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F-63 Thematic Poster - Reliability and Validity of Fitness Testing: JUNE 3, 2011 3: 15 PM - 5: 15 PM: ROOM: 304

K4b2 Validity and Reliability during Fast Outdoor Running


Board #2 3:15 PM - 5:15 PM

Ross, Ramzy; Fudge, Barry; Gibson, Alexander; Ojiambo, Robert; Pitsiladis, Yannis FACSM

Author Information
Medicine & Science in Sports & Exercise: May 2011 - Volume 43 - Issue 5 - p 80
doi: 10.1249/01.MSS.0000402913.38341.ef
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The portable K4b2 (K4b2, COSMED s.r.l., Rome, Italy) was designed to measure breath-by-breath pulmonary gas exchange in the field. K4b2 validity has been confirmed during treadmill running, while during outdoor running the K4b2 systematically underestimated oxygen uptake (VO2) (Fudge et al, MSSE, 2008).

PURPOSE: This study assessed both the validity and reliability of the K4b2 with the introduction of an automated periodical recalibration in an attempt to correct the systematic underestimation in VO2 previously reported.

METHODS: 19 Caucasian endurance trained individuals and 30 adolescents (boys, n=15; girls, n=15) from a rural Nandi primary school in Kenya completed maximal incremental running tests. Tests involved 3 minute exercise bouts at running speeds between 8 to 22 km·hr-1 in 2 km·hr-1 increments. Gas exchange parameters were recorded throughout. The Douglas bag method (DB) was used as the criterion for comparison.

RESULTS: K4b2 measurements were not significantly different for VO2 throughout all submaximal and maximal running speeds when compared to DB: corresponding to a K4b2 mean bias (MB) -31 ml·min-1 with limits of agreement (LOA) -430 to 492 ml·min-1 for all running speeds. K4b2 test-retest reliability was also demonstrated with no significant differences found in all measured gas exchange variables throughout all submaximal and maximal running speeds: corresponding to a K4b2 MB -31 ml·min-1 with LOA -535 to 473 ml·min-1 for all running speeds.

CONCLUSION: As a result of the introduction of an automated calibration, the K4b2 device proved valid and reliable for VO2 during submaximal and maximal running velocities outdoors.

© 2011 American College of Sports Medicine