Authors: Brown, Peter¹; Sharpe, Graham²; Johnson, Michael²

Source: European Journal of Applied Physiology, Volume 104, Number 1, September 2008 , pp. 111-117(7)

Publisher: Springer

Abstract:

Although reduced blood lactate concentrations ([lac⁻]_B) have been observed during whole-body exercise following inspiratory muscle training (IMT), it remains unknown whether the inspiratory muscles are the source of at least part of this reduction. To investigate this, we tested the hypothesis that IMT would attenuate the increase in [lac⁻]_B caused by mimicking, at rest, the breathing pattern observed during high-intensity exercise. Twenty-two physically active males were matched for 85% maximal exercise minute ventilation <EquationSource Format="TEX">$$ left( {dot V_{{text{E}}} max } right) $$</EquationSource> and divided equally into an IMT or a control group. Prior to and following a 6 week intervention, participants performed 10 min of volitional hyperpnoea at the breathing pattern commensurate with 85% <EquationSource Format="TEX">$$ dot V_{{text{E}}} max . $$</EquationSource> The IMT group performed 6 weeks of pressure-threshold IMT; the control group performed no IMT. Maximal inspiratory mouth pressure increased (mean ± SD) 31 ± 22% following IMT and was unchanged in the control group. Prior to the intervention in the control group, [lac⁻]_B increased from 0.76 ± 0.24 mmol L⁻¹ at rest to 1.50 ± 0.60 mmol L⁻¹ (P < 0.05) following 10 min volitional hyperpnoea. In the IMT group, [lac⁻]_B increased from 0.85 ± 0.40 mmol L⁻¹ at rest to 2.02 ± 0.85 mmol L⁻¹ following 10 min volitional hyperpnoea (P < 0.05). After 6 weeks, increases in [lac⁻]_B during volitional hyperpnoea were unchanged in the control group. Conversely, following IMT the increase in [lac⁻]_B during volitional hyperpnoea was reduced by 17 ± 37% and 25 ± 34% following 8 and 10 min, respectively (P < 0.05). In conclusion, increases in [lac⁻]_B during volitional hyperpnoea at 85% <EquationSource Format="TEX">$$ dot V_{{text{E}}} max $$</EquationSource> were attenuated following IMT. These findings suggest that the inspiratory muscles were the source of at least part of this reduction, and provide a possible explanation for some of the IMT-mediated reductions in [lac⁻]_B, often observed during whole-body exercise.

Keywords: Respiratory muscle training; Diaphragm; Intercostal muscles; Blood lactate concentration; Hyperventilation

Document Type: Research article

DOI: http://dx.doi.org/10.1007/s00421-008-0794-7

Affiliations: 1: School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK, Email: peter.brown@ntu.ac.uk 2: School of Science and Technology, Nottingham Trent University, Nottingham, NG11 8NS, UK

Publication date: 2008-09-01

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