Wednesday, June 29, 2011

Study on soccer: Women get up faster


Interruptions are frequent in football: Football players (m/f) spend on average 38 percent of the total game time not chasing the ball. This was established by sports scientists from the Chair of Training Science and Sports Informatics at TUM in a study of 56 football games. In some games, the interruptions took up as much as 53% of the time, thus exceeding the duration of the actual sports activity.

In sum, interruptions in men's and women's football are about the same. The individual interruptions, though, are significantly longer in men's football. Cheering a goal, for instance, takes almost a full minute with men, while women only cheer half as long. At 45 seconds, substitutions in men's football take almost 10 seconds longer than in women's football. Particularly striking are the differences in the duration of injury interruptions – the stronger sex remains on the ground 30 seconds longer. Overall, when women play, interruptions are more frequent, but the game generally resumes much faster than with men.

TUM sports scientist Prof. Martin Lames explains: "In general the differences can be interpreted as follows: For men the thought of staging themselves is much more pronounced than for women, where the game itself is obviously paramount." Pulling off a show, play-acting and protesting are more typical of men. Lames: "The reason for this could be that men's football generally pulls in more spectators and receives greater media coverage."

Malte Siegle, doctoral candidate at the Chair, adds: "We can even provide evidence that men use interruptions tactically. As many fans have conjectured, when they are in the lead, players take their time with injuries. Much more so than if the score is even, or when the other side is leading. This behavior cannot be observed in women's football."

Prof. Martin Lames's team of researchers at the Chair of Training Science and Sports Informatics is using the method of "Case-by-Case Analysis of Game Interruptions", which they developed, to cast light on how football games are structured. The results will help the scientists determine how football players (m/f) might best prepare for a game. The comparison between women's and men's football was actually the byproduct of a research project.

The Women's World Cup, which just started in Germany, will show whether or not these differences will persist in light of the fact that women's football is enjoying increasing numbers of spectators and growing media attention.

Thursday, June 16, 2011

Shorter warm-ups of lower intensity are better


Coaches, physiologists and athletes alike will attest to the importance of warming up before athletic competition. Warming up increases muscle temperature, accelerates oxygen uptake kinetics and increases anaerobic metabolism, all of which enhance performance. However, the question of how long and strenuous a warm-up should be is more contentious, with some in the sports community advocating longer warm-ups and others espousing shorter ones. Now researchers at the University of Calgary Human Performance Laboratory in Calgary, Alberta, Canada have found evidence indicating that less is more.

In a study comparing the effects of a traditional, intense warm-up with those of a shorter, less strenuous warm-up on the performance of 10 highly trained track cyclists, the researchers found that the shorter warm-up produced less muscle fatigue yet more peak power output. The findings are captured in the study entitled, “Less is More: Standard Warm-up Causes Fatigue and Less Warm-up Permits Greater Cycling Output,” published in the Journal of Applied Physiology. The study was conducted by Elias K. Tomaras and Brian R. MacIntosh.

The Long and Short of It

The intensity of traditional, longer warm-ups has been thought to offer competitive athletes an edge by promoting a process called post-activation potentiation (PAP). In PAP, brief bouts of strenuous physical activity produce a biochemical change in muscle cells that can enhance muscle contractile response. The phenomenon usually lasts from 5 to 10 minutes. However, as the researchers note, fatigue can decrease muscle contractile response. Therefore, the team focused analysis on muscle contractile response as well as on another key component of a cyclist's success, peak power output.

In the study, cyclists participated in two warm-ups. A longer, traditional warm-up began with 20 minutes of cycling that gradually increased in intensity until the cyclists reached 95 percent of their maximal heart rates. This general warm-up was followed by four sprints at 8-minute intervals. The entire warm-up lasted approximately 50 minutes total. The shorter, experimental warm-up included a shorter initial ride that increased in intensity until the cyclists reached only 70 percent of their maximal heart rates. This warm-up ended with only one sprint and lasted approximately 15 minutes.

The researchers used specific tests to measure the cyclists’ muscle contractile response and peak power output before, during and after the warm-ups. Although they theorized that both warm-ups would elicit PAP, they also theorized that the traditional warm-up would generate enough fatigue to counteract PAP, whereas the experimental warm-up might not. They found that although muscle contractile response decreased more after the traditional warm-up, indicating greater fatigue, there was a decrease in contractile response after both warm-ups. This, according to Tomaras, a co-author, “indicates that an even shorter warm-up might be better for athletes who want to tap into PAP.”

The shorter warm-up permitted better performance, as well. Peak power output was 6.2 percent higher and total work was 5 percent higher after the experimental warm-up than after the traditional warm-up, results the researchers say are significant, and could make a substantial difference in competitive events.


The fitness community has embraced PAP as a competitive strategy in recent years. As word spreads about PAP’s benefits, trainers and coaches have attempted to time PAP to coincide with competition. But the Calgary team’s findings suggest too much focus on promoting PAP could be self-defeating, as starting the process requires intense, but tiring, bursts of activity. In their conclusion, the researchers write, “A warm-up that is performed at too high of an intensity for longer than necessary can result in fatigue and impair subsequent athletic performance.”

Instead, according to co-researcher MacIntosh, “the findings suggest that competitive athletes may reap greater rewards from PAP by engaging in less strenuous warm-up than conventional wisdom dictates. A better approach would be to aim for just enough activity to promote PAP without creating fatigue”.

This may be especially true for sprint athletes (cyclists, relay runners, track sprinters, swimmers), whose competition involves several events close together. The researchers conclude, “If warm-up results in fatigue of an athlete and impairs performance in a single subsequent bout of exercise, what impact would it have on multiple performances required on the same day?”

Thursday, June 2, 2011

Stronger hips improved running mechanics, lessened knee pain


Hip strengthening exercises performed by female runners not only significantly reduced patellofemoral pain -- a common knee pain experienced by runners -- but they also improved the runners' gaits, according to Indiana University motion analysis expert Tracy Dierks.

"The results indicate that the strengthening intervention was successful in reducing pain, which corresponded to improved mechanics," said Dierks, associate professor of physical therapy in the School of Health and Rehabilitation Sciences at Indiana University-Purdue University Indianapolis. "The leg was going through more motion, suggesting that the (pain) guarding mechanism was reduced, and coordination or control of many of these peak or maximum angles in the leg were improved in that they were getting closer to occurring at the same time."

Only in recent years have researchers begun studying the hips as a possible contributor to patellofemoral pain (PFP). This study is the first to focus on hip strength and gait changes during prolonged running. Dierks, director of the Motion Analysis Research Laboratory at IUPUI, discussed his findings on Wednesday at the American College of Sports Medicine annual meeting in Denver.

The runners in Dierks' study received no training or coaching on proper running form, which makes the improvements more notable. The improvements in mechanics resembled those of uninjured runners, when muscles, joints and limbs move economically and in synch with each other.

About the study

The study involved four runners and a control group comprised of another four runners. Hip strength measurements and kinematic data -- minute measurements of how the women's hips, knees and shin bones moved and rotated while they ran -- were taken before and after the runners in the control group maintained their normal running schedule for six weeks. The measurements were repeated for all of the runners before and after the next six-week period in which they all performed the hip-strengthening exercises.

The exercises, performed twice a week for around 30 to 45 minutes, involved single-leg squats and exercises with a resistance band, all exercises that can be performed at home. This study is part of an ongoing study involving hip exercises and PFP pain, with 10 runners successfully using the intervention.

After the six-week program, the movement of the hips and knees in relation to each other improved for both groups of runners, demonstrating increases in joint angles between the foot, shin and thigh.

The study used a pain scale of zero to 10, with 3 representing the onset of pain and 7 representing very strong pain -- the point at which the runners normally stop running because the pain is too great. The injured runners began the six-week trial registering pain of 7 when they ran on a treadmill and finished the study period registering pain levels of 2 or lower; i.e. no onset of pain.

PFP, one of the most common running injuries, is caused when the thigh bone rubs against the back of the knee cap. Runners with PFP typically do not feel pain when they begin running, but once the pain begins, it gets increasingly worse. Once they stop running, the pain goes away almost immediately. Dierks said studies indicate PFP essentially wears away cartilage and can have the same effect as osteoarthritis. His study participants showed many of the classic signs of PFP, the most prominent being their knees collapsing inward when running or doing a squat exercise move.

Athletes competing against an opponent wearing red are more likely to lose

A new study, published in the latest issue of the journal Emotion, finds that when humans see red, their reactions become both faster and more forceful. And people are unaware of the color's intensifying effect.

The findings may have applications for sporting and other activities in which a brief burst of strength and speed is needed, such as weightlifting. But the authors caution that the color energy boost is likely short-lived.

"Red enhances our physical reactions because it is seen as a danger cue," explains coauthor Andrew Elliot, professor of psychology at the University of Rochester and a lead researcher in the field of color psychology. "Humans flush when they are angry or preparing for attack," he explains. "People are acutely aware of such reddening in others and it's implications."

But threat is a double-edged sword, argue Elliot and coauthor Henk Aarts, professor of psychology at Utrecht University, in the Netherlands. Along with mobilizing extra energy, "threat also evokes worry, task distraction, and self-preoccupation, all of which have been shown to tax mental resources," they write in the paper. In earlier color research, exposure to red has proven counterproductive for skilled motor and mental tasks: athletes competing against an opponent wearing red are more likely to lose and students exposed to red before a test perform worse.

"Color affects us in many ways depending on the context," explains Elliot, whose research also has documented how men and women are unconsciously attracted to the opposite sex when they wear red. "Those color effects fly under our awareness radar," he says.

The study measured the reactions of students in two experiments. In the first, 30 fourth-through-10th graders pinched and held open a metal clasp. Right before doing so, they read aloud their participant number written in either red or gray crayon. In the second experiment, 46 undergraduates squeezed a handgrip with their dominant hand as hard as possible when they read the word "squeeze" on a computer monitor. The word appeared on a red, blue, or gray background.

In both scenarios, red significantly increased the force exerted, with participants in the red condition squeezing with greater maximum force than those in the gray or blue conditions. In the handgrip experiment, not only the amount of force, but also the immediacy of the reaction increased when red was present.

The colors in the study were precisely equated in hue, brightness, and chroma (intensity) to insure that reactions were not attributable to these other qualities of color. "Many color psychology studies in the past have failed to account for these independent variables, so the results have been ambiguous," explains Elliot.
The study focused exclusively on isometric or non-directional physical responses, allowing the researcher to measure the energy response of participants, though not their behavior, which can vary among individuals and situations. The familiar flight or fight responses, for example, show differing reactions to threat.