Award Date


Degree Type


Degree Name

Master of Science (MS)


Kinesiology and Nutrition Sciences

First Committee Member

James Navalta

Second Committee Member

Richard Tandy

Third Committee Member

John C. Young

Fourth Committee Member

Szu-Ping Lee

Number of Pages



The purpose of this study was to investigate whether the Hexoskin shirt and the wrist worn Fitbit Flex activity monitor were both valid and reliable for the physiological functions they were designed to monitor. Heart rate (beats·min-1), respiratory rate (breaths·min-1), step count, and energy expenditure results were collected for the Hexoskin. Step count and energy expenditure were collected for the Fitbit Flex. 49 adolescent participants performed a walking treadmill protocol at 1.5 mph, 2.5 mph, and 3.5 mph for 3 minutes at each speed. 46 subjects returned to perform the same protocol a second time. 31 of the participants were used to determine reliability. Each trial required the participants to walk while wearing a Hexoskin shirt, a Fitbit Flex on their right wrist, a Polar T-31 heart rate monitor, and to be monitored by an Applied Electrochemistry Moxus Metabolic System.

Hexoskin heart rate correlation was inconsistent between the two protocols with some minutes/stages being highly related in one protocol and not in the other. A number of stages showed significant differences in the mean values. Interclass correlation was acceptable for half of the measurements compared

Hexoskin respiration rate values were highly correlated for the every minute of the first two stages (1.5 mph and 2.5 mph) but showed variations between protocols in the final (3.5 mph). All but one minute’s heart rate value was significantly underestimated. All stages exhibited high interclass correlation scores.

Hexoskin energy expenditure had no stages that were correlated. However, all stages showed no significant differences though the Hexoskin did slightly overestimated caloric count values. The interclass correlation was acceptable for all stages

Fitbit Flex energy expenditure was not acceptably correlated for any stage, the values were significantly higher than the MOUXS calculated values, and no stage could be considered acceptable for interclass correlation purposes.

Hexoskin step count was highly related only at the 3.5 mph stage. The 1.5 mph and 2.5 mph stages were not correlated and also significantly underestimated the steps taken. Only the 3.5 mph walk could be accepted as reliable.

Fitbit flex step count was not correlated for any stage, the values were significantly lower than the observed count, and no stage could be considered acceptable for interclass correlation.

Overall, the Hexoskin and Fitbit Flex do not appear to be acceptable tools for research purposes.


Exercise; Heart rate monitoring; Patient monitoring – Equipment and supplies; Pedometers


Exercise Science | Kinesiology

File Format


Degree Grantor

University of Nevada, Las Vegas




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