Comparison of metabolic substrates between exercise and cold exposure in skaters

Effects of Prolonged Cold Stress on Vascular Function in Guinea Pigs With Atherosclerosis

RESEARCH OBJECTIVE

This study explored the effects of long-term cold stress (CS) on aortic vascular function in guinea pigs.

RESEARCH METHODS

Hartley guinea pigs (n = 32) were divided into the following groups: atherosclerosis (AS), CS, and menthol-stimulated (M), and control (C). On days 1, 15, 30, 45, and 60, guinea pigs in the AS, CS, and M groups were intraperitoneally injected with bovine serum albumin. The C group was provided with maintenance feed and room temperature water. The AS group was provided with a high-fat diet and room temperature water. The CS group was maintained in a refrigerator at 4°C, while providing a high-fat diet and iced water. The M group was administered menthol solution, and provided with a high-fat diet and room temperature water. The modeling period lasted for 120 days. On day 121, abdominal aortic sera and aortic samples were obtained after intraperitoneal injection of sodium pentobarbital. Blood rheology tests were conducted to assess blood adhesion, biochemical tests to assess lipid levels, and enzyme-linked immunosorbent assays to detect serum nuclear factor-κB, tumor necrosis factor-α, and interleukin-1β, and endothelial nitric oxide synthase, nitric oxide, and endothelin-1 (ET-1) in aortic tissue. Hematoxylin and eosin and oil red O staining were used to examine pathologic changes in the aorta, Western blotting to detect transient receptor potential melastatin 8 and protein kinase G protein expression, quantitative polymerase chain reaction was used to measure VCAM-1 mRNA expression level.

RESEARCH FINDINGS

Prolonged exposure to CS exacerbated lipid-metabolism disorders in guinea pigs fed a high-fat diet, increased aortic vascular cell adhesion, and exacerbated vascular inflammation, leading to endothelial injury, ultimately worsening pathologic changes associated with aortic atherosclerosis.

Temperature-Related Variations in Physical Performance During Elite Soccer Matches

The aim of this study was to examine the differences in match running performance (MRP) according to the ambient temperature during UEFA Champions League (UCL) matches. Data were collected using an optical tracking system from all teams (n = 32) in all UCL matches (n = 125) during the 2022/23 season, and classified according to the ambient temperature at which matches were played: <5 °C, 6-10 °C, 11-20 °C, and >21 °C. The results revealed the following: (i) less total distance was covered in matches played at ≥21 °C compared to the matches played at 6-10 °C (d = 0.58), (ii) less high-speed running and high-intensity running were covered in matches played at ≥21 °C compared to the matches played at 11-20 °C (d = 0.54 and 0.43, respectively), 6-10 °C (d = 0.89 and 0.8, respectively), and ≤5 °C (d = 0.62 and 0.57, respectively), and (iii) less sprinting was covered in matches played at ≥21 °C compared to the matches played at 6-10 °C (d = 0.22). These findings indicated the significant differences in MRP when UCL matches were played at different ambient temperatures, with notable reductions in overall and high-intensity efforts in warmer conditions.

Effects of environmental temperature on physiological responses during submaximal and maximal exercises in soccer players

Background

Although thermoregulation is effective in regulating body temperature under normal conditions, exercise or physical activity in extreme cold or heat exerts heavy stress on the mechanisms that regulate body temperature. The purpose of this study was to investigate the effects of environmental temperature on physiological responses and endurance exercise capacity during submaximal and maximal exercises in healthy adults.

Methods

Nine male soccer players participated in this study. In this study, three environmental temperatures were set at 10 ± 1°C, 22 ± 1°C, and 35 ± 1°C with the same humidity (60 ± 10%). The participants cycled for 20 minutes at 60% maximum oxygen uptake (60% VO₂max), and then exercise intensity was increased at a rate of 0.5 kp/2 min until exhaustion at three different environmental conditions.

Results

Oxygen uptake and heart rate were lower in a moderate environment (22 ± 1°C) than in a cool (10 ± 1°C) or hot (35 ± 1°C) environment at rest and during submaximal exercise, and were higher during maximal exercise (p < 0.05). Minute ventilation was lower at 22 ± 1°C than at 10 ± 1°C or 35 ± 1°C at rest and during submaximal exercise, and no significant differences were observed in minute ventilation during maximal exercise (p < 0.05). Blood lactate concentrations were lower at 22 ± 1 °C than at 10 ± 1°C or 35 ± 1°C at rest and during submaximal exercise, and were higher during maximal exercise (p < 0.05). Time to exhaustion during exercise was longer at 22 ± 1°C than at 10 ± 1°C or 35 ± 1°C (p < 0.05).

Conclusion

It is concluded that physiological responses and endurance exercise capacity are impaired under cool or hot conditions compared with moderate conditions, suggesting that environmental temperature conditions play an important role for exercise performance.

Mitochondrial dysfunction in aging rat brain regions upon chlorpyrifos toxicity and cold stress: an interactive study

Mitochondrial dysfunction and consequent energy depletion are the major causes of oxidative stress resulting to bring alterations in the ionic homeostasis causing loss of cellular integrity. Our previous studies have shown the age-associated interactive effects in rat central nervous system (CNS) upon co-exposure to chlorpyrifos (CPF) and cold stress leading to macromolecular oxidative damage. The present study elucidates a possible mechanism by which CPF and cold stress interaction cause(s) mitochondrial dysfunction in an age-related manner. In this study, the activity levels of Krebs cycle enzymes and electron transport chain (ETC) protein complexes were assessed in the isolated fraction of mitochondria. CPF and cold stress (15 and 20 °C) exposure either individually or in combination decreased the activity level of Krebs cycle enzymes and ETC protein complexes in discrete regions of rat CNS. The findings confirm that cold stress produces significant synergistic effect in CPF intoxicated aging rats. The synergism between CPF and cold stress at 15 °C caused a higher depletion of respiratory enzymes in comparison with CPF and cold stress alone and together at 20 °C indicating the extent of deleterious functional alterations in discrete regions of brain and spinal cord (SC) which may result in neurodegeneration and loss in neuronal metabolic control. Hence, co-exposure of CPF and cold stress is more dangerous than exposure of either alone. Among the discrete regions studied, the cerebellum and medulla oblongata appears to be the most susceptible regions when compared to cortex and SC. Furthermore, the study reveals a gradual decrease in sensitivity to CPF toxicity as the rat matures.

Brown adipose tissue in the treatment of obesity and diabetes: Are we hot enough?

The identification of functional brown adipose tissue in human adults has intensified interest in exploiting thermogenic energy expenditure for the purpose of weight management. However, food intake and energy expenditure are tightly regulated and it is generally accepted that variation in one component results in compensatory changes in the other. In the context of weight loss, additional biological adaptations occur in an attempt to further limit weight loss. In the present review, we discuss the relationship between increasing energy expenditure and body weight in humans, including the effects of cold exposure. The data raise the possibility that some processes, particularly those involved in thermogenesis, induce less compensatory food intake for a given magnitude of additional energy expenditure, a state we term the ‘thermogenic disconnect’. Although cold exposure increases thermogenesis and can putatively be exploited to induce weight loss, there are multiple adaptive responses to cold, of which many actually reduce energy expenditure. In order to optimally exploit either cold itself or agents that mimic cold for thermogenic energy expenditure, these non‐thermogenic cold responses must be considered. Finally, the relative contribution of brown adipose tissue vs other thermogenic processes in humans remains to be defined. However, overall the data suggest that activation of cold‐induced thermogenic processes are promising targets for interventions to treat obesity and its secondary metabolic complications. (J Diabetes Invest, doi:10.1111/j.2040‐1124.2011.00158.x, 2011)

Skiing and intermittant claudication: an aberrant presentation

Lower extremity peripheral arterial disease frequently presents with intermittent claudication, typically manifest in lower extremity pain or cramping associated with exercise, generally walking. Occasionally early onset of disease can be associated with running. This report describes the unusual presentation of leg pain associated with skiing and relieved by cessation of skiing immediately caused by focal iliac artery stenosis.