Post-viral fatigue syndrome. A longitudinal assessment in varsity athletes.
Maximal oxygen uptake, anaerobic threshold (AT), isometric strength of the elbow flexor and knee extensor muscles, isometric strength endurance exhaustion time (prolonged contraction at 66% of maximal isometric strength), uphill sprinting exhaustion time were longitudinally studied in eight varsity endurance runners with post-viral fatigue syndrome (PVFS). Prolonged impairment of exercise performance is evident during the course of PVFS. Although maximal oxygen uptake (VO2max) had returned to pre-infection values 13 months after the viral illness (4.160 vs 4.0 L.min-1), AT was still significantly reduced [52 ml.kg-1.min-1, 18.6 km.hr-1, 176 bpm, and 82% of VO2max vs. 49.1 ml.kg-1.min-1 (p < 0.05), 175 bpm (NS), 17.2 km.hr-1 (p < 0.01) and 79% of VO2max (NS)]. Maximal isometric contraction strength of the upper limb remained constant (282 N vs. 274 N), while knee extensor muscles strength decreased significantly (730 N vs. 701 N, p < 0.05). Strength endurance was still significantly reduced by the end of the study (arm average pre-infection: 46.2 sec; end of study: 29.3 sec, p < 0.001; leg average pre-infection: 66.4 sec; end of study: 49.1 sec, p < 0.01). Up hill sprinting time was similarly reduced by the end of the study period (29.3 sec vs. 16.2 sec, p < 0.01). Both aerobic and anaerobic exercise variables are seriously affected by post-viral fatigue syndrome, and one year may not be sufficient to fully recover.
Department of Orthopaedic Surgery, University of Aberdeen Medical School, Scotland.
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Maffulli
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Capasso
D000328:Adult; D015308:Anaerobic Threshold / Q000502:physiology; D015444:Exercise / Q000502:physiology*; D015673:Fatigue Syndrome, Chronic / Q000503:physiopathology*; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D009132:Muscles / Q000502:physiology; D010101:Oxygen Consumption; D010807:Physical Endurance / Q000502:physiology; D012420:Running / Q000502:physiology