Age, exercise and fatigue

ASK A SCIENTIST

Every time my three young grandchildren come to visit for a few hours, I’m exhausted for a day or more afterwards. But they have as much energy as ever next morning. Is this about their adrenaline, or metabolism, or just my own aging, or what?

Stephen Chalcroft, a geriatrician at the University of Otago, responded:

Although young children have limited cardiovascular activity and inefficient exercise strategies, which result in them tiring rapidly, it is thought that they also have relatively fatigueresistant muscles with the ability to recover quickly after exercise. Comparisons with untrained adults have demonstrated that children outperformed in that they used more of their aerobic metabolism and were less tired during the highintensity physical activities.

Older adults may maintain quite high levels of physical activity and endurance in later years. However, there are factors that can increase vulnerability to fatigue as we age: circadian patterns of sleep and wakefulness may change with shortened sleep cycles and less restorative sleep occurring; muscle mass declines with age, and with that our muscle strength decreases and fatigability increases. Exercise and training can compensate for some of these changes. Mental energy and cognitive reserve may decline with age in some individuals. Lifestyle changes may also impact. Those who become a caregiver and also try to fit in household responsibilities, work, etc may find it hard to have a ‘‘recovery period’’ during the day. Worse, if they provide night care, health issues impact upon function. In older adults there are more chronic illnesses and medications.

Other contributions to increased fatigue include: medications that sedate, or affect muscle function (alcohol and recreational drugs should be included here); disturbed sleep patterns (e.g., obstructive sleep apnoea); anaemia; arthritis; chronic fatigue syndrome; and many serious diseases, including cardiac disease, cancer, thyroid disorders, Parkinsonism, and depression.