Indirect Determination of Maximal Oxygen Consumption (VO2Max) and Its Correlation with Body Mass Index

Background: The current study was designed to evaluate cardio respiratory fitness in terms of VO2max in young healthy males and to correlate between body mass index and cardio respiratory fitness. Methods: One hundred twenty-five apparently healthy male subjects in the age group of 18 to 25 years were included in this study group. Body mass index was measured as weight in kilograms divided by height in meters square. Cardio respiratory fitness in terms of VO2max was predicted by following the protocol of Treadmill Jogging Test (TMJ). Results: There was a highly significant negative correlation between body mass index and VO2max, r = -0.75 p<0.0001. Conclusion: The result suggests that the reduced cardiac performance during progressive work rate exercise in obese individuals. Greater the BMI, more severe will be the functional impairment, suggesting excessive amount of body fat on cardio-respiratory functions and oxygen uptake by working muscles

A Comparative Study Of Cardiovascular Response In Two Acute Submaximal Treadmill Exercise Tests And Its Correlation With Anthropometric Variables

Aim: (i) To assess and compare the cardiovascular response in two sub-maximal exercise tests. (ii) to see correlation between cardiovascular response and anthropometric variables. Method: 125 males 18-25 years underwent first three stages of the original Bruce protocol in one session and exercise according to Treadmill jogging test in another session in randomised order. Heart rate, blood pressure and ECG were recorded before, during and after taking the treadmill test. Results: During the exercise heart rate and systolic BP rose and diastolic BP fell in both the tests. Correlation analysis showed highly significant positive correlation between BMI and pre-exercise systolic BP, post-exercise heart rate and post-exercise systolic BPin both the tests. ECG showed no significant ST/Tor rhythm changes during or after the exercise. Conclusion: Heart rate and BPchanges were more in Bruce submaximal exercise test as compared to treadmill jogging test. Higher BMI was found to be correlated with higher resting systolic BP, higher post-exercise heart rate as well as higher post-exercise systolic BP.

Comparison between incremental shuttle run test and Harvard’s step test on peak exercise performance in healthy males: a cross-sectional study

Background: Cardiovascular fitness is directly related to the physical health of the person. Aerobic capacity (VO2max) is one of the major criteria to decide the cardiovascular fitness of an individual. To help quantify the fitness level by calculating their VO2max, there are various indirect maximal tests available but out of these, which one would predict VO2max better, is a major concern. Hence the purpose of this study was to compare the effects of two indirect maximal tests i.e. Incremental Shuttle Run Test (ISRT) and Harvard’s Step Test (HST) on peak exercise performance in young healthy males.Methods: A cross-sectional study with purposive sampling was performed on healthy untrained 100 males of age group 18-25 years. Day 1 subjects performed ISRT on 20 m track and after a 48 hours rest period, on day 3 same subject performed Harvard’s step test. Pre and post-test parameters (Pulse rate, respiratory rate, systolic and diastolic blood pressure and RPE) were measured and predicted VO2max was calculated.Results: Post-test parameters i.e. PR, RR, SBP significantly increased (p=0.00*) by Harvard’s step test. The diastolic blood pressure did not change significantly (p=0.3) for both the tests. Rating of perceived exertion by both the test was of the range 17-19 (very hard to maximal). Calculated predicted VO2max was significantly more by ISRT than HST in males (p=0.00*).Conclusions: Incremental shuttle run test is more efficient in predicting VO2max than Harvard’s step test in healthy adult’s males.

Strength and power training did not modify cardiovascular responses to aerobic exercise in elderly subjects

Resistance training increases muscle strength in older adults, decreasing the effort necessary for executing physical tasks, and reducing cardiovascular load during exercise. This hypothesis has been confirmed during strength-based activities, but not during aerobic-based activities. This study determined whether different resistance training regimens, strength training (ST, constant movement velocity) or power training (PT, concentric phase performed as fast as possible) can blunt the increase in cardiovascular load during an aerobic stimulus. Older adults (63.9 ± 0.7 years) were randomly allocated to: control (N = 11), ST (N = 13, twice a week, 70-90 percent 1-RM) and PT (N = 15, twice a week, 30-50 percent 1-RM) groups. Before and after 16 weeks, oxygen uptake (VO2), systolic blood pressure (SBP), heart rate (HR), and rate pressure product (RPP) were measured during a maximal treadmill test. Resting SBP and RPP were similarly reduced in all groups (combined data = -5.7 ± 1.2 and -5.0 ± 1.7 percent, respectively, P < 0.05). Maximal SBP, HR and RPP did not change. The increase in measured VO2, HR and RPP for the increment in estimated VO2 (absolute load) decreased similarly in all groups (combined data = -9.1 ± 2.6, -14.1 ± 3.9, -14.2 ± 3.0 percent, respectively, P < 0.05), while the increments in the cardiovascular variables for the increase in measured VO2 did not change. In elderly subjects, ST and PT did not blunt submaximal or maximal HR, SBP and RPP increases during the maximal exercise test, showing that they did not reduce cardiovascular stress during aerobic tasks.

Efeito da inversão dos turnos de trabalho sobre capacidade aeróbia e respostas cardiovasculares ao esforço máximo / Effect of the work shift reversal on the aerobic capacity and cardiovascular responses to maximal exercise

Os distúrbios do sono e alterações associadas atingem grande parte da população que trabalha no turno noturno, afetando a sua qualidade de vida. O objetivo do presente trabalho foi comparar a capacidade aeróbia e as respostas cardiovasculares ao exercício máximo em indivíduos com ciclo sono vigília fisiológico e com inversão dos turnos de trabalho. Foram analisados 18 indivíduos do sexo masculino, sedentários, com idade entre 23-35 anos, divididos em 2 grupos: a) grupo controle, formado por estudantes (n=9) e b) grupo experimental, composto por controladores de tráfego aéreo que trabalhavam com inversão dos turnos de trabalho (n=9). Para a medida da capacidade aeróbia, foi determinado o VO2máx. por meio do analisador de gases metabólicos (VO-2000, Aerosport, Medgraphics). Para o teste de esforço máximo foi realizado o protocolo de rampa em esteira (Millenniun ATL Inbramed) e as respostas cardiovasculares (FC, PAS e PAD) foram verificadas antes e após a realização do exercício. De acordo com os resultados, o grupo experimental apresentou valores inferiores de FC no repouso (79,8 ± 11,5 bpm vs. 70,3 ± 3,8 bpm), no 5º (112,7± 15,1 bpm vs. 98,7 ± 6,3 bpm) e no 7º minuto (108,7 ± 16,6 bpm vs. 93,9 ± 6,8 bpm) de recuperação. Quanto à PAS, foram observados valores superiores durante o repouso (110,0 ± 11,2 mmHg vs. 104,0 ± 5,7 mmHg), nos indivíduos do grupo controle. Já a PAD, mostrou níveis superiores no 5º minuto da recuperação no grupo experimental (67,0 ± 4,4 mmHg vs. 58,9 ± 6,0 mmHg). Por fim, foram verificados valores superiores de VO2máx. para os indivíduos do grupo controle (58,9 ± 6,1 ml/kg/min) em relação ao experimental (53,7 ± 2,5 ml/kg/min). Desta forma, podemos concluir que a inversão nos turnos de trabalho, afetando o ciclo sono-vigília, altera não apenas o ciclo circadiano das variáveis cardiovasculares no repouso e na recuperação do esforço, como também traz prejuízos à capacidade funcional, podendo comprometer o desempenho...

Sleep disturbs and associated alterations reach great part of the population which works at night, affecting their quality of life. The aim of the present study was to compare the aerobic capacity and the cardiovascular responses to maximal exercise in subjects with physiological sleep/wake cycle and with work shift inversion. 18 male subjects, aged 23-35 years, were assigned to either a shift-workers (Experimental; n=9) or a control group (Control; n=9). All the subjects underwent a treadmill exercise test in order to obtain the BP, HR behavior in the recovery period. Exhaled air was collected every 10 minutes for VO2max. Shift-workers presented lower heart rate values at rest (79.8 ± 11.5 bpm vs. 70.3 ± 3.8 bpm), 5th (112.7 ± 15,1 bpm vs. 98,7 ± 6,3 bpm) and 7th min. (108.7 ± 16.6 bpm vs. 93.9 ± 6.8 bpm) at recovery. SBP showed significant increased values in control group just at rest (110.0 ± 11.2 mmHg vs. 104.0 ± 5.7 mmHg). The control group presented lower values of DBP at the 5th min. (67.0 ± 4.4 mmHg vs. 58.9 ± 6.0 mmHg) and higher values of VO2max. (58.9 ± 6.1 ml/kg/min vs. 53.7 ± 2.5 ml/kg/min). We concluded that the alterations in the working shifts affect the circadian rhythms and the cardiovascular variables at rest and recovery periods of the exercise stress testing and can compromise the functional capacity of the subjects.

Physiological responses during pushing of a racing-wheelchair in athletes with spinal cord injury / 体力科学

The purpose of this study was to investigate the physiological responses during pushing of a racing-wheelchair. Five subjects with spinal cord injury (T4-L1) participated in two experiments. In the first experiment, the subjects pushed a racing-wheelchair mounted on a roller. Pulmonary ventilation (VE), oxygen uptake (VO<SUB>2</SUB>), heart rate (HR), blood lactate concentration (LA), and rating of perceived exertion (RPE) were measured to examine the physiological responses during submaximal and maximal tests of wheelchair exercise. The mean value of %VO<SUB>2</SUB>max at ventilatory threshold (VT) was 60.7±5.3%. VO<SUB>2</SUB> increased curvilinearly with speed, and HR increased with speed, forming an S-shape. HR increased linearly with increasing VO<SUB>2</SUB> before the VT, then showed a steeper parabolic rise to almost maximum, followed by a flat phase. In the second experiment, during 1500-m and 5000-m wheelchair races and a half-marathon, VE, VO<SUB>2</SUB>, and HR were measured to reveal the physiological characteristics of wheelchair racing as a competitive sport. During the 1500-m and 5000-m races by four subjects, the mean values of %VO<SUB>2</SUB>max were 73.1±7.3% and 66.0±13.3%, respectively. During the half-marathon by one subject, %VO<SUB>2</SUB>max reached 72.1%. These data suggest that wheelchair endurance athletes compete at very high intensity (over VT level) in wheelchair races.

Respiratory Gas Exchange and Ventilatory Functions at Maximal Exercise / 결핵

BACKGROUND: Although graded exercise stress tests are widely used for the evaluation of cardiorespiratory performance, normal standards on respiratory gas exchange and ventilatory functions at maximal exercise in Koreans have not been well established. The purpose of this study is to provide reference values on these by sex and age, along with derivation of some of their prediction equations. METHOD: Symptom-limited maximal exercise test was carried out by Bruce protocol in 1,000 healthy adults consisting of 603 males and 397 females, aged 20~66 years. Among them VC, FEV1 and MVV were also determined in 885 cases. All the subjects were members of a health center, excluding athletes. During the exercise, subjects were allowed to hold on to front hand rail of the treadmill for safety purpose. RESULTS: The VO2 max/m2, VCO2 max/m2 and VE max/m2 were greater in males than in females and decreased with age. The RR max in men and women was similar but decreased slightly with age. The VT max was markedly greater in men but showed no significant changes with age in either gender. The mean of VT max/VC, VE max/MVV and BR revealed that there were considerable ventilatory reserves at maximal exercise even in older females. The regression equations of the cardinal parameters obtained using exercise time(ET, min), age(A, yr), height(Ht, cm), weight(W, kg), sex(S, 0=male; l=female), VC(L), FEV1(L) and VE max(L) as variables are as follows: VO2 max/m2(L/min)=1.449+0.073 ET-0.007A+0.010W-0.006Ht-0.209S, VCO2 max/m2(L/min)= 1.672+0.063ET-0.008A + 0.010W -0.005Ht -0.319S, VE max/m2(L/min)=58.161 +1.503ET - 0.315A-9.871S or VE max/m2(L/min)=47.873+6.548 FEV1-5.715 S, and VT max(L)=1.497+ 0.223VC-0.493S. CONCLUSION: Respiratory gas exchange and ventilatory variables at maximal exercise were studied in 1,000 non-athletes by Bruce protocol. During exercise, the subjects were allowed to hold on to hand rail of the treadmill for safety purpose. We feel that our results would provide ideal target values for patients and healthy individuals to be achieved, since our study subjects were members of a health center whose physical fitness levels were presumably higher than ordinary population.

Effects of changing daily exercise habit on body composition and maximal exercise test. One-year follow-up study of healthy males and males with mild hypertension / 体力科学

The effects of changing daily exercise habit on body fat, serum lipids and symptom-limited maximal exercise test (treadmill by Balke protocol) were evaluated in healthy males and males with mild hypertension (MHT) aged 30 to 59 yr during a period of one year. The subjects were selected from males who underwent physical examination. The results were as follows :<BR>A. HEALTHY MALES<BR>Study 1 : Subjects who exercised regularly (3 times or more/week) showed higher exercise tolerance and HDL cholesterol (HDLC) and less body fat. Compared to inactive subjects (sports 0-2 times/week), exercise tolerance was higher in the group who tried to walk as much as possible in their every day life.<BR>Study 2 : Inactive subjects without a family history of HT were classified by percentage body fat into three groups (H, M and L) . The obese group showed lower exercise tolerance, higher total cholesterol (TC) and lower HDLC. Heart rate (HR) and systolic blood pressure (BPs) at the same load during the exercise test were higher in the obese group.<BR>Study 3 : Revisited subjects who did not change their dietary habit for one year were selected from the average group of study 2. The subjects who increased their daily physical activity showed reduced body weight and body fat, increased exercise tolerance and HDLC, and lower HR and BPs under the same work load.<BR>B. MALES WITH MILD HYPERTENSION<BR>Study 4 : A similar study was conducted in inactive men with MHT (diastolic BP 90-104 mmHg), non-drug therapy at the first visit and no change in dietary habit for one year. Subjects who increased their daily activity for one year showed reduced body weight and body fat, and both resting BPs and BPd fell by 7 mmHg. HR and BPs decreased under the same work load.<BR>These results suggest that an increase in daily physical activity improves physical fitness, reduces blood pressure and decreases body fat in previously healthy males and in males with MHT.

Effects of Intensive Training on Cardiorespiratory Response to Maximal Exercise Loading in Soccer Players

BACKGROUND: In order to investigate the effects of intensive training on cardiorespiratory response to maximal exercise in soccer players, graded excercise stress tests were carried out before and after the training, and the results were compared. METHODS: Fourteen male soccer players of a university team with the mean age and career of 19.9 and 7.8 years, respectively, underwent intensive training for approximately 20 weeks, 6 days a week and 4 hours a day, which included running of 2 km daily during the last 8-9 weeks. The symptom-limited maximal exercise test was done by Bruce protocol. RESULTS: After the training. HR max showed no significant changes but Vo2 max, O2 pulse and AT were increased approximately 13%, 12% and 10%, respectively. At maximal exercise, the V(E)/M2 was also increased 18%, but VE/MVV was significantly decreased owing to a marked increase in MVV. However, the rest of various ventilatory parameters showed no significant changes. CONCLUSION: These data indicate that the intensive training of about 20 weeks duration can further improve the level of cardiorespiratory fitness in the soccer players who have been regularly trained and are already highly fit.

Evaluation of methods used to determine anaerobic work capacity by blood lactate and oxygen debt / 体力科学

A study was conducted to examine the efficacy of indicators of anaerobic work capacity or estimations of anaerobic energy expenditure by measuring Δ blood lactate and O<SUB>2</SUB> debt after short-term maximal exercise. Eight male subjects performed cycle ergometer pedaling against 5.5-7.0 kp resistance with maximal effort for 45 s. After pedaling, venous blood samples were drawn serially at 1 min intervals from 1 to 10 min, for measurement of peak blood lactate. Anaerobic energy expenditure was determined in terms of both alactacid and lactacid energy expenditure, on the basis of Δ blood lactate (L-method) and O2 uptake kinetics (D-method) during recovery.<BR>The following results were obtained:<BR>1) The correlation coefficient between lactate and performance was higher (about 0.3-0.5) when lactate was expressed as the estimated value of lactate production rather than Δ blood lactate. A significant relationship (r=0.740, p<0.05) was found between lactate production and peak power.<BR>2) When O<SUB>2</SUB> uptake after recovery for 60 min did not recover to the baseline of O<SUB>2</SUB> uptake at rest, O<SUB>2</SUB> debt was calculated using a baseline of O<SUB>2</SUB> uptake just before the end of recovery. This O<SUB>2</SUB> debt was significantly correlated with work at any time of recovery.<BR>3) There was a significant relationship between lactate production and lactic O<SUB>2</SUB> debt, which was significantly correlated with work.<BR>4) When lactacid energy was calculated using a formula of 1.7×Δ blood lactate and 0.3 kcal/g lactate, there was no significant difference between anaerobic energy expenditure calculated by the L- and D-methods for up to 30 min during recovery.<BR>It was concluded that a) the estimated value of lactate production and O<SUB>2</SUB> debt calculated using a baseline of O<SUB>2</SUB> uptake just before the end of recovery could be employed as an indicator of anaerobic work capacity, and b) Δ La multiplied by a coefficient of 1.7 and 0.3 kcal/g lactate was more appropriate for estimating anaerobic expenditure in short-term maximal cycle ergometer pedaling.