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The effects of circadian rhythmicity of salivary cortisol and testosterone on maximal isometric force, maximal dynamic force, and power output

Teo, Wei-Peng, McGuigan, Michael R. and Newton, Michael J. 2011, The effects of circadian rhythmicity of salivary cortisol and testosterone on maximal isometric force, maximal dynamic force, and power output, Journal of strength and conditioning research, vol. 25, no. 6, pp. 1538-1545, doi: 10.1519/JSC.0b013e3181da77b0.

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Title The effects of circadian rhythmicity of salivary cortisol and testosterone on maximal isometric force, maximal dynamic force, and power output
Author(s) Teo, Wei-PengORCID iD for Teo, Wei-Peng orcid.org/0000-0003-3929-9778
McGuigan, Michael R.
Newton, Michael J.
Journal name Journal of strength and conditioning research
Volume number 25
Issue number 6
Start page 1538
End page 1545
Total pages 8
Publisher Lippincott, Williams & Wilkins
Place of publication Philladelphia, Pa.
Publication date 2011-06
ISSN 1533-4287
Keyword(s) Science & Technology
Life Sciences & Biomedicine
Sport Sciences
time of day
isometric midthigh pull
aural temperature
session rating-of-perceived exertion
HEALTHY-YOUNG MEN
MORNINGNESS-EVENINGNESS
INDIVIDUAL-DIFFERENCES
MUSCULAR PERFORMANCE
DIURNAL-VARIATION
LEG EXTENSORS
WARM-UP
STRENGTH
TIME
TEMPERATURE
Summary The study investigated the effects of circadian rhythm of cortisol (C) and testosterone (T) on maximal force production (Fpeak) and power output (Ppeak). Twenty male university students (mean age = 23.8 ± 3.6 years, height = 177.5 ± 6.4 cm, weight = 78.9 ± 11.2 kg) performed 4 time-of-day testing sessions consisting of countermovement jumps (CMJs), squat jumps (SJ), isometric midthigh pulls (IMTPs), and a 1-repetition maximum (1RM) squat. Saliva samples were collected at 0800, 1200, 1600, and 2000 hours to assess T and C levels on each testing day. Session rate-of-perceived exertion (RPE) scores were collected after each session. The results showed that Fpeak and Ppeak presented a clear circadian rhythm in CMJ and IMTP but not in SJ. One repetition maximum squat did not display a clear circadian rhythm. Session RPE scores collected at 0800 and 2000 hours were significantly (p ≤ 0.05) higher than those obtained at 1200 and 1600 hours. Salivary T and C displayed a clear circadian rhythm with highest values at 0800 hours and lowest at 2000 hours; however, no significant correlation was found between T and C with Fpeak and Ppeak. A very strong correlation was found between Taural with Fpeak of CMJ and IMTP and Ppeak of CMJ (r = 0.86, r = 0.84 and r = 0.8, p ≤ 0.001). The study showed the existence of a circadian rhythm in Fpeak and Ppeak in CMJ and IMTP. The evidence suggests that strength and power training or testing should be scheduled later during the day. The use of Taural seemed to be a more effective indicator of physical performance than hormonal measures, and the use of session RPE should also be closely monitored because it may present a circadian rhythm.
Language eng
DOI 10.1519/JSC.0b013e3181da77b0
Field of Research 1106 Human Movement And Sports Science
110699 Human Movement and Sports Science not elsewhere classified
Socio Economic Objective 929999 Health not elsewhere classified
HERDC Research category C1.1 Refereed article in a scholarly journal
ERA Research output type C Journal article
Copyright notice ©2011, Lippincott, Williams & Wilkins
Persistent URL http://hdl.handle.net/10536/DRO/DU:30077370

Document type: Journal Article
Collection: School of Exercise and Nutrition Sciences
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