Mechanical loading induced moderate increases in tendon stiffness, large increases in tendon modulus, and small increases in cross-sectional area |
Changes in tendon modulus were the primary moderator of changes in stiffness |
High-strain protocols induced larger increases in tendon stiffness than low-strain protocols |
1 Introduction
2 Methods
2.1 Search Strategy
2.2 Study Selection
Criteria | Inclusion | Exclusion |
---|---|---|
Participants | Human Any age Any sex Uninjured/healthy participants with no systemic or long-term problems which would alter tendon health and/or adaptation to exercise | Animal Participants with tendon-related injury (e.g., tendinopathies, direct lesions, ruptures) or post-surgical tendons (e.g., grafts, tendon transfers) Any long-term issue which would affect tendon health and/or adaptation to exercise, e.g., cerebral palsy |
Paper type | Original research articles | Reviews |
Editorials/commentaries/opinion papers | ||
Conference abstracts/papers | ||
Study design | Experimental designs, e.g., RCT | Descriptive designs, e.g., cross-sectional |
Outcome measures | Morphology/geometry (i.e., CSA) | Other tendon-related outcome measures |
Material properties (i.e., modulus) | ||
Mechanical properties (i.e., stiffness) | ||
Protocol | Lower limb exercise interventions, including: targeted resistance training; stretch–shortening activity (e.g., jump or plyometric); endurance training (e.g., running, cycling) ≥ 2 weeks in duration Two or more supervised resistance training sessions Loading parameters (repetitions, sets, or duration/time under tension) detailed | Periods of immobilisation prior to loading Unsupervised training or home programmes with training diaries only < 2 weeks duration No full description of training intervention |
2.3 Study Quality Assessment
2.4 Data Extraction
2.5 Data Processing and Analysis
3 Results
3.1 Yield and Study Characteristics
Source | Participants | Intervention | Tendon | ||||||||
---|---|---|---|---|---|---|---|---|---|---|---|
Author | Group | N (M/F) | Age (years) | Height (cm) | Mass (kg) | Duration (weeks), Frequency (n x p/wk) | Group exercise characteristics (intensity, volume, contraction/exercise type) | Stiffness | Modulus | CSA | Tissue |
Albracht et al., 2013 [5] | Exercise | 13 (M/F n/s) | 27 ± 5 | 180 ± 6 | 76 ± 7 | 14, 4 | High intensity, low volume iso | ✔ | ✖ | ✖ | AT |
Arampatzis et al., 2007 [19] | Low strain limb High strain limb | 3/8 | 29.5 ± 5.0 | 172 ± 5 | 64.1 ± 5.0 | 14, 4 | Low strain/intensity, low volume iso vs. high strain/intensity, low volume iso | ✔ | ✔ | ✔ | AT |
Arampatzis et al., 2010 [20] | Low strain limb High strain limb | 11/0 | 23.9 ± 2.2 | 178 ± 5 | 77.2 ± 4.1 | 14, 4 | Low strain/intensity, high volume iso vs. high strain/intensity, high volume iso | ✔ | ✔ | ✔ | AT |
Baptista et al., 2016 [95] | Con limb Ecc limb | 23/0 | 62.74 ± 2.2 | 172.02 ± 6.11 | 80.21 ± 14.82 | 12, 2 | High intensity, low volume con vs. high intensity, low volume ecc | ✖ | ✖ | ✔ | PT |
Bohm et al., 2014 [21] | High strain rate & Reference | 14/0 | 26.7 ± 4.2 | 182.3 ± 5.3 | 82.2 ± 13.1 | 14, 4 | High strain/intensity SSC vs. high strain/intensity iso + reference limb high intensity, low volume iso | ✔ | ✔ | ✔ | AT |
Long strain duration & Reference | 12/0 | 29.5 ± 3.0 | 177.6 ± 7.0 | 74.8 ± 7.3 | |||||||
Bohm et al., 2021 [17] | Intervention | 9/4 | 29 ± 5 | 178 ± 8 | 73 ± 8 | 14, 3–4 | High intensity, low volume iso | ✔ | ✖ | ✖ | AT |
Carroll et al., 2011 [62] | Placebo | 8/4 | 67 ± 2 | 170 ± 3 | 77.3 ± 4.4 | 12, 3 | High intensity, low volume con:ecc | ✔ | ✔ | ✔ | PT |
Centner et al., 2019 [71] | Heavy load | 14/0 | 26.1 ± 4.2 | 179.7 ± 9.2 | 76.4 ± 15.4 | 14, 3 | High intensity, low volume con:ecc | ✔ | ✔ | ✔ | AT |
Dalgaard et al., 2019 [104] | Non-contraceptive | 0/14 | 24 ± 1 | 167 ± 2 | 66.7 ± 2.2 | 10, 3 | Variable intensity, variable volume con:ecc | ✖ | ✖ | ✔ | PT |
Duclay et al., 2009 [105] | Ecc training | 10/0 | 23 ± 3 | 178 ± 8 | 73 ± 7 | 7, 3 | High intensity, high volume ecc | ✔ | ✖ | ✖ | AT |
Eriksen et al., 2018 [63] | Old heavy | 5/4 | 69 ± 2.2 | 170 ± 10 | 77.2 ± 15.2 | 12, 3 | High intensity, low volume con:ecc | ✔ | ✔ | ✔ | PT |
Very old heavy | 8/4 | 88 ± 3.7 | 171 ± 11 | 70.5 ± 13.5 | |||||||
Eriksen et al., 2019 [64] | Heavy resistance | 7/3 | 67 ± 2.3 | 171 ± 8 | 79 ± 14 | 52, 3 | Variable intensity, variable volume con:ecc | ✔ | ✔ | ✔ | PT |
Farup et al., 2014 [106] | Placebo Con | 11/0 | 24.1 ± 0.9 | 181.0 ± 1.7 | 77.9 ± 2.2 | 12, 3 | Variable intensity, variable volume con:ecc | ✖ | ✖ | ✔ | PT |
Placebo Ecc | |||||||||||
Fletcher et al., 2010 [60] | Iso | 6/0 | 22.2 ± 3.1 | 180 ± 6 | 68.2 ± 8.3 | 8, 3 | High intensity, low volume iso + intensity n/s R | ✔ | ✖ | ✖ | AT |
Fouré et al., 2009 [107] | Training/Jump | 9/0 | 18.8 ± 0.9 | 179.2 ± 6.1 | 68.5 ± 7.1 | 8, 2 | Variable intensity, variable volume SSC | ✔ | ✖ | ✖ | AT |
Fouré et al., 2010 [49] | Training/Jump | 9/0 | 18.8 ± 0.9 | 177.3 ± 6.2 | 68.4 ± 6.5 | 14, n/s | Variable intensity, variable volume SSC | ✔ | ✖ | ✔ | AT |
Fouré et al., 2011 [50] | Training/Jump | 9/0 | 18.8 ± 0.9 | 177.3 ± 6.2 | 68.4 ± 6.5 | 14, n/s | Variable intensity, variable volume SSC | ✖ | ✖ | ✔ | AT |
Fouré et al., 2012 [51] | Jump | 9/0 | 19.6 ± 1.8 | 177.3 ± 6.2 | 68.1 ± 6.4 | 14, n/s | Variable intensity, variable volume SSC | ✖ | ✖ | ✔ | AT |
Fouré et al., 2013 [108] | Ecc | 11/0 | 21.2 ± 2.7 | 177.1 ± 6.1 | 71.1 ± 5.8 | 14, n/s | Variable intensity, variable volume 34 sessions total ecc | ✔ | ✖ | ✔ | AT |
Geremia et al., 2018 [72] | Ecc | 15/0 | 26 ± 5 | 176 ± 7 | 75 ± 9 | 12, 2 | High intensity, high volume ecc | ✔ | ✔ | ✔ | AT |
Hirayama et al., 2017 [109] | Training | 11/0 | 22 ± 3 | 172.0 ± 5.8 | 66.9 ± 10.5 | 12, 3 | High intensity, high volume SSC | ✔ | ✖ | ✖ | AT |
Houghton et al., 2013 [73] | Plyometric | 7/0 | 21 ± 4 | 174.6 ± 3.1 | 73.7 ± 10.3 | 8, 2 | Variable intensity SSC | ✔ | ✔ | ✔ | AT |
Kay et al., 2016 [110] | Training | 13/0 | 20.0 ± 0.9 | 180 ± 10 | 75.9 ± 8.5 | 6, 2 | High intensity ecc | ✔ | ✖ | ✖ | AT |
Kongsgaard et al., 2007 [65] | Heavy Resistance | 12/0 | 24.6 ± 1 | 183 ± 2 | 80.9 ± 3.9 | 12, 3 | High intensity, high volume con:ecc vs. low intensity con:ecc | ✔ | ✔ | ✔ | PT |
Light Resistance | |||||||||||
Kubo et al., 2001 [51] | Short duration | 8/0 | 22.6 ± 2.8 | 171.5 ± 6.1 | 69.2 ± 5.8 | 12, 4 | High intensity, high volume iso vs. high intensity, low volume iso | ✔ | ✖ | ✔ | QT VL apon |
Long duration | |||||||||||
Kubo et al., 2001 [52] | Iso | 8/0 | 22.6 ± 2.8 | 171.5 ± 6.1 | 69.2 ± 5.8 | 12, 4 | High intensity iso | ✔ | ✔ | ✔ | QT VL Apon |
Kubo et al., 2002 [111] | Resistance Training | 8/0 | 21 ± 2 | 172 ± 4 | 64 ± 6 | 8, 4 | High intensity, low volume con:ecc | ✔ | ✖ | ✔ | AT |
Kubo et al., 2006 [112] | Iso | 14/0 | 20 ± 1 | 168 ± 4 | 60 ± 2 | 12, 4 | High intensity, low volume iso | ✔ | ✖ | ✔ | PT VL Apon |
Kubo et al., 2006 [113] | Short length | 9/0 | 24 ± 1 | 172 ± 6 | 70 ± 9 | 12, 4 | High intensity, high volume iso vs. high intensity, high volume iso | ✔ | ✖ | ✔ | QT VL Apon |
Long length | |||||||||||
Kubo et al., 2006 [96] | High load | 9/0 | 24 ± 1 | 172 ± 4 | 73 ± 13 | 12, 3 | High intensity con:ecc | ✔ | ✖ | ✔ | PT VL Apon |
Kubo et al., 2007 [85] | Plyometric/ Jump | 10/0 | 22 ± 2 | 170 ± 3 | 63 ± 8 | 12, 4 | Low intensity SSC vs. high intensity, high volume con:ecc | ✔ | ✖ | ✔ | AT |
Weight training | |||||||||||
Kubo et al., 2009 [114] | Iso | 10/0 | 22.3 ± 1.1 | 171.4 ± 6.1 | 63.8 ± 8.7 | 12, 4 | High intensity, low volume iso vs. high intensity, high volume con:ecc | ✔ | ✖ | ✔ | PT VL Apon |
Con:Ecc | |||||||||||
Kubo et al., 2010 [115] | Knee extension | 10/0 | 22.3 ± 1.1 | 171.4 ± 6.1 | 63.8 ± 8.7 | 12, 4 | High intensity con:ecc vs. high intensity con:ecc | ✔ | ✖ | ✔ | PT AT |
Plantar flexion | 10/0 | 22.5 ± 1.6 | 169.8 ± 3.3 | 62.7 ± 7.8 | |||||||
Kubo et al., 2010 [88] | Iso | 8/0 | 22.0 ± 0.8 | 171.2 ± 6.7 | 62.6 ± 9.3 | 12, 4 | High intensity iso | ✔ | ✖ | ✔ | PT VL Apon |
Kubo et al., 2012 [89] | Iso | 9/0 | 23.4 ± 0.6 | 174.5 ± 2.0 | 69.1 ± 3.2 | 12, 4 | High intensity, low volume iso | ✔ | ✖ | ✔ | AT |
Kubo et al., 2017 [86] | Iso | 11/0 | 22.5 ± 3.2 | 172.2 ± 2.5 | 60.9 ± 6.5 | 12, 3 | High intensity, low volume iso vs. low intensity SSC | ✔ | ✖ | ✔ | AT |
Plyometric | |||||||||||
Kubo et al., 2017 [116] | Con | 9/0 | 20.8 ± 0.5 | 173.6 ± 5.5 | 65.6 ± 7.7 | 12, 3 | High intensity, high volume con vs. high intensity, high volume ecc | ✔ | ✖ | ✔ | PT |
Ecc | |||||||||||
Laurent et al., 2020 [117] | Knee extended | 6/5 | n/s (adult) n/s (adult) | 180.5 ± 5.8 | 68.7 ± 14 | 10, 2 | Intensity n/s, variable volume SSC | ✔ | ✖ | ✔ | AT |
Knee flexed | 6/5 | 180.9 ± 10.5 | 69.7 ± 10.8 | ||||||||
Malliaras et al., 2013 [61] | Con | 9/0 | 29 ± 5.1 | 179 ± 9.0 | 79.0 ± 14.5 | 12, 3 | High intensity con vs. high intensity ecc vs. high intensity ecc | ✔ | ✔ | ✔ | PT |
Ecc | 10/0 | 28 ± 4.6 | 179 ± 7.5 | 76.0 ± 12 | |||||||
High load ecc | 10/0 | 27 ± 3.8 | 177 ± 8.3 | 75.0 ± 6.3 | |||||||
Massey et al., 2018 [66] | Explosive | 14/0 | 25 ± 2 | 174 ± 7 | 71 ± 10 | 12, 3 | High intensity iso vs. high intensity iso | ✔ | ✔ | ✔ | PT VL apon |
Sustained | 15/0 | 25 ± 2 | 175 ± 8 | 70 ± 8 | |||||||
McMahon et al., 2013 [67] | Short range | 6/4 | 19 ± 2.2 | 176 ± 15 | 75.7 ± 3.2 | 8, 3 | High intensity, variable volume con:ecc vs. Low intensity, variable volume con:ecc vs. High intensity, variable volume con:ecc | ✔ | ✔ | ✔ | PT |
Long range | 5/6 | 21 ± 3.4 | 175 ± 14 | 74.9 ± 14.7 | |||||||
Full range | 7/4 | 19 ± 2.6 | 171 ± 11 | 73.8 ± 14.9 | |||||||
McMahon et al., 2018 [68] | Trained males | 8/0 | 20 ± 1 | n/s | 81 ± 4 | 8, 3 | High intensity con:ecc | ✔ | ✔ | ✔ | PT |
Trained females | 0/8 | 19 ± 3 | n/s | 69 ± 3 | |||||||
Mouraux et al., 2000 [118] | Ecc | 6/4 | 24.7 ± 3.2 | n/s | n/s | 6, 3 | Variable intensity, variable volume ecc | ✖ | ✖ | ✔ | AT |
Ogiso et al., 2020 [119] | Non-muscle stimulation | 9/0 | 19.2 ± 0.8 | 169 ± 5 | 61.0 ± 3.5 | 3, 3 | High intensity, high volume SSC | ✔ | ✖ | ✖ | AT |
Onambélé et al., 2008 [120] | Resistance training | 6/6 | 70.2 ± 1.5 | n/s | n/s | 12, 3 | High intensity, variable volume con:ecc vs. high intensity variable volume con:ecc | ✔ | ✖ | ✖ | AT |
Inertial flywheel training | 6/6 | 69.6 ± 1.1 | n/s | n/s | |||||||
Quinlan et al., 2021 [121] | Young con Young ecc Old con Old ecc | 10/0 10/0 8/0 9/0 | 23.3 ± 3.8 25.3 ± 6.2 69.1 ± 3.0 67.5 ± 1.5 | 175 ± 1.3 176 ± 2.2 175 ± 3.3 176 ± 5.8 | 74.2 ± 4.4 73.0 ± 6.1 79.2 ± 8.5 76.8 ± 10.4 | 8, 3 | Low intensity, high volume con vs. low intensity high volume ecc | ✔ | ✔ | ✔ | PT |
Reeves et al., 2003 [69] | Training | 4/5 | 74.3 ± 3.5 | 163.4 ± 9.1 | 69.7 ± 14.8 | 14, 3 | Variable intensity, variable volume | ✔ | ✔ | ✔ | PT |
Reeves et al., 2003 [122] | Training | 3/4 | 73.6 ± 3.4 | 162 ± 10.7 | 69.4 ± 17.7 | 14, 3 | Variable intensity, variable volume | ✔ | ✖ | ✖ | PT |
Sanz-López et al., 2016 [123] | Ecc overload | 10/0 | 22.8 ± 4.2 | 179.8 ± 7.9 | 72.6 ± 6.7 | 6, 2 | High intensity con:ecc | ✖ | ✖ | ✔ | AT |
Seynnes et al., 2009 [70] | Training | 15/0 | 20.4 ± 2.2 | 177 ± 4 | 73.6 ± 6.3 | 9, 3 | High intensity con:ecc | ✔ | ✔ | ✔ | PT |
Standley et al., 2013 [124] | Aer cyc | 0/9 | 70 ± 2 | 165 ± 2 | 67.2 ± 4.1 | 12, 3–4 | Variable intensity, variable volume Aer (cyc) | ✖ | ✖ | ✔ | PT |
Tillin et al., 2012 [125] | Trained limb | 10/0 | 20 ± 2 | 182 ± 7 | 74 ± 7 | 4, 4 | High intensity, high volume iso | ✔ | ✖ | ✖ | VL Apon |
Vikmoen et al., 2016 [59] | Endurance + strength | 0/11 | 31.5 ± 8.0 | 169 ± 5 | 62.4 ± 5.2 | 11, 2 | Cc, variable intensity, variable volume con:ecc + Cyc/R | ✔ | ✔ | ✔ | PT |
Wakahara et al., 2015 [75] | Training | 11/0 | 26.5 ± 2.0 | 173.4 ± 4.6 | 67.9 ± 7.4 | 12, 3 | High intensity, high volume con:ecc | ✖ | ✖ | (Width) | VL apon |
Walker et al., 2020 [58] | Traditional training | 10/0 | 21 ± 2 | 178 ± 7 | 78 ± 12 | 10, 2 | Variable intensity, variable volume con:ecc vs. variable intensity, variable volume con:ecc | ✔ | ✖ | ✖ | PT |
Accentuated ecc training | 10/0 | 21 ± 2 | 179 ± 8 | 76 ± 11 | |||||||
Waugh et al., 2014 [74] | Training | 5/5 | 8.9 ± 0.2 | 136.3 ± 5.6 | 28.4 ± 4.7 | 10, 2 | Variable intensity, variable volume | ✔ | ✔ | ✔ | AT |
Waugh et al., 2018 [54] | Long rest | 7/7 | M: 30.1 ± 7.9 | M: 181.9 ± 5.8 | M: 83.2 ± 6.0 | 12, 3 | High intensity, high volume iso vs. high intensity, high volume iso | ✔ | ✔ | ✔ | AT |
Short rest | F: 29.9 ± 5.2 | F: 164.5 ± 7.5 | F: 61.3 ± 7.2 | ||||||||
Waugh et al., 2021 [55] | Long rest | 7/7 | M: 30.1 ± 7.9 | M: 181.9 ± 5.8 | M: 83.2 ± 6.0 | 12, 3 | High intensity, high volume iso vs. high intensity, high volume iso | ✔ | ✔ | ✔ | AT |
Short rest | F: 29.9 ± 5.2 | F: 164.5 ± 7.5 | F: 61.3 ± 7.2 | ||||||||
Werkhausen et al., 2018 [56] | Isometric | 5/6 | 26 ± 4 | 174 ± 9 | 70 ± 9 | 10, 3 | High intensity, high volume iso | ✔ | ✖ | ✖ | AT |
Werkhausen et al., 2019 [57] | Training | 5/6 | 26 | 174 | 70 | 10, 3 | High intensity, high volume iso | ✔ | ✖ | ✖ | AT |
Wu et al., 2010 [126] | Training/Jump | 11/0 | 22.1 ± 1.6 | 174.4 ± 7.6 | 65.8 ± 8.6 | 8, 2 | Variable intensity, variable volume | ✔ | ✖ | ✖ | AT |
3.2 Participant Characteristics
N | Age (years) | Height (cm) | Mass (kg) | |
---|---|---|---|---|
Child | 10 | 8.9 ± 0.2 | 136.3 ± 5.6 | 28.4 ± 4.7 |
Adult | 629 | 23.7 ± 4.5 | 175.5 ± 7.8 | 71.1 ± 10.0 |
Elderly | 124 | 70.0 ± 7.0 | 170.0 ± 7.8 | 75.4 ± 13.0 |