Apelin as a Potential Regulator of Peak Athletic Performance

Apelin, as a cardiokine/myokine, is emerging as an important regulator of cardiac and skeletal muscle homeostasis. Loss of apelin signaling results in premature cardiac aging and sarcopenia. However, the contribution of apelin to peak athletic performance remains largely elusive. In this paper, we assessed the impact of maximal cardiorespiratory exercise testing on the plasma apelin levels of 58 male professional soccer players. Circulating apelin-13 and apelin-36, on average, increased transiently after a single bout of treadmill exercise; however, apelin responses (Δapelin = peak - baseline values) showed a striking interindividual variability. Baseline apelin-13 levels were inversely correlated with those of Δapelin-13 and Δapelin-36. Δapelin-13 showed a positive correlation with the maximal metabolic equivalent, relative maximal O₂ consumption, and peak circulatory power, whereas such an association in the case of Δapelin-36 could not be detected. In conclusion, we observed a pronounced individual-to-individual variation in exercise-induced changes in the plasma levels of apelin-13 and apelin-36. Since changes in plasma apelin-13 levels correlated with the indicators of physical performance, whole-body oxygen consumption and pumping capability of the heart, apelin, as a novel exerkine, may be a determinant of peak athletic performance.

Relationship between Maximum Force-Velocity Exertion and Swimming Performances among Four Strokes over Medium and Short Distances: The Stronger on Dry Land, the Faster in Water?

Evaluating force-velocity characteristics on dry-land is of the utmost importance in swimming, because higher levels of these bio-motor abilities positively affect in-water performance. However, the wide range of possible technical specializations presents an opportunity for a more categorized approach that has yet to be seized. Therefore, the aim of this study was to identify feasible differences in maximum force-velocity exertion based on swimmers' stroke and distance specialization. To this scope, 96 young male swimmers competing at the regional level were divided into 12 groups, one for each stroke (butterfly, backstroke, breaststroke, and front crawl) and distance (50 m, 100 m, and 200 m). They performed two single pull-up tests, 5-min before and after competing in a federal swimming race. We assessed force (N) and velocity (m/s) exertion via linear encoder. There were no significant differences between pre-post maximum force-velocity exertions, despite the decreasing trend. Force-parameters highly correlated with each other and with the swimming performance time. Moreover, both force (t = -3.60, p < 0.001) and velocity (t = -3.90, p < 0.001) were significant predictors of swimming race time. Sprinters (both 50 m and 100 m) of all strokes could exert significantly higher force-velocity compared to 200 m swimmers (e.g., 0.96 ± 0.06 m/s performed by sprinters vs. 0.66 ± 0.03 m/s performed by 200 m swimmers). Moreover, breaststroke sprinters presented significantly lower force-velocity compared to sprinters specialized in the other strokes (e.g., 1047.83 ± 61.33 N performed by breaststroke sprinters vs. 1263.62 ± 161.23 N performed by butterfly sprinters). This study could provide the foundation for future research regarding the role of stroke and distance specializations in modeling swimmers' force-velocity abilities, thus influencing paramount elements for specific training and improvement towards competitions.

Associations of apelin, leptin, irisin, ghrelin, insulin, glucose levels, and lipid parameters with physical activity during eight weeks of regular exercise training

OBJECTIVES

This study aims to evaluate the effects of 8 weeks of basketball training on apelin, leptin, irisin, ghrelin, insulin, glucose, and blood lipids among basketball players.

METHODS

The exercise groups were given 2 h of basketball training for 5 d a week and for 8 weeks. The control group was randomly selected among the adolescents who did not regularly exercise.

RESULTS

The apelin and ghrelin levels significantly increased; however, leptin, irisin, and insulin levels statistically decreased in the post-exercise group compared to the other groups (p < .05). The results suggest low levels of cholesterol, triglyceride, high-density lipoprotein (HDL), and low-density lipoprotein (LDL) parameters (p < .05).

CONCLUSIONS

This study demonstrated that after 8 weeks of chronic exercise training, apelin and ghrelin levels increased; in contrast, leptin, irisin, and insulin levels decreased. The decrease in leptin and irisin levels is compatible with the pattern of decrease in the lipid levels as a result of chronic exercise.

Investigation of the effect of training on serotonin, melatonin and hematologic parameters in adolescent basketball players

OBJECTIVES

Exercise can improve both health and mood. Some beneficial effects of exercise are attributed to endocrine status. This study aims to evaluate the effect of eight weeks of basketball training on melatonin, serotonin, and hematologic parameters in basketball players.

METHODS

The experimental group was selected form 34 healthy young boys, aged between 13 and 16 years old. The participants were randomly assigned to the control group (n=17) and the exercise group (n=17). The exercise program consisted of 2 h/day aerobic activity of basketball training in 5 days a week for 8 weeks. Venous blood was taken on the day before experiment (pre-exercise) and on the day following the last exercise (post-exercise) and hormone levels were detected by ELISA.

RESULTS

Serotonin and melatonin levels significantly increased in the post-exercise group compared to the other groups (p<0.05). Exercise caused increase in WBC, RBC, HCT and Hb levels (p<0.05) while did not alter PLT, MCH, and PCT levels (p>0.05). This study indicates that an eight weeks-long regular aerobic exercise increased melatonin and serotonin levels, and also altered some hematological parameters.

CONCLUSIONS

In conclusion, it is believed that improvement in levels of serotonin, melatonin, and hematological parameters after eight weeks of regular basketball training in basketball players could be attributed to beneficial effects of exercise. Investigation in other branches of sports and in different gender and age groups would make contribution into exercise physiology and training science.