Week 6 - Dallas Bedrest study Flashcards
What did this Dallas Bedrest study seek to investigate?
the influence of detraining followed by training on cardiovascular function
What was the protocol for the study?
5 study participants
20 days bed-rest followed by 50 days training.
- 2 x daily Mon-Fri. 1 x Sat
- Continuous exercise 2.5 - 7 miles running
- Interval training 2-5 min running at near VO2max
What happened to participants V02max with 20 days of bed-rest and 50 days training?
20days bed-rest: decreases in v02max as they began to lose the ability to take up and use oxygen.
50 days training: returned to resting levels and some participants vo2max went above their pre bed-rest values.
What participants saw the greatest improvement in their V02max during the training stage of the study?
The unfit/sedentary participants - some had a v02max greater than their pre bed-rest value.
What is Ficks equation?
Oxygen consumption = cardiac output X a-vo2 difference
How did this study impact cardiac rehabilitation?
Rather than prescribing bed rest, cardiac rehabilitation now involves exercise rehabilitation when safe to do so.
Following the training, how did participants HR, a-vO2 difference, CO and SV compared to after bed-rest?
HR lower at any given workload
CO + SV greater
a-vO2 difference increases sooner with BR
What happened to SV after training? How does this compare to before the study?
SV improved with training and there is a linear increase in stroke volume with oxygen consumption.
This differs to before the study where SV starts to plateau at around 40% of their V02max. Therefore, you get a much greater cardiac output relative to control and bed-rest period.
What happened to a-vo2 difference after training?
a-vo2 difference capacity was greater with training compared to control and bed-rest
Why is there a higher oxygen uptake when sedentary (control) compared to after bed-rest? How can we explain the further increases in oxygen uptake after training?
Sedentary had higher oxygen uptake due to an increase maximal cardiac output relative to after-bed rest, caused by changes in SV (huge decrease after bed-rest).
Further increases with training is due to increase in cardiac output, caused by increased SV and changes in a-vo2 difference capacity.