Safety and feasibility of atropine added to submaximal exercise stress testing with Tl-201 SPECT for the diagnosis of myocardial ischemia

BACKGROUND: We aimed to assess whether atropine administration is safe and feasible in patients unable to reach the minimal heart rate (HR) required (80% of age-predicted HR) in myocardial scintigraphic studies after exercise stress testing (EST). METHODS AND RESULTS: We studied 108 patients who underwent myocardial perfusion scintigraphy after EST; 0.5 mg of atropine was administered to those showing signs of fatigue before reaching minimal HR (group A, n = 44). The scintigraphic results for group A were compared with those of patients who spontaneously achieved minimal HR (group B, n = 64). Coronary angiographic results, if available, and clinical follow-up were also compared. In group A, atropine increased HR by 13.7 +/- 7.4 beats/min. The percentage of maximal age-related HR achieved was 83.3% +/- 7.5%; 74% achieved minimal HR. No major adverse effects occurred. When groups A and B were compared, baseline and peak HR, rate pressure product, and maximal metabolic equivalents achieved were higher in group B. There were no differences in number of perfusion studies positive for ischemia (group A, 26/44, and group B, 30/64; P =.2), coronary lesions, or clinical follow-up. CONCLUSIONS: Atropine added to EST in patients who cannot achieve their 80% age-related HR is a safe and potentially useful method for myocardial perfusion studies.     

Exercise intensity during competition time trials in professional road cycling

PURPOSE: To estimate, upon competition heart rate (HR), exercise intensity during time trials (TT) in professional road cycling. METHODS: Eighteen world-class cyclists completed an incremental laboratory cycling test to assess maximal power output (Wmax), maximal HR (HRmax), onset of blood lactate accumulation (OBLA), lactate threshold (LT), and a HR-power output relationship. An OBLA(ZONE) (HR(OBLA) +/- 3 beats x min(-1)) and a LT(ZONE) (HR(LT) +/- 3 beats x min(-1)) were described. HR was monitored during 12 prologue (<10 km, PTT), 18 short (<40 km, STT), 19 long (>40 km, LTT), eight uphill (UTT), and seven team (TTT) time trials. A HR-power output relationship was computed to estimate each cyclist's power output during TT racing from competition HR. Competition training impulse (TRIMP) values were estimated from HR and race duration. RESULTS: %HRmax were 89+/-3%, 85+/-5%, 80+/-5%, 78+/-3%, and 82+/-2% in PTT, STT, LTT, UTT, and TTT, respectively. The amount of TRIMP were, respectively, 21+/-3, 77+/-23, 122+/-27, 129+/-14, and 146+/-6. Competition HR values relative to HR(OBLA) and HR(LT) were, respectively, 100+/-3%, 114+/-8% in PTT, 95+/-7%, 108+/-9% in STT, 89+/-5%, 103+/-8% in LTT, 87+/-2%, 101+/-5% in UTT, and 91+/-4%, 105+/-11% in TTT. CONCLUSIONS: %HRmax, TRIMP and time distribution around HR(OBLA) and HR(LT) reflected the physiological demands of different TT categories. HR(OBLA) and HR(LT) were accurate intensity markers in events lasting, respectively, < or =30 (PTT and STT) and > or =30 min (LTT, UTT, TTT).     

The ventilatory threshold, heart rate, and endurance performance: relationships in elite cyclists

The purpose of this study was to investigate the validity of the ventilatory response during incremental exercise as indication of endurance performance during prolonged high-intensity exercise under field test conditions in elite cyclists. The ventilatory threshold (VT) was assessed in 14 male elite cyclists (age 22.4+/-3.4 years, height 181+/-6 cm, weight 69.2+/-6.8 kg, VO2max 69+/-7 ml x min(-1) x kg(-1)) during an incremental exercise test (20 W x min(-1)). Heart rate and oxygen uptake were assessed at the following ventilatory parameters: 1. Steeper increase of VCO2 as compared to VO2 (V-slope-method); 2. Respiratory exchange ratio (RQ)=0.95 and 1.00; 3. VE/VO2 increase without a concomitant VE/VCO2 (VE/VO2 method). Three weeks following the laboratory tests, the ability to maintain high-intensity exercise was determined during a 40 km time trial on a bicycle. During this time trial the mean heart rate (HR(TT)) and the road racing time (TT) were assessed. The V-slope-method and the VE/VO2 method showed significant correlations with TT (V-slope: r = -0.82; p<0.001; 90% interval of confidence = +/-82 sec; VE/VO2: r=-0.81; p<0.01; 90% interval of confidence = +/-81 sec). Heart rate at the ventilatory parameters and at the maximum heart rate (HRmax) showed significant correlations with HR(TT). The V-slope-method is the preferred method to predict heart rate during prolonged high-intensity exercise (r=0.93; p<0.0001; 90% interval of confidence: +/-4.8 beats x min(-1)). For predicting heart rate during prolonged high-intensity exercise using an incremental exercise test (20 W x min(-1)), without the knowledge of ventilatory parameters, we recommend using the regression formula: H(TT)=0.84 x Hmax + 14.3 beats x min(-1) (r=0.85; p<0.001).     

Pathophysiology of cardiac transplantation and the challenge of exercise

Heart transplantation is now currently performed in adult (A-HTR) as well as in pediatric cardiac patients (P-HTR). In A-HTR, heart denervation results in a delayed, blunted heart rate (HR) response to exercise onset, mainly sustained by the level of circulating catecholamines. At the offset of exercise HR resumes the pre-exercise level in 5-25 min, depending on the absolute work intensity. Peak HR is approximately 140 beats/min. Maximal aerobic power is 19 O2/kg x min, i.e., approximately 60% than that of healthy age-matched sedentary subjects and exercise tolerance is therefore reduced. A functional impairment at the muscle level may also be present, as suggested by the slow kinetics of the VO2 readjustment (phase II) at the onset of submaximal aerobic exercise. P-HTR generally behave as A-HTR. However, recently, in a few P-HTR a fast HR response to exercise and greater peak HR values (172 +/- 22 beats/min) were demonstrated. Maximal aerobic power of P-HTR was 32 +/- 7 ml O2/kg x min, greater than that of A-HTR, but yet approximately 60% of that of healthy age-matched controls. It may be concluded that occasionally P-HTR may resume an almost normal cardiovascular response to exercise; nevertheless, their exercise tolerance is limited, likely by functional impairment at the muscle level, whose origin is still unknown.     

Physical activity level during a round of golf on a hilly course

BACKGROUND: Regular physical activity plays a role in preventive medicine. Our study aimed at establishing the duration of different levels of exercise intensity during a round of golf. METHODS: Participants: we studied 21 male and 9 female golfers (mean age 53 +/- 11 and 54 +/- 13 years respectively) volunteering for a round of golf on a hilly course. Measures: we recorded mean heart rate (HR) of every 15 seconds. Blood pressure was taken on each tee. Maximum HR (HRmax) reserve of each subject was calculated from the difference between pre-exercise and maximum HR attained during a test to volitional exhaustion on a cycle ergometer. A percentage of this value was added to the resting HR and was expressed as a percentage of HRmax reserve. RESULTS: Before start mean HR (+/- SD) was 86 +/- 11 beats per minute (BPM), during play 113 +/- 18, and during rest after play 100 +/- 24 BPM. Mean maximal HR of holes were 135 +/- 21 BPM. Mean systolic blood pressure was 145 +/- 30 before play, 137 +/- 31 on tees during play and 119 +/- 15 mmHg after play. A mean of 82 +/- 51 minutes was spent at 50-74% of HRmax reserve. 21 +/- 27 and 23 +/- 38 minutes were spent in the two higher intensity classes. An average of 106 +/- 77 minutes were spent at or above the individual heart rate equivalent of 100 W, the mean heart rate for this time was 128 +/- 17 BPM. Creatine kinase (+47%; p < 0.001), uric acid (+9%; p < 0.001) and HDL-cholesterol (+6%; p < 0.05) increased, triglycerides decreased by 18% (p < 0.01). CONCLUSIONS: The HR level during the golfround not using an electric cart relative to the maximum attained on the ergometer reaches the exercise intensity of 50 to > 85% HRmax reserve for a mean of over 2 hours, much longer than the 20-60 min recommended for endurance training.     

Energy expenditure by heart rate in children: an evaluation of calibration techniques

PURPOSE: To evaluate the impact of applying seven calibration equations (CE) in the estimation of free-living total energy expenditure (TEE) over 2-3 d in seven boys (mean +/- SD age 9.4+/-0.4 yr) by the Flex heart rate (HR) method. METHODS: HR and oxygen consumption were measured simultaneously for eight activities (lying, sitting, standing, arm-reaching exercise, a stooping-and-twisting exercise, stepping, treadmill walking/running, and cycle ergometry) carried out in sequence. CE were derived from various combinations of activities. Flex HRs were identified for each CE. RESULTS: There were no significant differences in TEE estimates [range (mean +/- SD); 6.65+/-0.72 to 7.27+/-0.89 MJ x d(-1)] derived from any of the CE. Mean daytime HR ranged from 86+/-4 to 122+/-15 beats x min(-1), and 82-98% of recorded daytime HR was < or = 140 beats x min(-1). As a result, within-subject CV in TEE from each of the CE ranged from 2.2% to 8.9%. Mean between-subject Flex HR ranged from 94+/-8 to 111+/-8 beats x min(-1). No significant differences were observed in corresponding TEE estimates. However, mean activity energy expenditure (AEE) ranged from 2.10+/-1.18 MJ x d(-1) (based on Flex HR 111+/-8 beats-min(-1)) to 3.55+/-1.44 MJ x d(-1) (based on Flex HR 94+/-8 beats x min(-1); NS). The corresponding estimates of resting energy expenditure (REE) were 1.89+/-0.82 MJ x d(-1) (Flex HR 111+/-8 beats-min(-1)) and 1.05+/-0.60 MJ x d(-1) (Flex HR 94+/-8 beats x min(-1)). Only the differences between the minimum and maximum estimates of REE were significant (P < 0.05). CONCLUSIONS: Unduly lengthy and complex calibration procedures for the estimation of Flex HR TEE may not be justified in most cases, particularly in sedentary children.     

NOS3 gene polymorphisms and exercise hemodynamics in postmenopausal women

We tested whether the G894T and T-786C NOS3 polymorphisms were associated with exercise cardiovascular (CV) hemodynamics in sedentary, physically active, and endurance-trained postmenopausal women. CV hemodynamic parameters including heart rate (HR), systolic (SBP) and diastolic (DBP) blood pressures and cardiac output (Q), as determined by acetylene rebreathing, stroke volume (SV), arteriovenous oxygen difference (a-vO2 diff), and total peripheral resistance (TPR) were measured during submaximal (40, 60, 80 %) and maximal (approximately 100 % VO2max) exercise. NOS3 G894T genotype was not significantly associated, either independently or interactively with habitual physical activity (PA) level, with SBP, Q, TPR, or a-vO2 diff during submaximal or maximal exercise. However, NOS3 894T non-carriers had a higher submaximal exercise HR than NOS3 894T allele carriers (120 +/- 2 vs. 112 +/- 2 beats/min, p = 0.007). NOS3 894T allele carriers had a higher SV than 894T non-carriers (78 +/- 2 vs. 72 +/- 2 ml/beat, p = 0.03) during submaximal exercise. NOS3 894T non-carriers also had a higher maximal exercise HR averaged across habitual PA groups than T allele carrier women (165 +/- 2 vs. 158 +/- 2 beats/min, p = 0.04). NOS3 894T allele carriers also tended to have a higher SV during maximal exercise than 894T non-carriers (70 +/- 2 vs. 64 +/- 2 ml/beat, p = 0.08). NOS3 T-786C genotype was not significantly associated, either independently or interactively, with any of the CV hemodynamic measures during submaximal or maximal exercise. These results suggest an association of NOS3 G894T genotype with submaximal and maximal exercise CV hemodynamic responses, especially HR, in postmenopausal women.     

Laboratory blood lactate profile is suited to on water training monitoring in highly trained rowers

AIM: This study validated the laboratory testing used to monitor on water training. The purpose was to test that reference heart rates (HR) determined during an incremental test elicit comparable blood lactate levels ([La](b)) during a 30 min on water rowing. METHODS: Blood lactate profile were determined during incremental graded exercise in 14 national and international level oarsmen. The HR corresponding to [La](b) of 2 and 3 mmol x l(-1) were determined (HRLa2 and HRLa3 respectively). The rowers then performed a 30 min training session in a boat. Training intensity, as assessed by HR monitors, had to range between HRLa2 and HRLa3. Field [La](b) (Laf) and HR (HRf) were measured at the end of the training session. RESULTS: Laf was 2.13+/-0.49 mmol x l(-1) (range: 1.43-3.07) and did not differ significantly from 2 mmol x l(-1). HRf (162+/-7.4 beats x min(-1)) ranged from HRLa2 (159+/-9.5 beats x min(-1)) to HRLa3 (171+/-9 beats x min(-1)). HRf was not significantly different from HRLa2. CONCLUSIONS: It was concluded that the HR determined during the laboratory testing are valid for monitoring on water training in highly trained rowers.     

Heart rate and performance parameters in elite cyclists: a longitudinal study

PURPOSE: This study was designed to evaluate the stability of target heart rate (HR) values corresponding to performance markers such as lactate threshold (LT) and the first and second ventilatory thresholds (VT1, VT2) in a group of 13 professional road cyclists (VO2max, approximately 75.0 mL x kg(-1) x min(-1)) during the course of a complete sports season. METHODS: Each subject performed a progressive exercise test on a bicycle ergometer (ramp protocol with workload increases of 25 W x min(-1)) three times during the season corresponding to the "active" rest (fall: November), precompetition (winter: January), and competition periods (spring: May) to determine HR values at LT, VT1 and VT2. RESULTS: Despite a significant improvement in performance throughout the training season (i.e., increases in the power output eliciting LT, VT1, or VT2), target HR values were overall stable (HR at LT: 154 +/- 3, 152 +/- 3, and 154 +/- 2 beats x min(-1); HR at VT1: 155 +/- 3, 156 +/- 3, and 159 +/- 3 beats x min(-1); and at VT2: 178 +/- 2, 173 +/- 3, and 176 +/- 2 beats x min(-1) during rest, precompetition, and competition periods, respectively). CONCLUSION: A single laboratory testing session at the beginning of the season might be sufficient to adequately prescribe training loads based on HR data in elite endurance athletes such as professional cyclists. This would simplify the testing schedule generally used for this type of athlete.     

RPE during prolonged cycling with and without carbohydrate ingestion in boys and men

PURPOSE: To examine the effect of prolonged cycling on ratings of perceived exertion (RPE) in boys and men and whether carbohydrate (CHO) ingestion would lower RPE during exercise. METHODS: Ten boys (9-10 yr) and 10 men (20-25 yr) cycled for 60 min at approximately 70% VO2peak on two occasions. In a double-blind, counterbalanced design, a total volume of 24 mL.kg(-1) body mass of either a 6% CHO-electrolyte (CT) or flavored water (WT) beverage was consumed intermittently before and during exercise in each trial. Oxygen consumption (VO2), ventilation (VE), respiratory rate (RR), RPE (Borg's 6-20 scale), and heart rate (HR) were recorded periodically throughout exercise. Plasma glucose (GLU) was determined before and after exercise. RESULTS: Postexercise GLU was not different between age groups but higher (P<0.001) during CT (5.6 +/- 0.2 mmol.L(-1)) compared with WT (4.7 +/- 0.1 mmol.L(-1)). CHO ingestion had no effect (P>0.05) on VO2, VE, RR, or RPE in either group. RR during exercise was higher (P<0.01) in boys (39.0 +/- 2.2 breaths.min(-1)) than in men (30.9 +/- 1.3 breaths.min(-1)). HR was slightly higher (P=0.047) during CT (160 +/- 3 beats.min(-1)) compared with WT (156 +/- 4 beats.min(-1)) and increased less over time (P<0.01) in boys compared with men. RPE at 5 min of exercise was similar (P>0.05) between boys (11.8 +/- 0.7) and men (12.0 +/- 0.7) but increased faster (P<0.01) over time in boys. The average exercise RPE was higher (P<0.01) in boys (15.8 +/- 0.5) than in men (14.0 +/- 0.4). CONCLUSIONS: The higher and faster increase in RPE during exercise in boys, compared with men, may reflect a sensitivity to RR that outweighed any effect of CHO ingestion on RPE.     

Effects of resistance exercise bouts of different intensities but equal work on EPOC

PURPOSE: To compare the effect of low- and high-intensity resistance exercise of equal work output, on exercise and excess postexercise oxygen consumption (EPOC). METHODS: Fourteen female subjects performed a no-exercise baseline control (CN), and nine exercises for two sets of 15 repetitions at 45% of their 8-RM during one session (LO) and two sets of 8 repetitions at 85% of their 8-RM during another session (HI). Measures for all three sessions included: heart rate (HR) and blood lactate (La) preexercise, immediately postexercise and 20 min, 60 min, and 120 min postexercise; and ventilation volume (VE), oxygen consumption (VO(2)), and respiratory exchange ratio (RER) during exercise and at intervals 0-20 min, 45-60 min, and 105-120 min postexercise. RESULTS: Exercise .VO(2) was not significantly different between HI and LO, but VE, [La], and HR were significantly greater for HI compared with LO. Exercise RER for HI (1.07 +/- 0.03 and LO (1.05 +/- 0.02) were significantly higher than CN (0.86 +/- 0.02), but there were no differences among conditions postexercise. EPOC was greater for HI compared with low at 0-20 min (HI,1.72 +/- 0.70 LO(2); LO, 0.9 +/- 0.65, LO(2)), 45-60 min (HI, 0.35 +/- 0.25 LO(2); LO, 0.14 +/- 0.19 LO2), and 105-120 min (HI, 0.22 +/- 0.22 LO(2); LO, 0.05 +/- 0.11, LO(2)). CONCLUSION: These data indicate that for resistance exercise bouts with an equated work volume, high-intensity exercise (85% 8-RM) will produce similar exercise oxygen consumption, with a greater EPOC magnitude and volume than low-intensity exercise (45% 8-RM).     

Post-exercise palpation of pulse rates: its applicability to habitual exercisers

Despite the increased popularity of heart rate (HR) monitors, endurance-trained adults as well as habitual exercisers often use pulse rate palpation to periodically monitor exercise intensity. However, due to the rapid recovery of HR following exercise bouts, post-exercise palpation of pulse rates may underestimate exercise HR. To test this hypothesis, we studied 20 young physically active adults performing two sets of exercise for 5 min at 70% and 85% of maximal HR on the treadmill; one with carotid and another with radial pulse count. Post-exercise palpation of pulse rate was lower (P < 0.01) than the actual HR during exercise, underestimating exercise HR by 20-27 bpm (beats per min). Even when ECG tracings of HR were analyzed immediately after exercise (0-15 s), a significant underestimation of exercise HR (7-9 bpm) still persisted (P < 0.05). Following exercise, pulse rate obtained by carotid palpation at both intensities and radial palpation at the lower intensity was no different from the corresponding HR measured with ECG. In the radial artery trial at the higher exercise intensity, pulse rate following exercise was lower (10 bpm; P < 0.05) than ECG-derived HR. Arterial stiffness, which is closely associated with arterial baroreflex sensitivity, was not significantly related to the changes in HR with carotid palpation. We concluded that post-exercise pulse palpations may not be appropriate as an indicator of exercise intensity in habitual exercisers.     

Exercise intensity during off-road cycling competitions

PURPOSE: This study was designed to quantify and describe the intensity profile of cross-country mountain-biking races using heart rate (HR) recorded during competitions. METHODS: Nine mountain bikers participated in four cross-country circuit races of international and national levels. Each cyclist was tested before the competitions to determine lactate threshold (LT), the onset of blood lactate accumulation (OBLA4), and the relationship between percentage of maximum HR and percentage of VO(2max). RESULTS: To control for intersubject variability, only the five off-road cyclists who completed all four competitions were included in the statistical analysis. The four races' mean absolute and relative time expressed in percentage of race duration (147 +/- 15 min) spent in the EASY(ZONE) (HR below LT) were 27 +/- 16 min and 18 +/- 10%, in the MODERATE(ZONE) (HR between LT and OBLA4) were 75 +/- 19 min and 51 +/- 9%, and in the HARD(ZONE) (HR above OBLA4) were 44 +/- 21 min and 31 +/- 16%. The average HR was 171 +/- 6 beats x min(-1), corresponding to 90 +/- 3% of maximum (84 +/- 3% of VO(2max). CONCLUSION: This study shows that cross-country events are conducted at very high intensity, especially at the start of the race. Coaches must take into account the distribution of the effort and the high exercise intensity characteristic of mountain-biking cross-country events when prescribing specific training programs.     

Relationship of heart rate to oxygen uptake during weight lifting exercise

To define the relation of heart rate to oxygen uptake during weight lifting (WL), heart rate (HR) and oxygen uptake (VO2) were determined during bouts of WL at four intensities (40, 50, 60, and 70% of one-repetition maximum (1-RM)) in 15 males. The 11.5-min bouts of WL consisted of three circuits using four exercises (bench press, bent-over row, arm curl, and parallel squat), with each performed for ten repetitions over a 30-s period with a 1:1 work/rest ratio. During lifting at the four intensities, mean (+/- SE) VO2 values were 1.31 +/- 0.04, 1.50 +/- 0.07, 1.72 +/- 0.07, and 1.86 +/- 0.08 l.min-1, or 33-47% of treadmill-determined VO2max. Mean (+/- SE) HR values were 124 +/- 4, 134 +/- 4, 148 +/- 5, and 161 +/- 4 beats.min-1, or 63-82% of maximal HR. The slope of the linear regression equation predicting %VO2max from %HRmax (Y = 0.582X - 1.7911, r = 0.86, SEE = 3.4%) was approximately half that reported for dynamic low-resistance exercise such as running or cycling. At a given %HRmax, %VO2max was consistently lower than predicted for dynamic low-resistance exercise. It was concluded that the HR/VO2 relationship during dynamic high-resistance exercise for intensities between 40 and 70% of 1-RM is linear but is different from that reported for dynamic low-resistance exercise. The data are consistent with the conclusion in previous studies that using HR to prescribe the metabolic intensity of WL exercise results in a substantially lower level of aerobic metabolism than during dynamic low-resistance exercise.     

Heart rate responses at onset of contraction

We tested the hypothesis that the initial heart rate (HR) response at the onset of maximal handgrip contraction is altered after training. 17 volunteers (nine trained and eight controls) performed ten intermittent static handgrip contractions with maximal effort, alternating between 15-s contractions and 15-s pauses. High-intensity static handgrip training was performed using the nondominant arm alone for 4 weeks. Handgrip force (HGF) and HR were analyzed for the initial 7 s of every static handgrip exercise. Peak HR (pre-training: 94.5 +/- 12.8 beats/min; post-training: 89.7 +/- 10.2 beats/min, p < 0.05) decreased. However, the magnitude of HR change at the onset of contraction remained constant (pre-training: 23.0 +/- 7.7 beats/min; post-training: 25.7 +/- 6.5 beats/min, p = 0.0767), while the HR responses in the subsequent bouts increased after training (p < 0.001). The resting HR decreased (pre-training: 71.5 +/- 9.3 beats/min; post-training 64.1 +/- 5.7 beats/min, p < 0.05). Maximal HGF increased by 11.1 % in trained arms and by 8.7 % in untrained arms, although an increase in maximal forearm girth was only observed in the trained arm (2.0 %, p < 0.0001). Although high-intensity training modulated the abrupt HR responses, the magnitude of the response remained unchanged at the onset of maximal forearm contraction and the resting HR significantly decreased.     

Aerobic demands of the dance simulation game

The purpose of this study was to assess the intensity and energy cost of dance simulation in relation to the American College of Sports Medicine (ACSM) recommendations on the quantity and quality of exercise for developing and maintaining cardiorespiratory fitness, and to assess its safety. Forty subjects (21 males and 19 females, age 17.5 +/- 0.7 years) had their heart rate (HR) and oxygen consumption (.VO(2)) measured during maximal treadmill exercise and during a dance simulation game at a self-selected level of difficulty. They were monitored for injuries during and after the study. The results showed a mean HR of 137 beats x min(-1) (139 beats x min(-1) for males and 136 beats x min(-1) for females) and a mean .VO(2) of 24.6 ml x kg(-1) x min(-1) (25.3 ml x kg(-1) x min(-1) for males and 23.8 ml x kg(-1) x min(-1) for females) during the dance simulation game test, with an estimated energy expenditure of 480 W (550 W for males and 410 W for females). The dance intensity only just meets the minimum ACSM guidelines, so dancer-players will need to play for extended periods to improve or maintain cardiorespiratory fitness or to lose weight. No injuries occurred during 201 hours of dance time.     

Maximal oxygen uptake and lactate metabolism are normal in chronic fatigue syndrome.

PURPOSE: Previous studies in chronic fatigue syndrome (CFS) have reported reductions in maximal oxygen uptake (VO(2max)), yet often the testing procedures have not followed accepted guidelines, and gender data have been pooled. The present study was undertaken to reevaluate exercise capacity in CFS patients by using "gold standard" maximal exercise testing methodology and stratifying results on a gender basis. METHODS: Sixteen male and 17 female CFS patients and their gender-, age-, and mass-matched sedentary controls performed incremental exercise to volitional exhaustion on a stationary cycle ergometer while selected cardiorespiratory and metabolic variables were measured. RESULTS: VO(2max) in male CFS patients was not different from control values (CFS: 40.5 +/- 6.7; controls: 43.3 +/- 8.6; mL x kg(-1) x min(-1)) and was 96.3 +/- 17.9% of the age-predicted value, indicating no functional aerobic impairment (3.7 +/- 17.9%). In female CFS patients, VO(2max) was lower than control values (CFS: 30.0 +/- 4.7; controls: 34.2 +/- 5.6; mL x kg(-1) x min(-1), P = 0.002), but controls were higher than the age-predicted value (112.6 +/- 15.4%, P = 0.008) whereas the CFS patients were 101.2 +/- 20.4%, indicating no functional aerobic impairment (-1.2 +/- 20.4%). Maximal heart rate (HR(max)) in male CFS patients was lower than their matched controls (CFS: 184 +/- 10; controls: 192 +/- 12; beats x min(-1); P = 0.016) but was 99.1 +/- 5.5% of their age-predicted value. In female CFS patients, HR(max) was not different from controls (CFS: 183 +/- 11; controls: 186 +/- 10; beats x min(-1)) and was 98.9 +/- 5.1% of the age-predicted value. The VO(2) at the lactate threshold (LT) in each gender group, whether expressed in mL x kg(-1) x min(-1) or as a percentage of VO(2max), was not different between CFS patients and controls. CONCLUSIONS: In contrast to most previous reports, the present study found that VO(2max), HR(max), and the LT in CFS patients of both genders were not different from the values expected in healthy sedentary individuals of a similar age.     

Comparison of physiological responses to open water kayaking and kayak ergometry

This study compared the physiological responses of simulated kayaking on a K1 ERGO kayak ergometer with open water paddling. Nine well-trained male kayakers (VO2peak 4.27 +/- 0.58 L x min(-1), age 24 +/- 4 yr, mass 77.3 +/- 6.4 kg, height 179.5 +/- 5.3 cm; [mean +/- SD]) performed two 4 min exercise bouts on open water (OW) and on an air braked kayak ergometer (Erg). During exercise, expired air and heart rate (HR) were continuously measured. The distance covered during OW (992 +/- 47.1 m) was highly correlated (r2 = 0.86) with the total work performed in Erg (47.64 +/- 7.67 kJ). There were no differences between trials for oxygen uptake, carbon dioxide production or estimated carbohydrate oxidation. However, during OW, minute ventilation was significantly higher at 60 and 90 s (104.2 +/- 16.4 vs. 92.6 +/- 20.4 L x min(-1) and 120.5 +/- 15.8 vs. 111.7 +/- 17.6 L x min(-1) for 60 and 90 s, respectively, p < 0.05), and HR was higher in OW during the first minute (120 +/- 20 vs. 104 +/- 19 beats x min(-1), 164 +/- 8 vs. 147 +/- 18 beats x min(-1) and 178 +/- 6 vs. 170 +/- 7 beats x min(-1) for 0, 30, and 60 s, respectively, p < 0.05). There were no differences in peak VO2 between OW and Erg (4.10 +/- 0.49 vs. 4.09 +/- 0.53 L x min(-1), respectively) nor in post-exercise blood (lactate) (6.43 +/- 1.47 vs. 6.59 +/- 0.99 mmol x L(-1), respectively). We conclude that the K1 ERGO accurately simulates the physiological demands of short-term, high-intensity kayaking.     

Physical demands of elite Rugby League referees, part two: heart rate responses and implications for training and fitness testing

The purpose of this study was to assess whether any characteristic patterns of heart rate (HR) responses could be identified in National Rugby League (NRL) referees (n= 6) during matches played in the 2001 season. The data have been plotted and discussed, in order that exercise program planning practitioners may gain improved understandings of the physiological requirements for referees. Some specific training suggestions have also been made. METHODS: The HR was recorded every five seconds throughout six competition NRL matches; using a heart rate monitor with a built-in memory. RESULTS: The specific magnitudes of referees' HR mean values varied between individuals, possibly due to specific game intensities, referee fitness, and age. All referees however exhibited similar HR response patterns; characterised by frequent (13-20 per match) large transient upward and downward shifts (>20 beats.minute(-1)). Periods of elevated HR extended for between five sec and eight min at a time, and were further characterised as a typical cyclic wave of HR elevation and recovery (ranging from 99.2+/-12.4 beats.minute(-1) to 176.5+/-11.8 beats.minute(-1) [mean +/-95% CI]), with a work to rest ratio of 2:1. Steady state HR was not achieved at any time during any match. CONCLUSIONS: The findings of the present study, taken together with a recent motion analysis, indicate that Rugby League refereeing is a highly intermittent, variable intensity activity. Significant anaerobic contribution to performance appears likely. It is suggested that training and fitness assessment of athletes should reflect their specific demands; some specific recommendations have therefore been provided.