Table 3.
Studies focused on the long-term effect of physical exercise on blood irisin levels.
| Study | Intervention Description | Length of the Intervention | Weekly Volume | Within-Group Effect Sig. | Between-Groups Effect Sig. | Note |
|---|---|---|---|---|---|---|
| Alyami [25] | Supervised exercise training (SET) | 8 weeks | 2× | - | - | |
| Amanat [26] | Endurance training (ET), resistance training (RT), and combined training (CT) | 12 weeks | 2× to 3× | ↑ * | ↑ ** | * all the EG; ** ET and CT |
| Bagheri [27] | Endurance training (ET) | 8 weeks | 3× | - | - | |
| Bang [28] | Resistance training (RT) vs. resistance training with ursolic acid supplementation (RT + UA) | 8 weeks | 6× | - | ↓ * | * RT |
| Banitalebi [29] | Sprint interval training (SIT), combined endurance and resistance training (A + R) | 10 weeks | 3× | - | - | |
| Besse-Patin [30] | Endurance training | 8 weeks | 5× | - | N/A | |
| Blüher [31] | Exercise and dietary lifestyle program | 1 year | 2× | ↑ | N/A | |
| Boeselt [32] | High-intensity training (HIT) | 12 weeks | 2× | - | - | |
| Bonfante [33] | Combined training (CT) | 24 weeks | 3× | - | ↑ | |
| Briken [34] | Endurance training (ET) | 9 weeks | 2–3× | - | - | |
| Brinkmann [35] | Combined training: males vs. females | 8 weeks | 3× | - | - | |
| Damirchi [36] | Physical training (PT) | 8 weeks | 2× | - | - | |
| de la Torre-Saldaña [37] | Treadmill—6.0–7.9 METs and >8.0 METs | 2 weeks | 5× | ↑ * | N/A | * both |
| Dianatinasab [38] | Endurance training (ET), resistance training (RT), and combined training (CT) | 8 weeks | 3× | - | - | |
| Dündar [39] | Basketball training | 8 weeks | 5× | ↓ | - | |
| Dünnwald [40] | High-intensity interval training (HIIT) vs. continuous moderate-intensity training (CMIT) | 4 weeks | 3× | ↑ * | ↑ * | * HIIT |
| Eaton [41] | High-intensity interval training (HIIT) | 20 days | 2× a day | ↑ | N/A | |
| Ellefsen [42] | Progressive strength training | 12 weeks | 3× | - | N/A | |
| Fernandez-del-Valle [43] | High-intensity interval training (HIIT) | 3 weeks | 3× | ↑ | ↑ | |
| Ghanbari-Niaki [44] | Resistance training (RT) | 9 weeks | 3× | ↑ | - | |
| Hecksteden [45] | Endurance training (ET) and strength training (ST) | 26 weeks | 3× | - | - | |
| Huang [46] | Endurance exercise | 8 weeks | 7× | ↑ | N/A | |
| Huh [47] | Whole-body vibration exercise | 6 weeks | 2× | - | N/A | |
| Jawzal [48] | Military aerobic training | 8 weeks | 7× | ↑ | N/A | |
| Kim [49] | Endurance training (ET), resistance training (RT) | 8 weeks | 5× | ↑ * | ↑ * | * RT |
| Kim [50] | Aquaerobic training (AqT) | 16 weeks | 2× | ↑ | ↑ | |
| Kim [51] | Treadmill walking | 6 weeks | 3× | ↑ | N/A | |
| Korkmaz [52] | Nordic walking (NW), resistance exercise (RE) | 12 weeks | 3× | ↑ * | ↑ * | * Both IG |
| Kuster [53] | Physical training (PT) | 10 weeks | 2× | - | - | |
| Micielska [54] | High-intensity circuit training (HICT) | 5 weeks | 4× | - | - | |
| Miyamoto-Mikami [55] | Endurance training (ET)—healthy young | 8 weeks | 3× | - | - | |
| Endurance training (ET)—middle-aged/older | 8 weeks | 3× | ↑ | ↑ | ||
| Moienneia [56] | Resistance training low (LIRT) vs. high intensity (HIRT) | 8 weeks | 3× | ↓ * | - | * HIRT |
| Moraes [57] | Intradialytic resistance training (IRT) | 6 months | 3× | ↑ | N/A | |
| Motahari Rad [58] | Concurrent aerobic-resistance (A-R) and concurrent resistance-aerobic (R-A) training | 12 weeks | 3× | ↑ * | ↑ * | * Both IG |
| Murawska-Cialowicz [59] | CrossFit training: males vs. females | 3 months | 2× | ↓ * | - | * females |
| Murawska-Cialowicz [60] | High-intensity interval training (HIIT) | 8 weeks | 2× | ↑ * | - | * HIIT |
| Neumayr [61] | Golf vs. Nordic walking or e-biking | 1 week | 7× | ↑ * | N/A | * only golf group |
| Norheim [62] | Combined endurance and strength training: normoglycaemic and normal weight | 12 weeks | 4× | - | - | |
| Ozan [63] | Strength training with thera-band | 8 weeks | 3× | - | N/A | |
| Özbay [64] | Outdoor running (OR) vs. indoor running (IR) | 18 weeks | 4× | ↓ * | - | * IR |
| Palacios-Gonzales [65] | School-based physical activity program: normal weight | 8 months | 5× | - | - | |
| Pekkala [15] | Endurance training (ET) vs. combined endurance and resistance training (ET + RT) | 21 weeks | 2× (ET) or 2× (ET) + 2× (RT) | - | - | |
| Planella-Farrugia [66] | Low-intensity resistance training (LIRT) | 16 weeks | 2× | ↑ * | - | * LIRT |
| Prestes [67] | Resistance training linear periodization (LP) and undulating periodization (UP) | 16 weeks | 2× | - | - | |
| Rashid [68] | Long-term moderate physical exercise: normal weight | 6 months | 7 times | ↑ * | ↑ | * both |
| Rashti [69] | High-intensity interval (HIIT) and moderate-intensity training (MIIT) | 10 weeks | 3× | ↑* | - | * HIIT |
| Roh [70] | Taekwondo in obese children | 16 weeks | 5× | ↓ | ↓ | |
| Sezgin [71] | Endurance training (ET) and personalized nutrition programs: normal weight | 8 weeks | 7× | - | - | |
| Shabani [72] | Resistance training (RT), Endurance training (ET), and concurrent (endurance + resistance) training (CT) | 8 weeks | 3× | ↓ * | - | * RT and CT |
| Scharhag-Rosenberger [73] | High-repetition resistance training (HRRT) | 6 months | 3× | - | ↓ | |
| Śliwicka [74] | Climb 4000 m peaks in the Mont Blanc massif | 14 days | 7× | ↓ | N/A | |
| Szumilewicz [75] | Structured group fitness program—very active (VA) vs. less active (LA) groups | 8 weeks | ≥3× (VA) <3× (LA) | ↓ * | - | * LA |
| Tibana [76] | Resistance training (RT): obese vs. normal weight | 16 weeks | 3× | ↓ * | ↑ ** | * normal weight; ** obese |
| Tsuchiya [77] | Cycle ergometer—sprint training (ST) vs. two consecutive training (TCT) | 4 weeks | 5× (ST) 2–3× (TCT) | ↓ * | - | * both |
| Vieira [78] | Resistance training very high supervision (VHS) vs. high supervision (HS) | 16 weeks | 2× | - | - | |
| Walentukiewicz [79] | Nordic walking (NW) | 12 weeks | 3× | - | - | |
| Weber-Rajek [80] | Pelvic floor muscle training (PMT) | 4 weeks | 3× | ↑ * | - | * PMT |
| Witek [81] | Workload during the competitive season | 8 months | - | - | N/A | |
| Zhao [82] | Resistance training (RT) | 12 weeks | 2× | ↑ * | ↑ | * RT |
Note: ↑ = increased levels; ↓ = decreased levels; N/A not applicable; *, ** = groups’ specification.