The ability to control body positions and equilibrium while standing still or moving

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6 May 2020

Step 2: Incorporate skill-related fitness components

Written by:
Tommy Yau
Head of Fitness Education, True Group

Now that you have read part 1 (“Step 1: Understand the components of Health-related fitness” ) of our 2-parter, let’s proceed to learn how what skills you need for holistic physical fitness.

Skill-related Physical Fitness

While crucial to individuals aiming to excel in sports/games, many components of skill-related physical fitness are relevant to everyone as the benefits extend to everyday living and functional movement.  It only has an indirect connection with health but it is assumed that people who possess skill-related fitness are more likely to engage in regular activity and thus have enhanced health-related fitness and a lower risk of disease.  

Whilst you can improve your base level of skill-related physical fitness, know that there may be a limit to how much you can excel in them as many skill-related fitness components are likely determined by heredity. 

1. Agility
   Agility is the ability to rapidly change the position of the entire body in space with speed and accuracy. Being agile helps you be quick and nimble and increase your mind-body connection. Agility training also helps prevent injury as your body is trained to maintain proper posture and alignment when you move.

   Typically measured using a shuttle or zigzag run, agility tests commonly feature in screening tests for sports teams.

2. Balance
   Have you ever had to stand on one leg or on a small stool?  Balance helps your body maintain equilibrium while stationary or moving. 

   Generally considered to be of two types - static and dynamic – balance is typically measured using a balance beam or tests that require holding a stationary posture after changing body positions.

3. Coordination
   Coordination is the ability to use the senses, such as sight and hearing, together with body parts in performing motor tasks smoothly and accurately. This is important in every aspect of daily activity, from riding a bike to cooking and work. 

   There are many different types of coordination and coordination tests include hand-eye or foot-eye coordination activities such as juggling, dribbling a ball or hitting an object.

4. Power
   A combination of strength and speed, power is the rate at which one can perform work. It has also been defined as the ability to exert muscle force quickly, which is why some experts consider it to be a combination of skill and health-related physical fitness. 

   There are many different types of power and power tests. Examples of power tests include shot-putting and vertical jumping.

5. Speed
   We are all familiar with what speed is – it is the ability to perform a movement within a short period of time e.g. running speed, swimming speed, speed of hand or foot movement. 

   Among athletes, a 40-meter dash is often used to measure speed. There are a wide variety of laboratory measures of speed that are highly specific to different body parts and different human movement activities.

6. Reaction Time
   Reaction time relates to the time elapsed between stimulation and the beginning of the reaction to it, e.g. moving your foot from the accelerator to the brake pedal in an emergency to stop a car. 

   Like other measures of skill-related fitness, there are many different types of reaction time and many different tests available. Like speed, reaction time is considered to be a component of fitness that is greatly influenced by heredity.

So there you have it, a brief and concise round-up of the main health and skill-based components of physical fitness. Whilst there is so much more to each component if you delve into science behind them, we hope this article has given you a head start in crafting an appropriate training plan for yourself.  

To re-cap, start with your goal in mind e.g. is it to lose body fat, improve sport performance or to keep your body in top shape as you grow older. Next, incorporate the health-related components into your plan before moving on to the skill-related components.  Lastly, always ensure that you are working out in a safe and effective way.

Be consistent and never give up! 

[Updated: 13 May 2020]

Introduction[edit | edit source]

Postural control is the ability to maintain our body in space achieving both goals of stability and orientation[1]. through the process of rehabilitation, we aim to train patients on various tasks according to their activity limitations and participation restrictions to achieve independence in their daily activities and this independence can be achieved only when we put the various factors affecting each postural task into consideration

A Systems Framework for Postural Control[edit | edit source]

Balance emerges from the interaction of the individual, the task, and the environment; Functional tasks require three types of balance control, steady-state, reactive, and proactive. Environmental constraints such as type of support surface, sensory cues, and cognitive demands. Individual variations such as motor, sensory and cognitive abilities. Also, impact the control of balance.

Task Constraints[edit | edit source]

Activates of daily living require 3 types of balance control :

1. Steady-state balance is the ability to control our balance in fairly predictable and nonchanging conditions.
2. Reactive balance control is the ability to recover a stable position following an unexpected perturbation.
3. Proactive or anticipatory balance is the ability to activate muscles in the legs and trunk for balance control in advance of potentially destabilizing voluntary movements.

Reactive balance control relies on feedback mechanisms; on the other hand, proactive balance utilizes the feedforward mechanisms. Feedback control refers to postural control that occurs in response to sensory feedback from an external perturbation by ⠀⠀the postural control system⠀⠀ the postural control system from an external perturbation. Feedforward control refers to anticipatory postural adjustments that are made ahead of a voluntary movement that is potentially destabilizing to maintain stability during the movement. [2]

Most functional tasks require all three aspects of balance control. For example, reaching for a heavy object while standing requires steady-state balance to maintain a stable position before reaching for the object, anticipatory balance control to prevent loss of stability during the reach and lift, reactive balance control if the object is heavier than expected, and lifting it causes us to lose balance, and after that steady-state balance again after the completion of the task.

Steady-state balance[edit | edit source]

stability required for tasks like sitting or standing is called "static balance" but when we examine the amount of postural sway during these tasks and how our center of mass is controlled within the base of support despite it, we can see how steady-state balance, in this case, can be quite dynamic

Several factors contribute to our ability to maintain steady-state stability

1. Alignment of the body can minimize the effect of gravitational forces that tend to pull us off-center.
2. Postural tone to counteract the force of gravity the activity of the antigravity muscles increases during upright standing. Sensory inputs from the postural control system are critical to postural tone. Researchers have found that many muscles in the body are active during a quiet stance including
   1. the soleus and gastrocnemius, because the line of gravity falls slightly in front of the knee and ankle.
   2. the tibialis anterior, when the body sways in the backward direction
   3. Gluteus Medius and tensor fasciae latae but not the gluteus maximus
   4. the iliopsoas, which prevents hyperextension of the hips, but not the hamstrings and quadriceps
   5. the thoracic erector spinae in the trunk (along with intermittent activation of the abdominals), because the line of gravity falls in front of the spinal column.[3]
3. Movement strategies are not enough because both quiet stance and sitting are characterized by body sway, passive skeletal alignment, and postural tone; rather, movement strategies are needed to maintain stability even when standing or sitting quietly. for this we use one of two strategies during steady-state balance control; the hip strategy and the ankle strategy[4]

Clinical tests and measures that examine a patient's ability to sit or stand independently, such as the Berg Balance Scale (BBS), are examining steady-state balance.

Reactive Balance Control[edit | edit source]

Movement strategies used to recover stability in response to brief displacements can be categorized into two categories:

1. Fixed support strategies the previously mentioned ankle and hip strategy
2. Change in support strategies the step strategy and the reach to grasp strategy.

Movement patterns used to recover stability following perturbations are selected by the central nervous system (CNS) based on several factors, such as characteristics of the perturbation (e.g., direction and magnitude).

In both standing and sitting most of the postural sway occurs in the Anteroposterior direction, so here are some examples of muscle activity patterns (synergies) used to maintain Anteroposterior stability

1. Ankle strategy restores stability through body movement centered primarily on the ankle joint. Activation of the gastrocnemius produces a plantarflexion torque that slows and then reverses, the body's forward motion. Activation of the hamstrings and paraspinal muscles maintains the hip and knees in an extended position. Without the synergistic activation of the hamstrings and paraspinal muscles, the indirect effect of the gastrocnemius ankle torque on proximal body segments would result in the forward motion of the trunk mass relative to the lower extremities. It appears to be used most commonly in situations in which the perturbation to equilibrium is small and the support surface is firm.[2]
2. Hip strategy This strategy controls motion by producing large and rapid motion at the hip joints, the hip strategy is used to restore equilibrium in response to larger, faster perturbations or when the support surface is compliant or smaller than the feet
3. Step strategy A step strategy realigns the base of support under the falling center of mass by placing the feet in the direction of the perturbation
4. Reach to grasp strategy relies on extending the BOS by using the arms to grasp an external object for stability.

Research has demonstrated that during recovery of stability, we continuously change and add multiple synergies, depending on the context of the task at hand. This suggests that when retraining balance, it will be important not to limit training to the activation of a single strategy (e.g., ankle vs. hip vs. step vs. reach) but to create conditions in which strategies are continuously modulated. For example, The use of an ankle strategy (legs and trunk moving in-phase) is predominant when standing on a firm surface; however, there is a shift to using a hip strategy (legs and trunk out of phase) when standing on a foam surface[5]

[6]reactive balance control can be tested by various tests that aim to challenge the patient to regain balance after a challenging task, the following videos are an example of such tests

Proactive (Anticipatory) Balance Control[edit | edit source]

The Central nervous system (CNS) uses the sensory information gathered by the sensory systems and the information from previous experiences to predict the number of forces and control needed for the task ahead with also the ability to change and adapt to new information if the task turned out to be different than expected; for example when lifting a heavy object it (judging its heaviness upon its shape) the central nervous system prepares us with a magnitude of forces that makes us hold that object higher when we discover that it was lighter than expected, then we adapt to the new information (reactive) and this mistake of ours is saved and added to our proactive control for a better prediction in the future.[2]

Environmental Constraints[edit | edit source]

Changes in support surfaces affect the organization of muscles and forces needed for balance as we previously mentioned. Differences in visual and surface conditions affect the way sensory information is used for balance control. Finally, daily life often requires that we perform multiple tasks, affecting the way cognitive systems like attention are used for balance and adding more cognitive load to the task at hand.[2]

Summary[edit | edit source]

• Postural control emerges from the interaction between the task, the individual, and the environment
• Tasks can demand more than one form of control0; steady-state, proactive, or reactive
• Steady-state control is needed when we want to maintain balance in predictable and nonchanging conditions
• proactive postural control is needed to get our bodies ready to maintain our balance during a predictably destabilizing task
• reactive postural control is needed to maintain our balance in response to an unexpected perturbation
• Reactive postural control is achieved by using the feedback mechanism, while proactive postural control is using the feedforward mechanism.
• the environmental conditions at which the task is performed such as the differences in visual and surface conditions, and cognitive load.

References[edit | edit source]

1. ↑ Mancini M, Nutt JG, Horak FB. How is balance controlled by the nervous system. Balance Dysfunction in Parkinson&s Disease, Nutt JG, Horak FB, eds. Academic Press/Elsevier. 2020:1-24.
2. ↑ 2.0 2.1 2.2 2.3 Shumway-Cook A, Wollacott M. Motor control: translating research to practice. Lippincott Williams and Wilkins, Philidelphia USA. 2016.
3. ↑ Basmajian JV. Muscles alive. Their functions revealed by electromyography. Academic Medicine. 1962 Aug 1;37(8):802.
4. ↑ Creath R, Kiemel T, Horak F, Peterka R, Jeka J. A unified view of quiet and perturbed stance: simultaneous co-existing excitable modes. Neuroscience letters. 2005 Mar 29;377(2):75-80.
5. ↑ Runge CF, Shupert CL, Horak FB, Zajac FE. Ankle and hip postural strategies defined by joint torques. Gait & posture. 1999 Oct 1;10(2):161-70.
6. ↑ PaulPotterPT. Berg Balance Test. Available from: //www.youtube.com/watch?v=babsE0f8Hys
7. ↑ Catalyst University. Reactive Postural Adjustments | Strategies For Maintaining Balance. Available from: //www.youtube.com/watch?v=m678T_r62G
8. ↑ Dr. Dania Qutishat. Reactive Postural Control Test/ Pushes (External perturbations). Available from: //www.youtube.com/watch?v=2BxJKgrByfU

What is the ability to control body positions and equilibrium while standing still or moving?

Is the ability of the body to quickly change position and direction of the body?

Is the ability to maintain an equilibrium or body position?

What do you call the ability to control the body during motion?