Skip navigation

Monthly Archives: May 2011

Strength training can cause skeletal muscle to hypertrophy, or grow larger. Clearly this is a reason that many people engage in this type of exercise. Larger skeletal muscle also has the potential to be stronger and more explosive, which makes it very attractive when it comes to conditioning athletes.

Skeletal muscle has lots of different properties that can influence its ability to perform. For example, it can be made up of more fast-twitch or more slow-twitch muscle fibers, resulting in an athlete who is potentially stronger and faster versus one geared more towards endurance. It can have greater (or lesser) concentrations of enzymes, mitochondria, glycogen, and other substrates which potentially has an impact on performance.

In addition to that, there are two interesting architectural qualities which seem to heavily influence performance. The first relates to how that hypertrophy is distributed along the muscle. Research on sprinters and football players has shown that those athletes with more muscle mass in their upper thighs were faster than those with less. This is interesting because it’s unclear if it is trainable, but it suggests that the muscles don’t respond to hypertrophy training in a uniform manner throughout the muscle. The second relates to how the muscle fibers are oriented related to the tendon. Those muscle fibers that are at a greater angle relative to the tendon are called pennate muscle fibers and are capable of generating more force. Those muscle fibers oriented more straight up and down can’t generate as much force, but they shorten faster. Strength training can increase the pennation angle of the muscle fibers, but it suggests that there may be a trade-off depending upon the qualities one wants to emphasize.

In the June issue of the Journal of Strength and Conditioning Research, Matta et al. looked at how hypertrophy training effects the muscle thickness of different sites of the biceps and triceps as well as how it effects the pennation angle of the triceps at different sites.

They had 40 subjects perform twelve weeks of resistance training, three times per week, working out the upper body on a nonlinear periodization program (one day light, one day medium, one day heavy per week). At the end of twelve weeks strength increased significantly and the subjects experienced hypertrophy of the biceps and triceps. What is interesting is how they experienced it, basically the biceps and triceps reacted differently.

Muscle thickness was taken at three sites at the biceps and triceps; proximally (near the shoulder), mid, and distally (near the elbow). The biceps increased muscle thickness by almost 12% at the proximal location, almost 7.5% at the mid location, and almost 5% at the distal location. By comparison, the triceps increased muscle thickness by 2-3% at the proximal and distal locations and by almost 5% at the mid location. For the triceps, the mid location was the only part of the muscle that experienced a statistically significant increase in muscle thickness.

The triceps was the only muscle studied in terms of changes in pennation angle. The changes in pennation angle ranged from approximately a 16% increase at the distal site to an almost 20% increase at the proximal site (though there are no statistically significant differences between how the sites responded).

The fact that the biceps and triceps respond differently to training is fascinating. With 40 subjects in the study, it is unlikely this is due to a particular individual’s genetic variability, it probably reflects the fact that both muscles really do respond differently. Now, the inclusion of different exercises or following the subjects over a longer course of time might have caused different results. It’s also not clear that this applies outside of those muscle groups or what role genetics is going to play.

It would have been interesting to compare the changes in pennation angle at the triceps with changes to the biceps to see if both muscles respond in a similar manner at all sites.

Matta, T., et al. (2011). Strength training’s chronic effects on muscle architecture parameters of different arm sites. Journal of Strength and Conditioning Research, 26(5): 1711-1717.

Advertisements

Paulson and Braun conducted a study looking at the impact of sprinting with a parachute on Division II track athletes. Using a parachute to sprint falls into the category of resisted sprinting, which is designed to make the sprinting motion more difficult. The idea is that by making the motion more difficult, the body will recruit more muscle fibers to overcome the resistance and this will eventually carry over to non-resisted sprinting, resulting in a faster athlete. There are a number of resisted sprinting tools; weighted sleds, dragging tires, wearing a weighted vest, sprinting with a teammate attached to you, running uphill, etc.

The first big concern with resisted sprinting is that too much resistance has a detrimental effect on the athlete. When the resistance is too great it dramatically alters the way in which the athlete runs; the athlete’s stride length shortens, stride frequency decreases, the amount of hip extension they produce decreases (this means less force is exerted against the ground), more time is spent on the ground, etc. In short, too much resistance teaches the athlete to run slowly and with bad form – which are not qualities that we want to reinforce in our athletes.

A second concern is that many of the resisted sprinting tools may encourage poor form. For example, when towing a sled or a teammate the weight typically attaches around the athlete’s waist. This encourages the athlete to lean forward while sprinting, which decreases their ability to extend their hip when running. Sprinting with a weighted vest or sprinting uphill would alleviate this problem.

A third concern is that many studies use non track athletes. There are pro’s and con’s to this and it relates to the entire reason for using resisted sprinting in the first place. In a classic paper, Ozolin postulated the existence of a “speed barrier.” His theory was that elite sprinters train themselves to run at certain speeds and are unable to get past this point (his so-called speed barrier). He felt that resisted (and assisted) sprinting methods were necessary to train the athlete to break through the speed barrier. Now, it’s unclear if this really exists. It’s also unclear if this would exist outside of track and field athletes. One could argue that an elite sprinter, who has been training like this for almost 20 years, would have different training needs than a college football player.

When it comes to research, using non track athletes could heavily influence the results because non track athletes may or may not have good, consistent sprinting form to begin with. If they don’t have good form, then research that shows that a given tool negatively effects their form has to be interpreted with that in mind.

Paulson and Braun studied twelve Division II track and field athletes. Their athletes had two sessions, one running 2×40 yard sprints without the parachute (NC) and one running 2×40 yard sprints with the parachute (PR). All sprints were filmed.

There were differences between the two conditions:
• First, the PR sprints were slower. The 40 yard time was almost 4.5% slower than in the NC condition and the average running speed with the parachute was 3% slower than in the NC condition.
• Second, the PR had an impact on joint angles at the point of initial ground contact during the sprint – though none were statistically significant:
o Shoulder angle decreased by 13%
o Elbow angle, knee angle, and ankle angles all changed by around 1%
o Trunk angle increased by almost 23% (i.e. the athlete leaned forward more with the parachute)
o Hip angle increased by almost 6%
• The authors report no statistically significant changes in ground contact time, stride length, or stride frequency though we are never given those numbers to make our own interpretations.

Even though the changes may not be statistically significant, the study shows that the resistance of the parachute alters the running mechanics of the athletes with that increased trunk lean and changes at the hip angle. For this reason, it would have been valuable to see the stride length/frequency and ground contact data. The fact that speed decreased by around 4.5% indicates that this would be an effective tool. Clearly adding resistance to an athlete is going to slow them down, the recommendation is that athletes should not be slowed down by more than 10% or the training tool may be ineffective.

It needs to be kept in mind that this study has limitations. First, as I mentioned above there are pro’s and con’s to looking at track athletes. We can be reasonably sure that they know how to sprint, but the largest application for this training tool will be with non-track athletes. Second, the authors only analyzed one gait cycle and it’s possible that had more been analyzed the results may have been very different. Third, the study does not give the reader any information about the effectiveness of the parachute. In other words, the study tells us that it alters kinematics somewhat and that it reduces speed in the acceptable range, but we aren’t told if using the tool for a period of time will ultimately result in faster athletes.

Paulson, S. and Braun, W.A. (2011). The influence of parachute-resisted sprinting on running mechanics in collegiate track athletes. Journal of Strength and Conditioning Research, 25(6): 1680-1685.

Moir et al had a study published in the June issue of Strength and Conditioning Journal essentially looking at post activation potentiation (PAP) and female volleyball players. The idea behind PAP is that a maximal force activity (like a really heavy squat) can produce a short-term increase in power. There are a lot of theories for why this could occur, everything from cueing the nervous system to making the muscle fibers more sensitive to calcium. In practice, this might involve performing a back squat at 90% of 1-RM for 2-3 reps followed by a set of counter-movement jumps (back in the day these approaches were called complexes).

PAP is one of those things that sounds really good. The challenge is that the research is extremely mixed as to its effectiveness. It appears that this is more effective with stronger athletes than with untrained subjects. It also appears that this is very task-specific, being present on certain types of explosive activities but not on others.

Moir et al investigated eleven division II female volleyball players. The athletes performed three familiarization counter-movement jumps in a session, were tested on their 1-RM on the back squat in another session, then in subsequent sessions performed each of the following protocols (all separated by several days):
• High Load (HL): Back Squat 2×50%, 1×70%, 3×90% followed by 2 minutes rest, then 10 counter-movement jumps (1 jump every 2 minutes).
• High Volume (HV): Back Squat 12×37% followed by the same jumping protocol as in the HL condition.

Results:
• On average, the subjects’ 1-RM on the squat was 143% of bodyweight.
• The HL protocol increased their knee flexion angles during the CMJ’s by 16%, in the HV protocol the athletes increased their knee flexion angles during the CMJ’s by 22%.
• When looking at the group means, the HL protocol did not increase jump height, the HV protocol actually reduced their jump height by 4%. Now, in the text the authors note that in the HL protocol 45% of the subjects actually increased their jump height with 18% having a decline in performance.
• The HL group increased their vertical stiffness by 16%, the HV group increased their vertical stiffness by 4%.

This study has mixed results with interesting implications. First, the protocol had no effect on jump height. However, the HL protocol significantly improved vertical stiffness. It is very likely that there was no improvement in jump height because the counter-movement jump is not one that requires a great deal of stiffness from the lower extremities. Had the researchers used a drop jump instead, the HL protocol may have had a positive effect on jump height.

This brings an important point about PAP and its research. It’s very likely that PAP, if it exists, has a positive effect on very specific types of performance – namely those involving a need for leg stiffness. This would include the jumps in track and field events, landings, agility, and sprinting (though research on this is mixed at best). It probably doesn’t improve performance in tasks that don’t require that leg stiffness (for example, a jump shot in basketball which would be similar to a counter-movement jump).

There are no magic bullets in terms of exercise. In other words there is no special drill, exercise, or training protocol that will magically improve someone’s performance. So PAP and other approaches to training need to be kept in perspective.

Having said that, even if it doesn’t enhance explosiveness PAP (or complexes as I learned them) would be extremely beneficial to an athlete who is in-season. This is due to the fact that when combining the training modes (heavy strength training plus explosive training), one is able to get more work done in a shorter period of time – which is really important when practice, competition, and travel have to be taken into account.

Moir, G.L., Mergy, D., Witmer, C.A., and Davis, S.E. (2011). The acute effects of manipulating volume and load of back squats on countermovement vertical jump performance. Journal of Strength and Conditioning Research, 25(6), 1486-1491.

I attended a webinar today run by the Office of Special Education Programs (OSEP), which among other things monitors and verifies the compliance of states with the Individuals with Disabilities Education Act (IDEA). IDEA is the act that establishes that children with disabilities are guaranteed free appropriate public education in the least restrictive environment possible. It provides for early childhood intervention and for special education.

The webinar dealt with the fact that OSEP is going to be requiring states to identify something focused that they are going to improve as a result of the monitoring and verification system. The thought is that simply being compliant with IDEA does not equate to improving the results for children with disabilities.

This focused topic will include the following:
• It will be developed in conjunction with key stakeholders
• It will involve gathering and analyzing data to support informed decision making
• It may bring some OSEP resources to bear on the topic
• It will result in a change in practices related to the results of the topic
• Data will demonstrate improved results

In the webinar, OSEP’s representative continually made the point that the topic will be state driven, even though OSEP is mandating that this be done.

On the surface, this sounds like a good idea. However, it’s one of those things that breaks down when you get into the details.

Concepts like this come from something called Total Quality Management (TQM). TQM comes from manufacturing and the idea is to continuously improve the process of manufacturing so that output increases, mistakes decrease, and quality improves.

Outside of assembly lines it deals with identifying outcomes, measuring them, and basing decisions around improving them. Done over a period of time this theoretically results in continuous improvement of the organization. In other words, if you improve the results of the measurement that must mean you are doing a better job. You can see where this would work with an assembly line, but it breaks down outside of that. For example, improving test scores does not mean that children are better prepared for college or for work, it means they are better at taking those specific tests.

This is a concerning trend for two reasons. First, states are going to devote a lot of resources and staff to documenting that they are improving their outcomes. These resources could have been better spent providing and funding direct services. Second, states are going to focus their efforts, policies, and budgetary decisions around improving measurements and not about improving the lives of children.

I have provided links below to OSEP, IDEA, and the State Advisory Panel on Special Education. The advisory panel website has the power point for the webinar (it’s the May 20th webinar).

Links:
Office of Special Education Programs (OSEP): http://www2.ed.gov/about/offices/list/osers/osep/index.html

Individuals with Disabilities Education Act:
http://idea.ed.gov/

State Advisory Panels on Special Education:
http://www.stateadvisorypanel.org/

The Texas Department of Assistive and Rehabilitative Services is soliciting feedback to changes in the Texas Administrative Code regarding Early Childhood Intervention Services. These changes are in response to the budget situation in Texas and can be accessed here: http://www.dars.state.tx.us/ecis/2011_amendments.docx .

Below is the feedback that I submitted to DARS regarding these proposed changes.

This letter is in response to the solicitation for public comment on the proposed revisions to Title 40, Texas Administrative Code, Part 2, Chapter 108, Division for Early Childhood Intervention Services.

Let me begin by thanking DARS for the opportunity to provide feedback on this important matter. As I read this document and compare it to the current Texas Administrative Code, I feel that there are several significant changes:
1. Eligibility is tightened up.
2. Standardized assessment tools.
3. The family cost share is modified.

Eligibility:
The proposed changes significantly tighten the eligibility criteria for receiving ECI services. With regards to the changes to eligibility, DARS is aware that fewer children will be admitted to the program as a result. I have an obvious observation about this and two questions for clarification.

I understand this narrowing of eligibility is driven by the budget and that philosophical statements won’t help, but it is worth pointing out that children that don’t meet the new criteria will still be delayed and will still have needs, they just won’t be addressed as part of this program. If they are fortunate then their parents will have good insurance to help them. If they are not fortunate then their delays will be inherited by an already overtaxed public school system.

With regards to my questions: If a child is currently receiving services under the current Administrative Code but does not meet the new criteria, will they cease to receive services upon being re-evaluated? If so, does DARS have a communication plan in place to inform parents before the re-evaluation?

Assessment Tools:
The proposed changes require DARS ECI assessment tools, this language is not present in the current Administrative Code. As DARS is aware, there are pro’s and con’s to standardizing assessment tools. It allows for more “apples to apples” comparisons, especially if central training is mandated on the use of the assessment tools. The con’s are that every tool has inherit limitations, if the tools are not administered in the same manner by everyone then they become useless for making comparisons, and it’s possible that adopting these tools may create a financial burden to providers.

Will DARS be conducting the training on the assessment tools for providers? Does DARS feel that the adoption of the tools, combined with the training, will provide a financial burden on providers? Will this burden be forwarded to parents?

Family Cost Share:
The table below highlights the changes to the monthly fee for families based upon their family income expressed as a percentage of Federal poverty level (FPL). Basically the new cost share requires more families to pay for ECI services, either out of pocket of via third party payers (such as insurance companies). DARS needs to be aware that this may restrict the number of families that can access the services.

Current Family Income by % FPL Current Monthly Fee Proposed Family Income by % FPL Proposed Monthly Fee
<250% $0 <= 200% $0
>250% to <350% $20 >200% to 250% $10
>350% to <450% $50 >250% to 350% $20
>450% to <550% $75 >350% to 450% $55
>550% to <650% $100 >450% to 550% $85
>650% to <750% $125 >550% to 650% $115
>750% $150 >650% to 750% $145
>750% $175

Thank you again for giving me the opportunity to provide feedback regarding the proposed changes. I appreciate that DARS is attempting to offer these services in a time when the state’s budget situation gives DARS only bad choices.

In the May issue of Techniques for Track and Field and Cross Country , Scott Christensen has a thought provoking article looking at how athlete size has changed over the past 70 years.

The publication is for track and field coaches, but there is little data on the size of track and field athletes going back this far, as a result the author is analyzing the University of Nebraska’s offensive linemen. The results are interesting and are summarized in the table below.

1940

2009

Change
Weight (kg)

75

125

54.50%

Height (cm)

178

185

5%

BMI

25.2

35.32

40.20%

From 1940 until 2009, players have gotten noticeably heavier while not getting noticeably taller. In 1940, the heaviest lineman was 91 kg. In 2009, no offensive lineman weighed less than 111 kg and the heaviest one was 147 kg.

The author mathematically projects what will happen between 1940 and 2040 and predicts that at this rate, the players will increase in height by roughly 10% over this 100 year period, but their weights will almost double (i.e. their projection is that the average lineman will weigh 160 kg).

The news that today’s athletes are larger should not be surprising, especially in the sport of American football. Players are larger, stronger, and faster. There are a number of factors at play here. First, nutrition is better – this probably accounts for the increase in height seen over the last 70 years. This is both in terms of nutrition for infants/children as well as performance nutrition for athletes. The better nutrition also allows athletes to get better results from their training. Second, training is more sophisticated than it was 70 years ago. As a result of better strength and conditioning combined with nutrition, athletes are able to put on a lot more muscle mass.

Is this a good thing? There are two concerns with the increased body size; injuries and health complications from the weight.

With regards to injuries, today’s players are larger, stronger, and faster. In American football, this means more powerful collisions. This should result in more injuries to athletes. Is this occurring? A 2007 article in the Journal of Athletic Training looked at injuries from 1988/1989 through 2003/2004 in American football and found that despite the improved strength and conditioning programs (and the increase in athlete size and strength) the injury rates in NCAA football are largely unchanged during this 16 year period (roughly 35 injuries per 1000 athlete exposures).

The larger concern is that the increased weight results in a higher body mass index. As you can see from the table above, this has increased by over 40% during the last 70 years. Now, BMI assumes a sedentary person. For example, a 6’ tall, 200 pound person with 30% body fat and a 6’ tall, 200 pound person with 5% body fat will have identical BMI’s, so this always needs to be kept in perspective.

Clearly, American football players will have a greater muscle mass than sedentary individuals. The problem is that a BMI of 30 puts someone into the obese category. In terms of health, the amount of muscle mass may not matter much. This is because larger athletes are putting larger oxygen demands on their hearts and larger demands on their joints, both of which could contribute to health issues later in life. Combine this with the fact that the diet required to put on and maintain this much extra weight will probably not be conducive to long term cardio-vascular health and the future might be concerning.

The author has a through-provoking article. It doesn’t seem (at least in NCAA football) that the injury rate has increased since 1988, but it’s also unclear if the trend in heavier athletes is good for their long-term health after athletics.

Christensen, S. (2011). Size in athletic performance. Techniques for Track and Field and Cross Country, 4(4): 43-48.

Dick, R., Ferrara, M.S., Agel, J., Courson, R., Marshall, S.W., Hanley, M.J., and Reifsteck, F. (2007). Descriptive epidemiology of collegiate men’s football injuries: National Collegiate Athletic Association Injury Surveillance System, 1988-1989 through 2003-2004. Journal of Athletic Training, 42(2): 221-234.