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Student Editorials

Exercise for good health

BMJ 2004; 329 doi: (Published 01 July 2004) Cite this as: BMJ 2004;329:0407266
  1. Tiago Villanueva, Clegg scholar BMJ and intercalating medical student1,
  2. Karim Khan, North American editor2
  1. 1University of Lisbon
  2. 2British Journal of Sports Medicine, BMJ Publishing Group

Physical activity is essential for maintaining good health. But it can also do more harm than good. Tiago Villanueva and Karim Khan explain

For the hunter-gatherer society, daily physical activity was a prerequisite for survival.w1 Activities such as hunting, tool making, butchering and other food preparation, preparing clothing, carrying firewood and water, and moving to new campsites all needed physical labour.

Nowadays, as most modern societies have predominantly sedentary jobs, people spend about 38% of the caloric expenditure per unit body mass compared with late paleolithic stone agers. We tend to be physically active for recreational purposes and to get fit or maintain their fitness.1 Regular physical activity leads to numerous health improving effects. But just how much physical activity is necessary to achieve the benefits, and can exercising too much do harm?


Physical activity, exercise, and sport are not quite the same thing. Physical activity is an umbrella term meaning any bodily movement produced by skeletal muscles that results in expenditure of energy above the basal level (includes work and leisure).2 Examples include walking, cycling, housework, cleaning the house, and climbing the stairs. Exercise is a subcategory of physical activity that is planned, structured, repetitive and purposive in the sense that improvement of or maintenance of one or more components of physical fitness is the objective.w2 Examples include brisk walking, aerobic dancing, and some active hobbies, such as gardening. Sport is physical activity in structured competitive situations governed by rules.3

Benefits of physical activity

Because the human genome has not changed …

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