Sigurbjorn Arngrimsson | University of Iceland (original) (raw)
Papers by Sigurbjorn Arngrimsson
European Geriatric Medicine, 2013
ABSTRACT Background Regular physical activity (PA) and nutritional counseling can reduce weight a... more ABSTRACT Background Regular physical activity (PA) and nutritional counseling can reduce weight and trunk fat accumulation and influence cardiometabolic factors. Methods This study was an exercise training and nutritional counseling intervention, conducted in two 6-month phases. Participants were assessed at baseline and at 6 and 12 months. Participants (54 males and 63 females aged 71–90) were randomized into immediate exercise training group (Group 1) and delayed exercise training group (Group 2). At time-point 2, the groups crossed over. Results After the exercise training-phase by Group 1, a statistically significant increase (P < 0.05) was seen in physical activity (PA), energy intake, and total lean mass. A significant decrease was seen in weight, total fat mass, trunk fat mass, waist circumference, and blood pressure. At the 6-month follow-up, Group 1 saw a significant decrease in PA, energy intake, total lean mass and blood pressure. A significant increase was seen in waist circumference and total fat mass. After the 6-month control phase by Group 2, a significant decrease was measured in PA, systolic blood pressure, total fat mass, fat mass of the trunk and waist circumference. After a delayed 6-month exercise training-phase by Group 2, a significant increase was measured in PA, and a decrease in weight, total fat mass, trunk fat mass, waist circumference, blood pressure and triglyceride. Conclusion Our findings suggest that positive improvements in body composition and cardiometabolic factors in old people may be achieved by systematic exercise training in combination with nutrition counseling. This should be considered as an integral part of the health care system.
PLOS ONE, 2015
The interaction between fatness, fitness, and C-reactive protein (CRP) in adolescents is not well... more The interaction between fatness, fitness, and C-reactive protein (CRP) in adolescents is not well characterized but may be important to prevent low grade inflammation. The purpose of this study was to assess the relationship between adiposity, different expressions of fitness, and CRP in late adolescence using direct measures of fitness and fatness. Anthropometric measurements were taken on 245 eighteen-year-old participants (116 girls). Fasting CRP, glucose, and insulin were measured and homeostatic model assessment (HOMA) calculated. Body composition was estimated via dual energy X-ray absorptiometry. Fitness was assessed with maximal oxygen uptake (VO2max) during a treadmill test and also expressed relative to the fat-free mass (VO2maxFFM). Prevalence of overweight/obesity based on body mass index (BMI) was 20.7% and 25.6% among girls and boys, respectively (p = 0.407), but 42.5% and 58.1% when based on body fat percentage (%fat, p = 0.015). Higher proportion of boys (81.3%) than girls (54.5%) were highly fit (p&amp;amp;amp;amp;amp;amp;amp;lt;0.001), but the percentage of girls with high levels of CRP was greater (12.1% vs 6.2%, p = 0.028). Adiposity, indicated with BMI, waist circumference, fat mass, android fat mass (aFM), or %fat, was positively associated with CRP independent of VO2max (r = 0.13-0.18, p&amp;amp;amp;amp;amp;amp;amp;lt;0.05) and VO2maxFFM (r = 0.24-0.32, p&amp;amp;amp;amp;amp;amp;amp;lt;0.001). VO2max, was negatively associated with CRP independent only of BMI and waist circumference (r = -0.21, p = 0.001), but not %fat, fat mass or aFM (r = -0.08 to -0.12, p&amp;amp;amp;amp;amp;amp;amp;gt;0.05). VO2maxFFM was unrelated to CRP with (r = -0.07 to -0.11, p&amp;amp;amp;amp;amp;amp;amp;gt;0.05) or without (r = -0.10, p = 0.142) adjustment for adiposity. Additional adjustment for HOMA did not change any of the relationships, although the coefficients were attenuated. Fatness has a greater association with CRP than fitness in late adolescence. However, VO2maxFFM, which is truly independent of adiposity, is unrelated to CRP, indicating that the effects of fitness might be mediated via the fatness component embedded in fitness expressed relative to body mass.
Medicine and Science in Sports and Exercise, 2008
Pediatric exercise science, 2008
The purpose of this study was to validate an equation that has been used to predict peak oxygen u... more The purpose of this study was to validate an equation that has been used to predict peak oxygen uptake (VO2peak) and, if invalid, to develop a new equation predicting VO2peak from performance on a cycle ergometer test. Forty-five 9- and 15-year-old children underwent a VO2peak test and were randomized into developmental (DEV) and cross-validation (C-V) groups. The equation under validation, which requires knowledge of resting energy expenditure (REE), underestimated VO2peak (p < .05), but once adjusted with a new parameter calculated in DEV, it cross-validated well (rYY' = .98, SE = .18 L . min-1). The accuracy of a new prediction equation built in DEV, not using REE, was confirmed in C-V (rYY' = .98, SE = .17 L . min-1) and the slope and intercept were not different from the line of identity (p < .05). VO2peak in schoolchildren can be predicted with good accuracy from an equation based on the whole sample [VO2peak = -1.5986 + 0.0115 . (maximal power output) + 0.0109 ....
International journal of obesity (2005), 2006
To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 19... more To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 1988 and 1994 in a population of high birth weight. Icelandic cohorts born in 1988 and 1994. Out of 1328, 9- and 15-year-old children from 18 randomly selected schools all over Iceland, 934 participated (71%). Height and mass were measured by the investigators. Also, height and mass at birth, and at age 2.5, 6, 9, and 12 years, were collected from maternity wards and school health registers. The prevalence of overweight children ranged from 10.1% for 2.5-year-olds to 18.7% for 9-year-olds. No difference was observed between the two cohorts or sex. The prevalence of obesity in the 1994 cohort (4.3%) was significantly higher (P = 0.01) at age 6 years, compared to the 1988 cohort (1.1%). The children who were overweight at age 2.5 years were more likely to be overweight at age 6 (OR=12.2) and 9 years (OR=4.9), but not significantly at age 12 or 15 years, compared with normal weight 2.5-year-o...
Journal of applied physiology (Bethesda, Md. : 1985), 2003
The purpose of this study was to examine the effect of resistance exercise on postprandial lipemi... more The purpose of this study was to examine the effect of resistance exercise on postprandial lipemia. Fourteen young men and women participated in each of three treatments: 1) control (Con), 2) resistance exercise (RE), and 3) aerobic exercise (AE) estimated to have an energy expenditure (EE) equal that for RE. Each trial consisted of performing a treatment on day 1 and ingesting a fat-tolerance test meal 16 h later (day 2). Resting metabolic rate and fat oxidation were measured at baseline and at 3 and 6 h postprandial on day 2. Blood was collected at baseline and at 0.5, 1, 2, 3, 4, 5, and 6 h after meal ingestion. RE and AE were similar in EE [1.7 +/- 0.1 vs. 1.6 +/- 0.1 (SE) MJ, respectively], as measured by using the Cosmed K4b(2). Baseline triglycerides (TG) were significantly lower after RE than after Con (19%) and AE (21%). Furthermore, the area under the postprandial response curve for TG, adjusted for baseline differences, was significantly lower after RE than after Con (14%...
Journal of applied physiology (Bethesda, Md. : 1985), 2003
We tested the hypothesis that elevation in heart rate (HR) during submaximal exercise in the heat... more We tested the hypothesis that elevation in heart rate (HR) during submaximal exercise in the heat is related, in part, to increased percentage of maximal O(2) uptake (%Vo(2 max)) utilized due to reduced maximal O(2) uptake (Vo(2 max)) measured after exercise under the same thermal conditions. Peak O(2) uptake (Vo(2 peak)), O(2) uptake, and HR during submaximal exercise were measured in 22 male and female runners under four environmental conditions designed to manipulate HR during submaximal exercise and Vo(2 peak). The conditions involved walking for 20 min at approximately 33% of control Vo(2 max) in 25, 35, 40, and 45 degrees C followed immediately by measurement of Vo(2 peak) in the same thermal environment. Vo(2 peak) decreased progressively (3.77 +/- 0.19, 3.61 +/- 0.18, 3.44 +/- 0.17, and 3.13 +/- 0.16 l/min) and HR at the end of the submaximal exercise increased progressively (107 +/- 2, 112 +/- 2, 120 +/- 2, and 137 +/- 2 beats/min) with increasing ambient temperature (T(a))...
American journal of human biology : the official journal of the Human Biology Council, 2000
This study used estimates of body composition from a four-component model (%Fat(d,w,m)) to determ... more This study used estimates of body composition from a four-component model (%Fat(d,w,m)) to determine whether the assumed density (D(ffm)) and the composition of the fat-free mass (FFM), and estimates of body composition from methods based on two- and three-component models are valid in distance runners. Measures of body density (D(b)) by underwater weighing, total body water by deuterium dilution, and bone mineral by dual-energy X-ray absorptiometry (DXA) were obtained in 10 female and 12 male runners and an equal number of controls matched for age, height, weight, gender, and ethnicity. D(ffm) of the runners did not differ from 1.1 g.cm(-3) or from the controls even though the composition of the FFM differed from that assumed. Therefore, percentage of body fat (%Fat) from densitometry did not differ from %Fat(d,w,m) in the runners, although individual variation was substantial (-5.3 to 3.0% body mass, SD(diff) = 2.1% body mass). Three-component model estimates of %Fat from D(b) and...
International journal of sport nutrition and exercise metabolism, 2009
This experiment examined the effect of a moderate dose of caffeine on quadriceps muscle pain duri... more This experiment examined the effect of a moderate dose of caffeine on quadriceps muscle pain during a bout of high-intensity cycling in low- versus high-caffeine-consuming males. College-age men who were low (< or =100 mg/day; n = 12) or high (> or =400 mg/day; n = 13) habitual caffeine consumers ingested caffeine (5 mg/kg body weight) or a placebo in a counterbalanced order and 1 hr later completed 30 min of cycle ergometry at 75-77% of peak oxygen consumption. Perceptions of quadriceps muscle pain, as well as oxygen consumption, heart rate, and work rate, were recorded during both bouts of exercise. Caffeine ingestion resulted in a statistically significant and moderate reduction in quadriceps muscle-pain-intensity ratings during the 30-min bout of high-intensity cycle ergometry compared with placebo ingestion in both low (d = -0.42) and high (d = -0.55) caffeine consumers. The results suggest that caffeine ingestion is associated with a moderate hypoalgesic effect during hi...
Læknablađiđ, 2012
The purpose of the study was to examine metabolic risk factors among 18 year old high-school stud... more The purpose of the study was to examine metabolic risk factors among 18 year old high-school students and compare students attending vocational and traditional schools. Participants (147 boys and 130 girls) were randomly selected. Physical activity (PA) was measured with pedometers and aerobic fitness (fitness) with maximal oxygen uptake test on a treadmill. Height, weight, waist circumference (WC), and body mass index (BMI) were measured and percentage body fat (%Fat) assessed with dual energy X-ray absorptiometry. Resting blood pressure (BP) and serum lipids and glucose were measured. According to BMI, 23% of the students were overweight/obese, 20% had elevated WC, and 51% increased %Fat. In addition, 11% of the students had high-density lipoprotein below recommended levels, and 8% had low-density lipoprotein and 9% triglycerides above advised values. Finally, 10% had borderline or high systolic BP. In contrast, 84% of the students had fair or higher levels of fitness, although on...
Læknablađiđ, 2013
Good functional performance in elderly people greatly improves their changes of independence and ... more Good functional performance in elderly people greatly improves their changes of independence and well-being. Conversely, bad functional performance can impair their capability of managing the activities of daily life.. The main goal of this study was to investigate the effects of a 6-months' multimodal training intervention on the physical performance of males and females, possible gender differences and the outcome 6 and 12 months after its completion. This study examined 71-90 year old healthy seniors (n=117) participating in the AGES Reykjavik Study. It was a randomized and controlled cross-over trial, conducted in three 6-months' phases (time-points). After enrollment and baseline assessments, the study group was divided in two. Group 1 received 6-months' training while group 2 served as a control. In the second 6 months' phase, group 1 received no formal training while group 2 did. In the third phase, neither group received training. The groups' physical con...
To compare the effect of hyperthermia on maximal oxygen uptake ( _ V O 2max ) in men and women, _... more To compare the effect of hyperthermia on maximal oxygen uptake ( _ V O 2max ) in men and women, _ V O 2max was measured in 11 male and 11 female runners under seven conditions involving various ambient temperatures (T a at 50% RH) and preheating designed to manipulate the esophageal (T es ) and mean skin ð " T sk Þ temperatures at _ V O 2max . The conditions were: 25°C, no preheating (control); 25, 35, 40, and 45°C, with exerciseinduced preheating by a 20-min walk at $33% of control _ V O 2max ; 45°C, no preheating; and 45°C, with passive preheating during which T es and "
European Geriatric Medicine, 2013
ABSTRACT Background Regular physical activity (PA) and nutritional counseling can reduce weight a... more ABSTRACT Background Regular physical activity (PA) and nutritional counseling can reduce weight and trunk fat accumulation and influence cardiometabolic factors. Methods This study was an exercise training and nutritional counseling intervention, conducted in two 6-month phases. Participants were assessed at baseline and at 6 and 12 months. Participants (54 males and 63 females aged 71–90) were randomized into immediate exercise training group (Group 1) and delayed exercise training group (Group 2). At time-point 2, the groups crossed over. Results After the exercise training-phase by Group 1, a statistically significant increase (P < 0.05) was seen in physical activity (PA), energy intake, and total lean mass. A significant decrease was seen in weight, total fat mass, trunk fat mass, waist circumference, and blood pressure. At the 6-month follow-up, Group 1 saw a significant decrease in PA, energy intake, total lean mass and blood pressure. A significant increase was seen in waist circumference and total fat mass. After the 6-month control phase by Group 2, a significant decrease was measured in PA, systolic blood pressure, total fat mass, fat mass of the trunk and waist circumference. After a delayed 6-month exercise training-phase by Group 2, a significant increase was measured in PA, and a decrease in weight, total fat mass, trunk fat mass, waist circumference, blood pressure and triglyceride. Conclusion Our findings suggest that positive improvements in body composition and cardiometabolic factors in old people may be achieved by systematic exercise training in combination with nutrition counseling. This should be considered as an integral part of the health care system.
PLOS ONE, 2015
The interaction between fatness, fitness, and C-reactive protein (CRP) in adolescents is not well... more The interaction between fatness, fitness, and C-reactive protein (CRP) in adolescents is not well characterized but may be important to prevent low grade inflammation. The purpose of this study was to assess the relationship between adiposity, different expressions of fitness, and CRP in late adolescence using direct measures of fitness and fatness. Anthropometric measurements were taken on 245 eighteen-year-old participants (116 girls). Fasting CRP, glucose, and insulin were measured and homeostatic model assessment (HOMA) calculated. Body composition was estimated via dual energy X-ray absorptiometry. Fitness was assessed with maximal oxygen uptake (VO2max) during a treadmill test and also expressed relative to the fat-free mass (VO2maxFFM). Prevalence of overweight/obesity based on body mass index (BMI) was 20.7% and 25.6% among girls and boys, respectively (p = 0.407), but 42.5% and 58.1% when based on body fat percentage (%fat, p = 0.015). Higher proportion of boys (81.3%) than girls (54.5%) were highly fit (p&amp;amp;amp;amp;amp;amp;amp;lt;0.001), but the percentage of girls with high levels of CRP was greater (12.1% vs 6.2%, p = 0.028). Adiposity, indicated with BMI, waist circumference, fat mass, android fat mass (aFM), or %fat, was positively associated with CRP independent of VO2max (r = 0.13-0.18, p&amp;amp;amp;amp;amp;amp;amp;lt;0.05) and VO2maxFFM (r = 0.24-0.32, p&amp;amp;amp;amp;amp;amp;amp;lt;0.001). VO2max, was negatively associated with CRP independent only of BMI and waist circumference (r = -0.21, p = 0.001), but not %fat, fat mass or aFM (r = -0.08 to -0.12, p&amp;amp;amp;amp;amp;amp;amp;gt;0.05). VO2maxFFM was unrelated to CRP with (r = -0.07 to -0.11, p&amp;amp;amp;amp;amp;amp;amp;gt;0.05) or without (r = -0.10, p = 0.142) adjustment for adiposity. Additional adjustment for HOMA did not change any of the relationships, although the coefficients were attenuated. Fatness has a greater association with CRP than fitness in late adolescence. However, VO2maxFFM, which is truly independent of adiposity, is unrelated to CRP, indicating that the effects of fitness might be mediated via the fatness component embedded in fitness expressed relative to body mass.
Medicine and Science in Sports and Exercise, 2008
Pediatric exercise science, 2008
The purpose of this study was to validate an equation that has been used to predict peak oxygen u... more The purpose of this study was to validate an equation that has been used to predict peak oxygen uptake (VO2peak) and, if invalid, to develop a new equation predicting VO2peak from performance on a cycle ergometer test. Forty-five 9- and 15-year-old children underwent a VO2peak test and were randomized into developmental (DEV) and cross-validation (C-V) groups. The equation under validation, which requires knowledge of resting energy expenditure (REE), underestimated VO2peak (p < .05), but once adjusted with a new parameter calculated in DEV, it cross-validated well (rYY' = .98, SE = .18 L . min-1). The accuracy of a new prediction equation built in DEV, not using REE, was confirmed in C-V (rYY' = .98, SE = .17 L . min-1) and the slope and intercept were not different from the line of identity (p < .05). VO2peak in schoolchildren can be predicted with good accuracy from an equation based on the whole sample [VO2peak = -1.5986 + 0.0115 . (maximal power output) + 0.0109 ....
International journal of obesity (2005), 2006
To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 19... more To investigate the prevalence and tracking of overweight and obesity in childhood cohorts born 1988 and 1994 in a population of high birth weight. Icelandic cohorts born in 1988 and 1994. Out of 1328, 9- and 15-year-old children from 18 randomly selected schools all over Iceland, 934 participated (71%). Height and mass were measured by the investigators. Also, height and mass at birth, and at age 2.5, 6, 9, and 12 years, were collected from maternity wards and school health registers. The prevalence of overweight children ranged from 10.1% for 2.5-year-olds to 18.7% for 9-year-olds. No difference was observed between the two cohorts or sex. The prevalence of obesity in the 1994 cohort (4.3%) was significantly higher (P = 0.01) at age 6 years, compared to the 1988 cohort (1.1%). The children who were overweight at age 2.5 years were more likely to be overweight at age 6 (OR=12.2) and 9 years (OR=4.9), but not significantly at age 12 or 15 years, compared with normal weight 2.5-year-o...
Journal of applied physiology (Bethesda, Md. : 1985), 2003
The purpose of this study was to examine the effect of resistance exercise on postprandial lipemi... more The purpose of this study was to examine the effect of resistance exercise on postprandial lipemia. Fourteen young men and women participated in each of three treatments: 1) control (Con), 2) resistance exercise (RE), and 3) aerobic exercise (AE) estimated to have an energy expenditure (EE) equal that for RE. Each trial consisted of performing a treatment on day 1 and ingesting a fat-tolerance test meal 16 h later (day 2). Resting metabolic rate and fat oxidation were measured at baseline and at 3 and 6 h postprandial on day 2. Blood was collected at baseline and at 0.5, 1, 2, 3, 4, 5, and 6 h after meal ingestion. RE and AE were similar in EE [1.7 +/- 0.1 vs. 1.6 +/- 0.1 (SE) MJ, respectively], as measured by using the Cosmed K4b(2). Baseline triglycerides (TG) were significantly lower after RE than after Con (19%) and AE (21%). Furthermore, the area under the postprandial response curve for TG, adjusted for baseline differences, was significantly lower after RE than after Con (14%...
Journal of applied physiology (Bethesda, Md. : 1985), 2003
We tested the hypothesis that elevation in heart rate (HR) during submaximal exercise in the heat... more We tested the hypothesis that elevation in heart rate (HR) during submaximal exercise in the heat is related, in part, to increased percentage of maximal O(2) uptake (%Vo(2 max)) utilized due to reduced maximal O(2) uptake (Vo(2 max)) measured after exercise under the same thermal conditions. Peak O(2) uptake (Vo(2 peak)), O(2) uptake, and HR during submaximal exercise were measured in 22 male and female runners under four environmental conditions designed to manipulate HR during submaximal exercise and Vo(2 peak). The conditions involved walking for 20 min at approximately 33% of control Vo(2 max) in 25, 35, 40, and 45 degrees C followed immediately by measurement of Vo(2 peak) in the same thermal environment. Vo(2 peak) decreased progressively (3.77 +/- 0.19, 3.61 +/- 0.18, 3.44 +/- 0.17, and 3.13 +/- 0.16 l/min) and HR at the end of the submaximal exercise increased progressively (107 +/- 2, 112 +/- 2, 120 +/- 2, and 137 +/- 2 beats/min) with increasing ambient temperature (T(a))...
American journal of human biology : the official journal of the Human Biology Council, 2000
This study used estimates of body composition from a four-component model (%Fat(d,w,m)) to determ... more This study used estimates of body composition from a four-component model (%Fat(d,w,m)) to determine whether the assumed density (D(ffm)) and the composition of the fat-free mass (FFM), and estimates of body composition from methods based on two- and three-component models are valid in distance runners. Measures of body density (D(b)) by underwater weighing, total body water by deuterium dilution, and bone mineral by dual-energy X-ray absorptiometry (DXA) were obtained in 10 female and 12 male runners and an equal number of controls matched for age, height, weight, gender, and ethnicity. D(ffm) of the runners did not differ from 1.1 g.cm(-3) or from the controls even though the composition of the FFM differed from that assumed. Therefore, percentage of body fat (%Fat) from densitometry did not differ from %Fat(d,w,m) in the runners, although individual variation was substantial (-5.3 to 3.0% body mass, SD(diff) = 2.1% body mass). Three-component model estimates of %Fat from D(b) and...
International journal of sport nutrition and exercise metabolism, 2009
This experiment examined the effect of a moderate dose of caffeine on quadriceps muscle pain duri... more This experiment examined the effect of a moderate dose of caffeine on quadriceps muscle pain during a bout of high-intensity cycling in low- versus high-caffeine-consuming males. College-age men who were low (< or =100 mg/day; n = 12) or high (> or =400 mg/day; n = 13) habitual caffeine consumers ingested caffeine (5 mg/kg body weight) or a placebo in a counterbalanced order and 1 hr later completed 30 min of cycle ergometry at 75-77% of peak oxygen consumption. Perceptions of quadriceps muscle pain, as well as oxygen consumption, heart rate, and work rate, were recorded during both bouts of exercise. Caffeine ingestion resulted in a statistically significant and moderate reduction in quadriceps muscle-pain-intensity ratings during the 30-min bout of high-intensity cycle ergometry compared with placebo ingestion in both low (d = -0.42) and high (d = -0.55) caffeine consumers. The results suggest that caffeine ingestion is associated with a moderate hypoalgesic effect during hi...
Læknablađiđ, 2012
The purpose of the study was to examine metabolic risk factors among 18 year old high-school stud... more The purpose of the study was to examine metabolic risk factors among 18 year old high-school students and compare students attending vocational and traditional schools. Participants (147 boys and 130 girls) were randomly selected. Physical activity (PA) was measured with pedometers and aerobic fitness (fitness) with maximal oxygen uptake test on a treadmill. Height, weight, waist circumference (WC), and body mass index (BMI) were measured and percentage body fat (%Fat) assessed with dual energy X-ray absorptiometry. Resting blood pressure (BP) and serum lipids and glucose were measured. According to BMI, 23% of the students were overweight/obese, 20% had elevated WC, and 51% increased %Fat. In addition, 11% of the students had high-density lipoprotein below recommended levels, and 8% had low-density lipoprotein and 9% triglycerides above advised values. Finally, 10% had borderline or high systolic BP. In contrast, 84% of the students had fair or higher levels of fitness, although on...
Læknablađiđ, 2013
Good functional performance in elderly people greatly improves their changes of independence and ... more Good functional performance in elderly people greatly improves their changes of independence and well-being. Conversely, bad functional performance can impair their capability of managing the activities of daily life.. The main goal of this study was to investigate the effects of a 6-months' multimodal training intervention on the physical performance of males and females, possible gender differences and the outcome 6 and 12 months after its completion. This study examined 71-90 year old healthy seniors (n=117) participating in the AGES Reykjavik Study. It was a randomized and controlled cross-over trial, conducted in three 6-months' phases (time-points). After enrollment and baseline assessments, the study group was divided in two. Group 1 received 6-months' training while group 2 served as a control. In the second 6 months' phase, group 1 received no formal training while group 2 did. In the third phase, neither group received training. The groups' physical con...
To compare the effect of hyperthermia on maximal oxygen uptake ( _ V O 2max ) in men and women, _... more To compare the effect of hyperthermia on maximal oxygen uptake ( _ V O 2max ) in men and women, _ V O 2max was measured in 11 male and 11 female runners under seven conditions involving various ambient temperatures (T a at 50% RH) and preheating designed to manipulate the esophageal (T es ) and mean skin ð " T sk Þ temperatures at _ V O 2max . The conditions were: 25°C, no preheating (control); 25, 35, 40, and 45°C, with exerciseinduced preheating by a 20-min walk at $33% of control _ V O 2max ; 45°C, no preheating; and 45°C, with passive preheating during which T es and "