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Diurnal differences in human muscle isometric force and rate of force development in vivo are associated with differential phosphorylation of sarcomeric M-band proteins.

Malik, Z, Bowden Davies, K, Hall, E, Barrett, J, Pullinger, S, Erskine, RM, Shepherd, SO, Iqbal, Z, Edwards, BJ and Burniston, JG (2020) Diurnal differences in human muscle isometric force and rate of force development in vivo are associated with differential phosphorylation of sarcomeric M-band proteins. Proteomes, 8 (3). ISSN 2227-7382

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The maximum force of skeletal muscle exhibits circadian variation that is associated with time-of-day differences in athletic performance. We investigated whether the diurnal difference in force is associated with the post-translational state of muscle proteins. Twenty physically active men (mean ± SD; age 26.0 ± 4.4 y, height 177.3 ± 6.8 cm, body mass 75.1 ± 8.2.8 kg) completed 5 familiarisation sessions where-in they practiced all maximal efforts. Thereafter they performed experimental sessions, in the morning (08:00 h) and evening (17:00 h), counterbalanced in order of administration and separated by at least 72 h. Rectal, skin, muscle temperatures and ratings of perceived effort measurements where made after the subjects had reclined for 30 min (rest) and after the 5-min cycle ergometry warm-ups and prior to the measurement of knee extensor maximal voluntary isometric contraction (MVIC; including twitch-interpolation) and peak rate of force development (RFD). Data handling: 10 subjects from the cohort of 20 volunteered for muscle biopsy procedures, hence only their data is reported for temperature, MVIC and RFD to align with proteomic analyses. Samples of vastus lateralis were collected immediately after exercise and were analysed by ‘top-down’ and ‘bottom-up’ proteomic methods. Rectal and muscle temperatures were higher at rest in the evening (mean difference of 0.51°C and 0.69°C; p<0.05) than in the morning. MVIC force in the evening was significantly greater than in the morning (mean difference of 67 N, 9.3%; p<0.05), similarly peak RFD (mean difference of 1080 N/s, 15.3%; p<0.05) was improved in the evening. 2D gel analysis encompassed 122 proteoforms and discovered 6 statistically significant (p<0.05; false discovery rate [FDR] = 10%) diurnal differences. Phosphopeptide analysis identified 1,693 phosphopeptides and detected 140 phosphopeptides from 104 proteins that were more phosphorylated (p<0.05, FDR=22%) in the morning vs. evening. Myomesin 2, muscle creatine kinase and the C-terminus of titin, exhibited the most robust (FDR<10%) diurnal differences. In summary, the effects of time of day where seen in measures of rectal and muscle temperature and muscle performance. Exercise in the morning, compared to the evening, coincided with greater phosphorylation of M-band-associated proteins in human muscle. These protein modifications may alter M-band structure and disrupt force transmission, thus potentially explaining the lower force output in the morning.

Item Type: Article
Uncontrolled Keywords: 06 Biological Sciences, 11 Medical and Health Sciences
Subjects: R Medicine > RC Internal medicine > RC1200 Sports Medicine
Divisions: Sport & Exercise Sciences
Publisher: MDPI
Date Deposited: 03 Sep 2020 12:01
Last Modified: 04 Sep 2021 07:18
DOI or ID number: 10.3390/proteomes8030022
URI: https://researchonline.ljmu.ac.uk/id/eprint/12919
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