PubMed HealthSearch

SEARCH · PubMed Health

Results for “Cardiorespiratory fitness”

Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 19 recordsLinked to original sources

Impact of Annual School Fitness Reports on Students' Cardiorespiratory Fitness: A Cluster-Randomized Controlled Trial of Parental Reporting.

BACKGROUND: School-based physical fitness testing is an important population health monitoring tool and has the potential to improve student fitness performance. However, few studies exist on the impact of reporting student fitness to parents. METHODS: Using data from the Fit Study (2014-2017) from 12 California public schools, we used mixed-effects models to compare changes in cardiorespiratory fitness (estimated peak oxygen consumption, calculated from the 1-mile run) and strength (curl-ups and push-ups) over 1 and 2 years between students randomized to having their parents receive an annual fitness report (intervention, n = 1638 students) and control (n = 2070) in grades 5 to 8 (ages 10-15 y). The student sample was 47.9% female, 55.9% Hispanic, and 24.1% Asian. RESULTS: After 1 year, intervention students did not demonstrate differential change compared with control students in estimated peak oxygen consumption (between-group change: -0.03 mL/kg/min; 95% CI, -.367 to 0.302), curl-ups (between-group change: 1.2 curl-ups; 95% CI, -0.306 to 2.660), or push-ups (between-group change: 0.1 push-ups; 95% CI, -0.672 to 0.787). Similarly, no differences were seen after 2 years. CONCLUSION: Sending a 2-page, once-a-year school-based fitness report home to parents-in the absence of environmental changes and/or behavioral coaching and support-does not impact student fitness performance after either 1 or 2 years of reporting.

fitness reporting

Epigenetic age acceleration is not strongly associated with cardiorespiratory fitness in heart failure: a pilot study.

BACKGROUND: In heart failure (HF), standard measures such as left ventricular ejection fraction and cardiopulmonary exercise testing incompletely capture interindividual differences in disease status or prognosis. DNA methylation (DNAm) epigenetic clocks, which estimate biological age and epigenetic age acceleration (EAA), may provide complementary insight into cardiorespiratory fitness and systemic aging in HF. RESEARCH DESIGN AND METHODS: We analyzed peripheral blood DNAm from fourteen patients enrolled in REDHART2, a clinical trial of interleukin-1 blockade following hospitalization for acute systolic HF. Genome-wide DNAm was assayed using Illumina EPIC arrays and several clocks were applied to these data. Associations between biological age or EAA and cardiorespiratory fitness measures, inflammatory markers, and clinical parameters were evaluated. RESULTS: All epigenetic clocks demonstrated moderate to strong correlations with chronological age. Biological age was consistently associated with measures of cardiorespiratory fitness, particularly oxygen consumption normalized to fat free mass (VO2_FFM). However, chronological age showed similar associations, and biological age did not significantly improve prediction of VO2 parameters beyond chronological age alone. EAA was not significantly associated with cardiorespiratory fitness for any clock. CONCLUSIONS: In this pilot study, neither biological age nor EAA provided significant predictive value beyond chronological age for cardiorespiratory fitness in patients with HF. CLINICAL TRIAL REGISTRATION NUMBER: NCT03797001.

DNA methylation

Validation of a bench stepping test for cardiorespiratory fitness classification of emergency service personnel.

Field tests are used in many occupations to screen and classify personnel for cardiorespiratory fitness. Presumably these tests yield predictive results which correlate well with maximal oxygen uptake (VO2 max), the most widely-accepted criterion of cardiorespiratory fitness. The purpose of this study was to validate one of the most popular field tests, the modified Kasch Pulse Recovery Step Test (KPRST), used by several emergency service agencies in Southern California. One hundred fourteen male state traffic officers from the California Highway Patrol, ranging in age from 24 to 56 years, performed treadmill VO2 max tests to volitional fatigue and the modified KPRST. Heart rates taken during the first and last 10 seconds of the one-minute recovery period for the modified KPRST compared against treadmill VO2 max values yielded correlations of --0.25 and --0.27, respectively, indicating that the modified KPRST is a poor predictor of cardiorespiratory fitness for the population studied. These results suggest that agencies should carefully validate any predictive measure of cardiorespiratory health and performance before adopting that measure for screening purposes and cardiorespiratory classification.

Adult

Optimising Exercise Prescription: A Meta-Analysis Examining the Dose Response of Exercise Duration on Cardiorespiratory Fitness Following HIIT and MICT.

BACKGROUND: High-intensity interval training (HIIT) is often promoted as a time-efficient alternative to moderate-intensity continuous training (MICT) for improving cardiorespiratory fitness, yet the duration of HIIT sessions varies considerably across studies. OBJECTIVE: We aimed to characterise the dose-response relationship between exercise session duration and the improvement in cardiorespiratory fitness for HIIT and MICT. METHODS: A dose-response meta-analysis of randomised controlled trials comparing exercise duration in HIIT and MICT, following Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines and registered in PROSPERO (CRD42022335590). Effect sizes were calculated using a random-effects meta-analysis. The primary outcome was maximal oxygen uptake (VO2max). Secondary outcomes included blood pressure, lipid profiles, glucose metabolism markers and body composition measures. A one-stage random-effects dose-response meta-analysis was performed to examine the relationship between exercise duration and adaptations. We searched PubMed and Google Scholar; eligibility criteria for selecting studies were randomised controlled trials in humans, published in English and exercise interventions lasting at least 4&#xa0;weeks. RESULTS: We identified 69 randomised controlled trials (2387 participants). High-intensity interval training elicited greater improvements in VO2max than MICT (d = 0.38, 95% confidence interval 0.27-0.49, p < 0.001). High-intensity interval training demonstrated a non-linear dose-response relationship between exercise session duration and VO2max, with 80% of maximal effect (changes in VO2max = 3.45&#xa0;mL/kg/min) achieved with only ~11&#xa0;min/session (95% confidence interval 9.5-40.2). Moderate-intensity interval training showed a linear dose-response relationship between exercise session duration and VO2max, requiring ~52&#xa0;min/session to achieve 80% of the&#xa0;maximal observed&#xa0;effect (95% confidence interval 30.4-55.8). The dose-response relationship was consistent across populations. High-intensity interval training and MICT had comparable effects in improving cardiometabolic risk factors. CONCLUSIONS: High-intensity interval training demonstrated a non-linear dose response, with 80% of maximal effect on VO2max in ~11&#xa0;min/session, whilst MICT required four to five times longer to reach similar responses. The different types of training had comparable effects on cardiometabolic risk factors.

Journal Article

Field testing of cardiorespiratory fitness in primary school children.

The purpose of the investigation was to explore the validity of using timed distance runs as predictors of cardiorespiratory fitness in first, second and third grade children. Maximal oxygen uptake (Vo2 max), determined via the open-circut method during treadmill running, and performance on runs of 800, 1200 and 1600 meters were compared for 83 children. Males were found to exceed females on Vo2 max and possessed significantly faster times on all the distances run. The 1600-meter run proved to be the best predictor of Vo2 max (ml/kg) in both sexes. Test-retest reliability of the 1600-meter run was checked with 120 students and found to range from +.824 for first grade females to + .918 for third grade males. Normative values for first, second, and third grade students were calculated from data collected on 1440 elementary students. All subjects studied had previously received instruction and practice on the phenomenon of paced distance running.

Child

Relationships among cardiorespiratory fitness, regular physical activity, and plasma lipids in young adults.

Relationships between physical activity and plasma lipids and between cardiorespiratory (CR) fitness and plasma lipids were investigated in 152 young adults. There were no significant correlations in either females or males between the physical activity indicators and any of the plasma lipids investigated. CR fitness, as indicated by treadmill test duration, showed a small but statistically significant sexes, an association that may well underestimate the true relationship because of the limitations of the study. Plasma triglycerides were negatively correlated with CR fitness in the males. It was suggested that the two fitness components, aerobic capacity and percent fat, may be related to certain plasma lipids differently in males than in females.

Adolescent

Relationship between cardiorespiratory fitness and physiological responses to films.

Subject's physiological responses and rated reactions to a medical film and an erotic film were assessed. Later cardiovascular fitness levels were determined by subject's physiological responses to an exercise task. The greater the increase in the subject's systolic blood pressure after exercise and the slower the recovery, the lower the fitness level. A median split on the fitness scores of males and females separately was used to determine levels of relatively low and high fitness. Subjects in low fitness had significantly greater sympathetic-arousal responses to the two films as measured in systolic blood-pressure increases and skin-temperature decreases. Subjects in the two fitness levels did not differ in ratings of their own physiological or emotional responses to the films. Reported interoception of the magnitude of physiological responses was inaccurate, especially for subjects in low fitness.

Adolescent

Effects of an internet-based combined exercise and cognitive-behavioral therapy intervention on endocannabinoid system biomarkers and physical fitness in adults with mild-to-moderate depression: a SONRIE randomized controlled trial.

BACKGROUND: This SONRIE randomized controlled trial (NCT05849792) examined the effects of a 12-week combined physical exercise and internet-based cognitive-behavioral therapy (iCBT) intervention on endocannabinoid system (ES) biomarkers and physical fitness in adults with mild-to-moderate depression. METHODS: Eighty adults were randomly assigned 1:1 to an intervention (IG) or control (CG) group. Outcomes included nine ES biomarkers (2-arachidonoylglycerol, 2-AG; anandamide, AEA; seven analogues) and physical fitness, including cardiorespiratory fitness (CRF; 6-minute walking test) and muscular strength. Measurements were taken at baseline, post-intervention and 8-week follow-up. Primary analysis performed 2&#x2009;&#xd7;&#x2009;3 repeated-measures ANOVA on completers; mixed-effects intention-to-treat model as sensitivity analysis. RESULTS: No significant time &#xd7; group interaction was detected for any ES biomarker, including 2-AG (F(2,88)&#x2009;=&#x2009;0.17, p&#x2009;=&#x2009;0.844) and AEA (F(2,88)&#x2009;=&#x2009;1.20, p&#x2009;=&#x2009;0.306); both groups showed comparable within-group decreases in 2-AG, 2-LG and 2-OG. The intervention significantly improved CRF [between-group difference&#x2009;+&#x2009;81.6&#xa0;m at 12 weeks (F(2,78)&#x2009;=&#x2009;7.88, p&#x2009;=&#x2009;0.001)], exceeding the established minimal clinically important difference. None of the exploratory muscular fitness outcomes reached statistical significance; the arm curl test showed a borderline non-significant interaction (F(2,78)&#x2009;=&#x2009;2.83, p&#x2009;=&#x2009;0.065). CONCLUSION: A 12-week internet-based combined exercise and iCBT intervention significantly improved CRF in adults with mild-to-moderate depression. We did not find evidence of an intervention-specific effect on plasma ES biomarkers. These findings support the inclusion of internet-delivered exercise and psychological interventions in comprehensive treatment strategies for depression. TRIAL REGISTRATION: ClinicalTrials.gov NCT05849792 (registered 6 May 2023).

Humans

Tumor Signatures of Physical Fitness: Insights from a Preclinical Model.

PURPOSE: Cardiorespiratory fitness (CRF) and muscle strength are associated with cancer risk/mortality in adults. However, there is yet no evidence for pediatric tumors. This study investigated the association of CRF and muscle strength with several tumor-related phenotypes in an aggressive childhood malignancy, high-risk neuroblastoma. METHODS: Twelve mice-bearing orthotopic high-risk neuroblastomas were studied. CRF and muscle strength were assessed using treadmill and grip strength testing, respectively. The following tumor-related outcomes were studied: survival, clinical severity, tumor weight/volume, metastasis, and intratumor immune infiltrates. In addition, tumor samples underwent quantitative proteomic analysis via liquid chromatography-tandem mass spectrometry. Spearman correlations (or logistic regression) were performed between CRF/muscle strength and the abovementioned variables. Proteins that were significantly correlated with CRF or muscle strength were mapped into protein-protein interaction (PPI) networks using the Search Tool for the Retrieval of Interacting Genes/Proteins (STRING) database. RESULTS: CRF was inversely correlated with clinical severity score ( r = -0.657, P = 0.020). Of 6840 identified tumor proteins, 76 correlated significantly with CRF (19 positively, 57 negatively), whereas 194 correlated with muscle strength (97 positively, 97 negatively). Proteins correlated with CRF were primarily involved in metabolic and structural pathways, including angiotensinogen and elastin. In turn, muscle strength-associated proteins were more abundant and included keratin family proteins (e.g., keratin, type I cytoskeletal 14, and type II cytoskeletal 5), proteins involved in cell adhesion (e.g., desmoglein-1-alpha), and translational regulators (e.g., eukaryotic initiation factor 4A). Network analysis revealed significant enrichment in structural organization and cellular adhesion pathways. CONCLUSIONS: Besides the association of CRF with clinical severity of the tumor, distinct novel tumor proteomic signatures associated with CRF and muscle strength were identified, highlighting potential mechanisms linking physical fitness with childhood cancer biology.

Muscle Strength

Cardiorespiratory training for people with stroke.

RATIONALE: Low levels of cardiorespiratory fitness are common after stroke and are associated with post-stroke disability and increased risk of secondary stroke. Cardiorespiratory training interventions aim to increase cardiorespiratory fitness, improve physical function, reduce disability, and help prevent future strokes. Clinical guidelines recommend exercise as part of lifestyle modification for secondary prevention, and strongly recommend exercise for rehabilitation. This review is one of three reviews that were originally a single review on physical fitness training for stroke. OBJECTIVES: The primary objective of this review was to determine whether cardiorespiratory training after stroke has an effect on death, disability, adverse events, risk factors, fitness, walking, and indices of physical function when compared to a non-exercise control. SEARCH METHODS: In April 2025, we searched nine bibliographic databases and two trials registers to identify studies for inclusion in the review. We checked reference lists, tracked citations, and contacted experts. ELIGIBILITY CRITERIA: We included randomised controlled trials comparing cardiorespiratory training interventions with usual care, no intervention, or a non-exercise intervention in people with stroke. OUTCOMES: Our critical outcomes were death, disability, adverse events, risk factors, fitness, walking, and indices of physical function, assessed at the end of the intervention and the end of the longest follow-up. RISK OF BIAS: We used the Cochrane RoB 1 tool to assess the risk of bias in the included studies. SYNTHESIS METHODS: The studies evaluated different comparisons (e.g. cardiorespiratory training versus no intervention/waiting list control or versus attention control or versus usual care), which we synthesised into a single comparison: cardiorespiratory training versus control. We used random-effects meta-analysis on arm-level data (risk difference (RD) for dichotomous data, and mean difference (MD) or standardised mean difference (SMD) for continuous data, with 95% confidence intervals (CIs)). For outcome data that we did not meta-analyse, we followed Synthesis Without Meta-analysis (SWiM) guidance. We used GRADE to assess the certainty of the evidence for critical outcomes. INCLUDED STUDIES: We included 53 studies (2672 participants, with an average age of 61.9 years). Most studies recruited ambulatory participants in the early subacute (7 days to 3 months) or chronic (> 6 months) phases of recovery. Exercise duration recommendations were met in 49 studies, and frequency recommendations in 48. Twenty-eight studies lacked balanced exposure between groups. Programme duration was 12 weeks or more in 16 studies (maximum: 24 weeks). Sixteen studies had a post-intervention follow-up period (12 weeks to 12 months from baseline). One study planned a six-month follow-up but did not report it. SYNTHESIS OF RESULTS: Cardiorespiratory training does not increase or decrease deaths at the end of intervention (RD 0.00, 95% CI -0.01 to 0.01; 36 studies, 1563 participants; high-certainty evidence) or the end of follow-up (RD -0.00, 95% CI -0.02 to 0.02; 10 studies, 713 participants; high-certainty evidence). Cardiorespiratory training may improve indices of disability slightly at the end of intervention (SMD 0.35, 95% CI 0.12 to 0.57; 17 studies, 1073 participants; very low-certainty evidence), but the evidence is very uncertain. Re-expressed using the Barthel Index (0 to 20), the equivalent effect is MD 1.68, 95% CI 0.59 to 2.74. It is unclear if the effect is clinically meaningful (the minimal clinically important difference (MCID) is +1.85). The effect is unclear at the end of follow-up (SMD -0.14, 95% CI -0.36 to 0.08; 5 studies, 347 participants; low-certainty evidence). Cardiorespiratory training does not increase or decrease the incidence of secondary cardiovascular or cerebrovascular events at the end of intervention (RD -0.00, 95% CI -0.03 to 0.02; 8 studies, 544 participants; high-certainty evidence) and probably does not affect them at the end of follow-up (RD -0.02, 95% CI -0.08 to 0.04; 4 studies, 412 participants; moderate-certainty evidence). It is very uncertain whether cardiorespiratory training affects systolic blood pressure (mmHg) at the end of intervention (MD -2.12, 95% CI -5.81 to 1.57; 9 studies, 535 participants; very low-certainty evidence) (MCID -2 mmHg) or follow-up (MD 0.93, 95% CI -4.30 to 6.16; 3 studies, 155 participants; very low-certainty evidence); the 95% CIs include the MCID. Cardiorespiratory training probably results in a slight improvement in cardiorespiratory fitness (VO2 ml/kg/min) at the end of intervention (MD 2.37, 95% CI 1.39 to 3.36; 13 studies, 608 participants; moderate-certainty evidence); it is unclear if the effect is clinically meaningful (MCID +3.5 ml/kg/min). The effect may be similar at the end of follow-up (MD 2.76, 95% CI 1.36 to 4.16; 5 studies, 237 participants; low-certainty evidence). Subgroup analysis favoured longer interventions. Cardiorespiratory training probably results in a slight increase in comfortable walking speed (metres per second) at the end of intervention (MD 0.08, 95% CI 0.04 to 0.12; 16 studies, 647 participants; moderate-certainty evidence), but the effect is not clinically meaningful (MCID +0.13). The effect is unclear at the end of follow-up (MD 0.02, 95% CI -0.05 to 0.10; 3 studies, 182 participants; low-certainty evidence). Cardiorespiratory training may improve indices of balance at the end of intervention (SMD 0.31, 95% CI 0.15 to 0.47; 18 studies, 772 participants; very low-certainty evidence), but the evidence is very uncertain. Re-expressing using the Berg Balance Scale, the equivalent effect is MD 2.09, 95% CI 1.10 to 3.07; and it is unclear if it is clinically meaningful (MCID of +2). The effect is unclear at the end of follow-up (MD 0.90, 95% CI -1.32 to 3.12; 6 studies, 253 participants; low-certainty evidence). Overall, our certainty about the evidence is limited for most outcomes by imprecision (small number of studies and participants) or risks of bias (e.g. imbalanced exposure doses) or both. AUTHORS' CONCLUSIONS: Cardiorespiratory training after stroke does not affect mortality or the incidence of secondary events at the end of the aerobic exercise training programme or end of follow-up. It may increase fitness, reduce disability, increase walking speed, and improve balance at the end of intervention, but it is unclear if these improvements are clinically meaningful. Further well-designed randomised trials are needed to fully understand the potential benefits and long-term effects of cardiorespiratory training and the optimal exercise prescription. FUNDING: No dedicated funding REGISTRATION: Protocol (and previous versions) available via DOI 10.1002/14651858.CD003316.

Humans

Effects of Time-Based and Distance-Based Repeated Sprint Training on Physical and Physiological Adaptations in Collegiate Basketball Players.

PURPOSE: This study aimed to compare the effects of time-based (TB) and distance-based (DB) repeated-sprint training (RST) on athletic performance adaptations in collegiate basketball players during preseason and to examine whether the 2 training prescriptions produce different levels of homogeneity in the magnitude of individual adaptations. METHODS: Thirty young male basketball players (age = 21.3 [1.4]&#xa0;y) were randomly and equally assigned to 3 groups (n = 10): DB-RST, TB-RST, and an active control group. Participants completed a 7-week RST program performed 3 times per week, consisting of 4 sets of 4 to 9 repetitions per session. The DB-RST group completed each sprint by covering a fixed 35-m distance, whereas the TB-RST group performed each sprint maximally for a fixed 5-second duration. Performance assessments including countermovement vertical jump, 20-m sprint, Illinois change-of-direction speed, reactive strength index, Wingate anaerobic power, and cardiorespiratory fitness were conducted before and after the 7-week training period. RESULTS: Both training groups demonstrated significant performance improvements over the 7-week intervention and relative to the control group (P < .05). Similar gains were observed in the magnitude of adaptations in the countermovement vertical jump, 20-m sprint, Illinois change-of-direction speed, and reactive strength index for the DB-RST and TB-RST groups. Interestingly, the TB-RST group showed more gains than the DB-RST in the magnitude of adaptations in the peak and mean power outputs, as well as cardiorespiratory fitness. Moreover, the TB-RST group showed lower intersubject variability in adaptive responses across the measured performance outcomes following the training intervention. CONCLUSION: Our findings indicate that RST effectively enhances the performance of basketball players, and that implementing a TB-RST protocol is more effective than a DB-RST approach for producing greater adaptations in physiological variables-specifically anaerobic power output and cardiorespiratory fitness-over the 7-week preseason period.

Humans

Exploring the role of successful exercise-induced body weight loss on cardiometabolic health in individuals with metabolic syndrome.

BACKGROUND AND AIM: High-intensity interval training (HIIT) is known to improve cardiorespiratory fitness (i.e., VO2MAX), a key marker of cardiometabolic health in individuals with metabolic syndrome (MetS). Nonetheless, body weight loss is widely recognized as a crucial factor in reducing insulin resistance and improving metabolic risk factors. Thus, we aimed to determine the importance of body weight loss following exercise training on improving MetS. METHODS AND RESULTS: Two hundred and twenty-eight adults (55.3&#xa0;&#xb1;&#xa0;7.9&#xa0;yr) with overweight/obesity (32.5&#xa0;&#xb1;&#xa0;4.6&#xa0;kg&#xb7;m-2) and MetS were randomized to: a) standard health care non-exercise group (CONTROL group, N=58) or b) standard health care plus 16 weeks of HIIT (EXER group, N=170). MetS (MetS z-score), insulin resistance (HOMA-IR), cardiorespiratory fitness (VO2PEAK), maximal cycling power (WPEAK), and body weight/composition were assessed. After intervention, EXER group participants were divided according to their weight loss response to training: i) those achieving the weight loss predicted from estimated exercise energy expenditure (-BW group, n=78; -3.3&#xa0;&#xb1;&#xa0;2.2&#xa0;kg); ii) those not reaching the expected weight loss (=BW group, n=38; -0.7&#xa0;&#xb1;&#xa0;0.5&#xa0;kg); iii) and those who gained weight (+BW group, n=54; 1.1&#xa0;&#xb1;&#xa0;1.0&#xa0;kg). VO2PEAK significantly improved regardless of body weight loss response (-BW, 0.3&#xa0;&#xb1;&#xa0;0.3; =BW, 0.2&#xa0;&#xb1;&#xa0;0.3; +BW, 0.3&#xa0;&#xb1;&#xa0;0.2&#xa0;L&#xb7;min-1; all p&#xa0;<&#xa0;0.001) compared to CONTROL group (0.0&#xa0;&#xb1;&#xa0;0.3&#xa0;L&#xb7;min-1). However, significant improvements in MetS z-score (-0.31&#xa0;&#xb1;&#xa0;0.41) and HOMA-IR (-0.7&#xa0;&#xb1;&#xa0;1.6) were observed only in the -BW group (both p&#xa0;<&#xa0;0.001). CONCLUSIONS: Exercise recommendations should consider that greater improvements in MetS are observed when interventions are accompanied by successful body weight loss. CLINICAL TRIAL REGISTRATION: ClinicalTrials.gov Identifier: NCT05120778.

Humans

Changes in hemoglobin levels and cardiometabolic health in adults with metabolic syndrome - a secondary outcome analysis of a six-month randomized controlled trial.

BACKGROUND: Lower hemoglobin (Hb) levels within the normal range have been associated with favorable metabolic traits in cross-sectional studies. This study investigated whether changes in Hb levels correlated with changes in physiological and cardiometabolic parameters during a six-month behavioral intervention in individuals with metabolic syndrome. METHODS: The&#xa0;six-month randomized controlled trial aimed to reduce sedentary behavior in adults with metabolic syndrome (n&#x2009;=&#x2009;64). Key measurements included fasting blood samples, insulin sensitivity during a hyperinsulinemic-euglycemic clamp, insulin-stimulated liver glucose uptake, liver fat content (LFC), indirect calorimetry, cardiorespiratory fitness, and cardiac function. Correlations&#xa0;between changes in these variables and changes in Hb levels at baseline, three, and six months were examined. RESULTS: Cross-sectionally, higher Hb levels correlated with&#xa0;lower insulin sensitivity (r=-0.35, p&#x2009;=&#x2009;0.005), higher resting O2 consumption (r&#x2009;=&#x2009;0.41, p&#x2009;<&#x2009;0.001), higher resting energy expenditure (r&#x2009;=&#x2009;0.49, p&#x2009;<&#x2009;0.001), higher LFC (r&#x2009;=&#x2009;0.40, p&#x2009;=&#x2009;0.011), and greater&#xa0;left ventricular wall thickness (r&#x2009;=&#x2009;0.42, p&#x2009;=&#x2009;0.001). The intervention did not significantly impact Hb levels, and changes in Hb levels did not correlate with most cardiometabolic changes. However, reduced Hb levels correlated with reduced fasting blood glucose (r&#x2009;=&#x2009;0.29, p&#x2009;=&#x2009;0.032), improved insulin sensitivity (r = -0.26, p&#x2009;=&#x2009;0.045), and increased cardiorespiratory fitness (r = -0.29, p&#x2009;=&#x2009;0.033). CONCLUSIONS: Changes in Hb levels did not consistently correlate with changes in cardiometabolic markers during&#xa0;the intervention. However, reductions in Hb levels may relate to improved insulin sensitivity and fitness. Along&#xa0;cross-sectional correlations, this may be clinically relevant for individuals with metabolic syndrome. Further studies are merited to clarify&#xa0;the role of Hb levels in this high-risk group.

Humans

Physiological and morphological factors associated with successful fencing performance.

The relation between fencing success during a season of intercollegiate competition and various physiological and morphological variables were determined in 14 fencers. Bivariate and multiple regression analysis was used to determine the extent to which the independent variables, individually and collectively, accounted for the variance in two measures of fencing success. The fencing scores correlated significantly with VE max, Vo2 max, the 2 km run, and weight, while there was no significant correlation between the fencing scores and submaximal heart rate at 6 mph, and 1 min steptest score, or other morphological measurements. Cardiorespiratory fitness variables of Vo2 max and VE max accounted for the greatest variance in each of the two fencing scores (57.7 and 58.1%, respectively). Although morphological factors play a role in fencing success, their influence is small when physiological factors are accounted for. Future energy-cost studies are suggested to determine the physiological basis for the relationship between cardiorespiratory fitness and fencing success.

Adipose Tissue

Effects of frequency and duration of training on attrition and incidence of injury.

Eighty-seven male inmates from a state prison and 70 inmates from a county jail volunteered as subjects. The subjects, age 20 to 35 yrs, were assigned randomly into a control or exercise group. Their Vo2max and treadmill performance values were determined before and after a 20 week jogging program. Training intensity was between 85 and 90 percent of maximum heart rate and involved workouts 3 days/week for 15, 30, or 45-min duration at the state prison and for 30-min 1, 3, or 5 days/week at the country jail. Cardiorespiratory fitness improved in direct proportion to frequency and duration of training. Injury, occurred in 22%, 24% and 54% of the 15, 30, and 45-min duration groups and in 0%, 12%, and 39% of the 1, 3, and 5-day/week groups, respectively. Attrition resulting from injury occurred in 0%, 0%, and 17% and in 0%, 4%, and 6% of the same respective groups. Attrition due to lack of interest was similar for all training groups (25%), but was significantly lower in the control groups (10%). Although the results showed a greater increase in cardiorespiratory fitness for the 45-min duration and 5-day/week groups, these programs are not recommened for beginning joggers because of the significantly greater percent of injuries.

Adult

Effect of the Canadian Air Force training programme on a submaximal exercise test.

Validation of the submaximal heart rate/oxygen consumption relationship as an index of 'cardiorespiratory fitness' requires the demonstration of systematic alterations in this relationship concomitant with interventions designed to alter physical fitness. To fulfil those criteria a longitudinal training/de-training study was undertaken. Previously sedentary adult subjects undertook the Canadian Airforce 5BX-XBX exercise programme. Submaximal exercise tests were performed before and after training, and following several weeks cessation of training. A regression line of submaximal heart rate on submaximal oxygen consumption was calculated from the data of each submaximal exercise test. Alterations in the regression lines were examined for each subject individually by testing statistically for difference in slope and elevation between any pair of lines. Subjects who undertook the training/de-training study demonstrated significant systematic alterations in the elevation of the regression lines concomitant with periods of training and de-training. The reproducibility of the submaximal heart rate/oxygen consumption relationship was examined in two additional groups of subjects. Group A repeated a submaximal test on 3 or 4 successive days; Group B were tested before and after 16 weeks of normal activity. Subjects in Group A demonstrated non significant, random alterations in the regression lines on repeated testing and subjects in Group B demonstrated random, though on occasion significant, alterations in the regression lines. The elevation of the submaximal heart rate/oxygen consumption relationship is therefore a valid index for detecting sequential changes in 'cardiorespiratory fitness' in individual subjects.

Adolescent

Effects of physical training and cardiorespiratory physical fitness on exercise-heat tolerance: recent observations.

Most authors agree that physical training in a cool environment improves tolerance to exercise in the heat and the rate of heat acclimatization, but the extent or degree of improvement remains controversial. The best improvement in heat tolerance for men is associated with intensive interval or continuous training at a training intensity greater than 50% of maximal oxygen uptake (Vo2max) for 8-12 weeks; the Vo2max should be increased 15-20%. Far less is known about the appropriate type, intensity and duration of endurance training associated with improved exercise-heat tolerance in women. The major benefits of physical training appear to apply to both short term (less than 2 hrs) or long term (greater than 2 hrs) exercise-heat exposures for men. Generally, individuals with high Vo2max values (previously trained and endurance athletes) are at an advantage in the heat. Utilization of proper physical training appears to produce about 50% of the total adjustment resulting from heat acclimatization, while increased fitness is associated with greater retention of acclimatization in cool environments. Female athletes appear somewhat better able to tolerate exercise in hot environments than nonathletic females while differences between highly trained females and males do not appear as dramatic as once thought.

Acclimatization

Associations Between Health-Related Physical Fitness and Accelerometry-Based Energy Expenditure in Physiotherapy Workers.

BACKGROUND AND PURPOSE: Although it has been assumed that higher physical activity (PA) levels will contribute to better physical fitness (PF) performance, the interplay between these two has yet to be investigated. Moreover, the majority of studies have been presented in children and adolescents, and older adults, while little is known about the correlation in the adult working population of physiotherapists. Therefore, the main purpose of the study was to examine associations between objectively measured PA and health-related PF. METHODS: We recruited 50 physiotherapists (72.6% women) from several public and private settings in the city of Zagreb. The SenseWearArmbandPro3 (SWA), a triaxial accelerometer placed on the nondominant hand for 7 consecutive days, was used to capture total energy expenditure (TEE) and active EE (AEE). Cardiorespiratory fitness included the Harvard step test, and muscular fitness was composed of sit-ups in 60&#xa0;sec and the Handgrip strength. Flexibility was evaluated using the Toe-touch test. RESULTS: TEE and AEE were moderately and positively correlated with the Harvard step test (r&#xa0;=&#xa0;0.65 and 0.62, p&#xa0;<&#xa0;0.001), sit-ups (r&#xa0;=&#xa0;0.70 and 0.59, p&#xa0;<&#xa0;0.001), and the Handgrip strength test (r&#xa0;=&#xa0;0.74 and 0.64, p&#xa0;<&#xa0;0.001). No significant correlation with the Toe-touch test was observed (r&#xa0;=&#xa0;-0.25 and -0.19, p&#xa0;>&#xa0;0.05). When models were adjusted for age, weaker, but significant positive correlations remained. DISCUSSION: The findings suggest that both cardiorespiratory and muscular fitness are positively associated with PA, whereas no statistically significant association with flexibility was detected. Thus, it is not surprising that we obtained moderate to almost strong correlations between TEE and AEE with cardiorespiratory and muscular fitness. CONCLUSIONS: In physiotherapists, TEE and AEE yield moderate correlations with health-related PF, especially for cardiorespiratory and muscular fitness.

Humans