What is Exercise-Induced Muscle Damage?
Exercise is one of the best ways to stay active, healthy, and strong. However, people who exercise regularly have to consider the risk of muscle-damage because of strenuous workout sessions.
Exercise-induced muscle damage (EIMD) damages the muscle fibers because of extremely strenuous physical activity done for an extended period of time.
Usually, EIMD happens when a person goes through a new or an unaccustomed exercise regime. This is also a common problem for trainers and athletes who go through hours of rigorous physical regime every day.
While EIMD can cause physical pain and discomfort in common people, for trainers and athletes, it is a direct cause for lowered performance ability and can affect the range of motion, strength, and speed.
Symptoms Of Exercise-Induced Muscle Damage
- Delayed Onset Muscle Soreness (DOMS)
- Dull aching body pain
- Limited range of motion
- Z-band streaming
- Myofibrillar disruptions
- An increased presence of muscle proteins in the blood
- An increased presence of inflammatory markers in the blood
The symptoms of EIMD can start the next day of workout/exercise and can last for up to 2 weeks. The intensity of the symptoms depends on how hard you worked out and how long you worked out.
Exercise-Induced Muscle Damage During Training
Training for intensive events like the Olympics means you train really hard for years together. Some exercises like resistance training, high-intensity interval training, and eccentric training are all quite stressful on the muscles and, when not done right, can cause EIMD.
Eccentric training (Pushing the muscles well past their normal state of stress) is, especially, a very important cause for EIMD during training.
Primary and Secondary EIMD
There are two stages through which people experience EIMD after a session of intensive workouts.
This includes the symptoms experienced directly as an outcome of the exercise. Primary damage is further divided into two types.
1. Metabolic damage - Metabolic changes in the body, including metabolic waste accumulation, ions imbalance, and oxygen imbalance (hypoxia)
2. Mechanical damage - Continuous stress on the muscle fibers prevents them from producing as much force as they could before and also leads to Z-band streaming.
Secondary damage occurs as a result of primary damage. Intensive exercising leads to calcium moving into the cells as the body tries to maintain balance and regulation (a process called homeostasis). Intracellular calcium levels increase, and this further causes damage to the muscle fibers. Inflammation is an important sign of secondary damage.
How Does Genetics Influence Exercise-Induced Muscle Damage?
The TRIM63 gene encodes an enzyme called MuRF1. This enzyme is present in the M-line and Z-line of microfibrils and plays a role in signaling pathways in muscles.
A 2018 study analyzed the effect of genetic mutations of the TRIM63 gene on the body’s response to eccentric training/exercise. The study concluded that the people with the AA genotype of the SNP rs2275950 of this gene had stronger muscle fibers and showed resistance to EIMD when compared to people with the GG genotype.
The CCR2 gene receives signals when chemokines like CCL2, CCL7, and CCL13 are produced in the body. This gene reacts to these signals by increasing the levels of calcium ion levels within cells.
Genetic polymorphisms of the CCR2 gene greatly affect the ability to handle muscle damage.
The IGF-II gene helps in making a protein called the Insulin Growth Factor II. This protein plays an important role before birth in the development of cells into tissues.
A study that analyzed the effects of genetic polymorphisms of this gene in 151 subjects and concluded that the TT genotype of the SNP rs680 and the GG genotype of the SNP rs3213221 were risk factors for muscle damage in men.
The ACTN3 gene is called the ‘gene of speed’ and is usually present in elite athletes. This gene also plays a role in exercise recovery, adaptation, and risk of muscle damage.
Non-Genetic Factors That Affect Exercise-Induced Muscle Damage
Exercise Duration and Intensity
Logically, the more intensive your workout session is and the longer you put stress on your muscles, the more are the chances of developing EIMD.
A 2019 study compared the recovery time after a strenuous exercise session in younger and middle-aged men. The study concludes that younger men had lesser muscle damage after the exercise session and recovered faster too when compared to middle-aged men.
A lot of studies conclude women experience lesser muscle damage after intensive exercise/training when compared to men. A woman’s body produces lesser creatine kinase (CK) than a man’s body after a workout session. CK is responsible for muscle damage. Women also had lesser muscle inflammation than men after exercising. These studies suggest estrogen may play a role in protecting women from EIMD(https://journals.physiology.org/doi/full/10.1152/jappl.2000.89.6.2325).
If your diet majorly consists of items that can trigger inflammation in the body, the risk of experiencing damage in muscles after exercising is high. You should limit the intake of refined sugar, caffeinated energy drinks, alcohol, trans fat, and refined carbohydrates.
Recommendations To Manage Exercise-Induced Muscle Damage
The right nutrition available before and after exercising or training can prevent the risk of EIMD. Studies show the below types of natural foods can bring down the damage caused to muscles and reduce the intensity of EIMD.
- Tart cherries
These supplements also help bring down the effects of EIMD.
- Vitamin D
- Omega 3s
Eccentric exercising/training leads to oxidative stress in the tissues and muscles that make the signs of EIMD worse. This can be balanced by consuming antioxidant supplements. The most widely suggested antioxidants to prevent EIMD are vitamin C and vitamin E.
Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) can be used to prevent muscle soreness and muscle damage. NSAIDs are popular EIMD medications globally now.
Massaging is a widely followed therapy to handle the symptoms of muscle damage after eccentric training. A particular study concludes that massaging 2 hours after a strenuous session of exercise/training can bring down the risk of inflammation, reduce muscle soreness, and reduce the level of creatine kinase in the blood.
Repeated Bout Effect
It might be surprising, but the best way to prevent muscle damage after exercise is to repeat the strenuous session. This is called Repeated Bout Effect (RBE), and by repeating the training session, the body slowly gets used to the function and does not end up getting overly stressed the next time you train.
RBE can be used to bring down the extent of muscle damage in trainers effectively.
- Exercise-induced muscle damage (EIMD) is damage to the muscles because of excessive training or doing extremely strenuous workouts.
- Delayed Onset Muscle Soreness (DOMS), pain, inflammation, Z-brand streaming, and myofibrillar disruptions are some of the signs of EIMD.
- Genetic polymorphisms of the CCR2 gene, TRIM63 gene, IGF-II gene, SLC30A8 gene, and ACTN3 gene can affect a person’s resistance to muscle damage after training/working out.
- Nutritional supplements, including vitamin C, vitamin D, Creatine, omega 3s, and antioxidants, can all help repair damaged muscles and increase the rate of recovery after training. These bring down the severity of EIMD symptoms.
- Repeated Bout Effect (RBE) is a technique that puts muscles through rigorous training sessions soon after the symptoms of EIMD are seen. This helps the body get used to the physical stress. Trainers can use RBE to bring down the risks of EIMD.