Slide 1

The Onset and Magnitude of Cardiovascular Drift Depend on

Exercise Intensity in Runnersby Jena Winger

A SENIOR PROJECT Presented to the Department of Exercise Science

and the College of Liberal Artsin partial fulfillment of the requirements

for the degree of Bachelor of Arts

March 17, 2009

Slide 2

130

140

150

160

170

180

190

5 10 15 20 25 30 35 40 45 50 55 60Time (min)

Hea

rt R

ate

(bpm

)

Cardiovascular Drift

∆=10BPM

Slide 3

Causes of CVdrift

Cardiovascular drift

↑ Core Temp Sympathetic Stimulation

↓ Muscle Contractility

↓ Force of Contraction

Thermoregulation

↑ Cutaneous Blood FlowSweating

Dehydration

↓ Plasma Volume

↓ Total Blood Volume

↓ End-Diastolic Volume

↓ Stroke Volume

↑ Heart Rate

↓ Central Blood Volume

↓ Ventricular filling time

Slide 4

Is there an energy cost associated with cardiovascular drift and if so, can it be

quantified?

Slide 5

What has been done?

• Lajoie, C., Laurencelle, L., Trudeau, F. (2000)• Observed drift in all but blood lactate• Lactate threshold fixed @ 4mmol/L

Slide 6

Slide 7

Purpose

Determine the energy cost associated with CVdrift in runners by examining HR, VO2, and

BL at three different exercise intensities: at, just above, and just below MLSS.

Slide 8

Hypothesis

Minor differences in exercise intensity would result in a significantly different onset and

magnitude of both CVdrift and VO2drift

Slide 9

Method

• Participants• VO2max test

• Lactate Threshold test• 3 Steady State exercise tests• Statistical Analysis

Slide 10

Participants

N= 10

Age 40.30 ± 8.27

Years Training 9.25 ± 6.97

Height (m) 1.76 ± 0.07

Weight (kg) 71.29 ± 10.76

VO2max (ml/kg/min) 55.96 ± 5.48

Hrmax (bpm) 181.9 ± 12.20

BL @ MLSS (mM/L) 2.29 ±-.95

95% MLSS (MPH) 8.44 ± 0.61

100% MLSS (MPH) 8.89 ± 0.66

105% MLSS (MPH) 9.35 ± 0.70

N= 5

Age 19.6 ± 1.14

Years Training 6.4 ± 1.14

Height (m) 1.79 ± 0.05

Weight (kg) 66.30 ± 4.44

VO2max (ml/kg/min) 67.35 ± 2.69

Hrmax (bpm) 193.20 ± 5.76

BL @ MLSS (mM/L) 1.94 ± 0.59

MLSS – 0.02 (MPH) 9.52 ± 0.61

MLSS (MPH) 9.72 ± 0.61

MLSS + 0.02 (MPH) 9.92 ± 0.61

SCRP ResearchCommunity Recreational Runners

Thesis ResearchMen’s Cross Country Team

Slide 11

– Criteria for valid VO2max test: • HR & VO2 plateau RER> 1.1 and volitional exhaustion

– Self-selected warm up speed– Two minute stages– 1.0-2.0 MPH speed increases to exhaustion– Continuous HR and VO2 collection

– Blood collection @ end of each stage for lactate analysis

VO2max test

Slide 12

Slide 13

– Same warm up pace– Five minute stages– 0.2 to 0.3 MPH (0.09 to 0.13 m/s) speed increases

until threshold is reached– Continuous HR and VO2 collection

– Blood collection @ end of each stage for lactate analysis

Lactate Threshold Test

Slide 14

Slide 15

– 45 minutes at, just above, and just below Lactate Threshold

– Continuous HR and VO2 collection

– Blood collection for lactate analysis every 10 minutes

Statistical Analysis– ANOVA (α=.05)

Prolonged steady-state exercise bouts

Slide 16

Heart Rate

*P = 3.21E-06

Slide 17

Heart Rate

*P = 0.205777

Slide 18*P = 8.42E-13

Oxygen Consumption

Slide 19

Oxygen Consumption

*P = 84.22E-08

Slide 20*P = 0.000124

Blood Lactate

Slide 21

Blood Lactate

*P = 0.013788

Slide 22

Findings

SCRP Research• Significant differences in heart rate, oxygen

consumption, and blood lactate between and within each intensity (p<0.05)

Thesis Research• No significant differences in heart rate• Significant differences in oxygen consumption and

blood lactate (p<0.05)

Slide 23

Issues with data collection

• Variability between and within participants

• Scheduling• Retention

Slide 24

Conclusion

The onset and magnitude of CVdrift is affected by changes in intensity ≤ 0.22 m/s, but is

not affected by changes in exercise intensity ≤0.09 m/s

Slide 25

Future Studies

• Second VO2max test

• Collect RPE and Core Body Temperature data• Larger sample size• Improved compliance

Slide 26

Acknowledgements

• National Science Foundation (CCLI 0511219)• Mary Stuart Rogers Foundation• Gallagher’s Running Team• WU Men’s Cross Country Team• Kristi Murphy, Kelsey Nakata, and Doug Rice• Stasinos Stavrianeas

Slide 27

Questions?