Insulated skin temperature as a measure of core body temperature for individuals wearing CBRN protective clothing.

This study assessed the validity of insulated skin temperature (Tis) to predict rectal temperature (Tre) for use as a non-invasive measurement of thermal strain to reduce the risk of heat illness for emergency service personnel. Volunteers from the Police, Fire and Rescue, and Ambulance Services performed role-related tasks in hot (30 °C) and neutral (18 °C) conditions, wearing service specific personal protective equipment. Insulated skin temperature and micro climate temperature (Tmc) predicted Tre with an adjusted r(2) = 0.87 and standard error of the estimate (SEE) of 0.19 °C. A bootstrap validation of the equation resulted in an adjusted r(2) = 0.85 and SEE = 0.20 °C. Taking into account the 0.20 °C error, the prediction of Tre resulted in a sensitivity and specificity of 100% and 91%, respectively. Insulated skin temperature and Tmc can be used in a model to predict Tre in emergency service personnel wearing CBRN protective clothing with an SEE of 0.2 °C. However, the model is only valid for Tis over 36.5 °C, above which thermal stability is reached between the core and the skin.

Reliability and validity of the 3DNX accelerometer during mechanical and human treadmill exercise testing.

OBJECTIVE: This study aimed to assess the validity and reliability of the 3DNX triaxial accelerometer in a laboratory and mechanical setting. METHODS: Experiment 1: A total of 10 units were fixed to a Multi-axis shaker table. A schedule comprising a range of accelerations was repeated on two occasions along each of the three measurement axes. Experiment 2: A total of 11 recreationally active individuals completed a treadmill protocol (4-20 km hr(-1)) on two occasions. Two 3DNX accelerometers were secured to the lower back, logging data every 5 s. Oxygen uptake was measured using the Douglas Bag technique. Reliability inter- and intra-units were assessed using a combination of limits of agreement (LoA), coefficient of variation (CV) and intra-class correlation coefficient (ICC). Validity was assessed using simple linear regression. All data are expressed in counts per 5 s (counts 5 s(-1)). RESULTS: Experiment 1: CV(intra) ranged from 0.0 to 8.9% in all axes. The absolute bias±95% LoA values were all below four counts 5 s(-1). CV(inter) did not rise above 4.5%. ICCs were 1.0 for all stages in all axes. The relationship between 3DNX counts and acceleration yielded an R(2) value of 0.99 and a standard error of the estimate (SEE) of six counts 5 s(-1). Experiment 2: CV(inter) ranged from 7.7 to 16.0% for trial 1 and from 7.7 to 16.2% for trial 2. ICCs between units ranged from 0.95 to 1.00 for trial 1 and from 0.90 to 0.99 for trial 2. Mean ratio bias±95% LoA values for intra-unit and inter-unit reliability were -0.7% (P>0.05)±12.4% and 0.4% (P>0.05)±5.6%, respectively. The relationship between VO(2) and 3DNX counts for walking and running was linear (R(2)=0.65, SEE=1.42 ml kg(-1) min(-1); R(2)=0.62, SEE=3.63 ml kg(-1) min(-1)). CONCLUSION: The 3DNX accelerometer is a reliable and valid device for measuring acceleration in a mechanical setting and during human treadmill exercise.