What is the criterion measure of cardiorespiratory fitness?

Maximal oxygen consumption (VO2max).

What is VO2max?

maximal amount of oxygen that the body can intake, transport, and utilize; Depends on cardiac output and arteriovenous oxygen difference; Fick eqn: VO2 = Q * (a-v)O2diff; VO2max: maximal Q * maximal (a-v)O2diff; Commonly reported in relative units (mL·kg−1·min−1), for comparison to norms and others of different body sizes; Can be in absolute units also (L/min).

Why is VO2max important for health?

Low aerobic fitness is associated with increased mortality and cardiovascular disease; American Heart Association recognizes aerobic fitness as a stronger predictor of mortality than other risk factors; Considered a vital sign.

How is VO2max measured?

Maximal graded exercise test (GXT) – directly measure VO2 while subject exercises until maximal exertion; Commonly referred to as symptom-limited graded exercise test (SL-GXT); Submaximal GXT – predetermined termination point; VO2max estimated from HR response to exercise; Field Tests – can be maximal or submaximal; VO2max estimated by performance and/or HR response to exercise.

What are maximal vs submaximal tests?

Maximal: Pros: very accurate, very sensitive; Cons: potentially dangerous; expensive; time-consuming; Submaximal: Pros: less risk, cheaper, less time consuming; Cons: less accurate; less sensitive.

What are common modalities?

Treadmill: Graded max/submax; Cycle ergometer: Graded max/submax; Step testing: Post-exer HR; Field Tests: Walking/running a distance or for a period of time.

What are common protocols?

Treadmill: Graded: Bruce, Modified-Bruce, Balke, Naughton; Bike: Graded: YMCA submax, individualized protocols; Astrand-Ryhming test; Field Tests: 1-mile walk, 1.5 mile run, 12-min run, 6-min walk; Step Tests: Queens college step test; Considerations when choosing a modality/designing a protocol?

What are characteristics of Bruce Protocol?

Speed (mph): 1.7, 2.5, 3.4, 4.2, 5.0, 5.5; Grade (%): 10, 12, 14, 16, 18, 20; Duration: 3 min per stage.

What are characteristics of Modified-Bruce Protocol?

Speed (mph): 1.7, 1.7, 1.7, 2.5, 3.4, 4.2, 5.0, 5.5; Grade (%): 0, 5, 10, 12, 14, 16, 18, 20; Duration: 3 min per stage (“Optional”).

What are characteristics of Balke-Ware Protocol?

Speed: 3.3 mph constant; Grade increases 1% each minute; Duration: 1 min per stage.

What are other treadmill protocols?

Naughton: 2 or 3 mph; Grade increases either 3.5 or 2.5 every 2 minutes; Ramp: variable; Frequent, small increases in intensity; Examples: 1% increase in grade every 30 sec at a set speed; 0.5% increase in grade every 15 sec.

What are cycle ergometer protocols?

There are not standardized maximal cycle protocols, as there are for the treadmill; Protocols are often designed based on the subject’s abilities; Example: increase of 150 kg•m•min-1 (~25 Watts) every 2-3 min; increase of 1 Watt every 6 sec (ramp); YMCA submaximal exercise test.

What measurements are taken during GXT?

Heart rate; Blood Pressure; Rating of Perceived Exertion (RPE); EKG (if necessary); Expired gases & ventilatory responses (if necessary); VO2, VCO2, VE, RER; Angina scale (if necessary); Dyspnea scale (if necessary); Claudication scale (if necessary); Oxygen saturation (if necessary).

What are Borg’s RPE scales?

Borg’s 6-20 RPE scale: Correlates well with HR and VO2; limited use in statistical analyses; Borg’s Category-Ratio scale (CR10): Does not correlate well with HR & VO2; useful in statistical analyses (e.g. a value of 8 represents a effort 2x as hard as 4).

What are general procedures before a GXT?

Select protocol; BP/HR/EKG in the exercise position; Familiarize subject with exercise modality; Adjust bike settings if necessary; 25-degree knee bend; Explain RPE scale; Further pretest instructions related to testing procedures; Baseline gas exchange (if collecting VO2); 2-3 min warm-up.

What are procedures during a GXT?

HR: each min; BP: 1x/stage (last min); RPE: each stage; Signs/symptoms: continuously monitor; record as necessary; Other variables: EKG: continuously; recorded last 15 sec of each stage; Expired gases & ventilation: continuous; Other subjective scales: record as necessary; If submaximal GXT: stages should be 3 minutes (HR measured at end of 2nd and 3rd min); HR must be within 5 bpm within a stage; if not, extend stage 1 min.

What are procedures after a GXT?

Active cool-down (workload of 1st stage); Passive supine cool-down if warranted; Continue to monitor HR/BP during cool-down for >5 min; Maybe longer if symptoms/abnormal responses occur; BP/HR should stabilize and return to near-baseline levels, but may not return to pre-exercise levels; HR: recorded at end of each minute; BP: recorded immediately post-exercise and every 2 min; RPE: recorded at peak exercise; not in recovery; Signs/symptoms: continue to monitor; If necessary: EKG: recorded immediately post-exercise, last 15 sec of 1st min of recovery, and every 2 min after.

How is VO2max predicted from submaximal tests?

Submaximal GXTs have a predetermined termination point; Healthy: ~85% of predicted max HR (70% HRR); HR increases linearly with intensity; HRmax can be estimated; Extrapolate HR from submaximal workloads to estimate maximal workload.

What is the equation for estimating HRmax?

HRmax = 220-age; easy to use; often underestimates HR in <40 yrs of age; often overestimates HR in >40 yrs of age; Other equations.

How is VO2 estimated from workload?

Metabolic equations (Appendix C; page 609); Established equations for: Walking; Running; Leg ergometry; Arm ergometry; Stepping; Normative values of VO2max can be found on pages 91-94.

What are assumptions of a submaximal GXT?

Steady state HR is obtained at each workload; Need 2 HRs within 5 bpm at each stage; Linear relationship between HR and workload; Max workload is indicative of VO2max; Age-predicted max HR is correct; VO2 at a given workload is the same for everyone (assumes metabolic equations are accurate); Subject is not on medications that influence HR.

What is the Astrand-Rhyming Cycle Test?

Single-stage, 6-min test; Use a predetermined workload based on sex and fitness; Obtain 2 steady state HRs during minutes 5-6, between 125-170 bpm; Use nomogram to estimate VO2max, using correction factor.

What is the Queens College Step Test?

16.25 in (41.25 cm) step height; Stepping rate: males: 24 steps/min; female: 22 steps/min; Recovery HR is taken; 15-sec HR; 5 seconds after test completion; Males: VO2max = 111.33-(0.42*HR); Females: VO2max = 65.81-(0.1847*HR).

What are field test VO2max equations?

1.5 mile run: VO2max = 3.5 + 483/time (min); 12-min run: VO2max = (Distance (meters) – 504.9) / 44.73; Rockport 1-mile Walking Test: VO2max = 132.853 – (0.1692*body mass in kg) – (0.3877*age) + (6.315*sex) – (3.2649*time in min) – (0.1565*HR); [For sex, female: 0; male: 1].

What are risks of exercise testing?

Peak Exercise Tests or Symptom-limited Graded Exercise tests; *includes patients with disease; Risk for all CV events: 0.06%.