LONG WARM-UPS FOR TRACK AND FIELD CAN SABOTAGE RACE PERFORMANCE
ScienceDaily (May 29, 2011) - Low intensity warm-ups enhance athletic performance and long warm-ups can sabotage it. University of Calgary Faculty of Kinesiology researcher Elias Tomaras says the idea came to him while watching track and field sprinters warm-up for a race. "If you watch sprinters, short distance speed skaters or cyclists before their race, they will often warm-up for one to two hours, including several brief bouts of high intensity exercise. From an exercise physiology point of view, it seemed like it might be pretty tiring."
Many coaches and physiologists believe that a longer warm up provides an increase in muscle temperature, acceleration of oxygen uptake kinetics, increased anaerobic metabolism and a process called post-activation potentiation of the muscles. However, very few studies have studied if warm ups has a detrimental effect on performance.
As it turns out, the warm-up is one of the more contentious issues in high-performance sport. Different coaches have different theories and not a lot of quality research has been done to identify the optimal warm-up. Tomaras' study, published recently in the Journal of Applied Physiology suggests that at the very least, athletes may want to lower the intensity and reduce the amount of time that they warm up.
"Our study compared a standard warm-up, with what we termed an experimental warm-up," explains Tomaras. "We interviewed a number of coaches and athletes to come up with the traditional warm-up."
The experiment involved high performance sprint cyclists performing a traditional warm-up lasting about 50 minutes with a graduated intensity that ranged from 60 to 95 per cent of maximal heart rate before ending with several all-out sprints. The experimental warm-up was much shorter at about 15 minutes, and was performed at a lower intensity, ending with just a single sprint. The researchers conducted a number of tests following each warm-up to accurately measure the athlete's power output and fatigue.
"What we found, was that the shorter warm-up resulted in significantly less muscle fatigue and a peak power output that was 6.2 per cent higher. This represents a substantial improvement for an elite athlete," says Tomaras. "On the basis of this study I would suggest that sprint athletes should start thinking about adopting a shorter and less strenuous warm up for better performance."
GENETIC CHANGES BEHIND SWEET TOOTH
ScienceDaily (Apr. 4, 2011) - The substance ghrelin plays an important role in various addictions, such as alcoholism and binge-eating. It also impacts on sugar consumption, which is due, in part, to genetic factors, reveals new research from the University of Gothenburg, Sweden.
Ghrelin is a neuropeptide that both activates the brain's reward system and increases appetite. This means that when we are hungry, levels of ghrelin increase, activating the brain's reward system, and this, in turn, increases our motivation to look for food. Previous research from the Sahlgrenska Academy has linked ghrelin to the development of various dependencies, such as drug addiction and alcoholism.
In a new study published in the online journal PLoS ONE, researchers examined the genes of 579 individuals chosen from the general public. It emerged that people with certain changes in the ghrelin gene consume more sugar than their peers who do not have these changes. This link was also seen in people who consumed large amounts of both sugar and alcohol.
Trials have also been carried out using rats, where the researchers found that when ghrelin was blocked the rats reduced their consumption of sugar and were less motivated to hunt for sugar.
"This shows that ghrelin is a strong driver when it comes to tracking down rewarding substances such as sugar or alcohol," says researcher Elisabet Jerlhag from the Sahlgrenska Academy's Department of Pharmacology.
These results go hand in hand with the researchers' previous findings which showed that substances that block the ghrelin system reduce the positive effects of addictive drugs and that changes in the ghrelin gene are associated with high alcohol consumption, weight gain in alcoholics and smoking.
The researchers are now a step closer to understanding what happens in the brain and the body in different types of addictive behavior. Understanding these mechanisms means that new drugs can be developed to block the ghrelin system and used to treat patients who are addicted to alcohol or who suffer from binge-eating disorders.
"This knowledge could also make it easier for society to view dependency as an illness and could mean that these people can get the treatment they need more readily," says Jerlhag
NEW IMAGING TECHNOLOGY PROMISING FOR DIAGNOSING CARDIOVASCULAR DISEASE, DIABETES
Science Daily (June 10, 2011) - Researchers have developed a new type of imaging technology to diagnose cardiovascular disease and other disorders by measuring ultrasound signals from molecules exposed to a fast-pulsing laser.
The new method could be used to take precise three-dimensional images of plaques lining arteries, said Ji-Xin Cheng, an associate professor of biomedical engineering and chemistry at Purdue University.
Other imaging methods that provide molecular information are unable to penetrate tissue deep enough to reveal the three-dimensional structure of the plaques, but being able to do so would make better diagnoses possible, he said.
"You would have to cut a cross section of an artery to really see the three-dimensional structure of the plaque," Cheng said. "Obviously, that can't be used for living patients." The imaging reveals the presence of carbon-hydrogen bonds making up lipid molecules in arterial plaques that cause heart disease. The method also might be used to detect fat molecules in muscles to diagnose diabetes and for other lipid-related disorders, including neurological conditions and brain trauma. The technique also reveals nitrogen-hydrogen bonds making up proteins, meaning the imaging tool also might be useful for diagnosing other diseases and to study collagen's role in scar formation.
"Being able to key on specific chemical bonds is expected to open a completely new direction for the field," Cheng said.
Findings are detailed in a paper to be published in Physical Review Letters and expected to appear in the June 17 issue. The findings represent the culmination of four years of research led by Cheng and doctoral student Han-Wei Wang.
The new technique uses nanosecond laser pulses in the near-infrared range of the spectrum. The laser generates molecular "overtone" vibrations, or wavelengths that are not absorbed by the blood. The pulsed laser causes tissue to heat and expand locally, generating pressure waves at the ultrasound frequency that can be picked up with a device called a transducer.
"We are working to miniaturize the system so that we can build an endoscope to put into blood vessels using a catheter," Cheng said. "This would enable us to see the exact nature of plaque formation in the walls of arteries to better quantify and diagnose cardiovascular disease."
Lihong Wang, Gene K. Beare Distinguished Professor of Biomedical Engineering at Washington University in St. Louis, is a pioneer of using the "photo-acoustic" imaging of blood vessels based on the absorption of light by the electrons in hemoglobin.
The Purdue researchers are the first to show that a strong photo-acoustic signal can arise from the absorption of light by the chemical bonds in molecules. The near-infrared laser causes enough heating to generate ultrasound but not enough to damage tissue.
"You can measure the time delay between the laser and the ultrasound waves, and this gives you a precise distance, which enables you to image layers of the tissues for three-dimensional pictures," Cheng said. "You do one scan and get all the cross sections. Our initial target is cardiovascular disease, but there are other potential applications, including diabetes and neurological conditions."
The approach represents a major improvement over another imaging technique, called coherent anti-Stokes Raman scattering, or CARS, which has been used by the Purdue-based lab to study three-dimensional plaque formation in arteries.
Also leading the research are Michael Sturek, chair of the Department of Cellular and Integrative Physiology at the Indiana University School of Medicine; Robert P. Lucht, Purdue's Ralph and Bettye Bailey Professor of Combustion in Mechanical Engineering; and David Umulis, a Purdue assistant professor of agricultural and biological engineering. Other authors of the paper include Purdue graduate students Ning Chai, Pu Wang and Wei Dou and Washington University postdoctoral researcher Song Hu.
Findings are based on research with pig tissues in laboratory samples and also with live fruit flies. "You can see fat inside fly larvae, representing the potential to study how obesity affects physiology in humans," Cheng said
