Fatigue & Recovery

In order to understand recovery, there are several types of fatigue that must be considered.

  1. Neuromuscular fatigue
  2. CNS (Central Nervous System)
  3. PNS (Peripheral Nervous System)
  4. Muscular fatigue
  5. Endocrine fatigue
  6. Psychological fatigue
  7. Central Nervous System (CNS)

The CNS functions by sending nerve impulses to the working muscle instructing it to contract. The speed, size and rate of transmission of the nerve signals represents the relative state of the CNS. Under the stress of sport performance and training, physical capabilities will be negatively impacted by the decreased working capacity of the CNS. Fatigue induced changes occur in the motor centers of the cerebral cortex. These changes detrimentally affect the rate and speed of nerve impulses and the transmission to the working muscles. This is particularly true of maximal or near maximal strength and power due to the reliance on force, speed and rate of firing. Therefore, CNS recovery is particularly crucial for sports involving high levels of strength and power output.

Although the exact mechanisms for why the CNS experiences decreased excitation is not clear, the state of the CNS is largely governed by both the rate and speed of nerve transmission. However it appears clear that CNS fatigue is displayed through an impairment of;

  1. The transmission of spinal nerve impulses
  2. Recruitment of spinal motor neurons.

Peripheral Nervous System (PNS)

Metabolic changes within the muscle complex account for peripheral nervous system (PNS) fatigue. Again, impairment of nerve impulses across the neuromuscular junction (motor end plate), a reduction in peripheral nerve function and relationship that this has within the sarcolemma are the primary sites of fatigue.

Peripheral nervous system fatigue refers to exhaustion processes in the peripheral nervous system and the muscle caused by metabolic changes in the muscle complex. Decreased working capacity of the PNS occurs when the chemical byproducts of high intensity training build up to the point that the recruitment of spinal motor neurons deteriorates (occurring at a muscular level). It is related to issues such as impairment in the neuromuscular junction, decreased function of peripheral nerves and reduced electrical activity and activation of muscle fibers.

Causes of Neuromuscular Fatigue

  • Improper timing of stimulus
  • Improper manipulation of intensity
  • Excessive volume in training
  • Poor management of volume/intensity relationship

Signs and Symptoms of Neuromuscular Fatigue

  • Reduced heart-rate variability
  • Decreased motivation
  • Decreased willingness to train
  • Increased opposition to the training process
  • Decreased mental focus/concentration
  • Decreased quality of technical movements
  • Loss of strength and coordination
  • Involuntary trembling or shaking of muscles
  • Increased drowsiness
  • Difficulty sleeping
  • Moodiness
  • General malaise
  • Simple tasks seem difficult

Muscular Fatigue

Muscular fatigue occurs at the depletion of muscle energy substrates including ATP, Oxygen, Glycogen and the necessary contractual proteins.

Muscular fatigue is related to disruptions in the muscle components leading to microtrauma. The soreness, localised tenderness and stiffness do not occur immediately after exercise. There is a progressive build up that peaks between 24 and 72 hours later. This phenomenon is known as DOMS (delayed onset muscle soreness). The absolute alleviation of DOMS is representative of muscular recovery and supercompensation. However, it is important to identify the difference between nervous system recovery and muscular recovery, as the former will require longer periods of rest to fully regenerate. From this perspective, the fitness professional must be careful not to use muscular status alone to measure overall recovery.

Causes of Muscular Fatigue

  • Excessive volume in training
  • High focus on eccentric work
  • High focus on the “sets to failure” method

Signs and Symptoms of Muscular Fatigue

  • Soreness/achiness
  • Stiffness
  • Increased muscle tension
  • Decreased suppleness of muscle tissue
  • Localised tenderness
  • Decreased coordination
  • Decreased fluidity of motion
  • Decreased strength

3 Stage Model of Recovery

  1. HR, BP, chemical processes normalize, ATP-PC stores replenished (2 mins – 10 hours)
  2. Contractile proteins and connective tissue regenerated, energy stores replenished (10 – 72 hours)
  3. Complete CNS recovery (72 hours +)

Sages of recovery along the supercompensation cycle.

Stage three represents complete recovery and supercompensation.

  1. This model is used to demonstrate the different stages of recovery.
  2. These time guidelines should not be literally interpreted.
  3. Awareness of the signs and symptoms neurological and muscular fatigue are imperative in order to maximize the individuals recovery.

Endocrine Fatigue

Stress, whether through lifestyle or via overtraining can have a negative affect on hormonal processes. Our ability to recover from these stresses can be directly correlated to the level of function of our endocrine system and our hormonal balance. High intensity exercise will disrupt the normal hormonal processes such as the testosterone/cortisol ratio. Endocrine fatigue refers to a prolonged inability to cope with hormonal disruptions from physical, psychological and environmental stressors.

  • Endocrine fatigue refers to the hormonal fluctuations from the physical, psychological and environmental stresses
  • High intensity exercise will disrupt the normal hormonal processes.

Signs and Symptoms of Endocrine Fatigue

  • Difficulty rising in the morning
  • Continual fatigue not relieved by quality sleep
  • Lethargy
  • Decreased sex drive
  • Mild depression
  • Increased symptoms of PMS (pre-menstrual syndrome)
  • Decreased coping capacity
  • Increased irritability/emotional instability
  • Decreased focus
  • Decreased memory
  • Retarded recovery after exercise, sickness or injury
  • Increased resting heart rate
  • Increased resting blood pressure
  • Delay of recovery blood pressure post exercise
  • Postural hypotension
  • Decreased immune function
  • Weight loss
  • Loss of competitive desire
  • Increased incidence of injuries
  • Decreased levels of maximal power

Summary

Recognition of the neuromuscular, muscular and endocrine signs and symptoms of fatigue are imperative in order to maximize the athlete’s recovery.
The coach should be constantly probing for symptoms and looking for signs of fatigue.

Recovery Capacity

The major influences on recovery include but are not limited to:

  • Previous Training
  • Rate of Change of Program
  • Lifestyle Choices
  • Sleep
  • TravelMental/Emotional Stress
  • Restoration Techniques