EIMD Mechanisms Causing Force Loss

Summary

We have hypothesized: 1) Caffeine will increase maximal voluntary strength compared to placebo in undamaged muscle. 2) Caffeine will increase muscle activation compared to placebo in undamaged muscle. 3) Caffeine will enhance spinal excitability (indicated by an enhanced H-reflex) compared to placebo in undamaged muscle. 4) Caffeine will raise the pressure-pain threshold (indicating decreased pain sensitivity) in the calf muscle compared to placebo in undamaged muscle. 5) Caffeine will reduce the amount of low-frequency fatigue, indicated by an enhanced 20-100 hertz strength ratio, compared to placebo in undamaged muscle. 6) Caffeine will increase maximal voluntary strength compared to placebo in damaged muscle. 7) Caffeine will increase muscle activation compared to placebo in damaged muscle. 8) Caffeine will enhance spinal excitability (indicated by an enhanced H-reflex) compared to placebo in damaged muscle. 9) Caffeine will raise the pressure-pain threshold (indicating decreased pain sensitivity) in the calf muscle compared to placebo in damaged muscle. 10) Caffeine will reduce the amount of low-frequency fatigue, indicated by an enhanced 20-100 hertz strength ratio, compared to placebo in damaged muscle. The proposed research will determine the effects of a 5mg/kg body weight dose of caffeine on muscular strength, activation, H-reflex function, and excitation-contraction coupling before and after exercise-induced muscle damage. The long term objectives are to gain a better understanding of caffeine and its affects following exercise-induced muscle damage allowing us to understand how caffeine is mechanistically interacting with functions of the body.

Timeline

Start

2014-08

Primary completion

2015-05

Completion

2015-05

Publications

• Background Ploutz-Snyder LL, Giamis EL, Formikell M, Rosenbaum AE. Resistance training reduces susceptibility to eccentric exercise-induced muscle dysfunction in older women. J Gerontol A Biol Sci Med Sci. 2001 Sep;56(9):B384-90. doi: 10.1093/gerona/56.9.b384.
• Results Clarkson PM, Sayers SP. Etiology of exercise-induced muscle damage. Can J Appl Physiol. 1999 Jun;24(3):234-48. doi: 10.1139/h99-020.
• Results Warren GL, Ingalls CP, Lowe DA, Armstrong RB. What mechanisms contribute to the strength loss that occurs during and in the recovery from skeletal muscle injury? J Orthop Sports Phys Ther. 2002 Feb;32(2):58-64. doi: 10.2519/jospt.2002.32.2.58.
• Results Allen DG. Eccentric muscle damage: mechanisms of early reduction of force. Acta Physiol Scand. 2001 Mar;171(3):311-9. doi: 10.1046/j.1365-201x.2001.00833.x.
• Results Balnave CD, Allen DG. Intracellular calcium and force in single mouse muscle fibres following repeated contractions with stretch. J Physiol. 1995 Oct 1;488 ( Pt 1)(Pt 1):25-36. doi: 10.1113/jphysiol.1995.sp020943.
• Results Balnave CD, Davey DF, Allen DG. Distribution of sarcomere length and intracellular calcium in mouse skeletal muscle following stretch-induced injury. J Physiol. 1997 Aug 1;502 ( Pt 3)(Pt 3):649-59. doi: 10.1111/j.1469-7793.1997.649bj.x.
• Results Meyers BM, Cafarelli E. Caffeine increases time to fatigue by maintaining force and not by altering firing rates during submaximal isometric contractions. J Appl Physiol (1985). 2005 Sep;99(3):1056-63. doi: 10.1152/japplphysiol.00937.2004. Epub 2005 May 5.
• Results Nosaka K, Newton M. Concentric or eccentric training effect on eccentric exercise-induced muscle damage. Med Sci Sports Exerc. 2002 Jan;34(1):63-9. doi: 10.1097/00005768-200201000-00011.

Drugs

Indications

No indication recorded.