Sports nutrition is witnessing rapid growth with a focus on discovering the link between nutrition & performance, ignoring nutrition’s role in EIMD.

What is EIMD?

High-force eccentric muscle action makes ultrastructural muscular disarrangements in Z-line streaming causing delayed onset of muscle soreness (DOMS), increased circulation of specific intramuscular proteins, swelling, less movement, hampered muscle force capacity & decreased pressure pain threshold immediately & for up to 14 days after the 1st exercise spurt.

The intensity depends upon exercise damage duration & individual’s vulnerability towards a damaging stimulus.  

What is the mechanism of EIMD?

Exercise forms resulting in EIMD comprise resistance training, prolonged running, downhill running & intermittent and high-intensity exercise. 

Primary damage – happens due to mechanical work conducted post-contractile & non-contractile disruption initiated by eccentric contraction. 

Secondary damage- additional damage is created by an unlimited number of Ca2+ moving inside the cytoplasm. This triggers Ca2+-dependent proteolytic & phospholipase A2 pathways causing protein structure damage. Subsequently, there is Ca2+ overload & permeabilization in the inner mitochondrial membrane and extensive efflux of Ca2+ from the mitochondria, with more intracellular Ca2+ concentration causing apoptosis. There is unmanageable muscle contraction, neutrophil infiltration, proteolysis & proinflammatory cytokine release. 

Muscle repair

Satellite cells get activated, and muscle regains the potential capacity to organize an increased response to a frequent myofiber homeostasis challenge. 

Muscle damage stretches indirect markers  

DOMS is the most commonly assessed marker which appears between 8 - 24 h after muscle-damaging exercise, peaks between 24 - 48 h & sinks within 96 h. 
2-6 days after initial damage, Cytokinine in plasma and myoglobin in serum appearance peaks.

Dietary Solutions for EIMD

Skilfully designed nutritional interventions are required to support the recovery process.

Protein and Amino Acids- 

Important for muscle protein turnover, adaptive processes, reducing muscle damage markers & enhancing recovery during exercise. 
Functional foods – 
•    Dietary polyphenols- 
Quercetin, Catechins & ellagitannins obtained from fruits & vegetables support recovery, provide antioxidant & anti-inflammatory benefits, and weaken arachidonic acid pathways.

•    Omega 3 PUFA- n-3 PUFA
Eicosapentaenoic acid (EPA) & docosahexaenoic acid (DHA) from nuts & oily fish give anti-inflammatory advantages. 

Vitamin D – 
An adequate dose is pivotal for the damaged muscle’s intrinsic repair at the cellular level. 
Vitamin C & E- 
May scavenge free radicals, and prevent cell damage & inflammation. 

Creatine Monohydrate- 

Furnish optimistic effects on satellite cell numbers & myonuclear content post exercise & influence skeletal myoblasts myotube formation. 

Practical cautious nutritional solutions to modulate EIMD
1.    Expand recovery, increase training stimulus, boost adaptive response & reduce performance injuries during EIMD
2.    Include a balanced diet enriched with fruits & vegetables
3.    Add nutritional supplements under the trainer’s & healthcare professionals’ supervision

Conclusion 

EIMD has a complex aetiology comprising difficult contributing factors that sometimes may amplify or resolve muscle damage. Sensible nutritional regimens can establish a delicate periodised steady approach during EIMD.