Recent technology has included development of ingestible pills and vests designed to monitor core and skin body temperatures. If accurate, they can be ideal in many field settings. However, little research has been performed to demonstrate the accuracy (validity) of this new technology.
PURPOSE: We compared these new technologies with traditional modalities during 60 min of continuous cycle ergometer exercise at room (20o C) temperature.
METHODS: Study participants included a convenience sample (N=18, 14 female, age:23.8±3.4 yr, wt: 70.4±11.6 kg, ht: 175.5±9.3 cm). Intensity for the first 30 min was set at a Power (watts, W) corresponding to individual participant RPE values of 12-13. Intensity increased to an RPE of 15-16 for the final 30 min of cycling, and W were adjusted accordingly. Heart rate (HR) was measured continuously (Polar). Core temperature was measured via a rectal (PROBE-C) thermistor and an ingestible pill (PILL). Skin temperature (PROBE-S) was measured at the arm, chest, thigh, and calf, and a mean value was calculated (Ramanathan, 1964). Core and skin temps were also estimated from a sensor electronics module located in a vest (VEST, Equivital) worn by each participant. Vest temperatures were calculated according to equations developed previously (Buller et al., 2013). Repeated measures ANOVA, Pearson correlations, and dependent t-tests were used to examine relationships among the various temperature measurement modalities (Alpha = p<0.05).
RESULTS: HR averaged 125±25 and 151±18 b/min for the first and second 30 min of exercise, respectively. Likewise, Power averaged 81±22 and 97±22 W. While core temperatures were nearly identical at onset of exercise (˜37.3o C), the three modalities differed after 60 min of cycling (PROBE-C; 37.9±0.8, PILL; 38.3±0.3, VEST; 38.6±0.4o C (p<0.05). Skin temperatures differed between PROBE-S and VEST at both beginning (31.2± 1.1 vs 33.8±1.2o C) and end (32.9± 1.5 vs 37.0±0.6o C) of exercise (p<0.01). Correlations among the various modalities were significant (p<0.05) and ranged from R=0.51 - 0.77, but did not differ from each other.
CONCLUSION: The major study finding was that the vest estimated higher core and skin temperatures during exercise compared to traditional temperature measuring devices, overestimating work intensity at study ambient conditions.