CPX was performed using an upper limbs cycle ergometer (Ergoline GmbH, Blitz, Germany). Respiratory gas exchange measurements were obtained breath by breath (Sensormedics, Yorba Linda, CA, USA). Peak oxygen uptake (VO₂max) was recorded at the mean value of VO₂ during the last 20 sec of the test. The ventilatory anaerobic threshold was detected by the use of the V-slope method. Continuous variables were compared between groups using an unpaired t test, categorical variable were compared using a chi-square test. Correlation was performed using the Parson’s correlation coefficient. 

We studied 54 FRDA patients and 22 HC. Age (35.3±13.8 vs 33.4±9.9;p=0.559), gender (M:F 28:27 vs 8:14;p=0.248), and BMI (23.1±4.6 vs 23.0±3.4;p=0.928) did not differ between groups. VO₂max (13.95±4.7 vs 25.68±5.9 mL/Kg/min;p<0.001), peak workload (43.87±12.0 vs 76.18±20.0 watts;p<0.001), and test duration (4.29±2.4 vs 10.93±2.5 min;p<0.001) were reduced in FRDA patients. Sixty-four percent of patients, and 32% of HC reached the anaerobic threshold (p=0.011). VE/VCO₂ slope was higher in FRDA compared to HC (32.87±5.1 vs 28.48±5.9;p=0.002). In FRDA patients, VO₂max inversely correlated with BMI (R=-0.333;p=0.014), interventricular septum thickness (R= -0.281;p=0.039), SARA  (R= -0.434;p=0.001), disease duration (R= -0.397;p=0.003), and 9HPT performance (R= -0.437;p=0.001). VO₂max directly correlated with ADL (R=0.536;p<0.001), and IADL (R=0.385;p=0.004).