From Christine Duffill
I find it hard to believe your assertion that running and walking at 6 kilometres an hour both burn the same number of calories, while dispelling myths about fat (15 November, p 32). My intuition forces me to think that there must be a difference in energy expenditure of two such different modes of locomotion. When running, the body is being propelled into the air against the force of gravity; when walking, one foot remains firmly on the ground at all times.
Southampton, Hampshire, UK
