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The present study investigated whether athletes can be classified as responders or non-responders based on their individual change in total hemoglobin mass (tHb-mass) following altitude training while also identifying the potential factors that may affect responsiveness to altitude exposure. Measurements were completed with 59 elite endurance athletes who participated in national team altitude training camps. Fifteen athletes participated in the altitude training camp at least twice. Total Hb-mass using a CO rebreathing method and other blood markers were measured before and after a total of 82 altitude training camps (1350-2500 m) in 59 athletes. In 46 (56%) altitude training camps, tHb-mass increased. The amount of positive responses increased to 65% when only camps above 2000 m were considered. From the fifteen athletes who participated in altitude training camps at least twice, 27% always had positive tHb-mass responses, 13% only negative responses, and 60% both positive and negative responses. Logistic regression analysis showed that altitude was the most significant factor explaining positive tHb-mass response. Furthermore, male athletes had greater tHb-mass response than female athletes. In endurance athletes, tHb-mass is likely to increase after altitude training given that hypoxic stimulus is appropriate. However, great inter- and intra-individual variability in tHb-mass response does not support classification of an athlete permanently as a responder or non-responder. This variability warrants efforts to control numerous factors affecting an athlete's response to each altitude training camp.

Type 1 diabetes may, in time, cause lung dysfunction including airflow limitation. We hypothesized that ventilatory flow morphology during a cardiopulmonary exercise test (CPET) would be altered in adult men with well-controlled type 1 diabetes. Thirteen men with type 1 diabetes [glycated hemoglobin A

Background Little is known about the associations of different depths of individualization of the exercise intervention on cardiorespiratory fitness (CRF), metabolic outcomes and cardiac autonomic regulation in at-risk subjects. This randomized trial compared the effect of general physical activity (PA) guideline -targeted and highly individualized exercise intervention on maximal oxygen uptake, heart rate variability, body composition, and glucose and lipid profiles in fertile-aged women with increased risk for gestational diabetes. Methods Forty-five women with previous gestational diabetes or BMI>30kg/m 2 were randomized into general advice without intervention (Group 1), individualized intervention planned according to PA questionnaires and general guidelines for exercise training (Group 2) and highly individualized intervention based on results from the pre-intervention cardiopulmonary exercise test (CPET) groups (Group 3). All subjects performed pre-intervention CPET on a cycle ergometer with step incremental protocol until volitional fatigue, followed by a 3-month intervention period and post-intervention CPET. Examinations included HRV assessment during CPET and body composition (bioimpedance), blood glucose and lipid profiles. Results Total dropout was 53.8% at various points of the study leaving 8 subjects in Group 1, 12 subjects in Group 2 and 10 subjects in Group 3. CRF improved only in Group 3 (+1.9 ml/kg/min, 95% CI 0.3 to 3.5). This was associated with an increase in high-density lipoprotein (0.18 mmol/L, 95% CI 0.04 to 0.32) and increased HRV. In Group 2, we found a decrease in body mass index (-0.7 kg/m 2, 95% CI -1.3 to -0.1), fasting insulin (-4.14 mU/L, 95% CI -6.58 to -1.70), insulin resistance (-1.21, 95% CI -1.88 to -0.54), and low-density lipoprotein (-0.44 mmol/L, 95% CI -0.79 to -0.09). The dropouts in Group 1 had significantly less weight, smaller waist circumference, less visceral fat, and higher maximal oxygen uptake compared to the continuers in Group 1. Conclusions To improve CRF and cardiac autonomic function the exercise intervention should be highly individualized. PA intervention focused to achieve general exercise guidelines is not enough to improve CRF over 3-month period but combined with weight loss has beneficial effects on the metabolic profile. In randomized controlled trials, dropout may be biased. Trial Registration clinicaltrials.gov (NCT01675271)

Adaptations to long-term exercise training in type 1 diabetes are sparsely studied. We examined the effects of a 1-year individualized training intervention on cardiorespiratory fitness, exercise-induced active muscle deoxygenation, and glycemic control in adults with and without type 1 diabetes. Eight men with type 1 diabetes (T1D) and 8 healthy men (CON) matched for age, anthropometry, and peak pulmonary O2 uptake, completed a 1-year individualized training intervention in an unsupervised real-world setting. Before and after the intervention, the subjects performed a maximal incremental cycling test, during which alveolar gas exchange (volume turbine and mass spectrometry) and relative concentration changes in active leg muscle deoxygenated (Δ[HHb]) and total (Δ[tHb]) hemoglobin (near-infrared spectroscopy) were monitored. Peak O2 pulse, reflecting peak stroke volume, was calculated (peak pulmonary O2 uptake/peak heart rate). Glycemic control (glycosylated hemoglobin A1c (HbA1c)) was evaluated. Both T1D and CON averagely performed 1 resistance-training and 3–4 endurance-training sessions per week (∼1 h/session at ∼moderate intensity). Training increased peak pulmonary O2 uptake in T1D (p = 0.004) and CON (p = 0.045) (group × time p = 0.677). Peak O2 pulse also rose in T1D (p = 0.032) and CON (p = 0.018) (group × time p = 0.880). Training increased leg Δ[HHb] at peak exercise in CON (p = 0.039) but not in T1D (group × time p = 0.052), while no changes in leg Δ[tHb] at any work rate were observed in either group (p > 0.05). HbA1c retained unchanged in T1D (from 58 ± 10 to 59 ± 11 mmol/mol, p = 0.609). In conclusion, 1-year adherence to exercise training enhanced cardiorespiratory fitness similarly in T1D and CON but had no effect on active muscle deoxygenation or glycemic control in T1D.

RISSANEN, A-P. E., H. O. TIKKANEN, A. S. KOPONEN, J. M. AHO, and J. E. PELTONEN. Central and Peripheral Cardiovascular Impairments Limit VO2peak in Type 1 Diabetes. Med. Sci. Sports Exerc., Vol. 47, No. 2, pp. 223-230, 2015. Purpose: Cardiovascular risk, predicted by peak O2 uptake (VO2peak), is increased in type 1 diabetes. We examined the contribution of central and peripheral mechanisms to VO2peak in physically active adults with type 1 diabetes. Methods: Seven men with type 1 diabetes and 10 healthy age-, anthropometry-, and physical activity-matched men performed incremental cycling exercise until volitional fatigue. Alveolar gas ex- change (turbine and mass spectrometry), cardiac function and systemic vascular resistance (impedance cardiography), and local active leg muscle deoxygenation and blood flow (near infrared spectroscopy) were monitored. Arterial-venous O2 difference was calculated (Fick principle). Blood volume (BV) (carbon monoxide rebreathing method) and glycemic control (glycosylated hemoglobin) were determined. Results: The group with diabetes had lower VO2peak than controls (47 T 5v s 56T 7m LImin j1 Ikg j1 fat-free mass, P G 0.05). At peak exercise, fat-free mass-adjusted stroke volume (SV) and cardiac output (CO) were lower and systemic vascular resistance was higher in the group with diabetes than those in controls (P G 0.05). Leg muscle blood flow was reduced independently of CO in the group with diabetes at peak exercise (P G 0.05), whereas arterial-venous O2 difference was similar in the groups throughout the exercise (P 9 0.05). The group with diabetes had lower relative BV than controls (P G 0.01), and BV correlated positively with peak SV and peak CO (P G 0.001). In the group with diabetes, peak SV and peak CO correlated (P G 0.05) and peak leg muscle blood flow tended to correlate (P = 0.070) inversely with glycosylated hemoglobin. Conclusions: Both central and peripheral cardiovascular impairments limit VO2peak in physically active adults with type 1 diabetes. Importantly, central limitations, and probably peripheral limitations as well, are asso

Type 1 diabetes is a metabolic disorder, which has been associated with decreased heart rate variability (HRV) and increased risk for adverse cardiac events. The aim of this paper was to examine HRV dynamics during a cardiorespiratory exercise test. 13 male subjects with type 1 diabetes (age 33.0±6.7 years) and 25 healthy male controls (age 33.7±7.6 years) participated the study. HRV was analysed from pre-exercise rest, warm-up, light exercise (40 W cycling), peak exercise, and recovery time periods. The main finding of the study was that subjects with diabetes had higher HRV complexity (higher multiscale entropy) during peak exercise when compared to healthy controls. HRV during rest, warm-up and light exercise was similar between the groups.

This study examined the associations of cardiorespiratory fitness (CRF) and leisure-time physical activity (LTPA) with health-related quality of life (HRQoL) in women at risk for gestational diabetes mellitus (GDM). The participants were 39 women planning pregnancy with a history of GDM and/or BMI >29 kg/m2 . We assessed CRF by measuring maximal oxygen consumption (VO2max ) during incremental cycle ergometer exercise until voluntary fatigue. LTPA was self-reported, and HRQoL assessed with the SF-36 Health Survey (SF-36). The mean (SD) VO2max was 27 (6) mL·kg-1 ·min-1 , and the mean LTPA was 2.6 (1.7) h/wk. After controlling for BMI, VO2max was positively associated with the SF-36 General Health scale (β 1.27, 95% CI: 0.09, 2.44, P=.035) and the Physical Component Summary (β 0.48, 95% CI: 0.14, 0.82, P=.007). The General Health scale (P=.023) and the Physical Component Summary (P=.011) differed even between those with very poor and poor CRF. After controlling for BMI, LTPA was positively associated with the SF-36 Physical Functioning scale (rs =.34, P=.039), the General Health scale (β 3.74, 95% CI: 0.64, 6.84, P=.020), and the Physical Component Summary (β 1.13 95% CI: 0.19, 2.06, P=.020). To conclude, CRF and LTPA were positively associated with perceived general health and physical well-being in women planning pregnancy and at risk for GDM. Even a slightly better CRF would be beneficial for well-being among women with low levels of CRF.

Blood O2 carrying capacity affects aerobic capacity (VO2max). Patients with type 1 diabetes have a risk for anaemia along with renal impairment, and they often have low VO2max. We investigated whether total haemoglobin mass (tHb-mass) and blood volume (BV) differ in men with type 1 diabetes (T1D, n = 12) presently without complications and in healthy men (CON, n = 23) (age-, anthropometry-, physical activity-matched), to seek an explanation for low VO2max. We determined tHb-mass, BV, haemoglobin concentration ([Hb]), and VO2max in T1D and CON. With similar (mean ± SD) [Hb] (144 vs. 145 g l−1), T1D had lower tHb-mass (10.1 ± 1.4 vs. 11.0 ± 1.1 g kg−1, P

Cheung, Stephen S, Niina E. Mutanen, Heikki M. Karinen, Anne S. Koponen, Heikki Kyro ̈ la ̈ inen, Heikki O. Tikkanen, and Juha E. Peltonen. Ventilatory chemosensitivity, cerebral and muscle oxygenation, and total hemoglobin mass before and after a 72-day Mt. Everest expedition. High Alt Med Biol 15:331–340, 2014.— Background: We investigated the effects of chronic hypobaric hypoxic acclimatization, performed over the course of a 72-day self-supported Everest expedition, on ventilatory chemosensitivity, arterial saturation, and tissue oxygenation adaptation along with total hemoglobin mass (tHb-mass) in nine experienced climbers (age 37 – 6 years, _ VO 2peak 55 – 7mL $ kg - 1 $ min - 1 ). Methods: Exercise-hypoxia tolerance was tested using a constant treadmill exercise of 5.5 km $ h - 1 at 3.8% grade (mimicking exertion at altitude) with 3-min steps of progressive normobaric poikilocapnic hypoxia. Breath-by-breath ventilatory responses, Sp o 2 , and cerebral (frontal cortex) and active muscle (vastus lateralis) oxygenation were measured throughout. Acute hypoxic ventilatory response (AHVR) was determined by linear regression slope of ventilation vs. Sp o 2 . PRE and POST ( < 15 days) expedition, tHb-mass was measured using carbon monoxide-rebreathing. Results: Post-expedition, exercise-hypoxia tolerance improved (11:32 – 3:57 to 16:30 – 2:09 min, p < 0.01). AHVR was elevated (1.25 – 0.33 to 1.63 – 0.38 L $ min - 1. % - 1 Sp o 2 , p < 0.05). Sp o 2 decreased throughout exercise-hypoxia in both trials, but was preserved at higher values at 4800 m post-expedition. Cerebral oxygenation decreased progressively with increasing exercise-hypoxia in both trials, with a lower level of deoxyhemoglobin POST at 2400, 3500 and 4800 m. Muscle oxygenation also decreased throughout exercise- hypoxia, with similar patterns PRE and POST. No relationship was observed between the slope of AHVR and cerebral or muscle oxygenation either PRE or POST. Absolute tHb-mass response exhibited great individual variation with a nonsignificant 5.4% increasing trend post-expedition (975 – 154 g PRE and 1025 – 124 g POST, p = 0.17). Conclusions: We conclude that adaptation to chronic hypoxia during a climbing expedition to Mt. Everest will increase hypoxic tolerance, AHVR, and cerebral but not muscle oxygenation, as measured during simulated acute hypoxia at sea level. However, tHb-mass did not increase significantly and improvement in cerebral oxygenation was not associated with the change in AHVR peerReviewed

We investigated whether leg and arm skeletal muscle, and cerebral deoxygenation, differ during incremental cycling exercise in men and women, and if women's lower capacity to deliver O2 affects tissue deoxygenation. Men (n=10) compared to women (n=10), had greater cardiac output, which with greater hemoglobin concentration produced greater absolute (QaO2) and body size-adjusted oxygen delivery (QaO2i) at peak exercise. Despite women's lower peak QaO2, their leg muscle deoxygenation was similar at a given work rate and QaO2, but less than in men at peak exercise (Δtissue saturation index -27.1 ± 13.2% vs. -11.8 ± 5.7%, P0.01; Δ[deoxyhemoglobin] 15.03 ± 8.57 μM vs. 3.73 ± 3.98 μM, P0.001). At peak exercise, oxygen uptake was associated both with QaO2 and leg muscle deoxygenation (both P0.01). Arm muscle and cerebral deoxygenation did not differ between sexes at peak exercise. Thus, both high O2 delivery and severe active muscle deoxygenation are determinants of good exercise performance, and active muscle deoxygenation responses are regulated partly in a sex-specific manner with an influence of exercise capacity.

In polycystic ovary syndrome (PCOS), cardiovascular risk is increased. Peak O2 uptake (Embedded Image) predicts the cardiovascular risk. We were the first to examine the contribution of systemic O2 delivery and arteriovenous O2 difference to Embedded Image in overweight and obese women with PCOS. Fifteen overweight or obese PCOS women and 15 age‐, anthropometry‐, and physical activity‐matched control women performed a maximal incremental cycling exercise test. Alveolar gas exchange (volume turbine and mass spectrometry), arterial O2 saturation (pulse oximetry), and cardiac output (CO) (impedance cardiography) were monitored. Hb concentration was determined. Arterial O2 content and arteriovenous O2 difference (C(a‐v)O2) (Fick equation) were calculated. Insulin resistance was evaluated by homeostasis model assessment (HOMA‐IR). PCOS women had lower Embedded Image than controls (40 ± 6 vs. 46 ± 5 mL/min/kg fat‐free mass [FFM], P = 0.011). Arterial O2 content was similarly maintained in the groups throughout the exercise test (P > 0.05). Linear regression analysis revealed a pronounced response of CO to increasing Embedded Image in PCOS women during the exercise test: A ∆CO/∆Embedded Image slope was steeper in PCOS women than in controls (β = 5.84 vs. β = 5.21, P = 0.004). Eventually, the groups attained similar peak CO and peak CO scaled to FFM (P > 0.05). Instead, C(a‐v)O2 at peak exercise was lower in PCOS women than in controls (13.2 ± 1.6 vs. 14.8 ± 2.4 mL O2/100 mL blood, P = 0.044). HOMA‐IR was similar in the groups (P > 0.05). The altered cardiorespiratory responses to exercise in overweight and obese PCOS women indicate that PCOS per se is associated with alterations in peripheral adjustments to exercise rather than with limitations of systemic O2 delivery., published version, peerReviewed

We used near-infrared spectroscopy to investigate whether leg and arm skeletal muscle and cerebral deoxygenation differ during incremental cycling exercise in men with type 1 diabetes (T1D, n=10, mean±SD age 33±7 years) and healthy control men (matched by age, anthrometry, and self-reported physical activity, CON, n=10, 32±7 years) to seek an explanation for lower aerobic capacity (˙VO2peak) often reported in T1D. T1D had lower ˙VO2peak (35±4mlkg(-1)min(-1) vs. 43±8mlkg(-1)min(-1), P0.01) and peak work rate (219±33W vs. 290±44W, P0.001) than CON. Leg muscle deoxygenation (↑ [deoxyhemoglobin]; ↓ tissue saturation index) was greater in T1D than CON at a given absolute submaximal work rate, but not at peak exercise, while arm muscle and cerebral deoxygenation were similar. Thus, in T1D compared with CON, faster leg muscle deoxygenation suggests limited circulatory ability to increase O(2) delivery as a plausible explanation for lower ˙VO2peak and earlier fatigue in T1D.