Effect of Time‐of‐Day‐Specific Strength Training on Serum Hormone Concentrations and Isometric Strength in Men

Abstract

A time-of-day influence on the neuromuscular response to strength training has been previously reported. However, no scientific study has examined the influence of the time of day when strength training is performed on hormonal adaptations. Therefore, the primary purpose of this study was to examine the effects of time-of-day-specific strength training on resting serum concentrations and diurnal patterns of testosterone (T) and cortisol (CORT) as well as maximum isometric strength of knee extensors. Thirty eight diurnally active healthy, previously untrained men (age 20-45 yrs) underwent a ten-week preparatory strength training period when sessions were conducted between 17:00-19:00 h. Thereafter, these subjects were randomized into either a morning (n=20, training times 07:00-09:00 h) or afternoon (n=18, 7:00-19:00 h) training group for another ten-week period of time-of-day-specific training (TST). Isometric unilateral knee extension peak torque (MVC) was measured at 07:00, 12:00, 17:00, and 20:30 h over two consecutive days (Day 1 & Day 2) before and after TST. Blood samples were obtained before each clock-time measurement to assess resting serum T and CORT concentrations. A matched control group (n=11) did not train but participated in the tests. Serum T and CORT concentrations significantly declined from 07:00 to 20:30 h on all test days (Time effect, p<.001). Serum CORT at 07:00 h was significantly higher on Day 1 than Day 2 in the control and afternoon group, both in Pre and Post conditions (Day x Time interaction, p<.01). In the morning group, a similar day-to-day difference was present in the Pre but not Post conditions (Time x Group interaction, p<.05). MVC significantly increased after TST in both the morning and afternoon groups (Pre to Post effect, p<.001). In both groups, a typical diurnal variation in MVC (Time effect, p<.001) was found, especially on Day 2 in the Pre condition, and this feature persisted from Pre to Post in the afternoon group. In the morning group, however, diurnal variation was reduced after TST on both Day 1 and Day 2 (Pre to PostxDay x TimexGroup interaction, p<.05). In conclusion, 10 weeks of morning time-of-day-specific strength training resulted in reduced morning resting CORT concentrations, presumably as a result of decreased masking effects of anticipatory psychological stress prior to the morning testing. The typical diurnal pattern of maximum isometric strength was blunted by the TST period in the morning but not the afternoon group. However, the TST period had no significant effect on the resting total T concentration and its diurnal pattern and on the absolute increase in maximum strength.

Circadian Cycle and Its Influence on Parameters of Aerobic Training

“…The literature suggests that the best moments of peak performance are related to body temperature [15] with a worse performance in the morning and a better outcome in the afternoon / evening [16]. In our study we found a 2% increase in body temperature, which leads us to think that this increased tendency to perform better during the night can be directly related to the increase in body temperature, in corroborates with other studies which indicate values larger afternoon / evening [16,17,18].…”

“…In our study we found a 2% increase in body temperature, which leads us to think that this increased tendency to perform better during the night can be directly related to the increase in body temperature, in corroborates with other studies which indicate values larger afternoon / evening [16,17,18].…”

Time of Day Effect on Soccer—Specific Field Tests in Tunisian Boy Players

“…Usually, peak performances were found to occur in the early evening and correspond to the maximum body (Aloui et al, 2012;Reilly et al, 2007, Bernard et al, 1998Melhim et al, 1993;Souissi et al, 2010). Although the exact mechanisms explaining this relationship remain unclear, it has been suggested that the increase in body temperature allows an increase in energy metabolism, improved muscle compliance, facilitate actin-myosin crossbridging (Weipeng et al, 2011), enhance metabolic reactions, increase the extensibility of connective tissue, reduce muscle viscosity and increase conduction velocity of action potentials (Sedliak et al, 2007). Even though it is still largely accepted that temperature is the primary circadian indicator of physical performance, recent evidence has challenged the traditional views about the relationship between body temperature and exercise performance.…”

Resistance exercise with whey protein ingestion affects mTOR signaling pathway and myostatin in men

“…However, RT itself decreased Akt phosphorylation. The control group results ensured that the results were not due to repeated biopsy, diurnal rhythm, or time of year (47,57).…”

“…1). A control group was included, and all the measurements were always carried out at the same time of day to exclude the effects of biopsy sampling or effects of time of year or daily variations (47,57). All the measurements were preceded by at least 2 days of rest from physical activity.…”