The central nervous system is involved in every aspect of sports performance and according to John Shepherd, understanding its role and utilising it to its fullest extent is crucial for maximum training adaptation.
The central nervous system (CNS) consists of the brain and spinal cord and acts as a control system for the body. The brain is a highly complex organ with many functions, but in terms of sports performance, the cerebellum and diencephalon regions are very important. Understanding their role indicates just how integral the CNS is to sports performance:
The cerebellum is the second largest part of the brain. It is involved in coordinating muscles to allow precise movements and the control of balance and posture.
The diencephalon contains two important structures called the thalamus and the hypothalamus. The former acts as a relay station for incoming sensory nerve impulses, sending them on to the relevant areas of the brain for processing. It is therefore responsible for letting your brain know what’s happening outside of your body. The hypothalamus plays a vital role in keeping conditions inside your body constant. It does this, for example, by regulating your body temperature, thirst and hunger, and by controlling the release of hormones from the nearby pituitary gland.
Receptor and effector organs
Receptor organs include the ears, eyes and crucially in the context of this article, muscles. These organs (as their name suggests) collect information, which is then relayed via the CNS. The CNS then interprets this information and sends it back to ‘effector’ organs. These carry out the body’s response to the stimuli.
There is some debate as to the extent of the automatic (unconscious) and interpreted (conscious) response of the CNS as it affects sports performance. Some actions are largely automatic, such as the stretch/reflex involved in the leg muscles when jumping. However, others appear to be more specifically interpreted by the brain, such as the fatigue signals received at the end of a marathon. In the latter example, this interpretation allows ‘will power’ to become a major influencing factor in determining the degree of success achieved.
Fatigue during a match/competition, or as a result of training programmes that do not account for the restoration of CNS energy, can have detrimental effects on sports performance – whether interpreted consciously or unconsciously (more later).
Sport background and CNS activation
Research indicates that prolonged sports involvement influences the way the CNS ‘controls’ muscular recruitment and patterning. For example, researchers from Finland investigated the influence of sports background on leg muscle coordination during concentric and drop vertical jumps(1).
Five different athlete groups were chosen as subjects: track and field jumpers, swimmers, footballers, and poor and good vertical jumpers. ‘Motor versatility’ was used as a research focus – the ability of an athlete from one sport to ‘transfer’ skill to another. The team wanted to find out about different movement models – ie how the sports performers recruited their muscles and the role of the CNS.
Not surprisingly, it was discovered that the jumpers performed the most powerful vertical jumps. Their legs had greater muscular stiffness compared to the swimmers – who turned out to be the poorest jumpers (their leg muscles were more attuned to kicking). Specifically, the scientists discovered that the CNS influenced the firing and recruitment patterns of the sports participants’ muscles.
For example, the agonist and antagonist muscles of the swimmers of both the thigh and lower leg showed a dominance of co-contraction instead of the reciprocal innervation that was displayed by the jumpers. Basically, the swimmers were unable to create the stretch/reflex action in their leg muscles as powerfully as the jumper’s muscles, due to a different firing pattern, which resulted in poorer jump performance.
The football players, meanwhile, showed an intermediate level of innervation. However, their jumping ability was mitigated by a tendency to produce a new burst of activity at the end of the contact phase while jumping. This was unlike the jumpers whose legs fired dynamically, rapidly and sequentially to produce jumping power. The footballers’ jumping movement was more contrived, displaying a more ‘staccato’ muscular firing rhythm.
The researchers attributed these differences to the specifics of the individuals’ sports and crucially years of relevant training and the effects these had on the CNS. They went on to conclude that, ‘Prolonged training in a specific sport will cause the central nervous system to program muscle coordination according to the demands of that sport’ and also added, ‘the learned skill-reflex of the CNS seems to interfere hierarchically in the performance program of another task’.
This is positive if you train correctly for your sport, thereby maximising the CNS’s potential to enhance the desired training effect. But it’s not so good if you change sports and have to adopt new movement patterns that might be compromised by your prior sport’s involvement. Neither is it good if you train in a way that compromises the CNS’s contribution to your sport (more later).
Monitoring the CNS in order to maximise sports training response
A focus on weight training, speed and power development, will exemplify the importance of very careful training planning and monitoring in terms of the CNS and how it affects sports performance. See table 1 for examples of training options that significantly stress the CNS.
Tudor Bompa, a leading authority on strength training, has researched effective strategies to construct and plan over time weight training programmes that can effectively improve sports performance while also maintaining the integrity of the CNS. As he writes, ‘Increasing evidence suggests that the CNS limits performance to a much greater extent than was once believed.’(2)
Training must be planned to enhance the capabilities of the CNS
Bompa’s focus on CNS training is about creating the best conditions for improved maximal muscular contraction. However, the insightful reader may have identified another dimension to CNS training beyond that of fatigue and that is the mental dimension.
As an example, to lift very heavy weights as quickly as possible requires considerable mental and physical effort and maximal neural stimulation. The athlete needs to be mentally ‘in the zone’. This probably goes a long way to explaining why motivational techniques and the use of music are able to help athletes improve mental focus, reduce the sensation of fatigue and increase performance.
In the 1980s, Bompa worked with Charlie Francis, the coach to ‘disgraced’ sprinter Ben Johnson. Although Bompa refutes involvement with drugs, he advised Francis on how to get the most from CNS training. ‘The Charlie Francis Training System’ makes for interesting reading in terms of the acknowledgement of the key role of the CNS in elite athlete preparation more than 20 years ago(3). The workouts of Johnson and the other athletes in the Francis stable were often rotated around their effects on the CNS. Prescribed rest was crucial in this respect, as was an ‘intuitive feel’ on the part of the coach as to when the athlete had ‘had enough’ in a particular workout.
As an example of this, after a top-level performance in training and/or competition, Francis would implement a ‘recovery training phase’ lasting seven to 10 days. This was often contrary to what the athletes expected as they were often so excited by their efforts that they wanted to do more competitions or 100% efforts. According to Francis, however, following that kind of impulse could have resulted in injury or a decline in the effectiveness of the CNS due to excessive stress, thus impairing sports performance.
In regard to track workouts, Francis would ensure that his sprinters would run no faster than 95% maximum pace. Indeed, Francis would cut specific sessions to save CNS energy – eg if an athlete ran a personal best in training, the session would be terminated there and then, without any further runs being performed. This would save CNS energy and reduce injury potential.
In terms of weight training to improve explosive power, Bompa’s philosophy is that repetitions are the key training variable in the fight against CNS fatigue. He advocates low numbers of reps, but with very heavy loadings in excess of 90% of 1RM in order to develop strength that will boost speed and power and optimise the contribution of the CNS. Recovery times between sets of 1-3 repetitions could be as much as six minutes!
Crucially, these loadings create a higher level of excitation and receptor/effector flow, more motor unit recruitment and greater neural stimulation. These loadings and recoveries are also recommended on the basis of their contribution to maximum power and strength expression, and also because they do not produce a large increase in muscle mass, which could be detrimental to an athlete’s power to weight ratio.
When planning a training programme it is very important to consider the placement of high intensity (CNS taxing workouts) and their proximity to one another. Bompa advocates 48 hours of recovery between such workouts. He also recommends that on the same training day more of the same training can be performed; this is in part due to the effect of potentiation (see box, below left) and also to create time, so that the next day can be used for CNS recovery. For example, a sprinter could perform a sprint workout and equally intense plyometrics on the same day. On the subsequent training day, however, workout options would be selected so as not to challenge the CNS – eg tempo runs (medium-paced runs that do not overly stress the anaerobic system) or strategy work (team talks, for example and ‘run throughs’ of plays performed at a low intensity).
The role of the CNS in enhancing sports performance needs special attention as it may hold the key to improved speed and power production, for example. Coach and athlete need to realise the importance of the CNS and implement strategies in training and competition to maximise its contribution to sports performance.
John Shepherd MA is a specialist health, sport and fitness writer and a former international long jumper
1 Electromyogr Clin Neurophysiol 2003; 43(3):141-56
2 Periodization Training for Sports, Bompa T et al; Human Kinetics, 2nd edition 2005
3 The Charlie Francis Training System – available from www.charliefrancis.com