Plasma irisin levels progressively increase in response to increasing exercise workloads in young, healthy, active subjects

Abstract

Background: Irisin, a recently discovered myokine, has been shown to induce browning of white adipose tissue, enhancing energy expenditure and mediating some of the beneficial effects of exercise. We aimed to estimate the time frame of changes in irisin levels after acute exercise and the effect of different exercise workloads and intensities on circulating irisin levels immediately post-exercise. Methods: In a pilot study, four healthy subjects (22.5G1.7 years) underwent maximal workload exercise (maximal oxygen consumption, VO 2 max ) and blood was drawn at prespecified intervals to define the time frame of pre-and post-exercise irisin changes over a 24-h period. In the main study, 35 healthy, non-smoking (23.0G3.3 years) men and women (nZ20/15) underwent three exercise protocols R48-h apart, in random order: i) maximal workload (VO 2 max ); ii) relative workload (70% of VO 2 max /10 min); and iii) absolute workload (75 W/10 min). Blood was drawn immediately pre-exercise and 3 min post-exercise. Results: In the pilot study, irisin levels increased by 35% 3 min post-exercise, then dropped and remained relatively constant. In the main study, irisin levels post-exercise were significantly higher than those of pre-exercise after all workloads (all, P!0.001). Post-to-pre-exercise differences in irisin levels were significantly different between workloads (PZ0.001), with the greatest increase by 34% following maximal workload (PZ0.004 vs relative and absolute). Conclusions: Circulating irisin levels were acutely elevated in response to exercise, with a greater increase after maximal workload. These findings suggest that irisin release could be a function of muscle energy demand. Future studies need to determine the underlying mechanisms of irisin release and explore irisin's therapeutic potential.

Exercise regulation of adipose tissue

“…Using this technique circulating irisin was increased by both acute exercise (35% increase; P < 0.001) 50 and chronic exercise (1.2-fold in human subjects after 12 wks of aerobic interval training; P < 0.05). 46,50 Thus, studies have shown that both resistance 45 and endurance exercise 27,46,50 can increase circulating irisin in human subjects. The function of the exercise-induced increase in circulating irisin has been difficult to determine in human subjects.…”

“…More recently, studies have used mass spectrometry to quantify the amount of circulating irisin post-exercise in humans. 46,50 This technique allows for quantification of circulating human irisin in an antibody-independent manner. Using this technique circulating irisin was increased by both acute exercise (35% increase; P < 0.001) 50 and chronic exercise (1.2-fold in human subjects after 12 wks of aerobic interval training; P < 0.05).…”

“…46,50 This technique allows for quantification of circulating human irisin in an antibody-independent manner. Using this technique circulating irisin was increased by both acute exercise (35% increase; P < 0.001) 50 and chronic exercise (1.2-fold in human subjects after 12 wks of aerobic interval training; P < 0.05). 46,50 Thus, studies have shown that both resistance 45 and endurance exercise 27,46,50 can increase circulating irisin in human subjects.…”

Irisin and Fibronectin Type III Domain-Containing 5 Responses to Exercise in Different Environmental Conditions

“…However, the participants in this study were college-aged males, relatively lean, and fit and no increases in irisin or FNDC5 mRNA were observed during exercise and cold exposure contrary to previous research. In similarly fit individuals, based on BMI and VO2max, and age (18-30 years) increases in circulating irisin were observed immediately after a treadmill VO2max test (7). Physically inactive, individuals, age 45-60, have also shown increases in irisin levels during cycling exercise (25).…”

Different Sports in Adolescence: Effect on Lipid Profile, Glucose Metabolism, Body Composition, Bone Density, Bone Quality, Bone Markers, Vascular Function and Structure, Pituitary and Hypothalamic Antibodies

“…more than two hours three times a week, a beneficial influence can be observed on the lipid profile, insulin sensitivity, cardiovascular system, muscle, bone mass and density. [1][2][3] To our knowledge, however, it is not known which is the most healthiest sport and furthermore how each sport influences the different parameters. On the other hand contact sports which imply tackles such as rugby or hockey expose the athlete to the risk of brain trauma which may cause different hypothalamic and pituitary hormonal deficits.…”