How to Break Up Sedentary Behavior Optimally to Enhance Mood

Newswise — Sitting is the new smoking. Scientific studies have shown that breaking up long sitting periods with physical activity is necessary to improve both physical and mental health. However, it is unclear how often, how intense or how long those activity breaks should be. In this study, investigators conducted an Ecological Momentary Assessment (EMA) study in 92 university employees over five days. Participants’ physical behavior was captured continuously via accelerometers, and mood was assessed multiple times per day with smartphone diaries. Activity break intensity was positively associated with subsequent valence, energetic arousal and calmness. Break frequency was positively associated with subsequent valence and energetic arousal; break duration was not associated with mood, which means that longer breaks are not necessarily more beneficial. Moreover, results indicate that breaking up sedentary behavior was more beneficial at home than at work. Official public health recommendations aiming to minimize sedentary time in everyday life might need to suggest that more intense and frequent breaks are needed. View the abstract.


Exercise during Chemotherapy: When and How Hard?

Cancer chemotherapy side effects, like fatigue, pain and nausea, are typically intense immediately following an infusion and gradually subside until the next treatment two to three weeks later. Although exercise can lessen the side effects, the side effects often cause patients to avoid exercise. As such, researchers developed a “chemotherapy-periodized” exercise training program designed to work around chemotherapy‘s bad days. Breast cancer patients participated in cardiovascular (treadmill or bike) and strength exercises three days per week over 8-12 weeks of chemotherapy treatment. For one week after each infusion, cardiovascular exercise intensity was reduced and fewer strength exercises were performed. Although the patients’ fatigue was highest during treatment weeks, the weeks leading up to the next treatments resulted in lower fatigue, even while the exercise intensity and number of strength exercises were increased. The chemotherapy-periodized group also attended more of their exercise sessions than women whose exercise program did not change according to treatment schedule. This “chemotherapy-periodized” approach has the potential to improve quality of life and reduce treatment side effects by increasing the total number of days women will exercise while undergoing chemotherapy treatment. View the abstract.


Benefits of Exercise for African American Men at Risk for Diabetes

Although they have a higher-than-normal risk of developing diabetes, African American men have been underrepresented in studies designed to determine how much exercise is needed to reduce diabetes risk factors. In this study, 113 African American men with a family history of diabetes were divided into two groups for five months. One group completed 150 minutes of endurance activity and two days of strength training each week at local YMCA's in accordance with national guidelines. The other group did not exercise, but received information on preventing diabetes. Blood sugar and insulin levels changed similarly in both groups of men. However, men who exercised improved their fitness, lowered their waist size, reduced the amount of fat in their body, and were more efficient at lowering blood sugar levels (i.e., lowered blood sugar with less insulin production) compared to men who did not exercise. This novel study indicates that regular exercise can reduce some diabetes risk factors in African American men. Thus, it is important to identify ways to help African American men maintain habitual exercise. View the abstract.


Physical Activity and Academic Performance: Familial Background

Although physical activity may be associated with academic performance, whether or not physical activity actually causes academic performance is debatable. In this new study, investigators examined the longitudinal association between physical activity and academic performance to study the effect of familial background. Using a genetically informative twin study design, participants were followed from adolescence to young adulthood. The results suggest that the common genetic background and shared family environment are likely to explain the positive association between physical activity and academic performance. Thus, an intervention directly aimed at promoting physical activity to improve academic performance may not be effective. Rather, an intervention in a family environment is required for increasing both a child’s physical activity and academic performance. View the abstract.


Occupational Activities: Factors that Tip the Balance from Bone Accrual to Bone Loss

It is commonly assumed that bone mass increases with vigorous exercise; however, consistent repetitive bouts of excessive loading with exercise or occupational tasks can actually lead to bone loss, microcracks and stress fractures. Occupational-related physical activities usually provide no cardiovascular benefits and can increase the risk of bone loss or degeneration in hand/wrist bones, shoulders and lumbar vertebrae. To explore underlying reasons, a rat model of overuse injury was developed. Investigators using this model observed increased bone mass in forearm bones in response to prolonged moderate loading, in association with an increase in the number and activity of the cells responsible for producing bone matrix. In contrast, prolonged high-intensity loading induced a loss of bone mass and microcracks. Persistent inflammation in damaged tissues and insufficient time to recover from microdamage also contributed to net bone loss. Authors suggest avoiding prolonged excessive loading and increasing rest and recovery allowances to enhance tissue recovery. View the abstract.