Work Physiology and Aerobic work capacity

WORK PHYSIOLOGY AND AEROBIC CAPACITY

Work physiology is a term associated with industrial engineering that is concerned how the human body copes with physical stress, work strain, and the working environment.

 

Work physiologists apply their understanding in evaluating and designing work spaces that reduce physical fatigue, eliminate occupational injuries, and increase overall productivity. They need to understand how the body performs under a variety of environmental conditions, the amount of rest it requires, and when it is able to work at peak levels.

 

Capacity for physical work

An individual’s physical tolerance to physical work is usually determined by the capacity of his or her cardiovascular and respiratory system sto deliver oxygen to the working muscles and to metabolize chemically stored energy.

 

Metabolism, respiration, and circulation are just a few of the body systems that physiologists study. They also take into account skeletal, muscular, and cardiovascular activity. Work physiologists are concerned with the metabolic cost of work and attempt to minimize it by making the work space as ergonomic as possible. 

 

A work physiology laboratory has all the equipment necessary to measure parameters like heart rate, oxygen consumption, and core temperature. This branch of physiology also studies the changes that result in the human body as a result of being exposed to single or multiple instances of work stress.Knowledge obtained from work physiology is used to design work spaces that suit a wide variety of people.

The goal of work physiology is to ensure that the worker performs his or her task safely in the most efficient manner possible within the work environment. Human beings come in all sizes and shapes, and this makes it challenging for work physiologists to design environments suited to every type. Normally, the environment isn't a controlled one — there may be loud noises, flying dust particles, and heat, for example, which the body has to deal with. This branch of physiology monitors the amount of energy people spend on their task and ensures that they aren't pushed beyond their physical capacity to work.

 

Matching people and their work

Obviously, it is important to match human capabilities with the related requirement of a given job. If the job demands equal the worker’s capabilities or if they exceed them, the person will be under much strain and may be not able to perform task. Hence, various functional stress tests, which are administered by a physician, have been developed to assess an individual’s capability to perform physically demanding work.

 

Work capacity or fitness level of an individual can be determined in laboratory by measuring the VO₂ max.  VO2 max is indicative of aerobic fitness level.

 

Aerobic work capacity is the highest amount of oxygen consumed during maximal exercise in activities that use the large muscle groups in the legs or arms and legs combined. Aerobic capacity, aerobic power, functional capacity, functional aerobic capacity, maximal functional capacity, cardiorespiratory fitness, cardiovascular fitness, maximal oxygen intake, and maximal oxygen uptake are terms that are often used interchangeably.

 

Aerobic capacity is commonly described by the o₂max, or maximal oxygen uptake. This measurement is an indication of (1) the ability of the cardiovascular system to provide oxygen to working muscles and (2) the ability of those muscles to extract oxygen for energy generation in the form of adenosine triphosphate (ATP).

 

VO_2max is a measure of the maximum amount of oxygen that an individual can use per unit of time during strenuous physical exertion at sea level. It is an important measure for several reasons:

(1) It serves as an index of cardiovascular and pulmonary function;

(2) It characterizes the functional capacity of the cardiopulmonary system to transport oxygen to the working muscles; and

(3) It is one of the limiting factors in endurance performance.

 

Men who are 20 years of age have an average maximal capacity of 3-3.5L/min; women of the same age have an average capacity of 2.3-2.8 l/min. At age of 60 the capacity is diminished to about 2.2-2.5 L/min. for men and 1.8-2.0 L/min for women.

 

An individual’s VO_2max can be measured or estimated by a variety of techniques, including treadmill running, cycle ergometry, arm cranking, and stair stepping, rowing, and walking.

 

The most common way to measure VO_2max is by open-circuit spirometry, whereby the individual breathes in ambient air and then the exhaled air is measured and analyzed. The amount of oxygen consumed (VO₂) can be computed on the basis of the composition of the inspired air by quantifying the volume (V) and oxygen (O₂) content of the expired air.

Work/rest cycles: Fatigue is an overexertion phenomenon that leads to a temporary decrease in physical performance. In order to avoid the fatigue and especially the chronic fatigue, rest pauses must be taken. Frequent short rest periods reduce cumulative fatigue better than a few long breaks.