Do bone and muscle healing after exercise involve inflammation, resulting in elevated inflammatory markers?

From the Guidelines

Yes, bone and muscle healing after exercise involve inflammation, resulting in elevated inflammatory markers.

Inflammatory Markers

• Myoglobin: increases after physical stress in sports, such as a 238% increase after a soccer match 1
• White Blood Cells (WBCs): increase during and after single bouts of exercise, with the most pronounced responses after long-term, intensive endurance exercise sessions 1
• C-reactive protein (CRP): a marker of systemic inflammation, increases after exercise, such as a 152-fold increase after running an ultradistance foot race 1

Exercise-Induced Inflammation

Exercise-induced muscle damage leads to an inflammatory response, which is characterized by the release of various biomarkers, including creatine kinase (CK), myoglobin, and CRP 1.

Bone and Muscle Healing

The healing process of bone and muscle injuries involves inflammation, which is a necessary step for tissue repair 1.

Limitations of Inflammatory Markers

While inflammatory markers can be useful in monitoring exercise-induced muscle damage, their interpretation is not straightforward, and various factors, such as ethnicity, body composition, and exercise intensity, can influence their levels 1.

Clinical Implications

In clinical practice, it is essential to consider the individual athlete's characteristics, training history, and overall health when interpreting inflammatory markers 1.

From the Research

Involvement of Inflammation in Bone and Muscle Healing

• Bone and muscle healing after exercise involve an inflammatory response, which is characterized by the presence of inflammatory markers 2, 3, 4, 5, 6.
• The inflammatory response is a natural process that promotes tissue repair and regeneration, but excessive or chronic inflammation can be detrimental to the healing process 4, 5, 6.
• The time course of recovery following exercise-induced muscle damage depends on the extent of initial muscle damage, which in turn is influenced by the intensity and duration of exercise, joint angle/muscle length, and muscle groups used during exercise 6.

Role of Inflammatory Markers

• Biomarkers of inflammation, such as creatine kinase and lactate dehydrogenase, are elevated after high-intensity exercise and can be used to monitor the recovery process 2.
• The neutrophil/lymphocyte ratio is a useful marker for predicting the end of the postexercise recovery period 2.
• Cytokines, such as TNFα and IL17A, play a crucial role in modulating the inflammatory response and promoting bone healing 5.

Regulation of Inflammation

• The regulation of cytokine production in skeletal muscle cells is complex and involves the coordinated action of multiple cell types, including neutrophils, macrophages, and lymphocytes 4, 6.
• ARE-binding proteins, such as HuR and TTP/ZFP36, play a crucial role in regulating the stability of mRNAs encoding pro-inflammatory mediators and promoting the resolution of inflammation 4.
• Immunomodulation, such as the preconditioning of mesenchymal stromal cells with pro-inflammatory cytokines, can enhance the immunosuppressive properties of these cells and promote bone healing 5.