As the old saying goes you can have too much of a good thing. This is as true in exercise as it is in anything. Too much hard training and not enough recovery can lead to over-reaching and then on to over training syndrome.
OVERREACHING can be thought of as functional or non-functional. Functional overreaching is basically supercompensation theory. In a nut shell this means you train and become fatigued (disrupt homeostasis), you suffer a decrease in performance in the short term (days). However when recovered you will then have an increase in performance due to the physiological changes in the body from the training.
NON-FUNCTIONAL OVERREACHING means you take weeks to months to recover. You have exhausted yourself or have not given yourself enough recovery time (most likely both). Causing a stagnation or decrease in performance.
OVER TRAINING SYNDROM (OTS) takes months to years to recover. Syndrome = lots of causes.
Now imagine someone constantly overtraining and under recovering, the compensation wave will go down and down without ever reaching back up to baseline.
Homeostasis disturbance is not just physical stress. Emotional stress will also trigger the same physiological responses as physical stress. This is why you can get hot and sweaty when you are nervous. Adrenaline will be released when a threat is perceived, be that a predator or your boss! Perhaps you have noticed you can train harder on holiday and not feel exhausted the next day. This is because your body is dealing with a lot less stress (depending on your holiday). Stress is a necessary part of life, but too much is a killer. As athletes (and people) we should be looking to balance our life to minimise stress.
Chronic stress releases cortisol and supresses immune system. It will cause Adrenal exhaustion where the adrenal glands cannot keep up with the daily levels of stress leading to (amongst other things) exhaustion, lowered immunity, and sleep disturbances.
‘Unexplained under performance syndrome’ (UPSS).10-20% athletes training everyday will experience UUPS. Of these 15% will experience underperformance, and a feeling of constant fatigue. 21% will experience no improvement in performance and constant elevated fatigue levels. Obviously, this is shocking statistics and not what we want to experience. Makinnon et al, (2008)
Athletes should be tested regularly. A decline in performance is necessary to show overtraining syndrome. A 2.4% REDUCTION IN 100-400m time has been put forward as a marker. Hooper et al, (1993).
Beware if you see a sudden decrease in blood lactate response while over trained. This is termed the ‘LACTATE PARADOX’ as this would normally be a good thing. However this is due to higher levels of adrenocortisoids which leads to poor glucose uptake. This lowers levels of lactate and leads to higher rates of perceived exertion. Athletes will not be able to push for as long due to glucose uptake, so performance will ultimately go down. Unfortunately you will have to maximally test to find this out.
Other physiological markers are cortisol levels staying constant but Testosterone dipping in overreaching athletes. Termed the Testosterone/Cortisol measure.
Chronic glycogen depletion leads to protein breakdown in the muscles for energy. Less BCAA in bloodstream (due to protein being used as energy) can lead to serotonin upregulation that leads to neural fatigue.
The immune system will be lowered due to hard training. OTS has been linked to lowered immune system.
Microtrauma in muscles due to exercise or impacts will create an inflammatory response in the body. This can lead to chronic inflammation if not enough rest. Cytokine (protein messengers) levels rise, leading to unwanted physiological changes (see chart below). Also leads to neutrophil release (auto immune cells) leading to further damage and protein breakdown.
This leads to the question, how do I avoid this. Often you will hear people saying there is not such a thing as 'over training' just 'under recovery'. It is almost like a chicken and egg question. Ultimately we need hard training sessions to adapt and get stronger, but we also need recovery to allow the adaptions to take place. You cannot have one without the other.
Here are some easy ways to make sure you don't get yourself in trouble.
PROGRAMME REST AND RECOVERY DAYS!
EAT. You will need to be taking in extra if you are training daily. Make sure you are eating lots of vegetables and fruit to guard against oxidative stress.
Don't programme two hard days back to back.
Always leave something in the tank in training. Save the superhuman efforts for competition.
Measure your heart rate in the morning, if it goes up more than 10% think about taking a few easy days.
Make sure your recovery days are easy. If you have a run programmed run it slowly!
Try to cross train when necessary or practical. Between training blocks, or instead of a recovery run. Cycling/rowing are all non impact and will give your muscles a rest from the impact trauma of running.
Try to minimise stress in your life outside of training. Easier said than done, but relax and make sure you get to bed early. Socialise with friends and family (sensibly).
Hope this makes some sense and thanks for reading,