Scanning Sports Medicine
PHYSICAL ACTIVITY PATTERNS DURING PREGNANCY
In Medicine & Science in Sport & Exercise ® 2008, Volume 40, Number 11, the authors of this study set out to define the mode, frequency, duration, and intensity of physical activity among pregnant women. Unlike most studies that only report physical activity for recreational and overall activity, this study included physical activity related to occupation, caregiving, and household activity. Additionally, the authors explored whether these women reached the recommended levels of activity and how their patterns changed during pregnancy. Data were collected during the third phase of the Pregnancy, Infection, and Nutrition Study (PIN3) that investigated 1482 pregnant women, where the authors used telephone interviews to determine recall of the past week's physical activity at both 17-22 and 27-30 wk. The study found that the overall physical activity level decreased during pregnancy, particularly in caregiving, outdoor household, and recreational activity. Women who were active during their second and third trimesters were higher across all modes of activity than those who became active or inactive during pregnancy. The majority of the women did not reach the recommended physical activity levels even when combining the U.S. Centers for Disease Control & Prevention and the American College of Sports Medicine's exercise guidelines to allow for a broader definition of physical activity than the traditional American College of Obstetricians and Gynecologists guidelines used in most pregnancy studies. Prevalence rates varied from 3%-38% within the group. Bottom line: This study provides important information to physicians about what types of physical activity pregnant women are partaking in and also should prompt further research on modes of activity in the postpartum period.
RELATIONSHIP BETWEEN SUB-DOMAINS OF TOTAL PHYSICAL ACTIVITY AND MORTALITY
Another article in Medicine & Science in Sport & Exercise ®, 2008, Volume 40, Number 11, looked at the mode of physical activity and its impact upon all-cause and cardiovascular mortality. While strong epidemiologic evidence exists for an inverse relationship between physical activity and mortality risk, it is unclear how the association varies based upon the domain of life in which activity takes place. Through the use of an English-population based cohort of 14,903 participants with a mean age of 63, total and domain-specific physical activity was assessed using the validated questionnaire (EPAQ2). The EPAQ2 collected data on physical activity in four different domains: in and at home, work-related, commuting, and recreational. Engaging in sport exercise and intense physical activity at home were associated independently with all-cause mortality risk reductions of 19% and 34% respectively. An inverse association between cardiovascular mortality and physical activity at home or during exercise also was demonstrated. Work and transportation activity did not confer risk reductions. Bottom line: This study provides evidence of the health benefits that exist for physical activity at home and for exercise and may help to develop public health messages and programs for the aging population with regards to physical activity.
NHLH2: A BASIC HELIX-LOOP-HELIX TRANSCRIPTION FACTOR CONTROLLING PHYSICAL ACTIVITY
In Exercise and Sport Sciences Reviews, 2008, Volume 36, Number 4, the authors pro pose the hypothesis that transcriptional activity by Nhlh2 (NHLH2 in humans) controls either the ability or the motivation for exercise, based upon studies in mice that demonstrate that targeted deletion of Nhlh2 leads to adult-onset obesity and reduced physical activity. The article looks at various studies that support this hypothesis. The Human Obesity Gene Map lists numerous genes with mutant forms that contribute to inheritance of obesity, while others are candidates for linkage to human obesity phenotypes. The most recent update of the Human Gene Map for Performance and Health-Related Fitness Phenotypes lists 165 possible loci that have potential to modulate physical activity. These findings provide evidence for the existence of genes that can control either the motivation or ability to exercise. More than one third of the genes or loci that affect physical activity also are implicated in body weight regulation. NHLH2 also is implicated in the transcriptional control of melanocortin 4-receptor (MCHR). Functional polymorphisms in the MC4R gene are one of the most common causes of genetic obesity. Data also suggest that MC4R signaling may affect exercise behavior in humans and that NHLH2 transcriptionally can control levels of MC4R mRNA. Bottom line: Research continues to surface that supports the fact that there is a genetic component to obesity and inactivity.