Time course for recovery of peak aerobic power after blood donation

Peak aerobic power (VO2peak) is decreased after blood donation, but the time course for full recovery is unknown. We measured VO2peak and exercise time to fatigue before and weekly for 4 weeks after 450-ml blood donation at a blood donor clinic, to determine the time course of recovery. Twelve moderately active individuals (2 women, 10 men; 24.3 ± 5.2 years) of average aerobic fitness (based on their VO2peak relative to normative values) completed VO2peak exercise tests before donation, the day after donation, and at weekly intervals for 4 weeks after donation. VO2peak was determined by an incremental exercise test on a cycle ergometer. At baseline, mean absolute and relative VO2peak values were 4.06 ± 0.92 L·min(-1) and 46.6 ± 7.0 ml·kg(-1)·min(-1), respectively. VO2peak was significantly decreased on day 1 (3.85 ± 0.89 L·min(-1); 44.0 ± 6.5 ml·kg(-1)·min(-1)) and during week 2 (3.91 ± 0.97 L·min(-1); 44.5 ± 7.2 ml·kg(-1)·min(-1)) after blood donation (p < 0.05), and recovered at week 3 after donation. Time to fatigue and peak heart rate were not significantly affected by blood donation. We conclude that blood donation causes a significant decrease in VO2peak for between 2 and 3 weeks. The practical application of this study is that aerobic power in people of average fitness will be decreased, up to 3 weeks after donating blood. Despite this, there is no effect of blood donation on performance as measured by time to fatigue during an incremental test on a cycle ergometer.     

Effects of aging and training status on ventilatory response during incremental cycling exercise

The aim of this study was to examine the effect of aging and training status on ventilatory response during incremental cycling exercise. Eight young (24 ± 5 years) and 8 older (64 ± 3 years) competitive cyclists together with 8 young (27 ± 4 years) and 8 older (63 ± 2 years) untrained individuals underwent a continuous incremental cycling test to exhaustion to determine ventilatory threshold (VT), respiratory compensation point (RCP), and maximal oxygen uptake (VO?max). In addition, the isocapnic buffering (IB) phase was calculated together with the hypocapnic hyperventilation. Ventilatory threshold occurred at similar relative exercise intensities in all groups, whereas RCP was recorded at higher intensities in young and older cyclists compared to the untrained subjects. The IB phase, reported as the difference between VT and RCP and expressed either in absolute (ml·min?1·kg?1 VO?) or in relative terms, was greater (p < 0.01) in both young and older trained cyclists than in untrained subjects, who were also characterized by a lower exercise capacity. Isocapnic buffering was particularly small in the older untrained volunteers. Although young untrained and older trained subjects had a similar level of VO?max, older athletes exhibited a larger IB. In addition, a higher absolute but similar relative IB was observed in young vs. older cyclists, despite a higher VO?max in the former. In conclusion, the present study shows that aging is associated with a reduction of the IB phase recorded during an incremental exercise test. Moreover, endurance training induces adaptations that result in an enlargement of the IB phase independent of age. This information can be used for the characterization and monitoring of the physiological adaptations induced by endurance training.     

A 6-month supervised employer-based minimal exercise program for police officers improves fitness

The purpose of the study was to determine the effects of a 6-month supervised, job-specific moderate exercise program in police officers on body composition, cardiovascular and muscular fitness. Body weight (BW), body mass index (BMI), and cardiovascular and muscular fitness were assessed at baseline, after a 6-month supervised fitness program and at 12-month follow-up (18 months). One hundred sixty-five (n = 131 men and n = 34 women) young (mean ± SEM, 26.4 ± 1.9 years), overweight (BMI = 26.2 ± 1.2 kg·m) police officers participated. Aerobic exercise progressed from 3 d·wk, 20 minutes per session at 60% of the heart rate reserve (HRR) to 5 d·wk, 30 minutes per session at 75% of HRR at 3 months, and this level was maintained until 6 months. Muscular strength training progressed using 8 different calisthenics exercises from 3 d·wk, 2 sets of 5 repetitions using the participant's own BW to 5 d·wk, 3 sets of 15 repetitions of the participant's own BW at 3 months, and this level was maintained until 6 months. Cardiovascular and muscular fitness was measured using a 0.25-mile obstacle course incorporating various job-specific exercises and expressed as the physical abilities test (PAT) time. There was a significant reduction in BMI (-0.6 ± 0.2 kg·m, p < 0.001) and BW (-2.8 ± 2.3 kg) and reduction in PAT time (-11.9 ± 2.1%, p < 0.01) from baseline to 6 months. However, BMI (1.4 ± 1.1 kg·m, p < 0.001), BW (5.1 ± 3.0 kg, p < 0.01), and PAT time significantly increased (12.8 ± 2.2%, p < 0.01) from 6 to 18 months. There were no sex by time differences. The practical applications of this study indicate that a supervised, job-specific exercise program for police officers improves fitness and body composition after 6 months in both men and women, but continued supervision of exercise program may be necessary for maintenance of health benefits.     

Acute exercise and training alter blood lipid and lipoprotein profiles differently in overweight and obese men and women

Our purpose was to elucidate effects of acute exercise and training on blood lipids-lipoproteins, and high-sensitivity C-reactive protein (hsCRP) in overweight/obese men (n = 10) and women (n = 8); age, BMI, body fat percentage, and VO(2)max were (mean ± SEM): 45 ± 2.5 years, 31.9 ± 1.4 kg·m(-2), 41.1 ± 1.5%, and 25.2 ± 1.3 mlO(2)·kg(-1)·min(-1). Before exercise training subjects performed an acute exercise session on a treadmill (70% VO(2)max, 400 kcal energy expenditure), followed by 12 weeks of endurance exercise training (land-based or aquatic-based treadmill): 3 sessions·week(-1), progressing to 500 kcal·session(-1) during which subjects maintained accustomed dietary habits. After training, the acute exercise session was repeated. Blood samples, obtained immediately before and 24 h after acute exercise sessions, were analyzed for serum lipids, lipoproteins, and hsCRP adjusted for plasma volume shifts. Exercise training increased VO(2)max (+3.67 mlO(2)·kg(-1)·min(-1), P < 0.001) and reduced body weight (-2.7 kg, P < 0.01). Training increased high-density lipoprotein (HDL) and HDL(2b)-cholesterol (HDL-C) concentrations (+3.7 and +2.4 mg·dl(-1), P < 0.05) and particle numbers (+588 and +206 nmol·l(-1), P < 0.05) in men. In women despite no change in total HDL-C, subfractions shifted from HDL(3)-C (-3.2, P < 0.01) to HDL(2b)-C (+3.5, P < 0.05) and HDL(2a)-C (+2.2 mg·dl(-1), P < 0.05), with increased HDL(2b) particle number (+313 nmol·l(-1), P < 0.05). Training reduced LDL(3) concentration and particle number in women (-1.6 mg·dl(-1) and -16 nmol·l(-1), P < 0.05). Acute exercise reduced the total cholesterol (TC): HDL-C ratio in men (-0.16, P < 0.01) and increased hsCRP in all subjects (+0.05 mg·dl(-1), P < 0.05), regardless of training. Training did not affect acute exercise responses. Our data support the efficacy of endurance training, without dietary intervention, to elicit beneficial changes in blood lipids-lipoproteins in obese men and women.     

Effects of prolonged exercise at a similar percentage of maximal oxygen consumption in trained and untrained subjects

Six trained male cyclists and six untrained but physically active men participated in this study to test the hypothesis that the use of percentage maximal oxygen consumption (%VO2max) as a normalising independent variable is valid despite significant differences in the absolute VO2max of trained and untrained subjects. The subjects underwent an exercise test to exhaustion on a cycle ergometer to determine VO2max and lactate threshold. The subjects were grouped as trained (T) if their VO2max exceeded 60 ml.kg-1.min-1, and untrained (UT) if their VO2max was less than 50 ml.kg-1.min-1. The subjects were required to exercise on the ergometer for up to 40 min at power outputs that corresponded to approximately 50% and 70% VO2max. The allocation of each exercise session (50% or 70% VO2max) was random and each session was separated by at least 5 days. During these tests venous blood was taken 10 min before exercise (- 10 min), just prior to the commencement of exercise (0 min), after 20 min of exercise (20 min), at the end of exercise and 10 min postexercise (+ 10 min) and analysed for concentrations of cortisol, [Na+], [K+], [Cl-], glucose, free fatty acid, lactate [la-], [NH3], haemoglobin [Hb] and for packed cell volume. The oxygen consumption (VO2) and related variables were measured at two time intervals (14-15 and 34-35 min) during the prolonged exercise tests. Rectal temperature was measured throughout both exercise sessions. There was a significant interaction effect between the level of training and exercise time at 50% VO2max for heart rate (fc) and venous [la-].(ABSTRACT TRUNCATED AT 250 WORDS)     

Exercise training blunts oxidative stress in sickle cell trait carriers

The aim of this study was to analyze the effects of exercise training on oxidative stress in sickle cell trait carriers. Plasma levels of oxidative stress [advanced oxidation protein products (AOPP), protein carbonyl, malondialdehyde (MDA), and nitrotyrosine], antioxidant markers [catalase, glutathione peroxidase (GPX), and superoxide dismutase (SOD)], and nitrite and nitrate (NOx) were assessed at baseline, immediately following a maximal exercise test (T(ex)), and during recovery (T(1h), T(2h), T(24h)) in trained (T: 8 h/wk minimum) and untrained (U: no regular physical activity) sickle cell trait (SCT) carriers or control (CON) subjects (T-SCT, n = 10; U-SCT, n = 8; T-CON, n = 11; and U-CON, n = 11; age: 23.5 ± 2.2 yr). The trained subjects had higher SOD activities (7.6 ± 5.4 vs. 5.2 ± 2.1 U/ml, P = 0.016) and lower levels of AOPP (142 ± 102 vs. 177 ± 102 μM, P = 0.028) and protein carbonyl (82.1 ± 26.0 vs. 107.3 ± 30.6 nm/ml, P = 0.010) than the untrained subjects in response to exercise. In response to exercise, U-SCT had a higher level of AOPP (224 ± 130 vs. 174 ± 121 μM, P = 0.012), nitrotyrosine (127 ± 29.1 vs.70.6 ± 46.6 nM, P = 0.003), and protein carbonyl (114 ± 34.0 vs. 86.9 ± 26.8 nm/ml, P = 0.006) compared with T-SCT. T-SCT had a higher SOD activity (8.50 ± 7.2 vs. 4.30 ± 2.5 U/ml, P = 0.002) and NOx (28.8 ± 11.4 vs. 14.6 ± 7.0 μmol·l(-1)·min(-1), P = 0.003) in response to exercise than U-SCT. Our data indicate that the overall oxidative stress and nitric oxide response is improved in exercise-trained SCT carriers compared with their untrained counterparts. These results suggest that physical activity could be a viable method of controlling the oxidative stress. This could have a beneficial impact because of its involvement in endothelial dysfunction and subsequent vascular impairment in hemoglobin S carriers.     

A protocol of intermittent exercise (shuttle runs) to train young basketball players

The purpose of this study was to set up a protocol of intermittent exercise to train young basketball players. Twenty-one players were asked to complete (a) an incremental test to determine maximal oxygen uptake (VO2max), the speed at the ventilatory threshold (vthr) and the energy cost of "linear" running (Cr) and (b) an intermittent test composed of 10 shuttle runs of 10-second duration and 30-seconds of recovery (total duration: about 6 minutes). The exercise intensity (the running speed, vi) was set at 130% of vthr. During the intermittent tests, oxygen uptake (VO2) and blood lactate concentration (Lab) were measured. The average pretraining VO2 calculated for a single bout (131 ± 9 ml · min(-1) kg(-1)) was about 2.4 times greater than the subjects' measured VO2max (54.7 ± 4.6 ml · min(-1) · kg(-1)). The net energy cost of running (9.2 ± 0.9 J · m(-1) · kg(-1)) was about 2.4 times higher than that measured at constant "linear" speed (3.9 ± 0.3 J · m(-1) · kg(-1)). The intermittent test was repeated after 7 weeks of training: 9 subjects (control group [CG]) maintained their traditional training schedule, whereas for 12 subjects (experimental group [EG]) part of the training was replaced by intermittent exercise (the same shuttle test as described above). After training, the VO2 measured during the intermittent test was significantly reduced (p < 0.05) in both groups (-10.9% in EG and - 4.6 in CG %), whereas Lab decreased significantly only for EG (-31.5%). These data suggest that this training protocol is effective in reducing lactate accumulation in young basketball players.     

Cardiorespiratory and metabolic alterations during exercise and passive recovery after three modes of exercise

The objective of this study was to investigate the potential variations in cardiorespiratory and metabolic parameters and running performance among 3 modes of exercise of the same duration, namely, intermittent running with active recovery (AR) or passive recovery (PR) and continuous running (CR) and whether these variations could affect passive recovery time (PRT). Fifteen male physical education students with a subspecialty in soccer were studied (mean age 22.3 ± 2.5 years, training experience 12.3 ± 2.5 years) in the middle of the playing season. The results showed that during exercise, the highest heart rate (HR) and VO2 values were observed in CR, whereas the lowest values in PR followed by AR. Blood lactate (BLa) concentration was higher in PR by 38% compared to that in AR (p < 0.05). The exercise duration was similar between PR and AR tests and longer than in CR. With regard to PRT, the highest HR (186 ± 9 b · min(-1)), VO2 (55.5 ± 5.2 ml · kg(-1) · min(-1)), and BLa (5.1 ± 1.7 mmol · L(-1)) values were found in CR. No differences in HR and VO2 between PR and AR were detected. However, despite the differences in BLa concentration between AR and PR during exercise, the PRT BLa values between these 2 exercise modes were not different. Among the 3 running protocols, only CR appeared to have fully challenged the cardiorespiratory system inducing maximal HR and VO2 responses during exercise and high BLa values in PRT, yet these responses were not associated with better exercise performance compared to intermittent running. Therefore, intermittent exercise, regardless of implementing passive or active interval, might be the preferable exercise mode particularly in activities extended over 30 minutes.     

Endothelial function in highly endurance-trained men: effects of acute exercise

Exercise training reverses endothelial dysfunction, but the effect in young, healthy subjects is less clear. We determined the influence of maximal oxygen uptake (VO2max) and a single bout of high-intensity exercise on flow-mediated dilatation (FMD), brachial artery diameter, peak blood flow, nitric oxide (NO) bioavailability, and antioxidant status in highly endurance-trained men and their sedentary counterparts. Ten men athletes (mean +/- SEM age 23.5 +/- 0.9 years, height 182.6 +/- 2.4 cm, weight 72.5 +/- 2.4 kg, VO2max 75.9 +/- 0.8 mL.kg.min) and seven healthy controls (age 25.4 +/- 1.2 years, height 183.9 +/- 3.74 cm, weight 92.8 +/- 3.9 kg, VO2max 47.7 +/- 1.7 mL.kg.min) took part in the study. FMD, brachial artery diameter, and peak blood flow were measured using echo-Doppler before, 1 hour, 24 hours, and 48 hours after a single bout of interval running for 5 x 5 minutes at 90% of maximal heart rate. NO bioavailability and antioxidant status in blood were measured at all time points. Maximal arterial diameter and peak flow were 10-15% (P < 0.02) and 28-35% (P < 0.02) larger, respectively, in athletes vs. controls at all time points, and similar FMD were observed, apart from a transient decay of FMD in athletes 1 hour post exercise. NO bioavailability increased significantly after exercise in both groups and decreased to baseline levels after 24 hours in controls but remained increased 80% and 93% above baseline 24 and 48 hours post exercise in athletes. Antioxidant status was equal in the two groups at baseline and increased by approximately 10% 1 hour post exercise, an effect that lasted for 24 hours. Athletes had larger arterial diameter but similar FMD as untrained subjects, i.e., athletes had larger capacity for blood transport compared with their untrained counterparts. The observed FMD, bioavailability of NO, and antioxidant status in blood were highly dependent on the time elapsed after the exercise session.     

Endurance training decreases plasma glucose turnover and oxidation during moderate-intensity exercise in men

To assess the effects of endurance training on plasma glucose kinetics during moderate-intensity exercise in men, seven men were studied before and after 12 wk of strenuous exercise training (3 days/wk running, 3 days/wk cycling). After priming of the glucose and bicarbonate pools, [U-13C] glucose was infused continuously during 2 h of cycle ergometer exercise at 60% of pretraining peak O2 uptake (VO2) to determine glucose turnover and oxidation. Training increased cycle ergometer peak VO2 by 23% and decreased the respiratory exchange ratio during the final 30 min of exercise from 0.89 +/- 0.01 to 0.85 +/- 0.01 (SE) (P less than 0.001). Plasma glucose turnover during exercise decreased from 44.6 +/- 3.5 mumol.kg fat-free mass (FFM)-1.min-1 before training to 31.5 +/- 4.3 after training (P less than 0.001), whereas plasma glucose clearance (i.e., rate of disappearance/plasma glucose concentration) fell from 9.5 +/- 0.6 to 6.4 +/- 0.8 ml.kg FFM-1.min-1 (P less than 0.001). Oxidation of plasma-derived glucose, which accounted for approximately 90% of plasma glucose disappearance in both the untrained and trained states, decreased from 41.1 +/- 3.4 mumol.kg FFM-1.min-1 before training to 27.7 +/- 4.8 after training (P less than 0.001). This decrease could account for roughly one-half of the total reduction in the amount of carbohydrate utilized during the final 30 min of exercise in the trained compared with the untrained state.     

Physical fitness of an industrial fire department vs. a municipal fire department

Both industrial and municipal firefighters need to maintain high levels of physical fitness and minimize cardiovascular risk factors. The nature of firefighter responsibilities in industrial and municipal settings may vary, affecting the ability to sustain high levels of physical fitness. We compared the working conditions, physical fitness, and exercise training practices of an industrial fire department (n = 17) to those of a nearby municipal fire department (n = 55). After informed consent, aerobic capacity, muscular strength, muscular endurance, body composition, flexibility, blood lipid concentrations, and blood pressure levels were measured. Exercise training practices and related factors were assessed using a questionnaire. Despite programmatic differences, these departments demonstrated similar, relatively high degrees of physical fitness and similar blood lipid concentrations, blood pressure levels, and cardiac risk factors. It is recommended that fire departments involve appropriately trained staff, schedule on-duty times for exercise, offer well-equipped exercise facilities, and follow National Strength and Conditioning Association (NSCA) and American College of Sports Medicine (ACSM) guidelines for exercise conditioning in order to maintain a high degree of physical fitness.     

Oxygen uptake kinetics and time to exhaustion in cycling and running: a comparison between trained and untrained subjects

The objective of the present study was to compare pulmonary gas exchange kinetics (VO2 kinetics) and time to exhaustion (Tlim) between trained and untrained individuals during severe exercise performed on a cycle ergometer and treadmill. Eleven untrained males in running (UR) and cycling (UC), nine endurance cyclists (EC), and seven endurance runners (ER) were submitted to the following tests on separate days: (i) incremental test for determination of maximal oxygen uptake (VO2max) and the intensity associated with the achievement of VO2max (IVO2max) on a mechanical braked cycle ergometer (EC and UC) and on a treadmill (ER and UR); (ii) all-out exercise bout performed at IVO2max to determine the time to exhaustion at IVO2max (Tlim) and the time constant of oxygen uptake kinetics (tau). The tau was significantly faster in trained group, both in cycling (EC = 28.2 +/- 4.7s; UC = 63.8 +/- 25.0s) and in running (ER = 28.5 +/- 8.5s; UR = 59.3 +/- 12.0s). Tlim of untrained was significantly lower in cycling (EC = 384.4 +/- 66.6s vs. UC; 311.1 +/- 105.7 s) and higher in running (ER = 309.2 +/- 176.6 s vs. UR = 439.8 +/- 104.2 s). We conclude that the VO2 kinetic response at the onset of severe exercise, carried out at the same relative intensity is sensitive to endurance training, irrespective of the exercise type. The endurance training seems to differently influence Tlim during exercise at IVO2max in running and cycling.     

Time course of the effects of static stretching on cycling economy

Stretching has been implemented as part of the warm-up before physical events and widely thought to promote increased sport performance and decreased injury risk. However, recent research has concluded that static stretching before many exercises inhibits acute power, strength, and sprinting performance. There is little research examining the time course of these effects on moderate intensity cycling. The purpose of this study was to examine the time course of static stretching on cycling economy. The subjects consisted of 5 men and 5 women highly trained endurance cyclists. The first of 3 visits was baseline testing of their cycling VO2max. The second and third visits were either stretching or no stretching before a 30-minute stationary ride at 65% of their VO2max. The stretching condition consisted of four 30-second repetitions of 5 stretches with an average total stretching time of 16 minutes. VO2 demonstrated a significant condition by time interaction with the 5-minute time point being significantly less in the nonstretching condition (32.66 ± 5.35 ml·kg(-1)·min(-1)) than stretching (34.39 ± 5.39 ml·kg(-1)·min(-1)). No other time points were different. Our results demonstrate that static stretching yielded an acute increase in submaximal VO2; therefore, coaches and highly trained endurance cyclists should exclude static stretching immediately before moderate intensity cycling because it reduces acute cycling economy.     

Exercise intensity: effect on postexercise O2 uptake in trained and untrained women

Despite many reports of long-lasting elevation of metabolism after exercise, little is known regarding the effects of exercise intensity and duration on this phenomenon. This study examined the effect of a constant duration (30 min) of cycle ergometer exercise at varied intensity levels [50 and 70% of maximal O2 consumption (VO2max)] on 3-h recovery of oxygen uptake (VO2). VO2 and respiratory exchange ratios were measured by open-circuit spirometry in five trained female cyclists (age 25 +/- 1.7 yr) and five untrained females (age 27 +/- 0.8 yr). Postexercise VO2 measured at intervals for 3 h after exercise was greater (P less than 0.01) after exercise at 50% VO2max in trained (0.40 +/- 0.01 l/min) and untrained subjects (0.39 +/- 0.01 l/min) than after 70% VO2max in (0.31 +/- 0.02 l/min) and untrained subjects (0.29 +/- 0.02 l/min). The lower respiratory exchange ratio values (P less than 0.01) after 50% VO2max in trained (0.78 +/- 0.01) and untrained subjects (0.80 +/- 0.01) compared with 70% VO2max in trained (0.81 +/- 0.01) and untrained subjects (0.83 +/- 0.01) suggest that an increase in fat metabolism may be implicated in the long-term elevation of metabolism after exercise. This was supported by the greater estimated fatty acid oxidation (P less than 0.05) after 50% VO2max in trained (147 +/- 4 mg/min) and untrained subjects (133 +/- 9 mg/min) compared with 70% VO2max in trained (101 +/- 6 mg/min) and untrained subjects (85 +/- 7 mg/min).     

The effect of training on responses of beta-endorphin and other pituitary hormones to insulin-induced hypoglycemia

We studied whether the previously reported intensified beta-endorphin response to exercise after training might result from a training-induced general increase in anterior pituitary secretory capacity. Identical hypoglycemia was induced by insulin infusion in 7 untrained (VO2max 49 +/- 4 ml X (kg X min)-1, mean and SE) and 8 physically trained (VO2max 65 +/- 4 ml X (kg X min)-1) subjects. In response to hypoglycemia, levels of beta-endorphin and prolactin immunoreactivity in serum increased similarly in trained (from 41 +/- 2 pg X ml-1 and 6 +/- 1 pg X ml-1 before hypoglycemia to 103 +/- 11 pg X ml-1 and 43 +/- 9 pg X ml-1 during recovery, P less than 0.05) and untrained (from 35 +/- 7 pg X ml-1 and 7 +/- 2 pg X ml-1 to 113 +/- 18 pg X ml-1 and 31 +/- 8 pg X ml-1, P less than 0.05) subjects. Growth hormone (GH) was higher 90 min after glucose nadir in trained (61 +/- 13 mU X l-1) than in untrained (25 +/- 6 mU X l-1) subjects (P less than 0.05). Levels of thyrotropin (TSH) changed in neither of the groups. It is concluded that, in contrast to what has been formerly proposed, training does not result in a general increase in secretory capacity of the anterior pituitary gland. TSH responds to hypoglycemia neither in trained nor in untrained subjects. Finally, differences in beta-endorphin responses to exercise between trained and untrained subjects cannot be ascribed to differences in responsiveness to hypoglycemia.     

Metabolic syndrome is inversely related to cardiorespiratory fitness in male career firefighters

Cardiovascular disease (CVD) accounts for 45% of on-duty fatalities among firefighters, occurring primarily in firefighters with excess CVD risk factors in patterns resembling the metabolic syndrome (MetSyn). Additionally, firefighters have a high prevalence of obesity and sedentary behavior suggesting that MetSyn is also common. Therefore, we assessed the prevalence of MetSyn in firefighters and its association with cardiorespiratory fitness (CRF) in a cross-sectional study of 957 male career firefighters. The CRF was measured by maximal exercise tolerance testing (standard metabolic equivalent [METS]). The MetSyn was defined according to modified criteria from the Joint Scientific Statement. Group differences were compared using χ-test and logistic regression. The prevalence of MetSyn was 28.3%. Firefighters in the lowest fitness category (METS ≤ 10) had a nearly 10-fold higher prevalence of MetSyn (51.2%) compared with colleagues in the highest fitness category (METS > 14) (MetSyn prevalence 5.2%) (p value < 0.0001, adjusted for age). In multivariate regression models, every 1-unit increase in METS decreased the odds of having the MetSyn by 31% (odds ratio 0.69 [95% confidence interval 0.63-0.76] [age adjusted]), whereas age had no significant effect after adjusting for CRF. We found a high prevalence of the MetSyn in this group of career emergency responders expected to be more active, fit, and relatively younger than the general population. Moreover, there is a highly significant inverse, dose-response association with CRF. Firefighters should be given strong incentives to improve their fitness, which would decrease prevalent MetSyn, a likely precursor of on-duty CVD events and contributor to CVD burden in this population.     

Evaluation of the American College of Sports Medicine submaximal treadmill running test for predicting VO2max

The purpose of this study was to assess the validity of the American College of Sports Medicine's (ACSM's) submaximal treadmill running test in predicting VO2max. Twenty-one moderately well-trained men aged 18-34 years performed 1 maximal treadmill test to determine maximal oxygen uptake (M VO2max) and 2 submaximal treadmill tests using 4 stages of continuous submaximal exercise. Estimated VO2max was predicted by extrapolation to age-predicted maximal heart rate (HRmax) and calculated in 2 ways: using data from all submaximal stages between 110 b·min(-1) and 85% HRmax (P VO2max-All), and using data from the last 2 stages only (P VO2max-2). The measured VO2max was overestimated by 3% on average for the group but was not significantly different to predicted VO2max (1-way analysis of variance [ANOVA] p = 0.695; M VO2max = 53.01 ± 5.38; P VO2max-All = 54.27 ± 7.16; P VO2max-2 = 54.99 ± 7.69 ml·kg(-1)·min(-1)), although M VO2max was not overestimated in all the participants--it was underestimated in 30% of observations. Pearson's correlation, standard error of estimate (SEE), and total error (E) between measured and predicted VO2max were r = 0.646, 4.35, 4.08 ml·kg(-1)·min(-1) (P VO2max-All) and r = 0.642, 4.21, 3.98 ml·kg(-1)·min(-1) (P VO2max-2) indicating that the accuracy in prediction (error) was very similar whether using P VO2max-All or P VO2max-2, with up to 70% of the participants predicted scores within 1 SEE (～4 ml·kg(-1)·min(-1)) of M VO2max. In conclusion, the ACSM equation provides a reasonably good estimation of VO2max with no difference in predictive accuracy between P VO2max-2 and P VO2max-All, and hence, either approach may be equally useful in tracking an individual's aerobic fitness over time. However, if a precise knowledge of VO2max is required, then it is recommended that this be measured directly.     

Sweating responses and the muscle metaboreflex under mildly hyperthermic conditions in sprinters and distance runners

To investigate the effects of different training methods on nonthermal sweating during activation of the muscle metaboreflex, we compared sweating responses during postexercise muscle occlusion in endurance runners, sprinters, and untrained men under mild hyperthermia (ambient temperature, 35°C; relative humidity, 50%). Ten endurance runners, nine sprinters, and ten untrained men (maximal oxygen uptakes: 57.5 ± 1.5, 49.3 ± 1.5, and 36.6 ± 1.6 ml·kg(-1)·min(-1), respectively; P < 0.05) performed an isometric handgrip exercise at 40% maximal voluntary contraction for 2 min, and then a pressure of 280 mmHg was applied to the forearm to occlude blood circulation for 2 min. The Δ change in mean arterial blood pressure between the resting level and the occlusion was significantly higher in sprinters than in untrained men (32.2 ± 4.4 vs. 17.3 ± 2.6 mmHg, respectively; P < 0.05); however, no difference was observed between distance runners and untrained men. The Δ mean sweating rate (averaged value of the forehead, chest, forearm, and thigh) during the occlusion was significantly higher in distance runners than in sprinters and untrained men (0.38 ± 0.07, 0.19 ± 0.03, and 0.11 ± 0.04 mg·cm(-2)·min(-1), respectively; P < 0.05) and did not differ between sprinters and untrained men. Our results suggest that the specificity of training modalities influences the sweating response during activation of the muscle metaboreflex. In addition, these results imply that a greater activation of the muscle metaboreflex does not cause a greater sweating response in sprinters.