Influence of exercise intensity on systemic oxidative stress and antioxidant capacity

The aim of the current study was to examine the influence of exercise intensity on systemic oxidative stress (OS) and endogenous antioxidant capacity. Non‐smoking, sedentary healthy adult males (n = 14) participated in two exercise sessions using an electronically braked cycle ergometer. The first session consisted of a graded exercise test to determine maximal power output and oxygen consumption (VO_2max). One week later, participants undertook 5‐min cycling bouts at 40%, 55%, 70%, 85% and 100% of VO_2max, with passive 12‐min rest between stages. Measures of systemic OS reactive oxygen metabolites (dROM), biological antioxidant potential (BAP), heart rate (HR), VO₂, blood lactate and rating of perceived exertion were assessed at rest and immediately following each exercise stage. Significant (P<0·05) differences between exercise bouts were examined via repeated measures ANOVA and post hoc pairwise comparisons with Bonferroni correction. Increasing exercise intensity significantly augmented HR (P<0·001), VO₂ (P<0·001), blood lactate (P<0·001) and perceived exertion (P<0·001) with no significant effect on dROM levels compared with resting values. In contrast, increasing exercise intensity resulted in significantly (P<0·01) greater BAP at 70% (2427 ± 106), 85% (2625 ± 121) and 100% (2651 ± 92) of VO_2max compared with resting levels (2105 ± 57 μmol Fe²⁺/L). The current results indicate that brief, moderate‐to‐high‐intensity exercise significantly elevates endogenous antioxidant defences, possibly to counteract increased levels of exercise‐induced reactive oxygen species. Regular moderate‐to‐high‐intensity exercise may protect against chronic OS associated diseases via activation, and subsequent upregulation of the endogenous antioxidant defence system.     

Validation of a single‐stage fixed‐rate step test for the prediction of maximal oxygen uptake in healthy adults

Healthcare professionals with limited access to ergospirometry remain in need of valid and simple submaximal exercise tests to predict maximal oxygen uptake (VO_2max). Despite previous validation studies concerning fixed‐rate step tests, accurate equations for the estimation of VO_2max remain to be formulated from a large sample of healthy adults between age 18–75 years (n > 100). The aim of this study was to develop a valid equation to estimate VO_2max from a fixed‐rate step test in a larger sample of healthy adults. A maximal ergospirometry test, with assessment of cardiopulmonary parameters and VO_2max, and a 5‐min fixed‐rate single‐stage step test were executed in 112 healthy adults (age 18–75 years). During the step test and subsequent recovery, heart rate was monitored continuously. By linear regression analysis, an equation to predict VO_2max from the step test was formulated. This equation was assessed for level of agreement by displaying Bland–Altman plots and calculation of intraclass correlations with measured VO_2max. Validity further was assessed by employing a Jackknife procedure. The linear regression analysis generated the following equation to predict VO_2max (l min^?1) from the step test: 0·054(BMI)+0·612(gender)+3·359(body height in m)+0·019(fitness index)?0·012(HRmax)?0·011(age)?3·475. This equation explained 78% of the variance in measured VO_2max (F = 66·15, P<0·001). The level of agreement and intraclass correlation was high (ICC = 0·94, P<0·001) between measured and predicted VO_2max. From this study, a valid fixed‐rate single‐stage step test equation has been developed to estimate VO_2max in healthy adults. This tool could be employed by healthcare professionals with limited access to ergospirometry.     

Cardiac power output and its response to exercise in athletes and non‐athletes

Cardiac power output (CPO) is an integrative measure of overall cardiac function as it accounts for both, flow‐ and pressure‐generating capacities of the heart. The purpose of the present study was twofold: (i) to assess cardiac power output and its response to exercise in athletes and non‐athletes and (ii) to determine the relationship between cardiac power output and reserve and selected measures of cardiac function and structure. Twenty male athletes and 32 age‐ and gender‐matched healthy sedentary controls participated in this study. CPO was calculated as the product of cardiac output and mean arterial pressure, expressed in watts. Measures of hemodynamic status, cardiac structure and pumping capability were assessed by echocardiography. CPO was assessed at rest and after peak bicycle exercise. At rest, the two groups had similar values of cardiac power output (1·08 ± 0·2 W versus 1·1 ± 0·24 W, P>0·05), but the athletes demonstrated lower systolic blood pressure (109·5 ± 6·2 mmHg versus 117·2 ± 8·2 mmHg, P<0·05) and thicker posterior wall of the left ventricle (9·8 ± 1 mm versus 9 ± 1·1 mm, P<0·05). Peak CPO was higher in athletes (5·87 ± 0·75 W versus 5·4 ± 0·69 W, P<0·05) as was cardiac reserve (4·92 ± 0·66 W versus 4·26 ± 0·61 W, P<0·05), respectively. Peak exercise CPO and reserve were only moderately correlated with end‐diastolic volume (r = 0·54; r = 0·46, P<0·05) and end‐diastolic left ventricular internal diameter (r = 0·48; r = 0·42, P<0·05), respectively. Athletes demonstrated greater maximal cardiac pumping capability and reserve than non‐athletes. The study provides new evidence that resting measures of cardiac structure and function need to be considered with caution in interpretation of maximal cardiac performance.     

Microcirculation of skeletal muscle adapts differently to a resistive exercise intervention with and without superimposed whole‐body vibrations

Whole‐body vibration (WBV) training is commonly practiced and may enhance peripheral blood flow. Here, we investigated muscle morphology and acute microcirculatory responses before and after a 6‐week resistive exercise training intervention without (RE) or with (RVE) simultaneous whole‐body vibrations (20 Hz, 6 mm peak‐to‐peak amplitude) in 26 healthy men in a randomized, controlled parallel‐design study. Total haemoglobin (tHb) and tissue oxygenation index (TOI) were measured in gastrocnemius muscle (GM) with near‐infrared spectroscopy (NIRS). Whole‐body oxygen consumption (VO₂) was measured via spirometry, and skeletal muscle morphology was determined in soleus (SOL) muscle biopsies. Our data reveal that exercise‐induced muscle deoxygenation both before and after 6 weeks training was similar in RE and RVE (P = 0·76), although VO₂ was 20% higher in the RVE group (P<0·001). The RVE group showed a 14%‐point increase in reactive hyperaemia (P = 0·007) and a 27% increase in blood volume (P<0·01) in GM after 6 weeks of training. The number of capillaries around fibres was increased by 15% after 6 weeks training in both groups (P<0·001) with no specific effect of superimposed WBV (P = 0·61). Neither of the training regimens induced fibre hypertrophy in SOL. The present findings suggest an increased blood volume and vasodilator response in GM as an adaptation to long‐term RVE, which was not observed after RE alone. We conclude that RVE training enhances vasodilation of small arterioles and possibly capillaries. This effect might be advantageous for muscle thermoregulation and the delivery of oxygen and nutrients to exercising muscle and removal of carbon dioxide and metabolites.     

A programme based on repeated hypoxia–hyperoxia exposure and light exercise enhances performance in athletes with overtraining syndrome: a pilot study

Overtraining syndrome (OTS) is a major concern among endurance athletes and is a leading cause in preventing them to perform for long periods. Intermittent exposure to hypoxia has been shown to be an effective way of improving performance without exercising. Aim of this pilot study was to evaluate intermittent hypoxia–hyperoxia training combined with light exercise as an intervention to facilitate athletes with OTS to restore their usual performance level. Thirty-four track and field athletes were recruited: 15 athletes with OTS volunteered to participate and undertook a conditioning programme consisting of repeated exposures to hypoxia (O₂ at 10%) and hyperoxia (O₂ at 30%) (6–8 cycles, total time 45 min–1 h), three times a week, delivered 1·5–2 h after a low-intensity exercise session (2 bouts of 30 min, running at 50% of VO_2max with 10 min rest between bouts) over 4 weeks. Nineteen healthy track and field athletes volunteered to participate as a control group and followed their usual training schedule. Measurements before and after the intervention included exercise capacity, analysis of heart rate variability and hematological parameters. In athletes with OTS, a 4-week light exercise combined with intermittent hypoxia–hyperoxia training improved exercise performance (191·9 ± 26·9 W versus 170·8 ± 44·8 W in exercise capacity test, P = 0·01). Heart rate variability analysis revealed an improved sympatho-parasympathetic index (low frequency/high frequency ratio, 8·01 ± 7·51 before and 1·45 ± 1·71 after, P = 0·007). Hematological parameters were unchanged. Our pilot study showed that intermittent hypoxia–hyperoxia training and low-intensity exercise can facilitate functional recovery among athletes with OTS in a relatively short time.     

Assessment of the influence of age on the rate of heart rate decline after maximal exercise in non‐athletic adult males

This study investigated the influence of age on heart rate (HR) decline after exercise in non‐athletic adult males. One hundred and fourteen adult males (66 young, 25 ± 6·26 years; 48 old, 53 ± 8·54 years) participated in the study. Subjects performed maximum‐effort ergometer exercise in incremental stages. HR was measured at rest and continuously monitored during and after exercise. Maximum oxygen uptake (VO_2max) was measured during the exercise using respiratory gas analyser. Body mass index (BMI) was computed from weight and height measurements, while rating of perceived exertion (RPE) was obtained immediately after the exercise. Results indicated age differences in the rate of HR decline with the young presenting significantly higher %HR decline (P<0·001) than old adults at both levels of recovery. When linearly correlated with age, the rate of HR decline in 1 and 3 min indicated variances of (52%,56%) in young adults, and (54%,49%) in the old adults. After controlling for VO_2max, resting HR, BMI and RPE, the influence of age on rate of HR decline in the two phases of recovery disappeared in young. In the older adult group, it reduced greatly in the 1‐min recovery (r² = 25%; P = 0·001) and disappeared in the 3‐min recovery. Pattern of HR recovery did not differ between the two age groups while age threshold was observed in HR recovery in 1 min. In summary, the influence that age appeared to have on the rate of HR decline could not hold when factors affecting HR recovery were taken into account.     

A comparison of postexercise shear rate patterns following different intensities and durations of running in healthy men

Purpose: We tested the hypothesis that high‐intensity exercise would elicit the greatest alterations in postexercise shear rate (SR) patterns when compared to moderate intensity exercise, and moderate duration exercise would produce similar postexercise SR patterns as long‐duration exercise. Methods: On separate days, ten healthy men completed three acute treadmill exercise sessions at different intensities and/or durations. Sessions were 80% VO_2peak for 30 min (HIGH), 50% VO_2peak for 30 min (MOD) and 50% VO_2peak for 60 min (MOD_L). SR in the brachial artery was assessed at baseline, immediately postexercise, 1 and 2 h postexercise using Doppler ultrasound. Results: Oscillatory and retrograde SR decreased immediately following all exercise sessions (P<0·01) and returned to baseline at 1 h postexercise; however, there were no differences between sessions (P>0·08). Antegrade and mean SR were elevated immediately following all exercise sessions (P<0·01), and the greatest elevations were observed following the HIGH session (P<0·05). Antegrade and mean SR declined below baseline values at 1 h (P<0·05) and 2 h (P<0·05) after the MOD_L session and 2 h following the HIGH session (P<0·05). Conclusion: Antegrade and mean SR immediately following running exercise are dependent upon exercise intensity. Reductions in oscillatory and retrograde SR after treadmill running are not dependent on exercise intensity or duration and appear to last <1 h. Collectively, SR profiles following exercise are differentially altered based on the dose of exercise performed.     

The effect of different exercise‐testing protocols on atrial natriuretic peptide

The aim of this study was to examine and to compare alterations in the secretion of atrial natriuretic peptide (ANP) during different exercise‐testing protocols in moderately trained men. Fifteen healthy male physical education students were studied (mean age 22·3 ± 2·5 years, training experience 12·3 ± 2·5 years, height 1·80 ± 0·06 m, weight 77·4 ± 8·2 kg). Participants performed an initial graded maximal exercise testing on a treadmill for the determination of VO_2max (duration 7·45–9·3 min and VO_2max 55·05 ± 3·13 ml kg^?1 min^?1) and were examined with active recovery (AR), passive recovery (PR) and continuous running (CR) in random order. Blood samples for plasma ANP concentration were taken at rest (baseline measurement), immediately after the end of exercise as well as after 30 min in passive recovery time (PRT). The plasma ANP concentration was determined by radioimmunoassay (RIA). The results showed that ANP plasma values increased significantly from the rest period to maximal values. In the short‐term graded maximal exercise testing the ANP plasma values increased by 56·2% (44·8 ± 10·4 pg ml^?1 versus 102·3 ± 31·3 pg ml^?1, P<0.001) and in the CR testing the ANP levels increased by 29·2% (44·8 ± 10·4 pg ml^?1 versus 63·3 ± 19·8 pg ml^?1, P<0.001) compared to the baseline measurement. Moreover, the values of ANP decreased significantly (range 46·4–51·2%, P<0.001) in PRT after the end of the four different exercise modes. However, no significant difference was evident when ANP values at rest and after AR and PR were compared. It is concluded that the exercise testing protocol may affect the plasma ANP concentrations. Particularly, short‐term maximal exercise significantly increases ANP values, while the intermittent exercise form of active and passive recovery decreases ANP concentrations.     

Plasma oxidative stress is induced by single‐sprint anaerobic exercise in young cigarette smokers

Cigarette smoking increases oxidative stress, which is a risk factor for several diseases. Smoking has also been reported to enhance plasma oxidative stress during strenuous exercise. However, no prior study has examined the changes in plasma oxidative stress after single‐sprint anaerobic exercise in cigarette smokers. The purpose of this study was to investigate these changes in young cigarette smokers by measuring reactive oxygen species generation and total antioxidant content. Participants were 15 male smokers (mean age: 25·9 ± 2·9 years) and 18 male non‐smokers (mean age: 24·2 ± 4·3 years). Hydroperoxide concentration and biological antioxidant potential (BAP) in plasma were measured at baseline and after the Wingate anaerobic test. A significant interaction between group and time was observed for plasma hydroperoxide concentration (P = 0·037). Plasma hydroperoxide concentration was significantly increased after exercise in both smokers and non‐smokers (P = 0·001 and <0·001, respectively). However, no significant interaction was observed between groups by time on plasma BAP (P = 0·574), and a main effect of time was observed (P<0·001). Plasma BAP was significantly increased after exercise in both groups (both, P<0·001). These findings indicate that plasma oxidative stress is higher in cigarette smokers than in non‐smokers after single‐sprint anaerobic exercise, which may increase the risk of oxidative damage.     

Metabolic cost of locomotion during treadmill walking with blood flow restriction

We explored whether interval walking with blood flow restriction (BFR) increases net metabolic cost of locomotion in healthy young men at their optimal walking speed. We also determined whether decreased walking economy resulting from BFR might be accompanied by an increase in ventilation relative to VO₂ and VCO₂. Finally, we examined possible relationships between the changes in ratings of perceived exertion (RPE) and those obtained in minute ventilation (V_E) during walking with BFR. Eighteen healthy men (age: 22·5 ± 3·4 years) performed graded treadmill exercise to assess VO_2max. In a randomized fashion, participants also performed five bouts of 3‐min treadmill exercise with and without BFR at their optimal walking speed. Walking with BFR elicited an overall increase in net VO₂ (10·4%) compared with that seen in the non‐BFR condition (P<0·05). The participants also demonstrated greater V_E and V_E/VO₂ values while walking with BFR (P<0·05). Conversely, V_E/VCO₂ was similar between conditions at each walking bout. We found no significant correlation between the changes in V_E and RPE induced by walking with BFR (r = 0·38, P>0·05). Our results indicate that (i) BFR decreases net walking economy in healthy young men, even at their optimal walking speed; (ii) heightened ventilatory drive may explain a small proportion of BFR effects on walking economy; and (iii) the ventilatory responses to BFR walking may be largely independent of changes in perceived exertion and are likely matched to the flux of CO₂ between muscles and respiratory centres.     

Cardiopulmonary exercise testing for evaluation of a randomized exercise training intervention following aortic valve replacement

Aortic valve surgery is the definitive treatment for aortic stenosis (AS). No specific recommendation is available on how exercise training should be conducted and evaluated after aortic valve replacement (AVR). This study aimed to examine the effect of aerobic exercise training on exercise capacity following AVR. In addition to our primary outcome variable, peak oxygen uptake (peakVO₂), the effect on submaximal cardiopulmonary variables including oxygen uptake kinetics (tau), oxygen uptake efficiency slope (OUES) and ventilatory efficiency (VE/VCO₂ slope) was evaluated. Following AVR due to AS, 12 patients were randomized to either a group receiving 12 weeks of supervised aerobic exercise training (EX) or a control group (CON). Exercise capacity was assessed by a maximal cardiopulmonary exercise test (CPET). There was a significant increase in peak load (+28%, P = 0·031) and in peakVO₂ (+23%, P = 0·031) in EX, corresponding to an increase in achieved percentage of predicted peakVO₂ from 88 to 104% (P = 0·031). For submaximal variables, there were only non‐statistically significant trends in improvement between CPETs in EX. In CON, there were no significant differences in any maximal or submaximal variable between CPETs. We conclude that 12 weeks of supervised aerobic exercise training induces significant adaptations in cardiopulmonary function following AVR, especially in regard to maximal variables including peakVO₂. In addition, we provide novel data on the effect on several submaximal variables following exercise training in this group of patients.     

A comparison of dynamic contrast‐enhanced CT and MR imaging‐derived measurements in patients with cervical cancer

This work is to compare the kinetic parameters derived from the DCE‐CT and ‐MR data of a group of 37 patients with cervical cancer. The modified Tofts model and the reference tissue method were applied to estimate kinetic parameters. In the MR kinetic analyses using the modified Tofts model for each patient data set, both the arterial input function (AIF) measured from DCE‐MR images and a population‐averaged AIF from the literature were applied to the analyses, while the measured AIF was used for the CT kinetic analysis. The kinetic parameters obtained from both modalities were compared. Significant moderate correlations were found in modified Tofts parameters [volume transfer constant(K^trans) and rate constant (k_ep)] between CT and MR analysis for MR with the measured AIFs (R = 0·45, P<0·01 and R = 0·40, P<0·01 in high‐K^trans region; R = 0·38, P<0·01 and R = 0·80, P<0·01 in low‐K^trans region) as well as with the population‐averaged AIF (R = 0·59, P<0·01 and R = 0·62, P<0·01 in high‐K^trans region; R = 0·50, P<0·01 and R = 0·63, P<0·01 in low‐K^trans region), respectively. In addition, from the Bland–Altman plot analysis, it was found that the systematic biases (the mean difference) between the modalities were drastically reduced in magnitude by adopting the population‐averaged AIF for the MR analysis instead of the measured ones (from 51·5% to 18·9% for K^trans and from 21·7% to 4·1% for k_ep in high‐K^trans region; from 73·0% to 29·4% for K^trans and from 63·4% to 24·5% for k_ep in low‐K^trans region). The preliminary results showed the feasibility in the interchangeable use of the two imaging modalities in assessing cervical cancers.     

Validation of the acetylene rebreathing method for measurement of cardiac output at rest and during high-intensity exercise

The use of the acetylene rebreathing method to estimate cardiac output (CO) during high-intensity exercise, which may be influenced by recirculation of acetylene, has not been validated. This study was designed to validate the acetylene rebreathing method to measure CO during high-intensity exercise using the direct Fick method. CO was measured at rest and during exercise at 25%, 50%, 75% and 90% of the nine subjects maximum oxygen uptake (VO _2max) by the direct Fick and acetylene rebreathing method. CO measured by the acetylene rebreathing method correlated with work rate (r=0·90, P<0·01) and with oxygen uptake (r=0·94, P<0·01). The correlation coefficient of CO between both methods was r=0·91 (P<0·01). There was no significant difference in CO measured by each method at rest as well as at each work rate. The difference in CO between each method was greater at lower CO than at higher CO. At 90% of VO _2max, the CO measured by acetylene rebreathing was nearly identical to that measured by the Fick method. It can be concluded that acetylene rebreathing for measurement of CO is valid not only at rest but also during exercise, especially during high-intensity exercise.     

Technetium‐99m‐anti‐tumour necrosis factor alpha scintigraphy as promising predictor of response to corticotherapy in chronic active Graves' ophthalmopathy

It has been suggested that technetium‐99m (99mTc)‐anti‐tumour necrosis factor alpha (TNF‐α) scintigraphy (SCI) may be a useful diagnostic tool in Graves' ophthalmopathy (GO). This study evaluated whether orbit total radioactivity uptake on SCI could be used to predict corticosteroid therapy (CorT) responses in active‐GO patients. A longitudinal study of patients with active GO defined by Clinical Active Score (CAS) >3/7 was done. Clinical, laboratory and SCI evaluations were performed at baseline and 3 months after concluding intravenous CorT. SCI (planar and tomographic) was assessed after intravenous injection of 10 mCi of 99mTc‐anti‐TNF‐α. Orbits and cerebral hemispheres were defined as regions of interest (ROIs) to enable orbit/hemisphere ROI‐ratios of total radioactive uptake. ROI‐ratios were considered positive at >2·5. Average total radiation uptake (TRU) was also determined for each orbit (AVG_ROI). Clinical, laboratory and SCI data were compared between responders (CAS became inactive) and non‐responders to CorT (18 patients). At baseline, AVG_ROI were higher in active OG orbits (67·3 cps) than in inactive ones (33·6 cps; P<0·05). AVG_ROI (absolute values) reduced (?29·9 cps) in CorT responders and tended (P = 0·067) to differ from variations occurred in non‐responders (+6·9 cps in patients with maintained CAS positivity post‐treatment). Higher baseline ROI‐ratios (4·9 versus 3·3; P = 0·056) and its pronounced reductions following CorT (?37% versus +56% in non‐responders; P = 0·036) tended to be associated with good CorT responses in the subgroup of GO history ≥1 year. SCI showed a good association with active eye disease and may be an additional tool to identify CorT responders.     

Relationship between peak cardiac pumping capability and indices of cardio-respiratory fitness in healthy individuals

Cardiac power output (CPO) is a unique and direct measure of overall cardiac function (i.e. cardiac pumping capability) that integrates both flow‐ and pressure‐generating capacities of the heart. The present study assessed the relationship between peak exercise CPO and selected indices of cardio‐respiratory fitness. Thirty‐seven healthy adults (23 men and 14 women) performed an incremental exercise test to volitional fatigue using the Bruce protocol with gas exchange and ventilatory measurements. Following a 40‐min recovery, the subjects performed a constant maximum workload exercise test at or above 95% of maximal oxygen consumption. Cardiac output was measured using the exponential CO₂ rebreathing method. The CPO, expressed in W, was calculated as the product of the mean arterial blood pressure and cardiac output. At peak exercise, CPO was well correlated with cardiac output (r = 0·92, P<0·01), stroke volume (r = 0·90, P<0·01) and peak oxygen consumption (r = 0·77, P<0·01). The coefficient of correlation was moderate between CPO and anaerobic threshold (r = 0·47, P<0·01), oxygen pulse (r = 0·57, P<0·01), minute ventilation (r = 0·53, P<0·01) and carbon dioxide production (r = 0·56, P<0·01). Small but significant relationship was found between peak CPO and peak heart rate (r = 0·23, P<0·05). These findings suggest that only peak cardiac output and stroke volume truly reflect CPO. Other indices of cardio‐respiratory fitness such as oxygen consumption, anaerobic threshold, oxygen pulse, minute ventilation, carbon dioxide production and heart rate should not be used as surrogates for overall cardiac function and pumping capability of the heart.     

Body composition,maximal aerobic performance and inflammatory biomarkers in endurance-trained athletes

This study was designed to examine the relationships between body composition, cardiorespiratory fitness and simultaneously measured inflammatory parameters in endurance-trained athletes. In 20 well-trained rowers (19·0 ± 2·9 years; 185·6 ± 4·8 cm; 85·7 ± 10·8 kg; 17·1 ± 5·1% body fat; maximal oxygen consumption [VO₂max]: 63·9 ± 8·5 ml min⁻¹ kg⁻¹), body composition was measured by dual-energy X-ray absorptiometry and cardiorespiratory fitness by direct VO₂max test. Twelve inflammatory factors [interleukin (IL)-2, IL-4, IL-6, IL-8, IL-10, vascular endothelial growth factor, interferon-gamma (IFN-γ), tumour necrosis factor-alpha, IL-1α, IL-1β, monocyte chemoattractant protein-1 (MCP-1), epidermal growth factor (EGF)] were analysed from serum samples. Serum IFN-γ was related (P<0·05) to fat-free mass (FFM) (r = −0·56) and muscle mass (r = −0·50). The stepwise regression analysis showed that IFN-γ explained 27·5%, and IFN-γ and IL-6 together explained 39·8% of the variability of FFM, while IFN-γ explained 21·1%, and IFN-γ together with EGF explained 36·6% of the variability of muscle mass in male rowers. Serum IL-8 (r = −0·65) and VEGF (r = −0·48) correlated (P<0·05) with VO₂max kg⁻¹. Serum IL-8 explained 38·5% of the variability of VO₂max kg⁻¹. Significant correlations were also found among several inflammatory parameters, indicating that various inflammatory cytokines act on the body as an ensemble. In conclusion, this cross-sectional study in endurance-trained male rowers showed that FFM and muscle mass were negatively correlated with serum IFN-γ level, whereas cardiorespiratory fitness was negatively related to serum IL-8 level.     

Whole body,regional fat accumulation,and appetite‐related hormonal response after hypoxic training

The present study was conducted to determine change in regional fat accumulation and appetite‐related hormonal response following hypoxic training. Twenty sedentary subjects underwent hypoxic (n = 9, HYPO, FiO₂ = 15%) or normoxic training (n = 11, NOR, FiO₂ = 20·9%) during a 4‐week period (3 days per week). They performed a 4‐week training at 55% of maximal oxygen uptake (O_2max) for each condition. Before and after the training period, O_2max, whole body fat mass, abdominal fat area, intramyocellular lipid content (IMCL), fasting and postprandial appetite‐related hormonal responses were determined. Both groups showed a significant increase in O_2max following training (P<0·05). Whole body and segmental fat mass, abdominal fat area, IMCL did not change in either group. Fasting glucose and insulin concentrations significantly reduced in both groups (P<0·05). Although area under the curve for the postprandial blood glucose concentrations significantly decreased in both groups (P<0·05), the change was significantly greater in the HYPO group than in the NOR group (P<0·05). Changes in postprandial plasma ghrelin were similar in both groups. A significant reduction of postprandial leptin response was observed in both groups (P<0·05), while postprandial glucagon‐like peptide‐1 (GLP‐1) concentrations increased significantly in the NOR group only (P<0·05). In conclusion, hypoxic training for 4 weeks resulted in greater improvement in glucose tolerance without loss of whole body fat mass, abdominal fat area or IMCL. However, hypoxic training did not have synergistic effect on the regulation of appetite‐related hormones.     

Commonly used reference values underestimate oxygen uptake in healthy, 50‐year‐old Swedish women

Cardiopulmonary exercise testing (CPET) is the gold standard among clinical exercise tests. It combines a conventional stress test with measurement of oxygen uptake (V_O2) and CO₂ production. No validated Swedish reference values exist, and reference values in women are generally understudied. Moreover, the importance of achieved respiratory exchange ratio (RER) and the significance of breathing reserve (BR) at peak exercise in healthy individuals are poorly understood. We compared V_O2 at maximal load (peakV_O2) and anaerobic threshold (V_O2@AT) in healthy Swedish individuals with commonly used reference values, taking gender into account. Further, we analysed maximal workload and peakV_O2 with regard to peak RER and BR. In all, 181 healthy, 50‐year‐old individuals (91 women) performed CPET. PeakV_O2 was best predicted using Jones et al. (100·5%). Furthermore, underestimation of peakV_O2 in women was found for all studied reference values (P<0·001) and was largest for Hansen‐Wasserman: women had 115% of predicted peakV_O2, while men had 103%. PeakV_O2 was similar in subjects with peak RER of 1–1·1 and RER > 1·1 (2 328·7 versus 2 176·7 ml min^?1, P = 0·11). Lower BR (≤30%) related to significantly higher peakV_O2 (P<0·001). In conclusion, peakV_O2 was best predicted by Jones. All studied reference values underestimated oxygen uptake in women. No evidence for demanding RER > 1·1 in healthy individuals was found. A lowered BR is probably a normal response to higher workloads in healthy individuals.