Why a total agility time can mislead you

An agility test gives you one number, and most of that number is straight running. In the study that introduced the deficit, seventeen cricketers ran the 505 agility test and a thirty-metre sprint, and their total 505 times tracked their sprint times closely while the deficit did not track sprint speed at all. Five of the seventeen were ranked differently for agility once the deficit was used instead of the raw time. So a quick player can look sharp on total time while turning poorly, and the raw test never tells you which one you are looking at.

How it is calculated

Subtract your straight-sprint result over a set distance from your result in a change-of-direction test covering the same distance, and what is left is the cost of the turns. The original version compared 505 time against a ten-metre split from a thirty-metre sprint. A squad of twenty-four Brazilian national-team rugby players ran the same logic across three tests, setting the Pro-agility and the Zig-zag against a twenty-metre sprint and the L-drill against thirty metres. The Pro-agility packs two hard turns into twenty metres: you sprint five metres, turn one hundred and eighty degrees, run ten metres back, turn again and finish through the gate.

What national-team rugby players showed

• Backs beat forwards in every change-of-direction test in the squad of twenty-four, but the deficit itself did not differ between positions, so position alone does not tell you who turns well.
• When the same squad was split by sprint speed instead, the faster half posted bigger deficits in all three tests, so the quickest players were the least efficient turners.
• In a second national-team group of eleven, the players carrying more sprint momentum had bigger deficits, and the gap was widest in the tests with the sharpest turns.
• The players with bigger deficits also ran their turns with more trunk and knee bend, a pattern the testers read as struggling to brake from the speeds they arrived with.