Changes In Maximal Oxygen Uptake Research Articles

Time-course for onset and decay of physiological adaptations in endurance trained athletes undertaking prolonged heat acclimation training

ABSTRACT Short-term heat acclimation (HA) appears adequate for maximizing sudomotor adaptations and enhancing thermal resilience in trained athletes. However, for enhanced erythropoiesis and transfer effects to exercise capacity in cooler environments, prolonged HA appears necessary. To establish the time-course for physiological adaptations and performance effects, 20 male elite cyclists were divided into an intervention group (HEAT; n = 10) completing 5 weeks of HA (six one-hour HA-training sessions per week) and control (n = 10) tested pre and post in hot (40°C) and cool conditions (20°C). HEAT completed tests at 40°C every week during HA with measures of sweat rate and [Na+] and a decay test 2 weeks after termination of HA. HEAT improved time for exhaustion by 15 min (p < 0.001) in the 40°C test, increased sweat rate by 0.44 L/hour (p < 0.001), and lowered sweat sodium concentration [Na+] by 14.1 mmol/L (p = 0.006) from pre- to post-HA, with performance returning to pre-HA levels in the 2-week decay test. Total hemoglobin mass (tHbmass) was increased by 30 grams (+3%, p = 0.048) after 3 weeks and 40 grams (+4%, p = 0.038) after 5 weeks in HEAT but returned to pre-HA levels at the 2-week decay test. HEAT improved incremental peak power output (+12 W, p = 0.001) without significant changes in maximal oxygen uptake (p = 0.094). In conclusion, improvements in heat exercise tolerance and sudomotor adaptations materialized during the first ~3 weeks and the entire 5 weeks of HA augmented both cool exercise capacity and tHbmass. However, the 2-week post-HA evaluation demonstrated a rapid decay of physiological adaptations and exercise capacity in the heat.

Combined intermittent hypoxic exposure at rest and continuous hypoxic training can maintain elevated hemoglobin mass after a hypoxic camp.

Athletes use hypoxic living and training to increase hemoglobin mass (Hbmass), but Hbmass declines rapidly upon return to sea level. We investigated whether intermittent hypoxic exposure (IHE) + continuous hypoxic training (CHT) after return to sea level maintained elevated Hbmass, and if changes in Hbmass were transferred to changes in maximal oxygen uptake (V̇o2max) and exercise performance. Hbmass was measured in 58 endurance athletes before (PRE), after (POST1), and 30 days after (POST2) a 27 ± 4-day training camp in hypoxia (n = 44, HYP) or at sea level (n = 14, SL). After returning to sea level, 22 athletes included IHE (2 h rest) + CHT (1 h training) in their training every third day for 1 mo (HYPIHE + CHT), whereas the other 22 HYP athletes were not exposed to IHE or CHT (HYPSL). Hbmass increased from PRE to POST1 in both HYPIHE + CHT (4.4 ± 0.7%, means ± SE) and HYPSL (4.1 ± 0.6%) (both P < 0.001). Compared with PRE, Hbmass at POST2 remained 4.2 ± 0.8% higher in HYPIHE + CHT (P < 0.001) and 1.9 ± 0.5% higher in HYPSL (P = 0.023), indicating a significant difference between the groups (P = 0.002). In SL, no significant changes were observed in Hbmass with mean alterations between -0.5% and 0.4%. V̇o2max and time to exhaustion during an incremental treadmill test (n = 35) were elevated from PRE to POST2 only in HYPIHE + CHT (5.8 ± 1.2% and 5.4 ± 1.4%, respectively, both P < 0.001). IHE + CHT possesses the potential to mitigate the typical decline in Hbmass commonly observed during the initial weeks after return to sea level.NEW & NOTEWORTHY Sets of 2-h intermittent hypoxic exposure + 1-h continuous hypoxic training, every third day, possess the potential to mitigate the typical decline in Hbmass that is commonly observed during the initial weeks after return to sea level from an altitude camp. Inclusion of IHE + CHT in the training regimen was also accompanied by improvements in V̇o2max and exercise performance in most but not all Tier 3-Tier 5 level endurance athletes during the training season.

Heavy-, Severe-, and Extreme-, but Not Moderate-Intensity Exercise Increase V̇o 2max and Thresholds after 6 wk of Training.

This study assessed the effect of individualized, domain-based exercise intensity prescription on changes in maximal oxygen uptake (V̇O 2max ) and submaximal thresholds. Eighty-four young healthy participants (42 females, 42 males) were randomly assigned to six age, sex, and V̇O 2max -matched groups (14 participants each). Groups performed continuous cycling in the 1) moderate (MOD), 2) lower heavy (HVY1), and 3) upper heavy-intensity (HVY2) domain; interval cycling in the form of 4) high-intensity interval training (HIIT) in the severe-intensity domain, or 5) sprint-interval training (SIT) in the extreme-intensity domain; or no exercise for 6) control (CON). All training groups, except SIT, were work-matched. Training participants completed three sessions per week for 6 wk with physiological evaluations performed at PRE, MID, and POST intervention. Compared with the change in V̇O 2max (∆V̇O 2max ) in CON (0.1 ± 1.2 mL·kg -1 ·min -1 ), all training groups, except MOD (1.8 ± 2.7 mL·kg -1 ·min -1 ), demonstrated a significant increase ( P < 0.05). HIIT produced the highest increase (6.2 ± 2.8 mL·kg -1 ·min -1 ) followed by HVY2 (5.4 ± 2.3 mL·kg -1 ·min -1 ), SIT (4.7 ± 2.3 mL·kg -1 ·min -1 ), and HVY1 (3.3 ± 2.4 mL·kg -1 ·min -1 ), respectively. The ΔPO at the estimated lactate threshold ( θLT ) was similar across HVY1, HVY2, HIIT, and SIT, which were all greater than CON ( P < 0.05). The ΔV̇O 2 and ΔPO at θLT for MOD was not different from CON ( P > 0.05). HIIT produced the highest ΔPO at maximal metabolic steady state, which was greater than CON, MOD, and SIT ( P < 0.05). This study demonstrated that i) exercise intensity is a key component determining changes in V̇O 2max and submaximal thresholds and ii) exercise intensity domain-based prescription allows for a homogenous metabolic stimulus across individuals.

Exercise training and vascular function in postmenopausal individuals: a systematic review and meta-analysis.

Cardiovascular disease (CVD) is a leading cause of morbidity and mortality for menopausal individuals. Flow-mediated dilation (FMD), a surrogate marker of CVD, improves with aerobic exercise training in healthy and nonhealthy cohorts. However, systematic evaluation and precise estimate of this effect for menopausal individuals are unknown. We conducted a systematic review with meta-analysis to evaluate the influence of exercise training on FMD in postmenopausal individuals. Studies were identified from systematic search of major electronic databases (PubMed, ScienceDirect, and Cochrane Library) from inception to February 2021. Healthy, postmenopausal individuals were included, following an aerobic exercise intervention assessing FMD. A random-effects meta-analysis was used to calculate a pooled effect size (mean difference [MD]) with 95% confidence interval. Heterogeneity was assessed using I2 statistics. Metaregression was used to assess the association between changes in FMD and physical characteristics (eg, blood pressure, age, baseline FMD) and intervention details (metabolic equivalents and change in maximal oxygen uptake [∆V˙ o2max ]). For variables that significantly correlated, a multiple metaregression model was used to assess the accounted variance in between-study ∆FMD%. Study quality was assessed using the National Heart, Lung, and Blood Institute assessment tool. Nine studies, including 11 interventions (6 controlled interventions and 5 pre-post interventions; N = 182), with age range of 52 ± 4 to 64 ± 7 years underwent quantitative pooling of data. Exercise training significantly improved ∆FMD% (MD, 0.99; 95% confidence interval, 0.46-1.52; P < 0.001). Between-study heterogeneity was large and statistically significant ( I2 = 93.8%, P < 0.001). Post hoc analysis based on study design identified significant heterogeneity in the MD in ∆FMD% between controlled and pre-post study interventions ( P < 0.05). According to multiple metaregression, diastolic and systolic blood pressure and ∆V˙ o2max significantly predicted ∆FMD% ( Q = 15.74, df = 3, P < 0.01, R2 = 0.72). Aerobic exercise training improves FMD for postmenopausal individuals, and this observation was greater among controlled versus pre-post interventions. A higher resting blood pressure and the greatest ∆V˙ o2max yielded the largest improvements in FMD.

Improved Aerobic Capacity and Adipokine Profile Together with Weight Loss Improve Glycemic Control without Changes in Skeletal Muscle GLUT-4 Gene Expression in Middle-Aged Subjects with Impaired Glucose Tolerance.

(1) Objective: The aim of this study was to clarify the role of adipokines in the regulation of glucose metabolism in middle-aged obese subjects with impaired glucose tolerance in response to a long-term exercise and dietary intervention. (2) Methods: Skeletal muscle, plasma and serum samples were examined in 22 subjects from an exercise–diet intervention study aiming to prevent type 2 diabetes. The subjects were further divided into two subgroups (non-responders n = 9 and responders n = 13) based on their achievement in losing at least 3 kg. (3) Results: The two-year exercise–diet intervention reduced leptin levels and increased adiponectin levels in responders; the changes in leptin levels were significantly associated with changes in their weights (r = 0.662, p < 0.01). In responders, insulin sensitivity (Bennett and McAuley index) increased and was associated with changes in maximal oxygen uptake (VO2peak) (r = 0.831, p < 0.010 and r = 0.890, p < 0.01). In addition, the VO2peak and oxidative capacity of skeletal muscle improved in responders, but not in non-responders. However, there were no changes between the two groups in expressions of the glucose transporter protein-4 (GLUT-4) gene or of AMP-activated protein kinase (AMPK)-α1 or AMPK-α2 proteins. (4) Conclusions: The exercise–diet intervention decreased serum leptin and increased serum adiponectin concentrations, improved glucose control without affecting GLUT-4 gene expression in the skeletal muscle in responders.

The ability of a submaximal cycle ergometer test to detect longitudinal changes in VO2max

BackgroundThe purpose of the present study was to examine the ability of a submaximal cycling test to detect longitudinal changes in maximal oxygen uptake (VO2max) and examine the conformity between changes in measured and estimated VO2max over a time span of 5–8 years.MethodsA total of 35 participants (21 men and 14 women), aged 29 to 63 years, performed the Ekblom-Bak (EB) submaximal cycle test for estimation of VO2max and a maximal treadmill running test for direct measurement of VO2max. The baseline tests were conducted between 2009 and 2012, and the follow-up tests were completed 5 to 8 years later. Pearson’s coefficient of correlation (r) and paired sample t-test were used to analyse the association between change in measured and estimated VO2max. Random and systematic errors between the measured and estimated VO2max were evaluated using Bland-Altman plots. Repeated measures ANOVA were used to test differences between changes over time.ResultsThere was no significant change in mean measured VO2max between baseline and follow-up (p = 0.91), however large individual variations were noted (− 0.78 to 0.61 L/min). The correlation between individual change in measured and estimated VO2max was r = 0.75 (p < 0.05), and the unstandardised B-coefficient from linear regression modelling was 0.88 (95% CI 0.61 to 1.15), i.e., for each litre of change in estimated VO2max, the measured value had changed 0.88 L. The correlation between baseline and follow-up errors (the difference between estimated-measured VO2max at each occasion) was r = 0.84 (p < 0.05). With regard to the testing procedure, repeated measures ANOVA revealed that there was no significant difference between the group who exercised at the same work rates at baseline and follow-up (n = 25), and those who required a change in work rate (n = 10).ConclusionsThe EB test detected a change in VO2max with reasonably good precision over a time span of 5–8 years. Further studies are needed to evaluate if the test can be used in clinical populations and in subjects with different medications.

A Systematic Review on Markers of Functional Overreaching in Endurance Athletes

The aim of this brief review was to present an overview of noninvasive markers in trained to professional endurance athletes that can reflect a state of functional overreaching. A systematic literature search was conducted in the PubMed, Scopus, and PsycINFO databases. After screening 380 articles, 12 research papers were included for the systematic review. Good consensus was found between the different papers in which noninvasive parameters were able to reflect a state of functional overreaching. Changes in power output (PO), heart rate (HR; [sub]maximal and HR recovery), rating of perceived exertion, and scores in the Daily Analysis of Life Demands for Athletes (DALDA) and/or Profile of Mood States (POMS) were shown to be able to reflect functional overreaching, whereas changes in maximal oxygen uptake and HR-variability parameters were not. Functional overreaching within a maximal performance test was characterized by a decrease in peak PO and a lower maximum HR, whereas a lower mean PO and a lower HR were observed during time trials. Changes in parameters during a standardized submaximal test when functionally overreached were characterized by a higher PO at a fixed HR or a lower HR at a fixed intensity, higher rating of perceived exertion, and a faster HR recovery. Although both the DALDA and POMS were able to reflect functional overreaching, the POMS was not able to differentiate this response from acute fatigue, which makes it unsuitable for accurately monitoring functional overreaching.

Task-Oriented Circuit Training as an Alternative to Ergometer-Type Aerobic Exercise Training after Stroke.

Moderate-intensity aerobic exercise training is an important treatment strategy to enhance functional recovery and decrease cardiometabolic risk factors after stroke. However, stroke related impairments limit access to ergometer-type exercise. The aims of the current study were (1) to evaluate whether our task-oriented circuit training protocol (intermittent functional training; IFT) could be used to sustain moderate-intensity aerobic workloads over a 10-week intervention period, and (2) to investigate its preliminary effects on cardiorespiratory fitness and metabolic profiles compared to constant-load ergometer-type exercise (CET). Forty chronic hemiparetic stroke survivors were randomized to receive 30 sessions of IFT or CET over ten weeks. Similar proportions of participants were randomized to IFT (7/19) and CET (9/18) sustained workloads associated with moderate-intensity aerobic exercise over the study period (p = 0.515). However, CET was associated with more substantial changes in maximal oxygen uptake (MD = 2.79 mL min−1 kg−1 CI: 0.84 to 4.74) compared to IFT (MD = 0.62 mL min−1 kg−1 CI: −0.38 to 1.62). Pre to post changes in C-reactive protein (−0.9 mg/L; p =0.017), short-term glycemia (+14.7 µmol/L; p = 0.026), and resting whole-body carbohydrate oxidation (+24.2 mg min−1; p = 0.046) were observed when considering both groups together. Accordingly, IFT can replicate the aerobic intensities sustained during traditional ergometer-type exercise training. More work is needed to evaluate the dose–response effects of such task-oriented circuit training protocols on secondary prevention targets across the continuum of stroke recovery.

Longitudinal changes in maximal oxygen uptake in adolescent girls and boys with different training backgrounds

The purpose of this study was to investigate the effects of high‐volume endurance training on the development of maximal oxygen uptake (VO2max) in physically active boys and girls between the ages of 12 and 15 years, using a longitudinal design. The children participated in organized training in sports clubs for an average of 7‐10 hours per week, with one group undertaking a high volume of endurance training (~7 hours per week; End boys, n = 23 and End girls, n = 17) and the other group having a primary focus on technical and tactical skill development, undertaking low volumes of endurance training (~1.6 hours per week; non‐End boys, n = 29 and non‐End girls, n = 9). VO2max and anthropometrics were assessed at age 12, 13, and 15. At age 12, VO2max was 58.9 (5.6), 65.5 (7.2), 56.5 (6.5), and 58.8 (7.9) mL·kg−1·min−1 in End girls, End boys, non‐End girls, and non‐End boys, respectively. Over the three years, there was no difference between the training groups in the development of VO2max independent of scaling. In boys, VO2max relative to body mass (BM) did not change from age 12 to 15, while VO2max tended to decrease relative to fat‐free mass (FFM). In girls, VO2max relative to BM decreased slightly from age 12 to 15, with no changes over the years relative to FFM. The present longitudinal study suggests that in growing active children during puberty, high volumes of systematic endurance training do not have an additional effect on VO2max compared with similar volume of training mainly aiming at developing motor skills.

Heterogeneity and incidence of non-response for changes in cardiorespiratory fitness following time-efficient sprint interval exercise training

Interindividual variability for training-induced changes in maximal oxygen uptake (VO2max) is well described following continuous aerobic and high-intensity interval training. Whether similar variability is observed following time-efficient sprint interval training with minimal training volume (i.e., reduced-exertion high-intensity interval training; REHIT) is unknown. We conducted a pooled analysis of n=117 (68 men) training participants (mean±SD: age: 30±10 y; VO2max: 34.8±7.5 ml·kg-1·min-1), who completed a VO2max assessment before and 3 days after 6 weeks of REHIT comprising of two 10-20 second 'all-out' cycling sprints per session, and n=40 no-intervention control participants (age: 30±13 y; VO2max: 31.5±6.5 ml·kg-1·min-1) who completed repeated VO2max tests over a comparable timeframe. Individual responses estimated using 50% confidence intervals derived from the technical error were interpreted against a smallest worthwhile change (SWC) of 1.75 ml·kg-1·min-1. The standard deviation of individual responses was 2.39 ml·kg-1·min-1 demonstrating clinically meaningful heterogeneity in training-induced changes in VO2max following REHIT that exceed the technical, biological and random within-subjects variability of VO2max assessment. The likely (75% probability) non-response rate was 18% (21/117), and 49% (57/117) of individuals demonstrated increases in VO2max likely higher than the SWC. We conclude that the well-described increase in VO2max following REHIT at the group level is subject to substantial variability in magnitude at an individual level. This has important implications for exercise prescription and can be harnessed to elucidate mechanisms of adaptation. Novelty: • There is substantial heterogeneity in VO2max responses following time-efficient sprint interval training • Proportion of non-response was 18% and ∽50% of individuals show clinically meaningful increases in VO2max.

Effects of Swimming-Specific Repeated-Sprint Training in Hypoxia Training in Swimmers.

The aim of this study was to investigate the effect of a 4 weeks in-water swimming-specific repeated-sprint training in hypoxia (RSH) compared to similar training in normoxia (RSN). Following a repeated-measures, counterbalanced cross-over design, 10 swimmers were requested to perform two trials consisting of in-water repeated sprints in hypoxic (RSH, simulated 4,040 m; FiO2 = 13.7%) or normoxic (RSN, 459 m, FiO2 calibrated = 20.9%) conditions. In both conditions, 8 additional exercise including 3 sets of 5 × 15 m “all-out” sprints (corresponding to a total of 625 m), with 20 s of passive recovery between efforts and 200 m of easy swimming between sets were included at the end of their swimming program over a 4 weeks period. Hypoxic condition was generated using a simulator pumping air with lowered oxygen concentration into a facial mask. An incremental maximal test on an ergocycle, as well as 100 m and 400 m freestyle swimming performance (real competition format) were assessed before (pre), 7 days (post-1), and 2 weeks (post-2) after intervention. During training, heart rate (HR) and oxygen saturation (SpO2) were monitored. RSH showed significantly lower SpO2 (70.1 ± 4.8% vs. 96.1 ± 2.7%, P < 0.01), concomitant with higher mean HR (159 ± 11 bmp vs. 141 ± 6 bmp, P < 0.01) than RSN. No significant changes in maximal oxygen uptake, other submaximal physiological parameters, 100 or 400 m swimming performances were found. Although providing additional physiological stress, performing in-water RSH does not provide evidence for higher benefits than RSN to improve swimmers performance.

Effects of an exercise intervention for patients with advanced inoperable lung cancer undergoing chemotherapy: A randomized clinical trial

ObjectiveExercise can improve treatment-related side effects, quality of life, and function in patients with various types of cancer; however, more evidence is needed for patients with advanced inoperable lung cancer. Material and methodsWe randomized 218 patients with advanced inoperable lung cancer to a 12-week supervised, structured exercise training program (aerobic, strength, and relaxation training) twice weekly versus usual care. Primary outcome was change in maximal oxygen uptake (VO2 peak). Secondary outcomes were muscle strength, functional capacity, forced expiratory volume in 1 s, health-related quality of life, anxiety, and depression. ResultsThere was no significant difference between the intervention and control groups in VO2 peak. There was a significant improvement in muscle strength. There was also a significant difference between the two for social well-being (Functional Assessment of Cancer Therapy—Lung, FACT-L), anxiety, and depression. ConclusionThere was a significant reduction in the level of anxiety and depression and a significant increase in all muscle strength outcomes in the intervention group compared to patients randomized to usual care. There was a significant difference between the groups for social well-being. The primary outcome did not show a significant improvement in VO2 peak. Based on our results, future patients with advanced inoperable lung cancer should be considered for supervised exercise during the course of their disease.

Predicting Changes in Maximal Oxygen Uptake in Response to Polarized Training (Sprint Interval Training, High-Intensity Interval Training, and Endurance Training) in Mountain Bike Cyclists.

Hebisz, R, Hebisz, P, Danek, N, Michalik, K, and Zatoń, M. Predicting changes in maximal oxygen uptake in response to polarized training (sprint interval training, high-intensity interval training, and endurance training) in mountain bike cyclists. J Strength Cond Res 36(6): 1726-1730, 2022-The aim of this study was to determine the predictors of change in maximal oxygen uptake (ΔV̇o2max) in response to a polarized training program. Twenty well-trained mountain bike cyclists completed an 8-week intervention of sprint interval training (SIT) (8-16 30-second maximal sprints), high-intensity interval training (4-6 bouts at 85-95% maximal aerobic power), and endurance training (2-3 hours cycling at 70-80% power at the ventilatory threshold). An incremental exercise test was performed to determine preintervention and postintervention maximal oxygen uptake (V̇o2max) and maximal pulmonary ventilation (VEmax) normalized to lean body mass (LBM). The frequency and time domain of heart rate variability (HRV) was also determined during recovery after moderate warm-up in the first and last SIT. Training status was quantified as the total distance cycled in the previous year. V̇o2max, VEmax, and the root mean square of the successive differences of normal-to-normal time interval between heartbeats (RMSSD), which is the time domain of HRV all increased significantly. Multiple significant correlations were observed between ΔV̇o2max and training status and baseline measures of VEmax·LBM-1, RMSSD, and V̇o2max·LBM-1 and a regression equation was developed (r = 0.87, r2 = 0.76; p = 0.0001). The change in V̇o2max in response to polarized training can be predicted with high accuracy based on several measurable variables.

The relationship between training load and fitness indices over a pre-season in professional soccer players.

An association between training load and changes in aerobic fitness has been established but the effect of training load on changes in strength/power remains controversial. Internal (Banister's TRIMP) and external (total distance, high-speed running and sprint distance) training load was collected from sixteen professional soccer players during and aerobic fitness and strength/power variables were measured before and after a 9-week pre-season. Banister's TRIMP had a moderate correlation with changes in maximal oxygen uptake (r=0.46, 90% CI: 0.04; 0.74). Total distance had a large and a moderate correlation with changes in velocity at 2M (r=0.60, 90% CI: 0.23; 0.82) and changes in velocity at 4M (r=0.42, 90% CI: -0.01; 0.72). High-speed running had moderate correlations with changes in maximal oxygen uptake (r=0.45, 90% CI: 0.03; 0.74), velocity at 2M (r=0.45, 90% CI: 0.03; 0.74) and velocity at 4M (r=0.39, 90% CI: -0.00; 0.70). Sprint distance had a large and a moderate correlation with changes in maximal oxygen uptake (r=0.58, 90% CI: 0.20; 0.81) and velocity at 4M (r=0.46, 90% CI: 0.00; 0.74 respectively). High versus low total distance was associated with lower changes in squat jump and countermovement jump (ES=-0.90, 90% CI: -1.57; -0.24 and ES=-1.06, 90% CI: -1.89; -0.24) respectively. High versus low high-speed running was associated with higher changes in maximal oxygen uptake (ES=0.36, 90% CI: 0.02; 0.70) but lower changes in squat jump (ES=-0.58, 90% CI: -1.32; 0.15). External rather internal training load had more pronounced correlations with changes in aerobic fitness. Higher compared with lower volumes of total distance and high-speed running were associated with lower gains in strength/power indices. Establishing a "dose-response" association between external/internal training load and endurance as well as strength adaptations, may maximize endurance gains with the least possible interference on strength/power gains, thus better informing soccer training practice.

Effectiveness of High-Intensity Interval Training Versus Moderate-Intensity Continuous Training in Hypertensive Patients: a Systematic Review and Meta-Analysis.

The purpose of this meta-analysis is to compare the effects of moderate-intensity continuous training (MICT) and high-intensity interval training (HIIT) on blood pressure of hypertensive individuals. Continuous aerobic training programs are successful in health promotion and are effective in systolic blood pressure (SBP) and diastolic blood pressure (DBP) modulation. However, HIIT seems to be superior to MICT to improvement of cardiorespiratory fitness. PubMed, ScienceDirect, and Google Scholar were searched for randomized clinical trials that compared chronic effects of HIIT and MICT on BP in hypertensive subjects. Pre- and post-intervention changes in maximal oxygen uptake (VO2max) between MICT and HIIT were analyzed. Both interventions presented significant differences in SBP (MICT: mean difference (MD), 3.7mmHg [95% CI = 2.57, 4.82], p < 0.00001; and HIIT: MD, 5.64mmHg [95% CI = 1.69, 9.52], p = 0.005) and in DBP (MICT: MD, 2.41mmHg [95% CI = 1.09, 3.72], p = 0.0003; and HIIT: MD, 4.8mmHg [95% CI = 2.9, 6.7], p < 0.00001) compared with the control group. No differences were found in the SBP values (MD, 1.13mmHg [95% CI = - 0.01, 2.27], p = 0.05); however, differences were found between groups in DBP (MD, 1.63mmHg [95% CI = 0.83, 2.44], p = 0.0001). In the secondary outcome, both interventions increased VO2max in comparison with control groups (MICT: MD, 1.30ml/kg/min [95% CI = 0.92, 1.68], p < 0.00001; and HIIT: MD, 4.90ml/kg/min [95% CI = 3.77, 6.04], p < 0.00001), and HIIT promoted greater improvement than MICT (MD, 2.52ml/kg/min [95% CI = 1.90, 3.13], p < 0.0001). In conclusion, HIIT and MICT promote reduction in SBP in adults with hypertension, and HIIT showed a greater magnitude in DBP reduction. For hypertensive patients, HIIT may be associated with a greater improvement in VO2max than MICT might.

Personalized Moderate-Intensity Exercise Training Combined with High-Intensity Interval Training Enhances Training Responsiveness.

This study sought to determine if personalized moderate-intensity continuous exercise training (MICT) combined with high-intensity interval training (HIIT) was more effective at improving comprehensive training responsiveness than MICT alone. Apparently healthy, but physically inactive men and women (n = 54) were randomized to a non-exercise control group or one of two 13-week exercise training groups: (1) a personalized MICT + HIIT aerobic and resistance training program based on the American Council on Exercise guidelines, or (2) a standardized MICT aerobic and resistance training program designed according to current American College of Sports Medicine guidelines. Mean changes in maximal oxygen uptake (VO2max) and Metabolic (MetS) z-score in the personalized MICT + HIIT group were more favorable (p < 0.05) when compared to both the standardized MICT and control groups. Additionally, on the individual level, there were positive improvements in VO2max (Δ > 4.9%) and MetS z-score (Δ ≤ −0.48) in 100% (16/16) of participants in the personalized MICT + HIIT group. In the present study, a personalized exercise prescription combining MICT + HIIT in conjunction with resistance training elicited greater improvements in VO2max, MetS z-score reductions, and diminished inter-individual variation in VO2max and cardiometabolic training responses when compared to standardized MICT.

Effects of various interval training regimes on changes in maximal oxygen uptake, body composition, and muscular strength in sedentary women with obesity.

We determined the effects of two high-intensity interval training (HIIT) regimens [the traditional (TRAD) and periodized (PER)] on changes in maximal oxygen uptake (VO2max), body composition, and muscular strength in sedentary, obese women. Seventeen women (age and BMI = 37.5 ± 10.5year and 39.1 ± 4.3kg/m2) were randomized into a 6week regime of TRAD or PER which consisted of three sessions per week, two in the laboratory, and one on their own. Pre- and post-training, VO2max, body composition, and muscular strength of the knee extensors (KE) and flexors (KF) were assessed via ramp cycling to exhaustion, air displacement plethysmography, and isokinetic dynamometry, respectively. VO2max was increased by 4-5% in response to training (p = 0.045) with no group-by-time interaction (p = 0.79). Body mass, fat mass, and waist-to-hip ratio were unaltered (p > 0.05) in response to training, yet there was a significant change in percent body fat (p = 0.03), percent fat-free mass (p = 0.03), and absolute fat-free mass (p = 0.03) in TRAD but not PER. No change occurred in KE (p = 0.36) or KF torque (p = 0.75) in response to training and there was no group-by-time interaction (p > 0.05). Low-volume HIIT improved VO2max and body composition but did not modify muscular strength, which suggests that obese women desiring to increase strength should initiate more intense HIIT or partake in formal resistance training.

Bicycle usage among inactive adults provided with electrically assisted bicycles

In the present study we aimed primarily to examine cycling time and distance when inactive subjects were provided with electrically assisted bicycles. Secondly to evaluate changes in maximal oxygen uptake. Inactive employees in a selection of public and private corporations in three Norwegian cities were invited to participate. Inclusion criteria were: a desire to cycle to work, residence more than 3 km from the workplace, and not physically active according to guidelines. There were 25 participants in the study and we provided them all with electrically assisted bicycles fitted with GPS bike computers to record usage. The participants were followed for three to eight months, 226 days on average. Measures of maximal oxygen uptake were performed before and after the intervention. Demographic characteristics and prior transportation habits were reported in a questionnaire at baseline. Participants cycled for 107.1± 62 min per week covering 37.6 ± 24 km per week. The distances cycled were significantly greater in the autumn (47.4 km/week, p=0.035) than in the spring (32.1 km/week). Participants cycled more on weekdays (7.1 km/day, p &lt; 0.001) compared to weekends (0.9 km/day, p&lt;0.001). Maximal oxygen uptake improved significantly, 2.4 ml/min/kg (7.7 %), p&lt;0.001 and this was associated with cycling distance (r=0.49, p=0.042) and self-reported commuting distance (r=0.51, p=0.018). Offering electrically assisted bicycles to inactive employees may initiate transport-related physical activity and may give positive health effects.

Regulation of Red Blood Cell Volume with Exercise Training.

Hypervolemia is a hallmark of endurance training (ET) and manifests by similar elevations in plasma (PV) and red blood cell volume (RBCV) so that hematocrit largely remains unaltered following weeks/months of training. While the mechanisms facilitating PV expansion with ET have been previously reviewed extensively this is not the case for RBCV. Endurance champions may have 40% more RBCV than controls and RBCV may increase up to 10% following months of regular exercise training in healthy individuals. Such adaptations are the main factor leading to concomitant changes in maximal oxygen uptake. The increase in RBCV is preceded by that of PV after few ET sessions, which in turn transiently decreases the hematocrit. The "critmeter" theory suggests that O2 sensors located within the juxtamedullary apparatus regulate the hematocrit via modulation of renal erythropoietin (EPO) production according to arterial O2 content-dependent changes in tissue O2 pressure. Hence, the initial decrease in hematocrit can be considered as a primary mechanism facilitating RBCV expansion with ET. Furthermore, after a single endurance exercise bout blood volume-regulating hormones ANGII and VPN increase transiently. Both stimulate renal EPO production. Catecholamines and cortisol, stress hormones acutely increased by endurance exercise, may facilitate the release of red blood cells from the bone marrow, thus possibly contributing to ET-induced erythropoiesis. These and other endocrine effects could be enhanced by the hyperplasia of the hematopoietic bone marrow observed in endurance athletes. © 2019 American Physiological Society. Compr Physiol 9:149-164, 2019.

Change In VO2max And Time Trial Performance To Interval Training Prescribed According To Ventilatory Threshold

Research shows that about 20 % of participants demonstrate no change in maximal oxygen uptake (VO2max) in response to moderate intensity continuous training (MICT) (Bouchard et al 1999) or high intensity interval training (HIIT, Astorino & Schubert 2014). Approximately 50 % of this non-response is hereditary (Bouchard et al 1999) although the other 50 % is unexplored (Mann et al. 2015) and likely related to participants’ habitual physical activity and dietary patterns, sleep, and traits of the training regime. In unfit adults, Wolpern et al. (2015) showed that MICT prescribed according to Ventilatory Threshold (VT) led to lower onset of individual non-response than when prescribed using HR. PURPOSE: To prescribe HIIT according to VT to monitor aggregate and individual responses in both VO2max and time trial (TT) performance. METHODS: Eleven active (age and VO2max = 28.9 ± 7.9 yr and 38.4 ± 4.5 mL/kg/min) men and women performed baseline testing including a VO2max test on a cycle ergometer to determine peak power output (PPO) and ventilatory threshold (Caiozzo et al. 1986). Each subject also performed a 8.2 km cycling TT over three separate trials. Over a 3 wk period, they underwent 9 d of HIIT consisting of 8 – 10 60 s bouts at work rate of 130% VT with a 75 s active recovery period. Training elicited an intensity = 89.2 ± 5.7 %PPO. VO2max and TT were assessed within 96 h after training. Controls (CON) (n=6, age and VO2max = 22.7 ± 2.3 yr and 40.4 ± 8.7 mL/kg/min) consisted of active individuals who completed two sessions of baseline testing separated by 3 wk. RESULTS: Data showed a significant groupXtime interaction for VO2max (38.4 ± 4.5 mL/kg/min to 40.7 ± 4.8 mL/kg/min vs. 40.4 ± 8.7 mL/kg/min to 40.6 ± 8.7 mL/kg/min, p=0.017) and TT (923.1 ± 78.2 s to 899.4 ± 67.2 s vs. 921.2 ± 115.0 s to 924.3 114.4 s, p=0.007) between HIIT and CON. With 2Xtypical error = 0.11 L/min for VO2max and 18.0 s for TT, 63 % of participants showed meaningful increases in VO2max and TT in response to this low dose of HIIT. Two of 11 participants exhibited non-response in both variables. CONCLUSION: These preliminary data show that 9 d of HIIT at 130 %VT significantly increases VO2max and TT performance, but these responses do not occur in everyone. It is possible that the volume or duration of HIIT used is inadequate to promote greater responses in habitually active individuals.