Chester Step Test Norms

International databases relate aerobic capacity scores to age and sex. Females tend to have mean values some 25-30% lower than males. Mean values for aerobic capacity may decline by as much as 5 mlsO2/kg/min for every decade after 20 – hence while 45 mlsO2/ kg/min is around a top average fitness score for a 20-year old, this would represent a very good fitness score for a 40-year old (see Table 1). Note: If the aerobic capacity score is used as a pass/fail benchmark, considerations may have to be given for age and sex – unless the work demands can be validly shown to have a specific aerobic ‘cost’, which may be independent of age and sex.

Aerobic capacity and ‘Anaerobic Threshold’

While aerobic capacity is a good measure of cardio-respiratory fitness, it is not, however, the whole story when examining the ability of a person to sustain physical work. It is not, uncommon to find some older people well able to keep up with the youngsters – whether it be walking in the hills, or in a physically demanding workplace – albeit that their aerobic capacity may be lower. It appears that many of us, as we get older, improve our ability to work for prolonged periods at a higher percentage of our aerobic capacity. So, although regular training may, for some, only minimally increase their aerobic capacity, they improve their ability to work at a higher percentage of their maximum value. This ‘cruising speed’ is often referred to as the ‘anaerobic threshold’ – the point at which increases in ventilation volumes become curvilinear and lactic acid begins to build. The problem with the anaerobic threshold is that it is difficult to measure accurately without analysing respiratory or lactate responses to incremental exercise bouts. This is certainly one explanation for the occasional anomaly – the person who appears to be aerobically fit and has good staying power – but has a relatively – and sometimes surprisingly – low aerobic capacity.  

Table 1. Norms for aerobic capacity (mlsO2/kg/min)

  Male age groups
Fitness Rating 15-19 20-29 30-39 40-49 50-59 60-65
Excellent 60+ 55+ 50+ 46+ 44+ 40+
Good 48-59 44-54 40-49 37-45 35-43 33-39
Average 39-47 35-43 34-39 32-36 29-34 25-32
Below average 30-38 28-34 26-33 25-31 23-28 20-24
Poor <30 <28 <26 <25 <23 <20
Female age groups
15-19 20-29 30-39 40-49 50-59 60-65
55+ 50+ 46+ 43+ 41+ 39+
44-54 40-49 36-45 34-42 33-40 31-38
36-43 32-39 30-35 28-33 26-32 24-30
29-35 27-31 25-29 22-27 21-25 19-23
<29 <27 <25 <22 <21 <19
 
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