HRmax Reserve Research Articles

지속 혹은 분할 유산소 운동방법에 따른 에너지 소비량과 혈중 젖산 농도 비교

The aim of this study was to estimate and compare energy expenditure and blood lactic acid in a 30min continuous bout of bicycle ergometer cycling at 80% of HRmax reserve with 45 min of recovery and in 10 min intermittent bouts of exercise with equally divided into three 15min periods of recovery. Subjects were fourteen college-aged males(age: 22±1.8 years, height: 173±6.5 cm, weight: 70±13.8 kg, %body fat: 19±6.5%) volunteered to participate. Energy expenditure was measured with the POLOR(RS 800CX, Finland) & exercise record/analysis program and Lactate Tester (YSI 1500, USA), at warm up, exercise and during recovery. The 30 min continuous bouts of exercise included a 45 min recovery and each of the three 10 min bouts included 15 min of recovery. Workload was adjusted during exercise to maintain at 80% target HR. Setting of target HR was at 1/3 position of main exercise and maintaining to the end of the exercise. Differences in energy expenditure between continuous and intermittent exercise, recovery from exercise, as well as the combination of exercise an recovery were assessed with a paired t-test. And blood lactic acid concentration were analysis with independent t-test and oneway repeated measures ANOVA were employed to analyse blood lactatic acid. Significance was set a p<.05. The energy expenditure for exercise only was no significantly greater(6.3 kcal) with continuous bout of exercise than intermittent bouts of exercise. On the other hand, during recovery from exercise, they expended more energy(22.7 kcal) following intermittent exercise than following continuous exercise. The total energy expenditure for the combination of exercise and recovery was greater(16.3 kcal) than intermittent bouts of exercise, but it was not significant. And on blood lactic acid, there is significant different at point of exercise finish and at 15min of recovery(p<.01, p<.05 respectively).

Therapeutic Role of Continuous Training Program on High Density Lipoprotein Cholesterol in Men with Hypertension: A Randomized Controlled Trial

Objective: Some of the reported factors that increased the risk for coronary events in hypertensive individuals included elevated total cholesterol (TC) and low density lipoprotein cholesterol (LDL), reduced high density lipoprotein cholesterol (HDL) and physical inactivity. The purpose of the present study was to investigate the effect of interval training programme on blood pressure and lipid profile in subjects with hypertension. Methods: Two hundred and seventeen male patients with mild to moderate (systolic blood pressure [SBP] between 140-180 & diastolic blood pressure [DBP] between 90-109 mmHg) essential hypertension were age matched and grouped into interval and control groups. The interval (n=112; 58.63 ± 7.22 years) group involved in an 8 weeks continuous training (60-79% HR max reserve) programme of between 45minutes to 60 minutes, while age-matched controls hypertensive (n=105; 58.27 ± 6.24 years) group remain sedentary during this period. Cardiovascular parameters (SBP & DBP), VO 2 max, TC, LDL, HDL and Artrogenic Index (AI) were assessed. Students’t test and Pearson correlation test were used in data analysis. Results: Findings of the study revealed significant decreased effect of interval training programme on SBP, DBP, TC, LDL and significant increased effects on VO 2 max and HDL level at p < 0.05. Also there was a significant negative and positive correlation between changes VO 2 max and changes in TC and HDL respectively. Conclusions: it was concluded that interval training programme is an effective adjunct non-pharmacological management of hypertension and a means of normal regulation of lipid profile.

Therapeutic effect of a moderate intensity interval training program on the lipid profile in men with hypertension: A randomized controlled trial

Physical inactivity has been established as a major primary risk factor for the development of hypertension. Also, factors such as elevated total cholesterol (TC) and reduced high density lipoprotein cholesterol (HDL) have been implicated as risk factors for coronary events in hypertension. The purpose of the present study was to investigate the effect of interval training program on blood pressure and lipid profile of subjects with hypertension. A total of 245 male patients with mild-to-moderate hypertension (systolic blood pressure [SBP] between 140 and 180 mmHg and diastolic blood pressure [DBP] between 90 and 109 mmHg) were age matched and grouped into interval and control groups. The interval (n=140; 58.90 ± 7.35 years) group was involved in an 8-week interval training (60-79% HR max reserve) program of between 45 minutes and 60 minutes at a work/rest ratio of 1:1 of 6 minutes each, while the control hypertensive (n=105; 58.27 ± 6.24 years) group remained sedentary during this period. Cardiovascular parameters (SBP and DBP), VO 2 max, TC, HDL, and artrogenic index (AI) were assessed. Student's t-test and Pearson correlation test were used in data analysis. Findings of the study revealed significant decreased effects of the interval training program on SBP, DBP, TC AI, and significant increased effects on VO 2 max and HDL level at P<0.05. There was also a significant correlation between changes VO 2 max and changes in AI. It was concluded that the interval training program is an effective adjunct nonpharmacological management of hypertension and a means of upregulation of HDL.

Effect of interval training program on white blood cell count in the management of hypertension: A randomized controlled study

Objective:Elevated white blood cell (WBC) count is considered to be prospectively and positively associated with cardiovascular diseases, particularly hypertension. Also, the positive role of exercise in the management of hypertension has been well and long established. However the relationship between WBC count and hypertensive management particularly in the nonpharmacological technique is ambiguous and unclear. Therefore the purpose of the present study was to determine the effect of interval training program on WBC count and cardiovascular parameters in male hypertensive patients.Materials and Methods:A total of 245 male patients with mild to moderate (systolic blood pressure (SBP) between 140 mmHg and 179 mmHg and diastolic blood pressure (DBP) between 90 mmHg and 109 mmHg) essential hypertension were age matched and grouped into experimental and control groups. The experimental (n=140; 58.90±7.35 years) group involved in an 8-week interval training (60-79% HR max reserve) program of between 45 minutes to 60 minutes, while the age-matched controls hypertensive (n=105; 58.27±6.24 years) group remain sedentary during this period. Cardiovascular parameters (SBP, DBP, and VO2 max) and WBC count were assessed. Student's t and Pearson correlation tests were used in data analysis.Results:Findings of the study revealed a significant effect of the interval training program on VO2max, SBP, and DBP and WBC count at P<0.05 and VO2max is negatively related to the WBC count (r=–0.339) at P<0.01.Conclusions:It was concluded that the interval training program is an effective adjunct nonpharmacological management of hypertension and the therapeutic effect of exercise programs may be mediated through suppression of inflammatory (WBC count) reaction.

Effect of low intensity continuous training programme on serum uric acid in the non pharmacological management of hypertension: a randomized controlled trial

Elevated serum uric acid (SUA) is considered to be positively associated with cardiovascular event risk factor in hypertension. Also, the positive role of exercise in the management of Hypertension has been well and long established. However the relationship between SUA level and hypertensive management particularly in non pharmacological technique is ambiguous and unclear. Therefore the purpose of the present study was to determine the effect of continuous low intensity training programme on SUA level and cardiovascular parameters in male subjects with hypertension. Two hundred andseventeen male patients with mild to moderate (systolic blood pressure [SBP] between 140-180 & diastolic blood pressure [DBP] between 90-109 mmHg) essential hypertension were age matched and grouped into continuous and control groups. The continuous (n=112; 58.63 +/- 7.22 years) group involved in on 8 weeks interval training (35-9% HR max reserve) programme of between 45 minutes to 60 minutes, while age-matched controls hypertensive (n=105; 58.27 +/- 6.24 years) group remain sedentary during this period. Cardiovascular parameters (SBP, DBP & VO2max) and SUA were assessed. Students' t and Pearson correlation tests were used in data analysis. Findings of the study revealed significant effect of interval training programme on VO2 max, SBP, and DBP and SUA concentration at p < 0.05 and changes in VO2max negatively correlated with SUA (r = -.266) at p < 0.05. it was concluded that low intensity continuous training programme is an effective nonpharmacological management and may prevent cardiovascular event through the down regulation ofSUA in hypertension.

Fluid Balance During Exercise in the Heat

1666 The negative effects of dehydration on health and performance are well documented, but hydration practices during exercise in the heat vary widely among athletes and physically active people; many allow themselves to become dehydrated, while others drink too much for their needs, with potentially negative consequences. There is little research on how personal beliefs and subjective feelings, such as the fear that drinking before or during exercise will cause exercise-related transient abdominal pain (STITCH), influence drinking behavior during exercise. PURPOSE: To assess fluid balance (FB) during moderate exercise in the heat and its association with beliefs regarding drinking fluids and other perceptions during exercise. METHODS: 93 physically active male college students exercised at 60% HRmax reserve for one hour. Each subject alternated stationary cycling, stair climbing, and Nordic Track® skiing in an environmental chamber at 30°C, 70% rh (WBGT = 26.8°C). Voluntary fluid intake (FI) of a cold (8–16°C) sports drink was monitored. Subjects were weighed nude and dry before and after the exercise session. Perceived importance of hydration (IMP) and actual practices, as well as side-stitch beliefs, were evaluated via questionnaire; perception of ambient HEAT, beverage palatability (PAL), stomach fullness (FULL), and gastrointestinal distress (GIPAIN) were assessed at times 25 and 55 min. RESULTS: Fluid balance was −0.14 ± 0.89% (mean ± SD) of initial body mass (bm) (range −2.38 to 2.84%), with a sweat rate (SR) of 1208.3 ± 381.7ml•h-1 and FI of 1132 ± 610 ml•h-1. FB was associated with FI (R2 = 0.73), SR (R2 = 0.08), and IMP (R2 = 0.07) (p<0.01), but not with STITCH, PAL, HEAT or GIPAIN (p>0.05). Overhydrated individuals (FB>0.3%bm) were shorter (p = 0.04) but not lighter (p = 0.33) than dehydrated subjects (FB<-0.3%bm). Their FI was much larger (1700.1 ± 610.7 vs 791.8 ± 451.4ml•h-1, p<0.0005), but their SR was only a little less (1112.8 ± 341.7 vs 1367.3 ± 415.4 ml•h-1, p = 0.01). No significant differences were found between subgroups in any other measure, including STITCH and IMP. CONCLUSION: Overhydration was much more strongly associated with overdrinking than with low sweat rates while IMP was a marginally significant predictor of FB. To maintain proper fluid balance, individuals would be better off relying on an objective drinking plan based on their measured sweat rates than on subjective feelings. Supported by the Gatorade Sports Science Institute and UCR-VI-245-97-002.

Effects of High-intensity Exercise and Fish Oil-induced Oxidative Stress

LANGUAGE NOTE | Document text in Chinese; abstract also in English.High-intensity exercise may induce active oxygen free radicals higher. Fish oil, which is one of the CO-3 PUFA series that can decrease TG and influence plasma lipids, appears to prevent arteriosclerosis and CHD, but some evidence describe it increases the lipid peroxidation in the cell. Fish oil would then seem to influence the antioxidant defense system that causes damage or disease. This study investigates the effects on the antioxidant defence system of combining high-intensity exercise with fish oil supplementation. Methods: Thirty-three healthy males were randomly assigned into four groups (20.3±1.4 yrs; 64.3±7.9 kg), which were given set combinations of dietary fish oil (9 g per day), exercise (intensity 85-90 % HRmax reserve), and placebos. The experiment lasted 4 weeks in total. Venous samples were obtained prior to exercise and within 5 min after. 4 venous samples were also taken from fish oil groups during the four-week period. Blood from all groups was analyzed for sesuperoxide dismutase (SOD), glutathione peroxidase (GSH-Px), total glutathione (T-GSH), total antioxidant ability (TAA), malodialdehyde (MDA). A Generalized Estimating Equations (G.E.E.) method was used for data analysis. Results: In the fish oil groups SOD activity significantly increased 11.27 kU/g-HB(P

Relative heart rate, heart rate reserve, and VO2 during submaximal exercise in the elderly.

The purpose of this study was to examine the relationships among relative maximal heart rate (%HRmax), maximal heart rate reserve (%HRmax reserve), and maximal oxygen uptake (%VO2max) during submaximal exercise by elderly subjects. VO2max and HRmax were determined on 36 women and 19 men, 60 to 80 yrs of age, by a maximal treadmill test to volitional exhaustion. On a separate day, subjects underwent a submaximal treadmill protocol consisting of three 6-min exercise stages at treadmill speeds and grades estimated to elicit 40%, 60%, and 80% of HRmax reserve. Cardiorespiratory responses were determined during mins 4-5 and 5-6 of each stage. Measured exercise intensities expressed by the three methods were: %HRmax reserve = 36, 55, and 79%; %HRmax = 65, 75, and 88%; %VO2max = 53, 69, and 88%. %HRmax was greater (p < .05) than %VO2max at 53 and 69% of VO2max. %HRmax reserve was less (p < .05) than %VO2max for all three intensities. Slopes and intercepts for the linear regression equations relating %VO2max with %HRmax and with %HRmax reserve differed between men and women (p < .05). The regression equation relating %VO2max and %HRmax was y = -22.8 + 1.2 (%HRmax) -13.0 (Gender) + 0.2 (%HRmax x Gender): standard error of the estimate (SEE) = 9.7% and R2 = .71. The regression equation relating %VO2max and %HRmax reserve was y = 32.4 + 0.7 (%HRmax reserve) -10.9 (Gender) + 0.2 (%HRmax reserve x Gender): SEE = 9.8% and R2 = .70 (Gender: F = 0; M = 1). The data indicate that there is considerable variability among methods of expressing exercise intensity and that %HRmax more closely represents %VO2max than does %HRmax reserve (p < .05) in older adults. These results are in contrast to what has been shown with younger subjects and with American College of Sports Medicine guidelines for exercise prescription.

Two‐Year Trends in Cardiorespiratory Function Among Older Tai Chi Chuan Practitioners and Sedentary Subjects

To evaluate the training effects of Chinese shadow boxing, Tai Chi Chuan (TCC), on the maintenance of cardiorespiratory function in older individuals. Prospective study of a cohort of TCC practitioners and a group of sedentary controls examined 2 years after initial examination. Research project at a hospital-based exercise physiology laboratory. Eighty-four community-dwelling older adults (mean age: 64 +/- 9 years) with no significant cardiovascular, pulmonary, and musculoskeletal disease completed this study. The TCC group, 23 male and 22 female subjects, had been practicing TCC regularly for 6.7 +/- 3.3 years. The control group included 21 male and 18 female sedentary subjects with age and body size matched to the TCC group. During the period of the study, the TCC practitioners practiced TCC 5.0 +/- 1.1 times per week. Each session included 20 minutes of warm up, 24 minutes of TCC training, and 10 minutes of cool down. The baseline cardiorespiratory function was recorded in the initial exercise test. The same measurements were repeated 2 years later to determine the rate of decline of cardiorespiratory function. Furthermore, heart rates (HR) were monitored in 18 men and 16 women during the performance of TCC to determine the exercise intensity of TCC. The study measured 2-year trends of cardiorespiratory function in both groups. In the TCC group, the males showed a 2.8% decrease in maximal oxygen uptake (VO2max) from 31.6 +/- 7.6 mL x kg-1 x min-1 to 30.7 +/- 7.1 mL x kg-1 x min-1; the females showed a 2.9% decrease in VO2 max from 20.7 +/- 2.3 mL x kg-1 x min-1 to 20.1 +/- 2.5 mL x kg-1 x min-1. In contrast, the male control group showed a 6.6% decrease in VO2max from 24.4 +/- 4.4 mL x kg-1 x min-1 to 22.8 +/- 4.4 mL x kg-1 x min-1; the females showed a 7.4% decrease in VO2max from 16.2 +/- 2.3 mL x kg-1 x min-1 to 15.0 +/- 2.7 mL x kg-1 x min-1. At the ventilatory threshold (VeT), the sedentary group also showed a significant decrease in VO2. During the steady-state performance of TCC, subjects' mean HR was approximately the HR at the VeT (53-57% of HRmax reserve). The data substantiate that practicing Tai Chi Chuan regularly may delay the decline of cardiorespiratory function in older individuals. In addition, TCC may be prescribed as a suitable aerobic exercise for older adults.

Blood Gas Dynamics at the Onset of Exercise in Heart Transplant Recipients

One hypothesis to explain the rapid neural component of exercise hyperpnea contends that afferent stimuli originating in the ventricles of the heart act reflexly on the respiratory center at the onset of exercise, ie, "cardiodynamic hyperpnea." Orthotopic cardiac transplantation (Tx) results in the loss of afferent information from the ventricles. Thus, Tx possibly results in transient hypercapnia and hypoxemia in deafferented heart transplant recipients (HTR) at the onset of exercise due to hypoventilation. To examine the cardiodynamic hypothesis, we collected serial arterial blood gas (ABG) samples during both the transient and the steady-state responses to moderate cycle exercise in 5 HTRs (55 +/- 7 years) 14 +/- 7 months post-Tx and 5 control subjects matched with respect to gender, age, and body composition. Forced vital capacity, forced expiratory volume in 1 s, total lung capacity, and diffusion capacity did not differ (p > or = 0.05) between groups. Resting arterial PO2, PCO2, and pH did not differ between groups (p > or = 0.05). The ABGs were drawn every 30 s during the first 5 min and at 6, 8, and 10 min of constant load square wave cycle exercise at 40 percent of the peak power output (watts). Absolute and relative changes in arterial PO2, PCO2, and pH were similar (p > or = 0.05) between HTR and the control group at all measurement periods during exercise. Heart rate (%HRmax reserve), rating of perceived exertion, and reductions in plasma volume (% delta from baseline) did not differ between HTR and control during exercise at 40 percent of peak power output (p > or = 0.05). Our results demonstrate that there is no discernible abnormality in ABG dynamics during the transient response to exercise at 40 percent of peak power output in patients with known cardiac denervation. These data do not support the cardiodynamic hyperpnea hypothesis of ventilatory control in humans. The absence of hypercapnia in HTRs is further evidence for the existence of redundant mechanisms capable of stimulating exercise hyperpnea.

Abnormal neuroendocrine responses during exercise in heart transplant recipients.

Osmotic and neural factors stimulate neuroendocrine activity during exercise. In contrast to excitatory mechanisms, afferent information from cardiac mechanoreceptors inhibits integrative centers in the hypothalamus and medula oblongata, which serves to buffer neuroendocrine activity. Orthotopic cardiac transplantation results in the loss of afferent information from cardiac mechanoreceptors. Thus, transplantation possibly results in exaggerated neuroendocrine responses when patients are physically active. We measured the neuroendocrine response to moderate and strenuous exercise performed at the same relative intensity in 11 heart transplant recipients (50 +/- 14 years old) 18 +/- 12 months after transplantation and 11 control subjects matched with respect to sex, age, and body size. Plasma levels of norepinephrine, vasopressin, renin activity, atrial natriuretic peptide, angiotensin II, and aldosterone were measured at rest, during a maximal graded exercise test, and during submaximal exercise at 40% and 70% of peak power output on a cycle ergometer (W). Plasma renin activity and atrial natriuretic peptide were elevated at rest in heart transplant recipients (p < or = 0.05). Heart rate (%HRmax reserve), rating of perceived exertion, and reductions in plasma volume (% delta from rest) at the conclusion of the three exercise conditions did not differ between heart transplant recipients and control (p > or = 0.05). Relative changes in neuroendocrine hormones were similar (p > or = 0.05) in heart transplant recipients and control during exercise at 40% of peak power output. Relative changes in plasma norepinephrine, vasopressin, atrial natriuretic peptide, and plasma renin activity were greater (p < or = 0.05) in heart transplant recipients during exercise at 70% of peak power output and the graded exercise test. We interpret these data as a possible indication of ablation of cardiac mechanoreceptor afferents and unopposed neuroendocrine stimulation in heart transplant recipients. Furthermore, chronic neuroendocrine hyperactivity is likely in ambulatory heart transplant recipients. Although cyclosporine nephrotoxicity is implicated in the development of hypertension, our data suggest that chronic neuroendocrine hyperactivity, which alters renal volume regulation, also contributes to the incidence and severity of hypertension in heart transplant recipients.

Injuries and adherence to walk/jog and resistance training programs in the elderly

To evaluate the effects of 26 wk of aerobic and resistance training on the incidence of injury and program adherence in 70- to 79-yr-old men and women, 57 healthy volunteers (25 males, 32 females) were randomly assigned to a walk/jog (W/J, N = 21), strength (STREN, N = 23), or control (CONT, N = 13) group. Walk/jog training was for 30-45 min, 3 d.wk-1 with intensity equal to 40-70% heart rate max reserve (HRmax reserve) during the first 13 wk, and 75-85% HRmax reserve for weeks 14-26. STREN training consisted of one set (10-12 repetitions) each of 10 variable resistance exercises performed to volitional fatigue. Forty-nine of the original participants completed the training program. Walk/jog training increased VO2max from 22.5 to 27.1 ml.kg-1.min-1 (P less than or equal to 0.05) while STREN and CONT showed no change. STREN improved significantly in chest press and leg extension strength (P less than or equal to 0.05) while W/J and CONT showed no change. Adherence to training was 20/23 (87%) and 17/21 (81%) in STREN and W/J, respectively. One repetition maximum (1-RM) strength testing resulted in 11 injuries in the 57 subjects (19.3%) while STREN training resulted in only two injuries in 23 subjects (8.7%). Walk training during weeks 1-13 resulted in one injury in 21 subjects (4.8%). Eight of 14 subjects (57%) who began jogging intervals at week 14 incurred an injury: two of eight (25%) of the men and all of the women (6 of 6). All W/J training injuries were to the lower extremity.(ABSTRACT TRUNCATED AT 250 WORDS)

Exercise Physiology and Cardiovascular Fitness

Endurance exercise training produces numerous metabolic and cardiovascular effects. Metabolic adaptations include an increase in oxidative capacity of skeletal muscle (greater number and size of mitochondria); an increase in skeletal muscle myoglobin concentration; a greater ability to oxidize fatty acids for energy; and an increase in stored glycogen. Cardiovascular effects of training include a decrease in resting heart rate and heart rate response to submaximal exercise; an increase in resting and exercise stroke volume; an increase in maximal cardiac output; an increase in VO2max; and an increase in arteriovenous oxygen difference. Aerobic exercise training contributes to cardiovascular fitness, because it beneficially alters the coronary artery disease risk profile. An inverse relationship exists between physical fitness and resting heart rate, body weight, percent body fat, serum cholesterol, triglycerides, glucose, and systolic blood pressure. In addition, exercise training increases the high-density lipoprotein fraction of total cholesterol. Endurance exercise is any activity that uses large muscle groups, can be performed continuously, and is rhythmic and aerobic in nature. To develop and maintain cardiovascular fitness, this exercise should be performed at a frequency of 3 to 5 days per week, an intensity of 60% to 90% HRmax or 50% to 85% HRmax reserve, and a duration of 20 to 60 minutes.