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There is no convincing evidence for the idea that a high power output at the maximal lactate steady state (POTwenty-one recreationally active participants performed stepwise incremental tests on the first and final testing day to measure GE and check for potential test-related training effects in terms of changes in the minimal lactate equivalent power output (∆PO_LEmin), 30-min constant load tests to determine MLSS, a ramp test and verification bout for [Formula: see text]O%[Formula: see text]OThese results challenge the assumption that PO

Introduction Diurnal variations in physical performance can affect athletes' success in competitive sports depending on whether the time of peak performance concurs with the time of competition. The purpose of this systematic review was to investigate the diurnal variation in maximum endurance and strength performance. Methods The databases PubMed, EMBASE, and Web-of-Science were searched from inception to November 2020. The search string was externally reviewed according to PRESS guidelines, the review was conducted in accordance to PRISMA guidelines, and registered beforehand on PROSPERO. Eligibility criteria were that [1] the studies included humans, [2] any kind of maximum endurance or maximum strength test was performed at [3] a minimum of three different times of the day. There were no restrictions regarding study design, participants' sex, age or fitness levels. Results From 10,460 screened articles 63 articles met all three inclusion criteria. Meta-analysis on the harmonizable 29 studies provided evidence for diurnal variations in physical performance. In detail, the overall effect sizes (95% confidence intervals) were 0.23 (0.05; 0.40), 0.73 (0.37; 1.09), 0.39 (0.18; 0.60), and 0.79 (0.28, 1.30) for endurance exercise tests, maximum power output in Wingate-test, handgrip strength, and jump height all in favor of higher performance in the evening. The overall risk of bias in individual studies was moderately high. Conclusions There is strong evidence that anaerobic power as well as jump height are maximal between 13:00 and 19:00. There is some evidence that handgrip strength peaks between 13:00 and 21:00, but only little evidence that there is a time of peak performance in maximum endurance.

Background: Cardiovascular health scores, such as Life’s Simple 7 from the American Heart Association, and the assessment of arterial properties are independently used to determine cardiovascular risk. However, evidence of their association remains scarce, especially in healthy, middle-aged to older populations. Methods: A healthy sample of the Swiss population aged 50–91 years as part of the COmPLETE cohort study was included. Carotid intima–media thickness (cIMT), carotid lumen diameter (cLD), carotid distensibility coefficient (DC), flow-mediated dilation (FMD), and brachial–ankle pulse wave velocity (baPWV) were used to determine arterial properties. The Life’s Simple 7 cardiovascular health score was calculated using seven categories (body-mass index, cholesterol, systolic blood pressure, hemoglobin A1c, smoking status, physical activity, and diet). In accordance with the American Heart Association, for each category, two points were given for an ideal health metric level, intermediate scores one point, and poor scores zero points. Intermediate and ideal health scores corresponded to a total of 5–9 and 10–14 points, respectively. Results: A total of 280 participants (50.7% male) were included. After adjusting for age and sex, an ideal health score was associated with lower cIMT (−0.038 mm, 95% CI: −0.069 mm–−0.007 mm, p = 0.017), lower cLD (−0.28 mm, 95% CI: −0.46 mm–−0.11 mm, p = 0.002), and lower baPWV (−0.05 m/s, 95% CI: −0.08 m/s–−0.02 m/s, p = 0.003). No differences were found for FMD and DC. Conclusions: Even in a healthy sample of middle-aged and older adults, individuals with an ideal cardiovascular health score showed more favorable biomarkers of vascular aging than those with an intermediate score. This stresses the relevance of promoting an optimal lifestyle, even among the healthy population.

Background: Grip strength is used to estimate whole-body strength for health surveillance purposes. Explosive strength is considered important, yet economic measures able to detect early deterioration of neuromuscular capabilities are lacking. Whether handgrip maximum rate of force development (GRFD) or whole-body strength tests are better predictors of lower body power than handgrip maximum strength (GFmax) and their trajectories throughout the life span are unknown. Hypothesis: GRFD should be more closely related to lower body power than GFmax, and its trajectories over the life span should more closely follow that of lower body power. Study Design: Cross-sectional. Level of Evidence: Level 2b. Methods: A total of 613 healthy participants aged 20 to 91 years were tested for countermovement jump peak power, GFmax, handgrip rate of force development, and midthigh pull peak force (MTP). Cubic splines and linear models were built for age trajectories, generalized additive models for quintile curves, and linear regression was used to assess predictive quality. Results: Peak power (Pmax) declined linearly to 60% of young adult level, with GRFD, GFmax, and MTP remaining stable up to age 50 years and then declining more sharply to 52% to 71% of young adult levels. Trajectories were similar for male and female participants. GRFD (β = 0.17) and MTP (β = 0.08) were worse predictors of Pmax than GFmax (β = 0.24) in models adjusted for age, sex, lean body mass, and vigorous physical activity levels. Conclusion: GRFD was not superior to maximum strength in predicting lower body power. For health surveillance purposes, it therefore appears that GFmax tests are more economical and equally good predictors of lower body explosive strength at older age. The data provided can be used as norm values for healthy subjects. Clinical Relevance: Incorporating countermovement jump testing for early detection of declines in explosive capabilities might be advised.

A flattening of the oxygen uptake–work rate relationship at severe exercise indicates the achievement of maximum oxygen uptake $$\left({\text{VO}}_{2\max } \right)$$ VO 2 max . Unfortunately, a distinct plateau $$\left( {{{\text{VO}}}_{2} {\text{pl}}} \right)$$ VO 2 pl at $${{\text{VO}}}_{2\max }$$ VO 2 max is not found in all participants. The aim of this investigation was to critically review the influence of research methods and physiological factors on the $${{\text{VO}}}_{2} {\text{pl}}$$ VO 2 pl incidence. It is shown that many studies used inappropriate definitions or methodical approaches to check for the occurrence of a $${{\text{VO}}}_{2} {\text{pl}}$$ VO 2 pl . In contrast to the widespread assumptions it is unclear whether there is higher $${{\text{VO}}}_{2} {\text{pl}}$$ VO 2 pl incidence in (uphill) running compared to cycling exercise or in discontinuous compared to continuous incremental exercise tests. Furthermore, most studies that evaluated the validity of supramaximal verification phases, reported verification bout durations, which are too short to ensure that $${{\text{VO}}}_{2\max }$$ VO 2 max have been achieved by all participants. As a result, there is little evidence for a higher $${{\text{VO}}}_{2} {\text{pl}}$$ VO 2 pl incidence and a corresponding advantage for the diagnoses of $${{\text{VO}}}_{2\max }$$ VO 2 max when incremental tests are supplemented by supramaximal verification bouts. Preliminary evidence suggests that the occurrence of a $${{\text{VO}}}_{2} {\text{pl}}$$ VO 2 pl in continuous incremental tests is determined by physiological factors like anaerobic capacity, $${{\text{VO}}}_{2}$$ VO 2 -kinetics and accumulation of metabolites in the submaximal intensity domain. Subsequent studies should take more attention to the use of valid $${{\text{VO}}}_{2} {\text{pl}}$$ VO 2 pl definitions, which require a cut-off at ~ 50% of the submaximal $${{\text{VO}}}_{2}$$ VO 2 increase and rather large sampling intervals. Furthermore, if verification bouts are used to verify the achievement of $${{\text{VO}}}_{{2{\text{peak}}}}$$ VO 2 peak /$${{\text{VO}}}_{2\max }$$ VO 2 max , it should be ensured that they can be sustained for sufficient durations.

Endothelial dysfunction represents a diagnostic marker to differentiate disease severity in chronic heart failure (CHF) patients. Retinal vessel phenotyping was applied in CHF patients as it has been acknowledged as a sensitive diagnostic tool to quantify microvascular health and overall cardiovascular risk.The central retinal arteriolar (CRAE) and venular diameter equivalents (CRVE) as well as the retinal microvascular function, quantified by arteriolar (aFID) and venular flicker-light induced dilatation (vFID), were analyzed in 26 CHF patients. These data were compared with 26 age- and sex-matched healthy peers. The effects of an exercise intervention on retinal microvascular health in one CHF patient were investigated to demonstrate potentially beneficial effects of exercise treatment in a case report format as proof of concept.CHF patients showed narrower CRAE (170 ± 16 μm vs. 176 ± 16 μm, p = 0.237) and wider CRVE (217 ± 20 μm vs. 210 ± 17 μm, p = 0.152), resulting in a significantly lower arteriolar-to-venular diameter ratio (AVR, 0.79 ± 0.07 vs. 0.84 ± 0.06, p = 0.004) compared to controls. More strikingly, CHF patients showed significantly lower mean aFID (1.24 ± 1.14% vs. 3.78 ± 1.85%, p 0.001) and vFID (2.89 ± 1.33% vs. 3.88 ± 1.83%, p = 0.033). Twelve weeks of exercise therapy induced wider CRAE (143 ± 1.0 μm vs. 153 ± 0.9 μm), narrower CRVE (183 ± 3.1 μm vs. 180 ± 2.4 μm) and improved aFID (0.67% vs. 1.25%) in a male 78 years old CHF patient.aFID is a sensitive diagnostic tool to quantify microvascular impairments in CHF patients. Exercise treatment in CHF patients has high potential to improve retinal microvascular health as a marker for vascular regeneration and overall risk reduction, which warrants further examination by randomized controlled trials.

Purpose To determine age-dependent cutoff values for secondary exhaustion criteria for a general population free of exercise limiting chronic conditions; to describe the percentage of participants reaching commonly used exhaustion criteria during a cardiopulmonary exercise test (CPET); and to analyze their oxygen uptake at the respective criteria to quantify the impact of a given criterion on the respective oxygen uptake (V˙O2) values. Methods Data from the COmPLETE-Health Study were analyzed involving participants from 20 to 91 yr of age. All underwent a CPET to maximal voluntary exertion using a cycle ergometer. To determine new exhaustion criteria, based on maximal respiratory exchange ratio (RERmax) and age-predicted maximal HR (APMHR), one-sided lower tolerance intervals for the tests confirming V˙O2 plateau status were calculated using a confidence level of 95% and a coverage of 90%. Results A total of 274 men and 252 women participated in the study. Participants were nearly equally distributed across age decades from 20 to >80 yr. A V˙O2 plateau was present in 32%. There were only minor differences in secondary exhaustion criteria between participants exhibiting a V˙O2 plateau and participants not showing a V˙O2 plateau. New exhaustion criteria according to the tolerance intervals for the age group of 20 to 39 yr were: RERmax ≥ 1.13, APMHR210 - age ≥ 96%, and APMHR208 × 0.7 age ≥ 93%; for the age group of 40 to 59 yr: RERmax ≥ 1.10, APMHR210 - age ≥ 99%, and APMHR208 × 0.7 age ≥ 92%; and, for the age group of 60 to 69 yr: RERmax ≥ 1.06, APMHR210 - age ≥ 99%, and APMHR208 × 0.7 age ≥ 89%. Conclusions The proposed cutoff values for secondary criteria reduce the risk of underestimating V˙O2max. Lower values would increase false-positive results, assuming participants are exhausted although, in fact, they are not.

As ageing is a major risk factor for the development of non-communicable diseases, extending healthspan has become a medical and societal necessity. Precise lipid phenotyping that captures metabolic individuality could support healthspan extension strategies. This study applied ‘omic-scale lipid profiling to characterise sex-specific age-related differences in the serum lipidome composition of healthy humans. A subset of the COmPLETE-Health study, composed of 73 young (25.2 ± 2.6 years, 43% female) and 77 aged (73.5 ± 2.3 years, 48% female) clinically healthy individuals, was investigated, using an untargeted liquid chromatography high-resolution mass spectrometry approach. Compared to their younger counterparts, aged females and males exhibited significant higher levels in 138 and 107 lipid species representing 15 and 13 distinct subclasses, respectively. Percentage of difference ranged from 5.8% to 61.7% (females) and from 5.3% to 46.0% (males), with sphingolipid and glycerophophospholipid species displaying the greatest amplitudes. Remarkably, specific sphingolipid and glycerophospholipid species, previously described as cardiometabolically favourable, were found elevated in aged individuals. Furthermore, specific ether-glycerophospholipid and lyso-glycerophosphocholine species displayed higher levels in aged females only, revealing a more favourable lipidome evolution in females. Altogether, age determined the circulating lipidome composition, while lipid species analysis revealed additional findings that were not observed at the subclass level.

The aim was to determine the minimum maximum oxygen uptake (V˙O2max) criteria cut-offs in highly trained athletes (i.e., maximum RER [RERmax], maximum HR [HRmax], maximum RPE [RPEmax], and maximum blood lactate concentration [BLmax]) necessary to determine maximum oxygen uptake (V˙O2max) during cardiopulmonary exercise tests (CPET), by balancing type I and type II errors. A further aim was to investigate if the defined cutoffs would be robust to diurnal and to day-to-day variations.Data from two CPET studies involving young athletes were analyzed. In the first study, 70 male participants performed one CPET until exhaustion to define cutoffs. In the second study, eight males and five females performed one CPET on seven consecutive days at six different times of day (i.e., diurnal variation). The time of the CPET was identical on the sixth and seventh days (i.e., day-to-day variation). To ensure comparability both studies were carried out under the same conditions.Participants' mean V˙O2max was 63.0 ± 5.3 mL·kg·min. RERmax ≥1.10 was reached by 100%, HRmax ≥95% of age-predicted HRmax by 99%, RPEmax ≥19 by 100%, and BLmax ≥8 mmol·L by 100% of participants, respectively. Regarding the intraday variations, latter cutoffs were not reached in two cases for RERmax and in one case for HRmax and BLmax. Intraclass correlations for the day-to-day variability were r = 0.823 for RERmax, r = 0.828 for HRmax, and r = 0.380 for BLmax, respectively.The proposed high cut-off values for secondary criteria provide some assurance that V˙O2max may have been achieved in athletes without increasing type II errors. However, type I errors may still occur indicating that further methods such as V˙O2-plateau or V˙O2-validation may be required.

OBJECTIVES Brachial arterial low flow-mediated constriction (L-FMC) and flow-mediated dilation (FMD) are ultrasound-based biomarkers that emerge into scientific and clinical practice indicating cardiovascular effects of medical and lifestyle-based treatment beyond classical risk factors. This study is the first to provide reference values and to assess the predictive value of L-FMC, FMD and their composite endpoint vasoactive range (VAR) in healthy adults. METHODS L-FMC, FMD and VAR were measured in 457 nonsmoking adults of 20-91 years without chronic diseases, medication, with normal heart function and very low cardiovascular risk. Sex-specific percentiles were calculated and predictive ability for elevated cardiovascular risk was assessed using receiver-operating characteristic (ROC) curves. RESULTS From 20 to 91 years of age, L-FMC increased 86.1 and 105.3%, FMD decreased 63.6 and 47.1% and VAR decreased 58.3 and 55.2% in women and men, respectively. Area under the ROC curves was 0.54 (95% CI = 0.49-0.54) for L-FMC, 0.67 (95% CI = 0.62-0.67) for FMD and 0.72 (95% CI = 0.67-0.72) for VAR (P

Purpose Cardiopulmonary exercise testing (CPET) is an important measurement in clinical practice and its primary outcome, maximal oxygen uptake (V[Combining Dot Above]O2peak), is inversely associated with morbidity and mortality. The purpose of this study is to provide CPET reference values for maximal and submaximal parameters across the adult age spectrum of a healthy European cohort, to compare V[Combining Dot Above]O2peak values with other reference datasets and to analyze the associations between physical activity (PA) levels and CPET parameters. Methods In this cross-sectional study, we prospectively recruited 502 participants (47% female) from 20 to 90 years old. The subjects performed a CPET on a cycle ergometer using a ramp protocol. PA was objectively and continuously measured over 14 days using a triaxial accelerometer. Quantile curves were calculated for CPET parameters. To investigate the associations between CPET parameters and PA levels, linear regression analysis was performed. Results V[Combining Dot Above]O2peak values observed in the group of 20-29 years were 46.6±7.9 and 39.3±6.5 (mL/kg/min) for males and females, respectively. On average, each age category (10-year increments) showed a 10% lower V[Combining Dot Above]O2peak relative to the next younger age category. V[Combining Dot Above]O2peak values of previous studies were, on average 7.5 (mL/kg/min) (20%) lower for males and 6.5 (mL/kg/min) (21%) lower for females. There was strong evidence supporting a positive association between V[Combining Dot Above]O2peak (mL/kg/min) and the level of habitual PA performed at vigorous PA (estimate 0.26; p Conclusion Maximal and submaximal CPET reference values over a large age range are novel and differences to other studies are clinically highly relevant. Objectively measured vigorous-intensity PA showed a strong positive association with higher V[Combining Dot Above]O2peak and other performance-related CPET parameters, supporting the implementation of higher intensity aerobic exercise in health promotion.

ObjectiveThis study compared the robustness of a [Formula: see text]-plateau definition and a verification-phase protocol to day-to-day and diurnal variations in determining the true [Formula: see text]. Further, the additional value of a verification-phase was investigated.MethodsEighteen adults performed six cardiorespiratory fitness tests at six different times of the day (diurnal variation) as well as a seventh test at the same time the sixth test took place (day-to-day variation). A verification-phase was performed immediately after each test, with a stepwise increase in intensity to 50%, 70%, and 105% of the peak power output.ResultsParticipants mean [Formula: see text] was 56 ± 8 mL/kg/min. Gwet's AC1 values (95% confidence intervals) for the day-to-day and diurnal variations were 0.64 (0.22, 1.00) and 0.71 (0.42, 0.99) for [Formula: see text]-plateau and for the verification-phase 0.69 (0.31, 1.00) and 0.07 (-0.38, 0.52), respectively. In 66% of the tests, performing the verification-phase added no value, while, in 32% and 2%, it added uncertain value and certain value, respectively, in the determination of [Formula: see text].ConclusionCompared to [Formula: see text]-plateau the verification-phase shows lower reliability, increases costs and only adds certain value in 2% of cases.

Objective: This study assessed the validity of a consumer activity wristband, a smartphone, and a research-grade accelerometer to measure steps in a free-living setting. Approach: Thirty healthy adults were equipped with two Garmin Vivofit (non-dominant wrist), one iPhone SE (right pants pocket), three ActiGraph wGT3X+ (two on the hip, one on the non-dominant wrist), and one StepWatch (right ankle) and instructed to wear the devices continuously during a 3-day monitoring period. All activities of daily living were recorded in 15-minute intervals in a diary. The StepWatch served as the criterion method and validity was evaluated by comparing each device with the criterion measure using mean absolute percentage errors (MAPE). Main results: The MAPE for the total step count during the 3-day monitoring period was high with a general underestimation of steps by all devices of >20% compared to the criterion measure. The wrist-worn ActiGraph markedly overestimated steps during predominantly low active (public transport or driving, and standing) or even inactive (sitting and lying) activities of daily living. Significance: The overall high MAPE of the devices compared to the StepWatch during step-based activities, likely caused by inaccuracies during short and intermittent bouts of activity, may limit their validity in a free-living setting.

To examine the validity of popular smartphone accelerometer applications and a consumer activity wristband compared to a widely used research accelerometer while assessing the impact of the phone's position on the accuracy of step detection. Twenty volunteers from 2 different age groups (Group A: 18-25 years, n = 10; Group B 45-70 years, n = 10) were equipped with 3 iPhone SE smartphones (placed in pants pocket, shoulder bag, and backpack), 1 Samsung Galaxy S6 Edge (pants pocket), 1 Garmin Vivofit 2 wristband, and 2 ActiGraph wGTX+ devices (worn at wrist and hip) while walking on a treadmill (1.6, 3.2, 4.8, and 6.0 km/h) and completing a walking course. All smartphones included 6 accelerometer applications. Video observation was used as gold standard. Validity was evaluated by comparing each device with the gold standard using mean absolute percentage errors (MAPE). The MAPE of the iPhone SE (all positions) and the Garmin Vivofit was small (

Time-of-day effects in strength performance have been extensively investigated due to their relevance in competitive sports. However, most studies use large measurement intervals making it difficult to monitor potential performance changes throughout the day. Furthermore, previous studies have exclusively focused on how the time of day affects strength on a group level and ignored the individual differences in the times of peak performance. Therefore, the main purpose of this study was to investigate the diurnal and day-to-day variations in isometric and isokinetic leg, arm and trunk strength over six different times of the day. Following a familiarization test, 19 trained males (age: 24.1 ± 2.5 years) performed isometric and isokinetic strength assessments at six different times of the day (7:00, 10:00, 13:00, 16:00, 19:00, and 21:00) with an isokinetic dynamometer. An eighth test session was performed at the same time of the day as the seventh test session to investigate the day-to-day variations and the difference between diurnal and day-to-day variations were compared. All tests were separated by at least 48 h. The start time for the first session was randomized. The mean maximum isometric leg strength was 5.85 ± 0.80 N.kg-1 and 4.99 ± 0.78 N.kg-1at the peak and at the nadir of the day, respectively. The mean difference (95% CI) was 0.86 ± 0.47 N.kg-1 (0.62; 1.10) for the diurnal variation and 0.30 ± 0.42 N.kg-1 (0.09; 0.52) for the day-to-day variation. The mean maximum isometric arm strength was 1.68 ± 0.33 N.kg-1 at the peak and 1.46 ± 0.19 N.kg-1 at the nadir of the day, respectively. The mean difference (95% CI) was 0.21 ± 0.16 N.kg-1 (0.14; 0.29) for the diurnal variation and 0.06 ± 0.05 N.kg-1 (0.03; 0.08) for the day-to-day variation. The linear mixed-effects model showed little evidence for differences in isometric leg strength between the different times of the day (all p-values >0.983). The present study demonstrated that diurnal variations in leg and arm strength are nearly three times higher than the day-to-day variations, but there was only little evidence for a time-of-day effect on a group level. The diurnal variations observed herein without time-of-day effects are suggestive that individuals achieve their peak performance at different times of the day. Therefore, performance tests should be carried out at the same time of the day to ensure comparability. Furthermore, depending on the difference between the time of competition and the time of peak performance, as well as the individual magnitude in diurnal variation, some athletes can have a clear disadvantage.Abbreviation: 95% CI, 95% confidence interval; SD, standard deviation; ICC, intraclass correlation coefficient.

In competitive sports any substantial individual differences in diurnal variations in maximal performance are highly relevant. Previous studies have exclusively focused on how the time of day affects performance and disregarded the maximal individual diurnal variation of performance. Thus, the aims of this study were (1) to investigate the maximum diurnal variation in maximum oxygen uptake (VO2max), (2) to compare the diurnal variation of VO2max during the day to the day-to-day variation in VO2max, and (3) to investigate if there is a time-of-day effect on VO2max. Ten male and seven female athletes (mean VO2max: 58.2 ± 6.9 ml/kg/min) performed six maximal cardiopulmonary exercise tests including a verification-phase at six different times of the day (i.e., diurnal variation) and a seventh test at the same time the sixth test took place (i.e., day-to-day variation). The test times were 7:00, 10:00, 13:00, 16:00, 19:00, and 21:00. The order of exercise tests was the same for all participants to ensure sufficient recovery but the time of day of the first exercise test was randomized. We used paired t-tests to compare the nadir and peak of diurnal variations, day-to-day variations and the difference between diurnal and day-to-day variations. The mean difference in VO2max was 5.0 ± 1.9 ml/kg/min (95% CI: 4.1, 6.0) for the diurnal variation and 2.0 ± 1.0 ml/kg/min (95% CI: 1.5, 2.5) for the day-to-day variation. The diurnal variation was significantly higher than the day-to-day variation with a mean difference of 3.0 ± 2.1 ml/kg/min (95% CI: 1.9, 4.1). The linear mixed effects model revealed no significant differences in VO2max for any pairwise comparison between the different times of the day (all p > 0.11). This absence of a time-of-day effect is explained by the fact that peak VO2max was achieved at different times of the day by different athletes. The diurnal variations have meaningful implications for competitive sports and need to be considered by athletes. However, the results are also relevant to research. To increase signal-to-noise-ratio in intervention studies it is necessary to conduct cardiopulmonary exercise testing at the same time of the day for pre- and post-intervention exercise tests.

ObjectiveThis study compared the robustness of aV˙O2-plateau definition and a verification-phase protocol to day-to-day and diurnal variations in determining the trueV˙O2max. Further, the additional value of a verification-phase was investigated.MethodsEighteen adults performed six cardiorespiratory fitness tests at six different times of the day (diurnal variation) as well as a seventh test at the same time the sixth test took place (day-to-day variation). A verification-phase was performed immediately after each test, with a stepwise increase in intensity to 50%, 70%, and 105% of the peak power output.ResultsParticipants meanV˙O2peakwas 56 ± 8 mL/kg/min. Gwet’s AC1values (95% confidence intervals) for the day-to-day and diurnal variations were 0.64 (0.22, 1.00) and 0.71 (0.42, 0.99) forV˙O2-plateau and for the verification-phase 0.69 (0.31, 1.00) and 0.07 (−0.38, 0.52), respectively. In 66% of the tests, performing the verification-phase added no value, while, in 32% and 2%, it added uncertain value and certain value, respectively, in the determination ofV˙O2max.ConclusionCompared toV˙O2-plateau the verification-phase shows lower reliability, increases costs and only adds certain value in 2% of cases.

Background Wrist-worn accelerometers are increasingly used in epidemiological studies to record physical activity. The accelerometer data are usually only analyzed if the convention for compliant wear time is met (i.e. ≥ 10 h per day) but the algorithms to detect wear time have been developed based on data from hip-worn devices only and have not been tested in a free-living setting. The aim of this study was to validate the automatic wear time detection algorithms of one of the most frequently used devices in a free-living setting. Methods Sixty-eight adults wore one ActiGraph GT3X+ accelerometer on the wrist and one on the hip and additionally recorded wear times for each device separately in a diary. Monitoring phase was during three consecutive days in a free-living setting. Wear time was computed by the algorithms of Troiano and Choi and compared to the diary recordings. Results Mean wear time was over 1420 min per day for both devices on all days. Lin’s concordance correlation coefficient for the wrist-worn wear time was 0.73 (0.60; 0.82) when comparing the diary with Troiano and 0.78 (0.67; 0.86) when comparing the diary with Choi. For hip-worn devices the respective values were 0.23 (0.13; 0.33) for Troiano and 0.92 (0.88; 0.95) for Choi. Mean and standard deviation values for absolute percentage errors for wrist-worn devices were − 1.3 ± 8.1% in Troiano and 0.9 ± 7.7% in Choi. The respective values for hip-worn devices were − 17.5 ± 10% in Troiano and − 0.8 ± 4.6% in Choi. Conclusions Hip worn devices may be preferred due to their higher accuracy in physical activity measurement. Automatic wear-time detection can show high errors in individuals, but on a group level, type I, type II, and total errors are generally low when the Choi algorithm is used. In a real-life setting and participants with a high compliance, the algorithm by Choi is sufficient to distinguish wear time from non-wear time on a group level.

Overweight is a worldwide increasing public health issue. Physical exercise is a useful countermeasure. Overweight individuals choose rather low exercise intensities, but especially high exercise intensities lead to higher energy expenditure and show beneficial health effects compared to lower exercise intensities. However, especially in the morning higher exercise intensities are likely to be avoided due to higher subjective effort. Bright light exposure has shown to increase maximum performance. The aim of this study was to investigate if bright light exposure can also increase self-chosen exercise intensity. We hypothesized that morning bright light exposure increases self-chosen exercise intensity of subsequent exercise through increased mood and reduced sleepiness in overweight individuals. In this randomized controlled single-blind parallel group design, 26 overweight individuals (11 males, 15 females; age 25 ± 5.7 years; body mass index 28.9 ± 2.1 kg/mVO2max: maximum oxygen uptake; 95% CI: 95% confidence interval; SD: standard deviation.

Light has a stimulating effect on physical performance if scheduled according to the chronotype, but dose-dependent effects on performance have not yet been examined. Three groups of healthy men (25.1 ± 3.1 years) were exposed to light for different durations in a parallel group design before a 40-min time-trial. In each group, subjects were exposed to either bright light (BL, 4420 lx) or moderate light (ML, 230 lx) in a randomized order in a crossover design. The durations of light exposure were 120 min prior to and during exercise (2HEX; n = 16), 60 min prior to and during exercise (1HEX; n = 10), or only for 60 min prior to exercise (1H; n = 15). Total work performed during the time-trial in kJ in the 2HEX group was significantly higher in the BL setting (527 kJ) than in ML (512 kJ) (P = 0.002), but not in 1HEX (BL: 485 kJ; ML: 498 kJ) or 1H (BL: 519 kJ; ML: 514 kJ) (P = 0.770; P = 0.485). There was a significant (P = 0.006) positive dose-response relationship between the duration of light exposure and the work performed over the three doses of light exposure. A long duration light exposure is an effective tool to increase total work in a medium length time-trial in subjects normalized for their individual chronotype.

To assess which type of evening light exposure has the greatest effect on reaction time and maximum handgrip strength. These were pre-specified secondary outcomes in a trial which primarily investigated the influence of light on cycling performance. Seventy-four male athletes were allocated at random to either bright light (BRIGHT), monochromatic blue light (BLUE), or a control condition (CONTROL). Light exposure lasted for 60 min and started 17 h after the individual midpoint of sleep. Reaction time, handgrip strength, and melatonin levels were measured before and after the light exposure. We used analysis of covariance to compare the groups with respect to the investigated outcomes. Two participants had to be excluded retrospectively. The remaining 72 participants had a median age of 23 years. The adjusted difference in reaction time was −1 ms [95% confidence interval (CI) −8, 6] for participants in BRIGHT and 2 ms (95% CI −5, 9) for participants in BLUE, both relative to participants in CONTROL. The adjusted difference in handgrip strength was 0.9 kg (95% CI −1.5, 3.3) for participants in BRIGHT and −0.3 kg (95% CI −2.7, 2.0) for participants in BLUE, both relative to participants in CONTROL. After the light exposure, 17% of participants in BRIGHT, 22% in BLUE, and 29% in CONTROL showed melatonin concentrations of 2 pg/ml or higher. The results suggest that bright light might reduce melatonin levels but neither bright nor blue light exposure in the evening seem to improve reaction time or handgrip strength in athletes.