Athletes often face sports-related injuries, which can hinder their physical abilities and reduce their competitive edge. In this regard, recent studies have shed new light on this issue, suggesting that such injuries may be part of a reversible involution process – which involves the regression of structural and functional tissues to an earlier stage, potentially allowing for recovery and restoration (1, 2). Temporary regression of biological systems is a stress-related response that affects individuals physiologically, emotionally, socially, and behaviorally. Within the allostasis-interoceptive paradigm, this phenomenon is commonly referred as cacostasis [“bad state”, from ancient Greek κακός (kakós) that means “bad”] to refer this state of disharmony and cacostatic load as the cumulative pathophysiological burden of the organism (3).

Sports injuries pose a significant and widespread challenge for athletes across various disciplines. These injuries disrupt training schedules, hinder competitive goals, and lead to profound physical, physiological, and psychological consequences (4, 5). Traditionally, sports injury management has focused on minimizing structural damage and alleviating pain as an effort to speed up recovery. Nevertheless, studying the nature of injuries as a biological outcome within the athletes’ allostatic response (6) presents a transformative perspective that could revolutionize approaches to rehabilitation and readaptation (7–9).

This perspective article explores the intersection between the cacostatic state and tissue involution into the context of sports injuries, proposing a novel operational framework for rehabilitation and readaptation. Through these connections, we aim to promote a practical rehabilitation and readaptation framework for sports injuries. By integrating the concept of reversible involution, we can usher in a new era of sports medicine—one that not only restores athletes to their pre-injury state but also propels them toward higher performance levels. Finally, we also explore the theoretical foundations of this concept and discuss its implications for musculoskeletal injuries, as well as its potential to transform holistic rehabilitation approaches.

Within the allostasis-interoception paradigm, allostasis refers to a biological system's ability to adapt to acute or chronic challenges through predictive adjustments to maintain viability (10, 11). Allostasis can be seen as a mechanism from which the body adjusts its physiological parameters within a range that is relatively harmless (e.g., increasing oxygen delivery to muscles during intense exercise, lowering heart rate during post-workout recovery, and redirecting blood flow from the digestive system to active muscles during physical activity), in response to changes anticipated from past experience, aimed at minimizing the future surprise (i.e., free energy). In this context of mathematical analysis and dynamical systems that follows Bayesian inference, allostasis is currently referred to as “variational and relational stability” by Bettinger & Friston (12), which expand upon the traditional concept of “stability through change” and highlight the inherent capacity of organic systems for physiological resilience, or the ability to “return to stability”.

Using sports injuries as an example, acute exercise-related impacts like falls, collisions, or strong tackles (external stressors) can also trigger systemic changes. These exposures recalibrate regulatory parameters to prioritize resource allocation toward activities critical for immediate survival (Figure 1A). The allostatic load, which represents the biological cost of adaptation, can then increase significantly when additional chronic stressors—such as those related to the magnitude, duration, quality, timing, and novelty of the stressor—exceed the system's coping capacity. This leads to a state known as allostatic overload, ultimately resulting in a cacostatic state. In 2022, we proposed this approach to analyze the etiology of pain and common injuries in weight-based resistance training (6) (Figure 1B). Interestingly, recent data validate this as allostatic load correlates with overuse musculoskeletal injuries during 10-week training programs in the US Marine Corps (13). Similarly, Feigel et al. demonstrated that increased allostatic load significantly linked to both physical and psychological maladaptation in military personnel (n = 31, 14F) completing a 10-week tactical training course (14).

In general, these processes can lead to tissue involution, characterized by reverse changes in the morphological and physiological features of biological tissues. Inflammation plays a key role in driving tissue involution due to its critical role in cellular responses to injury or stress. For instance, pathways to resolve inflammation are activated, genes related to tissue repair and cytoskeleton remodeling are upregulated, and energy expenditure increases—a phenomenon referred to as “allostasis and stress-induced energy expenditure” (6, 15). Over time, this can impair repair capacity, reducing the ability to regenerate tissues and potentially leading to diminished physical performance (16, 17), particularly due to low energy availability.

In the context of sports injuries, reversible involution refers to a temporary regression in affected tissues—such as muscles, joints, tendons, and ligaments—that disrupt normal function. The underlying basis of injury-induced involution lies in the principle of reversibility within the stress response. When exposed to stressors, the biological system regresses to earlier stages. Therefore, although tissues undergo regressive changes, they can achieve eustasis and return to their previous functional levels. The body's innate repair and regenerative mechanisms support this restorative process. Since the response to stress is dynamic and not permanent, tissue involution can be reversed through well-designed interventions focused on several aspects of healing and recovery (9). Recognizing that injury-induced involution is a transient, rather than permanent, condition allows practitioners to align their methods with the body's natural healing processes.

Rabey & Moloney recommended allostasis as a possible explanatory model for pain onset and persistence, suggesting that incorporating allostatic load into clinical reasoning could enhance decision-making (18). Indeed, in agreement with McClean et al., this underscores the necessity of treating sports injuries through a holistic framework (2). Such interventions may not only restore physiological parameters to eustasis but could also progressively optimize athletic performance reaching the state conceptualized as hyperstasis (3). This shift in perspective encourages the development of targeted systemic strategies (19) to promote tissue regeneration, reduce inflammation, and support reconstruction while preventing cortical changes (e.g., kynesiophobia), optimizing motor control, improving skill training and mental well-being (5) (Figure 1C).

This integration into sports clinical practice lays the foundation for a transformative rehabilitation paradigm, one that addresses not only the physical aspects of injury but also the psychological and emotional dimensions of recovery. By emphasizing reversibility and restoration, we can establish a unified, multidimensional strategy for sports injury rehabilitation and readaptation (7–9). Interestingly, while this exploration into rethinking sports-related injuries is still in its early stages, initial insights into the potential relationship between allostatic overload, the cacostasis state (i.e., tissue involution), and sports injuries (6, 13, 18) suggest a significant shift in the athlete recovery and development paradigm. Reconceptualizing injuries as transient evolutionary states rather than permanent setbacks encourages athletes and coaches to view challenges as opportunities to achieve peak performance.

Injury triggers a transitional involution in athletes’ motor development. This state of cacostasis is characterized by regressive factors such as loss of mobility, reduced functional capacity, and suboptimal metabolic responses. Understanding this connection is crucial for recognizing the potential for athletes to recover and adapt as they overcome these temporary setbacks. When athletes sustain injuries, particularly musculoskeletal lesions, they undergo a transitional involution process specific to their motor development. This process involves a temporary decline in motor coordination and physical abilities (20, 21). Transitional involution in motor development reflects a reduction in physical capabilities due to injury-related stressors, alongside physiological changes aimed at restoring lost skills and abilities.

This loss of mobility and functional capacity is one of the distinctive features of injury-induced involution. Athletes cannot move freely and perform even the most basic activities they used to do without difficulty. The physical loss this implies parallels the decay dimensions of cacostasis, during which people briefly lose their ability to handle complicated emotions or manage social situations adequately (13). As mentioned previously, the injury-induced involution affects the metabolic processes of an athlete which might disrupt peak efficiency and substrate utilization. This disturbance can lead to less efficient energy utilization and reduce the athlete's physical performance (14). Hence, nutritional strategies are essential for optimizing rehabilitation and readaptation. As we previously reported (22), key approaches include ensuring adequate energy availability and incorporating diets rich in protein and carbohydrates. Supportive supervision is crucial to prevent low energy availability. Sports nutritionists should aim for a carbohydrate intake of 6–8 g/kg/day to enhance glycogen restoration and reduce metabolic stress, supporting recovery and performance. For persistent muscle soreness or damage, frequent protein intake (4–5 times daily, 0.4 g/kg/meal) can aid repair. Additionally, consuming 25–30 g of protein before sleep may improve overnight recovery and muscle growth. Due to limited controlled clinical trials, definitive conclusions cannot yet be drawn regarding supplements like collagen, vitamin D, HMB, glucosamine, and other micronutrients. However, practitioners should weigh both the potential efficacy and strong safety evidence for creatine monohydrate (23) and omega-3 fatty acids (24) to inform clinical decision-making.

The systematic recovery of motor skills, mobility, and metabolic efficiency enables athletes to not only regain but also surpass their previous fitness levels. Recent neurophysiological advancements have introduced innovative rehabilitation strategies, such as action observation therapy, where patients observe a therapist performing actions to aid recovery (25). In contrast, motor imagery involves mentally simulating muscle actions without physical movement (26). Additionally, the cross-education effect—where training one limb benefits the untrained contralateral limb—has shown promise in injury rehabilitation. This approach, which improves outcomes without directly targeting the injured area, has gained attention for managing unilateral injuries like stroke-induced hemiparesis, osteoarticular injuries, and anterior cruciate ligament injuries (27). These techniques enhance recovery and muscle strength during rehabilitation and can be combined with psychological strategies to boost athletes’ motivation, helping them view injuries as opportunities to become more resilient, adaptable, and successful competitors (5).

The idea of sports injuries as reversible involution introduces a fascinating and transformative paradigm. This regressive tendency, relevant to sports injuries, highlights key factors that can enhance biological recovery toward eustasis and, ultimately, hyperstasis (3). Therefore, a holistic approach is essential for addressing musculoskeletal sports injuries. By examining injuries through the lens of allodynamic responses, practitioners can design personalized rehabilitation programs. Tailoring strategies to the athlete's unique experiences and needs can optimize recovery and support performance improvement. Our proposal is grounded in a well-established framework for rehabilitation and readaptation, widely accepted by coaches, medical staff, trainers, and other sports stakeholders (7–9) (Figure 2A).

Building on theoretical foundations, this framework outlines a comprehensive approach with six key steps to optimize human movement and physical performance. It serves as a valuable guide for designing tailored interventions and training protocols, grounded in theory, to enhance the complex interplay of postural control, mobility, proprioception, strength, coordination, agility, and endurance (see Figure 2B). These steps align with basic motor development abilities, though not all may be affected by injury. A thorough evaluation is necessary to identify which abilities have undergone reversible involution and require re-education or readaptation.

The concept of reversible involution in sports injuries marks a revolutionary shift in the paradigms of rehabilitation and recovery. This innovative approach opens up exciting opportunities for further research, promising significant advancements in recovery and performance optimization for athletes.

We outline the following key areas for future exploration in this topic: •

Molecular and Cellular Mechanisms, a deeper understanding of the molecular and cellular processes underlying reversible involution in sports injuries is essential. Research efforts should focus on elucidating the mechanisms that regulate the regenerative potential of injured tissues. Investigating signaling pathways and genetic factors will provide valuable insights into how the body achieves natural recovery and returns to an optimal functional state. Additionally, there is a notable gap in research validating allostatic load indexes in sports-specific contexts. Further studies are needed to explore how molecular and biomarker-based allostatic load measures can be applied to assess stress and recovery in athletes, particularly in relation to injury and rehabilitation. For further guidance, we encourage readers to access the 4R's of Sports Nutrition and newly developed allostatic load indices for athletes (28);

The concept of reversible involution reshapes how we approach sports injury rehabilitation, emphasizing the dynamic interplay between physical recovery and psychological well-being. Viewing sports injuries as reversible involution offers a transformative framework for rehabilitation and readaptation. By understanding the allodynamic responses of athletes, the progression to allostatic overload and cacostasis, and the process of tissue involution, practitioners can design targeted strategies to optimize recovery and restore pre-injury performance levels. Addressing the physical, emotional, and psychological aspects of an athlete's life enables recovery practitioners to adopt a more integrative and holistic approach. This comprehensive perspective not only enhances physical rehabilitation but also supports psychological resilience, empowering athletes to overcome injuries and reach optimal return-to-play.