Isometrics for patellar tendonitis?

We are familiar with different modes of exercise: isometric, isotonic and isokinetic. Isometric exercises have a physiological overflow of 10 degrees on each side of the point of application (ie; to do the exercise at 20 degrees flexion, and you have strength gains from 10 to 30 degrees); isotonics and isokinetics, 15 degrees. Taking advantage of physiological overflow often allows us to bypass painful ranges of motion and still strengthen in that range of motion. 

In this study, they looked at immediate and 45 minute later pain reduction (not function) comparing isometric (max voluntary quadricep contraction) and isotonic (single leg decline squat) exercises. They also looked at cortical inhibition (via the cortico spinal tract) as a result of the exercises. 

Here is what they found: “A single resistance training bout of isometric contractions reduced tendon pain immediately for at least 45 min postintervention and increased MVIC. The reduction in pain was paralleled by a reduction in cortical inhibition, providing insight into potential mechanisms. Isometric contractions can be completed without pain for people with PT. The clinical implications are that isometric muscle contractions may be used to reduce pain in people with PT without a reduction in muscle strength.” These same results were not seen with the isotonic exercise. 

Did the decrease in pain result in the decrease in cortical inhibition (muscle contraction is inhibited across an inflamed joint: Rice, McNair 2010; Iles, Stokes 1987)? Was it a play on post isometric inhibition (most likely not, since this usually only lasts seconds to minutes post contraction) ? Or is there another mechanism at play here? There has been one other paper we found here, that shows cortical inhibition of quadriceps post isometric exercise. Time will tell. In the meantime, start using those multiple angle isometrics!

The Gait Guys

Rio E, Kidgell D, Purdam C, Gaida J, Moseley GL, Pearce AJ, Cook J.Isometric exercise induces analgesia and reduces inhibition in patellar tendinopathy Br J Sports Med. 2015 May 15. pii: bjsports-2014-094386. doi: 10.1136/bjsports-2014-094386. [Epub ahead of print]

http://www.anatomy-physiotherapy.com/28-systems/musculoskeletal/lower-extremity/knee/1163-isometric-exercises-in-patellar-tendinopathy

More effective stretching, Part 2

Last week we looked at one (of many) methods to make stretching more effective, utilizing a neurological reflex called “reciprocal inhibition” If you missed that one, or need a review, click here. 

Another way to get muscles to the end range of motion is to utilize a technique called “post isometric relaxation”. Notice I did not say to lengthen the muscle; to actually add sarcomeres to a muscle you would need to use a different technique. Click here to read that post.

Contracting a muscle before stretching is believed to take advantage of a post isomteric inhibition (sometimes called autogenic inhibition), where the muscle is temporarily inhibited from contracting for a period immediately following a isometric contraction. This has been popularized by the PNF stretching techniques, such as “contract hold” or “contract relax” . EMG studies do  jot seem to support this and actually show muscle activation remains the same (1, 2) or increased after contraction (3-6). Perhaps it is due to an increased stretch tolerance (7,8). 

The technique was 1st described by Mitchell, Morgan and Pruzzo in 1979 (9). These gents felt it was important to utilize a maximal contraction (using 75-100% of contractile force) to get to have the effect. It was later shown by Feland and Marin (10) that a more minimal, submaximal contraction of 20-60% accomplished the same thing.  Lewit felt that a less forceful contraction offers the same results, and combined respiratory assists (inspiration facilitates contraction, expiration facilitates relaxation) with this technique (11). Interestingly, there are bilateral increases in range of motion with this type of stretching, indicating a cross over effect (12). Regardless of the mechanism, the phenomenon happens and we can take advantage of it. 

This is how you do it: 

• Bring the muscle to its end range (maximum length) without stretching, taking up the slack. This should be painless, as this will elicit a different neurological reflex that may actually increase muscle tone. 
• resist with a minimal isometric contraction (20-60%) and hold for 10 seconds.  You can inspire to enhance the effect.
• relax and exhale slowly. It is important to wait and feel the relaxation. Stretch through the entire period of the relaxation. You should feel a lengthening of the  muscle.
• repeat this 3-5 times

This technique can also be used with the force of gravity offering isometric resistance. In a hamstring stretch, you could lean forward while maintaining the lumbar lordosis and allowing the weight of the upper body to provide the stretch. 

Wasn’t that easy? Now you have another tool in your toolbox for yourself or your clients.

The Gait Guys. Giving you useful information and explanations in each and every post.

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2. Cornelius WL. Stretch evoked EMG activity by isometric coontraction and submaximal concentric contraction. Athletic Training. 1983;18:106–109
3. Condon SM, Hutton RS. Soleus muscle electromyographic activity and ankle dorsiflexion range of motion during four stretching procedures. Phys Ther. Jan 1987;67(1):24–30 
4. Mitchell UH, Myrer JW, Hopkins JT, Hunter I, Feland JB, Hilton SC. Neurophysiological reflex mechanisms’ lack of contribution to the success of PNF stretches. J Sport Rehabil. 2009;18:343–357 
5. Youdas JW, Haeflinger KM, Kreun MK, Holloway AM, Kramer CM, Hollman JH. The efficacy of two modified proprioceptive neuromuscular facilitation stretching techniques in subjects with reduced hamstring muscle length. Physiother Theory Pract. May 2010;26(4):240–250 
6. Osternig LR, Robertson R, Troxel R, Hansen P. Muscle activation during proprioceptive neuromuscular facilitation (PNF) stretching techniques. American journal of physical medicine. Oct 1987;66(5):298–307
7. Mahieu NN, Cools A, De Wilde B, Boon M, Witvrouw E. Effect of proprioceptive neuromuscular facilitation stretching on the plantar flexor muscle-tendon tissue properties. Scandinavian journal of medicine & science in sports. Aug 2009;19(4):553–560 
8. Mitchell UH, Myrer JW, Hopkins JT, Hunter I, Feland JB, Hilton SC. Acute stretch perception alteration contributes to the success of the PNF “contract-relax” stretch. J Sport Rehabil. May 2007;16(2):85–92
9. Mitchell F Jr., Moran PS, Pruzzo NA: An Evaluation of Osteopathic Muscle Energy Procedures. Pruzzo, Valley Park, 1979.  
10. Feland JB, Marin HN. Effect of submaximal contraction intensity in contract-relax proprioceptive neuromuscular facilitation stretching. Br J Sports Med. Aug 2004;38(4):E18.
11. Lewit K: Postisometric relaxation in combination with other methods of muscular facilitation and inhibition. Man Med, 1986, 2:101-104.
12. Markos PD. Ipsilateral and contralateral effects of proprioceptive neuromuscular facilitation techniques on hip motion and electromyographic activity. Phys Ther. Nov 1979;59(11):1366–1373