Efficacy of different 8 h time-restricted eating schedules on visceral adipose tissue and cardiometabolic health: A study protocol.

BACKGROUND AND AIMS: To investigate the efficacy and feasibility of three different 8 h time-restricted eating (TRE) schedules (i.e., early, late, and self-selected) compared to each other and to a usual-care (UC) intervention on visceral adipose tissue (VAT) and cardiometabolic health in men and women. METHODS AND RESULTS: Anticipated 208 adults (50% women) aged 30-60 years, with overweight/obesity (25 ≤ BMI<40 kg/m2) and with mild metabolic impairments will be recruited for this parallel-group, multicenter randomized controlled trial. Participants will be randomly allocated (1:1:1:1) to one of four groups for 12 weeks: UC, early TRE, late TRE or self-selected TRE. The UC group will maintain their habitual eating window and receive, as well as the TRE groups, healthy lifestyle education for weight management. The early TRE group will start eating not later than 10:00, and the late TRE group not before 13:00. The self-selected TRE group will select an 8 h eating window before the intervention and maintain it over the intervention. The primary outcome is changes in VAT, whereas secondary outcomes include body composition and cardiometabolic risk factors. CONCLUSION: This study will determine whether the timing of the eating window during TRE impacts its efficacy on VAT, body composition and cardiometabolic risk factors and provide insights about its feasibility.

Sex-specific dose-response effects of a 24-week supervised concurrent exercise intervention on cardiorespiratory fitness and muscular strength in young adults: The ACTIBATE randomized controlled trial.

Concurrent training has been postulated as an appropriate time-efficient strategy to improve physical fitness, yet whether the exercise-induced adaptations are similar in men and women is unknown. An unblinded randomized controlled trial was conducted to investigate sex-specific dose-response effects of a 24-week supervised concurrent exercise training program on cardiorespiratory fitness and muscular strength in young adults. One hundred and forty-four sedentary adults aged 18-25 years were assigned to either (i) a control group (n = 54), (ii) a moderate intensity exercise group (MOD-EX, n = 46), or (iii) a vigorous intensity exercise group (VIG-EX, n = 44) by unrestricted randomization. Cardiorespiratory fitness (VO2max ), hand grip strength, and one-repetition maximum of leg press and bench press were evaluated at baseline and after the intervention. A total of 102 participants finished the intervention (Control, n = 36; 52% women, MOD-EX, n = 37; 70% women, and VIG-EX, n = 36; 72% women). In men, VO2max significantly increased in the MOD-EX (~8%) compared with the control group and in the VIG-EX group after the intervention (~6.5%). In women, VO2max increased in the MOD-EX and VIG-EX groups (~5.5%) compared with the control group after the intervention. There was a significant increment of leg press in the MOD-EX (~15.5%) and VIG-EX (~18%) groups compared with the control group (~1%) in women. A 24-week supervised concurrent exercise was effective at improving cardiorespiratory fitness and lower body limbs muscular strength in young women-independently of the predetermined intensity-while only at moderate intensity improved cardiorespiratory fitness in men.

Mechanisms underlying the health benefits of intermittent hypoxia conditioning.

Intermittent hypoxia (IH) is commonly associated with pathological conditions, particularly obstructive sleep apnoea. However, IH is also increasingly used to enhance health and performance and is emerging as a potent non-pharmacological intervention against numerous diseases. Whether IH is detrimental or beneficial for health is largely determined by the intensity, duration, number and frequency of the hypoxic exposures and by the specific responses they engender. Adaptive responses to hypoxia protect from future hypoxic or ischaemic insults, improve cellular resilience and functions, and boost mental and physical performance. The cellular and systemic mechanisms producing these benefits are highly complex, and the failure of different components can shift long-term adaptation to maladaptation and the development of pathologies. Rather than discussing in detail the well-characterized individual responses and adaptations to IH, we here aim to summarize and integrate hypoxia-activated mechanisms into a holistic picture of the body's adaptive responses to hypoxia and specifically IH, and demonstrate how these mechanisms might be mobilized for their health benefits while minimizing the risks of hypoxia exposure.

Training zones through muscle oxygen saturation during a graded exercise test in cyclists and triathletes.

Use of muscle oxygen saturation (SmO2) has been validated as a performance factor during incremental exercise with portable near-infrared stereoscopy (NIRS) technology. However, there is little knowledge about the use of SmO2 to identify training zones. The objective of this study was to evaluate the metabolic zones by SmO2: maximum lipid oxidation zone (Fatmax), ventilatory thresholds (VT1 and VT2) and maximum aerobic power (MAP) during a graded exercise test (GXT). Forty trained cyclists and triathletes performed a GXT. Output power (W), heart rate (HR), oxygen consumption (VO2), energy expenditure (kcal/min) and SmO2 were measured. Data were analysed using the ANOVA test, ROC curves and multiple linear regressions. Significance was established at p ≤ 0.05. SmO2 decreases were observed from baseline (LB) to Fatmax (Δ = -16% p < 0.05), Fatmax to VT1 (Δ = -16% p < 0.05) and VT1 to VT2 (Δ = -45% p < 0.01). Furthermore, SmO2 together with weight, HR and output power have the ability to predict VO2 and energy expenditure by 89% and 90%, respectively. We conclude that VO2 and energy expenditure values can be approximated using SmO2 together with other physiological parameters and SmO2 measurements can be a complementary parameter to discriminate aerobic workload and anaerobic workload in athletes.

Acute physiological response to a normobaric hypoxic exposure: sex differences.

Although preliminary studies suggested sex-related differences in physiological responses to altitude/hypoxia, controlled studies from standardised exposures to normobaric hypoxia are largely lacking. Hence, the goals of this study were to provide information on cardiorespiratory responses to a 7-h normobaric hypoxia exposure and to explore potential differences between men and women. In this crossover study, a total of 15 men and 14 women were subjected to a 7-h exposure in normoxia (FiO2: 21%) and normobaric hypoxia (FiO2: 15%). Values of peripheral oxygen saturation, heart rate, systolic and diastolic blood pressure and respiratory gases were recorded every hour (8 time points), and oxygen saturation every 30 min (15 time points). Compared to normoxia, exposure to hypoxia significantly increased minute ventilation from baseline to hour 7 in males (+ 71%) and females (+ 40%), significantly greater in men (p < 0.05). A steeper decrease in peripheral oxygen saturation until 2.5 h in hypoxia was seen in females compared to males (p < 0.05). In conclusion, the ventilatory response to hypoxia was more pronounced in men compared to women. Moreover, during the first hours in hypoxia, peripheral oxygen saturation dropped more markedly in women than in men, likely due an initially lower and/or less efficient ventilatory response to moderate hypoxia. Those findings should be considered when performing interventions for therapy or prevention in normobaric hypoxia. Nevertheless, further large-scaled and well-controlled studies are needed.

Haematological responses to repeated sprints in hypoxia across different sporting modalities.

The aim was to determine the effects of repeated-sprint training in hypoxia on haematocrit and haemoglobin in different sporting modalities. Seventy-two participants were randomly allocated to Active-Repeated sprint in hypoxia (A-RSH, n= 8); Active-Repeated sprint in normoxia (A-RSN, n= 8); Active-Control (A-CON, n= 8); Team Sports-RSH (T-RSH, n= 8); Team Sports-RSN (T-RSN, n= 8); Team Sports-Control (T-CON, n= 8); Endurance-RSH (E-RSH, n= 8); Endurance-RSN (E-RSN, n= 8); Endurance-Control (E-CON, n= 8). Sessions consisted of two sets of five sprints of 10 swith recovery of 20 sbetween sprints and 10 min between sets. Blood samples for haematocrit and haemoglobin concentrations were obtained before and after, and 2 weeks after cessation. Haematocrit and haemoglobin were lower for the E-RSN group following 2 weeks of cessation of protocol compared with E-RSH (p = 0.035) and E-CON (p = 0.045). Haematocrit of the A-RSH group was higher compared with baseline (p = 0.05) and Post (p = 0.05). Similarly, the T-RSH group demonstrated increases in haematocrit following 2 weeks of cessation compared with Post (p = 0.04). Repeated Sprint Training in Hypoxia had different haematological effects depending on sporting modality.

Effects of 7-day intake of hydrogen-rich water on physical performance of trained and untrained subjects.

Hydrogen-rich water (HRW) is used as a supplement to improve performance and reduce fatigue in athletes. However, the potentially beneficial effects of HRW intake could be mediated by the training status of athletes. The purpose of the study was to analyse the ergogenic effect of intake of HRW for one week on aerobic and anaerobic performance, both in trained and untrained individuals. Thirty-seven volunteers participated in the study and were divided into two experimental groups: trained cyclists and untrained subjects. A double-blind crossover design was performed in which all subjects took a placebo (PW) and nano-bubble HRW (pH: 7.5; hydrogen concentration: 1.9 ppm; oxidation-reduction potential (ORP): -600 mV). At the end of 7-day intake, performance was assessed by an incremental VO2max test and by a maximum anaerobic test. After HRW intake, only trained cyclists improved their performance in the anaerobic test with an increase in peak power (from 766.2 ± 125.6 to 826.5 ± 143.4 W; d = .51) and mean power (from 350.0 ± 53.5 to 380.2 ± 71.3 W; d = .51), and a decrease in the fatigue index (from 77.6 ± 5.8 to 75.1 ± 5.9%; d = .45). The findings demonstrate that the ergogenic effect of HRW is mediated by the training status, and that 7-day intake of HRW would be an effective strategy for improving anaerobic performance in trained cyclists.

Repeated sprint in hypoxia as a time-metabolic efficient strategy to improve physical fitness of obese women.

PURPOSE: To investigate the training and detraining effects of two different hypoxic high-intensity protocols on cardiorespiratory fitness, maximal fat oxidation and energy contribution in obese women. METHODS: 82 obese women completed a 12-week training of: (1) interval training in hypoxia (IHT; n = 19; 3 min at 90%Wmax: 3 min at 55-65%Wmax; FiO2 = 17.2%), (2) interval training in normoxia (INT; n = 20; 3 min at 90%Wmax: 3 min at 55-65%Wmax), (3) repeated sprint training in hypoxia (RSH; n = 22; 30 s at 130%Wmax: 3 min at 55-65%Wmax; FiO2 = 17.2%), and (4) repeated sprint training in normoxia (RSN; n = 21; 30 s at 130%Wmax: 3 min at 55-65%Wmax). VO2max, workload, time to exhaustion and heart rate were assessed at baseline, after completion of 36 training sessions over 12 weeks and after 4 weeks of detraining. RESULTS: Hypoxic training (IHT and RSH) showed a significant positive effect on absolute (p < 0.001) and relative maximal oxygen uptake (p < 0.001) as well as VT2 (%VO2max; p < 0.001). Both IHT and RSH showed significantly higher values of absolute VO2max (IHT: + 26.63%; RSH: + 19.79%) and relative VO2max (IHT: + 27.95%; RSH: + 19.94%) between baseline and post-exercise (p < 0.001). VO2max (IHT: + 21.74%; RSH: + 17.65%) and relative VO2max (IHT: + 23.53%; RSH: + 17.15%) remained significantly higher after detraining in IHT and RSH (p < 0.001). CONCLUSION: A larger improvement in cardiorespiratory fitness has been observed after high-intensity interval training under normobaric hypoxia. As interval training or repeated sprint training did not show a significant effect, RSH might provide a time-metabolic effective strategy in this population.

Effects of whole-body vibration under hypoxic exposure on muscle mass and functional mobility in older adults.

BACKGROUND: Ageing is accompanied by a loss of muscle mass and function, which are associated with decrease of functional capacity. Combination of WBV training with normobaric hypoxic exposure could augment the beneficial effects due to synergic effects of both treatments. AIMS: The purpose of this study was to examine the effects of 36 sessions of the combined WBV training and normobaric hypoxic exposure on muscle mass and functional mobility in older adults. METHODS: Nineteen elderly people were randomly assigned to a: vibration normoxic exposure group (NWBV; n = 10; 20.9% FiO2) and vibration hypoxic exposure group (HWBV; n = 9). Participants developed 36 sessions of WBV training along 18 weeks, which included 4 bouts of 30 s (12.6 Hz in frequency and 4 mm in amplitude) with 60 s of rest between bouts, inside a hypoxic chamber for the HWBV. The "Timed Up and Go Test" evaluated functional mobility. Percentages of lean mass were obtained with dual-energy X-ray absorptiometry. RESULTS: Neither statistically significant within group variations nor statistically significant differences between both groups were detected to any parameter. DISCUSSION: Baseline characteristics of population, training protocol and the level of hypoxia employed could cause different adaptations on muscle mass and function. CONCLUSIONS: The combination of WBV training and hypoxic exposure did not cause any effect on either legs lean mass or functional mobility of older adults.

Fatigue Increases in Resting Muscle Oxygen Consumption after a Women's Soccer Match.

Currently, near infrared spectroscopy has a clear potential to explain the mechanisms of fatigue by assessing muscle oxygenation. The objective of the study was to observe the changes in muscle oxygen consumption after an official women's soccer match. The sample was 14 players who competing in the second division of Spain of women's soccer. They were evaluated before, immediately after and 24 h after the official match. Biochemical parameters were measured in blood plasma (BUN, GOT, LDH, CPK). The jumping in countermovement, perceived exertion and perceived muscle pain were also assessed. The muscle oxygen consumption and muscle oxygen saturation were evaluated in the gastrocnemius muscle with an arterial occlusion test. ANOVA of repeated measures, Pearson's correlation and Hopkins' statistics were applied to measure the magnitudes of change and effect size. There was observed an increase in kinetics of SmO2 at 24 h after the official match, using arterial occlusion. In addition, it was found that the increase in muscle oxygenation correlated with fatigue indicators, such as the increases in LDH, perceived muscle pain and the decrease in countermovement. It is confirmed that a women's soccer match produced an increase of resting muscle oxygenation in 24 h after the official match.

Detraining effect on overweight/obese women after high-intensity interval training in hypoxia.

PURPOSE: Promising benefits on fat mass and biochemical components may be reported after applying programs of cyclic hypoxia and HIIT. AIM: To investigate the effect of a month of detraining on cardiometabolic risk markers after active hypoxia exposure. METHODS: Participants included 59 overweight/obese women, who started a 12-week program of 36 sessions, and were randomly divided into four groups: (a) aerobic interval training in hypoxia (AitH; FiO2  = 17.2%; n = 13), (b) aerobic interval training in normoxia (AitN; n = 15), (c) sprint interval training in hypoxia (SitH; FiO2  = 17.2%; n = 15), and (d) sprint interval training in normoxia (SitN; n = 18). Body composition, anthropometric, and biochemical parameters were assessed at baseline (A), after 36 training sessions (B) and after 4 weeks of detraining (C). RESULTS: Hypoxia conditions showed a significant positive effect on waist circumference (P = 0.01), WHR (P = 0.04), and percentage of trunk fat mass (P < 0.001). The percentage of trunk fat continued to decrease significantly after training cessation in both AitH and SitH groups. CONCLUSION: After 4 weeks of detraining with a previous 12 weeks of high-intensity interval training under cyclic normobaric hypoxia, the percentage of fat mass located in the trunk decreases significantly and this effect was not observed in the normoxia groups.

Effects training in hypoxia on cardiometabolic parameters in obese people: A systematic review of randomized controlled trial.

OBJECTIVE: The aim of the present review is to evaluate effects of intermittent hypoxia and exercise therapy in cardiometabolic parameters on adult obese people. DATABASE: Three well-known databases were selected: EMBASE, MEDLINE and Web of Science. Studies selection: Inclusion criteria were: (a) human healthy overweight or obese adults, (b) study randomized controlled trial, (c) original experimental study, (d) English languages and (e) therapy with intermittent hypoxia and exercise. DESIGN: The assessment of the methodological quality of each study was based upon the risk of bias (PEDro scale) and level of evidence (CBO Guidelines). DATA EXTRACTION: five articles clearly met inclusion criteria and were reviewed to data extraction. RESULTS: In the hypoxia groups, weight, body mass index, waist circumference, waist-hip ratio, fat mass and lean mass improved in at least two studies in comparison with the baseline. Systolic blood pressure improved in one study. The lipid profile and the aerobic capacity were not reduced significantly. CONCLUSIONS: Results suggest that combined hypoxia with exercise may help to improve cardiometabolic parameters in obese people.

48-hour recovery of biochemical parameters and physical performance after two modalities of CrossFit workouts.

CrossFit is high-intensity interval training involving routines called 'workouts of the day' (WOD). The aim of the present study is to analyse biochemical parameters and physical performance after two modalities of CrossFit WODs, and to evaluate 48-hour recovery. Twelve trained CrossFit practitioners (age: 30.4 ± 5.37 years; VO2max: 47.8 ± 3.63 ml/min/kg; 1RM Power Clean: 93.2 ± 7.62 kg) participated in the study. A crossover design was applied, and participants completed two modalities of WODs on separate days: WOD1 (as many rounds as possible) and WOD2 (rounds for time). Blood lactate, ratings of perceived exertion and heart rate were measured to determine the intensity of training sessions. Biochemical parameters and physical performance were evaluated before, immediately after, 24 hours after and 48 hours after exercise. There were significant differences in intensity between WOD1 and WOD2 (lactate: 13.3±1.87 vs. 18.38±2.02 mmol/L, heart rate mean: 127.6±11.1 vs. 159.8±12.1 bpm), and blood glucose concentrations were significantly higher after WOD2 (135.4 ± 19.6 vs. 167.4±19.6 mg/dL). After exercise, WOD1 and WOD2 caused significant increases of hepatic transaminases, creatine phosphokinase and blood glucose, as well as a large decrease in the physical performance evaluated by the plank test. All these values returned to baseline by 48 hours after exercise. Both WODs caused metabolic and muscular stress, as well as a decrease in physical performance. All the levels recovered at 48 hours, so the stress caused by CrossFit WODs did not induce a pathological state.

Intermittent Hypoxic Training Increases and Prolongs Exercise Benefits in Adult Untrained Women.

Alba Camacho-Cardenosa, Marta Camacho-Cardenosa, Johannes Burtscher, Pedro R. Olivares, Guillermo Olcina, and Javier Brazo-Sayavera. Intermittent hypoxic training increases and prolongs exercise benefits in adult untrained women. High Alt Med Biol. 00:00-00, 2024. Background: Exercising in hypoxia may confer multiple health benefits, but the evidence for specific benefits is scarce. Methods: We investigated effects of intermittent hypoxic training (IHT) on the quality of life and functional fitness of healthy adult women, in a double-blind, randomized, placebo-controlled study. Subjects performed 36 sessions of IHT (experimental group, n = 41; fraction of inspired oxygen [FIO2]: 0.17) or the same training in normoxia (control group, n = 41; FIO2: 0.21). Health-related quality of life, fitness tests, and hemoglobin levels were assessed before (T1), directly after (T2), and 4 weeks after (T3) cessation. Results: At T2, upper body strength (+14.96%), lower body strength (+26.20%), and agility (-4.94%) increased significantly in the experimental group compared to baseline but not in controls. The experimental group improved lower body strength more (by 9.85%) than controls at T2 and performed significantly better in walking (by 2.92%) and upper body strength testing (by 16.03%), and agility (by 4.54%) at T3. Perceived general health and vitality was significantly greater in the experimental group at T2 and T3 compared with T1. None of these improvements were observed in the control group. Conclusions: IHT is a promising strategy to induce long-lasting fitness benefits in healthy adult women.

Impact of lifestyle moderate-to-vigorous physical activity timing on glycemic control in sedentary adults with overweight/obesity and metabolic impairments.

OBJECTIVE: Moderate-to-vigorous physical activity (MVPA) improves glucose levels; however, whether its timing affects daily glycemic control remains unclear. This study aims to investigate the impact of lifestyle MVPA timing on daily glycemic control in sedentary adults with overweight/obesity and metabolic impairments. METHODS: A total of 186 adults (50% women; age, 46.8 [SD 6.2] years) with overweight/obesity (BMI, 32.9 [SD 3.5] kg/m2) and at least one metabolic impairment participated in this cross-sectional study. MVPA and glucose patterns were simultaneously monitored over a 14-day period using a triaxial accelerometer worn on the nondominant wrist and a continuous glucose-monitoring device, respectively. Each day was classified as "inactive" if no MVPA was accumulated; as "morning," "afternoon," or "evening" if >50% of the MVPA minutes for that day were accumulated between 0600 and 1200, 1200 and 1800, or 1800 and 0000 hours, respectively; or as "mixed" if none of the defined time windows accounted for >50% of the MVPA for that day. RESULTS: Accumulating >50% of total MVPA during the evening was associated with lower 24-h (mean difference [95% CI], -1.26 mg/dL [95% CI: -2.2 to -0.4]), diurnal (-1.10 mg/dL [95% CI: -2.0 to -0.2]), and nocturnal mean glucose levels (-2.16 mg/dL [95% CI: -3.5 to -0.8]) compared with being inactive. This association was stronger in those participants with impaired glucose regulation. The pattern of these associations was similar in both men and women. CONCLUSIONS: These findings suggest that timing of lifestyle MVPA is significant. Specifically, accumulating more MVPA during the evening appears to have a beneficial effect on glucose homeostasis in sedentary adults with overweight/obesity and metabolic impairments.

Time-restricted eating and supervised exercise for improving hepatic steatosis and cardiometabolic health in adults with obesity: protocol for the TEMPUS randomised controlled trial.

INTRODUCTION: Metabolic dysfunction-associated steatotic liver disease is a major public health problem considering its high prevalence and its strong association with extrahepatic diseases. Implementing strategies based on an intermittent fasting approach and supervised exercise may mitigate the risks. This study aims to investigate the effects of a 12-week time-restricted eating (TRE) intervention combined with a supervised exercise intervention, compared with TRE or supervised exercise alone and with a usual-care control group, on hepatic fat (primary outcome) and cardiometabolic health (secondary outcomes) in adults with obesity. METHODS AND ANALYSIS: An anticipated 184 adults with obesity (50% women) will be recruited from Granada (south of Spain) for this parallel-group, randomised controlled trial (TEMPUS). Participants will be randomly designated to usual care, TRE alone, supervised exercise alone or TRE combined with supervised exercise, using a parallel design with a 1:1:1:1 allocation ratio. The TRE and TRE combined with supervised exercise groups will select an 8-hour eating window before the intervention and will maintain it over the intervention. The exercise alone and TRE combined with exercise groups will perform 24 sessions (2 sessions per week+walking intervention) of supervised exercise combining resistance and aerobic high-intensity interval training. All participants will receive nutritional counselling throughout the intervention. The primary outcome is change from baseline to 12 weeks in hepatic fat; secondary outcomes include measures of cardiometabolic health. ETHICS AND DISSEMINATION: This study was approved by Granada Provincial Research Ethics Committee (CEI Granada-0365-N-23). All participants will be asked to provide written informed consent. The findings will be disseminated in scientific journals and at international scientific conferences. TRIAL REGISTRATION NUMBER: NCT05897073.

Inter-set rest configuration effect on acute physiological and performance-related responses to a resistance training session in terrestrial vs simulated hypoxia.

Background: Metabolic stress is considered a key factor in the activation of hypertrophy mechanisms which seems to be potentiated under hypoxic conditions.This study aimed to analyze the combined effect of the type of acute hypoxia (terrestrial vs simulated) and of the inter-set rest configuration (60 vs 120 s) during a hypertrophic resistance training (RT) session on physiological, perceptual and muscle performance markers. Methods: Sixteen active men were randomized into two groups based on the type of hypoxia (hypobaric hypoxia, HH: 2,320 m asl; vs normobaric hypoxia, NH: FiO2 of 15.9%). Each participant completed in a randomly counterbalanced order the same RT session in four separated occasions: two under normoxia and two under the corresponding hypoxia condition at each prescribed inter-set rest period. Volume-load (load × set × repetition) was calculated for each training session. Muscle oxygenation (SmO2) of the vastus lateralis was quantified during the back squat exercise. Heart rate (HR) was monitored during training and over the ensuing 30-min post-exercise period. Maximal blood lactate concentration (maxLac) and rating of perceived exertion (RPE) were determined after the exercise and at the end of the recovery period. Results: Volume-load achieved was similar in all environmental conditions and inter-set rest period length did not appreciably affect it. Shorter inter-set rest periods displayed moderate increases in maxLac, HR and RPE responses in all conditions. Compared to HH, NH showed a moderate reduction in the inter-set rest-HR (ES > 0.80), maxLac (ES > 1.01) and SmO2 (ES > 0.79) at both rest intervals. Conclusions: Results suggest that the reduction in inter-set rest intervals from 120 s to 60 s provide a more potent perceptual, cardiovascular and metabolic stimulus in all environmental conditions, which could maximize hypertrophic adaptations in longer periods of training. The abrupt exposure to a reduced FiO2 at NH seems to reduce the inter-set recovery capacity during a traditional hypertrophy RT session, at least during a single acute exposition. These results cannot be extrapolated to longer training periods.

Resistance circuit training combined with hypoxia stimulates bone system of older adults: A randomized trial.

PURPOSE: Aging leads to gradual irreversible decline in bone mass. As adherence to pharmacological treatment is poor, hypoxia combined with strength training has been suggested for therapeutic benefit for clinical populations. The present study investigated the effects of normobaric cyclic hypoxic exposure combined with resistance circuit training on bone of older adults. METHODS: Healthy older adults (n = 50) were randomly assigned to a (1) control group (CON; n = 20), who were instructed to continue with their normal daily activities, (2) a group that performed resistance training in normoxia (RTN; n = 17) and (3) a group that performed resistance training in hypoxia (RTH; n = 13). During 24 weeks, RTH group performed resistance training with elastic bands under normobaric hypoxic conditions (16.1 % FiO2). A session of both exercise groups included nine exercises of several body areas with a structure of 3 sets × 12-15 repetitions per exercise, with a 1-minute rest between sets. Bone mineral density (g·cm-2) was measured using dual-energy X-ray absorptiometry. Bone turnover markers of formation (N-terminal propeptide of type I procollagen; PINP) and resorption (C-terminal telopeptide of type I collagen; bCTX) were analysed with enzyme-linked immunosorbent assay (ELISA) microplate reader. RESULTS: Values of bCTX and bCTX/PINP significant decreased in RTN (bCTX: 47.79 %; p = 0.002; bCTX/PINP: 61.43 %; p = 0.007) and RTH (bCTX: 59.09 %; p = 0.001; bCTX/PINP: 62.61 %; p = 0.003) groups compared with CON group. Change in bone mineral density was not significantly different between groups. Based on clinically significant change, 23 % of the participants in the RTH group reached this value for femoral neck and trochanter bone mineral density (vs 0 % and 6 % of the RTN group, respectively). CONCLUSIONS: 24-Weeks of normobaric cyclic hypoxic exposure combined with resistance circuit training has potential to generate positive effects on bone in older adults. TRIAL REGISTRATION NUMBER: NCT04281264 (date of registration: February 24, 2020).

Effectiveness, implementation, and monitoring variables of intermittent hypoxic bicycle training in patients recovered from COVID-19: The AEROBICOVID study.

Hypoxic exposure is safely associated with exercise for many pathological conditions, providing additional effects on health outcomes. COVID-19 is a new disease, so the physiological repercussions caused by exercise in affected patients and the safety of exposure to hypoxia in these conditions are still unknown. Due to the effects of the disease on the respiratory system and following the sequence of AEROBICOVID research work, this study aimed to evaluate the effectiveness, tolerance and acute safety of 24 bicycle training sessions performed under intermittent hypoxic conditions through analysis of peripheral oxyhemoglobin saturation (SpO2), heart rate (HR), rate of perceived exertion (RPE), blood lactate concentration ([La-]) and symptoms of acute mountain sickness in patients recovered from COVID-19. Participants were allocated to three training groups: the normoxia group (GN) remained in normoxia (inspired fraction of O2 (FiO2) of ∼20.9%, a city with 526 m altitude) for the entire session; the recovery hypoxia group (GHR) was exposed to hypoxia (FiO2 ∼13.5%, corresponding to 3,000 m altitude) all the time except during the effort; the hypoxia group (GH) trained in hypoxia (FiO2 ∼13.5%) throughout the session. The altitude simulation effectively reduced SpO2 mean with significant differences between groups GN, GHR, and GH, being 96.9(1.6), 95.1(3.1), and 87.7(6.5), respectively. Additionally, the proposed exercise and hypoxic stimulus was well-tolerated, since 93% of participants showed no or moderate acute mountain sickness symptoms; maintained nearly 80% of sets at target heart rate; and most frequently reporting session intensity as an RPE of "3" (moderate). The internal load calculation, analyzed through training impulse (TRIMP), calculated using HR [TRIMPHR = HR * training volume (min)] and RPE [TRIMPRPE = RPE * training volume (min)], showed no significant difference between groups. The current strategy effectively promoted the altitude simulation and monitoring variables, being well-tolerated and safely acute exposure, as the low Lake Louise scores and the stable HR, SpO2, and RPE values showed during the sessions.

Effect of hypoxic conditioning on functional fitness, balance and fear of falling in healthy older adults: a randomized controlled trial.

BACKGROUND: Hypoxic conditioning has been proposed as a new tool to mitigate the sarcopenia and enhance health-related function, but decrements in standing balance have been observed during hypoxia exposure. The aim of the study was to evaluate the effect of a hypoxic conditioning training on functional fitness, balance and fear of falling in healthy older adults. METHODS: A total of 54 healthy older adults (aged 65-75 years), who voluntarily participated in the study, were randomly divided into three groups: the control group (CON), the normoxia training group (NT) that performed strength training in normoxia, and the hypoxia training group (HT) that trained under moderate hypoxic conditions at a simulated altitude of 2500 m asl. The training programme that was performed during 24 weeks was similar in both experimental groups and consisted of a full-body workout with elastic bands and kettlebells (three sets × 12-15 reps). The Senior Fitness Test (SFT), the Single Leg Stance test (SLS) and the Short Falls Efficacy Scale-International (FES-I) were assessed before and after the intervention. RESULTS: Results showed that after training, either in normoxia or in hypoxia, the participants increased upper and lower body strength, and the aerobic endurance, and decreased the fear of falling. CONCLUSIONS: The moderate hypoxic conditioning seems to be a useful tool to increase the functional capacity in healthy older adults without observing a decline in balance. TRIAL REGISTRATION: ClinicalTrials.gov NCT04281264 . Registered February 9, 2019-Retrospectively registered.