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The study aimed to calculate training intensity and load using muscle oxygen saturation (SmO2) during two differentiated physical tasks. 29 university athletes participated in a 40-m Maximal Shuttle Run Test (MST, 10 × 40-m with 30 s recovery between sprints) and a 3000-m time trial run. Distance and time were used to calculate external load (EL). Internal load indicators were calculated based on percentage of maximum heart rate (%HRMAX) and SmO2 variables: muscle oxygen extraction (∇%SmO2) and the cardio-muscle oxygen index (CMOI) was also provided by relating ∇%SmO2 ÷ %HRMAX, and the training load were calculated as the product of speed (m/min × IL) and the efficiency index [Effindex (m/min ÷ IL)]. A student t test was applied based on Bayesian factor analysis. As expected, EL differed in the 40-m MST (331 ± 22.8) vs. 3000-m trials (222 ± 56.8) [BF10 = 6.25e+6; p = <0.001]. Likewise, IL showed higher values in 40-m MST (39.20 ± 15.44) vs. 3000-m (30.51 ± 8.67) in CMOI: [BF10 = 1.70; p = 0.039]. Training load was greater in 40-m MST (85.77 ± 27.40) vs. 3000-m (15.55 ± 6.77) [(m/min × ∇%SmO2): BF10 = 12.5; p = 0.003] and 40-m MST (129.27 ± 49.44) vs. 3000-m (70.63 ± 32.98) [(m/min × CMOI): BF10 = 169.6; p = <0.001]. Also, the Effindex was higher in 40-m MST (10.19 ± 4.17) vs. 3000-m (6.06 ± 2.21) [(m/min × ∇%SmO2): BF10 = 137.03; p = <0.001] and 40-m MST (9.69 ± 4.11) vs. 3000-m (7.55 ± 1.87) [(m/min × CMOI): BF10 = 1.86; p = 0.035]. This study demonstrates calculations of training intensity and load based on SmO2 as an internal load indicator along with speed as an external load indicator during two differentiated exercises. [ABSTRACT FROM AUTHOR]

Background: Aging is associated with a health impairment and an increase of the vulnerability of the older people. Strength training under intermittent hypoxic conditions has been shown to have therapeutic effects on individual’s health. Aims: The aim of this study was to investigate the effects of a combined intermittent hypoxia (IH) and whole-body vibration (WBV) training program on health-related outcomes in older people. Methods: A total of 60 adults (over the age of 65) voluntarily participated in an intervention that lasted 20 weeks (three 30-min sessions per week). The participants were divided into four experimental groups subjected to different environmental conditions (IH vs normoxia) and exercise (non-exercise vs WBV). Functional fitness, body composition, metabolic parameters, inflammatory biomarkers, and bone turnover were evaluated before and after the intervention. A multifactorial ANOVA with repeated measures was performed to explore differences within and between groups. Results: The results showed that IH and WBV had a positive synergistic effect on inflammatory parameters (CRP and IL-10), bone formation biomarker (PINP), and body composition (muscle and bone mass). Conclusion: In conclusion, a combined IH and WVB training could be a useful tool to prevent the deterioration of health-related outcomes associated with aging. Clinical trial registration NCT04281264. . [ABSTRACT FROM AUTHOR]

Purpose: It has been hypothesized that sports injury risk is explained by muscle metabolism. The objective was to evaluate the muscle oxygen saturation slopes (ΔSmO2 slopes) and muscle oxygenation asymmetry (MO2Asy) at rest and to study their associations with injuries during the pre-season. Methods: A total of 16 male and 10 female footballers participated in this study. Injuries were diagnosed and classified by level of severity during the pre-season. The workload was also evaluated using the rate of perceived exertion × training time, from which the accumulated loads. The SmO2 was measured at rest in the gastrocnemius muscle using the arterial occlusion method in the dominant and non-dominant legs. The repeated measures ANOVA, relative risk, and binary logistic regression were applied to assess the probability of injury with SmO2 and workload. Results: Higher MO2Asy and ΔSmO2 Slope 2 were found among footballer who suffered high-severity injuries and those who presented no injuries. In addition, an MO2Asy greater than 15% and an increase in accumulated load were variables that explained a greater probability of injury. Conclusion: This study presents the new concept of muscle oxygenation asymmetry in sports science and its possible application in injury prevention through the measurement of SmO2 at rest. [ABSTRACT FROM AUTHOR]

Purpose: Near-infrared spectroscopy (NIRS) sensors measure muscle oxygen saturation (SmO2) as a performance factor in endurance athletes. The objective of this study is to delimit metabolic thresholds relative to maximal metabolic steady state (MMSS) using SmO2 in cyclists. Methods: Forty-eight cyclists performed a graded incremental test (GTX) (100 W-warm-up followed by 30 W min) until exhaustion. SmO2 was measured with a portable NIRS placed on the vastus lateralis. Subjects were classified by VO2max levels with a scale from 2 to 5: L2 = 45–54.9, L3 = 55–64.9, L4 = 65–71, L5 = > 71, which represent recreationally trained, trained, well-trained, and professional, respectively. Then, metabolic thresholds were determined: Fatmax zone, functional threshold power (FTP), respiratory compensation point (RCP), and maximal aerobic power (MAP). In addition, power output%, heart rate%, VO2%, carbohydrate and fat consumption to cutoff SmO2 point relative to MMSS were obtained. Results: A greater SmO2 decrease was found in cyclists with > 55 VO2max (L3, L4 and L5) vs. cyclists (L2) in the MMSS. Likewise, after passing FTP and RCP, performance is dependent on better muscle oxygen extraction. Furthermore, the MMSS was defined at 27% SmO2, where a non-steady state begins during exercise in trained cyclists. Conclusion: A new indicator has been provided for trained cyclists, < 27% SmO2 as a cut-off to define the MMSS Zone. This is the intensity for which the athlete can sustain 1 h of exercise under quasi-steady state conditions without fatiguing. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

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 [FIO 2 ]: 0.17) or the same training in normoxia (control group, n = 41; FIO 2 : 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.