The Impact of an Ice Slurry-Induced Gastrointestinal Heat Sink on Gastrointestinal and Rectal Temperatures Following Exercise

Abstract

Gastrointestinal temperature (Tgint) measurement with a telemetric pill (TP) is increasingly used in exercise science. Contact of cool water with a TP invalidates Tgint assessment. However, what effect a heat sink created in the proximity of a TP may have on the assessment of Tgint remains unknown. We examined the impact of an ice slurry-induced heat sink on Tgint and rectal temperature (Trec) following exercise. After 20 min of seating (20–22 °C, 25–40% relative humidity (RH)), 11 men completed two intersperse exercise periods (31–32 °C, 35% RH) at 75–80% of estimated maximal heart rate until a Trec increase of 1 °C above baseline level. Following the first exercise period, participants were seated for 45 min and ingested 7.5 g·kg−1 of thermoneutral water, whereas, following the second period, they ingested 7.5 g·kg−1 of ice slurry. Both Tgint and Trec were measured continuously. The TPs were swallowed 10 h prior to the experiments. A bias ≤0.27 °C was taken as an indication that Tgint and Trec provided similar core temperature indices. Mean biases and 95% limits of agreement during passive sitting, first exercise, water ingestion, second exercise, and ice slurry ingestion periods were 0.16 ± 0.53, 0.13 ± 0.41, 0.21 ± 0.70, 0.17 ± 0.50, and 0.18 ± 0.66 °C, respectively. The rates of decrease in Tgint and Trec did not differ between the water and ice slurry ingestion periods. Our results indicate that ice slurry ingestion following exercise does not impact TP-derived assessment of Tgint compared with Trec.

Rectal and Gastrointestinal Temperature Differ During Passive Heating and Subsequent Recovery

“…The quicker increase in T GI than T rec may be related to the protocol used to achieve hyperthermia. In contrast to the passive heating approach of the current study, the increase in T core in the abovementioned studies (Casa et al, 2007;Hosokawa et al, 2016;Deshayes et al, 2019;Gant et al 2006) was achieved by performing lower body exercise. It is conceivable that exercise increases T rec more quickly than passive heating, which may be linked to local heat production, convective and conductive exchanges, and the location of the measurement site (Taylor et al 2014).…”

“…Alternatively, it is possible that blood flow from the skin is distributed preferentially to the gastrointestinal rather than the rectal area, which would explain the lower responsiveness of T rec than T GI during both heating and recovery. A similar line of reasoning has been posited previouslydifferences between T rec and T GI may stem from differences in convective heat loss rates surrounding the intestine compared to the rectum, and/or from differing amounts of blood surrounding the relevant areas (Deshayes et al, 2019). As we did not assess local sweat rates or measures for blood flow distribution, follow-up studies may elucidate the discrepancy between T rec and T GI .…”

“…Literature investigating the bias between T rec and T GI is equivocal. Some report the same T rec as T GI (Casa et al, 2007;Hosokawa et al, 2016), some a higher (Deshayes et al, 2019) and some a lower T rec than T GI (Gant et al 2006). However, neither of these studies showed a differential response of T rec and T GI during heating (T rec < T GI ) and recovery (T rec > T GI ), which contrasts with the present findings, in which T GI appeared to be more sensitive to changes in exposure temperature, and T rec being slower to follow the general trend of the temperature change.…”

Effect of Glycerol-Induced Hyperhydration on a 5-kilometer Running Time-Trial Performance in the Heat in Recreationally Active Individuals

“…Heart rate was measured with a Garmin Premium heart rate monitor (Garmin, Olathe, KS, USA). Gastrointestinal temperature was measured using calibrated telemetric pills (CoreTemp, Palmetto, FL, USA) ingested 10 h prior to the participants’ arrival at the laboratory [ 19 ]. Skin temperature was measured with calibrated YSI 409 B probes (Yellow Springs Instrument, Yellow Springs, OH, USA) placed on the left side of the body on the chest, the forearm, the thigh and the calf.…”

Performance effects of internal pre- and per-cooling across different exercise and environmental conditions: A systematic review

“…The exclusion criteria determined a further removal of 69 articles. Two were review articles (24,25), three had a noncrossover design (26)(27)(28), nineteen reported only physiological, cognitive or perceptual performance measures (29)(30)(31)(32)(33)(34)(35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47), nine had no control or placebo group (48)(49)(50)(51)(52)(53)(54)(55)(56), five were conference abstracts/posters (57-61), three were performed in clinical context (62)(63)(64), twenty-seven did not report an exclusive effect of the internal cooling and one comprised underage participants (92). Forty-three articles fulfilled the eligibility criteria and data were extracted for qualitative analysis.…”