. The dependent variables are the 1RM (one repetition maximum), CMJ (Countermovement Vertical Jump), Pro Agility Shuttle Run, 20 yard and 40 yard Sprints.

Reviewing both studies highlighted certain limitations. In the 5000m study the data for both the GRF groups were affected by inconsistent running velocity due to the subjects not following experimental protocol which resulted in inaccurate pre and post-test times. Subjects ran faster post-test but were instructed to run at same speed (at a natural pace) pre-test for a more reliable and valid comparison between pre and post training GRF tests. However, especially within the CST group, its subjects ran faster during the post training GRF test (Kimitake, Monique 2009). This improvement, specifically in the CST group, may be due to the subjects putting more effort in and possibly manipulating results - this is described as the Hawthorn Effect. This is known as “Participant’s performance changes when attention is paid to them, which is likely to reduce the ability to generalize the results” (Thomas, Nelson, Silverman, 2011). This enhancement will have affected the internal validity of the study due to the subjects not following the specific instructions. The Hawthorn Effect may have been present in this study as they were testing themselves to try and improve their own scores. Their study does mention the enhancement in the results which includes the factor of “test/re-test”.

It could be summarised that the internal validity is affected more as the subjects were given a second attempt to improve their 5000m times. This led to a noticeable difference in temperature, pre =86 F (Fahrenheit), 64% humidity; post=73 F, 58% humidity (Kimitake, Monique 2009). Running in a hot environment makes the body work harder as it has to sweat more to keep the body cool and this excessive sweating costs the body lots of sodium and energy. Endurance training in hot environments will decrease in performance over time (Armstrong 1986, Neilsen 2003, Nybo 2004, Lepage 2011). Another factor which may have affected the results is the body shape and mass of the runners. The control group were slightly heavier than the experimental group so their times would have been slower on average when compared. However internal validity is verified as the subjects were randomly allocated in this study.

Credit: https://www.studyblue.com/notes/note/n/trunk-muscles/deck/16843955 

When analysing the results of the NFL study, they are not consistent. It can be seen that there is too much variance around the mean as shown from Table 2 below.

Having a large variance around the mean of results reduces the validity and reliability of the study.

(Nesser, Huxel, Tincher, Okado, 2008). 

The study incorporated McGill’s core stability tests which are taken from his own study which was solely to find and “collect isometric endurance times from a healthy normal population performing the "side bridge" or lateral flexion exercise, as well as isometric flexion and isometric extension exercises”. These endurance times can be used to form "normal" relative ratios to guide clinicians and identify endurance deficits within specific patients” (McGill, 1999).

Dr Stuart McGill. Image Credit: https://kabukistrength.com/category/articles/dr-stuart-mcgill/ 

However, there is a major limitation using McGill’s testing methods as McGill was testing for a different component of fitness i.e. Muscular Endurance and in Nesser’s study he is applying these tests to power and strength athletes. Using a test aimed at endurance then comparing it to tests of 1RM, CMJ, Agility Testing and 20/40 yard will not produce a significant difference in pre and post test results. With using an inappropriate method of testing and the study’s own results being inconsistent we can conclude that the “The Relationship between Core Stability Training and Performance in Division 1 Football Players” isn’t reliable to determine if core training has an impact on power/strength athlete’s performance.

However, this doesn’t mean that core training won’t have any benefit for strength/power based athletes. As shown from the Kata Karate study, their performance improved (Sameh, Tantawi 2011). Looking at Justin Shinkle’s study the Effect of Core Strength on the Measure of Power in the Extremities – it states that “Core strength does have a significant effect on an athlete’s ability to create and transfer forces to the extremities” (Shinkle 2012). Strength and power athletes such as powerlifters and weightlifters, may not need to do specific core exercises as they are always using their core muscles for their sport (squats, cleans, snatches). In theory, their core stability is constantly improving as they are constantly engaging their core.

Another point of note from the 5000m study, is that the CST group became more aware of their posture when running, which in turn may have contributed to a better post-test result. When asked for their feedback the subjects were more conscious of their core muscles to stabilize themselves when running (Kimitake, Monique 2009). The study did state that their own work may have produced this improvement due to more training sessions compared to others which only did 2 sessions per week over a 6 week period. A higher training volume is needed to increase core strength which may have improved 5000m running times post-test (Kimitake, Monique 2009). This again brings in the Test Re-Test Effect and Hawthorn Effect.

It has been proven that better posture when running does improve biomechanics which in turn improves performance through more efficient running mechanics as shown from numerous studies such as “The Effects of Posture on Running Performance: A Case Study” (Comereski, Niedzielski 2004). These results showed that by doing postural repositioning exercises over a 5 week period, the performance of the track athlete improved. Postural repositioning focused on getting the pelvis into a neutral position, stretching the lower back muscles, strengthening the weaker core muscles such as obliques - this led to an improvement in performance. Improvement was shown from a 14 second improvement over 1 mile and 6 second improvement over the 800m.The main limitations for this study are that it was only performed on one individual.

To summarise all the literature reviewed, it could be postulated that core training is important for all athletes but it has more significance for those athletes who partake in endurance events. This is supported from the 5000m study by Kimitake, Monique 2009. It could be theorised that endurance sports utilize the core muscles to a greater extent and for a longer period. This is evidenced as core training has significantly more of an impact on endurance athletes than power/strength athletes. It could be argued that whilst competing in endurance events, these core muscles are being used for longer and have a greater stress placed upon them - especially the diaphragm muscles when breathing. The abdominals need to be very strong and energy efficient to help improve an athlete’s ventilation ability (increase rate and depth of breaths).

Credit: https://eu.azcentral.com/story/news/local/arizona-best-reads/2017/05/11/how-tiny-fiber-implant-research-spinal-cord-injuries-neuro-spinal-scaffold/309193001/ 

Looking at the demands of the core muscles on an NFL athlete, they need to be able to contract and relax quickly to produce a large amount of force/power and be able to stabilize itself when releasing this force upon or towards an object. This happens for a few seconds and then stops. This “stop start” (interval) way of this sport, doesn’t require their athletes to place a huge significance onto core training. Perhaps NFL could focus more on compound movements to improve their performance such as squats, deadlifts, cleans etc which works the whole body and engages the core muscles in a way that has a positive effect towards their sport.

In conclusion, analysis and comparison shows that the results from the 5000m study shows very positive data (such as 47 second improvement). However, the NFL study is significantly different, as their athletes minimally improved. This could be due to different testing procedures, internal/external variables influencing the data and different subjects for each group having their own individual effects on the data collection.

When compared to the power/strength studies of NFL their performances did improve but not to the same extent as the 5000m runners. The NFL subjects improved marginally on their strength/power tests after their core intervention. The NFL evidence is flawed due to the testing methods, as the study used endurance tests exercise programme.

In future research regarding the topic of core training, practitioners should devise a core test protocol which is generic and then create sport specific core tests relevant to strength and conditioning core training programmes for their athletes. Core training is still a developmental part of sports science today as we are still learning how it can be most effective and applicable to different sports.

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References

1.    Akuthota V, Nadler SF. (2004) “Core strengthening”. American Academy of Physical Medicine and Rehabilitation; 85 (3 Suppl. 1): S86-92

2.    Armstrong LE,Hubbard RW, JonesBH, et al. (1986) “Preparing Alberto  Salazar for the heat of the 1984 Olympic Marathon”. Phys Sportsmed. 14 (3): 73-81

3.    Brummit, J., (2010). Core Assessment and Training, USA, Human Kinetics

4. Comereski.S.J, Niedzielski. M. (2004) “The Effects of Posture on Running Performance: A Case Study”. American Medical Athletic Association Journal Spring 2004

5.    Hibbs AE, Thompson, K. G., French, D., Wrigley, A., Spears, I. (2008) “Optimizing performance by improving core stability and core strength”. Sports Medicine, 38(12):995-1008.

6.    J.M.Willardson (2007) “Core Stability Training: Applications to Sports Conditioning Programs”. Journal of Strength and Conditioning Research 21 (3) 979-985

7.    Kibler, W., Press. J, Sciascia. A (2006). “The Role of Core Stability in Athletic Function”. Sports Medicine, 36(3): 189-198.

8.    Kimitake. S, Monique. M (2009) “Does Core Strength Training Influence Running Kinetics, Lower-Extremity Stability, and 5000-M Performance In Runners?” Journal of Strength and Conditioning, 23 (1) 133.

9.    Lawerence, M. (2007). Core Stability.  2^nd Edition.  , London, A&C Black Publishers Ltd.

10. Lepage.W, (2011) Optimum Temperature for Elite Running Performance http://runjeffcity.org/optimum-temperature/. Accessed February 15^th 2014

11. McGill, SM, Childs, A, and Liebenson, C. (1999) “Endurance times for low back stabilization exercises: clinical targets for testing and training from a normal database”.  American Academy of Physical Medicine and Rehabilitation 80: 941–944, 1999.

12. Nesser, TW, Huxel, KC, Tincher, JL, and Okado, T. (2008) “The relationship between core stability and performance in Division I football players”. Journal of Strength and Conditioning Research 22(6):1750–1754

13. NIELSEN. B., and L. NYBO. (2003) “Cerebral changes during exercise in the heat”. Sports Med. (New Zealand) 33:1–11.

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15. Panjabi M. (1992) “The Stabilising System of the Spine, Part I: Function, Dysfunction, Adaptation and Enhancement”. Journal of  Spinal Disorders and Techniques; 5 (4): 383-9

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17. Sameh Sh. Tantawi, (2011) “Effect of Core Stability Training on Some Physical Variables and the Performance Level of the Compulsory Kata for Karate Players”

18. Shinkle, J, Nesser, TW, Demchak, TJ, and McMannus, DM. (2012) “Effect of Core Strength on the Measure of Power in the Extremities”. Journal of Strength and Conditioning Research 26(2): 373–380

19. Thomas. J, Nelson. J, Silverman. S (2011) Research Methods in Physical Activity. 6^th Edition. Stanningley: Human Kinetics p335

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Andrew Richardson, Founder of Strength is Never a Weakness Blog

I have a BSc (Hons) in Applied Sport Science and a Merit in my MSc in Sport and Exercise Science and I passed my PGCE at Teesside University. 

Now I will be commencing my PhD into "Investigating Sedentary Lifestyles of the Tees Valley" this October 2019. 

I am employed by Teesside University Sport and WellBeing Department as a PT/Fitness Instructor.  

My long term goal is to become a Sport Science and/or Sport and Exercise Lecturer. I am also keen to contribute to academia via continued research in a quest for new knowledge.

My most recent publications: 

https://www.sciencedirect.com/science/article/pii/S1752928X19300216

https://www.sciencedirect.com/science/article/abs/pii/S1752928X19301076 

My passion is for Sport Science which has led to additional interests incorporating Sports Psychology, Body Dysmorphia, AAS, Doping and Strength and Conditioning. 

Within these respective fields, I have a passion for Strength Training, Fitness Testing, Periodisation and Tapering. 

I write for numerous websites across the UK and Ireland including my own blog Strength is Never a Weakness. 

I had my own business for providing training plans for teams and athletes. 

I was one of the Irish National Coaches for Powerlifting, and have attained two 3rd places at the first World University Championships, 

in Belarus in July 2016.Feel free to email me or call me as I am always looking for the next challenge. 

Contact details below; 

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