. 2021 Sep 3;10(9):868. doi: 10.3390/biology10090868

Table 1.

Summarize of studies investigating the acute effects of interval training on immune outcomes.

Study	Participants	Design	Modality/Interval Protocol	Results
Monje et al. 2020 [43]	20 runners (10 men age: 21.9 ± 0.8 years; 10 women age: 25.8 ± 6.2 years)	Clinical trial	Running HIIT—10 bouts of 4 min at 90% of v $\dot{V}$ O_2max interspersed by 2 min of passive recovery	↑ salivary IgA concentration 20 min after exercise
Wahl et al. 2020 [44] 12 men triathletes and cyclists (age: 24.7 ± 3.4 years) Randomized cross-over trial			Cycling HIIT—4 bouts of 4 min at 90–95% of peak power interspersed by 3 min of passive recovery	↔ leucocyte count; ↓ lymphocyte count 30 min, and 60 min after exercise; ↑ neutrophil count 180 min after exercise; ↔ mixed cell count
			Cycling HIIT—4 bouts of 4 min at 90–95% of peak power interspersed by 3 min at 45% of peak power	↔ leucocyte count; ↑ lymphocyte count immediately after exercise followed by ↓ 30 min, 60 min and 180 min after exercise; ↑ neutrophil count 60 min and 180 min after exercise; ↔ mixed cell count
			Cycling SIT—4 bouts of 30 s “all-out” effort interspersed by 7.5 min passive recovery	↑ leucocyte count immediately, and 180 min after exercise; ↑ lymphocyte count immediately after exercise followed by ↓ 60 min and 180 min after exercise; ↑ neutrophil count 60 min and 180 min after exercise; ↑ mixed cell count immediately after exercise
			Cycling SIT—4 bouts of 30 s “all-out” effort interspersed by 7.5 min at 45% of peak power	↑ leucocyte count immediately, and 180 min after exercise; ↑ lymphocyte count immediately after exercise followed by ↓ 30 min, 60 min, and 180 min after exercise; ↑ neutrophil count 60 min, and 180 min after exercise; ↔ mixed cell count
De Oliveira Ottone et al. 2019 [25]	12 inactive health men (age: 22.5 ± 3.9 years)	Clinical trial	Cycling HIIT—8 bouts of 60 s at 90% peak power interspersed by 75 s of active recovery (30 watts)	↓ neutrophil oxidative burst in response to f-PMN 30 min after exercise; ↑ neutrophil phagocytic capacity, oxidative burst and redox status 24 h after exercise
Jamurtas et al. 2018 [45]	12 health men (age: 22.4 ± 0.5 years)	Randomized cross-over trial	Cycling SIT—4 bouts of 30 s “all-out” effort interspersed by 4 min of active recovery	↑ leucocyte count immediately after exercise
Souza et al. 2018 [46]	10 obese men (age: 28.5 ± 2.7 years)	Randomized cross-over trial	Running HIIT—10 bouts of 1 min at 90% of V_max interspersed by 1 min at 30% of V_max	↔ secretory IgA and IgA concentration
Rodrigues de Araujo et al. 2018 [47]	32 men soccer players (age: 21.2 ± 4.2 years)	Clinical trial	Running SIT—7 bouts of 40 m “all-out” effort with direction changes interspersed by 25 s of active recovery (light jogging)	↔ IgA concentration
Belviranli et al. 2017 [48]	10 inactive health men (age: 20.0 ± 1.33 years)	Clinical trial	Cycling SIT—4 bouts of 30 s “all-out” effort interspersed by 4 min of active recovery (the load was determined according with the Monark Anaerobic Test Software)	↑ leucocyte count immediately, 3h, and 6 h after exercise; ↑ lymphocyte count immediately after exercise followed by ↓ lymphocyte count 3 h, and 6 h after exercise; ↑ neutrophil count 3 h, and 6 h after exercise; ↔ monocyte count; ↑ eosinophil count immediately after exercise followed by ↓ 3 h, and 6 h after exercise; ↑ basophil count immediately after exercise
Krüger et al. 2016 [49]	23 untrained health men (age: 25.7 ± 3.2 years)	Randomized cross-over trial	Cycling HIIT—5 bouts of 3 min at 90% peak power output interspersed by 3 min of active recovery (without resistance)	↑ lymphocyte CD3+, CD4+ and CD8+ count immediately, and 3 h after exercise; ↑ mobilization of low differentiated T cells, regulatory T cells and progenitor cells; ↑ apoptosis in high differentiated T cells
Tossige-Gomes et al. 2016 [26]	10 inactive health men (age: 23.7 ± 1.1)	Clinical trial	Cycling HIIT—8 bouts of 1 min at 100% of peak power interspersed by 75 s of active recovery at 30 W	↑ lymphocyte redox imbalance 30 min after exercise; ↓ lymphocyte proliferation in response to antigenic, but not to mitogenic stimulation immediately and 30 min after exercise
	6 inactive health men (age: 21.3 ± 1.8 years)		Cycling HIIT—8 bouts of 1 min at 100% of peak power interspersed by 75 s of active recovery at 30 W	↔ lymphocyte viability
Turner et al. 2016 [50]	9 health men (age: 22.1 ± 3.4 years)	Randomized cross-over trial	Cycling HIIT—10 bouts of 1 min at 90% of $\dot{V}$ O_2max interspersed by 1 min at 40% of $\dot{V}$ O_2max	↑ leucocyte, lymphocyte count immediately after exercise; mobilization of cutaneous lymphocyte natural killer and lymphocyte CD8+ to blood
Dorneles et al. 2016 [51]	12 overweight-obese men (age: 27.41 ± 9.20 years)	Randomized cross-over trial	Running HIIT—10 bouts of 1 min at 85–90% maximum power output interspersed by 75 s at 50% maximum power output	↑ leucocyte, lymphocyte, and monocyte count immediately after exercise
	10 lean men (age: 26.5 ± 6.11 years)		Running HIIT—10 bouts of 1 min at 85–90% maximum power output interspersed by 75 s at 50% maximum power output	↑ leucocyte immediately and 30 min after exercise; ↑lymphocyte and monocyte immediately after exercise
Arroyo-Morales et al. 2012 [52]	50 active health subjects, 25 men (age: 22.4 ± 3.42 years)	Clinical trial	Arm-cycling SIT—3 bouts of 30 s “all-out” effort interspersed by 3 min (90 s of active recovery at 50% W work rate and 90 s of passive recovery)	↔ secretory IgA
Friedman et al. 2012 [53]	8 health subjects, 4 men (age: 24)	Clinical trial	SIT—2 sets of 3 bouts of 30 s “all-out” effort interspersed by 2 min of active recovery. Sets were separated by 6.75 min	↑ lymphocyte CD8+, and CD8+/CD45RA+ count and ↑ lymphocyte CD8+, and CD8+/CD45RA+ migration immediately after exercise. ↑ lymphocyte CD8+, and CD8+/CD45RA+ count and ↔ lymphocyte CD4+, and CD4+/CD45RA+ migration immediately after exercise
Fisher et al. 2011 [27]	8 active health men (age: 22 ± 2 years)	Clinical trial	Cycling HIIT—4 bouts with 30 s at 90% of maximum anaerobic power interspersed by 4 min of active recovery at 15% of maximum anaerobic power	↑ leucocyte and neutrophil counts immediately and 3 h after exercise; ↑ lymphocyte count immediately after exercise; ↓ lymphocyte cell viability 3 h after exercise
Davison 2011 [24]	9 active health men (age: 27 ± 5 years)	Randomized cross-over trial	Cycling SIT—4 bouts of 30 s “all-out” effort interspersed by 4 min of active recovery with light loads	↔ secretory IgA and ↑ IgA concentration; ↑ neutrophil count immediately and 30 min after exercise; ↓ neutrophil oxidative burst in response to fMLP 30 min after exercise
Thomas et al. 2010 [54]	10 health adolescent women (age 15.5 ± 0.6 years)	Clinical trial	Cycling SIT—8 bouts of 8 s “all-out” effort interspersed by 30 s of passive recovery	↔ IgA concentration 5 min after exercise
Fahlman et al. 2001 [22]	26 active health women (age: 24.2 ± 5.8 years)	Clinical trial	Cycling SIT—3 bouts of 30 s “all out” effort interspersed by 3 min (90 s of active recovery pedaling against light load and 90 s of passive recovery)	↓ secretory IgA and ↔ IgA concentration 5 min after exercise
Walsh 1999 [55]	8 trained men (age: 25 ± 1 years)	Clinical trial	Cycling HIIT –20 bouts of 1 min at 100% of $\dot{V}$ O_2max interspersed by 2 min at 30% of $\dot{V}$ O_2max	↔ secretory IgA and IgA concentration after exercise
Walsh et al. 1998 [56]	8 trained men (age: 25 ± 3 years)	Clinical trial	Cycling HIIT—20 bouts of 1 min at 100% of $\dot{V}$ O_2max interspersed by 2 min at 30% of $\dot{V}$ O_2max	↑ leucocytes and neutrophil count 5 min, 1 h, 2.5 h, and 5 h after exercise; ↑ lymphocyte count immediately after exercise followed by ↓ 1 h after exercise
Hinton et al. 1997 [57]	5 men runners (age: 23.0 ± 2.5 years)	Clinical trial	Running HIIT—15 bouts of 1 min at 90% of $\dot{V}$ O_2max interspersed by 2 min of passive recovery	↓ lymphocyte function immediately after exercise
Kargotich et al. 1997 [58]	8 high performance men swimmers (age: 19.9 ± 2.2 years)	Clinical trial	Swimming HIIT—15 bouts of 100 m freestyle swimming interspersed by 2 min 25 m recovery swim	↑ leucocyte and neutrophil count immediately after exercise; ↑ lymphocyte count immediately after exercise followed by ↓ 1 h, 2 h, and 2.5 h after exercise; ↑ monocyte count immediately and 30 min after exercise; ↔ eosinophil count
Gray et al. 1993 [59]	8 men triathletes (age: 31.5 ± 4.5 years)	Clinical trial	Running HIIT—1 min at 100% of v $\dot{V}$ O_2max interspersed by 1 min of active recovery until the exhaustion	↑ leucocyte and lymphocyte count immediately after exercise; ↑ granulocyte and monocyte count 6 h after exercise
Mackinnon & Jerkin, 1993 [23]	12 active health men (age: 17 to 25 years)	Clinical trial	Cycling SIT—5 bouts of 1 min “all out” effort interspersed by 5 min of passive recovery	↓ secretory IgA and ↑ IgA concentration immediately after exercise
Fry et al. 1992 [60]	14 men runners (age: 18–25 years)	Clinical trial	Running Treadmill HIIT—25 bouts of 1 min at one stage before that which the subject failed in the preliminary test) followed by 2 min active recovery	↓ lymphocyte proliferative response immediately after exercise
	18 men kayakists (age: 18–25 years)		Paddling HIIT—25 bouts of 1 min at one stage before that which the subject failed in the preliminary test interspersed by 2 min of active recovery	↓ lymphocyte proliferative response immediately after exercise
Fry et al. 1992 [61]	7 men runners (age: 22.9 ± 5.6 years)	Cross-over clinical trial	Running HIIT—15 bouts of 1 min at 90% of V_max interspersed by 2 min of active recovery	↔ leucocytes, lymphocyte, neutrophil and monocyte count 5 min after exercise. ↔ the CD4⁺:CD8⁺ ratio and responsiveness of T cells to T cells mitogens
			Running HIIT—15 bouts of 1 min at 120% of V_max interspersed by 2 min of active recovery	↑ leucocytes count, lymphocyte, neutrophil, monocyte count 5 min after exercise. ↓ the CD4⁺:CD8⁺ ratio and responsiveness of T cells to mitogens immediately after exercise

HIIT, high intensity interval training; SIT, sprint interval training; IgA, immunoglobulin A; $\dot{V}$ O_2max, maximal oxygen consumption; $\dot{V}$ O₂max, velocity associated to maximal oxygen consumption; V_max, maximal velocity achieved during the incremental test. fMLP, formyl-leucyl-methionyl-phenylalanine. ↑ significant increase; ↓ significant decrease; ↔ no significant change.