Table 1 Variables to be extracted at the full-text stage

Bibliographic

• Authors

• Title

• Year of publication

• Journal

• Sources of funding

• Institutions and affiliations

• Reported conflict of interest

• Study design

• Country

• Setting(s)

• Type of allocation sequence

• Inclusion and exclusion criteria outlined by the study

Demographics

• Age

• Sex

• Sample size

• Description of health status

• Physical activity levels

• Fitness levels

Exercise protocol

• Warm-up and cool-down duration, intensity, and modality

• Exercise modality (e.g., treadmill, stationary cycle)

• Number and duration of work/recovery intervals

• Exercise intensity

• Exercise session volume (total time of work and recovery intervals)

Blood lactate outcomes

• Time difference between exercise termination and blood procurement

• Method of blood draw (e.g., finger prick, earlobe prick, or blood draw from limbs)

• Baseline and post-exercise blood lactate levels (mmol/L) with standard deviations

Cognitive performance outcomes

• Time difference between exercise termination and cognitive assessment

• Cognitive tests and domain

• Baseline and post-exercise cognitive scores with standard deviations

Additional variables

• Peak oxygen uptake peak heart rate, and work rate from graded exercise test

• Average heart rate, work rate, and oxygen uptake during HIIT/SIT

• Adverse effects (e.g., reasons for dropout, dizziness)

• Recruitment, retention, adherence, outcome rates and acceptability of intervention