Abstract. New technologies afford convenient modalities for skin temperature (T SKIN ) measurement, notably involving wireless telemetry and non-contact infrared thermometry. The purpose of this study was to investigate the validity and reliability of skin temperature measurements using a telemetry thermistor system (TT) and thermal camera (TC) during exercise in a hot environment. Each system was compared against a certified thermocouple, measuring the surface temperature of a metal block in a thermostatically controlled waterbath. Fourteen recreational athletes completed two incremental running tests, separated by one week. Skin temperatures were measured simultaneously with TT and TC compared against a hard-wired thermistor system (HW) throughout rest and exercise. Post hoc calibration based on waterbath results displayed good validity for TT (mean bias [MB] = -0.18°C, typical error [TE] = 0.18°C) and reliability (MB = -0.05°C, TE = 0.31°C) throughout rest and exercise. Poor validity (MB = -1.4°C, TE = 0.35°C) and reliability (MB = -0.65°C, TE = 0.52°C) was observed for TC, suggesting it may be best suited to controlled, static situations. These findings indicate TT systems provide a convenient, valid and reliable alternative to HW, useful for measurements in the field where traditional methods may be impractical.

Post-exercise cardiac troponin (cTn) elevation is a recognised phenomenon which historically has been detected using standard sensitivity assays. More recently high-sensitivity assays have been developed and are now the gold standard for detection of cTn in the clinical setting. Although the assay's enhanced sensitivity confers benefits it has created new challenges for clinicians. By evaluating the change in cTn values over time, taking into account biological and analytical variation, the clinician is able to differentiate between a pathological and normal cTn value. As a result, serial cTn testing has become a fundamental component of the clinical assessment of chest pain patients and is included in the most recent definition for myocardial infarction and the latest guidelines for the management of acute coronary syndromes without persistent ST-segment elevation. A review of the cTn kinetics literature demonstrates a pattern of elevation and peak within the first 4 h after exercise dropping within 24 h. In contrast myocardial necrosis demonstrates a later cTn peak with a slower downslope occurring over several days. Understanding cTn kinetics facilitates clinician's decision making when presented with a chest pain patient post-exercise. Furthermore, it helps elucidate the underlying mechanism and establish the clinical significance of post-exercise cTn elevation, which in all other situations confers negative prognostic value. We recommend serial cTn testing in this scenario with a suggested algorithm included in this review.

Twelve males completed three incremental, discontinuous treadmill tests in the heat [31.9(1.0)°C, 61.9(8.9)%] to determine speed at two fixed blood lactate concentrations (2 and 3.5 mmol/L), running economy (RE), and maximum oxygen uptake ( VO 2max ). Trials involved 20 min of either internal cooling (ICE, 7.5 g/kg ice slurry ingestion) or mixed-methods external cooling (EXT, cold towels, forearm immersion, ice vest, and cooling shorts), alongside no intervention (CON). Endurance exercise is underpinned by the ability to transfer chemical energy into a given exercise velocity (Coyle, 1999). The status of this biological process can be assessed using physiological markers such as the lactate thresholds, running economy (RE), and maximum oxygen uptake ( VO 2max ). Under normothermic conditions, when combined with the peak treadmill velocity, these markers have been shown to account for 97.8% of the variation in 16 km run time (McLaughlin et al., 2010). McLaughlin et al. (2010) highlighted that VO 2max accounted for 90.2% of variation in running time in a group with heterogenous VO 2max values. Furthermore, Lorenzo et al. (2011) has shown the lactate turnpoint (LTP) to be a strong predictor of time trial performance in both cold (r = 0.89) and hot (r = 0.87) environments.

CTnT increases above reference limits during a marathon. Magnitude of cTnT rise is related to exercise intensity relative to ventilatory threshold and V˙Omax, but not individuals' absolute cardiopulmonary fitness, training state or running history.

This study investigated the effect of 5 days of controlled short-term heat acclimation (STHA) on the determinants of endurance performance and 5-km performance in runners, relative to the impairment afforded by moderate heat stress. A control group (CON), matched for total work and power output (2.7 W·kg), differentiated thermal and exercise contributions of STHA on exercise performance. Seventeen participants (10 STHA, 7 CON) completed graded exercise tests (GXTs) in cool (13 °C, 50% relative humidity (RH), pre-training) and hot conditions (32 °C, 60% RH, pre- and post-training), as well as 5-km time trials (TTs) in the heat, pre- and post-training. STHA reduced resting (p = 0.01) and exercising (p = 0.04) core temperature alongside a smaller change in thermal sensation (p = 0.04). Both groups improved the lactate threshold (LT, p = 0.021), lactate turnpoint (LTP, p = 0.005) and velocity at maximal oxygen consumption (vV̇O; p = 0.031) similarly. Statistical differences between training methods were observed in TT performance (STHA, -6.2(5.5)%; CON, -0.6(1.7)%, p = 0.029) and total running time during the GXT (STHA, +20.8(12.7)%; CON, +9.8(1.2)%, p = 0.006). There were large mean differences in change in maximal oxygen consumption between STHA +4.0(2.2) mL·kg·min (7.3(4.0)%) and CON +1.9(3.7) mL·kg·min (3.8(7.2)%). Running economy (RE) deteriorated following both training programmes (p = 0.008). Similarly, RE was impaired in the cool GXT, relative to the hot GXT (p = 0.004). STHA improved endurance running performance in comparison with work-matched normothermic training, despite equality of adaptation for typical determinants of performance (LT, LTP, vV̇O). Accordingly, these data highlight the ergogenic effect of STHA, potentially via greater improvements in maximal oxygen consumption and specific thermoregulatory and associated thermal perception adaptations absent in normothermic training.