ABSTRACT
While it is acknowledged that the term “ageing” broadly incorporates changes across the entire lifespan – including those that occur during
development – we will restrict the use of the term here to mean senescence. Due to improvements in nutrition and medicine, the life expectancy for people in many countries has increased markedly in the past century. As a result, the average age of our population is increasing, bringing with it a critical need for understanding the basic biology of ageing and its effects on various physiological systems. With this knowledge, effective approaches for encouraging healthy ageing can be developed. Fatigue can mean many things, particularly in older adults. For example, fatigue can be characterised as the lassitude or sense of exhaustion that develops over the course of a day. Muscle fatigue is a type of fatigue that is both quantifiable and relevant to adequate physical functioning. A further distinction can be made between muscle fatigue (the decline in maximal force-producing capability during contractions) and muscle endurance (the time for which target force can be maintained). Studies of human skeletal muscle fatigue or endurance typically involve a single muscle group. As a result, the effects of systemic changes, such as the ability of the cardiovascular system to provide adequate blood flow and oxygen to the working tissue, are minimised. While this approach presents something of a constraint in terms of understanding the factors that limit vigorous whole-body activity, it does allow the contributions of age-related changes in neuromuscular function to be clarified in the absence of confounding influences.
