Reaction Time: A potential indicator of fatigue

Athlete monitoring is a hot topic in the world of strength and conditioning these days. A good athlete monitoring program will help reduce injury and keep athletes performing at a high level. Coaches have a vast selection of tools to choose from for monitoring their athletes. Unfortunately, many monitoring tools come with a very high price tag. In addition, data collection, interpretation and visualization may be a very time consuming task for busy strength coaches. Tools that are affordable, user-friendly, non-invasive and scientifically validated are desirable.

A potentially worthwhile tool for monitoring central nervous system status is a simple reaction time test. This meets the above criteria of being affordable, user-friendly and non-invasive, however, is it scientifically validated? The reaction test was theorized to reflect fatigue in athletes because of the common symptoms seen between chronic fatigue syndrome, major depression and the overtraining syndrome (Nederhof et al. 2006). Patients with chronic fatigue and major depression display psychomotor slowness (slower reaction time) and thus it was hypothesized that overtrained or fatigued athletes may also display decreased psychomotor speed.

To test this hypothesis Nederhof and colleagues (2007), evaluated reaction time at baseline, during a two week overload and following a two week taper in a group of trained cyclists and control. During the overload, 5 athletes were considered functionally overreached (decreased performance, increased fatigue) while the others were considered well trained. The control group and the well trained group improved their reaction time at each test. The functionally overreached group however showed increased (slower) reaction time after the overload period but improved reaction time beyond baseline values after the taper.

A separate study in trained cyclists by Rietjans et al (2005), also determined that reaction time suffered in response to overload training. The authors stated; “The most sensitive parameters for detecting overreaching are reaction time performance (indicative for cognitive brain functioning), RPE and to a lesser extend the shortened POMS (profile of mood states). This strongly suggests that central fatigue precedes peripheral fatigue. All other systems, including the neuro-endocrine, are more robust and react most likely at a later stage in exhaustive training periods.”

There’s an app for that! A quick search through your android and apple app store and you’ll find some very inexpensive or even free reaction time apps. Perhaps it’s worth experimenting with a handful of athletes throughout a pre-season training camp. How do reaction times during heavy loading compare to baseline values? It should be noted that the studies discussed in this post did not use smart phone apps. However, some personal experimentation may be worthwhile.

 

References:

Nederhof, E., et al. (2006) Psychomotor speed: possibly a new marker for overtraining syndrome. Sports Medicine, 36(10): 817-28.

Nederhof, E., Lemmink, K., Zwerver., J. & Mulder, T. (2007) The effect of high load training on psychomotor speed. International Journal of Sports Medicine, 28: 595-601.

Rietjans, GJ., et al. (2005) Physiological, biochemical and psychological markers of strenuous training induced fatigue. International Journal of Sports Medicine, 26(1): 16-26.