| Study |
Participants |
Design |
Outcome |
| Human Studies demonstrating an increase in serum irisin after acute exercise |
| Huh et al. [27] |
15 young moderately trained lean healthy males |
8-week exercise intervention of 3 sprint sessions/week. Blood samples before and 30 mins after first and last session. |
At first session, irisin was é30 min after sprinting exercise.
After 8 weeks, exercise induction effect was lost. |
| Kraemer et al. [28] |
7 young healthy lean males
5 young healthy lean females |
Exercise test at 60%VO2max for 90min with samples taken at 0,54,90 min, and after 20 min rest.
Females completed protocol during mid-follicular and then mid-luteal phase of cycle |
Irisin é by ~20% in first 54min of exercise, declined to baseline by 20 mins of rest, regardless of gender, or phase of menstrual cycle. |
| Norheim et al. [29] |
13 normglycaemic lean men age 40-65 years.
13 overweight pre-diabetic men age 40-65 years. |
12-week intervention of 4x weekly strength and endurance training.
Exercise test before and after intervention at 70%VO2max. |
In lean normoglycaemic men, circulating irisin é1.2 fold immediately after acute exercise.
This only occurred in the overweight group after 12 wks training.
12-weeks training tended to decrease plasma irisin.
12 weeks of exercise éexpression FNDC5 mRNA in skeletal muscle. |
| Lee et al. [23] |
4 females and 6 males; lean, young and otherwise healthy |
Maximal exercise test at VO2max.
Submaximal 1 hr exercise test at 40% VO2max. |
1hr submaximal exercise éserum irisin 2.8-3.1 fold, with lesser increase after maximal exercise |
| Human studies demonstrating no increase in serum irisin after acute or long term exercise |
| Kuridova et al. [34] |
Study 1: described in Table 3.
Study 2: 16 older (~36.5yrs) overweight individuals |
Study 2:12-week intervention of 3x weekly 1hr strength and endurance training.
Acute bout of 1hr exercise at 70% VO2max, serum sample 1 hr later |
Neither 3 months of exercise or acute bout of exercise resulted in altered skeletal muscle FNDC5 mRNA or circulating irisin. |
| Pekkala et al. [35] |
Study 1: 17 overweight middle aged men
Study 2: 10 young lean men and 11 old lean men
Study 3: 9 older normal weight men/group |
Study 1: 1hr acute exercise at 50% VO2max.
Study 2: acute resistance exercise
Study 3: 21 weeks of 2 or 4 times weekly endurance alone or also strength training |
Study 1 and Study 3: No significant change in skeletal muscle PGC1α /FNDC5 mRNA or serum irisin
Study 2: No alternations in serum irisin before, during or after exercise bout. Skeletal muscle FNDC5 mRNA é in young men only. |
| Bostrom et al. [19] |
8 male non-diabetic obese individuals |
10-week intervention of 4-5x weekly aerobic training at 65% VO2max. Blood samples and skeletal muscle biopsy obtained 1-2 weeks before and 48 hours after intervention |
2 fold é in serum irisin after exercise. |
| Human Studies demonstrating no increase in irisin after long term exercise |
| Hecksteden et al. [36] |
RCT in 112 healthy individuals, ages 30-60 with BMI<30 |
Intervention groups completed either 45 min aerobic training or strength training 3x weekly exercise for 26 weeks. Control group remained sedentary. |
No difference between circulating irisin. |
| Hofmann et al. [37] |
19 moderate activity and
19 high activity individuals with anorexia nervosa |
Physical activity was measured over 3 days. Fasting serum samples collected. |
No difference in circulating irisin. |
| Human Studies demonstrating an increase in irisin after long term exercise |
| Bluher et al. [38] |
65 obese children age 7-18 years |
Intervention of a 1 year obesity therapy program of ~150min/week exercise + diet counselling and psychological education and support. |
Circulating irisin é by 12 % after intervention. |
| Norheim et al. [39] |
As described above. 12 weeks of exercise é expression of PGCα and FNDC5 mRNA in skeletal muscle. |
