If you want to make a muscle stronger, you have to exercise it intensely enough to damage the muscle fibers and when they heal, they will be stronger than they were. You can tell you are causing muscle damage from the soreness in that muscle you feel four to eight hours later (Strength & Conditioning Journal, October 2013;35(5):16–21). This is called Delayed Onset Muscle Soreness (DOMS). On the next day, you should work out at reduced intensity. Most athletes set up their training programs to damage their muscles by taking a hard workout on one day, and then taking easier workouts until the soreness is gone.
How Muscles Get Stronger
Muscles are made up of thousands of individual fibers just like a rope is made of many fibers. Each fiber is a series of blocks called sarcomeres lined up end to end. Each sarcomere is attached to the one next to it at the “Z line.” Muscles fibers do not contract equally along their lengths. They contract only at each “Z line”. The damage that you feel from intense exercise occurs only at the “Z lines”
Repeating bouts of exercising your muscles intensely enough to damage them, followed by easy workouts until the muscles heal, makes muscles stronger so they can withstand higher loads and be more resistant to injury. When a muscle is damaged, your immunity sends to the damaged tissue large amounts of the same cells and chemicals called cytokines that are used to kill germs when you have an infection. This causes inflammation, characterized by soreness (pain), increased blood flow to the injured fibers (redness), and increased flow of fluid into the damaged area (swelling). The immune cells release tissue growth factors to heal the damaged muscle fibers, and you allow the muscle soreness to disappear before exercising intensely again. Muscle fibers become larger and increase in number by splitting to form new fibers. If you do not wait until the soreness goes away before exercising intensely again, the fibers can be torn, the muscles weaken and you can become injured.
What to Do When You Have DOMS
You can take off when you have DOMS if you want to, but you will become stronger by taking easy workouts while your muscles are sore. Athletes do not usually plan to take off workouts during recovery, even though resting when the muscles feel sore will allow muscles to heal faster than exercising at a low intensity. If you exercise at low intensity during recovery, your muscles will become more fibrous and resistant to injury when you stress them in the next intense bout of exercise. If you are a runner, run faster two or three times a week and much more slowly when you feel soreness on the days after running fast. If you are a weightlifter, lift heavy weights once or twice a week and much lighter ones on the following day or days when your muscles feel sore. If you are a basketball player, scrimmage hard for several hours on one day, then run plays and practice shooting on the next days when your muscles feel sore. If you play golf, practice your long drives on one day and practice putting on the following days when your muscles feel sore.
Stretching Does Not Prevent or Treat DOMS
Reviews of the scientific literature show that stretching neither prevents nor treats DOMS (Cochrane Database Syst Rev, July 6, 2011;(7):CD004577; Br J Sports Med. 2011;45:1249-1250). It did not prevent the muscle damage induced rise in plasma-CK, muscle pain, muscle strength and the PCr/P(I) ratio (Scand J Med Sci Sports, Aug, 1998;8(4):216–21). Stretching does not:
• prevent sports injuries (Clinical Journal of Sports Medicine, March 2005)
• prevent DOMS (Cochrane Database of Systematic Reviews, 2007, Issue 4)
• lengthen muscles (Clinical Biomechanics, June 2014;29(6):636-642). It only increases pain tolerance so you can stretch further.
Other Unproven Treatments for DOMS
Massage: Some studies show that massage decreases pain, but nobody has shown convincingly that massage hastens muscle recovery or increases contraction strength (J Athl Train, 2005 Jul-Sep; 40(3): 174–180). Massage did not hasten short or long-term recovery and was less effective for recovery than light exercise (J Orthop Sports Phys Ther, Feb 1997;25(2):107–12).
Heat did not reduce DOMS (J Strength Cond Res, Feb, 2004;18(1):155–61), but given on the day before exercise reduced muscle pain (Eur J Appl Physiol, Jan, 2007;99(2):183-92).
Cooling delays recovery from DOMS (J Strength Cond Res, May 2013;27(5):1354–61) and weakens muscles and impairs training (Eur J Appl Physiol, Mar 2006;96(5):572–80). Why Ice Delays Recovery
Nonsteroidals (such as ibuprofen) decrease muscle soreness but do not hasten muscle recovery (J Strength Cond Res, Feb 2003;17(1):53–9). In many studies, nonsteroidals did not even decrease muscle soreness (Brain Behav Immun, Nov 2006;20(6):578–84), and offered no benefit whatever (J Sports Sci, Mar 1999;17(3):197–203).
Cherry juice increased recovery for strength, but did not lessen pain or increase range of motion (Br J Sports Med, Aug 2006;40(8):679–83). I am always skeptical of studies that offer financial gain for a product. You would probably see the same benefit from a variety of other fruit juices or beverages.
Muscle Cramps Probably Caused by Muscle Damage
Even though muscle cramps are extremely common in competitive athletes, we really do not know what causes them. Nobody has shown consistent benefit from any of the most common treatments: multivitamin pills; mineral pills with calcium, zinc, magnesium, salt and/or potassium; massage or chiropractic manipulation; drinking large amounts of water; dietary manipulations; or bio-mechanical stretching and strengthening. Known medical causes of muscle cramps are extremely rare in athletes. These include narrowed blood vessels (usually from atherosclerosis), compression of nerves, low thyroid function, or side effects of medications such as diuretics. Some cramps are caused by low mineral or fluid levels (The Japanese Journal of Clinical Pathology, November 2007). However, in most people who suffer exercise-associated muscle cramps, blood levels of sodium, potassium, calcium and magnesium are normal. Research in athletes after they ran in 52-mile races showed that the runners who suffered cramps had the same level of dehydration and blood mineral levels as those who did not get muscle cramps. Cramping during exercise usually occurs in healthy people without any underlying disease or known cause.
I believe that the most common cause of exercise-associated cramps is damage to the muscle itself. Before you get a cramp, you will probably feel that muscle pulling and tightening. If you slow down, the pulling lessens, but if you continue to push the pace, the muscle goes into a sustained cramp and you have to stop exercising to work the cramp out. Further evidence that muscle damage is the cause of the cramp is that the muscle often hurts for hours or days afterwards.
Muscle Fatigue in Endurance Events Is Caused by Muscle Damage
When you exercise for a long time, your muscles start to burn and feel sore, which forces you to slow down. Muscle fatigue is caused by damage to the muscle itself (Medicine & Science in Sports & Exercise, July 2005). Running is much more fatiguing than cycling. When you run, your heel hits the ground and stops your leg from moving. This sudden stopping with each foot strike stretches your contracting muscles and tears them to cause a lot of muscle damage. These are eccentric contractions of muscles and they occur with far less force in cycling because you pedal with a smooth rotary motion and do not stop suddenly. The eccentric contractions during running cause a high degree of muscle damage, limit how far a person can run fast, and require far more rest days or easy days than cyclists need to take.
You can recover faster from intense exercise by:
• taking food and fluid within one hour after you finish exercising,
• sleeping after exercising, and
• moving as little as possible for several hours. You recover faster by lying down than by sitting, sitting rather than standing, and standing rather than walking.
Even if you don’t plan to compete in sports, you should set up a training program in which you exercise more intensely on one day and far easier on the next.
• On one day, take an intense workout, but only if your legs feel fresh after a five-to-ten-minute warm up. I think the best way to take an intense workout is to use some form of interval training. After your warm-up, pick up the pace for a few steps or pedal strokes, slow down until you feel comfortable again, and then alternate pickups and recoveries until your legs start to stiffen. Try to work up to the point where in each hard interval you go into the muscle burn and then immediately slow down.
• On the next day, your muscles may feel sore. Take your five-to-ten-minute warm up and if your muscles do not feel fresh, take the day off. If they feel fresh after your warm up, go slow anyway and always stop your workout when your legs start to feel heavy or you feel pain in one or more spots.
• Don’t plan to take days off, but if your muscles feel tired, heavy or hurt after your warm-up, go home.
• You should always stop your workout if you feel persistent pain in a localized area or your muscles start to feel stiff or hurt.
See also Strength Traihing Guidelines from Dr. Richard Winnett of Virginia Tech.
Caution: Check with your doctor before starting a new exercise program or increasing the intensity of your existing program