JC's Musings

Better Assessment

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Understanding how you eliminate the “noise” in your assessments, will go a long way to truly help you understand the effects of your training and having confidence in any claims you make. This was the topic of a recent conversation with Alex Ross, Performance and Sport Science Manager at the New York Mets.

Did you know that the time of day when testing is conducted may influence your results due to “time of day” effects i.e. diurnal variation? Force, velocity and power output may be up to ~6.0% higher in the afternoon than the morning.

So why is that? The most common hypothesis is that the differences are due to diurnal variation in whole body temperature that affects explosive power output and other variables. We showed this in 2011 when we compared loaded countermovement jump variables from an 8.00 am session to a 4.00 pm session, the results 2-6% greater in the afternoon. However, when we did an extended warm-up in the morning there were no substantial differences between sessions.

So the take home message, conduct your performance testing at the same time of the day to help control for diurnal variations in body temperature.