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Cardiorespiratory fitness (CRF) is a crucial indicator for assessing an individual's maximal oxygen uptake capacity. Although numerous studies have investigated the effects of exercise on CRF, comparisons between high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) in individuals aged 40 and above remain limited and fragmented. This research employs a Systematic Literature Review (SLR) and meta-analysis to evaluate the effectiveness of HIIT and MICT in improving VO2peak in individuals aged 40 and above. Data were collected from Scopus and WoS databases using the PRISMA method. Articles that met the inclusion criteria were analyzed using RevMan 5.4 and JASP 0.18.3. The analysis revealed that HIIT has a greater advantage in enhancing VO2peak compared to MICT in individuals aged 40 and above. Overall, HIIT increased VO2peak with a z-value of 5.59 (p-value < 0.00001) and a 95% confidence interval of 0.35 [0.23, 0.48]. Conversely, MICT showed a z-value of 1.84 (p-value = 0.07) and a 95% confidence interval of 0.11 [-0.01, 0.23]. Inter-study heterogeneity was low to moderate, with an I² value of 25% and τ² of 0.03 for HIIT, and an I² value of 0% for MICT. HIIT tends to be more effective than MICT in improving cardiorespiratory fitness in individuals aged 40 and above. However, the difference between the two methods is not statistically significant. Further research with more homogeneous designs and longer intervention durations is needed to confirm these findings and understand the underlying mechanisms of the differences in effectiveness between HIIT and MICT. Keywords: HIIT, MICT, VO2peak, CRF, exercise

ObjectiveThis study aims to construct quantile reference values for peak oxygen uptake (V̇O2peak) measured by cycle ergometry-based incremental cardiopulmonary exercise tests.DesignCross-sectional study using quantile regressions to fit sex-specific and age-specific quantile curves. Exercise tests were conducted using cycle ergometry. Maximal effort in the exercise tests was assumed when respiratory exchange ratio  ≥1.1 or lactate ≥8 mmol/L or maximal heart rate ≥90% of the age-predicted maximal heart rate. This was assessed retrospectively for a random subsample with an a priori calculated sample size of n=252 participants.SettingA network of private outpatient clinics in three German cities recorded the results of cycle ergometry-based cardiopulmonary exercise tests to a central database (Prevention First Registry) from 2001 to 2015.Participants10 090 participants (6462 men, 3628 women) from more than 100 local companies volunteered in workplace health promotion programmes. Participants were aged 21 to 83 years, were free of acute complaints and had primarily sedentary working environments.Main outcome measurePeak oxygen uptake was measured as absolute V̇O2peak in litres of oxygen per minute and relative V̇O2peak in millilitres of oxygen per kilogram of body mass per minute.ResultsThe mean age for both men and women was 46 years. Median relative V̇O2peak was 36 and 30 mL/kg/min at 40 to 49 years, as well as 32 and 26 mL/kg/min at 50 to 59 years for men and women, respectively. An estimated proportion of 97% of the participants performed the exercise test until exertion.ConclusionsReference values and nomograms for V̇O2peak were derived from a large sample of preventive healthcare examinations of healthy white-collar workers. The presented results can be applied to participants of exercise tests using cycle ergometry who are part of a population that is comparable to this study.

The maximal lactate steady state (MLSS) represents the highest exercise intensity at which an elevated blood lactate concentration ([Lac]b) is stabilized above resting values. MLSS quantifies the boundary between the heavy-to-very-heavy intensity domains but its determination is not widely performed due to the number of trials required. This study aimed to: (i) develop a mathematical equation capable of predicting MLSS using variables measured during a single ramp-incremental cycling test and (ii) test the accuracy of the optimized mathematical equation. The predictive MLSS equation was determined by stepwise backward regression analysis of twelve independent variables measured in sixty individuals who had previously performed ramp-incremental exercise and in whom MLSS was known (MLSSobs). Next, twenty-nine different individuals were prospectively recruited to test the accuracy of the equation. These participants performed ramp-incremental exercise to exhaustion and two-to-three 30-min constant-power output cycling bouts with [Lac]b sampled at regular intervals for determination of MLSSobs. Predicted MLSS (MLSSpred) and MLSSobs in both phases of the study were compared by paired t-test, major-axis regression and Bland–Altman analysis. The predictor variables of MLSS were: respiratory compensation point (Wkg−1), peak oxygen uptake (V˙O2peak) (mlkg−1min−1) and body mass (kg). MLSSpred was highly correlated with MLSSobs (r=0.93; p<0.01). When this equation was tested on the independent group, MLSSpred was not different from MLSSobs (234±43 vs. 234±44W; SEE 4.8W; r=0.99; p<0.01). These data support the validity of the predictive MLSS equation. We advocate its use as a time-efficient alternative to traditional MLSS testing in cycling.

Background Peak oxygen uptake (VO 2peak ) is the gold standard for assessing cardiorespiratory fitness, but many patients with stroke cannot complete maximal cardiopulmonary exercise tests (CPET) due to motor impairments. This study aimed to explore indicators correlated with VO 2peak and to investigate preliminary screening approaches for assessing cardiorespiratory fitness in patients with subacute stroke. Methods This was a cross-sectional study. The study was registered on 2 July 2020. Participants were male patients with ischaemic and haemorrhagic strokes, who were hospitalised in the Rehabilitation Department of Shenzhen Second People’s Hospital between August 2020 and March 2023. Handgrip strength (HS) on the affected side and unaffected side was measured using a hydraulic hand dynamometer. VO 2peak was measured using a cardiopulmonary exercise test system. Univariate and ​theory-driven forced-entry multiple linear regression analyses were used to evaluate the association between participant characteristics and VO 2peak . Results A total of 116 male patients with subacute stroke (mean age: 52 years) were included in the analysis. Multivariate regression analysis revealed that the weight-adjusted HS on the unaffected side was independently associated with VO 2peak . A combination of age, body surface area, Barthel Index, key clinical variables (disease duration and hypertension), and submaximal CPET indicators (anaerobic threshold, oxygen uptake efficiency slope, minute ventilation to carbon dioxide production slope) explained 73.6% of the variance in VO 2peak . The addition of weight-adjusted HS on the unaffected side increased the explained variance to 74.8%. Conclusions Submaximal exercise testing may offer an alternative approach for evaluating cardiorespiratory fitness in patients with stroke who are unable to perform maximal testing. HS assessment could serve as a preliminary screening tool for estimating aerobic capacity in patients with stroke, particularly in resource-limited settings, or may complement CPET parameters in tracking rehabilitation outcomes. Trial registration The study protocol was registered in the Chinese Clinical Trial Registry (ChiCTR2000035308, Registration date: August 7, 2020, https://www.chictr.org.cn/bin/project/edit?pid=57565 ).

Beta-alanine (βA) is a non-essential amino acid purportedly used to enhance aerobic exercise performance. While previous research indicates the benefits of βA on time to exhaustion (TTE) and aerobic capacity (VO ) in adults, evidence is lacking in adolescent athletes. Thus, the purpose of this study was to determine the effects of 4 weeks of βA supplementation on aerobic performance in adolescent runners. Twenty-seven middle- and long-distance runners (aged 17.36 ± 2.17 years) were randomly divided into a βA or placebo (PL) group (maltodextrin). Subjects performed maximal graded exercise tests (GXT) and submaximal trials (SMT; 80% of VO for 1500 m) on a treadmill before and after 14 and 28 days of supplementation or PL. Respiratory (V ) metabolic (VO , RER, lactate [La]), and cardiovascular (HR) variables were measured during the GXT and SMT, along with the first (VT1) and second ventilatory threshold (VT2) and TTE monitored during the GXT only. Within- and between-group differences were assessed using a repeated-measures mixed-model analysis of variance. Findings indicated that despite a trivial increase in VO over 4 weeks, the βA group increased TTE by 6.5% compared to 1.4% in the PL group (  = 0.46). Additionally, small effects in HR , V , [La], and TTE were observed between groups favoring βA. Regarding the SMT, both average HR and RER decreased by 4% in the βA group, with no changes for the PL. Despite no evidence to suggest increases in VO , practitioners should note that improvements in TTE may be observed after 28 days of βA supplementation in adolescent runners.

Cardiorespiratory fitness (CRF) is a crucial indicator for assessing an individual's maximal oxygen uptake capacity. Although numerous studies have investigated the effects of exercise on CRF, comparisons between high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) in individuals aged 40 and above remain limited and fragmented. This research employs a Systematic Literature Review (SLR) and meta-analysis to evaluate the effectiveness of HIIT and MICT in improving VO2peak in individuals aged 40 and above. Data were collected from Scopus and WoS databases using the PRISMA method. Articles that met the inclusion criteria were analyzed using RevMan 5.4 and JASP 0.18.3. The analysis revealed that HIIT has a greater advantage in enhancing VO2peak compared to MICT in individuals aged 40 and above. Overall, HIIT increased VO2peak with a z-value of 5.59 (p-value < 0.00001) and a 95% confidence interval of 0.35 [0.23, 0.48]. Conversely, MICT showed a z-value of 1.84 (p-value = 0.07) and a 95% confidence interval of 0.11 [-0.01, 0.23]. Inter-study heterogeneity was low to moderate, with an I² value of 25% and τ² of 0.03 for HIIT, and an I² value of 0% for MICT. HIIT tends to be more effective than MICT in improving cardiorespiratory fitness in individuals aged 40 and above. However, the difference between the two methods is not statistically significant. Further research with more homogeneous designs and longer intervention durations is needed to confirm these findings and understand the underlying mechanisms of the differences in effectiveness between HIIT and MICT. La aptitud cardiorrespiratoria (ACR) es un indicador crucial para evaluar la capacidad máxima de consumo de oxígeno de un individuo. Aunque numerosos estudios han investigado los efectos del ejercicio en la ACR, las comparaciones entre el entrenamiento interválico de alta intensidad (HIIT) y el entrenamiento continuo de intensidad moderada (MICT) en individuos de 40 años o más siguen siendo limitadas y fragmentadas. Esta investigación emplea una revisión sistemática de la literatura (SLR) y un meta-análisis para evaluar la eficacia del HIIT y el MICT en la mejora del VO2máx en individuos de 40 años o más. Los datos se recopilaron de las bases de datos Scopus y WoS utilizando el método PRISMA. Los artículos que cumplieron con los criterios de inclusión fueron analizados utilizando RevMan 5.4 y JASP 0.18.3. El análisis reveló que el HIIT tiene una mayor ventaja en la mejora del VO2peak en comparación con el MICT en individuos de 40 años o más. En general, el HIIT aumentó el VO2peak con un valor z de 5.59 (valor p < 0.00001) y un intervalo de confianza del 95% de 0.35 [0.23, 0.48]. Por el contrario, el MICT mostró un valor z de 1.84 (valor p = 0.07) y un intervalo de confianza del 95% de 0.11 [-0.01, 0.23]. La heterogeneidad entre estudios fue de baja a moderada, con un valor de I² del 25% y τ² de 0.03 para HIIT, y un valor de I² del 0% para MICT. El HIIT tiende a ser más efectivo que el MICT en la mejora de la aptitud cardiorrespiratoria en individuos de 40 años o más. Sin embargo, la diferencia entre los dos métodos no es estadísticamente significativa. Se necesita más investigación con diseños más homogéneos y duraciones de intervención más largas para confirmar estos hallazgos y comprender los mecanismos subyacentes de las diferencias en la eficacia entre HIIT y MICT.

Although aerobic exercise is the primary modality recommended for the treatment of hypertension, it remains unclear whether high-intensity all-out sprint interval training (SIT) can result in greater reductions of blood pressure (BP) and cardiorespiratory health. This systematic review aims to compare the impact of SIT Moderate-intensity continuous training (MICT) on improvements in resting systolic blood pressure (SBP), diastolic blood pressure (DBP) and maximal oxygen uptake (VO max) among adults. We conducted a systematic search of three online databases (PubMed, Embase, and Web of Science) from January 2000 to July 2023 to identify randomized controlled trials that compared the chronic effects of SIT MICT on BP in participants with high or normal blood pressure. We extracted information on participant characteristics, exercise protocols, BP outcomes, and intervention settings. Furthermore, the changes in VO max between the two groups were analyzed using a meta-analysis. The pooled results were presented as weighted means with 95% confidence intervals (CI). Out of the 1,874 studies initially were found, eight were included in this review, totaling 169 participants. A significant decrease in SBP (MD = -2.82 mmHg, 95% CI [-4.53 to -1.10],  = 0.08, =45%) was observed in the SIT group compared to before the training, but no significant decrease in DBP (MD = -0.75 mmHg, 95% CI [-1.92 to 0.42],  = 0.16, = 33%) was observed. In contrast, both SBP (MD = -3.00 mmHg, 95% CI [-5.31 to -0.69],  = 0.68, = 0%) and DBP (MD = -2.11 mmHg, 95% CI [-3.63 to -0.60],  = 0.72, = 0%) significantly decreased in the MICT group with low heterogeneity. No significant difference was found in resting SBP and DBP between SIT and MICT after the intervention. Both SIT and MICT significantly increased VO peak, with SIT resulting in a mean difference (MD) of 1.75 mL/kg/min (95% CI [0.39-3.10],  = 0.02, = 61%), and MICT resulting in a mean difference of 3.10 mL/kg/min (95% CI [1.03-5.18],  = 0.007, = 69%). MICT was more effective in improving VO peak (MD = -1.36 mL/kg/min, 95% CI [-2.31 to 0.40],  = 0.56, = 0%). Subgroup analysis of duration and single sprint time showed that SIT was more effective in reducing SBP when the duration was ≥8 weeks or when the sprint time was <30 s. Our meta-analysis showed that SIT is an effective intervention in reducing BP and improving cardiorespiratory fitness among adults. Consequently, SIT can be used in combination with traditional MICT to increase the variety, utility, and time efficiency of exercise prescriptions for different populations.

Background: The aim of this study was to investigate the effects of a monitored exercise program on aerobic fitness in children with cystic fibrosis (CF). Methods: Six children (2f/4m) with ages ranging from 6 to 14 years (11.3 ± 3.3 years.) and a mean ppFEV1 102.5 ± 13.5% pred. participated in the partially monitored 12-month exercise program. VO2peak and Wpeak were used as parameters of aerobic fitness. Incremental Cardio-Pulmonary Exercise Tests (CPETs) were performed before the program began (T1), after 6 months (T3) of monitoring, and after a further 6 months (T4) without monitoring. Habitual physical activity (HPA) was assessed with accelerometry. Results: The values of VO2peak and Wpeak improved slightly from T1 to T3 (p > 0.05), without a further increase after monitoring was stopped (T4). However, the VO2peak and Wpeak values were higher after monitoring was stopped compared to at T1. The exercise program with and without monitoring (p > 0.05) had no or only a slight effect on the FEV1 values, steps/day, and the intensity of HPA. Conclusions: Monitoring seems to facilitate the achievement of beneficial effects on physical fitness in CF children. For that reason, continuous individual exercise monitoring programs that involve close contact with an exercise therapist should be provided to maintain long-term motivation and participation in physical activities and sport activities during leisure time.

Accurate assessment of cardiorespiratory fitness (CRF) in adolescents is critical. However, normalizing oxygen consumption (VO2) to body mass (BM) may underestimate CRF in overweight (OW) youth by including metabolically inactive fat mass. This study examined differences in VO2 normalized by BM and fat-free mass (FFM) between normal weight (NW) and OW adolescents. Thirty-eight participants (19 NW, 19 OW; 12–17 years) underwent anthropometric, body composition, and cardiorespiratory fitness assessments. VO2 at the aerobic threshold (VO2AerT), anaerobic threshold (VO2AnT), and peak exercise (VO2peak) were measured and expressed in absolute terms and relative to BM and FFM. Group differences in the main outcomes were analyzed using a one-way ANOVA, and Pearson correlation was used to examine associations between VO2, BM and FFM. When normalized by BM, NW adolescents showed significantly higher VO2AerT (18.7 ± 3.6 vs. 14.5 ± 2.3), VO2AnT (28.8 ± 6.3 vs. 23.6 ± 4.7), and VO2peak (37.7 ± 6.7 vs. 29.1 ± 7.0) compared to OW peers (p < 0.05). No significant differences were found when VO2 values were normalized by FFM. A group difference was observed in the VO2peak vs. BM slope (p = 0.03) but not in the VO2peak vs. FFM slope. FFM normalization provides a more accurate assessment of CRF by accounting for differences in body composition, underscoring the importance of evaluating the aerobic capacity of metabolically active tissue rather than total body weight in youth populations.

Background Inorganic nitrate (NO 3 − ) supplementation is purported to benefit short-term exercise performance, but it is unclear whether NO 3 − improves longer-term exercise training responses (such as improvements in VO 2peak or time to exhaustion (TTE)) versus exercise training alone. The purpose of this systematic review and meta-analysis was to determine the effects of NO 3 − supplementation combined with exercise training on VO 2peak and TTE, and to identify potential factors that may impact outcomes. Methods Electronic databases (PubMed, Medscape, and Web of Science) were searched for articles published through June 2022 with article inclusion determined a priori as: (1) randomized placebo-controlled trials, (2) exercise training lasted at least three weeks, (3) treatment groups received identical exercise training, (4) treatment groups had matched VO 2peak at baseline. Study quality was assessed using the Cochrane Risk-of-Bias 2 tool. Standardized mean difference (SMD) with 95% confidence intervals (CI) were calculated using restricted maximum likelihood estimation between pre- and post-training differences in outcomes. Moderator subgroup and meta-regression analyses were completed to determine whether the overall effect was influenced by age, sex, NO 3 − dosage, baseline VO 2peak , health status, NO 3 − administration route, and training conditions. Results Nine studies consisting of eleven trials were included: n = 228 (72 females); age = 37.7 ± 21 years; VO 2peak : 40 ± 18 ml/kg/min. NO 3 − supplementation did not enhance exercise training with respect to VO 2peak (SMD: 0.18; 95% CI: -0.09, 0.44; p  = 0.19) or TTE (SMD: 0.08; 95% CI: − 0.21, 0.37; p  = 0.58). No significant moderators were revealed on either outcome. Subset analysis on healthy participants who consumed beetroot juice (BRJ) revealed stronger trends for NO 3 − improving VO 2peak ( p  = 0.08) compared with TTE ( p  = 0.19), with no significant moderators. Sunset funnel plot revealed low statistical power in all trials. Conclusions NO 3 − supplementation combined with exercise training may not enhance exercise outcomes such as VO 2peak or TTE. A trend for greater improvement in VO 2peak in healthy participants supplemented with BRJ may exist ( p  = 0.08). Overall, future studies in this area need increased sample sizes, more unified methodologies, longer training interventions, and examination of sex as a biological variable to strengthen conclusions. Key Points Despite the increased use and study of NO 3 − supplementation, most of these data have shown benefits during acute supplementation on exercise rather than a benefit to chronic training outcomes. This systematic review and meta-analysis revealed non-significant improvements in VO 2peak or time to exhaustion after exercise training with NO 3 - supplementation compared to exercise alone. A trend for improvement was found for improvements in healthy participants taking beetroot juice supplementation. These results suggest that NO 3 - may not have an impact on improving longer term training outcomes, but studies in this area suffer from low sample sizes and inconsistent study designs.