My friend jokes that I'm the laziest person she's ever met. All she sees me do is lie on the couch with my feet up, stuffing my face with carbohydrates. I convince her, in a reassuring voice, "I'm recovering."
Recovery may be the most overlooked aspect of training. Most athletes and coaches focus on the workouts. Improvements in fitness, however, occur during the recovery period between training sessions, not during the training itself. The human body is great at adapting to stress as long as that stress is applied in small doses. When the stress is too severe, or not enough recovery has preceded the new stress, injury can result.
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Positive physiological adaptations to training occur when there is a correctly timed alternation between stress and recovery. When athletes finish a workout, they are weaker, not stronger. How much weaker depends on the severity of the training stress. Recovery is characterized by two major processes: the reestablishment of homeostasis and adaptation.
Reestablishment of Homeostasis
Immediately after a workout, athletes begin to recover from the stress imposed by the workout, and reestablish homeostasis over the course of a few hours. This process is characterized by:
- decreases in heart rate and body temperature
- glucose sparing
- elevated fat oxidation
- glycogen and creatine phosphate resynthesis
- repair of cellular damage from free radicals
- lactate removal from muscles
- restoration of intracellular electrolyte concentrations and acid-base balance (pH)
Contrary to the reestablishment of homeostasis that lasts a few hours, adaptation is a process during which athletes respond to the repeated stress of training over time.
How much athletes adapt to training ultimately depends on how responsive their cells are to signals. Muscle cells are able to detect all kinds of signals—mechanical, metabolic, neural and hormonal, which are amplified and transmitted via signaling cascades, and lead to the events involved in gene expression. Signaling results in the activation of transcription factors, which are proteins that bind to a specific part of DNA and control the transfer of genetic information from DNA to RNA.
Many of the physiological and biochemical adaptations to training begin with an athlete's DNA, with the copying of one of its double helical strands (a process called replication). The replicated DNA strand, under the action of transcription factors, is then transcribed into messenger RNA (a process called transcription), and the messenger RNA is then translated into a protein (a process called translation). Finally, the protein is transported from the nucleus of the cell, where transcription and translation occur to the place where it will function.