Maybe Later
If your older maybe later in day, most of similar studies with other ages say same thing that I have heard about. I always though 1-2 pm was the best time for me ever and this is when I worked second shift.
J Appl Physiol 92: 2319-2325, 2002. First published February 1, 2002; doi:10.1152/japplphysiol.01116.2001
Vol. 92, Issue 6, 2319-2325, June 2002
Aged men display blunted biorhythmic variation of muscle performance and physiological responses
Michael R. Deschenes, Laurie L. Bronson, Meredith P. Cadorette, Julia E. Powers, and John C. Weinlein
Department of Kinesiology, The College of William and Mary, Williamsburg, Virginia 23187-8795
Aging is known to disrupt the "biological clock" that governs physiological variables at rest. This study sought to determine whether aged men demonstrated biorhythmic variation in muscle performance during resistance exercise and physiological responses to that stimulus. Ten aged (75.6 ± 1.6 yr; mean ± SE) men completed an isokinetic testing protocol of knee extensors and flexors at 0800, 1200, 1600, and 2000 h. Although time of day variation in peak torque was detectable, significant (P 0.05) oscillation was established only in the knee flexors at 3.14 rad/s. Heart rate, blood pressure, and rectal temperature displayed no significant variation, but trends (P < 0.10) in oscillation of postexercise blood pressure and rectal temperature were noted. Temporal patterns in biorhythmic variation of muscle performance, as well as thermal and cardiovascular measures, emulated those observed in a previous study involving young men where the magnitude of variation was sufficient to achieve statistical significance. Similar to our earlier findings in young men, however, pre- and postexercise testosterone and cortisol concentrations demonstrated significant variation among aged men. These data confirm the blunting of biorhythmic variation in muscle performance and physiological variables, except for circulating hormones, in aged men.
In summary, the data generated by this investigation confirmed our initial hypothesis. We have determined that, among aged men, muscle function and selected physiological variables display muted biorhythmic variation that in temporal pattern, but not in magnitude, emulates biorhythmic variation noted in young men. From a mechanistic standpoint, our findings suggest that modifications in target tissue rather than in the biological clock itself are primarily responsible for this attenuation of biorhythmicity, at least during the segment of the day studied. From an applied standpoint, the data reported here indicate that older men may perform resistance exercise at any time of day between the hours of 0800 and 2000, with expectations of roughly equivalent performance and stress imparted to the cardiovascular and thermoregulatory systems. Hormonal data, however, reveal that a more favorable anabolic environment exists in the early evening hours and that testosterone levels are most responsive to resistance exercise during those same hours.