European journal of applied physiology and occupational physiology
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Eur J Appl Physiol Occup Physiol · Jan 1996
Randomized Controlled Trial Clinical TrialThe effects of buffer ingestion on metabolic factors related to distance running performance.
We examined the effects of sodium bicarbonate (BIC) and sodium citrate (CIT) ingestion on distance running performance. Seven male runners [mean VO2max = 61.7 (SEM 1.7) ml.kg-1.min-1] performed three 30-min treadmill runs at the lactate threshold (LT) each followed by a run to exhaustion at 110% of LT. The runs were double-blind and randomly assigned from BIC (0.3 g.kg body mass-1), CIT (0.5 g.kg body mass-1) and placebo (PLC, wheat flour, 0.5 g.kg body mass-1). ⋯ Blood [HCO3-] was significantly higher (P < or = 0.05) during exercise for BIC compared to PLC. TIME-EX was not significantly different among treatments: BIC 287 (SEM 47.4)s; CIT 172.8 (SEM 29.7)s; and PLC 222.3 (SEM 39.7)s. Despite the fact that buffer ingestion produced favourable metabolic conditions during 30 min of high intensity steady-state exercise, a significant improvement in the subsequent maximal exercise run to exhaustion did not occur.
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Eur J Appl Physiol Occup Physiol · Jan 1996
Randomized Controlled Trial Clinical TrialPhysical work capacity in dynamic exercise with differing muscle masses in healthy young and older men.
Ten young (aged 23-30 years) and nine older (aged 54-59 years) healthy men with similar estimated limb muscle volumes performed, in random order, three different types of ergometer exercise tests (one-arm cranking, two-arm cranking, and two-leg cycling) up to the maximal level. Values for work load (WL), peak oxygen consumption (V0(2)), peak heart rate (HR), peak ventilation (V(E)), respiratory gas exchange ratio (R), recovery blood lactate concentration [La-], and rating of perceived exertion (RPE) were compared between the age-groups in the given exercise modes. No significant age-related differences in WL, peak V0(2), peak HR, R, [La-], or RPE were found in one-arm or two-arm cranking. ⋯ In summary, the older men with similar sizes of estimated arm and leg muscle volumes as the young men had a reduced physical work capacity in two-leg cycling. In one-arm or two-arm cranking, no significant difference in work capacity was found between the age-groups. These results indicate, that in healthy men, age, at least up to the 6th decade of life, is not necessarily associated with a decline in physical work capacity in exercises using relatively small muscle groups, in which the limiting factors are more peripheral than central.
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Eur J Appl Physiol Occup Physiol · Jan 1996
Physiological and subjective responses to thermal transients of exercising subjects dressed in cold-protective clothing.
In cold conditions variations in the physical activity of clothed individuals and rest periods in a moderate temperature may result in a disturbance of heat balance and thermal comfort of the individual, in particular when sweating occurs. The purpose of the study was to examine thermal responses in persons dressed in winter clothing during changes of exercise intensity (high to low) and ambient temperature, and to investigate whether there were any effects on these responses due to fibre material (wool and synthetic). Two types of transient condition were studied, an exercise level transient (E) and a temperature transient (T). ⋯ The wool fibre material resulted in a slightly higher mean skin temperature (about 0.3 degree C) during exercise, but no differences in subjective responses were found. The rest period had only a small influence on the subsequent thermal responses. The interindividual variations in thermal responses were large.
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Eur J Appl Physiol Occup Physiol · Jan 1995
Clinical TrialDoes the threshold of transcutaneous partial pressure of carbon dioxide represent the respiratory compensation point or anaerobic threshold?
On reaching the respiratory compensation point (RCP) during rapidly increasing incremental exercise, the ratio of minute ventilation (VE) to CO2 output (VCO2) rises, which coincides with changes of arterial partial pressure of carbon dioxide (PaCO2). Since PaCO2 changes can be monitored by transcutaneous partial pressure of carbon dioxide (PCO2,tc) RCP may be estimated by PCO2,tc measurement. Few available studies, however, have dealt with comparisons between PCO2,tc threshold (TAT) and lactic, ventilatory or gas exchange threshold (VAT), and the results have been conflicting. ⋯ At TAT, power output [P, 294 (SD 40) W], VO2 [4.18 (SD 0.57) l.min.1] and [la(-)] [4.40 (SD 0.64) mmol.l-1] were significantly higher than those at VAT[P 242 (SD 26) W, VO2 3.56 (SD 0.53) l.min-1 and [la(-)]b 3.52 (SD 0.75), mmol.l-1 respectively], but close to those at RCP [P 289 (SD 37) W; VO2 3.97 (SD 0.43) l.min-1 and [la(-)]b 4.19 (SD 0.62) mmol.l-1, respectively]. Accordingly, linear correlation and regression analyses showed that P, VO2 and [la(-)]b at TAT were closer to those at RCP than at VAT. In conclusion, the TAT reflected the RCP rather than VAT during rapidly increasing incremental exercise.
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Eur J Appl Physiol Occup Physiol · Jan 1995
Clinical TrialModulation of the human nociceptive reflex by cyclic movements.
During static conditions the nociceptive reflex is known to vary as a function of, for example, the stimulus position, stimulus intensity, and muscle contraction. The aim of the present human study was to investigate whether the reflex and the corresponding perception of pain are modulated by cyclic movements of the limb involved. Reflexes, evoked by nociceptive electric stimulation of the sural nerve, were recorded from the biceps femoris and the rectus femoris muscles in eight volunteers. ⋯ Knee joint angle recordings showed that the largest angle variations occurred for the dynamic conditions and were only marginally disturbed for the isometric conditions. A given stimulus intensity evoked the highest pain intensity during isometric contractions. This indicates that there would seem to be no causal relationship between the size of the nociceptive reflex and the pain intensity.