Metabolic, Cardiac, and Hemorheological Responses to Submaximal Exercise under Light and Moderate Hypobaric Hypoxia in Healthy Men

We compared the effects of metabolic, cardiac, and hemorheological responses to submaximal exercise under light hypoxia (LH) and moderate hypoxia (MH) versus normoxia (N). Ten healthy men (aged 21.3 ± 1.0 years) completed 30 min submaximal exercise corresponding to 60% maximal oxygen uptake at normoxia on a cycle ergometer under normoxia (760 mmHg), light hypoxia (596 mmHg, simulated 2000 m altitude), and moderate hypoxia (526 mmHg, simulated 3000 m altitude) after a 30 min exposure in the respective environments on different days, in a random order. Metabolic parameters (oxygen saturation (SPO2), minute ventilation, oxygen uptake, carbon dioxide excretion, respiratory exchange ratio, and blood lactate), cardiac function (heart rate (HR), stroke volume, cardiac output, and ejection fraction), and hemorheological properties (erythrocyte deformability and aggregation) were measured at rest and 5, 10, 15, and 30 min after exercise. SPO2 significantly reduced as hypoxia became more severe (MH > LH > N), and blood lactate was significantly higher in the MH than in the LH and N groups. HR significantly increased in the MH and LH groups compared to the N group. There was no significant difference in hemorheological properties, including erythrocyte deformability and aggregation. Thus, submaximal exercise under light/moderate hypoxia induced greater metabolic and cardiac responses but did not affect hemorheological properties.

Download Full-text

Relationship between ventilatory response and body temperature during prolonged submaximal exercise

Journal of Applied Physiology ◽

10.1152/japplphysiol.00541.2005 ◽

2006 ◽

Vol 100 (2) ◽

pp. 414-420 ◽

Cited By ~ 57

Author(s):

Keiji Hayashi ◽

Yasushi Honda ◽

Takeshi Ogawa ◽

Narihiko Kondo ◽

Takeshi Nishiyasu

Keyword(s):

Body Temperature ◽

Oxygen Uptake ◽

Skin Temperature ◽

Blood Lactate ◽

Core Temperature ◽

Core Body Temperature ◽

Minute Ventilation ◽

Submaximal Exercise ◽

Rate Of Increase ◽

The Relationship

We examined whether an increase in skin temperature or the rate of increase in core body temperature influences the relationship between minute ventilation (V̇e) and core temperature during prolonged exercise in the heat. Thirteen subjects exercised for 60 min on a cycle ergometer at 50% of peak oxygen uptake while wearing a suit perfused with water at 10°C (T10), 35°C (T35), or 45°C (T45). During the exercise, esophageal temperature (Tes), skin temperature, heart rate (HR), V̇e, tidal volume, respiratory frequency (f), respiratory gases, blood pressure (BP), and blood lactate were all measured. We found that oxygen uptake, carbon dioxide output, BP, and blood lactate did not differ among the sessions. Tes, HR, V̇e, and f remained nearly constant from minute 10 onward in the T10 session, but all of these parameters progressively increased in the T35 and T45 sessions, and significantly higher levels were seen in the T45 than the T35 session. For all but two subjects in the T35 and T45 sessions, plotting V̇e as a function of Tes revealed no threshold for hyperventilation; instead, increases in V̇e were linearly related to Tes, and there were no significant differences in the slopes or intercepts between the T35 and T45 sessions. Thus, during prolonged submaximal exercise in the heat, V̇e increases with core temperature, and the influences of skin temperature and the rate of increase in Tes on the relationship between V̇e and Tes are apparently small.

Download Full-text

The Cycling Physiology of Miguel Indurain 14 Years After Retirement

International Journal of Sports Physiology and Performance ◽

10.1123/ijspp.7.4.397 ◽

2012 ◽

Vol 7 (4) ◽

pp. 397-400 ◽

Cited By ~ 7

Author(s):

Iñigo Mujika

Keyword(s):

Oxygen Uptake ◽

Blood Lactate ◽

Body Mass ◽

Power Output ◽

Aerobic Power ◽

Cycle Ergometer ◽

Cycle Ergometer Test ◽

Age Related ◽

The Individual ◽

Aerobic Power Output

Age-related fitness declines in athletes can be due to both aging and detraining. Very little is known about the physiological and performance decline of professional cyclists after retirement from competition. To gain some insight into the aging and detraining process of elite cyclists, 5-time Tour de France winner and Olympic Champion Miguel Indurain performed a progressive cycle-ergometer test to exhaustion 14 y after retirement from professional cycling (age 46 y, body mass 92.2 kg). His maximal values were oxygen uptake 5.29 L/min (57.4 mL · kg−1 · min−1), aerobic power output 450 W (4.88 W/kg), heart rate 191 beats/min, blood lactate 11.2 mM. Values at the individual lactate threshold (ILT): 4.28 L/min (46.4 mL · kg−1 · min−1), 329 W (3.57 W/kg), 159 beats/min, 2.4 mM. Values at the 4-mM onset of blood lactate accumulation (OBLA): 4.68 L/min (50.8 mL · kg−1 · min−1), 369 W (4.00 W/kg), 170 beats/min. Average cycling gross efficiency between 100 and 350 W was 20.1%, with a peak value of 22.3% at 350 W. Delta efficiency was 27.04%. Absolute maximal oxygen uptake and aerobic power output declined by 12.4% and 15.2% per decade, whereas power output at ILT and OBLA declined by 19.8% and 19.2%. Larger declines in maximal and submaximal values relative to body mass (19.4–26.1%) indicate that body composition changed more than aerobic characteristics. Nevertheless, Indurain’s absolute maximal and submaximal oxygen uptake and power output still compare favorably with those exhibited by active professional cyclists.

Download Full-text

Nutritional status affects branched-chain oxoacid dehydrogenase activity during exercise in humans

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1997.272.2.e233 ◽

1997 ◽

Vol 272 (2) ◽

pp. E233-E238 ◽

Cited By ~ 7

Author(s):

M. L. Jackman ◽

M. J. Gibala ◽

E. Hultman ◽

T. E. Graham

Keyword(s):

Amino Acid ◽

Oxygen Uptake ◽

Muscle Glycogen ◽

Random Order ◽

Submaximal Exercise ◽

The Other ◽

Branched Chain Amino Acid ◽

Low Carbohydrate ◽

Branched Chain ◽

Exercise In Humans

We examined the effect of glycogen availability and branched-chain amino acid (BCAA) supplementation on branched-chain oxoacid dehydrogenase (BCOAD) activity during exercise. Six subjects cycled at approximately 75% of their maximal oxygen uptake to exhaustion on three occasions under different preexercise conditions: 1) low muscle glycogen (LOW), 2) low muscle glycogen plus BCAA supplementation (LOW+BCAA), and 3) high muscle glycogen (CON). The LOW trial was performed first, followed by the other two conditions in random order, and biopsies for all trials were obtained at rest, after 15 min of exercise (15 min), and at the point of exhaustion during the LOW trial (49 min). BCOAD activity was not different among the three conditions at rest; however, at 15 min BCOAD activity was higher (P < or = 0.05) for the LOW (31 +/- 5%) and LOW+BCAA (43 +/- 11%) conditions compared with CON (12 +/- 1%). BCOAD activity at 49 min was not different from respective values at 15 min for any condition. These data indicate that BCOAD is rapidly activated during submaximal exercise under conditions associated with low carbohydrate availability. However, there was no relationship between BCOAD activity and glycogen concentration or net glycogenolysis, which suggests that factors other than glycogen availability are important for BCOAD regulation during exercise in humans.

Download Full-text

Effect of graded epinephrine infusion on blood lactate response to exercise

Journal of Applied Physiology ◽

10.1152/jappl.1995.79.4.1206 ◽

1995 ◽

Vol 79 (4) ◽

pp. 1206-1211 ◽

Cited By ~ 11

Author(s):

M. J. Turner ◽

E. T. Howley ◽

H. Tanaka ◽

M. Ashraf ◽

D. R. Bassett ◽

...

Keyword(s):

Oxygen Uptake ◽

Blood Lactate ◽

Random Order ◽

Peak Oxygen Uptake ◽

Sudden Increase ◽

Control Test ◽

Epinephrine Infusion ◽

Exercise Tests ◽

Ergometer Exercise ◽

Graded Exercise

In an attempt to determine whether the lactate threshold (LT) is the result of a sudden increase in plasma epinephrine (Epi), eight healthy college-aged males (22.4 +/- 0.4 yr) were recruited to perform three cycle ergometer exercise tests. Each subject performed a graded exercise test (GXT) to determine LT, Epi threshold, and norepinephrine threshold (64.6 +/- 2.4, 62.5 +/- 2.4, and 60.8 +/- 4.3% peak oxygen uptake, respectively). Each subject also completed, in random order, two 30-min submaximal (20% peak oxygen uptake below LT) exercise tests. During one test, graded Epi infusions were carried out at rates of 0.02–0.12 micrograms.kg-1.min-1; the other served as a control test. Infusion resulted in plasma Epi concentrations similar to those observed during GXT. The increase in blood lactate with Epi infusion was significantly greater than that during the control test (3.0 +/- 0.3 vs. 1.4 +/- 0.1 mmol/l at minute 30) but did not approach levels exhibited during GXT. We suggest an interaction of the increasing plasma Epi with other factors may be responsible for the sudden increase in blood lactate during graded exercise.

Download Full-text

Acetazolamide alters temperature regulation during submaximal exercise

Journal of Applied Physiology ◽

10.1152/jappl.1990.69.4.1402 ◽

1990 ◽

Vol 69 (4) ◽

pp. 1402-1407 ◽

Cited By ~ 14

Author(s):

W. F. Brechue ◽

J. M. Stager

Keyword(s):

Stroke Volume ◽

Minute Ventilation ◽

Exercise Bout ◽

Cycle Ergometer ◽

Submaximal Exercise ◽

Whole Body ◽

Co2 Removal ◽

O2 Uptake ◽

Double Blind ◽

Hypoxic Conditions

Acetazolamide (ACZ), a potent carbonic anhydrase inhibitor, is known to decrease submaximal exercise tolerance under normoxic and hypoxic conditions. These decrements in performance occur despite the maintenance of O2 consumption and CO2 removal. Because ACZ is a diuretic, it induces a moderate hypohydration that may have a role in reducing the ability to sustain exercise through cardiovascular and thermoregulatory impairment. To investigate this potential impairment, seven healthy males between 21 and 35 yr of age were studied in a double-blind crossover design (placebo vs. ACZ). ACZ was administered in three 250-mg oral doses 14, 8, and 2 h before exercise. Subjects exercised at 70% peak O2 uptake for 30 min on a cycle ergometer in a normoxic thermoneutral environment (25 degrees C, 40% relative humidity). Results indicate that exercise minute ventilation was greater but O2 uptake, CO2 output, and respiratory exchange ratio did not differ with ACZ. ACZ led to lower mean skin (0.7 degrees C), higher rectal (0.6 degrees C), and higher mean body temperatures (0.4 degrees C) after 30 min of exercise. Whole-body sweat loss was reduced 23%, and heat storage during the exercise bout was increased 55%. Stroke volume decreased 25%, and arteriovenous O2 difference increased 15%. A significant inverse relationship (r = -0.63) between heart rate and stroke volume was observed. It is concluded that previously reported decreases in the ability to sustain submaximal exercise with ACZ may be related to hypohydration-induced impairment of the cardiovascular and thermoregulatory systems.

Download Full-text

Growth hormone responses to 3 different exercise bouts in 18- to 25- and 40- to 50-year-old men

Applied Physiology Nutrition and Metabolism ◽

10.1139/h08-034 ◽

2008 ◽

Vol 33 (4) ◽

pp. 706-712 ◽

Cited By ~ 13

Author(s):

Kate L. Gilbert ◽

Keith A. Stokes ◽

George M. Hall ◽

Dylan Thompson

Keyword(s):

Growth Hormone ◽

Resistance Exercise ◽

Blood Lactate ◽

Maximal Oxygen Consumption ◽

Exercise Bout ◽

Random Order ◽

Young Group ◽

Cycle Ergometer ◽

Middle Aged ◽

Time Curve

Exercise is a potent stimulus for growth hormone (GH) release, although aging appears to attenuate this response. The aim of this study was to investigate GH responses to different exercise stimuli in young and early middle-aged men. Eight men aged 18–25 y and 8 men aged 40–50 y completed 3 trials, at least 7 days apart, in a random order: 30 s cycle-ergometer sprint (sprint), 30 min resistance exercise bout (resistance), 30 min cycle at 70% maximal oxygen consumption (endurance). Blood samples were taken pre-, during, and post-exercise, and area under the GH vs. time curve was calculated for a total of 120 min. Mean blood lactate concentrations and percentage heart rate maximum at which the participants were working were not different between groups in any of the trials. In both groups, blood lactate concentrations were significantly lower in the endurance trial than in the sprint and resistance trials. There were no significant differences in resting GH concentration between groups or trials. GH AUC was significantly greater in the young group than the early middle-aged group, in both sprint (531 (±347) vs. 81 (±54) µg·L–1 per 120 min, p = 0.003) and endurance trials (842 (±616) vs. 177 (±137) µg·L–1 per 120 min, p = 0.010). Endurance exercise elicits a greater GH response than sprint and resistance exercise; however, aging per se, factors associated with aging, or an inability to achieve a sufficient absolute exercise intensity results in a smaller GH response to an exercise stimulus in early middle-aged men.

Download Full-text

Influence of menstrual phase on ventilatory response to submaximal exercise

South African Journal of Sports Medicine ◽

10.17159/2413-3108/2006/v18i2a241 ◽

2009 ◽

Vol 18 (2) ◽

pp. 31 ◽

Cited By ~ 2

Author(s):

T Oosthuiyse ◽

AN Bosch

Keyword(s):

Sports Medicine ◽

Ventilatory Response ◽

Minute Ventilation ◽

Submaximal Exercise ◽

Respiratory Drive ◽

Ovarian Hormone ◽

Menstrual Phase ◽

Ventilatory Parameters ◽

Significant Difference ◽

The Difference

Objectives. To determine whether an increase in respiratory drive, due to elevated progesterone and oestrogen concentration during various menstrual phases, persists throughout prolonged submaximal exercise and potentially contributes to fatigue. Furthermore, to determine whether the difference in the ventilatory response to exercise from one menstrual phase to another is correlated to the ovarian hormone concentrations. Design. We compared the change in ventilatory parameters during 90 min exercise at 60%VO2max between the early follicular (EF) and mid-luteal (ML) phase (N = 9) and between the EF and late follicular (LF) phase (N = 5) in eumenorrhoeic women. Main outcome measures. Menstrual phase comparisons and correlations between the change in ventilatory parameters (minute ventilation (VE), respiratory rate (RR), tidal volume) from the EF to ML or from the EF to LF phase and ovarian hormone concentration. Results. The difference in RR between EF and ML phases correlated to progesterone concentration in the ML phase (r = 0.7, p = 0.04). In addition, RR was higher during exercise in the ML compared with EF phase for the full duration of exercise by on average 2.3 ± 2.1 breaths/min (p < 0.05). However, no difference in submaximal VO2 between menstrual phases was evident. No significant difference in exercising-VE was observed between menstrual phases, but the change in VE from EF to ML correlated to oestrogen (r = 0.8, p = 0.02) and progesterone (r = 0.7, p = 0.04) concentration in the ML phase. South African Journal of Sports Medicine Vol. 18 (2) 2006: pp. 31-37

Download Full-text

Modification of Cooper’s 12-min Run Test to Predict Maximum Oxygen Uptake in Indian Cricketers

International Journal of Physical Education Fitness and Sports ◽

10.34256/ijpefs2029 ◽

2020 ◽

Vol 9 (2) ◽

pp. 72-78

Author(s):

Amit Bandyopadhyay

Keyword(s):

Oxygen Uptake ◽

Study Groups ◽

Cycle Ergometer ◽

Gas Analysis ◽

Maximum Oxygen Uptake ◽

Regression Equations ◽

Female Cricket ◽

Significant Difference ◽

Ergometer Exercise ◽

Run Test

Cooper’s 12-minute run test (CRT) for prediction of maximum oxygen uptake (VO2max) has not yet been explored in Indian sportspersons. Present investigation was conducted to evaluate the applicability of CRT in Indian cricketers. 75 male and 45 female cricket players were randomly recruited from reputed cricket academies of Kolkata, India and were randomly assigned into the study group (male = 45, female = 25) and confirmatory group (male = 30, female = 20). Incremental cycle ergometer exercise was used for direct estimation of VO2max by expired gas analysis and the indirect prediction of VO2max (PVO2max) was performed by CRT method. The current protocol of CRT was found to be inapplicable in both the genders of Cricketers due to a significant difference between PVO2max and VO2max and a large limit of agreement between PVO2max and VO2max in the study groups. A significant correlation (r = 0.76 in males and r = 0.79 in females, p<0.001) was depicted between VO2max and distance covered in CRT. Regression equations were computed based on the significant correlation. The application of these equations in the confirmatory groups revealed an insignificant difference between PVO2max and VO2max and narrow limits of agreement. Standard errors of the estimate of the regression norms were also minimal. Therefore, modified equations are recommended for CRT application for valid and precise evaluation of cardiorespiratory fitness in terms of VO2max in male and female Indian cricketers.

Download Full-text

Effect of acute submaximal physical exercise before decompression dive on tumor necrosis factor alpha concentration among male trained divers

International Journal of Public Health Science (IJPHS) ◽

10.11591/ijphs.v10i2.20666 ◽

2021 ◽

Vol 10 (2) ◽

pp. 289

Author(s):

Chikih Chikih ◽

Guritno Suryokusumo ◽

Astrid Sulistomo

Keyword(s):

Treatment Group ◽

Tumor Necrosis ◽

Decompression Sickness ◽

Cycle Ergometer ◽

Submaximal Exercise ◽

Control Group ◽

Necrosis Factor Alpha ◽

Significant Difference ◽

Quasi Experimental ◽

And Control

The increase of inflammatory biomarkers due to decompression dive is one of the factors that could cause decompression sickness (DCS), one of them is tumor necrosis alpha (TNFα). According to the preconditioning theory, exercise before dive can reduce amount of gas bubble to prevent DCS. This study aimed to prove that exercise before diving can prevent increase of TNFα. This study employed quasi-experimental design with trained male divers. The subject divided into two groups, treatment and control. The treatment group got submaximal exercise with 70% heart rate intensity, using cycle ergometer with young men's Christian association (YMCA) procedure modify by Guritno, 24 hours before decompression dive 280 kPa bottom time 80 minute with US-NAVY table, whereas the control group only do decompression dive. TNFα expression was checked three times, at beginning of study, before dive and after dive. In treatment group there was insignificant decrease TNFα, from 7.06±1.85pg./ml to 6.75±1.81pg./ml, whereas the control group showed a significant increased TNFα, from 8.22 (1.45 to 13.11)pg./ml to 8.39 (1.73 to 12.18)pg/ml, and significant difference was found between the mean difference for two groups p<0.05. It can be concluded that acute submaximal exercise prevents an increase of TNFα after single dive decompression to prevent possibility occurring DCS).

Download Full-text