Muscle News Weekly June 23 2014, 0 Comments
Strength training: Which is better? Movement velocity of your movements or the time under tension?
Everyone wants the edge in their training program. We all know that changing up your training from time to time is important to limit adaptations to the exercise. That's why i find this new study fascinating. It looked at whether the velocity of exercise made any difference to strength adaptations. In the International Journal of Sports Medicine, they looked at the squat exercise with maximal intended velocity and half maximal velocity.
They found that movement velocity was of greater importance than time under tension for inducing strength adaptations. If you aren't adding maximal velocity training into your program, you should. However, its best to continue adding other variables such as repetition changes, weight changes, etc to keep the body on its toes.
The Multifidus muscle in low back pain. 2 new studies that add to the confusion
The multifidus muscle has long been implicated in low back pain. So what do we do? We do core training and stabilization and a host of other exercises to strengthen that muscle. We do know that if you don't exercise after getting an episode of low back pain, there may be wasting of that muscle. Sometimes there's fatty infiltration into the muscle, which we conclude is bad. Well, a new study in the journal Spine did a 9 year study follow on whether this fatty infiltration can predict future low back pain. The answer is no. There is no correlation with future low back pain and intramuscular fatty infiltration. So if there is no correlation, then why the huge trend towards stabilization exercises? What's your experience with this?
And on that note, another study in the journal Physical Therapy in Sports assessed whether a labile surface like a gym ball was more effective at stimulating the multifidus muscle than stable surfaces. As anyone who has ever added gym ball exercises to their repertoire, the research found that labile surfaces were more effective and helped increase the size of the multifidus muscle with increasing instability of the surface.
Two things to take away from this: We really don't know whether the fatty infiltration of the multifidus will lead to low back pain. That begs the question 'exactly what can we do then to do the multifidus to see improvements in low back recurrence'. However, if you are seeing someone with chronic low back pain. continue using a swiss gym ball to keep working the multifidus.
Does increased activity lead to degenerative changes later in life?
I referenced a study earlier on that looked at the effects of high endurance running on the knees of an older man. It turns out that the pounding of activity didn't lead to any significant degenerative changes. Mind you, this one person didn't have any significant injuries through his years of training. After I referenced that article, i had a heated debate with a physician friend of mine that said that wear and tear on the body will always lead to changes. Well, here's another study that lays doubt to the people that use this as an excuse not to exercise!
A new study in the journal Biomedic Research International (get full free article by clicking here) looked at two groups of men over a 25 year period. One group enrolled in the military and served at least 3 years as elite infantry soldiers, while the other group were deferred from army service for full time religious studies. Turns out that 25 years later, in the elite infantry group, only the lumber spine but not the knees showed any degenerative changes on MRI.
I'm starting to see these nuggets of information coming out more and more and makes me re evaluate whether physical activity is 'bad' for you as some may say. There's just too much research and support for being active throughout your lifetime. Don't start believing that degenerative changes are going to accelerate because you're going to be more active than usual.
Does muscle activation deficits limit strength gains for those with TKA (Total Knee Arthroplasty)?
If you're one of those that assess muscle movement patterns in your clients or patients (I'm in this group), then you probably know the importance of normalizing movement patterns prior to initiating any strengthening program. For years, I've always looked at quadriceps muscle activation prior to initiating a strengthening program for those with TKA. A new study tells me to not bother (I'm going to do it anyways. What does ONE study know, right? )
The study was found in the International Journal of Sports Physical Therapy. They found that initial functional limitations in quadriceps activation did not predict quadriceps strength following a strength training intervention.
That doesn't mean you should forget about abnormal movement patterns. One of the conclusions presented was that you shouldn't delay strength training in favor of normalizing muscle activation. In my experience, its more art than science. Some patients respond well to improving muscle activation patterns, while others don't. Strengthening usually doesn't get delayed because of this. Muscle activation training is added in addition to the strength training program. Whats your take on this? Do you have similar experiences or differ completely? Let us know.
How long should you hold a static stretch to see any benefits in speed and agility?
I'm not a big proponent of static stretching, although I know some trainers still use it. Here's an interesting study that may shed some light on it, or create more confusion altogether.
The goal of the study, published in the Journal of Strength and Conditioning Research, was to see if various static stretching times increased speed and agility in athletes. After an 8 minute cardio warm up, they performed static stretching for various periods of time.
Turns out, a short static stretch of about 15 to 20 seconds produced greater improvements in speed, but no improvements in agility. All other static stretch times were neither beneficial nor detrimental. The study also found that this applied more to those with less agility and speed performance levels. Moral of the story? Do short static stretching only for your average athlete. Not exactly mind blowing but saves us from seeing someone hold a static stretch for a few minutes.
Another examination test for rotator cuff tears bites the dust....
In the last Muscle News Weekly article (click here), we looked at some tests that seemed to be of some value in diagnosing rotator cuff tears. Today, we look at the other end and see a couple of tests that don't seem to live up to the promise. (Of course, one has to base this decision on their experience - so don't shoot the messenger).
A study in the American Journal of Sports Medicine looked at 139 participants at 2 tertiary orthopaedic clinics. They found that the internal rotation and external rotation lag sign tests did not improve the ability to diagnose subscapularis and supraspinatus tears, respectively. However, in their own words, 'no test in isolation is sufficient to diagnose a patient with rotator cuff damage'. The moral of the story is to never use one test by itself. However, this study will make me reevaluate my initial jerk reaction when i use the lag sign tests. Check out the following videos that gives you a demonstration of the 2 tests.
Internal Rotation Lag Sign
External Rotation Lag Sign
Movement velocity vs. Time under Tension. Which produces greater athletic performance?
The International Journal of Sports Medicine just published a cool new study that assessed whether the training velocity had any impact on strength training adaptations. They assessed squat training at full velocity and half velocity. It appears that movement velocity was more important than time under tension to induce adaptations for increasing sports performance. Another thing to note is that both half velocity and full velocity got the greatest increase in squat performance at their training velocities.
This study may not provide any new information that most may already know. Best strategy would be to always ensure you are recording the data of all the training parameters and adjusting accordingly based on the athlete's response to the training.