Fatigue comes in many forms but there are two main components – physical (physiological) and mental (psychological). Good nutrition can help with both of these and each are equally important to manage, to improve performance and reduce fatigued during a long and intense training session.
This occurs through our muscles and cardiac system getting tired through repeated work or intense loads (1). Training helps to lengthen time to fatigue, not just by strengthening muscles but at a deeper level within our cells at a complex and biological level (1). However, Nutrition can also help.
Firstly, adequate carbohydrate loading is necessary so that you have good glycogen (carb and fuel) levels prior to starting a long training session. When your body runs out of fuel you will “hit the wall” during long exercise session. This usually happens after 90 mins if you are not topping up your fuel reserves during exercise, give or take depending on your exercise intensity (1). This also relies on you being full carb loaded. If you exercise really slow or at a very low intensity, you can go longer than 90 mins before hitting the wall. This is because you are burning predominantly fat, not carb stores, for your fuel (1). If you are well trained your inflection point when you start burning carbs, not fat, is extended. If you are fat adapted, meaning that your body is metabolically flexible and able to burn fat in the absence of carbs you will go longer before you start using your glycogen stores. If you eat from the first hour of exercise, you will go longer before the big wall of fatigue sets in (1).
Restoring your glycogen stores after a large exercise session is also really important through a meal high in carbohydrates, within an hour of exercise completing, if you are hoping to exercise again the next day. If you try to exercise again quickly without restoring your carb stores, you will fall flat very quickly. Within the first hour after exercise is when your body best absorbs the carbohydrate and stores this fuel as glycogen for use during your next exercise session. So don’t delay that post training meal (1).
If you can’t eat carbs during a long exercise session, eat protein, it’s not as good as a fuel source, but will spare your body breaking down protein for energy in the absence of carbs, or if your carb or fat reserves are low (5). Protein for good muscle recovery and growth after exercise is also important (5). Sufficient hydration is also imperative to reduce the speed at which physiological fatigue occurs as it keeps your core body temperature lower which reduces time to fatigue (hot core temperature = faster fatigue).
Weird tip – fast bowlers in the AUS cricket team don’t do all the team warm up before a game because out of all the team they have been found to heat up the fastest and to the highest degree. A lot of testing has shown that when they are hot they bowl slower, fatigue faster, have poorer results. So they do a light warmup, then retreat to the change rooms and put their limbs in ice baths before coming back out to do their job.
Other ways to improve physiological fatigue and performance would be through beet juice for endurance (increased oxygen to your lungs) or other supplements such as for shorter durations (i.e. sprints) (4).
Now with psychological fatigue there are a number of components – mood, motivation, pain, expectations, performance are the key drivers (2). So a new environment, stress of a big race day, a different routine, lack of sleep, lots of decision making and quick reactions (athletes in highly skilled sports suffer the most when they are fatigued) and heat can also play a large part (2)
Psychological fatigue can really tire you out, as much as the physiological aspect. Other than managing your stress, pain and hydration, nutrition can assist with psychological fatigue (2). Carbs absolutely fuel your muscles along with fat and to a lesser degree protein in your body, however only carbs can fuel your brain and central nervous system sufficiently, this affects your psyche (2). Yes your body can use ketosis to deliver fuel to your brain but it’s a slower and more complicated process to get energy from fat. So when you’re cranking your efforts up a hill you really need carbs, it’s like a short sprint – you need the quick energy release from those carb stores.
Now without carbs to fuel your brain it gets really tired really quickly – within 90 mins if you are fully carb loaded. This is why it’s imperative that on a long ride you eat some level of carbs, if not for your muscles then for your brain. Only do fasted training during a short lower intensity exercise session, otherwise your brain and immune system will suffer (1). A reduced mood or motivation is the first thing to affect an elite or endurance athlete if they are not getting enough carbs. It can really make the difference between pushing on or not through that pain or fatigue barrier (2). It can also affect your immune system by helping your body produce good antibodies that are needed in times of heavy stress, such as endurance exercise (1). But that’s another story.
Caffeine has a similar effect on the brain and hence psychological fatigue (3). it can make your body ignore the fatigue or lower the perception of effort needed to complete a big task such as climbing a hill. It’s recommended that you use caffeine shots not a cup of coffee which has variable caffeine content.
In terms of the power of psychological fatigue, they have done studies where trained athletes ride to complete exhaustion in a lab, i.e. the time riding is unknown at the onset (2). They are told to just keep riding until they can’t ride anymore. Scientists measure their power output in the last few minutes. Then after 10 mins rest they are told to ride for 1 minute more as fast as they can. They technically should be exhausted, 10 mins is not a long enough rest and recover. However, the athletes all rode that extra minute at a much higher power output than the last few minutes of the ride to exhaustion (2). This is because of the ability to overcome psychological fatigue. The riders all knew it was just 1 minute more so they could cope with this and could perform higher as a result. So as you can see, psychological fatigue can play a massive part in overall fatigue and needs to be managed as much as physical fatigue (2).
- Halson, S and Mujika, I. (2007) Models of Fatigue. in Howard G Knuttgen (Ed) The Olympic Textbook of Medicine in Sport. Blackwell, p49-67 (Please click on the ebook and goto p. 49).
- Marcora SM, Staiano W (2010) The limit to exercise tolerance in humans: mind over muscle? Eur J Appl Physiol. 109(4):763-70.
- Cox, Gregory R., et al. “Effect of different protocols of caffeine intake on metabolism and endurance performance.” Journal of Applied Physiology3 (2002): 990-999.
- Muggeridge, David J., et al. “A single dose of beetroot juice enhances cycling performance in simulated altitude.” Sci. Sports Exerc 46.1 (2014): 143-150.
- Tarnopolsky, Mark. “Protein requirements for endurance athletes.” Nutrition7 (2004): 662-668.