The Respiration of Cancer Pagurus Under Normoxic and Hypoxic Conditions

1982 ◽  
Vol 97 (1) ◽  
pp. 273-288 ◽  
Author(s):  
S. M. BRADFORD ◽  
A. C. TAYLOR
Keyword(s):  
Oxygen Consumption ◽  
Energy Savings ◽  
Lactate Concentration ◽  
Oxygen Affinity ◽  
Cardiac Activity ◽  
Blood Lactate Concentration ◽  
Minor Role ◽  
Rhythmic Pattern ◽  
Cancer Pagurus ◽  
Wide Range

The respiration of Cancer pagurus under normoxic conditions and its respiratory responses to hypoxia are described. Respiration of quiescent crabs is characterized by a rhythmic pattern of ventilation and cardiac activity in which periods of apnoea and bradycardia of approximately 5 min duration alternate with longer periods of active ventilation and cardiac activity. The significance of this rhythmic ventilatory behaviour is discussed and evidence is presented to account for this behaviour in terms of allowing energy savings to be made during periods of inactivity. During a ventilatory pause the PO2 of the post-branchial blood falls from its normal level of 94 ± 5 torr to only 24 ± 3 torr. The blood of Cancer provides a store of oxygen which is used during pausing to maintain aerobic metabolism. Anaerobic metabolism does not appear to contribute significantly to energy production during these periods since no increase in the blood lactate concentration was recorded. Cancer haemocyanin has a high oxygen affinity (P50 = 5–10 torr) and exhibits a large, positive Bohr shift (Δ log P50/pH = −1.18). However, under normal conditions the pigment has only a minor role in supplying oxygen to the tissues, since over 91% is carried in solution. Cancer pagurus exhibits quite a high degree of respiratory independence and is able to maintain its rate of oxygen consumption approximately constant over a wide range of ambient oxygen tension, down to a PO2 of 60–80 torr, below which it declines. Similarly there was little change in heart rate during hypoxia until a PO2 of 20–40 torr was reached below which it also declined sharply. Oxygen consumption during hypoxia was maintained primarily as a result of an increase in ventilation volume and oxygen extraction. During hypoxia the PO2 of both the pre- and post-branchial blood declined and resulted in a reduction in the PO2 gradient across the respiratory surface (ΔPO2). Oxygen uptake during hypoxia was facilitated, however, by an increase in the transfer factor (TO2).

scholarly journals Effects of a 2-km Swim on Markers of Cycling Performance in Elite Age-Group Triathletes

Sports ◽  
2019 ◽  
Vol 7 (4) ◽  
pp. 82
Author(s):  
Jeffrey Rothschild ◽  
George H. Crocker
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Blood Lactate ◽  
Peak Power ◽  
Maximal Oxygen Consumption ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Cycling Performance ◽  
Age Group

The purpose of this study was to examine the effects of a 2-km swim on markers of subsequent cycling performance in well-trained, age-group triathletes. Fifteen participants (10 males, five females, 38.3 ± 8.4 years) performed two progressive cycling tests between two and ten days apart, one of which was immediately following a 2-km swim (33.7 ± 4.1 min). Cycling power at 4-mM blood lactate concentration decreased after swimming by an average of 3.8% (p = 0.03, 95% CI −7.7, 0.2%), while heart rate during submaximal cycling (220 W for males, 150 W for females) increased by an average of 4.0% (p = 0.02, 95% CI 1.7, 9.7%), compared to cycling without prior swimming. Maximal oxygen consumption decreased by an average of 4.0% (p = 0.01, 95% CI −6.5, −1.4%), and peak power decreased by an average of 4.5% (p < 0.01, 95% CI −7.3, −2.3%) after swimming, compared to cycling without prior swimming. Results from this study suggest that markers of submaximal and maximal cycling are impaired following a 2-km swim.

scholarly journals Prolonged static stretching causes acute, nonmetabolic fatigue and impairs exercise tolerance during severe-intensity cycling

2020 ◽  
Vol 45 (8) ◽  
pp. 902-910
Author(s):  
Alessandro L. Colosio ◽  
Massimo Teso ◽  
Silvia Pogliaghi
Keyword(s):  
Oxygen Consumption ◽  
Exercise Tolerance ◽  
Muscle Activation ◽  
Metabolic Response ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time To Exhaustion ◽  
Static Stretching ◽  
Perception Of Effort ◽  
Severe Intensity

We tested the hypothesis that static stretching, an acute, nonmetabolic fatiguing intervention, reduces exercise tolerance by increasing muscle activation and affecting muscle bioenergetics during cycling in the “severe” intensity domain. Ten active men (age, 24 ± 2 years; body mass, 74 ± 11 kg; height, 176 ± 8 cm) participated in identical constant-load cycling tests of equal intensity, of which 2 tests were carried out under control conditions and 2 were done after stretching. This resulted in a 5% reduction of maximal isokinetic sprinting power output. We measured (i) oxygen consumption, (ii) electromyography, (iii) deoxyhemoglobin, (iv) blood lactate concentration; (v) time to exhaustion, and (vi) perception of effort. Finally, oxygen consumption and deoxyhemoglobin kinetics were determined. Force reduction following stretching was accompanied by augmented muscle excitation at a given workload (p = 0.025) and a significant reduction in time to exhaustion (p = 0.002). The time to peak oxygen consumption was reduced by stretching (p = 0.034), suggesting an influence of the increased muscle excitation on the oxygen consumption kinetics. Moreover, stretching was associated with a mismatch between O2 delivery and utilization during the isokinetic exercise, increased perception of effort, and blood lactate concentration; these observations are all consistent with an increased contribution of the glycolytic energy system to sustain the same absolute intensity. These results suggest a link between exercise intolerance and the decreased ability to produce force. Novelty We provided the first characterization of the effects of prolonged stretching on the metabolic response during severe cycling. Stretching reduced maximal force and augmented muscle activation, which in turn increased the metabolic response to sustain exercise.

The Effect of Aging on the Lactate Threshold in Untrained Men

1997 ◽  
Vol 5 (1) ◽  
pp. 39-49 ◽  
Author(s):  
K. Fiona Iredale ◽  
Myra A. Nimmo
Keyword(s):  
Oxygen Consumption ◽  
Correlation Coefficient ◽  
Blood Lactate ◽  
Lactate Threshold ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Peak Oxygen Consumption ◽  
Reserve Capacity ◽  
The Difference ◽  
Treadmill Protocol

Thirty-three men (age 26–55 years) who did not exercise regularly were exercised to exhaustion using an incremental treadmill protocol. Blood lactate concentration was measured to identify lactate threshold (LT, oxygen consumption at which blood lactate concentration begins to systematically increase). The correlation coefficient for LT (ml · kg−1 · min−1) with age was not significant, but when LT was expressed as a percentage of peak oxygen consumption (VO2 peak), the correlation was r = +.69 (p < .01). This was despite a lack of significant correlation between age and VO2 peak (r = −.33). The correlation between reserve capacity (the difference between VO2 peak and LT) and age was r = −.73 (p < .01 ), and reserve capacity decreased at a rate of 3.1 ml · kg−1 · min−1 per decade. It was concluded that the percentage of VO2 peak at which LT occurs increases progressively with age, with a resultant decrease in reserve capacity.

Determination of maximal oxygen consumption in exercising pregnant sheep

1992 ◽  
Vol 73 (1) ◽  
pp. 234-239 ◽  
Author(s):  
M. T. Jones ◽  
R. E. Rawson ◽  
D. Robertshaw
Keyword(s):  
Oxygen Consumption ◽  
Maximal Oxygen Consumption ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Flow Distribution ◽  
Pregnant Sheep ◽  
Flow Through ◽  
The Relationship ◽  
Exercise During Pregnancy

Previous work with pregnant ewes has shown that acute bouts of exercise may cause changes in plasma hormone concentrations, blood flow distribution, and maternal and fetal temperatures. However, most of these studies do not quantify the chosen exercise intensity through measurement of oxygen consumption (VO2). Therefore the purpose of this study was to statistically model the VO2 response of pregnant sheep to treadmill (TM) exercise to determine the exercise intensities (% maximal VO2) of previous studies. Ewes with either single (n = 9) or twin (n = 5) fetuses were studied from 100 to 130 days of gestation. After 1–2 wk of TM habituation, maximal VO2 (VO2max) was determined by measurements of VO2 (open flow-through method) and blood lactate concentration. VO2 was measured as a function of TM incline (0, 3, 5, and 7 degree) and speed (0.8–3.4 m/s). VO2max averaged 57 +/- 7 (SD) ml.min-1.kg-1, and peak lactate concentration during exercise averaged 22 +/- 2 mmol/l. The relationship between VO2 (ml.min-1.kg-1) and incline (INC) and speed (SP) [VO2 = 0.70(INC) + 13.95(SP) + 1.07(INC x SP) - 1.18] was linear (r2 = 0.94). Our findings suggest that most previous research used exercise intensities less than 60% VO2max and indicate the need for further research that examines the effect of exercise during pregnancy at levels greater than 60% VO2max.

scholarly journals Assessment of Maximal Aerobic Capacity in Ski Mountaineering: A Laboratory-Based Study

2021 ◽  
Vol 18 (13) ◽  
pp. 7002
Author(s):  
Verena Menz ◽  
Martin Niedermeier ◽  
Rainer Stehle ◽  
Hendrik Mugele ◽  
Martin Faulhaber
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Mean Difference ◽  
Maximum Oxygen Consumption ◽  
Maximum Heart Rate ◽  
Maximal Aerobic Capacity ◽  
Specific Test ◽  
Good Agreement

This study aims to evaluate the agreement in maximum oxygen consumption (V˙O2max) between a running protocol and a ski mountaineering (SKIMO) protocol. Eighteen (eleven males, seven females) ski mountaineers (age: 25 ± 3 years) participated in the study. V˙O2max, maximum heart rate (HRmax), and maximum blood lactate concentration (BLAmax) were determined in an incremental uphill running test and an incremental SKIMO-equipment-specific test. V˙O2max did not differ between the SKIMO and uphill running protocols (p = 0.927; mean difference –0.07 ± 3.3 mL/min/kg), nor did HRmax (p = 0.587, mean difference –0.7 ± 5.1 bpm). A significant correlation was found between V˙O2max SKIMO and V˙O2max running (p ≤ 0.001; ICC = 0.862 (95% CI: 0.670−0.946)). The coefficient of variation was 4.4% (95% CI: 3.3−6.5). BLAmax was significantly lower for SKIMO compared to running (12.0 ± 14.1%; p = 0.002). This study demonstrates that V˙O2max determined with a traditional uphill running protocol demonstrates good agreement with an equipment-specific SKIMO protocol.

Reduced Fatigue in Passive Versus Active Recovery: An Examination of Repeated-Change-of-Direction Sprints in Basketball Players

2018 ◽  
Vol 13 (8) ◽  
pp. 1034-1041
Author(s):  
Maria C. Madueno ◽  
Vincent J. Dalbo ◽  
Joshua H. Guy ◽  
Kate E. Giamarelos ◽  
Tania Spiteri ◽  
...  
Keyword(s):  
Heart Rate ◽  
Oxygen Consumption ◽  
Perceived Exertion ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Rating Of Perceived Exertion ◽  
Active Recovery ◽  
Basketball Players ◽  
Change Of Direction ◽  
Passive Recovery

Purpose: To investigate the physiological and performance effects of active and passive recovery between repeated-change-of-direction sprints. Methods: Eight semiprofessional basketball players (age: 19.9 [1.5] y; stature: 183.0 [9.6] cm; body mass: 77.7 [16.9] kg; body fat: 11.8% [6.3%]; and peak oxygen consumption: 46.1 [7.6] mL·kg−1·min−1) completed 12 × 20-m repeated-change-of-direction sprints (Agility 5-0-5 tests) interspersed with 20 seconds of active (50% maximal aerobic speed) or passive recovery in a randomized crossover design. Physiological and perceptual measures included heart rate, oxygen consumption, blood lactate concentration, and rating of perceived exertion. Change-of-direction speed was measured during each sprint using the change-of-direction deficit (CODD), with summed CODD time and CODD decrement calculated as performance measures. Results: Average heart rate (7.3 [6.4] beats·min−1; P = .010; effect size (ES) = 1.09; very likely) and oxygen consumption (4.4 [5.0] mL·kg−1·min−1; P = .12; ES = 0.77; unclear) were moderately greater with active recovery compared with passive recovery across sprints. Summed CODD time (0.87 [1.01] s; P = .07; ES = 0.76, moderate; likely) and CODD decrement (8.1% [3.7%]; P < .01; ES = 1.94, large; almost certainly) were higher with active compared with passive recovery. Trivial–small differences were evident for rating of perceived exertion (P = .516; ES = 0.19; unclear) and posttest blood lactate concentration (P = .29; ES = 0.40; unclear) between recovery modes. Conclusions: Passive recovery between repeated-change-of-direction sprints may reduce the physiological stress and fatigue encountered compared with active recovery in basketball players.

scholarly journals Acute Physiological Responses to High-Intensity Resistance Circuit Training vs. Traditional Strength Training in Soccer Players

Biology ◽  
2020 ◽  
Vol 9 (11) ◽  
pp. 383
Author(s):  
Cristian Marín-Pagán ◽  
Anthony J. Blazevich ◽  
Linda H. Chung ◽  
Salvador Romero-Arenas ◽  
Tomás T. Freitas ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
High Intensity ◽  
Maximal Oxygen Consumption ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Soccer Players ◽  
Metabolic Responses ◽  
Post Exercise ◽  
Training Strategy ◽  
Training Protocols

The aim of this study was to evaluate and compare the cardiorespiratory and metabolic responses induced by high-intensity resistance circuit-based (HRC) and traditional strength (TS) training protocols. Ten amateur soccer players reported to the laboratory on four occasions: (1) protocol familiarization and load determination; (2) maximal oxygen consumption test; (3) and (4) resistance training protocols (HRC and TS), completed in a cross-over randomized order. In both protocols, the same structure was used (two blocks of 3 sets × 3 exercises, separated by a 5-min rest), with only the time between consecutive exercises differing: TS (3 min) and HRC (~35 s, allowing 3 min of local recovery). To test for between-protocol differences, paired t-tests were applied. Results showed that oxygen consumption and heart rate during HRC were 75% and 39% higher than TS, respectively (p < 0.001). After the training sessions, blood lactate concentration at 1.5, 5 and 7 min and excess post-exercise oxygen consumption were higher in HRC. The respiratory exchange ratio was 6.7% greater during HRC, with no between-group differences found post-exercise. The energy cost of HRC was ~66% higher than TS. In conclusion, HRC training induces greater cardiorespiratory and metabolic responses in soccer players and thus may be a time-effective training strategy.

Cholinergic and opioid involvement in release of growth hormone during exercise and recovery

1993 ◽  
Vol 75 (2) ◽  
pp. 870-878 ◽  
Author(s):  
D. L. Thompson ◽  
J. Y. Weltman ◽  
A. D. Rogol ◽  
D. L. Metzger ◽  
J. D. Veldhuis ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Oxygen Consumption ◽  
Blood Lactate ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Exercise Bout ◽  
Peak Oxygen Consumption ◽  
Moderate Intensity ◽  
Moderate Intensity Exercise ◽  
Testing Period

Cholinergic and opioid pathways have been implicated as mediators of the increased growth hormone (GH) release observed during exercise. This study compared the GH responses induced by a moderate-intensity exercise bout during treatment with placebo (Plac), the opioid receptor antagonist naltrexone (Nalt), the indirect cholinergic agonist pyridostigmine (PD), or a combination of the two drugs (P + N). Ten active males served as subjects (age, 25.1 +/- 0.6 yr; wt, 79.7 +/- 2.5 kg; % body fat, 14.9 +/- 1.4; peak oxygen consumption, 46.2 +/- 2.7 ml.kg-1 x min-1). Blood samples were drawn at 5-min intervals during the 4.5-h testing period to determine the GH concentration. The testing period was divided as follows: 0600–700 h = baseline, 0700–0800 h = preexercise, 0800–0830 h = exercise, and 0830–1030 h = recovery. Drugs were administered 1 h before exercise (at 0700 h). Exercise consisted of 30 min of cycling at an individualized work load previously found to elicit a blood lactate concentration of 2.5 mM. Heart rate, oxygen consumption, blood lactate, and blood glucose were measured throughout the exercise period. Results indicated that neither the resting GH concentration nor the metabolic parameters during exercise were altered by the treatments. Peak serum GH concentration was not significantly altered by the treatments (range 7.3 +/- 2.0 to 12.6 +/- 4.4 micrograms/l).(ABSTRACT TRUNCATED AT 250 WORDS)

Relative aerobic and anaerobic energy contribution in race fit endurance and Thoroughbred racehorses during strenuous exercise

2019 ◽  
Vol 15 (5) ◽  
pp. 299-306
Author(s):  
R. Léguillette ◽  
P. Greco-Otto ◽  
R. Sides ◽  
S.L. Bond ◽  
S. El Alami ◽  
...  
Keyword(s):  
Oxygen Consumption ◽  
Minute Ventilation ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Strenuous Exercise ◽  
Energy Contribution ◽  
Maximal Intensity ◽  
Thoroughbred Racehorses ◽  
Calculated Parameter ◽  
High Level

The objective was to compare fit Arabian endurance and Thoroughbred racehorses’ responses to a maximal intensity standardised incremental treadmill test (MaxSIT) with respect to: (1) their relative aerobic contributions during maximal exercise; and (2) selected physiological parameters related to performance. Six high-level endurance Arabians and six race-ready Thoroughbreds performed a MaxSIT starting at 8 m/s and increasing by 1 m/s increments 60 s until maximum oxygen consumption (V̇O2max) was reached. Heart rate (HR), blood lactate concentration (BLac), haematocrit (Hct), minute ventilation (V̇E) and oxygen consumption (V̇O2) were measured. V̇O2max, the speeds at which the HR were 200 and 160 bpm, respectively (V200, V160), the speed at which the BLac reached 4 mmol/l (VLa4) and lactate at HR200 (BLa200) were calculated. The relative aerobic energy input was determined using ΔBLacPeak-Resting increase as previously described. Data were expressed as median with interquartile range and analysed with a Wilcoxon rank sum test (P<0.05). Endurance horses had greater V̇O2max (202.5 ml/(kg.min) (190.3-211) vs 152.7 ml/(kg.min) (140.5-158.3); P<0.001) and had a greater aerobic energy contribution to total exercise effort (89.9% (87.0-96) vs 82.8% (81.1-84.1); P=0.009) than Thoroughbreds. Endurance horses reached HR>200 bpm on the treadmill, but had a lower HRmax (210 bpm (205-217) vs 226 bpm (219-228); P=0.008), BLa200 (3.8 mmol/l (2.7-5.5) vs 4.8 mmol/l (3.6-5.2); P<0.001) and Hctmax (56.4% (54.9-57.5) vs 61.5% (59-64); P=0.002). Endurance horses median VLa4 was 11.6 m/s (11.0-13.0); V200=11.9 m/s (10.9-12.3) and V160=8.5 m/s (7.2-8.6). Because of the HR and speed characteristics of modern endurance races, we proposed BLa200 as a new calculated parameter with which to assess endurance horses. Trained endurance horses accumulate less lactate, have a greater V̇O2max and relative aerobic contribution to their energy requirements at maximal intensity exercise despite a lower blood haematocrit.

High doses of sodium nitrate prior to exhaustive exercise increases plasma peroxynitrite levels in well-trained subjects: randomized, double-blinded, crossover study

2019 ◽  
Vol 44 (12) ◽  
pp. 1305-1310 ◽  
Author(s):  
Farhad Gholami ◽  
Leila Rahmani ◽  
Fatemeh Amirnezhad ◽  
Khadijeh Cheraghi
Keyword(s):  
Oxygen Consumption ◽  
Crossover Study ◽  
Sodium Nitrate ◽  
Repeated Measures ◽  
Lactate Concentration ◽  
Blood Lactate Concentration ◽  
Time To Exhaustion ◽  
High Dose ◽  
Significance Level ◽  
Double Blinded

The aim of this study was to investigate the effect of different doses of pre-workout sodium nitrate supplementation on nitric oxide, peroxynitrite levels, and performance parameters. Ten well-trained male subjects participated in a randomized, double-blinded, crossover study. They ingested 8, 16, and 24 mmol sodium nitrate or placebo (NaCl) dissolved in water at 2.5 h before an incremental exercise test. Respiratory gases (oxygen consumption, carbon dioxide production, respiratory exchange ratio) were measured throughout the exercise trials and 3 blood samples (pre-ingestion, 2.5 h post-ingestion and postexercise) were taken to analyze nitrate/nitrite (NOx) and peroxynitrite levels. Data were analyzed using repeated-measures ANOVA at significance level of P < 0.05. NOx levels significantly increased following sodium nitrate ingestion compared with placebo (placebo: 40.86 ± 10.7 μmol/L, 8 mmol: 203.69 ± 25.1 μmol/L, 16 mmol: 289.41 ± 30.1 μmol/L, and 24 mmol: 300.95 ± 42.4 μmol/L, respectively) (P = 0.0001). However, this did not induce any significant change in oxygen consumption (P = 0.351), blood lactate concentration (P = 0.245), and time-to-exhaustion (P = 0.147). Peroxynitrite levels were similar compared with placebo when participants ingested 8 and 16 mmol of inorganic nitrate but a significant increase was observed after exercise at maximal intensity when participants were supplemented with 24 mmol (mean = 14.60 ± 1.3 μmol/L, P = 0.001). Pre-workout ingestion of high dose of sodium nitrate (24 mmol) induced peroxynitrate formation, a marker of oxidative stress. Caution must be taken regarding administration of higher doses before benefits or adverse effects are established in this population.

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