“…Recently, a large focus of the field of exercise physiology has been on the effect of time-of-day on exercise capacity and athletic performance. On the whole, measures of both strength and endurance performance tend to be lower in early morning and higher in the afternoon/evening (Atkinson and Reilly, 1996; Atkinson and Speirs, 1998; Baxter and Reilly, 1983; Bessot et al, 2006; Czelusniak et al, 2021; Douglas et al, 2021; Edwards et al, 2005; Martin et al, 1999; Reilly et al, 2007; Reilly and Down, 1986; Rodahl et al, 1976). While a number of factors have been proposed to underlie these performance impacting effects of time-of-day, including body temperature (Bergh and Ekblom, 1979; Harrison and Bers, 1989), motor unit recruitment (Gueldich et al, 2017; Nicolas et al, 2007; Sedliak et al, 2008), and meal timing/muscle glycogen status (Kerksick et al, 2017; Koch et al, 2020), an emphasized point in the field is that variation in exercise performance is due to circadian fluctuations in the intrinsic properties of skeletal muscle (Douglas et al, 2021).…”