Oxygen uptake plateau: calculation artifact or physiological reality?

PURPOSE: To test whether the oxygen uptake ([Formula: see text]) plateau at [Formula: see text] is simply a calculation artifact caused by the variability of [Formula: see text] or a clearly identifiable physiological event. METHODS: Forty-six male participants performed an incremental ramp and a [Formula: see text] verification test. Variability of the difference between adjacent sampling intervals (difference) and of the slope of the [Formula: see text]-workload relationship (slope) in the submaximal intensity domain were calculated. Workload defined sampling intervals used for the calculation of the difference and slope were systematically increased from 20 to 100 W until the expected risk of false plateau diagnoses based on the Gaussian distribution function was lower than 5%. Overall, more than 1500 differences and slopes were analyzed. Subsequently, frequencies of plateau diagnoses in the submaximal and maximal intensity domains were compared. RESULTS: Variability of the difference and slope decreased with increasing sampling interval (p < 0.001). At a sampling interval of 50 W, the predefined acceptable risk of false plateau diagnoses (≤ 5%) was achieved. At this sampling interval, the actual frequency (1.4%) of false-positive plateau diagnoses did not differ from the expected frequency in the submaximal intensity domain (1.6%; p = 0.491). In contrast, the actual frequency at maximal intensity (35.7%) was significantly higher compared to the submaximal intensity domain (p < 0.001) and even higher than the expected frequency of false-positive diagnoses (p < 0.001). CONCLUSION: The [Formula: see text] plateau at [Formula: see text] represents a physiological event and no calculation artifact caused by [Formula: see text] variability. However, detecting a [Formula: see text] plateau with sufficient certainty requires large sampling intervals.

Quantification of aerobic determinants of performance in post-pubertal adolescent middle-distance runners.

PURPOSE: The use of oxygen cost ([Formula: see text]aero) parameters to predict endurance performance has recently been criticized. Instead, it is suggested that aerobic energy cost ([Formula: see text]) provides greater validity; however, a comparison of these quantification methods has not previously been made. METHODS: Fifty-six male (n = 34) and female (n = 22) competitive adolescent (17 ± 1 years) middle-distance runners participated in a sub-maximal and maximal incremental treadmill test. Running economy (RE) was measured at the speed corresponding to lactate turnpoint, and the three speeds prior. Maximal oxygen uptake ([Formula: see text]O2max), speed at [Formula: see text]O2max and fraction of [Formula: see text]O2max utilized across a range of intensities, and speeds from 0.8, 1.5 and 3 km races were also quantified. RE and fractional utilization were calculated in units of [Formula: see text]aero and [Formula: see text]aero. RESULTS: Multiple linear regression models demonstrated no discernible difference in the predictive capability of RE, fractional utilization and [Formula: see text]O2max when expressed as [Formula: see text]aero or [Formula: see text]aero in both sexes. When plotted as a function of running speed, [Formula: see text]aero displayed a stepwise decrease (F = 11.59, p < 0.001) whereas [Formula: see text]aero exhibited a curvilinear response (F = 4.74, p = 0.015). Differences were also evident in the slopes plotted for %[Formula: see text]O2max and %[Formula: see text]aeromax against running speed (F = 5.38, p = 0.021). CONCLUSIONS: Quantifying aerobic determinants of performance in units of [Formula: see text]aero provides no greater validity compared to [Formula: see text]aero-based measurement. Although both [Formula: see text]aero and [Formula: see text]aero are sensitive to changes in speed, [Formula: see text]aero provides the more valid reflection of the underlying metabolic cost of running. Physiologists should also be aware of the potential differences between expression of aerobic running intensity based upon %[Formula: see text]O2max compared to %[Formula: see text]aeromax.

No acute effects of placebo or open-label placebo treatments on strength, voluntary activation, and neuromuscular fatigue.

PURPOSE: Recent evidence suggests that deception may not be necessary for placebos to improve clinical outcomes. We tested the hypothesis that placebo and open-label placebo (OLP) treatments would acutely improve strength and voluntary activation, as well as minimize neuromuscular fatigue, in untrained participants. METHODS: Twenty-one males (n = 11) and females (n = 10) visited the laboratory on three occasions (placebo, OLP, control) to receive each treatment in a randomized, counter-balanced manner. Trials involved a pretest, a 15-min intervention, and posttests. For the placebo trial, participants were informed that they would be ingesting a capsule that would improve their performance and make them feel more energetic. For the OLP intervention, participants were told that the capsules would have no effects. In "Experiment #1", knee extensor maximal voluntary contraction (MVC) peak torque and percent voluntary activation were evaluated. In "Experiment #2", participants performed 20 consecutive MVCs while surface electromyographic signals were detected from the vastus lateralis. Subjective assessments of energy and perceived exertion were examined. RESULTS: The interventions had no effect on strength or voluntary activation, but energy levels increased following treatments (p = 0.016, η2 = 0.257). Neither treatment influenced neuromuscular fatigue. Though some variables showed moderate-to-large effect sizes, these results were consistent for individuals with lower voluntary activation. CONCLUSION: Placebo and OLP treatments had minimal influence on strength, voluntary activation, and fatigue resistance. As these findings differ from recent reports, we speculate that placebos and OLPs are more likely to enhance muscle function in patient populations seeking medical care.

[Identification of Good-Practice Projects in Promoting Physical Activity - Methods, Pitfalls and Sampled Outcomes]. / Identifikation von Beispielen guter Praxis der Bewegungsförderung ­ Methoden, Fallstricke und ausgewählte Ergebnisse.

The aim of this paper is to identify and show examples of good practice of public health promotion. For this, uniform quality criteria were worked out under consideration of national and international scientific literature.For the identification of examples of good practice, a comparison of different quality criteria was carried out and combined with each other in a first step. In the following step, examples of good practice were identified after a comprehensive search. The choice of the "good-practice" projects is exemplary and lays no claim to completeness.6 main quality criteria (QC) of programs promoting physical activity could be identified in the national and international context. The analysis showed altogether 10 projects which can exemplarily be classified as examples of good practice of the target groups of children and teenagers, adults, older people and people with pre-existing illnesses. These projects, however, show major differences in their (methodological) quality.The analysis reports a lack of "Good-Practice" examples. Deficits lie mainly in documentation and sustainability. Because of incomplete documentation, an assessment as a "Good-Practice" example is only possible to a limited extent; a lot of information, particularly in the evaluation, is missing.

[Background and Methodology of the Development of German Physical Activity Guidelines]. / Hintergrund und methodisches Vorgehen bei der Entwicklung von nationalen Empfehlungen für Bewegung.

This paper describes the process used to develop the physical activity guidelines for German children and adolescents (0-17 years), adults (18-64 years), older adults ≥65 years and adults with chronic diseases. The German physical activity guidelines were developed by an interdisciplinary working group based on existing guidelines using a 3-phased process. Phase 1: Systematic literature searches for current physical activity guidelines; expert consultation-based development of quality criteria. Phase 2: Evaluation of physical activity guidelines based on the quality criteria; identification and content analysis of high-quality guidelines. Phase 3: Synthesis of content analysis and deduction of German physical activity guidelines. Expert consultation generated 28 quality criteria classified into the 4 domains "A: scope and purpose" (3 items), "B: rigour of development" (10 items), "C: clarity and comprehensiveness of content" (12 items), "D: arrangement and presentation" (3 Items). We identified 66 guidelines scoring ≥60% of the possible rating points in domain A and B as high-quality "source-guidelines" (children and adolescents n=4, adults=16, older adults n=9, 7 chronic diseases n=37). Source-guidelines constitute the database for the development of the German physical activity guidelines. The national physical activity guidelines for children and adolescents, adults, older adults and persons with chronic diseases serve as an evidence-based and quality-controlled basis for physical activity promotion in Germany.

[German National Physical Activity Recommendations for Adults and Older Adults: Methods, Database and Rationale]. / Nationale Bewegungsempfehlungen für Erwachsene und ältere Erwachsene ­ Methodisches Vorgehen, Datenbasis und Begründung.

National physical activity recommendations are regarded as crucial elements of comprehensive physical activity promotion strategies. To date, Germany has no such national physical activity recommendations. The aim of this study was to provide physical activity recommendations based on a comprehensive summary of scientific evidence on the relationships between physical activity and a range of health outcomes in adults and older adults. The recommendations were developed in a 3-phase process (systematic literature review, development and use of quality criteria, synthesis of content) based on already existing high-quality guidelines. Based on the analysis of documents included in this study, the following recommendations were formulated. To gain wide-ranging health benefits, adults and older adults should be physically active regularly and avoid inactivity. Adults and older adults should carry out at least 150 min/week moderate intensity or 75 min/week high intensity aerobic activity. Adults and older adults can also reach the recommended amount of physical activity by performing activities in an appropriate combination in both intensity ranges. Optimally, physical activity should be distributed over the week and it can be accumulated in bouts of at least 10 min. Physical activity beyond 150 min/week yields further health benefits. At the same time, physical activity below 150 min/week is associated with meaningful health gains. Accordingly, all adults and older adults should be encouraged to be physically active whenever possible. Adults and older adults should also perform muscle strengthening activities at least twice a week. Regular balance exercises (3 times a week) can reduce the risk of falls in older adults. Adults and older adults should avoid long periods of sitting and should break up sitting time by physical activity. Physical activity can lead to adverse events, such as musculoskeletal injuries, which can be mitigated through appropriate measures. All in all, the benefits of regular physical activity overweigh by far the risks in both adults and older adults.

[Recommendations for Physical Activity and Sedentary Behaviour for Children and Adolescents: Methods, Database and Rationale]. / Empfehlungen für körperliche Aktivität und Inaktivität von Kindern und Jugendlichen ­ Methodisches Vorgehen, Datenbasis und Begründung.

The benefits of physical activity and a reduction of sedentary behaviour in childhood and adolescence are well established.Based on a quality-assured literature review, the German recommendations were updated. Guidelines for infants, toddlers, children of kindergarten and primary school age and youth are clearly depictedIn general, a higher amount of physical activity is associated with more health benefits. Preschool age children should have 180 min of physical activity daily, and from primary school age on, at least 90 min daily are recommended. Sedentary behaviour, especially time in front of screens, is to be reduced to a minimum.

[Recommendations for Physical Activity During and After Pregnancy]. / Bewegungsempfehlungen für Frauen während und nach der Schwangerschaft.

Regular physical activity during and after pregnancy has beneficial effects for mother and child. German recommendations for physical activity during pregnancy are still missing.We searched PubMed (MedLine) for guidelines published between January 2010 and September 2015 on physical activity during and after pregnancy.A systematic literature research identified 29 articles. Recommendations in the context of specific diseases (gestational diabetes, preeclampsia, obesity, hypertension, PCO, incontinence) or intervention programs were excluded. Only 2 articles met the criteria. 2 separate articles summarizing all international recommendations for physical activity during and after pregnancy were included.In order for mother and child to benefit from physical activity, pregnant women without contraindications should be encouraged to participate in regular physical activity or to remain active. Healthy pregnant and postpartum women should exercise for at least 150 min per week (analogically 20-30 min per day on most or all days of the week) in moderate to vigorous aerobic intensity.

[Physical Activity Recommendations for Adults with a Chronic Disease: Methods, Database and Rationale]. / Bewegungsempfehlungen für Erwachsene mit einer chronischen Erkrankung ­ Methodisches Vorgehen, Datenbasis und Begründung.

This paper describes the development of generic physical activity recommendations for adults (18-65 years) with a chronic disease. The physical activity recommendations were developed based on existing recommendations using a 3-phased process. Phase 1: Systematic literature searches for current physical activity recommendations for 7 chronic diseases. Phase 2: Evaluation of physical activity recommendations on the basis of 28 quality criteria; identification and content analysis of high-quality recommendations. Phase 3: Summary of content analysis and deduction of physical activity recommendations for 7 chronic diseases. Synthesis of the 7 recommendations to generate generic German physical activity recommendations for adults with chronic diseases. The quality rating identified 37 high-class physical activity recommendations (n = number); 18 reviews of physical activity recommendations and meta-analysis regarding health effects of physical activity were additionally included (number in brackets): osteoarthrosis of the hip and the knee n=9 (+6), chronic obstructive pulmonary disease (COPD) n=4 (+1), stable ischemic heart disease n=2 (+2), stroke n=8 (+5), major clinical depression n=6 (+0), chronic unspecific low back pain n=5 (+4). Synthesis of content analysis (available recommendations, health effects, dosage and dose-response-effects, risk assessment) led to the development of generic physical activity recommendations for adults with a chronic disease. Physical activity enhances the health of adults with chronic diseases. The benefits of regular physical activity include improved physical functioning, maintenance of independence, enhanced psychosocial well-being and quality of life, improved symptoms and reduced comorbidities. But, people with chronic diseases who have enhanced physical activity levels may also be at increased risk. Nevertheless, adapted, individualized physical activity is safe and with little risk. The generic physical activity recommendations for adults with chronic conditions provide an evidence-based and quality-controlled basis for physical activity promotion of the target group.

[Recommendations for Physical Activity Promotion: Theory and Evidence]. / Empfehlungen für Bewegungsförderung: Theorie und Evidenzbasierung.

This article defines a framework for the development of recommendations for physical activity promotion. It aims to provide a theoretical foundation and rationale for classifications of physical activity promotion and approaches for the evidence base of recommendations. Perspectives from contrasting scientific disciplines were compared regarding their theoretical approach for physical activity promotion and their influence on possible classifications. In addition, various approaches of an evidence base were analyzed and integrated into a differentiated concept for the evidence base of recommendations. From a public health perspective, the use of integrative multi-level-models is fundamental as they can be combined both with different classifications, and individual, social, environmental and policy-based approaches. The evidence base should include the efficacy, effectiveness and cost-effectiveness of an intervention.The scientific and political rationale for recommendations for physical activity promotion can be supported by an explicit theoretical framework and a differentiated concept of an evidence base.

[Quality Criteria for the Conception, Implementation and Evaluation of Interventions for Physical Activity Promotion: A State-Of-The-Art Review]. / Qualitätskriterien für die Konzipierung, Implementierung und Evaluation von Interventionen zur Bewegungsförderung: Ergebnisse eines State-of-the-Art Reviews.

The success of an intervention for physical activity promotion depends not only on the use of an evidence-based approach, but also on the quality of its implementation in practice. Based on current recommendations from scientists and public health institutions, this state-of-the-art review summarizes the quality criteria for the conception, implementation and evaluation of interventions.A systematic literature search was conducted in the electronic databases PubMed and Scopus. Additionally, guidelines from relevant public health institutions were identified via search engines and websites from governmental and nongovernmental organizations. Based on the analysis of selected documents, quality criteria were listed, grouped and categorized.24 documents, published between 2005 and 2015, provided quality criteria for interventions for physical activity promotion. From the selected documents, 18 quality criteria were defined (conception: 7, implementation: 7, evaluation: 4).This review provides evidence on the relevance of quality criteria within certain stages of an intervention. Future studies could compare the effect of quality criteria on the success of an intervention, or approach the topic from a health-economic perspective.

Physical activity in older age: perspectives for healthy ageing and frailty.

Regular physical activity helps to improve physical and mental functions as well as reverse some effects of chronic disease to keep older people mobile and independent. Despite the highly publicised benefits of physical activity, the overwhelming majority of older people in the United Kingdom do not meet the minimum physical activity levels needed to maintain health. The sedentary lifestyles that predominate in older age results in premature onset of ill health, disease and frailty. Local authorities have a responsibility to promote physical activity amongst older people, but knowing how to stimulate regular activity at the population-level is challenging. The physiological rationale for physical activity, risks of adverse events, societal and psychological factors are discussed with a view to inform public health initiatives for the relatively healthy older person as well as those with physical frailty. The evidence shows that regular physical activity is safe for healthy and for frail older people and the risks of developing major cardiovascular and metabolic diseases, obesity, falls, cognitive impairments, osteoporosis and muscular weakness are decreased by regularly completing activities ranging from low intensity walking through to more vigorous sports and resistance exercises. Yet, participation in physical activities remains low amongst older adults, particularly those living in less affluent areas. Older people may be encouraged to increase their activities if influenced by clinicians, family or friends, keeping costs low and enjoyment high, facilitating group-based activities and raising self-efficacy for exercise.

Growing older with health and vitality: a nexus of physical activity, exercise and nutrition.

The preservation of skeletal muscle mass and strength with advancing age are, we propose, critical aspects of ageing with health and vitality. Physical inactivity and poor nutrition are known to accelerate the gradual age-related decline in muscle mass and strength-sarcopenia-however, both are subject to modification. The main purpose of this review is to present the latest, evidence-based recommendations for physical activity and exercise, as well as diet for older adults that would help in preserving muscle mass and strength. We take the position that future physical activity/exercise guidelines need to make specific reference to resistance exercise and highlight the benefits of higher-intensity aerobic exercise training, alongside advocating older adults perform aerobic-based physical activity and household tasks (e.g., carrying groceries). In terms of dietary recommendations, greater emphasis should be placed on optimal rather than minimum protein intakes for older adults. Indeed, guidelines that endorse a daily protein intake of 1.2-1.5 g/kg BM/day, which are levels 50-90 % greater than the current protein Recommendation Dietary Allowance (0.8 g/kg BM/day), are likely to help preserve muscle mass and strength and are safe for healthy older adults. Being cognisant of factors (e.g., reduced appetite) that may preclude older adults from increasing their total daily protein intake, we echo the viewpoint of other active researchers in advocating that protein recommendations for older adults be based on a per meal approach in order to maximize muscle protein synthesis (MPS). On this basis, assuming three meals are consumed daily, a protein dose of 0.4-0.5 g/kg BM should be contained in each meal. We are beginning to understand ways in which to increase the utilization of ingested protein for the stimulation of MPS, namely by increasing the proportion of leucine contained in a given dose of protein, co-ingesting other nutrients (e.g., carbohydrate and fat or supplementation with n-3 polyunsaturated fatty acids) or being physically active prior to protein intake. Clearly, developing simple lifestyle interventions targeted at preserving muscle mass and strength with advancing age is crucial for facilitating longer, healthier lives into older age.

[Cardiovascular prevention and regular physical exercise : Activity and training as the true "polypill"]. / Kardiovaskuläre Prävention und regelmäßige körperliche Aktivität : Bewegung und Training als wahre "polypill".

Guidelines for cardiovascular prevention need to be regularly revised and updated. With respect to physical activity and exercise, many studies with practical relevance have been published in recent years. They are concerned with the evidence of physical activity for prevention of many diseases and the spectrum of indications for applying physical activity for prevention, therapy and rehabilitation. Training recommendations have been developed for the prevention of various diseases according to the FITT rule, which stands for frequency, intensity, time (of session) and type of sports followed by a progression in the amount of training. Recent publications show that moderate exercise with an increase in regular activity (e.g. 10,000 steps per day) is a sufficient approach for risk reduction in many diseases. An as yet unresolved problem is the best approach for effective motivation for physical exercise. The prescription of exercise is an important approach for improving the motivation for physical activity; however, prescribing exercise needs basic knowledge in sports physiology and proper training recommendations. Furthermore, population-based interventions for physical activity are urgently needed to implement more physical activity in the daily routine. The current ESC guidelines provide a great deal of new information to be implemented in the prevention in primary care; however, with regard to physical activity, more comprehensive biological data of physical activity should be presented in order to improve physician's knowledge, thus enhancing the fight against inactivity and sedentary lifestyles as one of the most significant risk factors.

The training-injury prevention paradox: should athletes be training smarter and harder?

BACKGROUND: There is dogma that higher training load causes higher injury rates. However, there is also evidence that training has a protective effect against injury. For example, team sport athletes who performed more than 18 weeks of training before sustaining their initial injuries were at reduced risk of sustaining a subsequent injury, while high chronic workloads have been shown to decrease the risk of injury. Second, across a wide range of sports, well-developed physical qualities are associated with a reduced risk of injury. Clearly, for athletes to develop the physical capacities required to provide a protective effect against injury, they must be prepared to train hard. Finally, there is also evidence that under-training may increase injury risk. Collectively, these results emphasise that reductions in workloads may not always be the best approach to protect against injury. MAIN THESIS: This paper describes the 'Training-Injury Prevention Paradox' model; a phenomenon whereby athletes accustomed to high training loads have fewer injuries than athletes training at lower workloads. The Model is based on evidence that non-contact injuries are not caused by training per se, but more likely by an inappropriate training programme. Excessive and rapid increases in training loads are likely responsible for a large proportion of non-contact, soft-tissue injuries. If training load is an important determinant of injury, it must be accurately measured up to twice daily and over periods of weeks and months (a season). This paper outlines ways of monitoring training load ('internal' and 'external' loads) and suggests capturing both recent ('acute') training loads and more medium-term ('chronic') training loads to best capture the player's training burden. I describe the critical variable-acute:chronic workload ratio-as a best practice predictor of training-related injuries. This provides the foundation for interventions to reduce players risk, and thus, time-loss injuries. SUMMARY: The appropriately graded prescription of high training loads should improve players' fitness, which in turn may protect against injury, ultimately leading to (1) greater physical outputs and resilience in competition, and (2) a greater proportion of the squad available for selection each week.

Call to Action on Making Physical Activity Assessment and Prescription a Medical Standard of Care.

The U.S. population is plagued by physical inactivity, lack of cardiorespiratory fitness, and sedentary lifestyles, all of which are strongly associated with the emerging epidemic of chronic disease. The time is right to incorporate physical activity assessment and promotion into health care in a manner that engages clinicians and patients. In April 2015, the American College of Sports Medicine and Kaiser Permanente convened a joint consensus meeting of subject matter experts from stakeholder organizations to discuss the development and implementation of a physical activity vital sign (PAVS) to be obtained and recorded at every medical visit for every patient. This statement represents a summary of the discussion, recommendations, and next steps developed during the consensus meeting. Foremost, it is a "call to action" for current and future clinicians and the health care community to implement a PAVS in daily practice with every patient.

Firefighter health and fitness assessment: a call to action.

Sudden cardiac deaths experienced by firefighters in the line of duty account for the largest proportion of deaths annually. Several fire service standards for fitness and wellness have been recommended but currently only 30% of U.S. fire departments are implementing programs for this purpose. The Department of Homeland Security Science and Technology Directorate has initiated the Physiological Health Assessment System for Emergency Responders (PHASER) program aiming to reduce these line-of-duty deaths through an integration of medical science and sensor technologies. Confirming previous reports, PHASER comprehensive risk assessment has identified lack of physical fitness with propensity for overexertion as a major modifiable risk factor. We sought to determine if current levels of fitness and cardiovascular disease (CVD) risk factors in a contemporary cohort of firefighters were better than those reported over the past 30 years. Fifty-one firefighters from a Southern California department were characterized for physical fitness and CVD risk factors using standard measures. Overall, physical fitness and risk factors were not different from previous reports of firefighter fitness and most subjects did not achieve recommended fitness standards. Considering the lack of widespread implementation of wellness/fitness programs in the U.S. fire service together with our findings that low physical fitness and the presence of CVD risk factors persist, we issue a call to action among health and fitness professionals to assist the fire service in implementing programs for firefighters that improve fitness and reduce CVD risk factors. Fitness professionals should be empowered to work with fire departments lending their expertise to guide programs that achieve these objectives, which may then lead to reduced incidence of sudden cardiac death or stroke.

[Physical activity and exercise recommendations for cancer patients during rehabilitation]. / Körperliche Aktivität und körperliches Training in der Rehabilitation einer Krebserkrankung.

AIM OF THE WORK: Cancer and its commonly required continuous and intensive medical treatment have a profound and lasting effect on patients' physical, functional, emotional and social wellbeing. In this context the positive comprehensive effects of physical exercise interventions increasingly prove to be promising. The aim of this review is to derive physical exercise recommendations for patients with cancer, especially concerning aerobic and resistance training during rehabilitation, based on the current literature. In a second step the 3 main cancer types breast cancer, prostate cancer and colon cancer and their distinctive features will be addressed briefly. METHODS: A hierarchic literature research was conducted using the medical information portal Medpilot. The evaluation system of the "European Society of Cardiology" was applied in order to evaluate the evidence and compile evidence-based exercise recommendations for patients with cancer. RESULTS: When summing up the current data, physical exercise proves to be efficient, safe and feasible for patients with cancer. Both aerobic and resistance training have a positive influence on a patient's physical, psychological and social level and should therefore be included in every exercise program. CONCLUSION: While the evidence for breast cancer and increasingly also for prostate cancer is strong, research in colon cancer, for example, is still sparse. In order to create precise recommendations regarding the ideal exercise type and dose for the different cancer types during various treatment phases further high quality studies are necessary.

Exercise duration: Independent effects on acute physiologic responses and the need for an individualized prescription.

An individualization of exercise prescription is implemented mainly in terms of intensity but not for duration. To survey the need for an individualized exercise duration prescription, we investigated acute physiologic responses during constant-load exercise of maximal duration (tmax ) and determined so-called duration thresholds. Differences between absolute (min) and relative terms (% tmax ) of exercise duration were analyzed. Healthy young and trained male and female participants (n = 11) performed an incremental exercise test and one tmax constant-load exercise test at a target intensity of 10% of maximal power output below the second lactate turn point (LTP2 ). Blood lactate, heart rate, and spirometric data were measured during all tests. tmax was markedly different across subjects (69.6 ± 14.8 min; range: 40-90 min). However, distinct duration phases separated by duration thresholds (DTh) were found in most measured variables. These duration thresholds (except DTh1) were significantly related to tmax (DTh2: r2  = 0.90, p < 0.0001; DTh3: r2  = 0.98, p < 0.0001) and showed substantial interindividual differences if expressed in absolute terms (DTh2: 24.8 ± 6.0 min; DTh3: 47.4 ± 10.6 min) but not in relative terms (DTh2: 35.4 ± 2.7% tmax ; DTh3: 67.9 ± 2.4% tmax ). Our data showed that (1) maximal duration was individually different despite the same relative intensity, (2) duration thresholds that were related to tmax could be determined in most measured variables, and (3) duration thresholds were comparable between subjects if expressed in relative terms. We therefore conclude that duration needs to be concerned as an independent variable of exercise prescription.