Newswise — Exercise Training and Food Reward

A perceived barrier for engaging in exercise is its potential to promote hedonic (reward-driven) eating. Food reward plays an important role in weight management because it is influenced by biological signals from the body as well as cues from the environment that encourage eating. To study factors related to hedonic control over eating (i.e., binge eating and food reward), investigators randomly assigned 46 overweight or obese women and men to 12 weeks of moderate-to-vigorous exercise training or to a non-exercising control group. Exercise training resulted in a reduction in wanting (i.e., the motivational desire to eat food), with no change in liking (i.e., pleasantness of food) high fat foods. Improvement in binge eating scores was also related to reduction in body fat. These findings suggest that hedonic eating does not counteract the benefit of physical activity in obesity management. Rather, exercise appears to result in beneficial changes in factors related to improved appetite control, as well as small, but clinically meaningful, reductions in weight and waist circumference. Read the article.


Baby Steps for Mother's Cardiovascular Health

During pregnancy, positive changes must occur in the mother’s blood vessels to increase delivery of oxygen and nutrients to the growing fetus. Since physical activity is associated with improvement in blood vessel health in the general population, investigators examined how physical activity affects blood vessel health in 70 healthy women during their third trimester of pregnancy. They monitored activity levels and assessed blood vessel health and blood sugar control for one week. Blood vessel health was measured using flow mediated dilation (FMD), which determines how much a blood vessel widens in response to an increase in blood flow through the artery. Pregnant women meeting or exceeding current physical activity guidelines (150 minutes per week of moderate-intensity exercise) had improved FMD and blood sugar control compared to pregnant women not meeting the guidelines. These results indicate that prenatal exercise may decrease the common risk of developing high blood pressure during pregnancy. View the abstract.


Does Intensity Matter when Replacing Sitting Time with Physical Activity?

Modern societies spend too much time sitting. Although replacing excess sedentary time with physical activity has received increased attention in chronic disease prevention programs, questions still remain. Is it enough to replace sedentary time with light-intensity physical activity (e.g. standing up and pottering around)? Is additional benefit gained by employing more intense activity (e.g. purposeful walking)? Over a 12-month period, this study followed 647 adults at high risk of developing diabetes to observe how changes in physical activity are related to changes in markers of cardiovascular and metabolic health (blood pressure, fat and sugar in the blood, waist size). Just over a third of the sample reduced their sedentary behavior by five minutes or more. While those that replaced some of their sedentary time with light-intensity physical activity improved their health, greater gains were seen when the sedentary time was replaced by activity that was of at least moderate intensity (e.g. purposeful walking). Replacing just 30 minutes of sedentary time with moderate-intensity physical activity was associated with health benefits similar to those associated with replacing 105 minutes of sedentary time with light-intensity physical activity. View the abstract.


Is Muscle Mass Lost During Hospitalization of Elderly Patients and Can It Be Prevent with Exercise?

Loss of muscle mass during hospitalization may produce severe consequences in elderly patients, who often already have functional impairments. In this study, the investigators examined 13 geriatric patients (aged 69-94 years) with dual-energy x-ray absorptiometry (DEXA) scans at the beginning and end of their hospital stay. During hospitalization, the investigators used electrical stimulation for 30 minutes every day for 6-7 days to stimulate muscle contraction of the thigh muscles of only a single leg. Interestingly, a loss of lean tissue mass (about 2.5%) was observed in the non-stimulated leg while lean tissue was maintained in the leg receiving electrical stimulation. Although lean tissue also includes water, the difference in mass between the legs that did and did not receive stimulation most likely reflects a difference in muscle protein content. In muscle biopsies collected from 9 of the patients, the investigators observed a positive effect of electrical stimulation, particularly in genes related to breakdown of muscle proteins. The authors suggest that these results demonstrate the positive effect of exercise on the muscle of geriatric patients, even when hospitalized due to illness. Read the article.