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Monthly Archives: July 2011

Wilson et al, in the most recent issue of Clinical Biomechanics, looked at differences in gluteus maximus and gluteus medius functioning in females with patellofemoral pain syndrome (PFPS). The authors, in their introduction, point out that PFPS is experienced disproportionately by females and that those females have altered hip joint kinematics during running.

The authors studied two groups of recreational female runners, aged 18-35. One group suffered form PFPS, one did not. For both groups, gluteus medius and maximus activity was analyzed during a maximum voluntary isometric contraction (MVIC), hip motion, and during 20 meters of running.

The authors found some differences between the runners with PFPS and those without:
• During running, the gluteus medius was activated 24ms earlier before foot contact in individuals without PFPS. It also remained active 42 ms longer in individuals without PFPS.
• This difference resulted in greater hip adduction excursion and greater hip internal rotation excursion during running for individuals with PFPS.
• No differences between the groups in terms of gluteus maximus activation.

This is interesting from the standpoint that female runners with PFPS have some altered gluteus medius activity, which impacts running kinematics. It is unclear if the gluteus medius activity causes the PFPS or is caused by it and the study cannot answer this question. It’s also unclear what long-term negative effects might be caused by this alteration in hip kinematics. Finally, it needs to be kept in perspective that the study was very limited in terms of its subject pool so it is unclear how much of its results can be applied to individuals outside that subject pool.

Wilson, J.D., Kernozek, T.W., Arndt, R.L., Reznichek, D.A., and Straker, J.S. (2011). Gluteal muscle activation during running in females with and without patellofemoral pain syndrome. Clinical Biomechanics, 26: 735-740.

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In an August 2011 issue of Medicine and Science in Sports and Exercise, Takskanen et al studied markers of overreaching with military recruits. The idea was to determine if oxidative stress markers and antioxidants could distinguish between individuals that suffered overreaching and those that did not.

Subjects were monitored during 8 weeks of basic training, their aerobic fitness was evaluated during weeks 1, 5, and 8. Blood work, submaximal exercise testing (20kg backpack march), psychological questionnaires, and body composition were also all evaluated.

Over the 8 weeks of the study, there were several results:
• First, like you’d expect basic training improved maximal oxygen consumption. The interesting thing is that the improvements leveled off after the first five weeks.
• 31% of the subjects met the study’s criteria for overreaching. In these subjects: Oxidative stress markers were higher at rest and at baseline for these subjects.
• These subjects had a different response to exercise in terms of oxidative stress markers than subjects not experiencing overreaching.

What is unclear from this study is if there is some kind of predisposition to overreaching on some of the subjects or if variation in sleep, activity level, and nutrition lead to the overreaching or if there is a combination of factors at work. The authors do not report on if there are fitness or body mass differences between those suffering overreaching and those who do not, which could also be factors that effect this.

Nevertheless, this is one of the first studies to establish that overreaching might be associated with oxidative stress markers.

Tanskanen, M.M., Uusitalo, A.L., Kinnunen, H., Hakkinen, K., Kyrolainen, H., and Atalay, M. (2011). Association of military training with oxidative stress and overreaching. Medicine and Science in Sports and Exercise, 43(8), 1552-1560.

Requena et al had a study published in the August Journal of Strength and Conditioning Research looking at the relationship between back squat strength, ballistic squat performance, vertical jump, and sprint speed.

The authors studied 21 “semiprofessiona;” sprinters (100 and 200 meter sprinters), though we are not given information about their performance on the 100 meter or 200 meter races.

It needs to be pointed out that the squat tests were unusual. Both traditional and ballistic squats were evaluated on a Smith machine. They were also tested having the subjects squat down to 100 degrees of knee flexion, hold it for two seconds, then perform the concentric phase of the lift.

Subjects were also tested on their vertical jump and 80 meters of sprints (with 10 meter splits recorded). These results were then correlated with the 1-RM on the traditional squat as well as maximal peak and average power on both squat tests.

The results are interesting:
• The vertical jump correlated with power values of the ballistic squat but not the 1-RM traditional back squat.
• Power outputs from the ballistic squat were more highly correlated with vertical jump performance than the traditional squat.
• The sprint times correlated with the 1-RM on the traditional squat as well as the power values for both kinds of squats.
• There was a trend for the ballistic squat power outputs to be more strongly correlated with sprint times than traditional squats.

The study is interesting from several standpoints. First, it is using a homogenous group of sprinters. This is both an advantage and a concern. An advantage because the results are very relevant to this population, a concern because the application of the results may be restricted to this population. Second, the relationship (or lack thereof) between vertical jump performance and 1-RM is counter-intuitive. This is something that warrants further study. Third, the trend for ballistic squat performance and vertical jump/sprint performance is interesting and warrants further study. Is this something that would apply more to one group of athletes or one level of ability rather than others?

Requena, B., Garcia, I., Requena, F., de Villarreal, E.S-S., and Cronin, J.B. (2011). Relationship between traditional and ballistic squat exercise with vertical jumping and maximal sprinting. Journal of Strength and Conditioning Research, 25(8), 2193-2204.

Cluster training, which essentially means putting little rest periods into a set, have become increasingly popular over the last several years. Despite this, there has been little research to support the theory. In the August issue of the Journal of Strength and Conditioning Research, Hansen et al looked at this using elite rugby union athletes.

The authors used 18 elite rugby players and divided them into one of two training groups, one a traditional training group and the other a cluster training group. All subjects were evaluated via 2-6 RM back squat (athletes failed at a 2-6 RM load and then 1-RM was predicted based upon this load). Jump squat performance was evaluated at bodyweight, 20kg, 40kg, and 60kg.

The athletes trained twice a week for eight weeks. Each week the loads varied from 80-95% and the exercises changed from week to week. Each training session saw a complex of squat variations and clean variations. Both training groups performed the same exercises, the same loads, and used the same volume. The difference is that the cluster group broke up sets into 2-3 mini-sets with 10-30 seconds rest between clusters.

At the end of eight weeks,:
• The traditional group improved their 1-RM by 18%, the cluster group by 13%.
• The traditional group improved peak power by an amount ranging between 0.5% and 5% depending upon the jump squat load. The cluster group improved by between 3% and 7%.
• The traditional group improved peak velocity by an amount ranging between 0% and 2% depending upon the jump squat load. The cluster group improved by between 2% and 4%.
• The traditional group improved peak force by an amount ranging from -.2% to 2% depending on the jump squat load. The cluster group improved by between .2% and 2%.

As it was performed in this study, cluster training seemed to be effective at increasing strength, power, force, and velocity. It does not appear to have been more effective than traditional training. Now, these results, while extremely interesting, need to be viewed with caution. First, the results may only apply to this population. Second, it’s always possible that a different cluster training program might have yielded different results (for example, longer/shorter rest periods on the clusters). Third, the exercises and loads selected might not have been optimal for increasing strength and power (though I don’t agree with that).

Hansen, K.T., Cronin, J.B., Pickering, S.L., and Newton, M.J. (2011). Does cluster loading enhance lower body power development in preseason preparation of elite rugby union players? Journal of Strength and Conditioning Research, 25(8), 2118-2126.

Fragala et al in the August 2011 issue of Sports Medicine had an excellent literature review looking at endocrine and immune responses to exercise and how these are different based upon gender.

First, the authors note that men and women experience exercise differently in terms of endocrine function:
• Women tend to fatigue more quickly but recover faster than men.
• The inflammatory response from exercise is more pronounced for women than men.
• Testosterone increases in response to strength training (in men) but not in women.
• Women use more fat for fuel (and less carbohydrates) during endurance exercise than men.

Second, they point out differences between males and females with regards to the immune system:
• Women have a superior ability to form antibodies after infection
• Women experience lower rates of disease
• Men are more prone to infectious disease whereas women are more prone to autoimmune disease.

These immune differences may carry over to exercise, with the authors noting that:
• Women have a more pronounced immune response to endurance exercise than men
• Women have a greater inflammatory response following strength training than men

The ultimate cause of these differences seems to be the sex hormones. According to the authors, estrogen promotes immune function and drives the different responses to exercise that women experience. Testosterone may have a negative effect on immune function.

The immune (inflammatory) response has been linked to delayed onset muscle soreness. With these gender differences in mind, it would be interesting to determine if women experience delayed onset muscle soreness differently than men.

The other interesting thing to note about hormonal studies and exercise; there’s a lot of great information about the acute effects of exercise on hormones. In other words, this session increases testosterone, growth hormone, etc. There is also a lot of research showing what types of training loads/volumes are best for increasing circulating hormonal levels acutely. But there is little showing long-term hormonal elevations from exercise. This suggests that the acute response is what drives adaptation, which also implies a need to apply the overload principle as this acute response becomes blunted over time. The authors did a great job of addressing the acute effects of exercise on circulating hormones, but were silent about chronic effects in this article.

Fragala, M.S., Kraemer, W.J., Denegar, C.R., Maresh, C.M., Mastro, A.M., and Volek, J.S. (2011). Neuroendocrine-immune interactions and responses to exercise. Sports Medicine, 41(8), 621-639.

Argus et al had a study published in the August Journal of Strength and Conditioning Research looking at the impact of assisted, resisted, and bodyweight vertical jump training on vertical jump height.

The study involved two parts. In the first part, recreational weight trainers performed jumps on a force plate under resisted, assisted, and bodyweight conditions. Resisted involved performing jumps with elastic bands attached from the subject’s waist to the floor (i.e. resistance on the concentric phase of the jump). Assisted involved elastic bands attached from the subject’s waist to the ceiling (helps the subject during the concentric part of the jump). Bodyweight was a normal jump without any kind of assistance or resistance.

This part of the study found that the assisted jumps had the greatest peak vertical velocity and peak power, followed by free jumps, followed by resisted jumps. Peak force was greatest for resisted, followed by bodyweight, followed by assisted jumps.

The second part of the study involved four weeks of contrast training with rugby players. Twice a week they performed a set of four power cleans followed by six jumps under one of the three conditions. At the end of four weeks, the assisted group increased their jump height by almost 7%; the resisted group by almost 5%, the bodyweight group by almost 1.5%.

This is an interesting study because there are diminishing returns with exercise. As we become stronger it becomes more difficult to increase strength. As we become a more advanced athlete, it becomes more difficult to increase power. This study suggests some simple ways to make plyometrics more effective as athletes advance in fitness.

Argus, C.K., Gill, N.D., Keough, J.W.L., Blazevich, A.J., and Hopkins, W.G. (2011). Kinetic and training comparisons between assisted, resisted, and free countermovement jumps. Journal of Strength and Conditioning Research, 25(8), 2219-2227.

We completed our next little league conditioning session last night. I’m slowly starting to shift gears with them and beginning to apply some of the skills they’ve been learning to baseball.

Up until now we’ve been doing falling starts for the sprints, this is to reinforce the knee drive and arm action during the start so that the athletes learn to take the first step explosively. Beginning yesterday we’ve dropped the falling starts in favor of a standing start. This was followed by a number of 10-yard sprints (it’s baseball). The last few were timed to give the kids some motivation and brag material. A MLB player can run 10 yards in around 1.5 seconds, our kids were averaging 2.2 seconds.

Up until this point, agility has been teaching footwork and to keep the center of gravity low. Today the pro agility drill was incorporated. This is a great deal that reinforces staying low, explosive starts, sudden stops, and changing direction. It’s also very applicable to base running. No timing for these drills, the focus was on getting the kids comfortable with how to move.

After the speed and agility work, it’s time for plyometrics and general conditioning. Today the plyometrics involved jumping over mini-hurdles. Basically the hurdles are laid out so that the kids have to work on horizontal jumping (i.e. they are far apart) but the six inch tall mini-hurdle adds a vertical component to the exercise.

After that I broke out the medicine balls, which is a lot of fun for kids. I had them pair up based upon size and then had them do the backward overhead medicine ball toss to each other. The concept of using the legs to throw (or using the legs to bar for that matter) is really hard for them, and this exercise helps to tie it together but it will be a long time before they are good at it (nobody threw the ball 10 yards yesterday).

I’m constantly trying to find fun ways to strengthen the ankle, shins, and feet to help prevent some of the issues that athletes develop when the engage in speed and agility work. Today the kids performed chest passes with the medicine balls. Once they were comfortable with that, I had them do the chest passes standing on one leg – this is a great workout for the foot, ankle, and shin.

Everything ended up with wheelbarrows (one athlete “walks” on his hands while the other athlete holds the walkers ankles). This requires them to develop some upper body strength, they need to keep their midsection tight (straight line from the shoulders to the ankles), and it is a lot more fun than push-ups.

After the conditioning work, the kids spent about 30 minutes working on baserunning drills that really applied everything they’ve been doing in conditioning.  For example, if they are on first base and there is a pop fly, what do they do?  When do they run to second, when do they run back to first?

I survived another NSCA National Conference in Las Vegas. As usual, it was great to reconnect with friends and meet new ones. I gave my presentation: “Evidence Based Core Training: A Contradiction in Terms” on Thursday. I took the approach that the NSCA is supposed to be here to bridge the gap between research and application and this is one area where there is a serious gap in our research knowledge.

The presentation that I gave started with the definition of “What is the core?” Essentially there is no consensus on this. Some authors list everything between the shoulder and the knees, some just focus on the belt around the abdomen. Next I covered what we think: core training improves performance, prevents lower back injuries, and treats lower back injuries. This was followed with covering the research that forms the foundation behind those beliefs, while doing that I also explained how in many cases we have stretched what the research says to fit what we want it to say (i.e. the foundational research is extremely limited in its application and scope). Finally I covered the research that exists on performance improvement, injury prevention, and injury treatment. As I’ve written about elsewhere, the research either doesn’t support or it is heavily conflicting and there is no consensus about the value of core training in terms of injury prevention, injury treatment, and performance improvement. Much of the research that I reviewed was from Spine, European Spine Journal, British Medical Journal, JAMA, Journal of Strength and Conditioning Research, Medicine and Science in Sports and Exercise, Experimental Brain Research, and Best Practice and Research Clinical Rheumatology. I concluded with some general thoughts on where the research needs to go if we want to base core training on more than myth, marketing, and wishful thinking.

After the presentation, I met Carmen Bott (from http://www.humanmotion.com ). She gave me a great pdf called “The Myth of Core Stability” by Professor Eyal Lederman. In it, a number of interesting points are made concerning core stability and lower back pain:
• There is little relationship between core stability and lower back pain during pregnancy, which is a time during which the abdominal muscles are undergoing elongation, lose the ability to produce force, and lose the ability to stabilize the pelvis. The same argument (according to Dr. Lederman) can be made during inguinal hernia, surgery, and obesity.
• Core training ignores how we learn motor skills. In other words, we learn motor skills in the manner in which we practice this, but this does not necessarily transfer to other aspects.
• Hollowing/tightening the abdominal muscles may actually increase the strain on the lumbar spine.
• Most injuries happen too quickly for the nervous system to respond with a protective motor pattern.

It was a very thoughtful article and I appreciate Carmen’s sending that my way.