Timing and consistency of one's daily physical activity could be related with an improved cardiorespiratory fitness and walking efficiency -- two important aspects of healthy ageing, according to a study.

Circadian rhythms, or biological clocks, regulate a person's activities over a 24-hour period -- including sleep-wake cycles and wide-ranging physiological and metabolic functions.

"The circadian mechanisms that generate daily rhythms in our system are important for our well-being," senior author Karyn Esser, professor and chair at the University of Florida College of Medicine, US, said.