Monday, December 21, 2009

UV protection for eyes

UV radiation from the sun can damage not only the skin of your eyelids but also the clear outer parts of the eye — the cornea and conjunctiva. UV exposure also contributes to the development of certain types of cataracts.

When you're choosing sunglasses, look for UV protection details on product labels. Choose sunglasses that block at least 99 percent of UVB rays and at least 95 percent of UVA rays. This level of UV protection is in accordance with guidelines established by the American National Standards Institute (ANSI). Skip sunglasses that are labeled "cosmetic" and those that don't offer details on UV protection.

Of course, UV protection isn't the only consideration when it comes to selecting sunglasses. In addition to UV protection — which, again, is a must for any type of sunglasses — here's the lowdown on other options:

  • Blue-blocking lenses. Blue-blocking lenses — which are typically yellow or orange — are thought to make distant objects easier to see, especially in low light. Blue-blocking plastic lenses may make it difficult to discriminate the hues in traffic lights, however, and not all blue-blocking lenses offer adequate UV protection.

  • Polarized lenses. Polarized lenses reduce glare. Unless they're specifically treated with UV coating, polarized lenses don't offer UV protection.

  • Photochromic lenses. Photochromic lenses reduce glare and help maintain clarity, although they may take time to adjust to different light conditions. Not all photochromic lenses offer adequate UV protection, so be sure to check the product label.

  • Polycarbonate lenses. Polycarbonate lenses offer protection from impact injuries that may be sustained during physical activities. Polycarbonate lenses also adequately shield the eyes from UV radiation.

  • Mirror-coated lenses. Mirror-coated lenses help block visible light, but they don't necessarily block UV radiation.
Standard prescription eyeglasses can also be treated with a material that provides UV protection while retaining a clear, nontinted appearance. Most rigid contact lenses also provide UV protection — but because contact lenses don't cover the entire eye, it's still important to wear sunglasses when you're outdoors.

Source : Dennis Robertson, M.D. Mayo Clinic Emeritus Opthomologist

Caffeine limits blood flow to heart muscle during exercise

In healthy volunteers, the equivalent of two cups of coffee reduced the body's ability to boost blood flow to the heart muscle in response to exercise, and the effect was stronger when the participants were in a chamber simulating high altitude, according to a new study in the Jan. 17, 2006, issue of the Journal of the American College of Cardiology.

"Whenever we do a physical exercise, myocardial blood flow has to increase in order to match the increased need of oxygen. We found that caffeine may adversely affect this mechanism. It partly blunts the needed increase in flow," said Philipp A. Kaufmann, M.D., F.A.C.C., from the University Hospital Zurich and Center for Integrative Human Physiology CIHP in Zurich,.

The researchers, including lead author Mehdi Namdar, M.D., F.A.C.C., studied 18 young, healthy people who were regular coffee drinkers. The participants did not drink any coffee for 36 hours prior to the study testing. In one part of the study, PET scans that showed blood flow in the hearts of 10 participants were performed before and immediately after they rode a stationary exercise bicycle. In the second part of the study, the same type of myocardial blood-flow measurements were done in 8 participants who were in a chamber simulating the thin air at about 15,000 feet (4,500 meters) altitude. The high-altitude test was designed to mimic the way coronary artery disease deprives the heart muscle of sufficient oxygen. In both groups, the testing procedure was repeated 50 minutes after each participant swallowed a tablet containing 200 milligrams of caffeine, the equivalent of two cups of coffee.

The caffeine dose did not affect blood flow within the heart muscle while the participants were at rest. However, the blood flow measurements taken immediately after exercise were significantly lower after the participants had taken caffeine tablets. The effect was pronounced in the group in the high-altitude chamber.

Blood flow normally increases in response to exercise, and the results indicate that caffeine reduces the body's ability to boost blood flow to the muscle of the heart on demand. The ratio of exercise blood flow to resting blood flow, called the myocardial flow reserve, was 22 percent lower in the group at normal air pressure after ingesting caffeine and 39 percent lower in the group in the high-altitude chamber. Dr. Kaufmann said that caffeine may block certain receptors in the walls of blood vessels, interfering with the normal process by which adenosine signals blood vessels to dilate in response to the demands of physical activity.

"Although these findings seem not to have a clinical importance in healthy volunteers, they may raise safety questions in patients with reduced coronary flow reserve, as seen in coronary artery disease, particularly before physical exercise and at high-altitude exposure," the researchers wrote.

Although caffeine is a stimulant, these results also indicate that coffee may not necessarily boost athletic performance.

"We now have good evidence that, at the level of myocardial blood flow, caffeine is not a useful stimulant. It may be a stimulant at the cerebral level in terms of being more awake and alert, which may subjectively give the feeling of having better physical performance. But I now would not recommend that any athlete drink caffeine before sports. It may not be a physical stimulant, and may even adversely affect physical performance," Dr. Kaufmann said. "It may not be as harmless as we thought before, particularly if you suffer from coronary artery disease or if you are in the mountains."

Dr. Kaufmann noted that this study was not designed to measure athletic performance.

Although the participants were all healthy, Dr. Kaufmann said that the results raise concerns about possible effects of caffeine in people with heart disease.

"Any advice would be based on results of healthy volunteers and would be a bit speculative; nevertheless, my advice would be: do not drink coffee before doing physical activities. We hope to be able to provide data soon on the situation of patients with coronary artery disease," he said.

The researchers noted that other studies of coffee and heart disease have produced mixed results.

Although this study included only 18 participants, the researchers said that the differences they saw were large enough for them to be confident that the effect of caffeine on heart muscle blood flow is real. They pointed out that longer studies of people with heart disease will be needed in order to understand whether the blood flow effects have important health consequences.

Thomas H. Schindler, M.D. from the David Geffen School of Medicine at UCLA in Los Angeles, California, who was not connected with this study, said that if the results are confirmed, they could have important implications.

"In particular, this may play an important role in patients with obstructive coronary artery disease in the intermediate range between 50 percent and 85 percent narrowing of the epicardial luminal diameter. In this range of coronary artery disease-induced epicardial narrowing, the myocardial flow reserve (MFR) has been widely assumed to compensate for the epicardial narrowing and, thereby, to preserve the myocardial blood flow to the heart. A further reduction of the MFR, for example owing to caffeine intake, therefore could precipitate stress-induced myocardial ischemia, angina pectoris (reflecting an imbalance between myocardial oxygen supply and demand) or could also contribute to the manifestation of acute coronary syndromes. Consequently, as stated by Namdar et al., the current findings indeed raise safety questions in patients with already reduced MFR as seen in coronary artery disease, particularly before physical exercise and at high-altitude exposure," Dr. Schindler said.

Dr. Schindler said that further studies will be needed to answer the important questions raised by this study.

Source: amy murphy /american college of cardiology/ photo from

Thursday, December 17, 2009

Luddite, no more...

I have recently installed a GPS onto my bike, i.e. Garmin GPSMap 60CsX. It might not be as cool as the Edge 705 or the touchscreen Oregon, but this handheld GPS is super fast in connecting with the satellites. One of its advantages is its dedicated button which provide easier & faster access to its functions. I have customised the display to show the speed, trip distance, moving time, stopping time, highest speed, moving average speed, elevation & odometer. In different page, it also show the road/topo map, compass & track profile.

I really love the road map because I don't have to stop to look at the map to find my way. With the Zoom In & Zoom Out button pressed, it's so easy to negotiate my way while cycling. And after my ride, I just hooked it to my notebook and view my trip using the Google Earth.

Garmin is a reliable name in the GPS market. In fact, I have used its e-Trex handheld unit since 8 years ago which doesn't have any installed map but good in tracking & marking waypoints. I'm also using the Nuvi 255W which I think is the best car GPS navigation system! It's so easy to drive around foreign roads by just listening to the direction by Karen the Australian female voice. (love the Australian accent when pronouncing the local roads' name!)

No one can deny the usefullness and practicality of GPS when travelling whether cycling, hiking or driving. And I have no doubt that this GPS handheld will be very handy during my in-coming Manali~Leh Tour.

Friday, December 11, 2009

Manali-Leh-Khardung La Tour

For the last few weeks I have been busy gathering information about this famous route on the Himalaya. The best information I got if from Laura Sloane's Himalaya By Bike book that provides details of the route including its maps and profiles. The details in the book are so informative and updated. So I guess, I will be making only some copies to bring along on the tour to cut down the weight. ha ha..

The plan is to fly to Delhi, travel by bus to Manali, acclimatize, super slow ride to Leh for 6-7 days, ride up to Khardung La and back, and fly back to Delhi. I'm yet to study in details but hope that the whole trip/ tour can be done in 2 weeks' time. Preferably in July-August 2010 before the month of Ramadan.

So far 2 of my other buddies are keen to join me. But our main concern will be the AMS. We might have climbed few 7,000ft high mountains but we have never done any high altitude bike touring before. The Manali-Leh-Khardung La is climbing from 6,000ft to 18,000ft high over 500km of winding, narrow and some bad roads. But in July, I think the weather will be warmer and it is more suitable for us. From my past winter ride experience, I will definitely try to avoid the snow again!

It will be an unsupported bike tour on hardtail, will travel light with a bar bag & panniers.

We will sleeping in tent and accomodations available along the way as it's not expensive. The food is fine with us as we are used to eating north indian food- pakoras, chapati, chai, rice, dhal etc.

In the meantime, I will spend time getting more informations, studying the details and continue our training. So... Himalaya, Here We Come!

Source: photo from himalaya by bike, &

Established in December 2006