Protein and carbohydrate supplementation during 5-day aerobic training enhanced plasma volume expansion and thermoregulatory adaptation in young men

We examined whether protein and carbohydrate (CHO) supplementation during 5-day training enhanced plasma volume (PV) expansion and thermoregulatory and cardiovascular adaptations in young men. Eighteen men [age 23 ± 4 (SD) yr] were divided into two groups according to supplements: placebo (CNT: 0.93 kcal/kg, 0.00 g protein/kg, n = 9) and protein and CHO (Pro-CHO: 3.6 kcal/kg, 0.36 protein/kg, n = 9). Subjects in both groups performed a cycling exercise at 70% peak oxygen consumption rate (V̇o2peak), 30 min/day, for 5 consecutive days at 30°C ambient temperature and 50% relative humidity and took either a placebo or Pro-CHO within 10 min after exercise for each day. Before and after training, PV at rest, heart rate (HR), and esophageal temperature (Tes) during 30-min exercise at 65% of pretraining V̇o2peak in the same condition as training were determined. Also, the sensitivity of the chest sweat rate (ΔSR/ΔTes) and forearm vascular conductance (ΔFVC/ΔTes) in response to increased Tes were determined. After training, PV and cardiac stroke volume (SV) at rest increased in both groups ( P < 0.001) but the increases were twofold higher in Pro-CHO than CNT ( P = 0.007 and P = 0.078, respectively). The increases in HR from 5 to 30 min and Tes from 0 to 30 min of exercise were attenuated after training in both groups with greater attenuation in Pro-CHO than CNT ( P = 0.002 and P = 0.072, respectively). ΔSR/ΔTes increased in CNT ( P = 0.052) and Pro-CHO ( P < 0.001) and the increases were higher in Pro-CHO than CNT ( P = 0.018). ΔFVC/ΔTes increased in Pro-CHO ( P < 0.001), whereas not in CNT ( P = 0.16). Thus protein-CHO supplementation during 5-day training enhanced PV expansion and thermoregulatory adaptation and, thereby, the reduction in heat and cardiovascular strain in young men.

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Impact of protein and carbohydrate supplementation on plasma volume expansion and thermoregulatory adaptation by aerobic training in older men

Journal of Applied Physiology ◽

10.1152/japplphysiol.91265.2008 ◽

2009 ◽

Vol 107 (3) ◽

pp. 725-733 ◽

Cited By ~ 39

Author(s):

Kazunobu Okazaki ◽

Takashi Ichinose ◽

Hiroyuki Mitono ◽

Mian Chen ◽

Shizue Masuki ◽

...

Keyword(s):

G Protein ◽

Plasma Volume ◽

Aerobic Training ◽

Sweat Rate ◽

Interactive Effect ◽

Older Men ◽

Peak Oxygen Consumption ◽

Plasma Volume Expansion ◽

Anthropometric Measures ◽

Before And After

We examined whether protein-carbohydrate (CHO) supplementation immediately after exercise each day during aerobic training facilitated plasma volume (PV) expansion and thermoregulatory and cardiovascular adaptations in older men. Fourteen moderately active older men [68 ± 5 (SD) yr] were divided into two groups so as to have no significant differences in anthropometric measures, PV, and peak oxygen consumption rate (V̇o2peak). Each group was provided with a mixture of protein and CHO (3.2 kcal, 0.18 g protein/kg body wt, Pro-CHO, n = 7) or a non-protein and low-calorie placebo (0.5 kcal, 0 g protein/kg body wt, CNT, n = 7) immediately after cycling exercise (60–75% V̇o2peak, 60 min/day, 3 days/wk) each day for 8 wk at ∼19°C ambient temperature (Ta) and ∼43% relative humidity (RH). Before and after training, we measured PV, cardiac stroke volume (SV), and esophageal temperature (Tes) during 20-min exercise at 60% of pretraining V̇o2peak at 30°C Ta and 50% RH. Moreover, we determined the sensitivity of the chest sweat rate (ΔSR/ΔTes) and forearm vascular conductance (ΔFVC/ΔTes) in response to increased Tes during exercise. After training, PV increased by ∼6% in Pro-CHO ( P < 0.001), with an ∼10% increase in SV during exercise ( P < 0.001), but not in CNT ( P > 0.07). ΔFVC/ΔTes increased by 80% and ΔSR/ΔTes by 18% in Pro-CHO (both P < 0.01) but not in CNT ( P > 0.07). Moreover, we found a significant interactive effect of group × training on PV, SV, and ΔFVC/ΔTes (all P < 0.02) but with no significant effect of group ( P > 0.4), suggesting that the supplement enhanced these responses to aerobic training. Thus postexercise protein-CHO supplementation during training caused PV expansion and facilitated thermoregulatory and cardiovascular adaptations, possibly providing a new training regimen for older men.

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Effects of hypohydration on thermoregulation during exercise before and after 5-day aerobic training in a warm environment in young men

Journal of Applied Physiology ◽

10.1152/japplphysiol.01193.2010 ◽

2011 ◽

Vol 110 (4) ◽

pp. 972-980 ◽

Cited By ~ 26

Author(s):

Shigeki Ikegawa ◽

Yoshi-ichiro Kamijo ◽

Kazunobu Okazaki ◽

Shizue Masuki ◽

Yoshiyuki Okada ◽

...

Keyword(s):

Aerobic Training ◽

Sweat Rate ◽

Combined Treatment ◽

Young Men ◽

Atmospheric Temperature ◽

Peak Oxygen Consumption ◽

Warm Environment ◽

Cutaneous Vasodilation ◽

Before And After ◽

Forearm Skin

We examined whether enhanced cardiovascular and thermoregulatory responses during exercise after short-term aerobic training in a warm environment were reversed when plasma volume (PV) expansion was reversed by acute isotonic hypohydration. Seven young men performed aerobic training at the 70% peak oxygen consumption rate (V̇o2peak) at 30°C atmospheric temperature and 50% relative humidity, 30 min/day for 5 days. Before and after training, we performed the thermoregulatory response test while measuring esophageal temperature (Tes), forearm skin vascular conductance, sweat rate (SR), and PV during 30 min exercise at the metabolic rate equivalent to pretraining 65% V̇o2peak in euhydration under the same environment as during training in four trials (euhydration and hypohydration, respectively). Hypohydration targeting 3% body mass was attained by combined treatment with low-salt meals to subjects from ∼48 h before the test and administration of a diuretic ∼4 h before the test. After training, the Tes thresholds for cutaneous vasodilation and sweating decreased by 0.3 and 0.2°C ( P = 0.008 and 0.012, respectively) when PV increased by ∼10%. When PV before and after training was reduced to a similar level, ∼10% reduction from that in euhydration before training, the training-induced reduction in the threshold for cutaneous vasodilation increased to a level similar to hypohydration before training ( P = 0.093) while that for sweating remained significantly lower than that before training ( P = 0.004). Thus the enhanced cutaneous vasodilation response after aerobic training in a warm environment was reversed when PV expansion was reversed while the enhanced SR response remained partially.

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Mechanism for the posture-specific plasma volume increase after a single intense exercise protocol

Journal of Applied Physiology ◽

10.1152/jappl.1999.86.3.867 ◽

1999 ◽

Vol 86 (3) ◽

pp. 867-873 ◽

Cited By ~ 29

Author(s):

Kei Nagashima ◽

Gary W. Mack ◽

Andrew Haskell ◽

Takeshi Nishiyasu ◽

Ethan R. Nadel

Keyword(s):

Plasma Volume ◽

Volume Expansion ◽

Venous Pressure ◽

Urine Volume ◽

Peak Oxygen Consumption ◽

Plasma Volume Expansion ◽

Plasma Albumin ◽

Postural Changes ◽

Albumin Content ◽

Exercise Induced

To test the hypothesis that exercise-induced hypervolemia is a posture-dependent process, we measured plasma volume, plasma albumin content, and renal function in seven healthy subjects for 22 h after single upright (Up) or supine (Sup) intense (85% peak oxygen consumption rate) exercise. This posture was maintained for 5 h after exercise. Plasma volume decreased during exercise but returned to control levels by 5 h of recovery in both postures. By 22 h of recovery, plasma volume increased 2.4 ± 0.8 ml/kg in Up but decreased 2.1 ± 0.8 ml/kg in Sup. The plasma volume expansion in Up was accompanied by an increase in plasma albumin content (0.11 ± 0.04 g/kg; P < 0.05). Plasma albumin content was unchanged in Sup. Urine volume and sodium clearance were lower in Up than Sup ( P < 0.05) by 5 h of recovery. These data suggest that increased plasma albumin content contributes to the acute phase of exercise-induced hypervolemia. More importantly, the mechanism by which exercise influences the distribution of albumin between extra- and intravascular stores after exercise is altered by posture and is unknown. We speculate that factors associated with postural changes (e.g., central venous pressure) modify the increase in plasma albumin content and the plasma volume expansion after exercise.

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Acute plasma volume expansion alters cardiovascular but not thermal function during moderate intensity prolonged exercise

Canadian Journal of Physiology and Pharmacology ◽

10.1139/y99-151 ◽

2000 ◽

Vol 78 (3) ◽

pp. 244-250 ◽

Cited By ~ 10

Author(s):

B D Roy ◽

H J Green ◽

S M Grant ◽

M A Tarnopolsky

Keyword(s):

Plasma Volume ◽

Volume Expansion ◽

Prolonged Exercise ◽

Peripheral Resistance ◽

Moderate Intensity ◽

Thermoregulatory Response ◽

Plasma Volume Expansion ◽

Cardiovascular Performance ◽

Before And After ◽

Similar Decrease

To investigate the hypothesis that the increase in plasma volume (PV) that typically occurs with training results in improved cardiovascular and thermal regulation during prolonged exercise, eight untrained males (Vo2peak = 3.52 ± 0.12 L·min-1) performed 90 min of cycle ergometry at 62% Vo2peak before and after acute PV expansion. Subjects were infused with a PV-expanding solution (dextran (6%) or Pentaspan (10%)) equivalent to 6.7 mL·kg-1 body mass (PVX) or acted as their own control (CON) in a randomized order. PVX resulted in a calculated 15.8% increase in resting PV, which relative to CON, was maintained throughout the exercise (P < 0.05). During PVX, heart rate was lower (P < 0.05) and stroke volume and cardiac output were higher (P < 0.05) during the exercise. Mean arterial pressure and total peripheral resistance, although altered by exercise (P < 0.05), were not different between the two conditions. Core temperature, which was progressively increased by the exercise (P < 0.01), was not affected by PVX. A similar decrease in body weight was observed between the conditions as a result of the exercise (P < 0.01). These results indicate that acute PVX alters cardiovascular performance without affecting the thermoregulatory response to prolonged cycle exercise.Key words: cardiovascular, prolonged exercise, acute plasma volume expansion, thermoregulation, hypervolemia.

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Responses to dry heat of men and women with similar aerobic capacities

Journal of Applied Physiology ◽

10.1152/jappl.1981.50.1.65 ◽

1981 ◽

Vol 50 (1) ◽

pp. 65-70 ◽

Cited By ~ 59

Author(s):

A. J. Frye ◽

E. Kamon

Keyword(s):

Heat Stress ◽

Menstrual Cycle ◽

Strain State ◽

Sweat Rate ◽

Stress Tests ◽

Ambient Conditions ◽

Men And Women ◽

Dry Heat ◽

Before And After ◽

Cardiovascular Strain

Four men and four women with similar VO2max (56.33 +/- 4.05 and 54.08 +/- 4.27 ml.kg-1.min-1, respectively) exercised up to 3 h at 30% VO2max during heat stress tests (HST) before and after acclimation to dry heat [dry-bulb temperature (Tdb)/wet-bulb temperature (Twb) = 48/25 degrees C]. Rectal (Tre), tympanic sweat on the chest (msw), and total sweat rate (Msw) were recorded. There were no differences in the responses of the women between phases of the menstrual cycle. Tre, Tty, Tsk, and Tdb at the onset of sweating were similar in both sexes before and after acclimation. The nonacclimated men had significantly higher Msw and slower rise in Tre as compared to the nonacclimated women. Following acclimation these differences were no longer evident. Acclimation produced an increase in Msw in both sexes that was characterized by an increase in sweating sensitivity (delta msw/delta Tre). It was concluded that sex alone does not determine responses to heat stress. Consideration should also be given to the relative cardiovascular strain, state of acclimation, and the ambient conditions.

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Physiological and hematologic responses to summer and winter dry-heat acclimation

Journal of Applied Physiology ◽

10.1152/jappl.1981.50.4.792 ◽

1981 ◽

Vol 50 (4) ◽

pp. 792-798 ◽

Cited By ~ 37

Author(s):

Y. Shapiro ◽

R. W. Hubbard ◽

C. M. Kimbrough ◽

K. B. Pandolf

Keyword(s):

Cell Volume ◽

Plasma Volume ◽

Volume Expansion ◽

Sweat Rate ◽

Heat Acclimation ◽

Red Cell ◽

Plasma Volume Expansion ◽

Set Point ◽

Dry Heat ◽

C 30

Differences between acclimation to heat at the end of winter (W) and at the end of summer (S) were studied on the same eight male volunteers. Subjects were exposed to 40 degrees C, 30% rh for 10 consecutive days on two separate occasions approximately 5 mo apart (S and W). Daily exposures lasted 120 min: 10 min rest, 50 min walking 1.34 m . s-1 on the level, 10 min rest, 50 min walking. During W acclimation, rectal temperature (Tre) and heart rate (HR) decreased, sweat rate (msw) remained unchanged, and plasma and red cell volume of the blood expanded. During S acclimation, HR decreased while Tre and msw remained unchanged, and plasma volume increased. The Tre of the acclimated subjects remained higher in W, and the msw lower, than in S. It was concluded that acclimation does not totally eliminate the seasonal differences in thermoregulatory set point and sweating sensitivity. Further, acclimation to a more severe heat did not lower the thermoregulatory set point that was achieved by natural acclimatization to a milder heat but affected the cardiovascular adjustment and caused greater plasma volume expansion. W acclimation caused both plasma and blood cell volume expansion, whereas S acclimation affected only plasma volume.

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Hydration Status in College Football Players during Consecutive Days of Twice-a-Day Preseason Practices

The American Journal of Sports Medicine ◽

10.1177/0363546504270999 ◽

2005 ◽

Vol 33 (6) ◽

pp. 843-851 ◽

Cited By ~ 52

Author(s):

Sandra Fowkes Godek ◽

Joseph J. Godek ◽

Arthur R. Bartolozzi

Keyword(s):

Body Weight ◽

Specific Gravity ◽

Core Temperature ◽

Plasma Volume ◽

Sweat Rate ◽

Urine Samples ◽

Urine Specific Gravity ◽

Football Players ◽

Urine Sodium ◽

Before And After

Background Football players lose 3.5 to 5 kg of body weight during preseason practices because of heavy sweating. This fluid may be difficult to replace when practices occur 2 times per day on consecutive days. Hypothesis Football players are hypohydrated during twice-a-day preseason training in a hot, humid environment. Study Design Descriptive laboratory study Methods In 10 college football players, body weight was measured, and blood and urine samples were obtained before and after practices on days 2 through 8 of preseason training. Baseline samples were obtained when subjects were euhydrated. Blood samples were used to calculate plasma volume changes. Urine samples were analyzed for specific gravity, sodium, and potassium. Sweat rate was calculated. Core temperature was monitored during half- and full-padded practices. Results Mean wet bulb temperatures were 23.3°C during morning practices and 23.7°C during afternoon practices. Plasma volume was below baseline on day 2 and expanded by day 6. Urine specific gravity was higher than baseline for 12 of 20 measurements over the 8 days. It was 1.0175 ± 0.006 at baseline but subsequently ranged from 1.0214 ± 0.007 to 1.0321 ± 0.004. Mean daily urine sodium dropped from baseline to day 2 (194 ± 43 vs 43 ± 38 mmol × L-1), remaining lower on days 3, 4, and 6 (40 ± 39, 39 ± 39, and 68 ± 40 mmol × L-1, respectively). Urine potassium was lower on days 6 and 8 compared with baseline and day 3. Body weight was below baseline before and after both daily practices. Core temperature was higher in full pads; sweat rate and body weight loss were not different between half and full pads. Conclusion Body weight, plasma volume, urine specific gravity, and urine sodium indicate that football players become dehydrated by day 2 of preseason training. Urine sodium increased to near baseline by day 8; urine specific gravity was elevated. Clinical Relevance Football players struggle to maintain euhydration during preseason twice-a-day sessions.

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Hypohydration and exercise: effects of heat acclimation, gender, and environment

Journal of Applied Physiology ◽

10.1152/jappl.1983.55.4.1147 ◽

1983 ◽

Vol 55 (4) ◽

pp. 1147-1153 ◽

Cited By ~ 74

Author(s):

M. N. Sawka ◽

M. M. Toner ◽

R. P. Francesconi ◽

K. B. Pandolf

Keyword(s):

Aerobic Power ◽

Sweat Rate ◽

Heat Rate ◽

Heat Acclimation ◽

Experimental Conditions ◽

Exercise Tests ◽

Men And Women ◽

Before And After ◽

Hot Environments ◽

Cardiovascular Strain

This study examined the effects of heat acclimation and subject gender on treadmill exercise in comfortable (20 degrees C, 40% rh), hot-dry (49 degrees C, 20% rh), and hot-wet (35 degrees C, 79% rh) environments while subjects were hypo- or euhydrated. Six male and six female subjects, matched for maximal aerobic power and percent body fat, completed two exercise tests in each environment both before and after a 10-day heat acclimation program. One exercise test was completed during euhydration and one during hypohydration (-5.0% from baseline body weight). In general, no significant (P greater than 0.05) differences were noted between men and women at the completion of exercise for rectal temperature (Tre), mean skin temperature (Tsk), or heat rate (HR) during any of the experimental conditions. Hypohydration generally increased Tre and HR values and decreased sweat rate values while not altering Tsk values. In the hypohydration experiments, heat acclimation significantly reduced Tre (0.19 degrees C) and HR (13 beats X min-1) values in the comfortable environment, but only HR values were reduced in hot-dry (21 beats X min-1) and hot-wet (21 beats X min-1) environments. The present findings indicated that men and women respond in a physiologically similar manner to hypohydration during exercise. They also indicated that for hypohydrated subjects heat acclimation decreased thermoregulatory and cardiovascular strain in a comfortable environment, but only cardiovascular strain decreased in hot environments.

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