The influence of respiratory acid-base changes on muscle performance and excitability of the sarcolemma during strenuous intermittent hand grip exercise

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Authors

  • M. Hilbert
  • V. Shushakov
  • N. Maassen

External Research Organisations

  • Hannover Medical School (MHH)
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Details

Original languageEnglish
Pages (from-to)571-579
Number of pages9
JournalJournal of Applied Physiology
Volume112
Issue number4
Publication statusPublished - Feb 2012
Externally publishedYes

Abstract

Acidification has been reported to provide protective effects on force production in vitro. Thus, in this study, we tested if respiratory acid-base changes influence muscle function and excitability in vivo. Nine subjects performed strenuous, intermittent hand grip exercises (10 cycles of 15 s of work/45 s of rest) under respiratory acidosis by CO 2 rebreathing, alkalosis by hyperventilation, or control. The PCO 2, pH, K + concentration ([K +]), and Na + concentration were measured in venous and arterialized blood. Compound action potentials (M-wave) were elicited to examine the excitability of the sarcolemma. The surface electromyogram (EMG) was recorded to estimate the central drive to the muscle. The lowest venous pH during the exercise period was 7.24 ± 0.03 in controls, 7.31 ± 0.05 with alkalosis, and 7.17 ± 0.04 with acidosis (P < 0.001). The venous [K +] rose to similar maximum values in all conditions (6.2 ± 0.8 mmol/l). The acidification reduced the decline in contraction speed (P < 0.001) but decreased the M-wave area to 73.4 ± 19.8% (P < 0.001) of the initial value. After the first exercise cycle, the M-wave area was smaller with acidosis than with alkalosis, and, after the second cycle, it was smaller with acidosis than with the control condition (P < 0.001). The duration of the M-wave was not affected. Acidification diminished the reduction in performance, although the M-wave area during exercise was decreased. Respiratory alkalosis stabilized the M-wave area without influencing performance. Thus, we did not find a direct link between performance and alteration of excitability of the sarcolemma due to changes in pH in vivo.

Keywords

    Exercise, Human

ASJC Scopus subject areas

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The influence of respiratory acid-base changes on muscle performance and excitability of the sarcolemma during strenuous intermittent hand grip exercise. / Hilbert, M.; Shushakov, V.; Maassen, N.
In: Journal of Applied Physiology, Vol. 112, No. 4, 02.2012, p. 571-579.

Research output: Contribution to journalArticleResearchpeer review

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abstract = "Acidification has been reported to provide protective effects on force production in vitro. Thus, in this study, we tested if respiratory acid-base changes influence muscle function and excitability in vivo. Nine subjects performed strenuous, intermittent hand grip exercises (10 cycles of 15 s of work/45 s of rest) under respiratory acidosis by CO 2 rebreathing, alkalosis by hyperventilation, or control. The PCO 2, pH, K + concentration ([K +]), and Na + concentration were measured in venous and arterialized blood. Compound action potentials (M-wave) were elicited to examine the excitability of the sarcolemma. The surface electromyogram (EMG) was recorded to estimate the central drive to the muscle. The lowest venous pH during the exercise period was 7.24 ± 0.03 in controls, 7.31 ± 0.05 with alkalosis, and 7.17 ± 0.04 with acidosis (P < 0.001). The venous [K +] rose to similar maximum values in all conditions (6.2 ± 0.8 mmol/l). The acidification reduced the decline in contraction speed (P < 0.001) but decreased the M-wave area to 73.4 ± 19.8% (P < 0.001) of the initial value. After the first exercise cycle, the M-wave area was smaller with acidosis than with alkalosis, and, after the second cycle, it was smaller with acidosis than with the control condition (P < 0.001). The duration of the M-wave was not affected. Acidification diminished the reduction in performance, although the M-wave area during exercise was decreased. Respiratory alkalosis stabilized the M-wave area without influencing performance. Thus, we did not find a direct link between performance and alteration of excitability of the sarcolemma due to changes in pH in vivo.",
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AU - Shushakov, V.

AU - Maassen, N.

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N2 - Acidification has been reported to provide protective effects on force production in vitro. Thus, in this study, we tested if respiratory acid-base changes influence muscle function and excitability in vivo. Nine subjects performed strenuous, intermittent hand grip exercises (10 cycles of 15 s of work/45 s of rest) under respiratory acidosis by CO 2 rebreathing, alkalosis by hyperventilation, or control. The PCO 2, pH, K + concentration ([K +]), and Na + concentration were measured in venous and arterialized blood. Compound action potentials (M-wave) were elicited to examine the excitability of the sarcolemma. The surface electromyogram (EMG) was recorded to estimate the central drive to the muscle. The lowest venous pH during the exercise period was 7.24 ± 0.03 in controls, 7.31 ± 0.05 with alkalosis, and 7.17 ± 0.04 with acidosis (P < 0.001). The venous [K +] rose to similar maximum values in all conditions (6.2 ± 0.8 mmol/l). The acidification reduced the decline in contraction speed (P < 0.001) but decreased the M-wave area to 73.4 ± 19.8% (P < 0.001) of the initial value. After the first exercise cycle, the M-wave area was smaller with acidosis than with alkalosis, and, after the second cycle, it was smaller with acidosis than with the control condition (P < 0.001). The duration of the M-wave was not affected. Acidification diminished the reduction in performance, although the M-wave area during exercise was decreased. Respiratory alkalosis stabilized the M-wave area without influencing performance. Thus, we did not find a direct link between performance and alteration of excitability of the sarcolemma due to changes in pH in vivo.

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