Health reporting often focuses on breakthroughs, but scientific research progresses in gradual increments. Here’s a look back at five stories Jockology has covered in the last two years, with an update on the progress of related research since then.
The perils of sitting
The background: Sitting behind a desk all day without moving is bad for your health. Over the past few years, researchers have linked prolonged sedentary time with elevated risk of conditions such as heart disease, diabetes, and cancer. And the risks are independent of how much exercise you do, so you can’t undo the damage by hitting the gym. Experts advise breaking up your work day with short periods of movement, but it’s not clear how much is needed.
The update: In a study published in Medicine & Science in Sports & Exercise, researchers at Indiana University asked volunteers to sit still for three hours and recorded their endothelial function. This is a measure of how blood vessels expand and contract in response to changing blood flow, and serves as a sensitive early warning for heart-disease risk. As expected, endothelial function worsened after the first hour of sitting. But when the volunteers walked for five minutes at a very slow pace once an hour, the negative effect was completely eliminated. This suggests that it doesn’t take much to break up your sitting time.
The case against antioxidants
The background: Antioxidants such as vitamins C and E are popular with athletes, since they neutralize the potentially damaging free radicals produced by your cells during exercise. But a series of recent studies has found that taking antioxidant supplements seems to blunt the effect of endurance exercise. Researchers speculate that free radicals actually serve as signals that tell your body to adapt and get stronger, so if you neutralize them you get less of a fitness boost from the same workout.
The update: While most of the research has focused on endurance exercise, a Norwegian study published in the Journal of Physiology monitored 32 subjects who received either 1,000 milligrams of vitamin C and 235 mg of vitamin E or a placebo daily during a 10-week strength-training program. Markers of cellular signalling involved with muscle growth and repair were lower in the antioxidant group, as were strength gains. Unless you have a deficiency, the researchers suggest you should stick to getting your antioxidants from food rather than high-dose supplements.
The knock on running
The background: Running will ruin your knees, right? That’s a common belief, but study after study has found that long-term runners are, if anything, less likely to develop knee osteoarthritis than non-runners. One key factor is that runners tend to weigh less than non-runners, reducing mechanical load on the knee and minimizing the joint-damaging inflammatory hormones secreted by fat tissue. But biomechanists still find it surprising that running doesn’t take more of a toll on the knee.
The update: Researchers from Queen’s University analyzed the biomechanics of a group of volunteers to calculate knee-loading forces during walking and running. As expected, peak load for each stride was three times greater for running than for walking. But since you touch the ground only briefly and cover more ground with each stride while running, the total knee load per kilometre – a more relevant metric, the researchers argue – was actually the same for running and walking. And last month, yet another study with more than 2,000 participants found that runners were less likely to develop knee osteoarthritis than non-runners. Run on without fear.
The mystery of low iron
The background: Endurance athletes are notoriously prone to iron deficiency, in part because they have a greater number of iron-hungry red blood cells. This means they can have normal hemoglobin levels (the usual way of assessing whether someone is anemic) but low ferritin levels, which indicates they have suboptimal iron reserves stored in their bone marrow. This condition has its own name, iron deficiency non-anemia (IDNA), but research has produced conflicting results about whether sufferers with normal hemoglobin actually benefit from iron supplementation.
The update: A review in the British Journal of Sports Medicine combined the results of 17 studies with a total of 443 participants with IDNA. As expected, both oral iron supplements and iron injections increased ferritin levels. More importantly, supplementation produced a moderate increase in hemoglobin levels and aerobic endurance, even though the subjects already had normal hemoglobin levels. Further research is needed to figure out what the threshold for low ferritin is (the study used 35 nanograms per millilitre), but if you have unexplained fatigue and low ferritin, consider, in consultation with your doctor, trying iron supplements.
The culprit behind knee pain
The background: When your knee hurts, you figure there must be something wrong with your knee. But a growing body of research has linked weak hips with knee pain in runners, suggesting that the best way to get rid of runner’s knee is to strengthen your hips. A few initial studies offered encouraging results, but no study had directly compared the results of strengthening the muscles around the hip versus the muscles around the knee.
The update: Reed Ferber, of the University of Calgary, along with colleagues in Chicago, Milwaukee and Georgia state, randomly assigned 199 patients with knee pain to six weeks of either hip or knee strengthening, publishing the results last month in the Journal of Athletic Training. On average, the hip-strengthening group reported feeling better after three weeks, while the knee-strengthening group improved after four weeks. Both options look pretty good, which suggests that if you want to avoid knee pain in the first place, hip strengthening should be part of your plan.