The stretch-shortening cycle (SSC) is a powerful model for studying normal and fatigued muscle function. It involves an eccentric (lengthening) phase followed by a concentric (shortening) phase, and is characterized by a significant force enhancement during the concentric phase due to the stretch reflex. This reflex contributes to force generation during the transition phase of SSC activities such as hopping and running. The amplitude of the stretch reflex and subsequent force enhancement can vary based on the degree of stretch and fatigue. Moderate SSC fatigue may result in slight potentiation, while exhaustive fatigue can dramatically reduce the reflex contribution. SSC fatigue is a useful model for studying reversible muscle damage and its interaction with muscle mechanics, joint, and muscle stiffness. These parameters and their reduction during SSC fatigue affect stiffness regulation through direct influences on muscle spindles and activation of III and IV afferent nerve endings. The resulting reduced stretch reflex sensitivity and muscle stiffness impair force potentiation mechanisms. Recovery of these processes is long-lasting and follows a bimodal trend. Direct mechanical disturbances in sarcomere structural proteins, such as titin, may occur as a result of exhaustive SSC exercise. The SSC model is also useful for studying neuromuscular fatigue, with in vivo force measurements revealing the recoil nature of the SSC and the role of the stretch reflex in force potentiation. The stretch reflex contributes to force enhancement during the eccentric phase of the SSC, and its interaction with muscle mechanics is crucial for efficient muscle function. SSC fatigue models have been used to study the effects of repeated impact loads on muscle performance, showing a loss of tolerance to stretch loads and changes in ground reaction forces. Recovery from SSC fatigue is delayed and follows a bimodal trend, with the second decline in performance peaking around the 2nd or 3rd day post-exercise. The coupling between muscle damage, reduced stretch reflex sensitivity, and deteriorated SSC performance is evident, with inflammatory processes playing a significant role in the recovery process. The stretch reflex is sensitive to passive perturbations and its sensitivity is reduced after exhaustive SSC fatigue. The recovery process is long-lasting and follows the bimodal trend, with the stretch reflex and ground reaction force showing similar recovery patterns. The SSC model provides valuable insights into the mechanisms of muscle function and fatigue, and its application in studying neuromuscular fatigue is significant.The stretch-shortening cycle (SSC) is a powerful model for studying normal and fatigued muscle function. It involves an eccentric (lengthening) phase followed by a concentric (shortening) phase, and is characterized by a significant force enhancement during the concentric phase due to the stretch reflex. This reflex contributes to force generation during the transition phase of SSC activities such as hopping and running. The amplitude of the stretch reflex and subsequent force enhancement can vary based on the degree of stretch and fatigue. Moderate SSC fatigue may result in slight potentiation, while exhaustive fatigue can dramatically reduce the reflex contribution. SSC fatigue is a useful model for studying reversible muscle damage and its interaction with muscle mechanics, joint, and muscle stiffness. These parameters and their reduction during SSC fatigue affect stiffness regulation through direct influences on muscle spindles and activation of III and IV afferent nerve endings. The resulting reduced stretch reflex sensitivity and muscle stiffness impair force potentiation mechanisms. Recovery of these processes is long-lasting and follows a bimodal trend. Direct mechanical disturbances in sarcomere structural proteins, such as titin, may occur as a result of exhaustive SSC exercise. The SSC model is also useful for studying neuromuscular fatigue, with in vivo force measurements revealing the recoil nature of the SSC and the role of the stretch reflex in force potentiation. The stretch reflex contributes to force enhancement during the eccentric phase of the SSC, and its interaction with muscle mechanics is crucial for efficient muscle function. SSC fatigue models have been used to study the effects of repeated impact loads on muscle performance, showing a loss of tolerance to stretch loads and changes in ground reaction forces. Recovery from SSC fatigue is delayed and follows a bimodal trend, with the second decline in performance peaking around the 2nd or 3rd day post-exercise. The coupling between muscle damage, reduced stretch reflex sensitivity, and deteriorated SSC performance is evident, with inflammatory processes playing a significant role in the recovery process. The stretch reflex is sensitive to passive perturbations and its sensitivity is reduced after exhaustive SSC fatigue. The recovery process is long-lasting and follows the bimodal trend, with the stretch reflex and ground reaction force showing similar recovery patterns. The SSC model provides valuable insights into the mechanisms of muscle function and fatigue, and its application in studying neuromuscular fatigue is significant.