• Question: Does time of the day affect running speed, by how much and why?

    Asked by nich to Audra, Fiona, Gavin, Justin, Steve on 12 Mar 2012.
    • Photo: Steve Faulkner

      Steve Faulkner answered on 9 Mar 2012:

      The time of day will certainly affect running speed and other measures of performance. Depending on the distance this can equate to a performance change of a few seconds or more! This is due to what is know as circadian variation. There are a number of reasons that cause this including the amount of certain hormones which change throughout the day. Although the difference in speed may not seem huge it is certainly detectable. This is why in the studies I conduct which involve measures of performance (cycling or running) I ensure that athlete’s come to the lab at the same time of day for each of their tests to minimize any variation due to the time of day. However, many people find that there prefer to do “fast training” at a certain time of day, and this may not just be due to physiological differences. For instance I know of some athletes who “can’t run fast in the mornings.” This is likely to lead to a belief that they can not do so rather than underpin a physiological difference and as such can lead to a reduction in running speed because they believe (rightly or wrongly) that the mornings make them run slow! IN psychology this is know as a “self-fulfilling prophecy” where a belief will lead to an actual behaviour outcome, even though that belief may not be true.

    • Photo: Fiona Hatch

      Fiona Hatch answered on 9 Mar 2012:

      Yes it can. This can be for many reasons, probably too many to describe but I can summarise a few.

      Your body runs on its own inner clock, this clock works with the Sun and time of day. So in the morning you wake up because your body clock tells you it is time (there is probably an alarm clock or your parents waking you up too) but your body will wake you up eventually.

      In the evening your body is getting ready to sleep and so it will make you tired and cause you to become sleepy and then you’ll sleep for the night and be ready for the morning again. All this is controlled by hormones.

      So if we imagine you go running in the morning, your body has just woken up which might affect how fast you can run. If you were to run before bed, your body is releasing a hormone called melatonin, which makes your sleepy, so if you were to go running then, you would probably be slower than in the morning. During the day (11am – 4pm for example) your body would be at it’s most awake and would be ready for you to do anything you wanted! So during the day your body would be able to run faster.

      Linked with time of day is also the time you would eat at. If the body has food then it will be able to produce more energy and allow you to run faster.

      Also involved is what the body and brain is use to doing. If you are use to playing sports every afternoon, then that would be normal for you. But if I suddenly woke you up at 4am and asked you to play sports then you would probably not be as good ( you would also hate me!). But if I asked you to play in the afternoon then you would find that normal and would be able to do your best. Though if your friend always plays sports at 4am, then if I asked him/her to play with you in the afternoon, he/she would not be as good as you.

      The more you exercise in the afternoon the more you will then start to believe you are better at sports in the afternoon than any time of day (this links on to the psychological behaviour Steve mentions).

      I cannot give you an exact answer of how much speed you can gain, but I will say that time of day would affect it by a lot.

    • Photo: Justin Lawley

      Justin Lawley answered on 12 Mar 2012:

      This is a great question and awesome answers. I attended a public lecture last year in oxford about circadian rhythms. Its amazing how we follow a sleep-wake cycle every day. Interestingly, there are cells in your eye that sense the blue light in the sky and regulate these cycles. How amazing is it that the sky is blue in the day and not at night and you just happen to have a cell in your eye that can detect this. Furthermore, it was also discovered that every cell has a its own 24hour clock. I think I remember Dr Foster saying that an olympic swimmer would be 2.7 seconds faster depending on the time of day. Which is the difference between coming first and very last. Also maintaining your normal sleep wake cycle is important for athletes who travel across the world to compete.

Comments

  • Photo: Fiona

    Fiona commented on :

    Lol Justin, I attended the same lecture! Small world in science. It was a very interesting talk. The society filmed the talk and said it should be uploaded, so if I find the link I’ll paste it here for you to watch it if you’re interested.