Table 2.

Selection criteria for muscular strength studies, running speed studies and running endurance studies

Category	Inclusion criteria	Exclusion criteria
Population	Healthy male and female athletes (defined as participants who engaged in organized sports training and competition) with a mean age ≥ 18 years	Older adults (65 and over), disabled athletes, injured athletes
Intervention	Training program needed to last for a minimum of 4 weeks (or 12 training sessions) with at least 2 sessions per week Resistance training interventions including free weights, machine weights, isokinetic devices, elastic bands, resisted running and plyometrics	Combined interventions containing no resistance exercises (e.g. sprint or endurance running, balance exercises) or nutritional, pharmacological, physiological and psychological aids
Comparator	No restriction
Outcome	Studies that tested maximum strength performance (in kg or Ib) or maximum running speed performance distance or maximum running endurance performance (in units of time) as a dependent variable	Athletic performance was tested by isokinetic condition, VO2max, power measurements (e.g. in Watts), and jumping tests
Study design	Randomised and non-randomised controlled trials	Systematic reviews, cohort studies, case-control studies, cross sectional studies