Patients with McArdle's disease (McA) typically show the "second-wind" phenomenon, a sudden decrease in heart rate (HR) and an improved exercise tolerance occurring after a few minutes of exercise. In the present study, we investigated whether in McA a first bout of exercise determines a second wind during a second bout, separated by the first by a few minutes of recovery. Eight McA (44 ± 4 yr) and a control group of six mitochondrial myopathy patients (51 ± 6 yr) performed two repetitions (CWR1 and CWR2) of 6-min constant work rate exercise (∼50% of peak work rate) separated by 6-min (SHORT) or 18-min (LONG) recovery. Pulmonary O 2 uptake (VO2), HR, cardiac output, rates of perceived exertion, vastus lateralis oxygenation changes in deoxygenated Hb and myoglobin Mb concentrations, A[deoxy(Hb+Mb)], by near-infrared spectroscopy were determined. In McA, VO2 (0.86 ± 0.2 vs. 0.95 ± 0.1 l/min), HR (113 ± 10 vs. 150 ± 13 beats/min), cardiac output (11.6 ± 0.6 vs. 15.0 ± 0.8l/min), and rates of perceived exertion (11 ± 2 vs. 14 ± 3) were lower, whereas A[deoxy(Hb+Mb)] was higher (14.7 ± 2.3 vs. -0.1 ± 4.6%) in CWR2-SHORT vs. CWR1; the "overshoot" of A[deoxy(Hb+Mb)] and the "slow component" of VO2 kinetics disappeared in CWR2-SHORT. No differences (vs. CWR1) were observed in McA during CWR2-LONG, or in mitochondrial myopathy patients during both CWR2-SHORT and -LONG. A second-wind phenomenon was observed in McA during the second of two consecutive 6-min constant-work rate submaximal exercises. The second wind was associated with changes of physiological variables, suggesting an enhanced skeletal muscle oxidative metabolism. The second wind was not described after a longer (18-min) recovery period.

The "second wind" in McArdle's disease patients during a second bout of constant work rate submaximal exercise / S. Porcelli, M. Marzorati, M. Belletti, G. Bellistri, L. Morandi, B. Grassi. - In: JOURNAL OF APPLIED PHYSIOLOGY. - ISSN 8750-7587. - 116:9(2014 May 01), pp. 1230-1237.

The "second wind" in McArdle's disease patients during a second bout of constant work rate submaximal exercise

S. Porcelli
Primo
;
G. Bellistri;B. Grassi
Ultimo
2014

Abstract

Patients with McArdle's disease (McA) typically show the "second-wind" phenomenon, a sudden decrease in heart rate (HR) and an improved exercise tolerance occurring after a few minutes of exercise. In the present study, we investigated whether in McA a first bout of exercise determines a second wind during a second bout, separated by the first by a few minutes of recovery. Eight McA (44 ± 4 yr) and a control group of six mitochondrial myopathy patients (51 ± 6 yr) performed two repetitions (CWR1 and CWR2) of 6-min constant work rate exercise (∼50% of peak work rate) separated by 6-min (SHORT) or 18-min (LONG) recovery. Pulmonary O 2 uptake (VO2), HR, cardiac output, rates of perceived exertion, vastus lateralis oxygenation changes in deoxygenated Hb and myoglobin Mb concentrations, A[deoxy(Hb+Mb)], by near-infrared spectroscopy were determined. In McA, VO2 (0.86 ± 0.2 vs. 0.95 ± 0.1 l/min), HR (113 ± 10 vs. 150 ± 13 beats/min), cardiac output (11.6 ± 0.6 vs. 15.0 ± 0.8l/min), and rates of perceived exertion (11 ± 2 vs. 14 ± 3) were lower, whereas A[deoxy(Hb+Mb)] was higher (14.7 ± 2.3 vs. -0.1 ± 4.6%) in CWR2-SHORT vs. CWR1; the "overshoot" of A[deoxy(Hb+Mb)] and the "slow component" of VO2 kinetics disappeared in CWR2-SHORT. No differences (vs. CWR1) were observed in McA during CWR2-LONG, or in mitochondrial myopathy patients during both CWR2-SHORT and -LONG. A second-wind phenomenon was observed in McA during the second of two consecutive 6-min constant-work rate submaximal exercises. The second wind was associated with changes of physiological variables, suggesting an enhanced skeletal muscle oxidative metabolism. The second wind was not described after a longer (18-min) recovery period.
Exercise tolerance; Myophoshorylase deficiency; Near-infrared spectroscopy; V̇; Adult; Exercise; Exercise Test; Exercise Tolerance; Female; Glycogen Storage Disease Type V; Humans; Male; Middle Aged; Oxygen Consumption; Physical Exertion; Physiology; Physiology (medical); Medicine (all)
Settore BIO/09 - Fisiologia
1-mag-2014
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/2434/301584
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