Flexibility Research
Since CRC Flexibility* (UltraFLX) has been developed, it now differs from what I initially thought my system was being CRAC Contract-Relax-Antagonist-Contract. As explained earlier, the protocols I followed did not include a relax break during one of the phases. This study, which is essentially the CRC Flexibility* method, shows a remarkable increase in flexibility, agility and most amazingly an increase in power of up to almost 17%. That is unheard of anywhere in the research literature for a flexibility system to be able to provide that much difference. Rather than go into detail here, I will present a link to the peer-reviewed and published case study from the European, Journal of Physical Education and Sport. It references a lot of papers that are here on this page so rather than go into detail now, ill let the paper speak for itself. One note is although the title references CRAC stretching, I realised too late that what I was doing was CRC Flexibility*, which I was at least able to include in the descriptions.
Results in brief for CRC Flexibility* Methods;
- 47% average improvement in Flexibility for the sit and reach exercise,
- An average of 4% reduction in Agility run time, 6% maximum
- 10% average improvement in Power in the no-arm swing long jump exercise
- Up to 16.85% improvement in Power
https://efsupit.ro/images/stories/februarie2022/Art%2036.pdf
I would very much like to be involved in any future studies outside of the research we continue to do. Apart from support, my main contribution would be ensuring that the CRC Flexibility* techniques are performed correctly to ensure consistency throughout the research and that the best possible results can be obtained. This enables me to participate but also keep an arm’s length from the study.
Further Research
Following are Nine studies showing the incredible effects of traditional CRAC stretching and one negative as it is the closest method to CRC Flexibility*. I’ve included my thoughts on each study and also recommend much more needs to be done in this area of research.
It consistently shows how superior CRAC stretching is in increasing flexibility, balance, performance and reduction in pain. I believe these studies only scratch the surface of the potential of CRAC and having a field-tested methodology such as the CRC Flexibility* greater gains in performance and a reduction in injury will transpire.
*CRC (Contract-Reciprocal-Contract) Flexibility is the scientific name for the UltraFLX Flexibility technique
In Summary
Research into CRAC Stretching Methods have;
- Up to 37% Increase In Flexibility
- Improved Muscle Performance – ideal as a warm-up prior to training
- Significant Increase in Posture Stability
- The Stretch Reflex is more Relaxed – meaning less potential for injury
- Greatly Improved Balance
- CRAC has proved Superior to all other forms of Stretching
- Improved Flexibility and reduced back pain.
Some links will take you to a redirect page first then you will get to the study. If that doesn’t work highlight the link and copy and paste it into your search bar, it should work from there. If you find any link not working please email me at rod@theflexibilitywhisperer.com.au
1.The effect of the contract-relax-agonist-contract (CRAC) stretch of hamstrings on range of motion, sprint and agility performance in moderately active males: A randomised control trial
T Burgess; T Vadachalam; K Buchholtz; J Jelsma
The South African study found a 37% increase in hamstring flexibility using CRAC. The method of CRAC stretching was to maximally contract the muscles for 6 seconds. What is remarkable and unfortunate with this study is they found there was no increase in power or agility. This is really unfortunate because when you look at the study itself you find they only tested one muscle group, the hamstrings. However, as there are many muscle groups involved in both activities to measure speed and agility I’m surprised they made these conclusions.
2. The Effects of the Contract-Relax-Antagonist-Contract Form of Proprioceptive Neuromuscular Facilitation Stretching on Postural Stability
Ryan, Edwin E1; Rossi, Mark D1; Lopez, Richard2
A study in Florida found CRAC stretching significantly increased postural stability. This is consistent with the improvement of strength for the muscles, particularly at full range of motion. The muscle itself gets stronger and is able to limit the effects of the stretch reflex causing a slowing of movement which in turn improves reaction times throughout the body.
https://journals.lww.com/nsca-jscr/Fulltext/2010/07000/The_Effects_of_the.26.aspx
3. Differential responses to proprioceptive neuromuscular facilitation (PNF) stretch techniques.
Osternig LR, Robertson RN, Troxel RK, Hansen P.
Another study found CRAC Stretching, over and above static stretching and the traditional PNF stretching, caused an increase of 9-13% of hamstring Range of motion and an 89-110% increase in muscle EMG activity of just contracting the muscle then relaxing.
Ostering, LR, Robertson, RN, Troxel, RK, and Hansen, P. Differential responses to proprioceptive neuromuscular facilitation (PNF) stretch techniques. Med Sci Sports Exerc 22: 106-111, 1990.
4. Effects of contract-relax stretching training on muscle performance in athletes
M. Handel T. Horstmann H.-H. Dickhuth R. W. Gülch
Two studies found the mechanisms that trigger the stretch reflex, basically when the body takes over the control of movement and starts to fire the muscles because of perceived overstretching often causing some muscle damage, are more relaxed when just the CR version of CRAC stretching allowing the stretch to go much further.
5. The Effects of the Contract-Relax-Antagonist-Contract Form of Proprioceptive Neuromuscular Facilitation Stretching on Postural Stability
Ryan, Edwin E; Rossi, Mark D; Lopez, Richard
CRAC was found to greatly improve balance by increasing the connection of the neuromuscular system. Mediolateral balance is particularly important not only to improve athletic performance but to maintain it as we grow older as it is known to deteriorate with age.
[https://journals.lww.com/nsca-jscr/Fulltext/2010/07000/The_Effects_of_the.26.aspx]
6. Proprioceptive Neuromuscular Facilitation (PNF): Its Mechanisms and Effects on Range of Motion and Muscular Function
Kayla Hindle; Tyler Whitcomb; Wyatt Briggs; Junggi Hong;
Kayla et al; identified four mechanisms Autogenic inhibition, reciprocal inhibition, stress relaxation and the gate control theory which were responsible for increases in range of motion and performance using PNF CRAC method. They found both occurred when done under the correct conditions.
This is very consistent with my client’s improvements in the sporting and daily activities.
[https://content.sciendo.com/view/journals/hukin/31/1/article-p105.xml?lang=en]
7. The Effect of Proprioceptive Neuromuscular Facilitation on Learning Fine Motor Skills
Kaseb, Reza, Mehranian, Rezaei
Kaseb et al stated, it seems that proprioceptive neuromuscular facilitation, as a preparation method before performance, can enhance the efficacy of training to better learn the coordination pattern of fine motor skills.
As many studies have shown that the muscles when contracted at full stretch show increased muscle excitability thus improved neural connections this conclusion makes perfect sense. CRAC is ideal as a preparation prior to training/learning skills.
8. Gains in range of ankle dorsiflexion using three popular stretching techniques.
This study inquired whether CRAC or CR methods of stretching were superior over static stretching with regards to a muscle spaning a single joint, ie the soleus (Calf) muscle. It found CRAC stretching was superior than both other forms of stretching.
https://europepmc.org/article/med/3740242
9. Immediate effect of contract-relax antagonist-contract method on iliopsoas muscle and hamstring muscle stretching in chronic non-specific low back pain
A study conducted to find out the immediate effects of CRAC stretching on the iliopsoas muscle and hamstring muscle in chronic non-specific low back pain. The conclusions are remarkable. Not only was there significant improvement in flexibility but a noticeable reduction in back pain.
This is consistent with my experience. I had one athlete that would get knots in his back whilst surfing. After a few sessions they completely disappeared. Another said he felt lighter and was able to move far more easily pain free.
What is also noticeable about this study is they only used 25% of their perceived strength, which is what I agree with for training and warmup, unlike other studies you’ll see, using max effort will diminish performance afterwards. This I don’t agree with as a preparation.
Where PNF has been shown to limit performance
1.Maximal Strength, Number of Repetitions, and Total Volume Are Differently Affected by Static-, Ballistic-, and Proprioceptive Neuromuscular Facilitation Stretching
Barroso, Renato; Tricoli, Valmor1; Santos Gil, Saulo dos; Ugrinowitsch, Carlos; Roschel, Hamilton
This study was conducted to test ballistic stretching, static stretching and PNF CR (ie just the first phase of CRAC only) Their results show PNF and static stretching hampered performance but during the contraction the PNF stretch was at near maximal contraction.
This is common among most research studies where PNF CRAC or CR was hampering performance and I believe maximum muscle contraction has shown to fatigue the fast twitch fibres and explains the loss of explosive performance. As the previous article shows, sub max (ie 20- 25% of Max) does show far better results.
I believe it is very important to continue this research but not to use Maximal contractions for PNF CRAC protocols.