Tag: anaerobic threshold

Post-viral fatigue syndrome. A longitudinal assessment in varsity athletes

Abstract:

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.

 

Source: Maffulli N, Testa V, Capasso G. Post-viral fatigue syndrome. A longitudinal assessment in varsity athletes. J Sports Med Phys Fitness. 1993 Dec;33(4):392-9. http://www.ncbi.nlm.nih.gov/pubmed/8035588

 

Aerobic work capacity in chronic fatigue syndrome

Comment on Aerobic work capacity in patients with chronic fatigue syndrome. [BMJ. 1990]

SIR,

The data of Dr Marshall S Riley and colleagues (1) are consistent with our findings (2) that most patients referred with the chronic fatigue syndrome have the effort syndrome-that is, chronic hyperventilation as a consequence of excessive effort and distress.(3)

May we draw attention to three points. Dr Riley and colleagues concluded that the patients could not be hyperventilating because their values of end-tidal partial pressure of carbon dioxide at rest and at peak exercise did not differ significantly from those of the controls.

In our opinion the values published for the controls (35 8 mmHg at rest and 36-3 mmHg at peak exercise) are too low to be accepted as normal. The finding that the patients reached their anaerobic threshold far quicker than did the controls is consistent with the early acidosis on exertion known to occur in chronic hyperventilation. This is a consequence of the depletion of the body’s buffer base reserves,(4) brought about by renal compensation for chronic respiratory alkalosis.(5)

You can read the rest of this comment here: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1664329/pdf/bmj00207-0055b.pdf

 

Source: Rosen SD, King JC, Wilkinson JB, Nixon PG. Aerobic work capacity in chronic fatigue syndrome. BMJ. 1990 Nov 24;301(6762):1217. [Comment] http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1664329/