Influence of chronotype on responses to a standardized, self-paced walking task in the morning vs afternoon : a pilot study

The response to sub-maximal physical activity performed in the morning and late afternoon by individuals with different chronotypes was investigated. 22 participants filled out the Morningness-Eveningness Questionnaire and underwent a self-paced walking task that consisted of walking from the top to the bottom of a hill and back three times (1,836 meters, with a slope of 14.16%). The task was repeated twice: late afternoon (16:30) and early morning (08:30). Walking speed (time for completion in seconds), heart rate, and perceived exertion were measured during each task, with overall results given as a general descriptive analysis. Preliminary findings suggest that chronotype is likely to influence the responses to exercise, mostly with evening-types seeming at a disadvantage when performing a physical task in the morning. Individuals can be classified by circadian typology or chronotype, which is the propensity to be a morning-type, evening-type, or neither-type. The circadian typology, commonly referred to as being a morning person or an evening person or somewhere in between, is involved not only in the expression of physiological rhythms, but also in habits and lifestyles, such as sleeping patterns (Park, Matsumoto, Seo, & Shinkoda, 1999) that emerge especially during adolescence (Park, Matsumoto, Seo, Kang, & Nagashima, 2002) and remain throughout adult life (Koukkari & Sothern, 2006).