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This paper provides a mathematical description based on the theory of differential equations, for the dynamics of lactate production and removal. Analytical and numerical results for training/exercise of endurance of athletes are presented based on the common concept of training impulse (Trimp). The relationships between activity, production rate, and removal strategies of lactate are studied. Parameters are estimated from published data. A model for optimum removal of lactate after exercise is developed. The model provides realistic predictions when compared with experimental results. We show some specific examples for the usefulness of the mathematical model by studying some recent problems discussed in the literature. (a) Is interval exercise more beneficial than steady-state exercise? (b) What is the optimum aerobic power during recovery? We discuss whether steady-state exercise gives higher Trimp than interval exercise, when imposing an upper boundary for the lactate concentration as a constraint. The model allows for testing all imaginable kinds of steady-state and interval exercises in search of the optimal exercise regime for individuals with various kinds of characteristics. In general, the dynamic model constitute a powerful tool describing the processes by which the concentration of lactate can be studied and controlled to decrease fatigue and increase endurance.

The objective of this study was to evaluate the 5-year changes of aerobic capacity, fat ratio and flexibility in older Tai Chi Chuan (TCC) practitioners and sedentary controls. Sixty-nine community-dwelling elderly individuals (mean age: 68.6 ± 6.3 years) completed this study. The TCC group (18 M; 17 F) had been practicing TCC regularly for 6.3 ± 3.7 years at baseline and continued training in the study interval. The control group (16 M; 18 F) did not participate in any regular exercise program. A graded bicycle exercise testing was conducted at the baseline and at 5-year to evaluate the age-related decline in aerobic capacity. Triceps and subscapular skinfolds, and thoracolumbar flexibility were also measured. At baseline, the TCC group displayed higher peak oxygen uptake and thoraolumbar flexibility, and lower fat ratio than the control group. At the 5-year follow-up, the TCC group displayed a smaller decrease in than the sedentary group. The annual decrease of in TCC men and women was 0.32 and 0.22 ml · kg^-1 · min^-1, respectively. In the control group, the annual decrease of was 0.50 and 0.36 ml · kg^-1 · min^-1 in men and women, respectively. The TCC group also showed a smaller increase of body fat ratio, and a less decrease of flexibility than the control group. In conclusion, long-term practice of TCC attenuates the age-related decline of aerobic capacity, and it also reduces the increase of body fat ratio in older individuals. TCC may be prescribed as a conditioning exercise for the elderly to maintain their health fitness.

Purpose: To compare the patients operated on for lumbar disc hernia with two different methods in view of pain, disability, physical performance, physical activity and aerobic capacity. Methods: Forty-one patients were included in the study (group I, nucleoplasty – n = 14), (group II, lumbar discectomy – n = 27). Visual Analog Scale (VAS) was performed for pain; Oswestry Disability Index for lumbar disability level; total rolling time, lie/sit, sit and stand, 50 foot walking and five-minute walk tests for physical performance measurements; the Compendium of Physical Activities (CPA) scale for activity level measurement, and VO₂ max measurements for aerobic capacity. Results: In the second month's controls, changes of pain and disability levels were insignificant in both groups, even though pain in nucleoplasty group and disability in discectomy group were found to be better. In performance measurements, group II showed better results in the second postoperative month, whereas group I had better results in the sixth postoperative month. The levels of physical activity in group I, and of aerobic capacity in group II increased significantly. Conclusion: Different physiotherapy approaches are necessary to obtain good results in terms of pain intensity, disability, physical performance, physical activity and aerobic capacity, since these parameters are found to be worse during the sixth month postoperative in patients who had undergone lumbar discectomy.