Table 1 Meta-analysis inclusion and exclusion criteria

1

Original research published in peer-reviewed journal

Excluded non-investigation studies such as reviews, book chapters, abstracts, theses, opinion piece, surveys, letters to editor, etc.

2

Studies published until January 2022

In accordance with our most updated searches, studies published from the inception up until January 2022 were considered for inclusion, including studies published in the Epub ahead of print format

3

Available in English language

Full text is in English

4

Population

Team sport athletes with no restriction of age, level and sex

5

Study design

Test–retest designs

Studies examining the reliability of SMFT HRex in controlled settings (e.g., scheduling, training context) and reporting absolute (group mean difference [MD], typical error of measurement [TE]), relative (intraclass correlation coefficient [ICC]) effect estimates, or both

Correlational designs

Studies examining the convergent validity of SMFT HRex with reference to a maximal endurance performance test and reporting correlational statistic (correlation coefficient [r]) of this relationship

6

Settings

SMFT were administered either in laboratory, indoor/outdoor field-based formats or combination of two

7

SMFT

Any SMFT including cycling, running, or standardised drills and games (refer to Fig. 2, ‘SMFT protocol categories’)

Intensity

Excluded prolonged ‘all-out’ maximal intensities, intensities that cause a voluntary cessation, and intensities that elicit excessive training stimulus beyond that originally intended (for more details refer to a previously published review [8]; ‘Submaximal Fitness Tests Definition’)

Duration

The duration was ≤ 15 min of exercise for all SMFT, while exercise refers to the time when HRex was monitored. Therefore, the duration of rest intervals was excluded (for example, recovery between sets)

8

Outcome Measure

HRex (expressed as %HR_max)