| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Copenhagen Muscle Research Centre, August Krogh Institute, University of Copenhagen, Denmark. JBangsbo@aki.ku.dk
1. The aim of this study was to examine the effect of muscle pH on muscle metabolism and development of fatigue during intense exercise. 2. Seven subjects performed intense exhaustive leg exercise on two occasions: with and without preceding intense intermittent arm exercise leading to high or moderate (control) blood lactate concentrations (HL and C, respectively). Prior to and immediately after each exercise bout, a muscle biopsy was taken from m. vastus lateralis of the active leg. Leg blood flow was measured and femoral arterial and venous blood samples were collected before and frequently during the exhaustive exercises. 3. The duration of the exercise was shorter in HL than in C (3.46 +/- 0.28 vs. 4.67 +/- 0.55 min; means +/- S.E.M.; P < 0.05). Before exercise muscle pH was the same in C and HL (7.17 vs. 7.10), but at the end of exercise muscle pH was lower in HL than in C (6.82 vs. 6.65; P < 0.05). The release of potassium during exercise was higher (P < 0.05) in HL compared with C, but the arterial and femoral venous plasma potassium concentrations were the same at exhaustion in HL and C. 4. Muscle lactate concentration was higher in HL compared with C (3.7 +/- 0.4 vs. 1.6 +/- 0.2 mmol (kg wet weight)-1; P < 0.05), but the same at exhaustion (26.5 +/- 2.7 vs. 25.4 +/- 2.4 mmol (kg wet weight)-1). Total release of lactate in HL was lower than in C (18.7 +/- 4.5 vs. 50.4 +/- 11.0 mmol; P < 0.05), but rate of lactate production was not different (9.0 +/- 1.0 vs. 10.2 +/- 1.3 mmol (kg wet weight)-1 min-1). The rate of muscle glycogen breakdown was the same in C and HL (8.1 +/- 1.2 vs. 8.2 +/- 1.0 mmol (kg wet weight)-1 min-1). 5. The present data suggest that elevated muscle acidity does not reduce muscle glycogenolysis/glycolysis and is not the only cause of fatigue during intense exercise in man. Instead, accumulation of potassium in muscle interstitium may be an important factor in the development of fatigue.
This article has been cited by other articles:
|
|
 |
|
  A. R. Light, R. W. Hughen, J. Zhang, J. Rainier, Z. Liu, and J. Lee Dorsal Root Ganglion Neurons Innervating Skeletal Muscle Respond to Physiological Combinations of Protons, ATP, and Lactate Mediated by ASIC, P2X, and TRPV1 J Neurophysiol, September 1, 2008; 100(3): 1184 - 1201. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 A. M. Jones, D. P. Wilkerson, F. DiMenna, J. Fulford, and D. C. Poole Muscle metabolic responses to exercise above and below the "critical power" assessed using 31P-MRS Am J Physiol Regulatory Integrative Comp Physiol, February 1, 2008; 294(2): R585 - R593. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. G. Allen, G. D. Lamb, and H. Westerblad Skeletal Muscle Fatigue: Cellular Mechanisms Physiol Rev, January 1, 2008; 88(1): 287 - 332. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Broch-Lips, K. Overgaard, H. A. Praetorius, and O. B. Nielsen Effects of extracellular HCO3 on fatigue, pHi, and K+ efflux in rat skeletal muscles J Appl Physiol, August 1, 2007; 103(2): 494 - 503. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Mohr, P. Krustrup, J. J. Nielsen, L. Nybo, M. K. Rasmussen, C. Juel, and J. Bangsbo Effect of two different intense training regimens on skeletal muscle ion transport proteins and fatigue development Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2007; 292(4): R1594 - R1602. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. J. Nielsen, M. Mohr, C. Klarskov, M. Kristensen, P. Krustrup, C. Juel, and J. Bangsbo Effects of high-intensity intermittent training on potassium kinetics and performance in human skeletal muscle J. Physiol., February 1, 2004; 554(3): 857 - 870. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
