Humans elicit a robust series of physiological responses to maintain adequate oxygen delivery during hypoxia, including a transient reduction in hemoglobin-oxygen (Hb-O
) affinity. However, high Hb-O
...affinity has been identified as a beneficial adaptation in several species that have been exposed to high altitude for generations. The observed differences in Hb-O
affinity between humans and species adapted to high altitude pose a central question: is higher or lower Hb-O
affinity in humans more advantageous when O
availability is limited? Humans with genetic mutations in hemoglobin structure resulting in high Hb-O
affinity have shown attenuated cardiorespiratory adjustments during hypoxia both at rest and during exercise, providing unique insight into this central question. Therefore, the purpose of this review is to examine the influence of high Hb-O
affinity during hypoxia through comparison of cardiovascular and respiratory adjustments elicited by humans with high Hb-O
affinity compared to those with normal Hb-O
affinity.
Maximal oxygen uptake (VO2 max) is the maximum amount of oxygen attainable by a person during exercise. VO2 max is used in different domains including sports and medical sciences and is usually ...measured during an incremental treadmill or cycle ergometer test. The drawback of directly measuring VO2 max using the maximal test is that it is expensive and requires a fixed and controlled protocol. During the last decade, various machine learning models have been developed for VO2 max prediction and numerous studies have attempted to predict VO2 max using data from submaximal and non-exercise tests. This article gives an overview of the machine learning models developed over the past five years (2016–2021) for the prediction of VO2 max. Multiple linear regression, support vector machine, artificial neural network and multilayer perceptron are some of the techniques that have been used to build predictive models using different combinations of predictor variables. Model performance is generally assessed using correlation coefficient (R-value), standard error of estimate (SEE) and root mean squared error (RMSE), computed between ground truth and predicted values. The findings of this review indicate that models using ANN typically outperform other machine learning techniques. Moreover, the predictor variables used to build the model have a large influence on the model's predictive performance.
Patients with schizophrenia suffer from physical health conditions, culminating in reduced physical functioning with enormous costs for patients and society. Although aerobic endurance and skeletal ...muscle strength, typically reduced in this population, relate to cognition and function, no study has explored their respective contributions to performance of functional skills and everyday tasks.
In a cross-sectional study, 48 outpatients (28/20 men/women; 35 ± 11(SD) years) with schizophrenia spectrum disorders (ICD-10; F20–25) were administered the UCSD Performance-based Skills Assessment-Brief (UPSA-B; functional skills), Specific Level of Functioning (SLOF; functional performance) and the Positive and Negative Syndrome (PANSS) scale. Peak oxygen uptake (V̇O2peak) was assessed along with leg press maximal muscle strength (1RM) and mechanical power.
UPSA-B performance was associated with V̇O2peak (r = 0.28,p < 0.05), accounting for 8 % (p < 0.05) of shared variance, but was unrelated to 1RM and mechanical power. The SLOF physical functioning domain was associated with V̇O2peak (r = 0.30,p < 0.05) and 1RM (r = 0.24,p < 0.05), while SLOF personal care (r = 0.27,p < 0.05) and activities (r = 0.30,p < 0.05) were related only to V̇O2peak. Hierarchical regression analyses revealed that while V̇O2peak and age combined to account for 20 % (p < 0.05) of the variance in physical functioning, the contribution of 1RM was eliminated after adjusting for age. V̇O2peak and negative symptoms combined predicted 24 % and 35 % of the variance in personal care and activities, respectively. UPSA-B scores did not add to the prediction of SLOF scores.
Although V̇O2peak and 1RM both relate to functional outcomes, the combination of V̇O2peak, age, and negative symptoms exert the greatest detrimental influence on functional performance beyond skills deficits.
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The purpose of this study was to analyze differences between endocrine markers in soccer players, based on playing positions, and correlations between endocrine markers (testosterone, cortisol, ...growth hormone, and insulin-like growth factor-1), with accumulated workload training and fitness parameters maximal oxygen uptake (VO
2max
), countermovement jump (CMJ), and isometric maximal strength (1-RM) of the knee for hamstring (ISH) and quadriceps (ISQ) muscles during early-, mid-, and end-seasons. Twenty-four elite soccer players under 17 participated in this study. The results showed that there was no difference between levels of the endocrine markers among the different positions of the players. Significant correlations were observed between endocrines parameters and fitness performance (ISQ, ISH, VO
2max
, and CMJ). Regression analysis showed that 1-RM and VO
2max
were the best predictors of endocrine markers. These findings demonstrated that the activity profiles of youth soccer players were not influenced by endocrine markers. Also, it may be assumed that endocrines levels can be used to better explain the physical capacities of this population. Finally, endocrines markers may help to predict changes in 1-RM and VO
2max
.
Improving peak oxygen uptake (V̇O2peak) and maximal strength are key objectives of rehabilitation for patients with unspecific musculoskeletal disorders (MSDs). Although high‐intensity training yield ...superior outcomes for these factors, patients with MSDs may not tolerate high‐intensity due to pain and fear. Therefore, we examined the effect and feasibility of incorporating aerobic high‐intensity intervals (HIITs) and maximal strength training (MST) in a standard clinical rehabilitation program for patients with unspecific MSDs. 73 patients (45 ± 10 years) with MSDs partaking in a standard, public, and 4‐week rehabilitation program were randomized to high‐intensity training (HG: 4 × 4 minutes intervals at ∼90% of maximal heart rate; HRmax, and 4 × 4 repetitions leg press at ∼90% of 1 repetition maximum; 1RM, with maximal intended velocity) or keep todays treatment of low‐to moderate‐intensity training (MG: various cycling, walking, and/or running activities at ∼70%–80% of HRmax and 3 × 8 − 10 repetitions leg press at ∼75% of 1RM without maximal intended velocity). HG improved V̇O2peak (12 ± 7%) and leg press 1RM (43 ± 34%) more than moderate‐intensity group (V̇O2peak; 5 ± 6%, 1RM; 19 ± 18%, both p < 0.001). We observed that no adverse events and no between‐group differences in dropout rate or self‐reported quality of life (both p > 0.05). There were positive correlations between improved V̇O2peak and improved physical (p = 0.024) and emotional (0.016) role functioning. We conclude that both high‐intensity interval training and MST are feasible and improve V̇O2peak and maximal strength more than standard low‐to moderate‐intensity treatment of patients with unspecific MSDs. Our findings suggest that high‐intensity training should be implemented as a part of standard clinical care of this patient population.
Highlights
Implementing aerobic high‐intensity interval training (HIIT) and maximal strength training (MST) induce a twofold effect on V̇O2peak and 1 repetition maximum compared to standard public short‐term rehabilitation in patients with unspecific musculoskeletal disorders (MSDs).
Concurrent HIIT and MST are as feasible as moderate exercise for patients with unspecific MSDs and should be implemented as a component in standard clinical care for these patients.
An improved V̇O2peak is associated with improved physical and emotional role functioning.
IntroductionMaximal oxygen uptake (V̇O2max) is a pivotal factor for aerobic endurance performance. Recently, aerobic high‐intensity interval training (HIIT) was documented to be superior to sprint ...interval training (SIT) in improving V̇O2max in well‐trained males. However, as mounting evidence suggests that physiological responses to training are sex‐dependent, examining the effects of HIIT versus SIT on V̇O2max, anaerobic capacity, and endurance performance in females is warranted.MethodsWe randomized 81 aerobically well‐trained females (22 ± 2 years, 51.8 ± 3.6 mL∙kg−1∙min−1 V̇O2max), training three times weekly for 8 weeks, to well‐established protocols: (1) HIIT 4 × 4 min at ~95% of maximal aerobic speed (MAS), with 3 min active recovery (2) SIT 8 × 20 s at ~150% of MAS, with 10 s passive recovery (3) SIT 10 × 30 s at ~175% of MAS, with 3.5 min active recovery.ResultsOnly HIIT 4 × 4 min increased V̇O2max (7.3 ± 3.1%), different from both SIT groups (all p < 0.001). Anaerobic capacity (maximal accumulated oxygen deficit) increased following SIT 8 × 20 s (6.5 ± 10.5%, p < 0.05), SIT 10 × 30 s (14.4 ± 13.7%, p < 0.05; different from HIIT 4 × 4 min, p < 0.05). SIT 10 × 30 s resulted in eight training‐induced injuries, different from no injuries following HIIT 4 × 4 min and SIT 8 × 20 s (p < 0.001). All groups improved long‐distance (3000‐meter) and sprint (300‐meter) running performance (all p < 0.001). SIT protocols improved sprint performance more than HIIT 4 × 4 min (p < 0.05). Compared to previous male results, no increase in V̇O2max following SIT 8 × 20 s (p < 0.01), and a higher injury rate for SIT 10 × 30 s (p < 0.001), were evident.ConclusionsIn aerobically well‐trained women, HIIT is superior to SIT in increasing V̇O2max while all‐out treadmill running SIT is potentially more harmful.
According to prior research, high-intensity endurance training (HIT) conducted more than twice a week significantly improves the maximum oxygen uptake (VO2max), a marker of cardiorespiratory fitness, ...compared to low or moderate-intensity training. This training modality not only benefits athletes but also aids individuals with metabolic syndrome and circulatory and respiratory conditions, enhancing their quality of life. Despite these potentials, exploratory studies of exercise regimens with shorter durations, lower frequencies, and fewer sets remain insufficient; thus minimalistic HIT protocols remain under-investigated. In this research, our objective was to investigate the impact of an even less frequent, once-weekly, maximum effort high-intensity training (HIT) on cardiorespiratory function and exercise performance across various age groups. We enrolled 11 healthy participants (4 males and 7 females;age 36.9±16.7 years;height 163.4±11.7cm;weight 58.4±10.6kg) to participate in exhaustive training sessions for 8 weeks. The intensity was set at 80%of their maximum load reached in an initial ramp test (80%WRmax) . Before and after the training, participants underwent ramp test and head-up tilt (orthostatic load) test to assess adaptations in cardiorespiratory function during maximum exercise and circulatory adjustment to postural changes. Exercise performance was evaluated by maximum exercise duration until exhaustion (Exhaustion Time) . Post-training results indicated significant improvements in VO2max (＋12%, p=0.02), ＋7.5% (p=0.026) WRmax＋12.7%, and Exhaustion Time. Furthermore, in the head-up tilt test, a significant increase in end-tidal CO2 partial pressure (PETCO2) (＋17.5%, p=0.04) was observed in the supine position, and PETCO2 increased by ＋11.9% (p=0.03) while tidal volume decreased by -19.9% (p=0.02) in the tilt position. Although no interaction was found in ANOVA, significant Primary effects of training and condition were observed for PETCO2. Our findings suggest that once-weekly HIT to maximum exertion enhances cardiorespiratory function and exercise performance. No changes in parameters maintaining blood pressure were observed during the head-up tilt test. These findings may be valuable for future development of efficient exercise training programs for wider age groups.
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