I cut out the bulk of this article, but this info should help you out.
The Journal of Strength and Conditioning Research: Vol. 13, No. 4, pp. 412–421.
Time of Day Effect on Athletic Performance: An Update
THOMAS A. CAPPAERT*
Department of Sports Medicine, University of Charleston, Charleston, West Virginia 25304.
ABSTRACT
Various psychological and physiological functions have been shown to undergo changes relative to the time of the solar day. These variations are known as circadian or diurnal rhythms. These functions exhibit peaks and troughs of maximum and minimum function at specific times of the day. Many components related to athletic performance have been shown to possess these circadian rhythms. A literature search was performed using the databases Medline, SPORTDiscus, and the Cumulative Index to Nursing and Allied Health Literature. Keywords used in the search were “circadian rhythm and exercise” and “diurnal variations and exercise.” Articles were used if they were related to athletic performance and/or testing and were published after 1985. The articles were then separated into the broad subjects of time of day effects on acute responses to exercise, chronic responses to exercise, and effect of chronotype on exercise. The conclusions reached were that a probable time of day effect is present for the following conditions: isotonic and isokinetic strength measures, anaerobic power and capacity, and body temperature and exercise response. A more equivocal relationship was found between time of day and endurance training, ratings of perceived exertion, chronotype and exercise, arm exercise, and self-paced exercise.
Key Words: circadian rhythm, exercise, diurnal variations, exercise testing, body temperature
Introduction Return to TOC
The idea of a variation throughout the solar day of physiological and psychological variables is not recent. Daily variation in body temperature was first reported in 1778 (
15). These time-dependent variances are known as circadian rhythms. These psychophysiological functions exhibit maximum and minimum phases throughout the day. Many of these can have an effect on sports performance.
It is important, therefore, for coaches and athletes to be aware of how the time of day will affect various components of physical performance. The hallmark of a good training program is the identification and maximum improvement of the components necessary to excel at a particular athletic endeavor, be they physical or mental. If one of these components has a time of day variance, then it behooves the coach and/or athlete to schedule the activity at the time that the particular component will be at its maximum effectiveness. This has applications in planning training sessions, testing sessions, and competition times. Previous research (
20,
26,
29) has addressed the time of day effects on basic psychophysiological responses at rest and exercise. Many of these responses are related to athletic performance. Recent research has begun to study some of these basic responses as they relate to more specific aspects of physical/athletic performance.
The purposes of this article are to review the recent literature as it pertains to circadian rhythms in variables of athletic performance, to reach conclusions concerning this research, and to devise recommendations to apply these findings to practical athletic performance and testing.
Practical Applications
Based upon the results of previously reviewed investigations and of the studies reviewed in this article, a time of day effect on exercise is a factor that must be taken into account. This would have practical applications in planning training sessions, testing sessions, experimental investigations, and competitive events. Optimal performance is the paramount objective of athletic endeavor, and adjusting for time of day differences appears to be an important factor in attaining that optimal performance. Based upon this review, the following guidelines or recommendations can be set forth:
(a) Endurance training should probably be conducted at the same time of day that performance is scheduled. This effect seems independent of gender. The question of whether morning or afternoon endurance training is more beneficial is still unresolved. The answer would have implications for designing training programs to enhance aerobic capacity.
(b) When using RPEs to monitor exercise intensity above the ventilatory threshold, time of day should be considered in interpreting ratings. This factor would have implications when monitoring intensity during training or testing.
(c) Handgrip strength measured isotonically and knee flexion/extension measured isotonically or isokinetically should probably be performed in the afternoon. The earlier leg-strength peak of women should also be considered. When comparing separate isokinetic test results, the testing times should be within 30 minutes of one another. This factor would have the most impact during testing to attain baseline or progress measurements for an athlete.
(d) Performance of short-term, high-intensity exercise should probably be scheduled in the afternoon to realize maximum performance. This effect is independent of gender. This factor has implications for testing, the training of anaerobic components of fitness, and scheduling of competitions.
(e) “Morning” and “evening” types may need to be considered when using maximal exercise or measuring O2max. The use of the Horne-Ostberg questionnaire (
14) or the questionnaire suggested by Smith et al. (
27) can help to establish morning or evening preference, and then testing, workouts, training programs, or competitions can be scheduled accordingly.
(f) Limited evidence shows that maximal arm exercise probably should be performed in the afternoon to maximize performance. This may have implications for testing, training, and scheduling competitions.
(g) Increased body temperature during afternoon exercise should probably be accounted for when scheduling maximal exercise. This effect may limit performance because of increased thermoregulatory demand compared with morning exercise. This factor would have implications in the scheduling of testing, training, and competition, especially prolonged endurance events.
(h) Adequate warm-up should be performed before morning exercise to ensure proper physiological readiness for intense exercise. This factor will have implications for testing, training, and competitions.
(i) Training and competition should be scheduled at generally the same time of the day. If this is impractical, the athlete may be able to adjust the sleep/wake cycle so that the performance time will coincide with the adjusted peak times for a particular rhythm. This is in agreement with the recommendations of Winget et al. (
29).
(j) Peak times for certain performance variables are generally subject to individual differences and will need experimentation by the athlete to find the optimum performance time for these variables.
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