## 4 Discussion
Although it did not meet the inclusion criteria of this systematic review, a recent uncontrolled trial [93] compared the effects of concentrically-biased cable push-down and cable overhead extension exercises, and [PERSON] and colleagues [93] did not report significant alterations in the FL of the triceps brachii long head even when the concentric  
Figure 28: The effect size of the exercise interventions on the forearm flexors muscle thickness. The green colour indicates a large effect size. Abbreviations: MT, muscle thickness. Figure 27: The effect size of the exercise interventions on the elbow flexors muscle thickness, muscle cross-sectional area and muscle volume. The red colour indicates a small or trivial effect size, the yellow colour indicates a medium effect size, and the green colour indicates a large effect size. Abbreviations: CSA, cross-sectional area; MT, muscle thickness; MV, muscle volume. elbow extension starts from a fascicle lengthened position. This may be due to the effects of concentric training. A future RCT should examine the impacts of eccentric training on the FL of triceps brachii long head. In terms of the muscle size parameters, the triceps brachii MT has been found to be strongly correlated with elbow extension strength [41]. Additionally, the triceps brachii MT was stated as being significantly correlated with better swimming performance (r = \(-\)0.56) [36]. Moreover, elbow extensors' and flexors' muscle size parameters (ACSA, PCSA and MV) showed significant strong correlations with elbow joint torque (r = 0.705-0.945) [39]. Furthermore, the elbow extensors' cross-sectional muscle area (CSA) was correlated with rowing performance, and was the significant best predictor of arm pull during the rowing activity in rowers (r2 = 0.195) [37]. Elbow flexors CSA showed a strong correlation with elbow flexion maximal power (r = 0.81) [40]. Arm muscles CSA was significantly correlated with shot put performance (r = 0.68) [38]. The pectoralis major muscle CSA was strongly correlated with bench press strength (r = 0.866), and muscle volume was strongly correlated with bench throw peak power (r = 0.821) [43]. Either concentric, isometric, eccentric or blood-flow restricted resistance training modalities led to significant muscle hypertrophies. Based on these findings, athletes, healthy individuals aiming to increase their related performance or muscle strength parameters, astronauts after a space mission [94] and patients experiencing muscle atrophies after bedrest [95; 96], which were mentioned above, may refer to the training regimens that showed large effects sizes on increasing the pectoralis major, arm and forearm muscles' size parameters. However, exercise selection should cautiously be made due to the small numbers of studies included in each meta-analysis. Additionally, the infraspinatus MT was significantly correlated with shoulder external rotation strength in professional baseball pitchers (r = 0.287) [44]. The subscapular MT was the best single predictor for powerlifting performance in professional powerlifters [17]. However, this systematic review did not detect any RCTs focusing on exercise-induced alterations in these muscle architectural parameters. Future RCTs may be conducted to investigate exercise-induced alteration in these muscle architectural parameters in the relevant samples, such as exercise-induced alterations in the infraspinatus MT in baseball pitchers, in the subscapular MT in powerlifters, and in the fascicle geometry of the triceps brachii in swimmers. Regarding the effect size calculations of the RCTs, initially, none of the RCTs reported the required SDs of the mean changes from baseline for exercise and control groups. The difficulties associated with conducting a meta-analysis without this variable are well described in the literature [61; 62; 63].