The central nervous system (CNS) plays the leading role in strength and speed development. When a previously untrained athlete begins a new training regimen, or an athlete sees a shift in stimulus, changes in the CNS can be expected. This is one reason why we shift through the Strength – Speed continuum the way we do: applying different levels of force at different velocities for maximum development. When training for power, whether it be with maximum speed or maximum strength, the CNS will adapt by recruiting larger motor units first to help with force production. Sometimes it is necessary to apply more force at the same rate, or it may be necessary to apply the same amount of force, but faster. These needs are determined on an athlete to athlete basis.
The neuromuscular junction is where a motor neuron meets a muscle fiber, and its job is to send the signals that facilitate a muscle contraction. The effect of training is the shortening of the distance between the neuron and the fiber, and thus a faster, more powerful contraction.
Training the Brain
Training the brain for performance requires considering the athletic demand for each sport. Soccer, for example, requires sustained periods of running. This is not true for golf. Golf requires the ability to execute the athletic motion fast, controlled and consistently, with several minutes rest between each motion. However, golf is a fast twitch dominant sport. We must implement exercises that stimulate the recruitment of fast twitch muscles AND promote a more synchronized pattern of firing. Endurance exercises, like distance running, promote asynchronous motor unit firing as a means for sustained performance over a long duration. These firing patterns reduce fast twitch performance, which is why running laps is not a highly effective exercise for golfers.
Instead, we focus on is sprint work, plyometric, and anaerobic conditioning, as well as strength work. All of these modalities work much the same way as maximum strength in that they wire the brain and muscle fibers to be faster in sending and receiving signals.
Fatigue
When training the CNS to be lightning fast, the implications of fatigue must be considered. Fatigue is a decrease in performance as a result of activities. During an intense training session, fatigue will eventually set in. In order to see an increase in performance, fatigue must be monitored. With exercises involving moving fast or heavy weight, the number of repetitions should be low, with adequate rest time between sets, which can be 2-6 minutes. If an athlete is doing high rep work, or not resting fully, he is simply wearing himself out with aerobic activity, and cannot hope to get much faster.
Cumulative fatigue is another factor to consider. It sneaks up on you, and it will zap motivation and performance. Cumulative fatigue can send the autonomic nervous system into a state where an athlete has put himself in a hole and cannot get out without rest. This is also known as “overtraining”, and it can wreak havoc on athletic performance late in a season.
Deload Week
This debilitating condition is the result of too much intensity or volume, an intense competition schedule, and a lack of adequate rest. The concept of a “deload” week is added to elite training programs to combat fatigue. At Par4Success, periodization (the modifying of training stimulus throughout the year based on athlete need) is used, especially during peak season to ensure maximum performance with minimal effects of fatigue.
Cumulative fatigue aka “overtraining” leads to a breakdown of technique due to less coordination or compensations and decreased power output. Poor technique is both detrimental to making progress and increases risk of injury.
Role of Cortisol
There is also a chemical aspect of cumulative fatigue. Cortisol, the body’s stress hormone, is very necessary for survival. It causes a surge of glucose into the bloodstream for energy. Thousands of years ago, cortisol was responsible for saving many humans from threats like saber tooth tigers, neanderthal attacks, and grizzly bears. Today, increased levels of cortisol are responsible for things like heart attacks and diabetes. When the body is under a constant state of stress, cortisol levels aren’t allowed to drop. Being overtrained is a constant state of stress and lead to increased levels of cortisol in the body which can cause:
- High blood pressure
- Poor thyroid function
- Decreased immune system
- Loss of bone density
- Loss of muscle mass
- Increase in fat stores, especially abdominal fat
- Inability to sleep
- Decreases in cognitive performance
- A “foggy” mind
- Slight depression
- Lack of motivation
- Inflammation
- Fatigue
For the athlete, these effects limit the ability to recover. If an athlete remains in this state for a sustained period, it could be a week or more before they return to normal. The intelligent athlete will keep an eye out for the signs of chronic cumulative fatigue and plan rest days and deload weeks accordingly.
Physical Effects of Overtraining
The physical effects of overtraining can range from a small ache to an acute injury or tear. Training, especially heavy training, causes tissue trauma. Proper rest time must be given to allow these microtears and the connective tissue to heal. Without this rest time, the athlete can develop anything from tendinitis to tears. Poor technique and overuse both contribute to these conditions, as compensations generally have an adverse effect on the body, especially over time.
To combat chronic fatigue we use recovery weeks that are known as deload weeks. The frequency for deload weeks depends on the athlete and their training. Every 6 weeks is generally a good place to start. If the deload weeks are too frequent, the athlete may not see the full benefits from training. If not often enough, the athlete is susceptible to chronic fatigue. The deload week can be implemented in two easy ways:
- Decrease Intensity by dropping it by 10-30%
- Decrease Volume by approximately 50%
Either method will result in less work done by the athlete for that week. A decrease in intensity is more likely to give the CNS system the rest it needs, so going from 90% to 60% for a week and keeping the same rep schemes is an easy way to implement it. Regardless of what strategy implemented, working with a skilled strength and conditioning coach can make determining the exact method needed easier.
Zac Hales
TPI-FP3
NASM-CPT
USA Weightlifting Sport Performance Coach
