Rest and exercise are usually thought of as opposites, but they are actually complimentary and dependent upon one another. Just as night can only be defined in the context of day, exercise and rest are similarly connected. Rest is the single biggest determinant of exercise intensity. Without intense workouts, fitness results will be lacking and without rest, intensity will be compromised.
Think about it this way: a champion sprinter who attempts to sprint two 100-yard dashes immediately back to back with no rest will see a serious drop in intensity during the second race. The intensity generated in the first race would severely impede the performance of the second. With no rest between races, the sprinter could not physically or mentally muster the same effort. Resting between the two races is required to reset the body. Only with rest would the sprinter be able to push his body to its max for a second time.
The above scenario illustrates the concept of rest-based exercise. By focusing attention on rest during training, it is possible to reset both mental and physical capacity to achieve more than would be possible without it. Rest-based training is a new training philosophy that preaches that rest in a workout is not only a good thing, but should be the primary goal of any training program focused on delivering real results.
The pacing effect
If we told you we want you to run as hard and as fast as you can for 10 minutes, what would you do? Assuming you were up for a challenge, you might take off running. However, you would certainly not be able to run as hard and as fast as you are capable for the entire 10 minutes. Even the most elite athlete cannot sustain top intensity for more than 60 seconds. On a 10 minute run, you would necessarily need to control yourself. You know that in order to make it 10 minutes without stopping, not only could you not run your hardest, but you would need to regulate yourself. In fitness and athletics, this is called pacing and it is synonymous with long distance running and aerobic exercise. But if instead we asked you to run as hard and as fast as you can for 10 seconds, not only would you physically be able to do it, you would be more mentally up to the challenge.
When it comes to results-based fitness, pacing is a poor strategy for success because it is the antithesis of intensity. If you are pacing, than by definition you are not pushing as hard as possible. Pacing is also psychologically defeating. The example of the 10 minute run versus the 10 second run illustrates this point well. When pacing is employed as an exercise strategy, it automatically creates a built-in intensity ceiling. With the popularity of aerobic exercise and traditional bodybuilding workouts, duration of exercise has wrongly been credited as the chief driver of results. However, this is untrue for every parameter of fitness you may choose to measure. Higher intensity exercise excels at strength gains, delivers greater fat loss, and improves aerobic capacity far beyond workouts that are of longer duration and lower intensity. Yet in order to train at higher intensity, rest must be employed.
Physiology of rest
When the body is given a chance to rest and recover from a strenuous bout of movement, several beneficial physiological effects take place. Intense exercise generates metabolic byproducts that force the body to slow down. These byproducts are not necessarily a bad thing and their presence is meant to both protect the body and rebuild it after the workout has ended. However, they do interrupt the ability to sustain top performance. Most of us know that familiar burning sensation and extreme breathlessness that accompany hard physical effort. A short rest during this type of movement gives the body time to clear these metabolic byproducts, making maximum physical exertion possible once again.
Pacing has the opposite effect of rest-based training because it never approaches the intensity level required to produce these beneficial metabolic byproducts. As a matter of fact, the very purpose of pacing is to avoid the metabolic acidosis created from intense muscle action. In rest-based training, the biochemicals released from vigorous exercise are harnessed and used to create results. Lactic acid and other biochemicals released through intense exercise are some of the same molecules that induce the beneficial hormonal responses that grow muscles, increase endurance, and burn fat. Resting in a workout allows for the release stimulus of these chemicals one time after another. While it may take a marathon runner hours to reach this state, with rest-based exercise it becomes possible to harness this metabolic effect multiple times throughout one short workout.
Rest and muscle recruitment
Another important physiological mechanism is the use of muscle fibers. The body only uses the amount of muscle tissue required by the intensity of exercise. Lower intensity exercise uses less muscle fibers and high intensity exercise uses more. This effect is largely due to the fact that low intensity exercise only activates Type 1 muscle fibers. However, both Type 1 and Type 2 fibers are engaged during higher intensity exercise. Type 2 muscle fibers are perhaps the most important of the fibers, as they are involved in high-speed, power-type movements and have a greater capacity to grow, compared to Type 1 fibers. As exercise becomes more vigorous, the body is forced to engage more and more muscle tissue and Type 2 fiber stimulation increases. As the intensity rises further, so does the amount of metabolic waste and muscle fatigue.
In a paced workout, the goal would be to hold back and go slower so the muscles involved never get to a place of full fatigue and failure. In this scenario, only Type 1 fibers are engaged. However, in a rest-based workout, the very idea is too push the body to its limit engaging as much muscle tissue and releasing as many metabolic byproducts as possible. Training this way improves performance and results by increasing the amount of metabolic acidosis the body can tolerate and training the body to recruit more muscle tissue during exercise.
When working muscle fatigues, more muscle fibers are recruited to sustain movement. There is a point at which pushing even one more second is impossible, as the body approaches its failure point. It is at this point when the use of a brief rest allows the body to recoup just enough so that the muscle can be attacked once again with increased demand. During this second bout, the muscles will fatigue even quicker and the body will be forced to respond with even greater muscle recruitment. The effect is exponential as the rest-based workout proceeds. Inserting rest within intense exercise allows the body to engage more muscle than it would have been able to otherwise because the metabolic byproducts are cleared during rest but the muscles never fully get to recover.
A few studies
One interesting study in the February 2004 issue of the International Journal of Sports Medicine demonstrates the above points. In this study, four weeks of sprint training compared to standard aerobic exercise resulted in an increased ability to activate more muscle fibers in the legs in response to exercise. There was also a greater release of and tolerance for lactic acid in the sprint training group. These two affects would be highly beneficial in terms of performance for athletes and body composition changes for novice exercisers. Sprint training is impossible without rest between bouts. Another article from the Journal of Applied physiology (Nov 2007) shows Type 2 fibers are activated to much less a degree when exercise is continuous and sub maximal. And, in a resistance training study using brief one-second rest periods combined with various intensities of leg contractions, it was shown that short rest combined with high intensity contractions had the greatest affect on muscle fiber recruitment. This study was published in the European Journal of Physiology (Aug 2004 Vol 92).
Final Thoughts
The rest-based approach to exercise can be used for both aerobic and resistance training. This style of training has benefits in muscle fiber recruitment and elicits the same biochemical responses of interval training. The important thing to remember is that the rest should be as brief as it takes to recover and push hard a second time. The wording we like to use is “push until you can’t, then rest until you can”. In most interval style workouts, the rest periods are far too long for some or too short for others. The rest-based approach allows each exerciser to individually tailor the work and rest intervals for their unique level of fitness to generate big results. Switching your standard interval workouts and resistance training programs to a rest-based format will pay big dividends.