The purpose of this study was to evaluate the effects of astaxantin（ACT）ingestion on exercise-induced physiological functions. In this experiment we planned to investigate the autonomic nervous system（ANS）and the respiratory metabolism during different exercise intensities in subjects taking astaxantin and those taking placebo. The design of this experiment was a double-blind crossover study.
Eighteen male volunteers（35.8±4.51 years of age）took ACT or placebo（CON）capsule daily for two weeks. Exercise stress tests were done before and after the ingestion period. The exercise load was in the form of running exercise on a treadmill at intensities of 30％, 50％ and 70％ of maximum heart rate（HRmax）．Heart rate variability（HRV），expired gases analysis and blood biochemical parameters were measured. Sympathetic nervous activity（SNA）and parasympathetic nervous activity（PNA）were estimated from the pattern of power density in three frequency ranges on the power spectrum.
During the exercise at an intensity of 70％ HRmax, CVRR and HF/TF increased significantly（p<0.05）after ACT ingestion. Additionally, VE decreased significantly（p<0.05）during exercise at 70％ HRmax after ACT ingestion. These data indicated that after ACT ingestion, SNA was decreased and PNA was enhanced during exercises at 70％ HRmax. Furthermore LDL cholesterol decreased markedly after exercise（p<0.05）and respiratory quotient decreased during exercise. These results suggest that ACT may contribute to enhancement of lipid metabolism. Decrease of respiratory parameters may indicate augmentation of the efficacy of exercise in energy metabolism.
We compared the occurrence patterns of somatosensory evoked potentials（SEP）in the athlete group（soccer players）and non-athlete group. SEP were elicited following separate somatosensory stimulations at the median nerve and at the tibial nerve. P2 latency following tibial nerve stimulation was shorter in the athlete group compared with non-athlete group. On the other hand, no significant differences in latencies following median nerve stimulation were observed between the athlete group and non-athlete group. The N1-P1 amplitudes following tibial nerve stimulation inclined to increase in the athlete group compared to non-athlete group, whereas no significant differences in amplitudes following median nerve stimulation were observed between the two groups. These results indicate that plastic changes in somatosensory cortex may be induced through performance of physical exercises that require skilled movements.
Previous studies have shown that catecholamines are major physiological markers of human stress, and are detectable not only in blood but also in saliva and urine. However the measurement of salivary catecholamines is difficult because of the low concentration and rapid enzymatic degradation.
To investigate whether salivary chromogranin A instead of catecholamines reflects short-term changes of sympathetic nervous activity, we simultaneously measured salivary chromogranin A and plasma catecholamines concentrations at rest and immediately after bicycle ergometry in 13 healthy adults, using an enzyme immunosorbent assay with chromogranin A like immunoreactivity（CgA-like IR）. Salivary CgA-like IR levels significantly increased after cyclic exercise, and related either to blood noradrenaline concentrations or to heart rates（p<0.05）. Moreover, the ratio of salivary CgA-like IR concentrations was significantly correlated with the ratio of heart rates after cyclic exercise of the different workload（p<0.05）. These results indicate that salivary CgA-like IR reflects short-term changes in the activity of the cardiac sympathetic nerves, and may be more useful than salivary catecholamines. Therefore, salivary CgA-like IR can be used as an index of acute alterations in this system.