Effect of aerobic fitness on the validity of the Calera Research™ sensor to estimate core temperature during exercise
Bibliographic record
Abstract
The Calera Research™ is a heat flux device advertised to estimate core temperature (Tc) during physical activity and is widely used by athletes in various sport disciplines. The device estimates Tc from skin temperature, heart rate, and heat flux, outcomes that can be affected by aerobic fitness. However, there is a relatively small body of literature exploring its validity and, specifically, how the device bias may be influenced by aerobic fitness. The objective of this study was to assess the validity of the Calera Research™ sensor compared with telemetric ingestible pills for estimating Tc and to determine whether aerobic fitness impacts accuracy. Twenty participants (10 females) performed a cycling-based ramp-incremental exercise test to volitional exhaustion in a temperature controlled environment (22 °C) during which Tc was measured directly from ingested pills (eCelsius performance system) and by the Calera device. Compared to the ingestible telemetric pills, the Calera device exhibited lower Tc values (95%CI[-0.2, -0.3 °C], p < 0.001) with an intraclass correlation of 0.47 and a bias of −0.3 ± 0.2 °C. Participants were divided into two groups (10 participants at each group) based on peak oxygen uptake ( V ˙ O 2peak ) (HL: high aerobic; LL: lower aerobic fitness). Throughout ramp-incremental exercise, HL had a lower heart rate (p < 0.001 and η 2 = 0.10; 95%CI[0.1, 17.2 bits/min]) and Tc measured by the ingestible pills (p < 0.001 and η 2 < 0.01, 95%CI[0.1, 0.3 °C]). However, there were no-between group differences for skin temperature and intraclass correlation values and bias were also similar. In conclusion, the estimation of Tc by Calera Research™ underestimated Tc by approximately 0.3 °C in a moderate thermal environment, but the intensity-dependent profile was similar to that of the ingestible pill method and was unaffected by aerobic fitness differences. • The Calera consistently underestimated core temperature (by ∼0.3ᵒC). • The underestimation magnitude increased in people with higher core temperature. • This core temperature estimation was not affected by the aerobic fitness status.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.002 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".