Have you ever made it to a third set against a tough opponent, come close to winning but, due to fatigue, managed to only snatch defeat from the jaws of victory?! If so, you understand the role of proper physical conditioning when it comes to tennis. Unfortunately, too many players don't play enough sets (particularly THREE SETS IN A ROW) or train hard enough to get themselves in the best possiible position to win. Often times, this a result of lack of time or inexperience. However, assuming that you are motivated to learn and improve, here is one way to train for the third set if you only have one hour available:
Grab an equally motivated partner and play serving games up to 10 (or 11, 15, 21). One player serves the whole game and then the partners switch roles. Here's the kicker: each player should do 10 kangaroo jumps before each point. If you're tough, you will do 10 before the second serves as well. This will get your heart racing real quick and teach you how to think when you're physically and mentally fatigued. Another alternative would be to have only the person who lost the point do the jumps.
Here's the deal, "muscle fatigue leads to changes in interaction between structures of abrain's neural network", Fatigue-induced increase in intracortical communication between mid/anterior insular and motor cortex during cycling exercise (Eur. J. Neurosci. 2011 Dec;34(12):2035-42. doi: 10.1111/j.1460-9568.2011.07909.x. Epub 2011 Nov 20.; Hilty, L; Langer, N.; Pascual-Marqui, R., Boutellier, U.; Lutz; K.). As you may know, the cortex (see "intracortical" in the title of the article) plays a key role in memory, attention, perceptual awareness, thought, language, and consciousness. In the study (involving cyclists), there was a "lag" in the communication time between the various functions of the brain. See also Reduced muscle activation during exercise related to brain oxygenation and metabolism in humans (2010 Jun 1;588(Pt 11):1985-95. Epub 2010 Apr 19; Rasmussen, P., Nielsen, J; Overgaard, M., Krogh-Madsen R., Gjedde, A; Secher, NH; Peterse, NC): "Exhaustive exercise provoked cerebral deoxygenation, metabolic changes and indices of fatigue similar to those observed during exercise in hypoxia indicating that reduced cerebral oxygenation may play a role in the development of central fatigue and may be an exercise capacity limiting factor." Deoxygenation...hypoxia = being deprived of oxygen (suffocating).
In a sport as complex as tennis, where time is measure is fractions of a second, you cannot afford to have any kind of a lag - lapse in judgment - or central fatigue as that's exactly how the errors pile on. This is particularly true in a long three-setters where you are more prone for "taking the coward's way out" by hitting silly drop-shots, going for aces (including second serves), return winner or any other quick way for finishing the point. If you train yourself, your body will be more efficient at maintaining good energy for the duration of the match. Furthermore, your body will be better prepared to return the appropriate amount of oxygen and energy to the brain in order to stabilize its functions enabling you to make better decisions. Therefore, it is advisable that you incorporate some mentally stressful exercises into your routine so that you can understand the effects on your body and decision-making; know what you need to do (almost automatically) when you are in fact fatigued; and slowly push your tolerance levels beyond your comfort level thereby allowing you to play longer and higher quality matches.