Thepacing strategy may be defined as the process in which the total energy expenditure during exercise is regulated on a moment-to-moment basis in order to ensure that the exercise bout can be completed in a minimum time and without a catastrophic biological failure. Experienced athletes develop a stable template of the power outputs they are able to sustain for different durations of exercise, but it is not known how they originally develop this template or how that template changes with training and experience. While it is understood that the athlete's physiological state makes an important contribution to this process, there has been much less interest in the contribution that the athlete's emotional status makes. The aim of this review is to evaluate the literature of physiological, neurophysiological and perceptual responses during exercise in order to propose a complex model interpretation of this process which may be a critical factor determining success in middle- and long-duration sporting competitions. We describe unconscious/physiological and conscious/emotional mechanisms of control, the focus of which are to ensure that exercise terminates before catastrophic failure occurs in any bodily system. We suggest that training sessions teach the athlete to select optimal pacing strategies by associating a level of emotion with the ability to maintain that pace for exercise of different durations. That pacing strategy is then adopted in future events. Finally, we propose novel perspectives to maximise performance and to avoid overtraining by paying attention also to the emotional state in training process.

We investigated the effects of short duration running training on resting and exercise lung function in healthy prepubescent children. One trained group (TrG) (n = 9; three girls and six boys; age = 9.7 +/- 0.9 year) participated in 8 weeks of high-intensity intermittent running training and was compared to a control group (ContG) (n = 9; four girls and five boys; age = 10.3 +/- 0.7 year). Before and after the 8-week period, the children performed pulmonary function tests and an incremental exercise test on a cycle ergometer. After the 8-week period, no change was found in pulmonary function in ContG. Conversely, an increase in forced vital capacity (FVC) (+7 +/- 4% ; P = 0.026), forced expiratory volume in one second (+11 +/- 6% ; P = 0.025), peak expiratory flows (+17 +/- 4% ; P = 0.005), maximal expiratory flows at 50% (+16 +/- 10% ; P = 0.019) and 75% (+15 +/- 8% ; P = 0.006) of FVC were reported in TrG. At peak exercise, TrG displayed higher values of peak oxygen consumption (+15 +/- 4% ; P < 0.001), minute ventilation (+16 +/- 5% ; P = 0.033) and tidal volume (+15 +/- 5% ; P = 0.019) after training. At sub-maximal exercise, ventilatory response to exercise DeltaV(E)/DeltaV(CO(2)) was lower (P = 0.017) in TrG after training, associated with reduced end-tidal partial oxygen pressure (P < 0.05) and higher end-tidal partial carbon dioxide pressure (P = 0.026). Lower deadspace volume relative to tidal volume was found at each stage of exercise in TrG after training (P < 0.05). Eight weeks of high-intensity intermittent running training enhanced resting pulmonary function and led to deeper exercise ventilation reflecting a better effectiveness in prepubescent children.

We assessed expiratory airflow limitation (exp FL) in 18 healthy prepubescent children (6 girls and 12 boys, 10.1 +/- 0.3 years old), and examined how it might modulate regulation of tidal volume (V(T)) during exercise. The children performed a maximal incremental exercise on a cycle ergometer, preceded and followed by pulmonary function tests. Throughout exercise, breathing flow-volume loops were plotted into the maximal flow-volume loop (MFVL) measured at rest. End-expiratory and end-inspiratory lung volumes were estimated by measuring expiratory reserve volume relative to forced vital capacity (ERV/FVC), and inspiratory reserve volume relative to forced vital capacity (IRV/FVC), respectively. The exp FL, expressed as a percentage of V(T), was defined as the part of the tidal breath meeting the boundary of the MFVL. Ten children (FL) presented an exp FL at peak exercise (range, 16-78% of V(T)), and the remaining 8 constituted a non-flow-limited group (NFL). At peak exercise, FL presented a higher IRV/FVC and lower ERV/FVC (P < 0.01) than NFL children, demonstrating two different exercise breathing patterns. These results suggest that the NFL regulated V(T) at high lung volume, avoiding exp FL, while the FL breathed at low lung volume, leading to exp FL. At peak exercise, FL presented lower values of minute ventilation (P<0.05) and oxygen uptake (P<0.05) than NFL. Nevertheless, oxygen arterial saturation and dyspnea were similar in the two groups. In conclusion, ventilatory constraints may occur in healthy prepubescent children and result in relative dynamic hyperinflation or expiratory flow limitation.

According to the current literature, we would like to emphasize that to ensure an optimal allowance of vitamin C, we advise 1 g daily intake of vitamin C supplementation, accompanied by a diet rich in fruits and vegetables.