In the seventies and eighties exercise proverbs such as “no pain, no gain”, and the famous “Feel the Burn” were used in relation to exercise intensities. Famous personalities promoted these sayings, resulting in the general public feeling that if they didn’t hurt then they weren’t working hard enough. The thought of having to go through pain to reap benefit from exercise naturally discouraged many people to participate in exercise activities. So why do you hurt when you train hard, is it necessary and what can you do to reduce the pain?
There are several different theories on why people ache following exercise. The problem generally occurs following an extensive layoff from exercise or from an abnormally hard workout. A temporary soreness may persist for several hours, whereas a residual soreness may last for 3 or 4 days. It has been found that eccentric muscle contraction (the muscle lengthens while under tension), and to some extent isometric contractions (the muscle is under tension but no significant movement is produced), generally causes the greatest discomfort. This can been seen especially in running – As any runner will know, aches and pains generally occur more from downhill running than uphill running. This shows it is the type of contraction rather than workout intensity as running uphill is more metabolically demanding.
The initial pain generally occurs immediately following exercise. This is due to Lactic Acid accumulation. A worse pain can actually occurs between 48 – 72 hours following exercise; this is known as Delayed Onset of Muscle Soreness (DOMS) and is often the result of minute tears in the muscle.
Immediate muscle soreness is directly related to the build-up of Lactic acid (and other waste products) in the muscle. These products actually leak out of the muscle cells and stimulate sensitive nerve endings nearby. Excess Lactic acid is generally removed after exercise within 30-60 minutes. Therefore the pain felt from lactic acid accumulation is often immediate but not prolonged. The lactic acid is produced when energy demands by the muscles exceed the oxygen supply or its rate of utilisation, i.e. Lactic acid is a by-product of anaerobic metabolism. Lactic acid itself is a good source of energy and can be regenerated once exercise is slowed and sufficient oxygen is once again available. There are several methods of overcoming Lactic acid build-up. Unfortunately the best form of overcoming the build up is a genetic endowment. The type of muscle fibres in the muscle has a significant effect on lactic acid accumulation. Slow twitch muscle fibres can actually utilise the lactic acid produced by fast twitch fibres, therefore people with higher levels of slow twitch muscle fibres can reduce the effects of lactic acid build up.
There is several training responses that can reduce the pain felt through Lactic Acid build up. Firstly, frequent specific high intensity anaerobic training can produce a more rapid rate of removal of Lactic Acid but this will only reduce the pain long-term. It has been previously recommended that lactic acid can be reduced by post-exercise massage, hot baths and stretching. These methods have not been significantly proven to assist with Lactic acid removal. A mild bike ride has a much better removal rate. This is due to the aerobic nature of the exercise allowing increased amounts of oxygen to enter the muscles. Increased blood flow caused by the light exercise can also assist with the removal of lactic acid to the Liver and Kidneys.
Muscle soreness can also be caused by minor tears in the muscle or connective tissue. In this case the pain should not be ignored. Resting the muscles for a few days often allows the tissues to repair themselves adequately. Stretching the muscles under this condition can have a disadvantageous effect. Once again a light cool-down walk or cycle will help. The reason for delayed soreness is a complicated one. Excessive exercise can cause tearing of the sarcolemma, the substance that covers and protects the muscle fibres. This tearing causes an influx of extracellular calcium into the muscle cells. Proteolytic and phospholipolytic pathways are induced causing degradation of contractile proteins and membrane phospholipids. In layman’s terms the extra calcium that leaks into the muscle cells tears up proteins and lipids. Inflammation of the muscle fibres results as cells repair and remove the necrotic tissue (debris). The pain is a result of stored chemicals repairing and regenerating the muscle fibres. The slow release of these chemicals is the reason for the delay in pain.
As mentioned, DOMS are often caused by the eccentric component of an exercise. In order to reduce DOMS it would be advisable to avoid eccentric muscle contractions. This is not practical, unless you have a very understanding training partner. The most successful method to avoid DOMS is to start training at a light intensity and slowly build-up. The first bout of exercise will have a significant prophylactic effect on the development of muscle soreness in subsequent exercise sessions. This effect has been seen to last for up to 6 weeks. This supports the thought of commencing exercise with light bouts. This will protect against severe muscle soreness initially. Although this method doesn’t guarantee complete protection from subsequent soreness this adaptive process produces a more resistant muscle to damage from similar exercise intensities.
Of course when discussing muscle soreness it is necessary to mention cramp. This is probably the worst of all muscular pains. It is a sustained spasm of an entire muscle that can last for just a few seconds up to several hours. Although cramp is associated with exercise it is not the primary cause. Cramp actually reflects low blood sugar levels, electrolyte depletion, dehydration, or irritability of the spinal cord neurones. All of which can be a subsidiary of exercise. Simultaneously squeezing and stretching the cramped muscle may help. To reduce the possibility of experiencing cramp it is recommended you maintain good energy and hydration levels before exercise.
Remember, exercise is supposed to be an enjoyable activity designed to provide health and fitness benefits. Exercising should not hurt.
Mark Mayes, BSc.