INTRODUCTION Friedreich’s ataxia (FA) is a rare inherited neurodegenerative disease caused by decreased expression of frataxin, a protein involved in many cellular metabolic processes, including mitochondrial oxidative phosphorylation [1]. In many of these patients, a reduced exercise tolerance and the associated easy fatigability significantly affects quality of life. Our objective was to assess peak exercise capacity in adults with FA as compared to age-matched healthy controls using the classic open circuit method. Moreover, skeletal muscle fractional O2 extraction was evaluated by near infra-red spectroscopy (NIRS), a noninvasive tool able to detect mitochondrial dysfunction in clinical populations [2,3]. METHODS Sixteen FA patients, aged 26±8 years, and sixteen healthy subjects (CTRL), aged 26±3 were included. All patients were able to walk without support, and had a mean total score at the Scale for Assessment and Rating of Ataxia (SARA) of 16±1 points [4]. Each participant performed an incremental exercise on a recumbent cycle ergometer up to voluntary exhaustion. Breath-by-breath pulmonary O2 uptake (VO2), heart rate (HR), and rate of self-perceived exertion (RPE), using the validated Borg’s Scale [5] were determined. Concentration changes of deoxygenated hemoglobin and myoglobin (∆[deoxy(Hb+Mb)]) from resting values, determined by NIRS positioned on vastus lateralis, were considered an index of O2 extraction. RESULTS FA patients attained significant lower peak workload and VO2peak values (57±33 W and 19.2±5.8 ml*kg- 1*min-1, respectively) compared to CTRL (194±64 W and 34.3±9.4 ml*kg-1*min-1, respectively; both p<0.001). A significant (p=0.013) negative correlation was observed between SARA score and VO2peak. Peak HR was 150±20 b*min1, corresponding to 77±11% of the age-predicted maximum value in FA, suggesting that some of FA patients did not attain maximal effort. By contrast, peak HR was 182±10 b*min1 corresponding to 94±4% in CTRL. RPE was similar between FA (16±3.2) and CTRL (18±1.5; p=0.063). Peak ∆[deoxy(Hb+Mb)] was lower in FA (27.8±11.2%) compared to CTRL (56.0±24.9%; p<0.001). CONCLUSIONS FA patients showed a reduced exercise tolerance compared to healthy controls, at least partially attributable to impairment in fractional oxygen extraction at skeletal muscle level. A significant negative correlation was observed between SARA score and VO2peak. However, it should be considered that severe limb coordination deficits in FA disease prevented the optimal execution of the incremental test on the recumbent cycle ergometer up to the maximum effort, thus limiting the interpretation of the results and reducing the applicability of this test as a tool to assess exercise tolerance in FA.
Vukaj, X., Neri, M., Fichera, M., Nanetti, L., Marchini, G., Porcelli, S., Mariotti, C., Marzorati, M., EXERCISE TOLERANCE IN PATIENTS WITH FRIEDREICH’S ATAXIA, Abstract de <<28th Annual Congress of the EUROPEAN COLLEGE OF SPORT SCIENCE>>, (Paris, France, 04-07 July 2023 ), WILEY, Hoboken N.J. 2023: 403-404 [https://hdl.handle.net/10807/340374]
EXERCISE TOLERANCE IN PATIENTS WITH FRIEDREICH’S ATAXIA
Vukaj, Xhuljano;Marzorati, Mauro
2023
Abstract
INTRODUCTION Friedreich’s ataxia (FA) is a rare inherited neurodegenerative disease caused by decreased expression of frataxin, a protein involved in many cellular metabolic processes, including mitochondrial oxidative phosphorylation [1]. In many of these patients, a reduced exercise tolerance and the associated easy fatigability significantly affects quality of life. Our objective was to assess peak exercise capacity in adults with FA as compared to age-matched healthy controls using the classic open circuit method. Moreover, skeletal muscle fractional O2 extraction was evaluated by near infra-red spectroscopy (NIRS), a noninvasive tool able to detect mitochondrial dysfunction in clinical populations [2,3]. METHODS Sixteen FA patients, aged 26±8 years, and sixteen healthy subjects (CTRL), aged 26±3 were included. All patients were able to walk without support, and had a mean total score at the Scale for Assessment and Rating of Ataxia (SARA) of 16±1 points [4]. Each participant performed an incremental exercise on a recumbent cycle ergometer up to voluntary exhaustion. Breath-by-breath pulmonary O2 uptake (VO2), heart rate (HR), and rate of self-perceived exertion (RPE), using the validated Borg’s Scale [5] were determined. Concentration changes of deoxygenated hemoglobin and myoglobin (∆[deoxy(Hb+Mb)]) from resting values, determined by NIRS positioned on vastus lateralis, were considered an index of O2 extraction. RESULTS FA patients attained significant lower peak workload and VO2peak values (57±33 W and 19.2±5.8 ml*kg- 1*min-1, respectively) compared to CTRL (194±64 W and 34.3±9.4 ml*kg-1*min-1, respectively; both p<0.001). A significant (p=0.013) negative correlation was observed between SARA score and VO2peak. Peak HR was 150±20 b*min1, corresponding to 77±11% of the age-predicted maximum value in FA, suggesting that some of FA patients did not attain maximal effort. By contrast, peak HR was 182±10 b*min1 corresponding to 94±4% in CTRL. RPE was similar between FA (16±3.2) and CTRL (18±1.5; p=0.063). Peak ∆[deoxy(Hb+Mb)] was lower in FA (27.8±11.2%) compared to CTRL (56.0±24.9%; p<0.001). CONCLUSIONS FA patients showed a reduced exercise tolerance compared to healthy controls, at least partially attributable to impairment in fractional oxygen extraction at skeletal muscle level. A significant negative correlation was observed between SARA score and VO2peak. However, it should be considered that severe limb coordination deficits in FA disease prevented the optimal execution of the incremental test on the recumbent cycle ergometer up to the maximum effort, thus limiting the interpretation of the results and reducing the applicability of this test as a tool to assess exercise tolerance in FA.
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