Table 1 Description of included studies

Abdel-Aziem & Mohammad [38]

N = 75. IG1 (untrained group): n = 25. IG2 (trained group): n = 25. CG: n = 25.

Plantar flexors

Stretching was performed by staying 2 to 3 feet from a wall and moving the right foot from the wall until participant felt a stretching in the posterior chain of the calf muscle. The hands had to be placed against the wall, and extend the right hip and the right knee

placing their hands against the wall and

maintaining their right hip and knee in extension

Maximal concentric torque in the Plantar flexion with 30°/s (in NM)

Pre-test IG1: 82.28 ± 15.46, Post-test: IG1 89.80 ± 14.31

Pre-test IG2: 80.16 ± 14.57, Post-test: IG2 80.04 ± 14.22

Pre-test CG: 78.76 ± 13.36, Post-test: CG 78.84 ± 13.16

Maximal concentric torque in the Plantar flexion with 120°/s (in NM)

Pre-test IG1: 55.04 ± 10.77, Post-test IG1: 61.35 ± 9.78

Pre-test IG2: 50.96 ± 7.64, Post-test IG2: 58.42 ± 7.64

Pre-test CG: 49.75 ± 6.94, Post-test CG: 50.00 ± 6.94

Maximal eccentric torque in the Plantar flexion with 30°/s (in NM)

Pre-test IG1: 85.61 ± 14.99, Post-test IG1: 95.81 ± 12.58

Pre-test IG2: 81.08 ± 12.98, Post-test IG2: 90.79 ± 14.03

Pre-test CG: 80.16 ± 13.61, Post-test CG: 81.04 ± 13.84

Maximal eccentric torque in the Plantar flexion with 120°/s (in NM)

Pre-test IG1: 92.52 ± 10.74, Post-test IG1: 104.09 ± 10.45

Pre-test IG2: 88.47 ± 9.64, Post-test IG2: 96.84 ± 11.95

Pre-test CG: 87.58 ± 15.21, Post-test CG: 87.96 ± 15.17

Akagi & Takahashi [39]

N = 19, right and left leg

Plantar flexors

3 × 2 min stretching with one minute rest in between on 6 days per week for 5 weeks by using a stretching board, stretching was performed without pain and discomfort

Muscle thickness in the plantar flexors (in mm)

Pre-test IG: 7.6 ± 0.8, Post-test IG: 7.6 ± 0.7

Pre-test CG: 7.6 ± 0.7, Post-test CG: 7.6 ± 0.7

Maximal Joint torque (in Nm)

Pre-test IG: 118 ± 25, Post-test IG: 121 ± 20

Pre-test CG: 116 ± 21, Post-test CG: 119 ± 17

Andrade et al. [66]

N = 39. IG: n = 21. CG: n = 18.

Plantar flexors

2 static stretching exercises each performed 5 × 45 s per session, 5 sessions per week for 12 weeks.

Muscle thickness in gastrocnemius medialis (in mm)

Pre-test IG: 1.6 ± 0.3, Post-test IG: 1.7 ± 0.2

Pre-test CG: 1.5 ± 0.2, Post-test IG: 1.6 ± 0.1

Muscle thickness in gastrocnemius lateralis (in mm)

Pre-test IG: 1.3 ± 0.2, Post-test IG: 1.3 ± 0.2

Pre-test CG: 1.4 ± 0.2, Post-test IG: 1.3 ± 0.1

Barbosa et al. [40]

N = 45. IG1 (static stretching): n = 15. IG2 (dynamic stretching): n = 15. CG: n = 15.

Hamstrings

Stretching was performed 3 times per week until 10 sessions are completed, static stretching with 3 × 30 s, dynamic stretching 3 × 30 repetitions.

Static stretching was performed from a supine position via hip flexion with extended knee joint until point of discomfort

Maximal eccentric peak torque (in Nm/kg)

Pre-test IG 250.58 ± 37.54, Post-test IG 211.95 ± 46.45

Pre-test CG 238.71 ± 42.10, Post-test CG 229.43 ± 41.10

Brusco et al. [41]

N = 13. Contralateral leg as control condition.

Hamstrings

Stretching was performed with eight repetitions of 60 s each on two non-consecutive days per week for six weeks.

Dynamic torque (in Nm)

Pre-test IG: 110.2 ± 19.4, Post-test IG: 106.3 ± 18.1

Pre-test CG: 107.2 ± 11.4, Post-test CG: 100.1 ± 20.6

Caldwell et al. [42]

N = 30. IG1 (stretching 1x /day): n = 10. IG2 (stretching 2x /day): n = 10. CG: n = 10.

Hamstrings & Quadriceps

3 × 30 s stretching training with 15 s rest between each set for 2 weeks. Stretching was performed daily or twice daily

Maximal strength in the hamstrings

Pre-test IG 1x per day: 109.1 ± 11.9, Post-test IG 1x per day: 118.5 ± 12.9

Pre-test IG 2x per day: 110.5 ± 9.6, Post-test IG 2x per day: 111.5 ± 13.1

Pre-test CG: 110.8 ± 17.4, Post-test CG: 110.5 ± 17.6

Maximal strength in the Quadriceps

Pre-test IG 1x per day: 438.7 ± 91.8, Post-test IG 1x per day: 445.2 ± 78.4

Pre-test IG 2x per day: 546.5 ± 46.9, Post-test IG 2x per day: 585.3 ± 48.3

Pre-test CG: 492.9 ± 99.4, Post-test CG: 472.5 ± 87.2

Chen et al. [43]

N = 30, three groups, CG, n = 10, stretching group, n = 10, PNF group, n = 10

Hamstrings

Unilateral hamstring stretch with support of the investigator to reach point of discomfort. Stretching was performed 30 × 30 s 3x per week for 8 weeks

MVC in the knee flexion (in Nm)

Pre-test IG 72.7 ± 3.2, Post-test IG 79.0 ± 3.0

Pre-test CG 70.4 ± 3.9, Post-test CG 71.0 ± 4.0

MVC in the knee extension (in Nm)

Pre-test IG 124.9 ± 7.8, Post-test IG 128.7 ± 8.3

Pre-test CG 117.1 ± 6.7, Post-test CG 119.3 ± 6.8

Cini et al. [44]

N = 12. IG: n = 6. CG: n = 6.

Hamstrings

1 × 30 s hamstring stretch per session, three sessions per week for 4 weeks.

Knee flexion peak torque (in Nm)

Pre-test IG: 66 ± 14.4, Post-test IG: 70.2 ± 8.4

Pre-test CG: 70.2 ± 12, Post-test CG: 73.2 ± 15

Freitas & Mil-Homens [67]

N = 10, IG n = 5, CG n = 5

Hamstrings

1 × 450 s of continuous stretching with highest tolerable torque with was ensured by increasing ROM every 90 s to new maximal ROM. Stretching was performed 5 days per week for 8 weeks.

Muscle thickness of biceps femoris long head (in mm)

Pre-test IG: 145.4 ± 6.9, Post-test IG: 142.9 ± 8.8

Pre-test CG: 143.4 ± 15.2, Post-test CG: 141.9 ± 15.5

Ikeda & Ryushi [45],

N = 25. IG: n = 12. CG: n = 13

Knee extensors

6 × 30 s stretching of the quadriceps/knee extensors with a rest of 60 s in between 3 days per week for 6 weeks

Maximal strength (in N)

Pre-test IG 4182 ± 958, Post-test IG 4607 ± 1015

Pre-test CG 3732 ± 714, Post-test CG 3725 ± 754

Kay et al. [68]

N = 26. IG: n = 13. CG: n = 13.

Knee extensors

5 sets of 12 × 3 s stretch on maximally contracted knee flexors induced by isokinetic dynamometer. 2 sessions per week for 6 weeks.

Vastus lateralis thickness (in mm)

Pre-test IG: 27.3 ± 1.1, Post-test IG: 29.3 ± 1.1

Pre-test CG: 26.4 ± 1.3, Post-test CG: 26.4 ± 1.3

Kokkonen et al. [46]

N = 38. IG: n = 19. CG: n = 19.

Lower extremities

Stretching was performed 40 min per session 3x per week for 10 weeks including 15 exercises for the major muscle groups of the lower extremity. Each exercise was performed 3 × 15 s

1RM in the knee flexion (in kg)

Pre-test IG 44.7 ± 14.5, Post-test IG 51.0 ± 14.1

Pre-test CG 46.1 ± 15.1, Post-test CG 47.0 ± 14.4

1RM in the Knee extension (in kg)

Pre-test IG 63.8 ± 24.5, Post-test IG 82.0 ± 25.8

Pre-test CG 69.7 ± 21.5, Post-test CG 71.0 ± 20.8

Konrad & Tilp [47],

N = 41, IG: n = 21. CG: n = 20.

Plantar flexors

Stretching both plantar flexors unilateral in a standing wall push position until point of discomfort. Stretching was performed five times per week for six weeks with four times 30 s each session. The stretching was done alternating both legs with no rest in-between.

Maximal voluntary contraction torque (in Nm)

Pre-test IG: 96.88 ± 35.8, Post-test IG: 100.4 ± 39.6

Pre-test CG: 92.7 ± 29.3, Post-test CG: 90.1 ± 33.2

Kubo et al. [48]

N = 8. Contralateral leg as control condition.

Plantar flexors

5 × 45 s unilateral static stretch, 2x per day for 20 consecutive days.

Maximal voluntary contraction torque (in Nm)

Pre-test IG: 131 ± 17, Post-test IG: 132 ± 20

Pre-test CG: 130 ± 19, Post-test CG: 128 ± 18

LaRoche et al. [49]

N = 19. IG: n = 9. CG: n = 10.

Hamstrings

10 × 30 s static stretch per session, 3 sessions per week for 4 weeks.

Knee flexion peak torque (in Nm)

Pre-test IG: 239.5 ± 49, Post-test IG: 257.5 ± 58.2

Pre-test CG: 278.8 ± 68.2, Post-test CG: 289.5 ± 55.4

Leslie et al. [50]

N = 16. IG: n = 8. CG: n = 8.

Hamstrings

Unilateral static stretching of both legs, 15 min per session, 3 sessions per week for 4 weeks.

Knee flexion eccentric peak torque (in Nm)

Pre-test IG: 107.3 ± 28.4, Post-test IG: 113.3 ± 34.6

Pre-test CG: 99.5 ± 30.2, Post-test CG: 100.6 ± 30.5

Knee flexion isometric peak torque (in Nm)

Pre-test IG: 93.4 ± 23.6, Post-test IG: 95 ± 30.1

Pre-test CG: 81.6 ± 21.9, Post-test CG: 84.6 ± 22

Knee flexion concentric peak torque (in Nm)

Pre-test IG: 87.9 ± 21.8, Post-test IG: 92.6 ± 28.1

Pre-test CG: 81.5 ± 25.2, Post-test CG: 80 ± 22.9

Lima et al. [51]

N = 24. IG: n = 12. CG: n = 12.

Knee flexors & extensors

Unilateral 3 × 30 s static stretch per session for knee flexors and extensors each, 3 sessions per week for 8 weeks.

Knee extension isometric peak torque (in Nm)

Pre-test IG: 218.1 ± 47.23, Post-test IG: 218.33 ± 40.80

Pre-test CG: 204.9 ± 4.79, Post-test CG: 211.2 ± 27.17

Knee flexion isometric peak torque (in Nm)

Pre-test IG: 114.66 ± 27.18, Post-test IG: 122.25 ± 21.82

Pre-test CG: 120.54 ± 22.08, Post-test CG: 117.09 ± 22.42

Vastus lateralis muscle thickness (in mm)

Pre-test IG:27.98 ± 6.67, Post-test IG: 26.192 ± 3.97

Pre-test CG: 24.58 ± 4.36, Post-test CG: 23.77 ± 3.97

Biceps femoris muscle thickness (in mm)

Pre-test IG: 25.32 ± 4.87, Post-test IG: 25.99 ± 3.33

Pre-test CG: 22.65 ± 4.01, Post-test CG: 23.46 ± 3.55

Longo et al. [52]

N = 30, IG n = 15 CG n = 15

Plantar flexors

Stretching was performed 5 × 45 s with a rest of 15 s by using two exercises, 5x per week for 6 and 12 weeks, 450 s stretching duration per session. For the first exercise, a stretching board was used, for the second exercise a gymnastic band was used for stretching the plantar flexors with flexed hip and extended knee joint. Stretching was performed to the maximal point of discomfort

Maximal strength in the plantar flexion (in Nm)

Pre-test IG 147.2 ± 32.1

6w Post-test IG 148.7 ± 32.4

12w Post-test IG 150.4 ± 32.6

Pre-test CG 151.7 ± 33.7

6w Post-test CG 152.8 ± 32.8

12w Post-test CG 153.9 ± 38.1

Muscle thickness in the medial head of the gastrocnemius (in mm)

Pre-test IG 20.11 ± 2.38

6w Post-test IG 20.52 ± 2.55

12w Post-test IG 20.08 ± 1.80

Pre-test CG19.33 ± 2.46

6w Post-test CG 19.21 ± 2.13

12w Post-test CG 19.20 ± 2.24

Muscle thickness in the lateral head of the gastrocnemius (in mm)

Pre-test IG 16.11 ± 2.65

6w Post-test IG 16.20 ± 2.99

12w Post-test IG 17.05 ± 2.32

Pre-test CG 15.07 ± 2.63

6w Post-test CG 15.13 ± 2.69

12w Post-test CG 15.06 ± 2.55

Muscle thickness in the soleus (in mm)

Pre-test IG 15.17 ± 2.78

6w Post-test IG 15.45 ± 3.03

12w Post-test IG 15.28 ± 2.93

Pre-test CG 14.77 ± 3.89

6w Post-test CG 15.06 ± 4.19

12w Post-test CG 14.76 ± 4.22

Marshall et al. [53]

N = 22

IG = 11,

CG = 11

Hamstrings

4 passive stretching exercises for the hamstrings were performed 5 times per week for 4 weeks. 1 session per week was supervised. Each stretch was performed 3 × 30 s.

Hamstring strength 30°s^− 1in Nm

Pre-test IG 49.7 ± 16.2, Post-test IG 50.8 ± 20.2

Pre-test CG 42.6 ± 10.8, Post-test CG 46.1 ± 13.9

Hamstring strength 120°s^− 1 in Nm

Pre-test IG 43.5 ± 12.8, Post-test 46.1 ± 12.1

Pre-test CG 48.7 ± 15.1, Post-test 49.3 ± 17.1

Minshull et al. [54]

N = 9. Contralateral leg as control condition.

Knee flexors

4 × 10 s stretch per sessoion, 3 sessions per week for 8 weeks.

Knee flexion peak force (in N)

Pre-test IG: 329 ± 77, Post-test IG: 325 ± 75

Pre-test CG: 321 ± 64, Post-test CG: 317 ± 69

Mizuno [55]

N = 20, IG = 11, CG = 9

Plantar flexors

SS + ES = 4 sets of 30 s stretch with 30 s rest in-between sets, 3 times per week for 8 weeks, electrical stimulation with 80 Hz. Intensity with maximal mA without pain Calf muscle stretch performed with a stretching board. Weekly volume: 6 min.

SS = only 4 × 30 s of static stretching with a stretching board, 3 times per week for 8 weeks.

Maximal strength in the plantar flexion (in N)

Pre-test IG 454 ± 198, Post-test IG 562 ± 259

Pre-test IG (SS) 460 ± 104, Post-test IG (SS) 537 ± 110

Pre-test CG 465 ± 152, Post-test CG 485 ± 153

Morton et al. [56]

N = 24. IG: n = 12. CG: n = 12.

Full body

Participants stretched the pectoralis, deltoid, gluteus, adductors, hamstrings and quadriceps. Stretching was performed three times per week for five weeks. Total stretch time was 510 s per session.

Knee extension peak torque at 180°⁻¹(in Nm)

Pre-test IG: 88.38 ± 23.30, Post-test IG: 91.36 ± 25.21

Pre-test CG: 98.66 ± 24.51, Post-test CG: 95.86 ± 25.38

Knee flexion peak torque at 180°⁻¹(in Nm)

Pre-test IG: 44.29 ± 12.17, Post-test IG: 45.10 ± 11.06

Pre-test CG: 48.21 ± 10.89, Post-test CG: 50.46 ± 13.01

Moltubakk et al. [57]

N = 26

Plantar flexors

24 weeks, daily stretching 4 × 60 s, self administered with straight and bent knee joint by using a visual analog scale (VAS-scale)

Muscle thickness in the medial head of the gastrocnemius (in mm)

Pre-test IG 19.7 ± 2.1, Post-test IG21.2 ± 2.0

Pre-test CG 19.8 ± 2.3, Post-test CG 21.7 ± 2.7

Nakamura et al. [58]

N = 40, IG1 high intensity stretching n = 14, IG2 low intensity n = 13, CG n = 13

Plantar flexors

3 × 60 s stretch of the plantar flexors for 4 weeks 3x per week using a stretching board, intensity was documented via 11-point verbal numerical scale, 0 = no pain at all, 10 = very, very painful

Maximal isometric strength in the plantar flexors at 30° plantar flexion (in Nm)

Pre-test IG1 52.5 ± 20.1, Post-test IG1 55.9 ± 17.6

Pre-test IG2 54.8 ± 50.4, Post-test IG2 50.4 ± 20.0

Pre-test CG 61.4 ± 15.9, Post-test CG 64.1 ± 16.3

Maximal isometric strength in the plantar flexors at neutral position (in Nm)

Pre-test IG1 146.9 ± 30.2, Post-test IG1 148.1 ± 22.0

Pre-test IG2 146.6 ± 27.1, Post-testIG2 148.8 ± 28.9

Pre-test CG 170.8 ± 24.0, Post-test CG 171.1 ± 19.4

Maximal isometric strength in the plantar flexors at 15° dorsiflexion (in Nm)

Pre-test IG1 193.2 ± 43.6, Post-test IG1 198.4 ± 29.2

Pre-test IG2 191.0 ± 37.6, Post-test IG2 189.1 ± 42.9

Pre-test CG 191.4 ± 40.7, Post-test CG 193.5 ± 45

Maximal dynamic strength with 30°/s (in Nm)

Pre-test IG1 115.2 ± 32.2, Post-test IG1 120.4 ± 21.9

Pre-test IG2 116.8 ± 22.8, Post-test IG2 120.0 ± 26.4

Pre-test CG 131.7 ± 17.3, Post-test CG 135.5 ± 15.2

Maximal dynamic strength with 120°/s (in Nm)

Pre-test IG1 73.6 ± 16.2, Post-test IG1 74.5 ± 15.0

Pre-test IG2 74.2 ± 17.6, Post-test IG2 72.7 ± 20.0

Pre-test CG 68.2 ± 18.3, Post-test CG 69.7 ± 18.5

Muscle thickness gastrocnemius medialis in mm

Pre-test IG1 19.2±2.9, Post-test IG1 19.5±2.5

Pre-test IG2 20.7±2.5, Post-test IG2 20.5±2.8

Pre-test CG 19.7±3.0, Post-test CG 19.4±2.7

Muscle thickness gastrocnemius lateralis in mm

Pre-test IG1 15.8±2.4, Post-test IG1 15.5±2.4

Pre-test IG2 18.3±1.8, Post-test IG2 17.5±2.1

Pre-test CG 17.5±2.6, Post-test CG 17.5±2.5

Muscle thickness soleus in mm

Pre-test IG1 17.7±3.1, Post-test IG1 17.4±3.3

Pre-test IG2 19.4±2.8, Post-test IG2 19.4±3.1

Pre-test CG 19.6±3.4, Post-test CG 19.7±2.6

Nakao et al. [59]

N = 30, IG = 15 CG = 15

Hamstrings

5 min stretching of the hamstring muscle 3x per week for 4 weeks, knee was extended passively until the point before discomfort

Isokinetic strength 60°/s (in Nm)

Pre-test IG 77.7 ± 15.3, Post-test IG 85.9 ± 18.8

Pre-test CG 73.4 ± 17.6, Post-test CG 74.2 ± 14.2

Isokinetic strength 180°/s (in Nm)

Pre-test IG 58.8 ± 15.8, Post-test IG 66.8 ± 14.6

Pre-test CG 58.6 ± 16, Post-test CG 59.6 ± 11.7

Isometric strength (in Nm)

Pre-test IG 106.0 ± 22.1, Post-test IG 103.2 ± 19.8

Prestest CG 95.9 ± 20.2, Post-test CG 95.5 ± 16.1

Nelson et al. [60]

N = 25, IG = 13, CG = 12

Plantar flexors

10 weeks static stretching of the plantar flexors, 4 × 30 s stretching with 30 s rest by staying with the ball of the foot on a beam and let the beam hanging unsupported over the edge of the beam, participant should place the bodyweight on the right leg to improve stretching stimulus

Maximal strength measurement (in N)

Pre-test IG 356 ± 76, Post-test IG 456 ± 85

Pre-test CG 369 ± 51, Post-test CG 368 ± 52

Nobrega et al. [61]

N = 21. IG: n = 11. CG: n = 10.

Full body

40 min stretching sessions, 2 sessions per week for 12 weeks.

Right handgrip strength (in kg)

Pre-test IG: 33.7 ± 3.3, Post-test IG: 35.5 ± 3.2

Pre-test CG: 43.1 ± 3.9, Post-test CG: 42.6 ± 3.9

Left handgrip strength (in kg)

Pre-test IG: 34.1 ± 3.1, Post-test IG: 35.9 ± 2.9

Pre-test CG: 37.8 ± 3.2, Post-test CG: 38.6 ± 3.3

1RM Benchpress (in kg)

Pre-test IG: 30.2 ± 5.2, Post-test IG: 31.1 ± 5.3

Pre-test CG: 37 ± 6.5, Post-test CG: 34 ± 5.7

1RM Leg press (in kg)

Pre-test IG: 85.6 ± 10.5, Post-test IG: 111.3 ± 14.6

Pre-test CG: 94.8 ± 8.2, Post-test CG: 105.3 ± 10.6

Panidi et al. [69]

N = 12. Contralateral leg as control condition.

Plantar flexors

Female volleyball athletes performed five stretch sessions per weeks for 12 weeks. Stretch sessions consisted of two sets of six static plantar flexor stretches using a stretching board. Each repetition lasted 45 s in week 1. Stretching time per repetition was increased by 15 s every 3 weeks, apart from the last 3 weeks. Total stretching duration thus increased from 540 s to 900 s.

Gastrocnemius anatomical cross-sectional area (in cm²)

Gastrocnemius medialis distal

Pre-test IG: 1.014 ± 0.235, Pos-test IG: 1.246 ± 0.293

Pre-test CG:0.97 ± 0.24, Post-test CG: 1.123 ± 0.261

Gastrocnemius medialis medial

Pre-test IG: 1.828 ± 0.224, Post-test IG: 1.893 ± 0.170

Pre-test CG: 1.744 ± 0.210, Post-test CG: 1.796 ± 0.213

Gastrocnemius lateralis distal

Pre-test IG: 0.792 ± 0.106, Post-test IG: 0.812 ± 0.195

Pretest CG: 0.836 ± 0.206, Post-test CG: 0.769 ± 0.15

Gastrocnemius lateralis medial

Pre-test IG: 1.372 ± 0.23, Post-test IG: 1.394 ± 0.174

Pre-test CG: 1.396 ± 0.226, Post-test CG: 1.378 ± 0.206

Peixinho et al. [70]

N = 20. IG: n = 12. CG: n = 8.

Plantar flexors

Unilateral, alternating stretch using 2 stretch exercises each 2 × 30 s per session. 4–5 sessions per week for 10 weeks.

Gastrocnemius cross-sectional area (in mm²)

Pre-test IG: 51.71 ± 11.02, Post-test IG: 52.3 ± 13.79

Pre-test CG: 50.94, Post-test CG: 52.21 ± 13.7

Reiner et al. [62]

N = 38, IG n = 19, CG n = 19

Pectoralis muscle

7 week pectoralis muscle stretching with 3 exercises performed for 5 min each

Maximal voluntary contraction in long muscle length in N

Pre-test IG 288.9±118.4, Post-test IG 332.4±117.0

Pre-test CG 267.5±97.3, Post-test CG 258.5±100.3

Maximal voluntary contraction in short muscle length in N

Pre-test IG 339.3±127.0, Post-test IG 365.6±124.7

Pretest CG 320.0±114.4, Post-test CG 301.8±118.0

Sekir et al. [71]

N = 34, static stretching n = 12, dynamic stretching n = 11, control n = 11

Peroneus longus, tibialis anterior

6 weeks stretching on 5 days per week for 4 × 30s, 2 muscles

Muscle thickness in the peroneus in mm

IG Pre-test 20.9±3.9, Post-test 19.6±2.4

CG Pre-test 22.9±4.4, Post-test 22.9±3.6

Muscle thickness in the tibialis anterior in mm

Pre-test IG 30.1±2.4, Post-test IG29.6±2.9

Pre-test CG 30.6±3.9, Post-test CG 30.6±3.0

Simpson et al. [63]

N = 21, IG = 11, CG = 10

Plantar flexors

6 weeks of stretching intervention

IG = Stretching on self-determined non-dominant leg. Organised into blocks of five days with 2 days of stretching one day rest. Using leg press machine for calf stretch. 3 min of stretch 5 times per week with load of 20% 1RM with a weekly increase of 5%.

Maximal strength in the plantar flexion (in Nm)

Pre-test IG 115.27 ± 18.49, Post-test IG 114.04 ± 11.36

Pre-test CG 104.21 ± 15.92, Post-test CG 111.72 ± 14.31

Muscle thickness in cm

5 days

Pre-test IG 1.7±0.05, Post-test IG 1.8±0.05

Pre-test CG 1.6±0.05, Post-test CG 1.68±0.05

21 days

Pre-test IG 1.7±0.05, Post-test IG 1.89±0.05

Pre-test CG 1.6±0.05, Post-test CG 1.7±0.05

42 days

Pre-test IG 1.7±0.05, Post-test IG 1.84±0.05

Pre-test CG 1.6±0.05, Post-test CG 1.73±0.05

Warneke et al. [26]

N = 52, IG n = 27, CG n = 25

Plantar flexors

Daily stretching training for 1 × 60 min using a calf muscle stretching device to induce stretching or 6 weeks. Stretching was performed with an intensity of 9–10 on a pain scale from 1–10

Maximal isometric strength in the plantar flexion with extended knee joint (in N)

Pre-test IG 1478.4 ± 309.7, Post-test IG 1726.00 ± 315.8

Pre-test CG 1585.4 ± 215.1, Post-test CG 1559.00 ± 217.8

1RM testing in the plantar flexion with extended knee joint (in kg)

Pre-test IG 91.9 ± 35, Post-test IG 115.0 ± 32.2

Pre-test CG 96.9 ± 27.6, Post-test CG 95.0 ± 28.6

Muscle thickness (in mm)

Pre-test IG 14.31 ± 2.42, Post-test IG 16.5 ± 2.78

Pre-test CG 14.54 ± 2.32, Post-test CG 14.85 ± 2.08

Warneke et al. [19]

N = 70,

IG1 = 25

IG2 = 15

CG = 30

Plantar flexors

IG1 and IG2 performed a daily stretching program for six weeks. IG1 performed one hour stretching per day, IG2 performed two hours stretching per day

Both groups used a calf muscle stretching orthosis

Maximal isometric strength (in N)

Pre-test IG1 1195.3 ± 321.09, Post-test IG1 1364.54 ± 355.43

Pre-test IG2 1144.2 ± 244.7, Post-test IG2 1397.9 ± 366.5

Pre-test CG 1076.3 ± 364.5, Post-test CG 1056.0 ± 332.7

Warneke et al. [25]

N = 35, IG n = 17, CG n = 18

Plantar flexors

The IG performed a daily 10-minutes static stretching program using a calf muscle stretching board. The intervention was performed for 6 weeks

Maximal isometric strength (in N)

Pre-test IG 2672.8 ± 688, Post-test IG 2918.7 ± 953.7

Pre-test CG 2204.4 ± 920.5, Post-test CG 2192.7 ± 953.7

Warneke et al. [24]

N = 46, IG n = 23, CG n = 23

Plantar flexors

Daily stretching training for 6 × 10 min using a calf muscle stretching device to induce stretching or 6 weeks. Stretching was performed with a intensity of 9–10 on a pain scale from 1–10

Orthosis was re-adjusted after 10 min of stretching to improve stretch intensity

Maximal isometric strength in the plantar flexion with extended knee joint (in N)

Pre-test IG 1697.67 ± 389.76, Post-test IG 1856.81 ± 431.28

Pre-test CG 1623.86 ± 251.52, Post-test CG 1645.00 ± 275.00

Maximal isometric strength in the plantar flexion with bent knee joint (in N)

Pre-test IG 1507.19 ± 333.16, Post-test IG 1580.29 ± 364.56

Pre-test CG 1413.10 ± 273.79, Post-test CG 1415.29 ± 266.23

Muscle cross sectional area in the lateral head of the gastrocnemius (in mm²)

Pre-test IG 1015.33 ± 269.78, Post-test IG 1095.87 ± 275.74

Pre-test CG 1002.06 ± 216.72, Post-test CG 1022.06 ± 236.02

Muscle cross sectional area in the medial head of the gastrocnemius (in mm²)

Pre-test IG 1715.54 ± 529.18, Post-test IG 1803.00 ± 535.64

Pre-test CG 1617.41 ± 428.08, Post-test CG 1630.35 ± 417.95

Muscle thickness in the lateral head of the gastrocnemius (in mm)

Pre-test IG 14.58 ± 3.17, Post-test IG 15.54 ± 2.77

Pre-test CG 14.25 ± 2.52, Post-test CG 14.36 ± 2.53

Muscle thickness in the medial head of the gastrocnemius (in mm)

Pre-test IG 18.43 ± 3.31, Post-test IG 19.66 ± 3.15

Pre-test CG 17.64 ± 3.29, Post-test CG 17.9 ± 3.28

Warneke et al. [23]

N = 69, stretching group n = 23, strength training group n = 23, CG n = 23

Plantar flexors

Daily stretching training for 1 × 60 min using a calf muscle stretching device to induce stretching or 6 weeks. Stretching was performed with a intensity of 9–10 on a pain scale from 1–10

Stretch training was compared to an commonly used resistance training routine for the plantar flexors

Maximal isometric strength in the plantar flexion with extended knee joint (in N)

Pre-test IG 1522.61 ± 310.25, Post-test IG 1796.78 ± 368.08

Pre-test CG 1557.05 ± 284.46, Post-test CG 1607.80 ± 361.11

Maximal isometric strength in the plantar flexion with bent knee joint (in N)

Pre-test IG 1314.7 ± 305.79, Post-test IG 1440.61 ± 332.67

Pre-test CG 1334.76 ± 235.36, Post-test CG1340.33 ± 205.81

Muscle thickness in the lateral head of the gastrocnemius (in mm)

Pre-test IH 14.53 ± 2.43, Post-test IG 15.21 ± 2.11

Pre-test CG 14.33 ± 2.48, Post-test CG 14.40 ± 2.32

Muscle thickness in the medial head of the gastrocnemius (in mm)

Pre-test IG 19.55 ± 2.59, Post-test IG 21.06 ± 2.88

Pre-test CG 18.49 ± 3.13, Post-test CG 18.41 ± 2.87

Warneke et al. [22]

N = 31, IG n = 18, CG n = 13

Pectoralis muscle

Pectoralis stretching on 4 days per week with 3 exercises each performed for 5 min for 8 weeks

Isometric maximal strength in N

Pre-test IG 649.99±337.07, Post-test 685.53±325.11

Pre-test CG 600.5±251.37, Post-test CG 643.61±241.67

1RM maximal strength (in kg)

Pre-test IG 75.35±33.62, Post-test IG 79.69±34.0

Pre-test CG 68.65±25.76, Post-test CG 69.19±26.11

Wilson et al. [64]

N = 32, CG n = 12, Immobilization group n = 10, Immobilization and stretching group n = 10

Plantar flexors

IG and Immobilization group had to use an immobilizator as long as as possible each day for 2 weeks. The stretching group had to perform a stretching routine for 10 × 30 s twice a day

Isokinetic plantar flexion peak torque (in %BW)

Pre-test IG 32.7 ± 7.2, Post-test IG 36.6 ± 8.5

Pre-test CG 34.83 ± 6.66, Post-test CG 32.92 ± 7.86

Pre-test Immobilization 37.1 ± 11.00

Post-test Immobilization 31.20 ± 6.66

Wohlann et al. [21]

N = 44, IG n = 22, CG n = 22

Hamstrings, quadriceps, plantar flexors

Stretching intervention consisted of 4 exercises for the lower extremity. Stretching was performed daily 5 min per exercise for 6 weeks, high stretching intensity was performed by using a stretching pain scale from 1–10, stretching should be set to 9–10.

Maximal strength in the leg press (in N)

Pre-test IG 789.1 ± 173.6, Post-test IG 823.8 ± 190.5

Pre-test CG 816.1 ± 168, Post-test CG 817.8 ± 179.9

Muscle thickness in mm

Pre-test IG 154.5±26.3, Post-test IG 164.8±27.7

Pre-test CG 163.4±24.4, Post-test CG 165.3±23.2

Wohlann et al. [20]

N = 81, stretching group n = 27, strength group n = 27, CG n = 27

Pectoralis muscle

Supervised pectoralis stretch for 8 weeks, continuous for 15 min, 4 days per week

Isometric maximal strength in N

Pre-test IG 461.3±196.6, Post-test IG 508.1±207.1

Pre-test CG 275.5±180.1, Post-test IG 479.1±179.4

Muscle thickness pectoralis left

Pre-test IG 25.7±7.3, Post-test IG: 27.4±7.4

Pre-test CG 27.3±6.6, Post-test IG 27.2±6.4

Muscle thickness pectoralis right in mm

Pre-test IG 25.7±6.9, Post-test IG 27.2±6.3

Pre-test CG 27.5±6.9, Post-test CG 27.3±6.8

Yahata et al. [65]

N = 16

Plantar flexors

Static stretching intervention of 6 × 5 min performed two times per week for 5 weeks using a stretching board

Maximal isometric strength in the plantar flexors at 30°plantar flexion (in Nm)

Pre-test IG 65.4 ± 15.9, Post-test 66.8 ± 17.6

Pre-test CG 64.2 ± 17.8, Post-test CG 59.4 ± 15.5

Maximal isometric strength in the plantar flexors in neutral position (in Nm)

Pre-test IG 158.8 ± 31.7, Post-test IG 167.9 ± 33.6

Pre-test CG 151.6 ± 34.9, Post-test CG 151.9 ± 34.1

Maximal dynamic strength in the plantar flexors at 30°/s (in Nm)

Pre-test IG 134.7 ± 27.5, Post-test IG 144.0 ± 25.4

Pre-test CG 128.0 ± 27.0, Post-test CG 131.1 ± 24.7

Maximal dynamic strength in the plantar flexors at 120°/s (in Nm)

Pre-test IG 82.9 ± 24.0, Post-test IG 84.2 ± 22.5

Pre-test CG 77.5 ± 20.2, Post-test CG 77.1 ± 17.6

Muscle thickness in the medial head of the gastrocnemius (in mm)

Pre-test IG 20.2 ± 2.1, Post-test IG 20.1 ± 2.0

Pre-test CG 19.2 ± 3.0, Post-test CG 19.3 ± 2.8

Muscle thickness in the lateral head of the gastrocnemius (in mm)

Pre-test IG 17.6 ± 2.4, Post-test IG 17.6 ± 2.3

Pre-test CG 16.5 ± 1.7, Post-test CG 16.8 ± 1.6