How does fatigue contribute to fall risk and which functional test can help assess fatigue-related impairment?

• A. Fatigue enhances alertness; assess with rapid pace walking test.
• B. Fatigue has no impact on falls; assess with grip strength.
• C. Fatigue reduces strength and balance; assess with Timed Up and Go (TUG) test.
• D. Fatigue only affects mood; assess with PHQ-9.

Answer: (C)

Fatigue reduces the body’s capacity for sustained effort, which can weaken strength, impair balance, and slow reaction time. In older adults, this combination makes it harder to rise from a chair, stabilize during gait, and recover from perturbations, all of which raise the risk of a fall when tired. The Timed Up and Go test directly assesses these functional components by timing how long it takes to stand up from a chair, walk a short distance, turn around, walk back, and sit down. This task taps into lower-body strength, balance, gait speed, and coordination—areas that fatigue tends to deteriorate—so a longer time indicates fatigue-related impairment and greater fall risk.

Other options don’t fit as well because: a rapid pace walking test mainly measures brisk gait speed and may reflect aerobic capacity but not the integrated fatigue-related decline in strength, balance, and turning; grip strength assesses upper-extremity force and isn’t a primary predictor of falls due to fatigue; and the PHQ-9 screens mood and depressive symptoms, which can be related to fatigue but doesn’t measure how fatigue impairs functional mobility relevant to falls.