Advances in navigating to the nodule and targeting.

PURPOSE OF REVIEW: The multitude of available platforms and imaging modalities for navigational bronchoscopy, in combination with the various sampling tools that can be used intra-procedurally, is complex. This review seeks to describe the recent developments in peripheral bronchoscopy in regards to navigation, imaging, and sampling target lesions in the pulmonary parenchyma. RECENT FINDINGS: Robotic assisted bronchoscopy has improved navigation to the peripheral airways for sampling of peripheral parenchymal lesions. These navigational platforms use innovative technology utilizing electromagnetic navigation and shape-sensing technology for guidance. The greatest improvement has been the stabilization of the robotic scope in the periphery to allow for accurate sampling. Despite improvements in these platforms, limitations of CT to body divergence continue to impact navigation to the lesion and therefore diagnostic yield of the procedure. Advanced intraprocedural imaging with cone beam CT or augmented fluoroscopy has been a recent focus to improve this area. Further, the adoption of newer sampling tools, such as cryobiopsy, offers the possibility of increased diagnostic yield. SUMMARY: The developments in advanced bronchoscopy will impact the role of biopsy in the diagnosis of peripheral pulmonary parenchymal lesions.

The contribution and interplay of implicit and explicit processes on physical activity behavior: empirical testing of the physical activity adoption and maintenance (PAAM) model.

The adoption and maintenance of physical activity (PA) is an important health behavior. This paper presents the first comprehensive empirical test of the Physical Activity Adoption and Maintenance (PAAM) model, which proposes that a combination of explicit (e.g., intention) and implicit (e.g., habit,, affect) self-regulatory processes is involved in PA adoption and maintenance. Data were collected via online questionnaires in English, German, and Italian at two measurement points four weeks apart. The study included 422 participants (Mage= 25.3, SDage= 10.1; 74.2% women) from Germany, Switzerland, Italy, Canada, and the U.S. The study results largely supported the assumptions of the PAAM model, indicating that intentions and habits significantly mediate the effects of past PA on future PA. In addition, the effect of past PA on future PA was shown to be significant through a mediation chain involving affect and habit. Although the hypothesis that trait self-regulation moderates the intention-behavior relationship was not supported, a significant moderating effect of affect on the same relationship was observed. The results suggest that interventions targeting both explicit and implicit processes may be effective in promoting PA adoption and maintenance.

A mixed method investigation of teacher-identified barriers, facilitators and recommendations to implementing daily physical activity in Ontario elementary schools.

BACKGROUND: Fewer than 17% of children worldwide are meeting the international recommendations for daily physical activity. Since most children are in school for the bulk of their day, the classroom has been identified as an ideal space to incorporate physical activity opportunities. In Ontario (Canada), the Daily Physical Activity (DPA) policy aims to ensure all elementary school children receive a minimum of 20 min of moderate to vigorous physical activity each school day during instructional time. However, a 2015 evaluation found that only half of Ontario teachers were meeting this expectation; this work advocated for additional research to monitor implementation and its predictors and to further identify fidelity recommendations. Thus, the current study investigated contemporary factors influencing DPA fidelity in Ontario elementary schools and provides teacher-identified recommendations to support DPA implementation. METHODS: The first part of the study was a quantitative approach surveying 186 elementary school teachers across Ontario. Descriptive statistics including frequencies and means were used to characterize barriers, facilitators, and recommendations to DPA implementation. Spearman's correlations were used to assess the relation between the likelihood of DPA implementation and intrapersonal factors of gender, teaching experience, prior DPA training and personal physical activity participation. The second part of the study consisted of a qualitative approach using teacher interviews to explore in-depth teachers' recommendations to support DPA implementation. A thematic analysis was used to analyze the transcripts and identify recommendations for DPA. RESULTS: Survey results showed that only 23% of teachers met the mandated 20 min of DPA per day. Barriers to implementation included space and time constraints, inadequate training, student behavioural issues and low self-efficacy. Gender, teaching experience and prior DPA training were not related to the likelihood of DPA implementation. Teachers who rated themselves as more physically fit were more likely to implement DPA. Teacher interviews elucidated key areas for improving DPA implementation including greater DPA training opportunities, resources, community partnerships, accountability and strategies that support school-wide implementation. CONCLUSION: The current study demonstrated that fidelity to the DPA policy in Ontario elementary schools is on the decline. This work highlights unique factors implicated in DPA fidelity and brings to the forefront teacher recommendations to improve DPA implementation.

Exploring Localized Muscle Fatigue Responses at Current Upper-Extremity Ergonomics Threshold Limit Values.

OBJECTIVE: The purpose of this study was to evaluate localized muscle fatigue responses at three upper-extremity ergonomics threshold limit value (TLV) duty cycles. BACKGROUND: Recently, a TLV equation was published to help mitigate excessive development of localized muscle fatigue in repetitive upper limb tasks. This equation predicts acceptable levels of maximal voluntary contraction (% MVC) for a given duty cycle (DC). Experimental validation of this TLV curve has not yet been reported, which can help guide utilization by practitioners. METHOD: Eighteen participants performed intermittent isometric elbow flexion efforts, in three separate counter-balanced sessions, at workloads defined by the American Conference of Governmental Industrial Hygenists' (ACGIH) TLV equation: low DC (20% DC, 29.6% MVC), medium DC (40% DC, 19.7% MVC), and high DC (60% DC, 13.9% MVC). Targeted localized muscle fatigue (LMF) of the biceps brachii was tracked across numerous response variables, including decline in strength (MVC), electromyography (EMG) amplitude and mean power frequency (MnPF), and several psychophysical ratings. RESULTS: At task completion, biceps MnPF and MVC (strength) were significantly different between each TLV workload, with the high DC condition eliciting the largest declines in MnPF and MVC. CONCLUSION: Findings demonstrate that working at different DCs along the ACGIH TLV curve may not be equivalent in preventing excessive LMF. Higher DC workloads elicited a greater LMF response across several response variables. APPLICATION: High DC work of the upper extremity should be avoided to mitigate excess LMF development. Current TLVs for repetitive upper-extremity work may overestimate acceptable relative contraction thresholds, particularly at higher duty cycles.

Effects of Comorbid Developmental Coordination Disorder and Symptoms of Attention Deficit Hyperactivity Disorder on Physical Activity in Children Aged 4-5 Years.

Developmental coordination disorder (DCD) is often comorbid with attention-deficit/hyperactivity disorder (ADHD). While children with DCD engage in less moderate-to-vigorous physical activity (MVPA) compared to typically developing (TD) children, research pertaining to how ADHD affects this relationship is limited. We investigated the effect of ADHD on MVPA among children at risk for DCD (DCDr). 507 children aged 4-5 years (DCDr = 233, TD = 274) participated. Motor skills were assessed using the Movement Assessment Battery for Children-2nd edition (DCDr; ≤ 16th percentile), ADHD symptoms were assessed using the Child Behaviour Checklist, and Actigraph accelerometers measured MVPA over seven days. DCD did not negatively affect MVPA, however, after adjusting for ADHD symptoms, the effect of DCD became significant and was driven by symptoms of inattention. Symptoms of ADHD may be suppressing the negative effects of DCD on MVPA, highlighting the importance of assessing and controlling for ADHD symptoms in this population.

The Home Advantage in the National Basketball Association Conference Finals and Finals Series From 1979 to 2019: A Mediation Analysis of Offensive and Defensive Skills.

This study examined the home advantage effect in decisive National Basketball Association Conference Finals and Finals series playoff games from 1979 to 2019 (the 3-point shot era). We also examined the potential contribution of various offensive- and defensive-based skills and whether these skills mediated the relationship between game status (decisive vs. nondecisive) and outcome (win vs. loss). Overall, we found evidence of a home court advantage with the home team winning 63% of the decisive playoff games and 66% of the nondecisive playoff games. After adjusting for multiple comparisons and regular season win percentage, the home team had significantly more defensive rebounds and steals in Game 5 when trailing 3-1 going into that game. Mediation analyses did not reveal any significant findings when examining the impact of decisive game status on performance through offensive and defensive skills, thus suggesting there are other explanations for the home advantage effect.

Outcomes of systemic targeted therapy in recurrent renal cell carcinoma treated with adjuvant sunitinib.

OBJECTIVE: To assess the efficacy and tolerability of rechallenge with sunitinib and other targeted therapies (TTs) in patitents with relapsed recurrent renal cell carcinoma (RCC) in the advanced setting. METHODS: In this multi-institutional retrospective study, patients with relapsed RCC were rechallenged with sunitinib or other systemic TTs as a first-line therapeutic approach after failed adjuvant sunitinib treatment. Patient characteristics, treatments and clinical outcomes were recorded. The primary endpoint was progression-free survival (PFS). Secondary endpoints were objective response rate (ORR) and overall survival (OS). RESULTS: A total of 34 patients with relapses were recorded, and 25 of these (73.5%) were men. Twenty-five patients were treated with systemic TT: 65% of patients received TT against the vascular endothelial growth factor pathway (including sunitinib), 21.7% received mammalian target of rapamycin inhibitors and 13% received immunotherapy. The median (interquartile range) time to relapse was 20.3 (5.2-20.4) months from diagnosis, and 7.5 months (1.0-8.5) from the end of adjuvant suntinib treatment. At a median follow-up of 23.5 months, 24 of the 25 patients had progressed on first-line systemic therapy. The median PFS was 12.0 months (95% confidence interval [CI] 5.78-18.2). There were no statistical differences in PFS between different treatments or sunitinib rechallenge. PFS was not statistically different in patients relapsing on or after adjuvant suntinib treatment (≤ 6 or >6 months after adjuvant suntinib ending). The ORR was 20.5%. The median OS was 29.1 months (95% CI 16.4-41.8). CONCLUSIONS: Rechallenge with sunitinib or other systemic therapies is still a feasible therapeutic option that provides patients with advanced or metastastic RCC with additional clinical benefits with regard to PFS and OS after failed response to adjuvant sunitinib.

Real-World Assessment of Clinical Outcomes Among First-Line Sunitinib Patients with Clear Cell Metastatic Renal Cell Carcinoma (mRCC) by the International mRCC Database Consortium Risk Group.

BACKGROUND: International Metastatic Renal Cell Carcinoma (mRCC) Database Consortium (IMDC) risk groups are important when considering therapeutic options for first-line treatment. MATERIALS AND METHODS: Adult patients with clear cell mRCC initiating first-line sunitinib between 2010 and 2018 were included in this retrospective database study. Median time to treatment discontinuation (TTD) and overall survival (OS) were estimated using Kaplan-Meier analysis. Outcomes were stratified by IMDC risk groups and evaluated for those in the combined intermediate and poor risk group and separately for those in the intermediate risk group with one versus two risk factors. RESULTS: Among 1,769 patients treated with first-line sunitinib, 318 (18%) had favorable, 1,031 (58%) had intermediate, and 420 (24%) had poor IMDC risk. Across the three risk groups, patients had similar age, gender, and sunitinib initiation year. Median TTD was 15.0, 8.5, and 4.2 months in the favorable, intermediate, and poor risk groups, respectively, and 7.1 months in the combined intermediate and poor risk group. Median OS was 52.1, 31.5, and 9.8 months in the favorable, intermediate, and poor risk groups, respectively, and 23.2 months in the combined intermediate and poor risk group. Median OS (35.1 vs. 21.9 months) and TTD (10.3 vs. 6.6 months) were significantly different between intermediate risk patients with one versus two risk factors. CONCLUSION: This real-world study found a median OS of 52 months for patients with favorable IMDC risk treated with first-line sunitinib, setting a new benchmark on clinical outcomes of clear cell mRCC. Analysis of intermediate risk group by one or two risk factors demonstrated distinct clinical outcomes. IMPLICATIONS FOR PRACTICE: This analysis offers a contemporary benchmark for overall survival (median, 52.1 months; 95% confidence interval, 43.4-61.2) among patients with clear cell metastatic renal cell carcinoma who were treated with sunitinib as first-line therapy in a real-world setting and classified as favorable risk according to International Metastatic Renal Cell Carcinoma Database Consortium (IMDC) risk group classification. This study demonstrates that clinical outcomes differ between IMDC risk groups as well as within the intermediate risk group based on the number of risk factors, thus warranting further consideration of risk group when counseling patients about therapeutic options and designing clinical trials.

Methods and design for the ADAPT study: Application of integrateD Approaches to understanding Physical activity during the Transition to emerging adulthood.

BACKGROUND: The overarching objective of the study is to obtain a comprehensive understanding of the salient factors predicting changes in physical activity (PA) during adolescents' transition into emerging adulthood. Using the Multi-Process Action Control model as our guiding framework, we will examine how implicit and explicit psychological processes along with regulatory practices impact PA change during this major life transition. Additionally, we will use a real-time data capture method called Ecological Momentary Assessment to further investigate how environmental and contextual factors, and momentary psychosocial influences effect PA patterns across this dynamic life stage. METHODS: The ADAPT study is a 4-year project comprised of two interrelated studies. Study I is a large prospective cohort study that will invite all grade 11 students across one large school board (a total of seven secondary schools) to participate by completing an online questionnaire. Using a cluster randomization approach, a subset of students from each school will be invited to participate in Study II, whereby participants will wear an accelerometer and complete Ecological Momentary Assessments 5 times a day over a 7-day study period. For both studies, following baseline assessments, there will be three annual follow-up assessments approximately 12 months apart. DISCUSSION: The current study represents one of the largest longitudinal cohort studies examining PA and its determinants and associated consequences among adolescents transitioning out of high school into emerging adulthood. Findings from this study will provide a much more in-depth understanding of how and why changes in PA behaviour occur across this first major life transition.

Perceptions of Ability Mediate the Effect of Motor Coordination on Aerobic and Musculoskeletal Exercise Performance in Young Children at Risk for Developmental Coordination Disorder.

This study examined the effects of perceptions of motor abilities on aerobic and musculoskeletal exercise performance in young children at risk for developmental coordination disorder (rDCD). The participants (N = 539) were part of a larger cohort study, the Coordination and Activity Tracking in Children (CATCH) study. The Movement Assessment Battery for Children (2nd Edition) was used to determine rDCD children. Perceptions of motor abilities were measured by the Perceived Efficacy and Goals Setting system. Aerobic exercise performance was measured using the Bruce Protocol treadmill test, and musculoskeletal exercise performance was assessed using the standing long jump and the Wingate Anaerobic test. The rDCD children reported lower Perceived Efficacy and Goals Setting scores and performed worse on all exercise performance measures. Perceptions of ability also mediated the relationship between developmental coordination disorder and each exercise performance test. It is concerning that children with low motor coordination report lower perceptions of ability even at a very young age.

Effects of Peer Encouragement on Efficacy Perceptions and Physical Performance in Children.

Social interactions are theorized to inform relation-inferred self-efficacy (RISE), which, in turn, may influence self-efficacy and behavior. This study investigated the effects of peer encouragement on RISE, task self-efficacy, and physical performance. Children (N = 84) were assigned to dyads and randomized to provide peer encouragement to one another or not (control group). Participants completed two endurance handgrip trials, separated by a cognitively demanding task intended to induce mental fatigue and increase the salience of the peer encouragement manipulation. Participants in the experimental group exchanged words of encouragement prior to the second endurance trial, whereas those in the control group did not. The peer encouragement group reported higher RISE and showed increased performance across trials compared with controls. Providing peer encouragement prior to a challenging physical task was associated with more positive RISE perceptions and improved physical performance.

The evolving role of cytoreductive nephrectomy in metastatic renal cell carcinoma.

PURPOSE OF REVIEW: To review the evidence related to cytoreductive nephrectomy in metastatic renal cell carcinoma (mRCC) treated in the targeted therapy era, with a focus on observational studies and randomized trials. RECENT FINDINGS: A number of retrospective observational studies exploring the role of cytoreductive nephrectomy have been reported. These have suggested an association between cytoreductive nephrectomy and survival, with hazard ratio estimates ranging from 0.39 to 0.68 in favour of cytoreductive nephrectomy. In contrast, the CARMENA randomized trial demonstrated that sunitinib alone was noninferior to cytoreductive nephrectomy followed by sunitinib in intermediate-risk and poor-risk patients. The results of the SURTIME trial suggest that initial sunitinib followed by a deferred cytoreductive nephrectomy may also be a reasonable approach in select patients. SUMMARY: On the basis of the evidence to date, there is still a role for cytoreductive nephrectomy in the multimodality treatment of mRCC. Careful patient selection is of paramount importance and discussion in multidisciplinary tumour boards is encouraged. As the treatment landscape of mRCC continues to change, the role of cytoreductive nephrectomy in the modern immuno-oncology era will need to be explored.

A program evaluation of an in-school daily physical activity initiative for children and youth.

BACKGROUND: The school system is one setting in which children's physical activity levels may be increased through daily physical activity (DPA) policies and initiatives. Adherence to DPA policies is typically poor and results are limited in regard to the associated benefits for participating children. Therefore, the purpose of this study was to evaluate a range of psychosocial outcomes following a community-led, in-school DPA initiative for 9-14 year old children and youth. METHODS: This program evaluation examined the impact of a DPA program consisting of 20 min of teacher-led DPA for 20 consecutive weeks. Student outcomes were measured using a questionnaire administered at three time points: baseline, mid-intervention, and post-intervention. A teacher questionnaire regarding program adherence and student behaviour was completed at post-intervention. Mixed effects models were used to test for intervention effects, with random intercepts for students, classes, and schools, as well as fixed effects for age and sex. Due to the large number of outcomes measured, we first conducted an omnibus test of the intervention effect followed by three exploratory analyses examining each outcome separately, associations between outcomes and program adherence, and results from the teacher survey. RESULTS: Thirty classes (N = 19 experimental) from 7 schools participated in the study, with a total of 362 children (n = 265 experimental). There was no significant overall effect of the intervention (z = 0.89, p = 0.38) and the exploratory analyses demonstrated significant differences only for self-esteem and subjective happiness, with the control group slightly increasing relative to the experimental group. Teacher-reported adherence to the program was poor with only 21% of teachers adhering to the program. There was no association between overall adherence and student reported outcomes; however, positive correlations were present between adherence and teacher-reported student behaviour. CONCLUSIONS: The DPA program evaluated here did not improve the psychosocial well-being of elementary school-aged children more than usual practices. However, adherence to the program was poor and it did not have a negative effect on the students. Future work is needed on how best to support DPA implementation in the context of the school day and how student well-being may be positively impacted through school-based physical activity. TRIAL REGISTRATION: Program Evaluation of an in-school Daily Physical Activity Initiative NCT03618927 , August 6, 2018. Retrospectively registered.

Temperature effects on the blood oxygen affinity in sharks.

In fish, regional endothermy (i.e., the capacity to significantly elevate tissue temperatures above ambient via vascular heat exchangers) in the red swimming muscles (RM) has evolved only in a few marine groups (e.g., sharks: Lamnidae, Alopiidae, and teleosts Scombridae). Within these taxa, several species have also been shown to share similar physiological adaptations to enhance oxygen delivery to the working tissues. Although the hemoglobin (Hb) of most fish has a decreased affinity for oxygen with an increase in temperature, some regionally endothermic teleosts (e.g., tunas) have evolved Hbs that have a very low or even an increased affinity for oxygen with an increase in temperature. For sharks, however, blood oxygen affinities remain largely unknown. We examined the effects of temperature on the blood oxygen affinity in two pelagic species (the regionally endothermic shortfin mako shark and the ectothermic blue shark) at 15, 20, and 25 °C, and two coastal ectothermic species (the leopard shark and brown smooth-hound shark) at 10, 15, and 20 °C. Relative to the effects of temperature on the blood oxygen affinity of ectothermic sharks (e.g., blue shark), shortfin mako shark blood was less affected by an increase in temperature, a scenario similar to that documented in some of the tunas. In the shortfin mako shark, this may act to prevent premature oxygen dissociation from Hb as the blood is warmed during its passage through vascular heat exchangers. Even though the shortfin mako shark and blue shark occupy a similar niche, the effects of temperature on blood oxygen affinity in the latter more closely resembled that of the blood in the two coastal shark species examined in this study. The only exception was a small, reverse temperature effect (an increase in blood oxygen affinity with temperature) observed during the warming of the leopard shark blood under simulated arterial conditions, a finding that is likely related to the estuarine ecology of this species. Taken together, we found species-specific differences in how temperature affects blood oxygen affinity in sharks, with some similarities between the regionally endothermic sharks and several regionally endothermic teleost fishes.

Cognitive control exertion leads to reductions in peak power output and [Formula: see text] as well as increased perceived exertion on a graded exercise test to exhaustion.

We investigated effects of a brief (10.5 min) cognitively demanding task on graded exercise test performance. Untrained, university students (N = 15) completed two graded exercise tests in counterbalanced, randomised order. One test was preceded by restful viewing of a documentary video (control); the other by a stop-signal task. Cardiorespiratory functions and perceived exertion were monitored during exercise. Peak power output (W) was lower following the stop-signal task (M = 240.03, SD = 53.37) compared to control (M = 246.03, SD = 52.60), P = 0.002, ηP2 = 0.493, as was [Formula: see text] (P = 0.042, Cohen's d = 0.55). Perceived exertion was significantly higher at 50% (d = 0.77) and 75% (d = 0.83) of iso-time following the cognitive task (Ps ≤ 0.01). Results are consistent with research showing negative carryover effects of cognitively demanding tasks on whole-body endurance performance. Results also support the psychobiological model of exercise as performance of the cognitive task did not affect perceived exertion when exercise task demands were lower, but lead to greater perceived exertion and earlier withdrawal of effort at higher levels of exercise task demand. Findings have implications for understanding psychological determinants of exercise performance and conditions that may lead to underestimation of [Formula: see text].

Modeling Variable Phanerozoic Oxygen Effects on Physiology and Evolution.

Geochemical approximation of Earth's atmospheric O2 level over geologic time prompts hypotheses linking hyper- and hypoxic atmospheres to transformative events in the evolutionary history of the biosphere. Such correlations, however, remain problematic due to the relative imprecision of the timing and scope of oxygen change and the looseness of its overlay on the chronology of key biotic events such as radiations, evolutionary innovation, and extinctions. There are nevertheless general attributions of atmospheric oxygen concentration to key evolutionary changes among groups having a primary dependence upon oxygen diffusion for respiration. These include the occurrence of Devonian hypoxia and the accentuation of air-breathing dependence leading to the origin of vertebrate terrestriality, the occurrence of Carboniferous-Permian hyperoxia and the major radiation of early tetrapods and the origins of insect flight and gigantism, and the Mid-Late Permian oxygen decline accompanying the Permian extinction. However, because of variability between and error within different atmospheric models, there is little basis for postulating correlations outside the Late Paleozoic. Other problems arising in the correlation of paleo-oxygen with significant biological events include tendencies to ignore the role of blood pigment affinity modulation in maintaining homeostasis, the slow rates of O2 change that would have allowed for adaptation, and significant respiratory and circulatory modifications that can and do occur without changes in atmospheric oxygen. The purpose of this paper is thus to refocus thinking about basic questions central to the biological and physiological implications of O2 change over geological time.

Self-control training leads to enhanced cardiovascular exercise performance.

The purpose of the study was to investigate the effects of two weeks of self-control strength training on maximum cardiovascular exercise performance. Forty-one participants completed a cognitive self-control depletion task (Stroop task) followed by a maximal graded cycling test and were randomized to training (maximal endurance contractions of spring handgrip trainers, twice daily) or no-treatment control groups. At follow-up (2 weeks), half of each group completed either a time-matched or trial-matched Stroop task followed by another maximal graded cycling test. Results showed a significant 2-way (training X time) interaction (P < 0.001), and a trend for the 3-way (training X time X cognitive task) interaction (P = 0.07). Decomposition of the interactions revealed that across sessions cycling performance increased in both training groups, did not change in the trial-matched cognitive task control group, and declined in the time-matched control group. We conclude that isometric handgrip training leads to self-control strength adaptations that enhance maximal cardiovascular exercise performance or tolerance of exercise at maximal levels of effort.

Self-Control Strength Depletion Reduces Self-Efficacy and Impairs Exercise Performance.

The purpose of this study was to investigate the role of task self-efficacy as a psychological factor involved in the relationship between self-control depletion and physical endurance. Participants (N = 37) completed two isometric handgrip endurance trials, separated by a Stroop task, which was either congruent (control) or incongruent (causing depletion). Task self-efficacy for the second endurance trial was measured following the Stroop task. Participants in the depletion condition reported lower task self-efficacy and showed a greater reduction in performance on the second endurance trial when compared with controls. Task self-efficacy also mediated the relationship between self-control depletion and endurance performance. The results of this study provide evidence that task self-efficacy is negatively affected following self-control depletion. We recommend that task self-efficacy be further investigated as a psychological factor accounting for the negative change in self-control performance of physical endurance and sport tasks following self-control strength depletion.

Experimental evolution of bet hedging under manipulated environmental uncertainty in Neurospora crassa.

All organisms are faced with environmental uncertainty. Bet-hedging theory expects unpredictable selection to result in the evolution of traits that maximize the geometric-mean fitness even though such traits appear to be detrimental over the shorter term. Despite the centrality of fitness measures to evolutionary analysis, no direct test of the geometric-mean fitness principle exists. Here, we directly distinguish between predictions of competing fitness maximization principles by testing Cohen's 1966 classic bet-hedging model using the fungus Neurospora crassa. The simple prediction is that propagule dormancy will evolve in proportion to the frequency of 'bad' years, whereas the prediction of the alternative arithmetic-mean principle is the evolution of zero dormancy as long as the expectation of a bad year is less than 0.5. Ascospore dormancy fraction in N. crassa was allowed to evolve under five experimental selection regimes that differed in the frequency of unpredictable 'bad years'. Results were consistent with bet-hedging theory: final dormancy fraction in 12 genetic lineages across 88 independently evolving samples was proportional to the frequency of bad years, and evolved both upwards and downwards as predicted from a range of starting dormancy fractions. These findings suggest that selection results in adaptation to variable rather than to expected environments.