"Untrained individuals" refers to people who have not received formal or specific instruction or education in a particular skill or area. These individuals lack the necessary knowledge and expertise in that field. Full definition
They found that the cross-sectional area of the calf muscles in untrained individuals was 39.9 cm2 while the cross-sectional area of the calf muscles in trained individuals was 44.7 cm2. (strengthandconditioningresearch.com)
That's on the low side, but not unusual for untrained individuals. (ergo-log.com)
The procedure is less time and cost - intensive than angling, and the samples can even be drawn by untrained individuals. (sciencedaily.com)