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Longevity has been noted to increase in the elderly population in developed countries(1). Although ageing negatively affects many aspects of physical performance, the underlaying mechanisms remain unclear(2). Thus, this limited knowledge has hampered the development of a proper approach to support age-related issues. Physical performance, including muscle strength, balance and agility, are fundamental elements of activity of daily living that play a pivotal role in supporting an active and comfortable lifestyle throughout the stages of life. Ageing deteriorates not only the physical performance, but also an individual's eating ability(3), and considering the close relationship between these two important functions, it has been suggested that the diet plays an essential role in supporting physical performance especially in ageing individuals.
Ageing is a complex phenomenon affecting various organ systems including the neuromuscular system(4-6), where changes in the neuromuscular components of aged animals have been previously shown to negatively affect both the quality and quantity of physical performance(7). The neuromuscular system is a unique structure containing two independent tissues comprising a skeletal muscle and a peripheral nerve(8). The synaptic structure of this particular system - termed neuromuscular junctions - plays a critical role in various functions that are essential for active daily living and presents as a possible target for impairment of physical activity by ageing.
Previous studies have assessed the effects of several nutritional components possessing different functions on improving the physical activity of relatively healthy elderly individuals in both mice and man(9-11). Recently, our group identified that the administration of milk fat globule membrane (MFGM) mediated a unique and preferable effect on improving the physical performance in mice(10-13)and human subjects(14-17), which suggests an improvement in muscle mass and strength through the improved functions of neuromuscular junctions in aged individuals with regular exercise. MFGM secreted by the epithelial cells lining the alveolar lumen of the lactating mammary gland contains various enzymes, proteins and lipids, including sphingomyelin(15,18,19)