Repetitive strain injury (RSI), a “new” clinical syndrome, is characterized chiefly by a severe pain in wrists, forearms, hands and fingers. Although to date, the cause and pathogenesis of RSI is obscure, it is clearly related to frequent physical stresses; it seems to involve, mainly, musculoskeletal structures.

In 12 RSI subjects fluoride (F-) levels in bone were appreciably higher than 12 appropriate controls. Estimates of dietary intake of RSI subjects, revealed a Mg2+ deficit and an excessive F_ intake. Fluorotic bone has an increased Mg2+ content possibly due to some deposition of MgF2. The amorphous phase in bone may act as a “reservoir” of ions available to regulate plasma Ca, PO4 and Mg2+ levels. Fluoride accumulates in bone with age, especially in areas of active ossification. A locally raised F concentration in an osteocyte lacunae (during resorption) could interfere with normal functioning of the cell, or trigger the precipitation of crystalline apatite, or lead to the formation of MgF2. Any one of these reactions might interfere with the passage of Mg 2+ ions from the bone “reservoir” into circulating extracellular fluid. A localized Mg2+ deficiency could disturb pyrophosphate metabolism and lead to deposition of Ca salts in sensitive areas.

Through adjustment of dietary intake of the previously mentioned 12 RSI subjects which included more Mg2+ and less F-, eight of the subjects experienced marked relief from previously painful RSI symptoms after a six week test period.

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