Total body aerobic capacity as measured by maximal graded cycle ergometry in healthy controls and MELAS subjects and effect of single dose and steady-state L-arginine therapy in MELAS subjects.

Key: Work—This is a physical quantification of the force operating on a mass that causes it to change its location.% maximum work at AT (anaerobic threshold) is the work in watts at the AT/maximum work in watts achievedPeak work is the maximum work in watts achieved/ weight in kg; % maximum heart rate at AT (anaerobic threshold) is the heart rate at the anaerobic threshold/maximum heart rate achieved; VO2—Amount of Oxygen taken up at the lungs, usually expressed in ml/kg/min. To all intents and purposes this is equal to the uptake at the cellular level (QO2) as there is minimal facility in the body to store oxygen. VCO2—Amount of Carbon dioxide exhaled, usually expressed in ml/kg/min. This is not the same as cellular CO2 production (QCO2) except in steady state. A steady state is not achieved during exercise testing with a ramp protocol. Hyperventilation increases VCO2 but not QCO2. VO2 Max- The maximum amount of oxygen the body can use expressed as ml/kg/min. It is defined as the point where the VO2 plateaus despite an increase in work rate. It is not the same as Peak VO2. The value is different for different forms of ergometry. The true VO2 max has no volitional component as it represents a physiological endpoint. VE/VO2 = ventilatory equivalent for oxygen and is the ratio of minute ventilation to oxygen uptake by the lungs; VE/VCO2 = ventilatory equivalent for carbon dioxide and is the ratio of minute ventilation to carbon dioxide excretion by the lungs; Anaerobic threshold (AT) is the timepoint at which the VE/VCO2 and VE/VO2 cross which occurs ~ at a respiratory quotient (RQ) of 1.0; Anaerobic Threshold, is usually expressed in mls. of oxygen uptake per kg body weight per minute. This is the oxygen uptake (VO2) at which anaerobic ATP synthesis supplements (not replaces) aerobic ATP synthesis and may reflect oxygen demand exceeding supply with subsequent production of lactic acid. It is thus an objective marker of exercise capacity/physiological reserve. In normal subjects it occurs at 35–80% of VO2 max.VO2/HR = O2 pulse (O2 consumption per heart beat)1 = baseline; 2 = single dose L-arginine; 3 = steady state L-arginine X 6 wks; SD = standard deviation@ Maximal oxygen uptake (VO2max) was expressed as a percentage of predicted norms for VO2max [16]* comparison of MELAS baseline versus MELAS single dose or MELAS baseline versus MELAS steady-state L-arginine therapy using paired T-test with two-tailed P value** comparison of baseline MELAS versus control group using Unpaired T-test with two-tailed P value*** statistically significant# comparison of baseline MELAS versus control group using the Wilcoxon-Mann-Whitney test or Wilcoxon rank-sum test which is a nonparametric test of the null hypothesis that two populations are the same against an alternative hypothesis which is used for non-normal population distributionsTotal body aerobic capacity as measured by maximal graded cycle ergometry in healthy controls and MELAS subjects and effect of single dose and steady-state L-arginine therapy in MELAS subjects.