Fluid ingestion during exercise increases skin blood flow independent of increases in blood volume

1992 ◽  
Vol 73 (3) ◽  
pp. 903-910 ◽  
Author(s):  
S. J. Montain ◽  
E. F. Coyle
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Blood Volume ◽  
Skin Blood Flow ◽  
Forearm Blood Flow ◽  
Sodium Concentration ◽  
Maximum Oxygen Uptake ◽  
Fluid Replacement ◽  
Fluid Ingestion ◽  
Cardiovascular Drift

The purpose of this experiment was to determine whether fluid ingestion attenuates the hyperthermia and cardiovascular drift that occurs during exercise dehydration due to increases in blood volume. In addition, forearm blood flow, which is indicative of skin blood flow, was measured to determine whether the attenuation of hyperthermia and cardiovascular drift during exercise with fluid ingestion is due to higher skin blood flow. On three different occasions, seven trained cyclists [mean age, body weight, and maximum oxygen uptake: 23 +/- 3 yr, 73.9 +/- 10.5 kg, and 4.75 +/- 0.34 (SD) l/min, respectively] cycled at a power output equal to 62–67% maximum oxygen uptake for 2 h in a warm environment (33 degrees C, 50% relative humidity, wind speed 2.5 m/s). During exercise, they randomly received no fluid (NF) or a volume of a carbohydrate-electrolyte fluid replacement solution (FR) sufficient to replace 80 +/- 2% of sweat loss or were intravenously infused with 5.3 ml/kg of a blood volume expander (BVX; 6% dextran in saline). The infusion of 398 +/- 23 ml of BVX maintained blood volume at levels similar to that when 2,404 +/- 103 ml of fluid were ingested during FR and greater than that when no fluid was ingested during the 2nd h of exercise (P less than 0.05). However, BVX and NF resulted in similar esophageal and rectal temperatures, forearm blood flow, and elevations in serum osmolality and sodium concentration during 2 h of exercise.(ABSTRACT TRUNCATED AT 250 WORDS)

Influence of graded dehydration on hyperthermia and cardiovascular drift during exercise

1992 ◽  
Vol 73 (4) ◽  
pp. 1340-1350 ◽  
Author(s):  
S. J. Montain ◽  
E. F. Coyle
Keyword(s):  
Blood Flow ◽  
Prolonged Exercise ◽  
Forearm Blood Flow ◽  
Sweat Rate ◽  
Sodium Concentration ◽  
O2 Consumption ◽  
Esophageal Temperature ◽  
Warm Environment ◽  
Cardiovascular Drift ◽  
Highly Correlated

This investigation determined the effect of different rates of dehydration, induced by ingesting different volumes of fluid during prolonged exercise, on hyperthermia, heart rate (HR), and stroke volume (SV). On four different occasions, eight endurance-trained cyclists [age 23 +/- 3 (SD) yr, body wt 71.9 +/- 11.6 kg, maximal O2 consumption 4.72 +/- 0.33 l/min] cycled at a power output equal to 62-67% maximal O2 consumption for 2 h in a warm environment (33 degrees C dry bulb, 50% relative humidity, wind speed 2.5 m/s). During exercise, they randomly received no fluid (NF) or ingested a small (SF), moderate (MF), or large (LF) volume of fluid that replaced 20 +/- 1, 48 +/- 1, and 81 +/- 2%, respectively, of the fluid lost in sweat during exercise. The protocol resulted in graded magnitudes of dehydration as body weight declined 4.2 +/- 0.1, 3.4 +/- 0.1, 2.3 +/- 0.1, and 1.1 +/- 0.1%, respectively, during NF, SF, MF, and LF. After 2 h of exercise, esophageal temperature (Tes), HR, and SV were significantly different among the four trials (P < 0.05), with the exception of NF and SF. The magnitude of dehydration accrued after 2 h of exercise in the four trials was linearly related with the increase in Tes (r = 0.98, P < 0.02), the increase in HR (r = 0.99, P < 0.01), and the decline in SV (r = 0.99, P < 0.01). LF attenuated hyperthermia, apparently because of higher skin blood flow, inasmuch as forearm blood flow was 20–22% higher than during SF and NF at 105 min (P < 0.05). There were no differences in sweat rate among the four trials. In each subject, the increase in Tes from 20 to 120 min of exercise was highly correlated to the increase in serum osmolality (r = 0.81-0.98, P < 0.02-0.19) and the increase in serum sodium concentration (r = 0.87-0.99, P < 0.01-0.13) from 5 to 120 min of exercise. In summary, the magnitude of increase in core temperature and HR and the decline in SV are graded in proportion to the amount of dehydration accrued during exercise.

scholarly journals Vastus lateralis oxygenation during prolonged cycling in healthy males

2006 ◽  
Vol 31 (1) ◽  
pp. 48-55 ◽  
Author(s):  
Kotaro Kawaguchi ◽  
Yukiko Hayashi ◽  
Kiyokazu Sekikawa ◽  
Mitsuru Tabusadani ◽  
Tsutomu Inamizu ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Oxygen Uptake ◽  
Blood Volume ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Vastus Lateralis ◽  
Muscle Oxygenation ◽  
Cardiovascular Drift ◽  
Systemic Oxygen ◽  
The Relationship

This study examined the relationship between acute cardiorespiratory and muscle oxygenation and blood volume changes during prolonged exercise. Eight healthy male volunteers (mean maximum oxygen uptake ([Formula: see text]O2max) = 41.6 ± 2.4 mL/kg/min) performed 60 min submaximal cycling at 50% [Formula: see text]O2max. Oxygen uptake ([Formula: see text]O2) was measured by indirect spirometry, cardiac output (CO) was estimated using a PortapresTM, and right vastus lateralis oxyhemoglobin/ myoglobin (oxyHb/Mb), deoxyhemoglobin/myoglobin (deoxyHb/Mb), and total hemoglobin/myoglobin (total Hb/Mb) were recorded using near-infrared spectroscopy (NIRS). After 40 min of exercise, there was a significant increase in [Formula: see text]O2 due to a significantly higher arteriovenous oxygen difference ((a - v)O2diff). After 30 min of exercise CO remained unchanged, but there was a significant decrease in stroke volume and a proportionate increase in heart rate, thus indicating the occurrence of cardiovascular drift. During the first few minutes of exercise, there was a decline in oxyHb/Mb and total Hb/Mb, whereas deoxyHb/Mb remained unchanged. Thereafter, oxyHb/Mb and total Hb/Mb increased systematically until the termination of exercise while deoxyHb/Mb declined. After 40 min of exercise, these changes were significantly different from the baseline values. There were no significant correlations between the changes in the NIRS variables and systemic [Formula: see text]O2 or mixed (a - v)O2diff during exercise. These results suggest that factors other than localized changes in muscle oxygenation and blood volume account for the increased [Formula: see text]O2 during prolonged submaximal exercise. Key words: near infrared spectroscopy, cardiovascular drift, systemic oxygen consumption.

Cardiovascular drift can occur without a concomitant increase in skin blood flow

1998 ◽  
pp. 104-109
Author(s):  
Michael J. Buono ◽  
Jay H. Heaney ◽  
Julia A. Cline ◽  
Sandra G. Leichliter
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Concomitant Increase ◽  
Cardiovascular Drift

Interactions between local and reflex influences on human forearm skin blood flow

1976 ◽  
Vol 41 (6) ◽  
pp. 826-831 ◽  
Author(s):  
J. M. Johnson ◽  
G. L. Brengelmann ◽  
L. B. Rowell
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Forearm Blood Flow ◽  
Lower Body Negative Pressure ◽  
Muscle Blood Flow ◽  
Whole Body ◽  
Vasoconstrictor Response ◽  
Human Forearm ◽  
Forearm Skin ◽  
Forearm Muscle

A three-part experiment was designed to examine interactions between local and reflex influences on forearm skin blood flow (SkBF). In part I locally increasing arm skin temperature (Tsk) to 42.5 degrees C was not associated with increases in underlying forearm muscle blood flow, esophageal temperature (Tes), or forearm blood flow in the contralateral cool arm. In part II whole-body Tsk was held at 38 or 40 degrees C and the surface temperature of one arm held at 38 or 42 degrees C for prolonged periods. SkBF in the heated arm rose rapidly with the elevation in body Tsk and arm Tsk continued to rise as Tes rose. SkBF in the arm kept at 32 degrees C paralleled rising Tes. In six studies, SkBF in the cool arm ultimately converged with SkBF in the heated arm. In eight other studies, heated arm SkBF maintained an offset above cool arm SkBF throughout the period of whole-body heating. In part III, local arm Tsk of 42.5 degrees C did not abolish skin vasoconstrictor response to lower body negative pressure. We conclude that local and reflex influences to skin interact so as to modify the degree but not the pattern of skin vasomotor response.

Cutaneous blood flow during exercise is higher in endurance-trained humans

2000 ◽  
Vol 88 (2) ◽  
pp. 738-744 ◽  
Author(s):  
Ricardo G. Fritzsche ◽  
Edward F. Coyle
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Forearm Blood Flow ◽  
Peak Oxygen Uptake ◽  
Metabolic Rates ◽  
Esophageal Temperature ◽  
Cutaneous Blood Flow ◽  
Cycling Exercise ◽  
C 50 ◽  
Cutaneous Blood

This study determined whether cutaneous blood flow during exercise is different in endurance-trained (Tr) compared with untrained (Untr) subjects. Ten Tr and ten Untr men (62.4 ± 1.7 and 44.2 ± 1.8 ml ⋅ kg− 1 ⋅ min− 1, respectively; P < 0.05) underwent three 20-min cycling-exercise bouts at 50, 70, and 90% peak oxygen uptake in this order, with 30 min rest in between. The environmental conditions were neutral (∼23–24°C, 50% relative humidity, front and back fans at 2.5 m/s). Because of technical difficulties, only seven Tr and seven Untr subjects completed all forearm blood flow and laser-Doppler cutaneous blood flow (CBF) measurements. Albeit similar at rest, at the end of all three exercise bouts, forearm blood flow was ∼40% higher in Tr compared with Untr subjects (50%: 4.64 ± 0.50 vs. 3.17 ± 0.20, 70%: 6.17 ± 0.61 vs. 4.41 ± 0.37, 90%: 6.77 ± 0.62 vs. 5.01 ± 0.37 ml ⋅ 100 ml− 1 ⋅ min− 1, respectively; n = 7; all P < 0.05). CBF was also higher in Tr compared with Untr subjects at all relative intensities ( n = 7; all P < 0.05). However, esophageal temperature was not different in Tr compared with Untr subjects at the end of any of the aforementioned exercise bouts (50%: 37.8 ± 0.1 vs. 37.9 ± 0.1°C, 70%: 38.1 ± 0.1 vs. 38.1 ± 0.1°C, and 90%: 38.8 ± 0.1 vs. 38.6 ± 0.1°C, respectively). We conclude that a higher CBF may allow Tr subjects to achieve an esophageal temperature similar to that of Untr, despite their higher metabolic rates and thus higher heat production rates, during exercise at 50–90% peak oxygen uptake.

Age alters regional distribution of blood flow during moderate-intensity exercise

1995 ◽  
Vol 79 (4) ◽  
pp. 1112-1119 ◽  
Author(s):  
W. L. Kenney ◽  
C. W. Ho
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Renal Blood Flow ◽  
Skin Blood Flow ◽  
Forearm Blood Flow ◽  
Regional Distribution ◽  
Splanchnic Blood Flow ◽  
Moderate Intensity ◽  
Plasma Norepinephrine ◽  
Moderate Intensity Exercise

During dynamic exercise in warm environments, requisite increases in skin and active muscle blood flows are supported by increasing cardiac output (Qc) and redistributing flow away from splanchnic and renal circulations. To examine the effect of age on these responses, six young (Y; 26 +/- 2 yr) and six older (O; 64 +/- 2 yr) men performed upright cycle exercise at 35 and 60% of peak O2 consumption (VO2peak) in 22 and 36 degrees C environments. To further isolate age, the two age groups were closely matched for VO2peak, weight, surface area, and body composition. Measurements included heart rate, Qc (CO2 rebreathing), skin blood flow (from increases in forearm blood flow (venous occlusion plethysmography), splanchnic blood flow (indocyanine green dilution), renal blood flow (p-amino-hippurate clearance), and plasma norepinephrine concentration. There were no significant age differences in Qc; however, in both environments the O group maintained Qc at a higher stroke volume and lower heart rate. At 60% VO2peak, forearm blood flow was significantly lower in the O subjects in each environment. Splanchnic blood flow fell (by 12–14% in both groups) at the lower intensity, then decreased to a greater extent at 60% VO2peak in Y than in O subjects (e.g., -45 +/- 2 vs. -33 +/- 3% for the hot environment, P < 0.01). Renal blood flow was lower at rest in the O group, remained relatively constant at 35% VO2peak, then decreased by 20–25% in both groups at 60% VO2peak. At 60% VO2peak, 27 and 37% more total blood flow was redistributed away from these two circulations in the Y than in the O group at 22 and 36 degrees, respectively. It was concluded that the greater increase in skin blood flow in Y subjects is partially supported by a greater redistribution of blood flow away from splanchnic and renal vascular beds.

Stroke volume during exercise: interaction of environment and hydration

2000 ◽  
Vol 278 (2) ◽  
pp. H321-H330 ◽  
Author(s):  
José González-Alonso ◽  
Ricardo Mora-Rodríguez ◽  
Edward F. Coyle
Keyword(s):  
Heart Rate ◽  
Blood Flow ◽  
Body Weight ◽  
Stroke Volume ◽  
Blood Volume ◽  
Skin Blood Flow ◽  
Body Weight Loss ◽  
Cold Environment ◽  
Esophageal Temperature ◽  
Trained Subjects

Euhydrated and dehydrated subjects exercised in a hot and a cold environment with our aim to identify factors that relate to reductions in stroke volume (SV). We hypothesized that reductions in SV with heat stress are related to the interaction of several factors rather than the effect of elevated skin blood flow. Eight male endurance-trained cyclists [maximal O2 consumption (V˙o 2 max) 4.5 ± 0.1 l/min; means ± SE] cycled for 30 min (72%V˙o 2 max) in the heat (H; 35°C) or the cold (C; 8°C) when euhydrated or dehydrated by 1.5, 3.0, or 4.2% of their body weight. When euhydrated, SV and esophageal temperature (Tes 38.2–38.3°C) were similar in H and C, whereas skin blood flow was much higher in H vs. C (365 ± 64% higher; P < 0.05). With each 1% body weight loss, SV declined 6.4 ± 1.3 ml (4.8%) in H and 3.4 ± 0.4 ml (2.5%) in C, whereas Tes increased 0.21 ± 0.02 and 0.10 ± 0.02°C in H and C, respectively ( P < 0.05). However, reductions in SV were not associated with increases in skin blood flow. The reduced SV was highly associated with increased heart rate and reduced blood volume in both H ( R = 0.96; P < 0.01) and C ( R = 0.85; P < 0.01). In conclusion, these results suggest that SV is maintained in trained subjects during exercise in euhydrated conditions despite large differences in skin blood flow. Furthermore, the lowering of SV with dehydration appears largely related to increases in heart rate and reductions in blood volume.

Control of skin blood flow in the neutral zone of human body temperature regulation

1996 ◽  
Vol 80 (4) ◽  
pp. 1249-1257 ◽  
Author(s):  
M. V. Savage ◽  
G. L. Brengelmann
Keyword(s):  
Blood Flow ◽  
Skin Blood Flow ◽  
Inverse Relationship ◽  
Forearm Blood Flow ◽  
Wave Pattern ◽  
The Body ◽  
Reflex Response ◽  
Neutral Zone ◽  
Human Body Temperature ◽  
Skin Temperatures

In humans, matching of heat loss and heat production in the “neutral” zone, defined operationally in terms of a range of skin temperatures (Tsk), is accomplished by regulation of skin blood flow (SkBF). Our studies were designed to reveal the characteristics of control of SkBF [from measurements of forearm blood flow (FBF)] in this zone. We controlled the temperature of water sprayed on most of the body of supine men and women at 33 or 35 degrees C in a square-wave pattern (15 min at each temperature) or a step pattern (60 min at 33 degrees C separated by short periods at 35 degrees C). FBF followed Tsk (0.5 ml.min-1.degrees C-1). Esophageal temperature changed approximately 0.11 degrees C with each 2 degrees C change in Tsk, falling with Tsk increase and vice versa. Little influence on FBF, < 0.1 ml.min-1.100 ml-1. degrees C-1, was observed when only the forearm was sprayed with 33 and 35 degrees C water. We conclude that SkBF control in the 33-35 degree C range of Tsk is dominated by the feedforward reflex influence of Tsk on SkBF. The reflex response overcompensates for the effect of Tsk on thermal balance in the neutral zone, so that equilibrium core temperature has an inverse relationship to Tsk.

PANAX NOTOGINSENG SUPPLEMENT IMPROVES ENDURANCE AND OXYGEN UPTAKE BUT NOT SKIN BLOOD FLOW

2003 ◽  
Vol 35 (Supplement 1) ◽  
pp. S268
Author(s):  
M T.C. Liang ◽  
T D. Podolka ◽  
L Darby ◽  
W Chuang
Keyword(s):  
Blood Flow ◽  
Oxygen Uptake ◽  
Skin Blood Flow ◽  
Panax Notoginseng
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