1. The effects of partial sleep restriction on biomechanical, physiological and perceptual responses during an early morning cycling time trial
Dale Edwards; Cathy Munro; Travis Steenkamp;
Dr Jonathan Davy
Department of Human Kinetics and Ergonomics
Rhodes University, Grahamstown

2. Background Effective growth Energy conservation Recovery
7-9 hours (Mignot, 2008)
SLEEP LOSS
Mood
Cognitive performance

3. Background and problem identification
What about athletic performance?
Sleep loss before a competition is a common problem among athletes
performance but the effect on athletic performance is still unclear.
Sleep loss before a competition is a common problem among athletes
Previous research has focused on total sleep deprivation (24 hours or more)
The effect of partial sleep restriction (less than 7 hours) on physical endurance performance remains poorly understood.
Total sleep deprivation (24 hours or more)- Most research
Partial sleep restriction (less than 6 hours)- Limited research

4. Methodology – Experimental Design
Sleep restricted
Normal sleep
4 hours time in bed
Laboratory
Bed: 02h00 or 02h45
Wake: 06h00 or 06h45
Normal sleep (7 – 9 hrs)
Home
Bed ≈ 22h00 to 23h00
Wake: 06h00 or 06h45
Cycling time trial
@06h30 or 07h15
Order randomised
5 – 7 day wash out

5. Cycling protocol and dependent variables
16.1km time trial (Atkinson & Brunskill, 2000)
Air resistance relative to BW
Blinded except for distance covered
Maximal effort required
Time
Power output
Heart rate
Central RPE
Average every 2km
Average every 2km
Taken every 2km

6. Participants and experimental procedure
13 participants (5 female and 8 male); age range18-25
Uninjured, non-smoking, no sleep disorders, oral contraceptives (Females)
Sleep restricted condition = entered lab at 00h00
Recruit, consent habituate
Testing session 1
Testing session 2
Fasted
5 min warm up
Power output, HR, RPE taken every 2km
Resistance setting
16.1 km practise
Female participant characteristics: age 22yrs±1.36; mass 56.5kg±6.74; height 159.8cm±6.78
Male participant characteristics: age 22yrs±1; mass 79kg±8; height 177cm±7

7. Results: Time to completion
Condition effect: p=0.09; Sex effect: p<0.01; Condition*Sex: p=0.58
* (p<0.01
Figure 1: Mean time to completion for both conditions (Error bars denote 95% CI)
Figure 2: Mean time to completion by sex for both conditions (Error bars denote 95% CI)

8. Time to completion

9. Results: Power output End spurt
Condition effect: p=0.09; Distance: p<0.01; Sex effect: p<0.01; Condition*Distance: p=0.98
End spurt
Figure 3: Mean power output for both conditions over the time trial (Error bars denote 95% CI)

10. Results: Heart rate Increased steadily No steady state reached
Condition effect: p=0.34; Distance: p<0.01; Sex effect: p=0.08; Condition*Distance: p=0.72
Increased steadily
No steady state reached
Figure 4: Mean heart rate for both conditions over the time trial (Error bars denote 95% CI)

11. Results: Ratings of perceived exertion
Condition effect: p=0.67; Distance: p<0.01; Sex effect: p=0.23; Condition*Distance: p=0.85
Increased steadily
Figure 5: Mean RPE for both conditions over the time trial (Error bars denote 95% CI)

12. Discussion
Sleep restriction of 4 hours enough to cause performance decrements?
Adapted from Steenekamp & Davy (2014)
Used fixed pace protocol
4 hours partial sleep restriction
Sleep restriction as opposed to fragmented sleep
16.1 km time trial intensity and duration?

13. Limitations Small sample size (n=13) Access to well trained cyclists
Student population
Chronotype was not accounted for

14. Recommendations Exploring boundaries of sleep restriction and exercise
Sleep fragmentation
Chronotype
Individual data

15. Conclusion
Current findings suggest that partial sleep deprivation of up 4 hours has no significant influence on biomechanical, physiological and perceptual responses during a cycling time trial.
However performance is meaningful in the context of cycling.
Methodological inconsistencies within previous literature make it challenging to draw conclusions.
More research needed.
These finding should be seen in light of the limitations of this study.

16. Thank you
Rhodes Travel Grant

17. Thank you