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Weight Lifting and Post Exercise Muscle Recovery

By Dr. John M Berardi, Ph.D.
First published at www.fitdv.com, Mar 2002.

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Did you ever wonder what's really happening to your muscles during and after exercise? Sure, there's no doubt that something's going on down in those contractile fibers, something strong enough to make you walk like Frankenstein for a couple of days after your leg workout. But what exactly happens to make you unable to negotiate curbs and doorsteps? Well, since science can provide a little glimpse into the phenomenon of post-exercise muscle recovery, in this article I'll address muscle recovery from a scientific perspective. Therefore whether you're man, woman or child, you'll be able to explain your pain.

Conventional weight lifting consists of two distinct phases of movement. The concentric phase is the positive portion of the lift (i.e. the upward push on the bar during a bench press) while the eccentric phase is the negative portion of the lift (i.e. the downward lowering of the bar during a bench press). Each portion of the lift can contribute to the muscle damage seen during weight lifting as follows.

1) The eccentric portion of the lift is, by definition, a form of forced lengthening of the muscle. Forced lengthening with high weight loads causes microscopic tears in the small fibers that make up the muscle and the connective tissues. Since eccentric contractions tend to involve fewer muscle fibers than other contractions, each individual fiber that's recruited takes a large beating. Therefore during exercise, the muscle is physically damaged. (1;6)

2) The concentric portion of the lift, while the force is dispersed over more fibers, tends to require much more metabolic activity. This metabolic activity leads to depletion of muscle energy stores such as ATP and muscle glycogen (carbohydrate). This depletion, while exercising, may lead to greater susceptibility to the damage seen above. (1;3)

3) Both the physical damage caused as well as the metabolic depletion can lead to altered cellular calcium balance during and after the exercise. With this, the amount of calcium in the cell increases. This excess of calcium can activate enzymes that break down cellular proteins including contractile protein. In addition, calcium can build up in the mitochondrion of the cells, thereby decreasing cellular energy production. (1;3;21)

4) As a result of all of this disruption, the body signals for help. After all, there is dysfunctional muscle debris that needs to be cleaned up. So after exercise, fluid begins to build up in the damaged cells in order to bring immune cells such as neutrophils and macrophages to the site of injury. While these cells end up clearing away damaged tissue, their activity leads to the build up of pesky free radicals (these are why we think antioxidants are so important). Free radicals may cause further muscle damage, prolonging recovery time. (1;9;12;13;16)

5) While this cycle of destruction and healing persists, normal muscle function, such as the ability to take up and store carbohydrates is compromised. This leads to a prolonged recovery of muscle energy, further delaying full healing. (10;11;22)

While it's nice to know what's going on at the microscopic level of skeletal muscle after exercise, it's important to realize that these microscopic changes lead to some profound functional changes.

1) During conventional weight lifting, muscle force production (strength) is diminished for at least 1 to 3 days after the damage has occurred. This loss of strength, which may take 7-14 days to recover, is most likely due to several factors including the disruption of muscle calcium balance and energy production, the poor recovery of muscle energy during this period, and the decrease in muscle protein content. In addition, this loss of strength can cause you to feel like a 90-lb weakling for several days after exercise. Stay away from the beach for 7-14 days. (5;8;14;17)

2) Muscle swelling, as a result of fluid accumulation and immune cell delivery, occurs almost immediately after exercise. This swelling typically lasts 3-4 days but may take as many as 7 to subside. This swelling is associated with muscle stiffness, decreased range of motion, and an inability to comb your hair after arm day. This means bad hair days for 3-7 days. (1;16)

3) Everyone's favorite, delayed onset muscle soreness (DOMS), typically lasts from 2-4 days after exercise and is mostly gone within 5 days. This soreness may come as a result of both swelling and stiffness but some scientists now think that biochemical changes in the muscle may increase nerve sensitivity, leading to muscle pain. Sensitivity is one thing but crying is not allowed; in 5 days it will all be over. (1;16)

4) As discussed above, while the muscle is healing, its ability to "refuel" with carbohydrate is decreased because of disruption of the muscle glucose transport mechanisms. This means that no matter how many carbohydrates you eat, you simply can't get your muscle energy back up to normal for at least 48 hours after exercise. So don't convince yourself that pigging out on pizza and beer will help you recover more quickly from your sore muscles.

So this is a pretty scary picture, huh? Well, although it looks nasty, ultimately (about a 7 -14 days later) the muscle damage stops, the immune system does it's job, muscle energy is replenished, and the muscle fibers are built back up bigger and stronger than before.

I hope you now realize that the only way to get improve your muscle size and muscle strength is to allow adequate recovery time between performing exercises with the same muscle groups. Without adequate recovery of calcium balance, muscle energy, and muscle protein content, your muscle force will be lower with each subsequent workout, thereby reducing the quality of the workout in terms of the weight lifted. This is certainly not the way to get stronger. In addition, unless you wait until full structural recovery occurs, you will simply be destroying the new muscle tissue being formed to replace the damaged tissue. And this is no way to get bigger.

So how long should one wait between weight lifting bouts using the same body part? Well, based on the recovery data discussed above as well as the detraining data discussed in sidebar #1, it appears that when doing intense weight lifting workouts and letting nature take it's course, a period of 7 or more days may be a good starting point. However each individual may be different. In addition, as discussed in sidebar #2, certain recovery techniques may speed up healing.

A few individualized methods for knowing whether it's time to destroy the legs again are as follows.

1) Be sure that muscle soreness is completely gone.
2) Be sure that your range of motion has returned.
3) Be sure that your muscle strength is better than it was during the previous workout.
4) For those of you who like to quantify things, you can measure your relaxed muscle circumference before your training session and wait until the swelling has gone down.

Although I don't think that understanding why you can't get out of bed in the morning after a rough workout makes it any easier to do so, at least you'll now be able to better plan your workouts. This way you will be able to fully recover and your pain will not be in vain.

Detraining (Sidebar #1)

It's no surprise to anyone that a consistent weight-training program produces gains in muscle strength and muscle size. Initially, the strength changes occur as a result of increased neural efficiency. Long term increases in strength are a result of increased muscle mass. These gains in muscle mass occur as a result of changes in muscle protein status. As mentioned, allowing the muscle to fully recover from muscle damage can maximize these adaptations. Although it's difficult to determine exactly how long a muscle needs to fully recover, it is not a good idea to simply wait two weeks before training again. Therefore a fine balance must be reached between waiting until the muscle has recovered and not waiting so long that the muscle becomes detrained.

Detraining is defined as a prolonged period of reduced exercise volume or muscle inactivity. Interestingly, although frequent and intense exercise is needed to yield gains in muscle strength and size, detraining studies have demonstrated that muscle strength and power can be maintained with intense workouts separated by as much as 10-14 days. Other data show that muscle strength actually increases with 8 days of low volume exercise recovery and may even increase during 2- 8 days of complete detraining. In the detraining group, strength was lost only after 8 days of detraining (4).

It is clear that muscle force production improves with adequate recovery and this may come as a result of full repair of muscle damage and full muscle energy replenishment. This information, coupled with the recovery data discussed earlier, provides more evidence for the idea that approximately 7 days but no more than 10 days should separate intense weight-training workouts for a specific body part.

Recovery Techniques (Sidebar #2)

The normal recovery from weight training induced muscle damage brings with it a host of symptoms including decreased range of motion, increased muscle soreness, muscle stiffness, muscle swelling, and decreased muscle force production. In order to accelerate muscle recovery several recovery techniques have been suggested. These techniques include the following.

1) Light Exercise During Recovery - Research has shown that performing a few sets of light exercise with the sore and damaged muscles may decrease muscle soreness and increase force recovery (15;16). Both studies used approximately 50 easily performed submaximal contractions in order to promote this effect.

2) Massage - Research has suggested that muscle soreness can be improved with regular massage therapy, however this modality does not appear to increase blood flow or force recovery (2;18;19).

3) Underwater Warm Jet Massage - One study showed that 20 minutes of underwater jet massage therapy 3x per week might help maintain performance capacity during intense training (20).

4) Muscle Compression - In one recent study, a few days of continual compression of damaged muscle tissue decreased markers of muscle damage and increased force recovery (7).

5) Cold Water Immersion - Although few studies have been done with cold water immersion, athletes have reported good results with immersion in cold water for 20 minutes during the recovery period.

References

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