## 3 Results
### Key Findings  
#### 3.3.1 Midportion Achilles Tendinopathy  
The authors of 21 out of the 50 studies were focused on the effects of conservative non-pharmacogical treatments for treating MAT [11; 12; 29; 30; 31; 32; 33; 34; 40; 51; 52; 53; 55; 56; 58; 66; 68; 70; 73; 76; 77]. ECC exercise, characterized by lengthening of the muscle with a purpose to maintain a certain load or because external resistance/load becomes greater than the force produced by the muscle [78; 79], was found to be effective as a rehabilitation protocol for treating MAT, as it caused a significant decrease in pain, an improvement in function [29; 32; 51; 77], an improvement in tendon properties (e.g., increase in tendon volume, decrease in tendon cross-sectional area, decrease in free tendon diameter, reduced tendon post-capillary filling pressure and capillary blood flow, increase in type I collagen synthesis, and reduction in tendon neovascularization) [32; 51; 53; 55], an increase in strength [34], and an improvement in ankle performance [55], and it caused an improvement in patient satisfaction compared to a baseline [29]. An increase in strength and improvement in function were found to have a relationship with a decrease in pain in the Achilles tendon after executing ECC exercise [32]. Whereas ECC exercise resulted in pain decrease, and function and tendon structure improvement in approximately 60% of patients with MAT [51], the proportion of patients who felt satisfied after executing ECC exercise ranged between 60 and 90% [29]. Meanwhile, [PERSON] et al. [53] reported that a 12-week ECC exercise program that consisted of 3 sets of 15 ECC heel raise repetitions with an extra load of approximately 120% of individual body weight, caused a statistically significant decrease in free Achilles tendon diameter with a negative effect size between \(-0.72\) and \(-3.53\) compared to a baseline. The average free Achilles tendon diameter or Achilles tendon anterior-posterior diameter needs to be measured 8 cm above the most inferior part of the calcaneus [80], and it should be lower than 5.9 mm in the healthy female and 6.9 mm in the healthy male population [80; 81; 82]. AT leads to swelling of the Achilles tendon (with 9 \(\pm\) 3 mm free tendon diameter measures) [83], and it can be decreased by executing ECC exercise protocols [53]. On the other hand, a 12-week ECC exercise program reduced Achilles tendon post-capillary filling pressure and capillary blood flow [34], which were increased at the point of pain [84; 85], and increased type I collagen synthesis [34]. Furthermore, 2-4 weeks were found to be enough for ECC exercise to cause a pain decrease and function improvement for patients with MAT, while the peak efficiency of ECC exercise was found at the end of the 12-week protocol [32]. Conversely, the tendon structure of the Achilles tendon with MAT stayed unchanged within the first few weeks of executing the ECC exercise, which is connected to the fact that the tendon structure has a poor relationship with a decrease in pain and improvement in function [32]. A decrease in pain, improvement in function, improvement in ankle performance, and reduction in tendon neovascularization were observed 6 or more months after the a 12-week ECC exercise protocol ended [55]. It was also found that both athletes and sedentary patients with MAT achieved similarly successful rates of outcome measures (such as pain decrease, function improvement, and strength increase) after executing ECC exercise [56]. The most frequently used ECC exercise protocol for treating MAT was HECT (heavy-load eccentric calf muscle training) or its modifications [33; 77]. The HECT regimen is a 12-week program that was founded by [PERSON] [27]. The HECT regimen consists of 3 series with 15 painful repetitions that need to be executed twice per day.