Oxynet: A collective intelligence that detects ventilatory thresholds in cardiopulmonary exercise tests.

The problem of the automatic determination of the first and second ventilatory thresholds (VT1 and VT2) from cardiopulmonary exercise test (CPET) still leads to controversy. The reliability of the gold standard methodology (i.e. expert visual inspection) feeds into the debate and several authors call for more objective automatic methods to be used in the clinical practice. In this study, we present a framework based on a collaborative approach, where a web-application was used to crowd-source a large number (1245) of CPET data of individuals with different aerobic fitness. The resulting database was used to train and test an artificial intelligence (i.e. a convolutional neural network) algorithm. This automatic classifier is currently implemented in another web-application and was used to detect the ventilatory thresholds in the available CPET. A total of 206 CPET were used to evaluate the accuracy of the estimations against the expert opinions. The neural network was able to detect the ventilatory thresholds with an average mean absolute error of 178 (198) mlO2/min (11.1%, r = 0.97) and 144 (149) mlO2/min (6.1%, r = 0.99), for VT1 and VT2 respectively. The performance of the neural network in detecting VT1 deteriorated in case of individuals with poor aerobic fitness. Our results suggest the potential for a collective intelligence system to outperform isolated experts in ventilatory thresholds detection. However, the inclusion of a larger number of VT1 examples certified by a community of experts will be likely needed before the abilities of this collective intelligence can be translated into the clinical use of CPET.

Stress and recovery in sports: Effects on heart rate variability, cortisol, and subjective experience.

This study aimed to investigate (1) the time-variations and (2) the repeated measures relationship between training load (TL) and psychological and physiological parameters and performance. Data were collected around 12-weeks of training in fifteen national swimmers. Psychological states were assessed using the RESTQ-36-R-Sport Questionnaire and the Sport Emotion Questionnaire. Subjects collected four saliva samples throughout the day at 1) 7 a.m. immediately after waking, 2) 30 min after waking, 3) 60 min after waking, and 4) 8 p.m., allowing us to calculate the area under the curve with respect to ground (AUCg) and the sAA over cortisol ratio (AOC). Finally, heart rate variability was computed using a submaximal 5'-5' running test. Time variations were analyzed throughout repeated measures ANOVA and repeated measures correlations were run using the "rmcorr" R package. Recovery-stress states and emotional markers showed quadratic curves, while parasympathetic markers showed linear trajectories over time. Significant associations over time were found between TL and recovery, stress, emotional states, lnRMSSD and the AOC. Taken together, these results provided evidence that psychological and physiological states do not follow the same dynamics (i.e., linear vs. quadratic vs. no variation) in the functional training periodization condition. Our study also provided evidence that recovery-stress states, emotional states, lnRMSSD, and the AOC were of interest due to their intra-individual associations around the time with TL.

Intermittent versus constant aerobic exercise in middle-aged males: acute effects on arterial stiffness and factors influencing the changes.

PURPOSE: Both constant and intermittent acute aerobic exercises have been found to decrease arterial stiffness. However, direct comparisons of these two types of exercise are sparse. It is not known which type of exercise has the greatest effect. METHODS: We evaluated the haemodynamic responses in 15 males (age 48.5 ± 1.3 years; BMI 27.5 ± 0.8 kg m-2) following acute constant (CE) and intermittent cycling exercise (IE). Duration and heart rate were matched during both exercises (131.8 ± 3.2 bpm for CE and 132.0 ± 3.1 bpm for IE). Central and peripheral arterial stiffness was assessed through pulse wave velocity (PWV). Plasma concentrations of nitric oxide (NO), atrial natriuretic peptide (ANP), blood lactate, noradrenaline, and adrenaline were measured before and after each exercise. RESULTS: Central (+ 1.8 ± 7.4 and - 6.5 ± 6.8% for CE and IE) and upper limb PWV (+ 2.7 ± 6.2 and - 8 ± 4.6% for CE and IE) were not significantly altered although a small decrease (small effect size) was observed after IE. However, lower limb PWV significantly decreased after exercises (- 7.3 ± 5.7 and - 15.9 ± 4% after CE and IE), with a larger effect after IE. CONCLUSIONS: Greater decrease in lower limb PWV occurred after IE despite greater heart rate. This may be due to the higher blood levels of lactate during IE, while NO, ANP, noradrenaline, and adrenaline levels remained not statistically different from CE. These results underlined the importance of lactate in triggering the post-exercise vascular response to exercise, as well as its regional characteristic.

Elite swimmers' internal markers trajectories in ecological training conditions.

This study examined the trajectories of elite swimmers' recovery-stress states and cardiac vagal-related markers during a 3-month training period preceding the national championship and their within-person relationships with perceived control. A Multilevel Growth Curve Analysis (MGCA) approach was used with 21 male elite swimmers. Four waves of assessments of psychological (stress, recovery, perceived control) and physiological (heart rate recovery, heart rate variability) markers were completed during a 3month training preparation leading to a major competition. Results of MGCA revealed (a) a significant positive linear effect of time (ie, linear increase over time) and a significant negative quadratic effect of time (ie, inverted U shape over time) on perceived stress whereas the opposite pattern of results was observed for perceived recovery; and (b) a significant positive linear effect of time for nHRR60. Both at level 1 (within-person level of analysis) and 2 (between-person level of analysis), perceived control was (a) positively associated with athletes' perceived recovery and parasympathetic markers (ie, MeanRR; pNN50); and (b) negatively related to swimmers' perceived stress. Results also indicated that within-person interactions of perceived control with time reached significance for general recovery and HRV. Finally, within-person interaction of perceived control with squared time reached significance for subjective sport-specific and total stress. Overall, this study provided insights into the key role played by perceived control on both psychological and physiological markers related to recovery-stress states' levels during the 3-month training period preceding the national championship.

Aerial and Terrestrial Patterns: A Novel Approach to Analyzing Human Running.

Biomechanical parameters are often analyzed independently, although running gait is a dynamic system wherein changes in one parameter are likely to affect another. Accordingly, the Volodalen® method provides a model for classifying running patterns into 2 categories, aerial and terrestrial, using a global subjective rating scoring system. We aimed to validate the Volodalen® method by verifying whether the aerial and terrestrial patterns, defined subjectively by a running coach, were associated with distinct objectively-measured biomechanical parameters. The running patterns of 91 individuals were assessed subjectively using the Volodalen® method by an expert running coach during a 10-min running warm-up. Biomechanical parameters were measured objectively using the OptojumpNext® during a 50-m run performed at 3.3, 4.2, and 5 m·s(-1) and were compared between aerial- and terrestrial-classified subjects. Longer contact times and greater leg compression were observed in the terrestrial compared to the aerial runners. The aerial runners exhibited longer flight time, greater center of mass displacement, maximum vertical force and leg stiffness than the terrestrial ones. The subjective categorization of running patterns was associated with distinct objectively-quantified biomechanical parameters. Our results suggest that a subjective holistic assessment of running patterns provides insight into the biomechanics of running gaits of individuals.

Typology of "Fatigue" by Heart Rate Variability Analysis in Elite Nordic-skiers.

This study investigated changes in heart rate variability (HRV) in elite Nordic-skiers to characterize different types of "fatigue" in 27 men and 30 women surveyed from 2004 to 2008. R-R intervals were recorded at rest during 8 min supine (SU) followed by 7 min standing (ST). HRV parameters analysed were powers of low (LF), high (HF) frequencies, (LF+HF) (ms(2)) and heart rate (HR, bpm). In the 1 063 HRV tests performed, 172 corresponded to a "fatigue" state and the first were considered for analysis. 4 types of "fatigue" (F) were identified: 1. F(HF(-)LF(-))SU_ST for 42 tests: decrease in LFSU (- 46%), HFSU (- 70%), LFST (- 43%), HFST (- 53%) and increase in HRSU (+ 15%), HRST (+ 14%). 2. F(LF(+) SULF(-) ST) for 8 tests: increase in LFSU (+ 190%) decrease in LFST (- 84%) and increase in HRST (+ 21%). 3. F(HF(-) SUHF(+) ST) for 6 tests: decrease in HFSU (- 72%) and increase in HFST (+ 501%). 4. F(HF(+) SU) for only 1 test with an increase in HFSU (+ 2161%) and decrease in HRSU (- 15%). Supine and standing HRV patterns were independently modified by "fatigue". 4 "fatigue"-shifted HRV patterns were statistically sorted according to differently paired changes in the 2 postures. This characterization might be useful for further understanding autonomic rearrangements in different "fatigue" conditions.

Changes in tissue oxygen saturation with calf compression sleeve: before, during and after a cycling exercise.

AIM: The purpose of this study was to examine the changes in tissue oxygen saturation (StO2) with calf compression sleeves, before, during and after a cycling exercise. METHODS: Eleven athletes came to the laboratory two times, to complete the same session with or without calf compression sleeves, in a randomized order. The session included a 15-min incremental cycling exercise: 3 min at each intensity - 40, 80, 120, 160 and 200 W, preceded (baseline) and followed (recovery) by a 10-min period at rest in seated position. Calf StO2 was recorded using near infrared spectroscopy during the three last min of the baseline period, during the cycling exercise and during the recovery period. RESULTS: Baseline StO2 was significantly increased with the compression sleeves (P<0.001; +24.8±3.5%). During the cycling exercise, StO2 was significantly increased with the compression sleeves only at 40 W (P<0.05; +8.2±3.7%) and 80 W (P<0.05; +7.9±3.7%). At 120 W (P=0.23; +5.0±4.0%), 160 W (P=0.38; +3.9±4.1%) and 200 W (P=0.81; -0.1±4.9%), no significant difference was found with compression sleeves. During the recovery period, StO2 was significantly increased with the compression sleeves (1 to 10 min: P<0.001; +10.5±1.3%). CONCLUSION: This study shows that wearing calf compression sleeves increases StO2 at rest (before and after an exercise) and at low intensities in cycling (40 W and 80 W). At high intensities (120 W and more), compression sleeves is not useful to increase StO2.

Effects of three postexercice recovery treatments on femoral artery blood flow kinetics.

AIM: This study aimed to compare the kinetics of muscle leg blood flow during three recovery treatments following a prolonged exercise: contrast water therapy (CWT), compression stockings (CS) or passive recovery (PR). METHODS: Fifteen men came to the laboratory three times to perform a 45-min exercise followed 5 min after by a standardized 12-min recovery treatment in upright position, alternating between two vats every 2 min: CWT (cold: ~12 °C to warm: 36 °C), CS (~20 mmHg) or PR. The order of treatments was randomized. Blood flow was measured using Doppler ultrasound during the recovery treatments (i.e., min 3, 5, 7 and 9) in the superficial femoral artery distally to the common bifurcation (~3 cm) (above the water and stocking). RESULTS: Blood flow was significantly higher during CWT (P<0.01; +22.91%) and CS (P<0.05; +15.26%) than during PR. Although no statistical difference between CWT and CS was observed, effect sizes were larger during CWT (large) than during CS (moderate). No changes in blood flow occurred in the femoral artery between hot and cold transitions of CWT. CONCLUSION: During immediate recovery of a high intensity exercise, CWT and CS trigger higher femoral artery blood flow than PR. Moreover, effect sizes were greater during CWT than during CS.

Changes in femoral artery blood flow during thermoneutral, cold, and contrast-water therapy.

AIM: The purpose of this study was to examine the changes in femoral artery blood flow during cold water immersion (CWI), contrast water therapy (CWT) and thermoneutral water immersion (TWI). METHODS: Ten athletes came to the laboratory three times, to complete a 20-min procedure in upright position: 4 min in air (baseline), then 16-min full leg TWI (~35 °C), CWI (~12 °C) or CWT (2:2 ~12 °C to ~35 °C) min ratio, in a random order. Blood flow was measured every 2 min: baseline (i.e. min 3 and 1) and throughout water immersion (i.e. min 1, 3, 5, 7, 9, 11, 13 and 15), using Doppler ultrasound in the superficial femoral artery, distal to the common bifurcation (~3 cm), above the water and stocking. RESULTS: Compared with baseline, blood flow was significantly higher throughout TWI (min 1 to 15: P<0.001; +74.6%), significantly lower during CWI (from min 7 to 15: P<0.05; -16.2%) and did not change during CWT (min 1 to 15). No changes in blood flow occurred between the hot and cold transitions of CWT. CONCLUSION: This study shows that external hydrostatic pressure (TWI ~35 °C) significantly increases femoral artery blood flow. We also show that associating hydrostatic pressure with cooling (CWI ~12 °C) decreases femoral artery blood flow after a sufficient duration, whereas associating hydrostatic pressure with alternating brief exposures to contrasted temperatures does not change femoral artery blood flow under resting conditions.

The influence of surface on the running velocities of elite and amateur orienteer athletes.

We compared the reduction in running velocities from road to off-road terrain in eight elite and eight amateur male orienteer athletes to investigate whether this factor differentiates elite from amateur athletes. On two separate days, each subject ran three 2-km time trials and three 20-m sprints "all-out" on a road, on a path, and in a forest. On a third day, the running economy and maximal aerobic power of individuals were assessed on a treadmill. The elite orienteer ran faster than the amateur on all three surfaces and at both distances, in line with their better running economy and aerobic power. In the forest, the elites ran at a slightly higher percentage of their 2-km (∼3%) and 20-m (∼4%) road velocities. Although these differences did not exhibit traditional statistical significance, magnitude-based inferences suggested likely meaningful differences, particularly during 20-m sprinting. Of course, cognitive, mental, and physical attributes other than the ability to run on different surfaces are required for excellence in orienteering (e.g., a high aerobic power). However, we suggest that athlete-specific assessment of running performance on various surfaces and distances might assist in tailoring training and identifying individual strengths and/or weaknesses in an orienteer.

Ventilatory thresholds determined from HRV: comparison of 2 methods in obese adolescents.

The development of personalised training programmes is crucial in the management of obesity. We evaluated the ability of 2 heart rate variability analyses to determine ventilatory thresholds (VT) in obese adolescents. 20 adolescents (mean age 14.3±1.6 years and body mass index z-score 4.2±0.1) performed an incremental test to exhaustion before and after a 9-month multidisciplinary management programme. The first (VT1) and second (VT2) ventilatory thresholds were identified by the reference method (gas exchanges). We recorded RR intervals to estimate VT1 and VT2 from heart rate variability using time-domain analysis and time-varying spectral-domain analysis. The coefficient correlations between thresholds were higher with spectral-domain analysis compared to time-domain analysis: Heart rate at VT1: r=0.91 vs. =0.66 and VT2: r=0.91 vs. =0.66; power at VT1: r=0.91 vs. =0.74 and VT2: r=0.93 vs. =0.78; spectral-domain vs. time-domain analysis respectively). No systematic bias in heart rate at VT1 and VT2 with standard deviations <6 bpm were found, confirming that spectral-domain analysis could replace the reference method for the detection of ventilatory thresholds. Furthermore, this technique is sensitive to rehabilitation and re-training, which underlines its utility in clinical practice. This inexpensive and non-invasive tool is promising for prescribing physical activity programs in obese adolescents.

Effect of slope and footwear on running economy and kinematics.

Lower energy cost of running (Cr) has been reported when wearing minimal (MS) vs traditional shoes (TS) on level terrain, but the effect of slope on this difference is unknown. The aim of this study was to compare Cr, physiological, and kinematic variables from running in MS and TS on different slope conditions. Fourteen men (23.4 ± 4.4 years; 177.5 ± 5.2 cm; 69.5 ± 5.3 kg) ran 14 5-min trials in a randomized sequence at 10 km/h on a treadmill. Subjects ran once wearing MS and once wearing TS on seven slopes, from -8% to +8%. We found that Cr increased with slope gradient (P < 0.01) and was on average 1.3% lower in MS than TS (P < 0.01). However, slope did not influence the Cr difference between MS and TS. In MS, contact times were lower (P < 0.01), flight times (P = 0.01) and step frequencies (P = 0.02) were greater at most slope gradients, and plantar-foot angles - and often ankle plantar-flexion (P = 0.01) - were greater (P < 0.01). The 1.3% difference between footwear identified here most likely stemmed from the difference in shoe mass considering that the Cr difference was independent of slope gradient and that the between-footwear kinematic alterations with slope provided limited explanations.

Autonomic recovery following sprint interval exercise.

The autonomic nervous activity was assessed following supramaximal exercise through heart rate (HR) and blood pressure (BP) variability (HRV and BPV) and baroreflex sensitivity (BRS). The beat-to-beat HR and BP were recorded during the supine and standing states before (PRE) and at 60 (R60) and 120 min (R120) following single (one Wingate, 1W) and multiple sprint intervals (four Wingates interspersed with 4 min of light cycling, 4W). The supine low frequency (LF) component was increased (P<0.001) and the high frequency (HF) was reduced (P<0.01) at R60 (LF, 178.1 ± 11.0; HF, 74.8 ± 10.5) compared with PRE (LF, 140.2 ± 7.4; HF, 110.4 ± 7.2) after both exercises. Supine systolic BPV LF:HF was higher at R60 (4.6 ± 1.4) compared with PRE (6.8 ± 2.4) only after 4W (P=0.035). Supine BRS was lower (P<0.001) at R60 (6.8 ± 1.1) than at PRE (15.3 ± 1.8) and R120 (11.3 ± 1.3). BRS at R120 remained lower after 4W (P=0.02). Standing BRS was less (P<0.001) at R60 (2.3 ± 0.5) than at PRE (5.6 ± 0.8) or R120 (3.7 ± 0.6) and returned to PRE values only after 1W. We concluded that (a) autonomic balance is shifted to a greater sympathetic and less parasympathetic activation following both types of exercise, (b) it takes longer than 1 h to recover following supramaximal exercise and (c) the recovery is longer after 4W than 1W.

Heart rate variability to assess ventilatory thresholds: reliable in cardiac disease?

BACKGROUND: The first (VT1) and second (VT2) ventilatory thresholds are landmarks to tailor exercise rehabilitation in coronary artery disease (CAD) or chronic heart failure (CHF). Methods allowing VT1 and VT2 determination based on heart rate variability (HRV) have been proposed but not yet evaluated in these patients. DESIGN: To determine the heart rate (HR) associated with VT1 and VT2 by three methods of HRV analyses. METHODS: Fourteen CHF and 24 CAD patients performed an exercise test on a cycle ergometer (10 -W every minute until exhaustion). VT1 and VT2 were determined with the 'respiratory equivalent' method. HR at VT1 was determined with the standard deviation (SD) of R⊟R intervals (VT(SD)) and of the instantaneous beat-to-beat variability of the Poincaré plot method (VT(Poincaré)). HR at VT1 and VT2 was determined through a time-varying HRV analysis method (VT(TV1) and VT(TV2), respectively). RESULTS: HR at VT(SD) was significantly higher than HR at VT1. No significant differences were observed between HR at VT(Poincaré), VT(TV1), and at VT1, nor between HR at VT(TV2) and VT2. HR at VT(SD), VT(Poincaré), and VT1 were significantly correlated, but with a low r (2) value and a large mean HR difference. With the time-varying method, the mean HR difference was lower than 5% and the correlation coefficients were higher (especially for VT(TV2)). CONCLUSIONS: SD and Poincaré plot methods lead to substantial inaccuracy in HR estimates. The time-varying HRV analysis led to strong correlation coefficients and low limits of agreement. Therefore, this method may be a promising, low-cost tool for non-invasive assessment of the ventilatory thresholds in cardiac disease.

Compression sleeves increase tissue oxygen saturation but not running performance.

The purpose of this study was to determine the effects of calf compression sleeves on running performance and on calf tissue oxygen saturation (StO2) at rest before exercise and during recovery period. 14 moderately trained athletes completed 2 identical sessions of treadmill running with and without calf compression sleeves in randomized order. Each session comprised: 15 min at rest, 30 min at 60% maximal aerobic velocity determined beforehand, 15 min of passive recovery, a running time to exhaustion at 100% maximal aerobic velocity, and 30 min of passive recovery. Calf StO2 was determined by near infra-red spectroscopy and running performance by the time to exhaustion. Compression sleeves increased significantly StO2 at rest before exercise (+ 6.4±1.9%) and during recovery from exercise (+ 7.4±1.7% and + 10.7±1.8% at 20th and 30th min of the last recovery period, respectively). No difference was observed between the times to exhaustion performed with and without compression sleeves (269.4±18.4 s and 263.3±19.8 s, respectively). Within the framework of this study, the compression sleeves do not improve running performance in tlim. However the StO2 results argue for further interest of this garment during effort recovery.

Evaluation of cardiorespiratory functional reserve from arm exercise in the elderly.

BACKGROUND: When the subject is not able to satisfy traditional testing procedures, alternative exercises or indices such as arm cranking or the oxygen uptake efficiency slope (OUES) have been proposed. However, the OUES has not yet been used on elderly subjects from an exercise performed with the arms. OBJECTIVE: The aim of our study was to evaluate the possibility of using the OUES as an index of the cardiorespiratory functional reserve in the elderly when the exercise evaluation test is performed with the arms and when this parameter is estimated from submaximal responses. METHODS: Seventeen adults (62-82 years) undergoing total joint arthroplasty of the hip took part in this study. Maximal incremental exercise tests were performed on an arm crank ergometer 1 month before (T1) and 2 months after (T2) surgery. Gas exchanges were measured continuously to determine oxygen consumption at peak exercise (V˙O2 peak) and were used to calculate the OUES. The correlation coefficient was calculated between V˙O2 peak and OUES, and their relative changes between T1 and T2. RESULTS: V˙O2 peak was not significantly different between T1 and T2: 10.3 ± 0.7 and 9.8 ± 0.5 mL/min per kilogramme respectively. The OUES estimated from submaximal responses did not show a significant difference between T1 and T2. Significant correlations were observed between individual V˙O2 peak and OUES, as well as at T1 and T2. CONCLUSION: The use of arm cranking exercises and the calculation of the OUES from the submaximal respiratory response can be used for the objective quantification of cardiorespiratory functional reserve in the elderly.

Effects of a primary rehabilitation programme on arterial vascular adaptations in an individual with paraplegia.

OBJECTIVE: Evaluation of the effects of 6 weeks of wheelchair endurance training on arterial stiffness in an individual with paraplegia. METHODS: A 22-year-old male patient with complete (ASIA A) paraplegia (T11) was tested before and after training (30 minutes three times per week). Physical performance and cardiorespiratory response were evaluated during a maximal progressive test. Heart rate (HR), blood pressure, stroke volume and arterial carotid-wrist and carotid-ankle pulse wave velocity (PWV) were measured at rest. RESULTS: Maximal responses registered (maximal tolerated power, VO2 peak) during the exercise test were increased after training. At rest, HR as PWV decreased, whereas cardiac output and blood pressure remained constant. CONCLUSION: Continuous exposure of the subject to a repeated high intensity exercise bout for 6 weeks elevated fitness level. Such a regular practice might also constitute a major way to trigger vascular remodelling beyond to the trained body part.

Cardiovascular rehabilitation increase arterial compliance in type 2 diabetic patients with coronary artery disease.

AIMS: The effect of a cardiovascular rehabilitation program on arterial compliance in type 2 diabetes mellitus with coronary disease was studied. METHODS: Hemodynamic data and arterial compliance were measured with a tonometer (HDI/Pulse wave CR-2000) in coronary artery disease patients with (n=32) and without (n=24) type 2 diabetes before and after a 6-week multidisciplinary cardiac rehabilitation program. RESULTS: A decrease in heart rate and an increase in stroke volume without significant change in resting cardiac output were obtained in diabetic patients. Arterial compliance of both small and large arteries was significantly increased. In 10 diabetic patients, this increase could be related to an increase in the anti-hypertensive treatment and to the decreased blood pressure. In the 22 remainders, the small artery compliance was significantly increased independently of blood pressure change. CONCLUSIONS: Exercise training as well as optimization of diabetes and dyslipidemia treatment could explain the improvement of arterial compliance. If these changes are long-lasting and if they improve prognosis remains to be evaluated.

Military diving training improved arterial compliance.

This study was aimed at investigating whether repeated SCUBA diving might induce long term cardiovascular and autonomic modifications. In 11 military mine clearance diving students, arterial compliance (ultrasound scan study of brachial artery and ratio of stroke volume to pulse pressure: SV/PP), resting spectral analyses of heart rate and blood pressure variability, and a cold pressor test were performed before and after a 15-week military diving training course. After the diving training, arterial compliance was improved, as indicated by the significant increase in brachial arterial compliance (from 24+/-10 to 37+/-14 ml.mmHg (-1)) and SV/PP (from 1.7+/-0.2 to 1.9+/-0.2 ml.mmHg (-1)), and by the significant decrease in systolic, diastolic and pulse pressures (from 130+/-8 to 120+/-7; from 71+/-4 to 67+/-4; and from 58+/-8 to 53+/-5 mmHg, respectively). The peak oxygen uptake increased significantly from 54.3+/-2.0 to 56.8+/-4.0 mL.kg (-1).min (-1). Finally, the vasoconstrictive response during the cold pressor test increased (p<0.05). These findings point to a positive effect of a 15-week military diving training course on vascular function, and for a concomitant development of some peripheral vascular acclimatization to cold.