Temperatures measured by a deep body thermometer (Coretemp®) compared with tissue temperatures measured at various depths using needles placed into the sole of the foot

The use of a cold pack during resistance exercises is effective for reducing intramuscular oxygenation and increasing myoelectric activity

[Purpose] The purpose of this study was to determine the efficacy of using a cold pack while doing resistance exercises for enhancing muscle strength and muscle hypertrophy through decreased intramuscular oxygenation and/or increased myoelectric activity. [Participants and Methods] Twenty-four resistance-trained males (age: 26.4 ± 8.4 years, height: 169.3 ± 5.2 cm, body weight: 74.7 ± 8.8 kg) involved in this study. All the participants completed two experimental sessions in random order (cold pack resistance exercise and resistance exercise) with a 3-day interval. Four types of resistance exercises (4 sets × 8 repetitions with an 8-repetition maximum) targeting the right triceps brachii muscle were performed in both the experimental sessions. [Results] The percentage baseline oxyhemoglobin/myoglobin level during resistance exercise was significantly lower, the half-recovery time of muscle oxygenation in intervals between sets was significantly longer, and the myoelectric activity was significantly higher in the cold pack resistance exercise than in the resistance exercise session. [Conclusion] The results suggest that using a cold pack with resistance exercises is effective in inducing intramuscular deoxygenation and increasing myoelectric activity and may be useful for increasing muscle strength and inducing hypertrophy.

A Combined Hot and Hypoxic Environment during Maximal Cycling Sprints Reduced Muscle Oxygen Saturation: A Pilot Study

The present study investigated the effects of a combined hot and hypoxic environment on muscle oxygenation during repeated 15-s maximal cycling sprints. In a single-blind, cross-over study, nine trained sprinters performed three 15-s maximal cycling sprints interspersed with 7-min passive recovery in normoxic (NOR; 23℃, 50%, FiO₂ 20.9%), normobaric hypoxic (HYP; 23℃, FiO₂ 14.5%), and hot normobaric hypoxic (HH; 35℃, FiO₂ 14.5%) environments. Relative humidity was set to 50% in all trials. The vastus lateralis muscle oxygenation was evaluated during exercise using near-infrared spectroscopy. The oxygen uptake (VO₂) and arterial oxygen saturation (SpO₂) were also monitored. There was no significant difference in peak or mean power output among the three conditions. The reduction in tissue saturation index was significantly greater in the HH (-17.0 ± 2.7%) than in the HYP (-10.4 ± 2.8%) condition during the second sprint (p < 0.05). The average VO₂ and SpO₂ were significantly lower in the HYP (VO₂ = 980 ± 52 mL/min, SpO₂ = 82.9 ± 0.8%) and HH (VO₂ = 965 ± 42 mL/min, SpO₂ = 83.2 ± 1.2%) than in the NOR (VO₂ = 1149 ± 40 mL/min, SpO₂ = 90.6 ± 1.4%; p < 0.05) condition. In conclusion, muscle oxygen saturation was reduced to a greater extent in the HH than in the HYP condition during the second bout of three 15-s maximal cycling sprints, despite the equivalent hypoxic stress between HH and HYP.

Differences in the Repeated Sprint Performance Between the First and Latter Halves of Trials Under Conditions of Several Thermal States in Exercising Muscles

ABSTRACT

Inoue, K, Yamashita, N, Kume, M, and Yoshida, T. Differences in the repeated sprint performance between the first and latter halves of trials under conditions of several thermal states in exercising muscles. J Strength Cond Res 35(3): 782-790, 2021-The purpose of this study was to determine whether the effects of thermal states in exercising muscle on repeated sprint cycling (RSC) performance differ between the first and latter half of trials. Nine male subjects performed 8 × 8 seconds of RSC with a 40-second rest period. The subjects wore water-perfused trousers with water at 6° C (COLD), 17° C (COOL), 30° C (WARM), or 44° C (HOT). During the first half of trials, the peak power output (PPO), mean power output (MPO), and sum of work output (SWO) were significantly (p < 0.05) greater under the WARM and HOT conditions than under the COLD and COOL conditions, and a difference in the PPO and MPO between WARM and HOT was noted in the second sprint bout during the first half of the exercise. However, during the latter half of trials, there was no significant difference in the PPO, MPO, and SWO among the 4 conditions. The tympanic temperature (Tty) was significantly elevated under the HOT condition but fell under the COLD and COOL conditions, whereas the Tty under the WARM condition did not change significantly (p < 0.05) during the experiment. The total sweat loss was significantly (p < 0.05) greater in the HOT condition than in the other conditions. These results suggest that the effect of thermal states in exercising muscle on the RSC performance is greater in the first half of exercise than in the latter half, possibly because of the elevation of the core temperature and sweat loss under HOT conditions.

Changes in the physiological strain and graded exercise performance due to warming or cooling of the lower body in a temperate environment

BACKGROUND

The effects of a reduced or mildly elevated exercising muscle temperature on the graded exercise test (GXT) performance have yet to be studied. The present study clarified the effects of a range of exercising muscle temperatures on GXT performance in a temperate environment.

METHODS

Eight male subjects (age: 24.0±0.5 years old; height: 175±2 cm; weight: 64.8±2.0 kg; peak oxygen consumption [V̇O<inf>2peak</inf>]: 51.1±2.4 mL/kg/min) performed 4 GXTs at different exercising muscle temperatures using a cycle-ergometer in a temperate environment (24.1±0.2 °C). The exercise began at 0.3 kilopond (kp) with 60 revolutions per minute (rpm) and increased 0.3 kp every minute until volitional exhaustion. Subjects passively cooled (averaged deep thigh and calf temperature [Tmm], cold: 31 °C or cool: 33 °C) or warmed (Tmm; warm: 35 °C or hot: 37 °C) the exercising muscle using water perfusion pants throughout the test. The peak oxygen consumption (V̇O<inf>2peak</inf>), exercise time to exhaustion (TTE), heart rate (HR), tympanic (Tty) and mean body temperature (Tb), and total sweat loss were also measured.

RESULTS

No significant differences were observed in the V̇O<inf>2peak</inf> or TTE among the 4 conditions; however, the HR, Tb, and total sweat loss were significantly higher (P<0.05) under warming conditions than cooling conditions.

CONCLUSIONS

These results suggest that although the cardiovascular and thermoregulatory strain is higher under warming conditions than cooling conditions, the exercising muscle temperature does not affect the performance of a GXT lasting approximately 15 min in a temperate environment.

Identifying Critical Design Parameters for Improved Body Temperature Measurements: A Clinical Study Comparing Transient and Predicted Temperature Measurements

Readily available store brand, or “home,” thermometers are used countless times in the home and clinic as a first diagnostic measure of body temperature. Measurement inaccuracies may lead to unnecessary medical visits or medication (false positives), or, potentially worse, lack of intervention when a person is truly sick (false negatives). A critical first step in the design process is to determine the shortcomings of the existing designs. For this project, we evaluated the accuracy of three currently available store brand thermometers in a pediatric population. The accuracies of the thermometers were assessed by comparing their body temperature predictions to those measured by a specially designed and calibrated and fast-responding reference thermometer. The reference thermometer was placed at the measurement site simultaneously with the store brand thermometer and recorded the temperature at the measurement site continuously. More than 300 healthy or sick pediatric subjects were enrolled in this study. Temperatures were measured at both the oral and axillary (under the arm) sites. The store brand thermometer measurements characteristically deviated from the reference thermometer temperature after 120 s, and the deviations did not follow a consistent pattern. The Brand C thermometers had the greatest deviations of up to 3.7 °F (2.1 °C), while the Brand A thermometers had the lowest deviations; however, they still deviated by up to 1.9 °F (1.1 °C). The data showed that the tested store brand thermometers had lower accuracy than the ±0.2 °F (0.1 °C) indicated in their Instructions for Use. Our recorded reference (transient) data showed that there was a wide variation in the transient temperature profiles. The store brand thermometers tested stated in their documentation that they are able to predict a body temperature based on transient temperature values over the first 5–10 s of measurements, implying that they use an embedded algorithm to extrapolate to the steady-state temperature. Significant deviations from the maximum temperature after time t = 4.6t0.63 illustrated that the transient temperature profiles may not be represented by an exponential function with a single time constant, t0.63. The accuracy of those embedded algorithms was not confirmed by our study, since the predicted body temperatures do not capture the large variations observed over the initial 10 s of the measurements. A thermometer with an error of several degrees Fahrenheit may result in a false positive or negative diagnosis of fever in children. The transient temperature measurements from our clinical study represent unique and critical data for helping to design the next generation of readily available, highly accurate, home thermometers.

The influence of internal and skin temperatures on active cutaneous vasodilation under different levels of exercise and ambient temperatures in humans

To clarify the influence of internal and skin temperature on the active cutaneous vasodilation during exercise, the body temperature thresholds for the onset of active vasodilation during light or moderate exercise under different ambient temperature conditions were compared. Seven male subjects performed 30 min of a cycling exercise at 20 % or 50 % of peak oxygen uptake in a room maintained at 20, 24, or 28 °C. Esophageal (Tes) and mean skin temperature (Tsk) as measured by a thermocouple, deep thigh temperature (Tdt) by the zero-heat-flow (ZHF) method, and forearm skin blood flow by laser-Doppler flowmetry (LDF) were monitored. The mean arterial pressure (MAP) was also monitored non-invasively, and the cutaneous vascular conductance (CVC) was calculated as the LDF/MAP. Throughout the experiment, the Tsk at ambient temperatures of 20, 24, and 28 °C were approximately 30, 32, and 34 °C, respectively, for both 20 % and 50 % exercise. During 50 % exercise, the Tes or Tdt thresholds for the onset of the increase in CVC were observed to be similar among the 20, 24, and 28 °C ambient conditions. During 20 % exercise, the increase in Tes and Tdt was significantly lower than those found at 50 %, and the onset of the increase in CVC was only observed at 28 °C. These results suggest that the onset of active vasodilation was affected more strongly by the internal or exercising tissue temperatures than by the skin temperatures during exercise performed at a moderate load in comparison to a light load under Tsk variations ranging from 30 °C to 34 °C. Therefore, the modification by skin temperature of the central control on cutaneous vasomotor tone during exercise may differ between different exercise loads.

Relationship between mean body temperature calculated by two- or three-compartment models and active cutaneous vasodilation in humans: a comparison between cool and warm environments during leg exercise

The aim of this study was to assess whether the three-compartment model of mean body temperature (Tb3) calculated from the esophageal temperature (Tes), temperature in deep tissue of exercising muscle (Tdt), and mean skin temperature (Tsk) has the potential to provide a better match with the thermoregulatory responses than the two-component model of mean body temperature (Tb2) calculated from Tes and Tsk. Seven male subjects performed 40 min of a prolonged cycling exercise at 30% maximal oxygen uptake at 21°C or 31°C (50% relative humidity). Throughout the experiment, Tsk, Tb2, Tb3, and Tdt were significantly (P < 0.01) lower at 21°C than at 31°C temperature conditions, while Tes was similar under both conditions. During exercise, an increase in cutaneous vascular conductance (skin blood flow / mean arterial pressure) over the chest (%CVCc) was observed at both 21°C and 31°C, while no increase was observed at the forearm at 21°C. Furthermore, the Tb3 and Tdt threshold for the onset of the increase in %CVCc was similar, but the Tes and Tb2 threshold differed significantly (P < 0.05) between the conditions tested. These results suggest that active cutaneous vasodilation at the chest is related more closely to Tb3 or Tdt than that measured by Tes or Tb2 calculated by Tes and Tsk during exercise at both 21°C and 31°C.

A real time non-invasive monitoring system for detection of hypovolemic state using RR interval variability in very low frequency ranges

In offline analysis, very low frequency variability in RR interval and systolic arterial pressure has been reported below 0.1 Hz during head-up tilt (HUT) tests in conditions similar to hypovolemic states in humans. We designed a real time and non-invasive monitoring system of very low frequency RR interval variability to detect the hypovolemic state resulting from internal and external hemorrhages. Eight male Sprague-Dawley rats were subjected to monitoring before (normal state) and after withdrawal of 2 ml blood/100 g body weight over 15 minutes (hypovolemic state). Using one-channel electrocardiogram (ECG), the detection system monitored in real time the very low frequency components of RR interval variability using Fast Fourier Transform (FFT). Temperature mappings of rat abdomen were conducted simultaneously to monitor the hypothermic state after blood withdrawal using a local temperature mapping system with a deep body thermometer. This system demonstrated oscillation of the RR interval at 0.075 +/- 0.015 Hz in real time after blood withdrawal. The deep body temperature decreased significantly from 37.4 +/- 0.9 degrees centigrade to 35.5 +/- 1.2 degrees centigrade (p < 0.05) within 1 hour after blood withdrawal. Our monitoring system appears promising for the detection of hypovolemic state resulting from massive hemorrhage using a one-channel ECG monitor.

Non-contact determination of vital sign alterations in hypovolaemic states induced by massive haemorrhage: an experimental attempt to monitor the condition of injured persons behind barriers or under disaster rubble

To assess a non-contact method to determine the physical alteration of human subjects confined behind a barrier or under disaster rubble, an experimental, non-contact monitoring system was tested on rabbits in a hypovolaemic state. New Zealand male rabbits behind a barrier were subjected to hypovolaemic shock induced by the withdrawal of arterial blood (2ml per 100g body weight). The hypovolaemic state was determined by linear discriminant analysis using non-contact-derived variables: heart rate X1 and respiratory rate X2. Sixteen rabbits were equally divided between the hypovolaemic and control groups. To obtain the heart and respiratory rates simultaneously, the fast Fourier transform (FFT) was performed on the 1215MHz microwave radar analogue output. The linear discriminant function calculated by non-contact-derived variables was negative in the eight hypovolaemic rabbits and positive in the eight controls, so that the linear discriminant function could distinguish the hypovolaemic group from the control group. The Mahalanobis D-square (an index for classification accuracy) was 5908; the classification error rate corresponding to this value was small and negligible. The hypovolaemic rabbits developed metabolic acidosis (HCO3- 18.6+/-11.1 mmol l(-1) and pH 7.15+/-0.18 in arterial blood). The systolic blood pressure of the hypovolaemic group and the control was 56+/-4 and 83+/-6 mmHg, respectively (p < 0.01). The proposed method appears promising for applications to monitor the condition of human subjects behind barriers or under disaster rubble.

A new method to detect systemic inflammatory response syndrome by continuous monitoring system: an experimental study in rats

A continuous monitoring system was designed for detection of systemic inflammatory response syndrome (SIRS) using spectrum analyser and local temperature mapping system with deep body thermometer. This method demonstrated significant increases of heart and respiratory rates and deep body temperature from normal levels within 120 minutes after lipopolysaccharide administration in rats. Our monitoring system appears promising for clinical detection of SIRS in the early stages to prevent multiple organ failure.

Effectiveness of acupuncture and moxibustion treatment for lymphedema following intrapelvic lymph node dissection: a preliminary report

Although it is difficult in Western medicine to eliminate edema occurring in the lower extremities after intrapelvic lymph node dissection for malignant gynecologic tumors, we successfully treated or prevented this postoperative complication with moxibustion and acupuncture, initiated after the occurrence of lymphedema in 12 patients and as soon as possible after surgery in 12 others. An increase in deep body temperature with acupuncture or moxibustion was found to be essential for successful treatment.

"Deep-forehead" temperature correlates well with blood temperature

PURPOSE

To evaluate the accuracy and precision of "deep-forehead" temperature with rectal, esophageal, and tympanic membrane temperatures, compared with blood temperature.

METHODS

We studied 41 ASA physical status 1 or 2 patients undergoing abdominal and thoracic surgery scheduled to require at least three hours. "Deep-forehead" temperature was measured using a Coretemp thermometer (Terumo, Tokyo, Japan). Blood temperature was measured with a thermistor of a pulmonary artery. Rectal, tympanic membrane, and distal esophageal temperatures were measured with thermocouples. All temperatures were recorded at 20 min intervals after the induction of anesthesia. We considered blood temperature as the reference value. Temperatures at the other four sites were compared with blood temperature using correlation, regression, and Bland and Altman analyses. We determined accuracy (mean difference between reference and test temperatures) and precision (standard deviation of the difference) of 0.5 degrees C to be clinically acceptable.

RESULTS

"Deep-forehead" temperature correlated well with blood temperature as well as other temperatures, the determination coefficients (r2) being 0.85 in each case. The bias for the "deep-forehead" temperature was 0.0 degrees C, which was the same as tympanic membrane temperature and was smaller than rectal and esophageal temperatures. The standard deviation of the differences for the "deep-forehead" temperature was 0.3 degrees C, which was the same as rectal temperature.

CONCLUSIONS

We have demonstrated that the "deep-forehead" temperature has excellent accuracy and clinically sufficient precision as well as other three core temperatures, compared with blood temperature.