For older adults, WALKING DOWNHILL increases risk of falls later

used to eccentric exercise. Ten participants were assigned to a level walking group, while nine were assigned to a downhill walking group. We matched participants by sex, age, physical activity levels and self-selected walking speed.

Participants attended our lab three days in a row. On the first day, we measured pre-exercise balance, muscle strength and physical functional performance. The participants then performed 30 minutes of either walking on a level treadmill or a downhill treadmill. We then measured the same outcomes immediately post-exercise, and again at 15 minutes, 30 minutes, 24- and 48-hour intervals after the initial exercise tests. All tests were undertaken at the same time of day.

As expected, we found that level walking caused a short-term increase in the risk of falling immediately after exercise. We found that 30 minutes of level walking caused a loss of balance, reduced physical function (such as being less able to stand from a chair and slower walking speed), and muscle weakness.

The increased risk of a fall immediately after concentric muscle contractions is probably because of the buildup of metabolic byproducts (such as hydrogen ions or inorganic phosphate) that reduce the muscle fibres’ ability to produce force. However, the negative effects of fatigue from this type of exercise were short lived. All participants recovered to pre-exercise levels around 30 minutes after stopping exercise.

In contrast, there was a delayed and prolonged increase in the risk of a fall following downhill walking. We were surprised to initially find no change in balance and physical function 30 minutes after exercise, though participants experienced muscle weakness. However, people had substantial losses of balance, physical function, and muscle weakness that occurred at least 24 hours after exercise – and remained impaired at least 48 hours after exercise.

These findings suggest that the muscle damage that happens after unaccustomed eccentric exercise leads to muscle weakness, balance problems, and impaired physical function – which can persist for several days.

This could endanger an older person’s safety by increasing their risk of falling.