Impaired glucose tolerance after brief heat exposure: a randomized crossover study in healthy young men.

A high demand on thermoregulatory processes may challenge homoeostasis, particularly regarding glucose regulation. This has been understudied, although it might concern millions of humans. The objective of this project was to examine the isolated and combined effects of experimental short-term mild heat exposure and metabolic level on glucoregulation. Two experimental randomized crossover studies were conducted. Ten healthy young men participated in study A, which comprises four sessions in a fasting state at two metabolic levels [rest and exercise at 60% of maximal oxygen uptake (O2) for 40 min] in two environmental temperatures (warm: 31°C and control: 22°C). Each session ended with an ad libitum meal, resulting in similar energy intake across sessions. In study B, 12 healthy young men underwent two 3 h oral glucose tolerance tests (OGTTs) in warm and control environmental temperatures. Venous blood was sampled at several time points. In study A, repeated measure ANOVAs revealed higher postprandial serum glucose and insulin levels with heat exposure. Glycaemia following the OGTT was higher in the warm temperature compared with control. The kinetics of the serum glucose response to the glucose load was also affected by the environmental temperature (temperature-by-time interaction, P=0.030), with differences between the warm and control conditions observed up to 90 min after the glucose load (all P<0.033). These studies provide evidence that heat exposure alters short-term glucoregulation. The implication of this environmental factor in the physiopathology of Type 2 diabetes has yet to be investigated.

Ambient temperature-related exaggerated post-prandial insulin response in a young athlete: a case report and implications for climate change.

The objective is to present the case of a 21-yr-old athlete observed with non-physiological immediate postprandial insulin response (1162 pmol/l; normal glucose excursion: 6.6 mmol/l), in a warm environment. No suspicion or evidence of any underlying pathology was found in this well-trained Afro-Caribbean male runner. He never reported any hypoglycemic episode. When performing the same protocol performed in a cooler environment (21.0°C vs 30.3°C), only physiological responses were observed. We conclude that 1) youth, leanness and regular exercise training are not absolutely protective against glucose metabolism impairment in apparently healthy subjects; 2) ambient temperature should be regarded as a potential source of glucose metabolism impairment.

Effect of heat exposure and exercise on food intake regulation: A randomized crossover study in young healthy men.

OBJECTIVE: The effect of physical activity on food intake regulation may be moderated by environmental temperature. The aim of the study was to determine the single and combined effects of metabolic activity and temperature on energy intake and its hormonal regulation. METHODS: A randomized crossover study was conducted in the laboratory. Ten healthy and physically active young Afro-Caribbean men participated in four experimental sessions (rest at 22°C and 31°C and cycling at 60% of their maximal oxygen uptake at 22°C and 31°C, all for 40 min). Each test period was followed by a 30-min recovery period and then an ad libitum meal. The main outcome measures were energy balance, subjective appetite, and plasma pancreatic polypeptide (PP), cholecystokinin (CCK) and ghrelin concentrations. RESULTS: Relative energy intake was significantly decreased whereas plasma PP was increased in the exercise conditions (p=0.004 and p=0.002, respectively). Postprandial levels of CCK were elevated only in the rest conditions. Exposure to heat induced a decrease in plasma ghrelin (p=0.031). CONCLUSIONS: Exercise induced a short-term energy deficit. However, modifications in the hormonal regulation of food intake in response to short-term heat or heat and exercise exposure seem to be minor and did not induce changes in energy intake. This trial was registered at clinicaltrials.gov as NCT02157233.

Compartment syndrome of the thigh after blunt trauma: a complication not to be ignored.

We report a case of anterior thigh compartment syndrome, which occurred after man's thigh was bruised after flipping repeatedly over his bike and being hit by the frame of the bike nearly at around 6 pm. The next day at 1:30 am, he was admitted to the hospital. The initial presentation was a hematoma, and the patient was kept in bed with local cooling. The compartment syndrome of the thigh (CST) diagnosis was made around 6:00 pm when the level of pain was interpreted as disproportionate to the treated lesion; anterior compartment pressure measure was 84 mmHg. A compartment fasciotomy was performed. It is difficult to diagnose a CST in case of muscular contusion as the latter causes symptoms that are similar to CST. A conservative treatment without fasciotomy was carried out by several authors, especially in sportsmen showing a CST following contusion. This conservative treatment implies close monitoring of intramuscular pressures and adjuvant measures (bed rest, holding the thigh at the heart level and oxygenotherapy).