Table 2.

Summary of the Participants and Intervention Characteristics of the Studies which Investigated the Acute Effects of Hip Flexor Stretching on Performance.

Study	Population			Stretching Intervention
	Subjects (m/f)	n	Age (Years)	Stretching Type	Stretching Method	Stretching Duration (Total Time)	Stretching Intensity
Aslan et al. [12]	m/f	36 (25/11)	22.37 ± 1.63	PNF (hold-relax)	6 × 20 s [10 s rest]	2 min/leg	<POD
				Dynamic	6 × 10 reps [10 s rest]	2 min/leg	<POD
Cramer et al. [21]	m/f	21 (7/14)	21.5 ± 1.3	Static	Unassisted: 4 × 30 s [20 s rest] + 3 × assisted: 4 × 30 s [20 s rest]	8 min/leg	POMD
Cramer et al. [22]	m/f	18 (8/10)	21.4 ± 3.0/23.0 ± 2.9	Static	Unassisted: 4 × 30 s [20 s rest] + 3 × assisted: 4 × 30 s [20 s rest]	8 min/leg	POMD
Marek et al. [24]	m/f	19 (9/10)	21 ±3/23 ± 3	Static	Unassisted: 4 × 30 s [20 s rest] + 3 × assisted: 4 × 30 s [20 s rest]	8 min/leg	POD
				PNF (contract-relax)	Unassisted: 4 × 30 s [20 s rest] + 3 × assisted: 4 × 30 s [20 s rest]	8 min/leg	POD
Wakefield et al. [25]	m	15	24.1 ± 2.4	Static	Assisted: 3 × 30 s [30 s rest]	90 s/leg	POMD
Wallmann et al. [23]	m/f	25 (16/9)	26.76 ± 2.42	Static	2 × 30 s	30 s/leg	<POD
				Dynamic	4 × 15 s	30 s/leg	<POD
				Ballistic	4 × 15 s	30 s/leg	<POD
Young et al. [26]	m	16	18–33	Static	2 × assisted: 6 × 30 s [30 s rest] + unassisted: 6 × 30 s [30 s rest]	4.5 min/leg	<POD
Zakas et al. [27]	m	15	25 ± 1.5	Static	Unassisted: 4 × 15 s [15 s rest]	1 min/leg	<POD
					Unassisted: 4 × 15 s [15 s rest] + assisted: 28 × 15 s [15 s rest]	8 min/leg	<POD

POD = point of discomfort, POMD = point of mild discomfort.