Purpose of review: To discuss the current data that acute periods of physical inactivity are harmful to health.
Recent findings: Bed rest prescribed for recovery from clinical conditions causes changes in thousands of mRNAs in leg muscles within days. Humans genetically more susceptible to metabolic disorders (low birth weight babies and type 2 diabetic offspring) are as, or more, susceptible to further metabolic dysfunction by the environmental perturbation of bed rest, as compared with healthy controls without these risk factors. High daily accumulations of sitting are not only associated with enhanced metabolic risk, but current findings report that increased sitting time leads to a reduction in insulin sensitivity. Reductions in walking or in ambulatory activity (lower step numbers taken by healthy humans) reduce insulin sensitivity and insulin signaling through Akt in skeletal muscle.
Summary: New findings using human models of physical inactivity (bed rest, increased sitting time, and reduced daily ambulatory activity), extend pre-existing research showing that transitioning to physical inactivity rapidly reduced metabolic health. Modern technological advances that remove standing, walking, and major limb movement initiate metabolic dysfunctions that likely play a fundamental role in the development of obesity and type 2 diabetes.
aHarry S Truman Memorial VA Hospital, USA
bDepartment of Nutrition and Exercise Physiology, USA
cDivision of Gastroenterology and Hepatology, Department of Internal Medicine, USA
dDepartment of Biomedical Sciences, USA
eDepartment of Medical Pharmacology and Physiology, USA
fDalton Cardiovascular Research Center, USA
gHealthy Activity Center, University of Missouri, Columbia, Missouri, USA
Correspondence to John P. Thyfault, PhD, Assistant Professor and Health Scientist, Harry S. Truman Memorial VA Hospital, Division of Gastroenterology and Hepatology, Departments of Nutrition and Exercise Physiology and Internal Medicine, University of Missouri, Columbia, MO 65201, USA Tel: +1 573 882 9818; fax: +1 573 882 0185; e-mail: firstname.lastname@example.org