Neighborhood ethnic density and disparities in proximal blood donation opportunities.

BACKGROUND: Despite being the largest racial/ethnic minority group in the United States, Hispanic/Latinos (H/L) are significantly underrepresented among blood donors. A lack of proximal blood donation opportunities may be one factor contributing to these disparities. However, few studies have investigated this possibility. STUDY DESIGN AND METHODS: Proprietary data on mobile blood collections in Maricopa County, Arizona, were gathered for the period of January 01, 2022 to April 30, 2022 and paired with census tract information using ArcGIS. Maricopa County encompasses the city of Phoenix with a total population of approximately 4.5 million people, including 1.5 million H/L residents. Blood drive count was regressed on H/L ethnic density and total population, and model estimates were exponentiated to obtain odds ratios (ORs) and 95% confidence intervals (CIs). RESULTS: During the specified period, approximately 27,000 red blood cell units were collected through mobile drives. Consistent with expectations, when controlling for total neighborhood population, each 10% increase in H/L ethnic density lowered the odds of having a blood drive in the corresponding neighborhood by 12% (OR = 0.88, 95% CI (0.83, 0.92), p < .001). DISCUSSION: These findings provide initial evidence of fewer proximal donation opportunities in areas with greater H/L population density which may contribute to H/L underrepresentation in blood donation and the need for more inclusive collection efforts. Improved access to blood collection is modifiable and could help to increase the overall blood supply, enhance the ability to successfully match specific blood antigen needs of an increasingly diverse population, and bring about a more resilient blood system.

Opioid Receptor Mu 1 Gene (OPRM1) A118G Polymorphism and Emotional Modulation of Pain.

Purpose: The A118G polymorphism in the opioid receptor mu 1 gene (OPRM1) is associated with decreased opioid receptor availability, altered emotion, and increased pain. Given that emotions modulate pain (positive emotions inhibit pain, negative emotions enhance pain), we predicted that G allele carriers would experience impaired emotional modulation of pain compared to non-G allele carriers. Patients and Methods: Emotional pictures (ie, erotica, neutral, attack) from the International Affective Picture System were used by permission from the authors to experimentally manipulate emotions in 64 adult participants while painful electrocutaneous stimulations were delivered in a cross-sectional study. Ratings of arousal and valence/pleasure were made in response to pictures, and pain ratings and a physiological measure of spinal nociception (ie, nociceptive flexion reflex, NFR) were collected in response to painful stimulations. Secondary analyses were conducted to examine the relationship between the A118G polymorphism and emotional modulation of pain/NFR. Results: Exposure to emotional pictures elicited similar changes in valence, but G-carriers rated erotic pictures as more arousing. In non-carriers, pain was facilitated by attack pictures and pain and NFR were inhibited by erotic pictures relative to neutral pictures. Among G-carriers, pain was facilitated by negative emotional pictures but there was no pain or NFR inhibition by positive emotional pictures. Conclusion: The altered response to pleasant stimuli further supports the role of opioids in appetitive behavior and describes how the A118G polymorphism may prevent carriers from inhibiting pain during pleasure.

Brain activity associated with quadriceps strength deficits after anterior cruciate ligament reconstruction.

Prolonged treatment resistant quadriceps weakness after anterior cruciate ligament reconstruction (ACL-R) contributes to re-injury risk, poor patient outcomes, and earlier development of osteoarthritis. The origin of post-injury weakness is in part neurological in nature, but it is unknown whether regional brain activity is related to clinical metrics of quadriceps weakness. Thus, the purpose of this investigation was to better understand the neural contributions to quadriceps weakness after injury by evaluating the relationship between brain activity for a quadriceps-dominated knee task (repeated cycles of unilateral knee flexion/extension from 45° to 0°), , and strength asymmetry in individuals returned to activity after ACL-R. Forty-four participants were recruited (22 with unilateral ACL reconstruction; 22 controls) and peak isokinetic knee extensor torque was assessed at 60°/s to calculate quadriceps limb symmetry index (Q-LSI, ratio of involved/uninvolved limb). Correlations were used to determine the relationship of mean % signal change within key sensorimotor brain regions and Q-LSI. Brain activity was also evaluated group wise based on clinical recommendations for strength (Q-LSI < 90%, n = 12; Q-LSI ≥ 90%, n = 10; controls, all n = 22 Q-LSI ≥ 90%). Lower Q-LSI was related to increased activity in the contralateral premotor cortex and lingual gyrus (p < .05). Those who did not meet clinical recommendations for strength demonstrated greater lingual gyrus activity compared to those who met clinical recommendations Q-LSI ≥ 90 and healthy controls (p < 0.05). Asymmetrically weak ACL-R patients displayed greater cortical activity than patients with no underlying asymmetry and healthy controls.

Correction: A 10+10+30 radio campaign is associated with increased infant vaccination and decreased morbidity in Jimma Zone, Ethiopia: A prospective, quasi-experimental trial.

[This corrects the article DOI: 10.1371/journal.pgph.0001002.].

Neural Correlates of Self-Reported Knee Function in Individuals After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Anterior cruciate ligament (ACL) rupture is a common knee injury among athletes and physically active adults. Despite surgical reconstruction and extensive rehabilitation, reinjuries are common and disability levels are high, even years after therapy and return to activity. Prolonged knee dysfunction may result in part from unresolved neuromuscular deficits of the surrounding joint musculature in response to injury. Indeed, "upstream" neurological adaptations occurring after injury may explain these persistent functional deficits. Despite evidence for injury consequences extending beyond the joint to the nervous system, the link between neurophysiological impairments and patient-reported measures of knee function remains unclear. HYPOTHESIS: Patterns of brain activation for knee control are related to measures of patient-reported knee function in individuals after ACL reconstruction (ACL-R). STUDY DESIGN: Cross-sectional study. LEVEL OF EVIDENCE: Level 3. METHODS: In this multicenter, cross-sectional study, participants with unilateral ACL-R (n = 25; 10 men, 15 women) underwent task-based functional magnetic resonance imaging testing. Participants performed repeated cycles of open-chain knee flexion/extension. Neural activation patterns during the movement task were quantified using blood oxygen level-dependent (BOLD) signals. Regions of interest were generated using the Juelich Histological Brain Atlas. Pearson product-moment correlations were used to determine the relationship between mean BOLD signal within each brain region and self-reported knee function level, as measured by the International Knee Documentation Committee index. Partial correlations were also calculated after controlling for time from surgery and sex. RESULTS: Patient-reported knee function was positively and moderately correlated with the ipsilateral secondary somatosensory cortex (r = 0.57, P = 0.005) and the ipsilateral supplementary motor area (r = 0.51, P = 0.01). CONCLUSION: Increased ipsilateral secondary sensorimotor cortical activity is related to higher perceived knee function. CLINICAL RELEVANCE: Central nervous system mechanisms for knee control are related to subjective levels of knee function after ACL-R. Increased neural activity may reflect central neuroplastic strategies to preserve knee functionality after traumatic injury.

Cross-Cultural Adaptation and Psychometric Validation of the Turkish Version of Pain Resilience Scale.

The Pain Resilience Scale (PRS) is a useful tool that evaluates behavioral engagement and adaptively regulates cognitions and emotions despite the pain. This study aimed to translate the PRS to Turkish and investigate its psychometric properties. The Turkish version of PRS was completed online by 332 healthy adults, and a subset of 105 respondents was re-assessed after 7-14 days. The reliability of the adapted measure was evaluated in terms of internal consistency, relative, and absolute test-retest reliability. Validity was evaluated in terms of structural, construct, and known-group validity using positive and negative psychological scales. The Turkish version of PRS has a three-factor structure and its cumulative variance is 78.06%. The total PRS score and its subscales correlated positively with pain self-efficacy, general resilience, and quality of life, and negatively with pain catastrophizing, kinesiophobia, anxiety, depression, and disability. The PRS scores were significantly higher in those with high general resilience (p < 0.001). The PRS had high internal consistency and test-retest reliability. Standard Error of Measurement (SEM) and Minimum Detectable Difference (MDD) were calculated as 2.9 and 8.0, respectively. The Turkish version of PRS is a reliable and valid instrument for measuring pain resilience in terms of behavioral perseverance and cognitive positivity.

Blood donation motivators and barriers reported by young, first-time whole blood donors: Examining the association of reported motivators and barriers with subsequent donation behavior and potential sex, race, and ethnic group differences.

BACKGROUND: A greater understanding of young, first-time donor motivators and barriers is needed to address the ongoing challenge of retaining these essential donors. STUDY DESIGN AND METHODS: Structured interviews conducted with 508 young, first-time whole blood donors [66.1% female; Mean Age = 19.4 (SD = 2.5) years] were coded to identify reported motivators and barriers. Reported motivators and barriers were then examined for their association with attempted donation behavior over a 14-month follow-up, and for potential sex, race, and ethnic group differences in the frequency of endorsement. RESULTS: Prosocial motivation (e.g., altruism) was the most commonly reported motivator and fear (e.g., fainting, needles) was the most commonly reported barrier. Donation behavior was unrelated to reported motivators, but was significantly related to four reported barriers including fear of fainting/dizziness, fear of needles/pain, having personal commitments that conflict with donating, and perceiving oneself as unsuited to donate for health reasons. Sex, racial, and ethnic differences were noted with respect to the percentages of donors reporting several donation-related motivators and barriers. CONCLUSION: The present findings identify donation-related barriers that could be important targets to address in the effort to encourage new young donors and to retain these new donors for the long term. Importantly, these data also highlight the importance of considering individual differences in donor motivation as a function of sex, race, and ethnicity.

Association of Gender, Race, Mechanism of Injury on Alcohol Use, Posttraumatic Stress Disorder, and Depression in Trauma.

BACKGROUND: There is a paucity of literature documenting whether trauma patients with different mechanisms of injury have different rates of hazardous alcohol use and/or risk for depression and posttraumatic stress disorder. OBJECTIVE: The purpose of this article is to determine whether there are associations between mechanism of injury, hazardous drinking, depression, and posttraumatic stress disorder. Secondary objectives were to examine associations prior to and after the onset of the COVID-19 pandemic. METHODS: This is a retrospective cohort study of 5 years of trauma registry data of adult trauma patients (older than 18 years) admitted to a Midwestern Level I trauma center conducted from January 2016 to November 2020. Multivariable logistic regression analyses were performed to explore the association of gender, race, and mechanism of injury on hazardous drinking and posttraumatic stress disorder and depression. RESULTS: A total of 9,392 trauma patients completed the Alcohol Use Disorders Identification Test-Consumption Items to identify hazardous drinking, and 5,012 completed the Injured Trauma Survivor Screen to identify risk for developing posttraumatic stress disorder and/or depression. The proportion of patients screening positive for hazardous drinking was higher for motor vehicle collisions (21.9%) than for gunshot wounds (17.6%) or falls (18.8%; χ2(2) = 14.311, p < .001). Those involved in motor vehicle collisions were also at a higher risk for the development of depression and posttraumatic stress disorder (54.5%) relative to falls (33.5%) but not gunshot wounds (50.7%; χ2(2) = 200.185, p < .001). The impact of COVID-19 revealed increased hazardous drinking, depression, and posttraumatic stress disorder in patients with falls and motor vehicle collisions but not gunshot wounds. CONCLUSIONS: Motor vehicle collision patients are at most risk for hazardous drinking concomitant with risk for depression and posttraumatic stress disorder. These results help focus future research efforts toward interventions that can reduce these risks.

Research participants recruited using online labor markets may feign medical conditions and overreport symptoms: Caveat emptor.

OBJECTIVE: Over the last decade, the use of online labor markets to collect data in health science has grown exponentially. However, self-identification remains the most common method for recruiting specific clinical sub-populations, and this may adversely affect data validity among respondents motivated to feign a condition for financial gain. METHODS: Online respondents who professed taking medication for a specific medical condition (sample 1: diabetes: N = 307; sample 2: pain: N = 506) were asked to upload an image of their prescribed medication. These images were then evaluated to identify authentic and inauthentic responders based on the images submitted. Authentic and inauthentic respondent groups were then compared on a series of condition-specific health measures and attention checks. RESULTS: In the diabetes sample, respondents whose photos were deemed inauthentic passed fewer attention checks and reported poorer physical (e.g., number of comorbidities) and mental health (e.g., diabetes distress) across a wide variety of measures (η2 = 0.014-0.159). Similarly in the pain sample, respondents whose photos were deemed inauthentic reported poorer physical (e.g., pain interference) and mental health (e.g., depression) across a wide variety of measures (η2 = 0.008-0.129). CONCLUSIONS: The present findings suggest that there may be substantial exaggeration of adverse health among online survey respondents who feign health conditions such as diabetes and chronic pain. Hence, in the absence of procedures to verify health status claims, the validity of data from online survey respondents should be viewed with skepticism.

What would it take to convince you to donate? A survey study of the relationship between motivators, barriers, and payment for whole blood, plasma, and platelet donation.

BACKGROUND: With growing discussion about blood donor remuneration, the present study examined the level of payment that may be required to convince individuals to engage in whole blood, plasma, and platelet donations. STUDY DESIGN AND METHODS: Anonymous online surveys were completed by a college sample [n = 490; 76.9% female; Mean Age = 20.3 (SD = 4.9) years; 32.9% whole blood donors] and a ResearchMatch sample [n = 323; 70.6% female; Mean Age = 50.7 (SD = 16.6) years; 82.7% whole blood donors]. Level of payment needed to motivate whole blood, plasma, and platelet donation was examined as a function of donation history, sample, and gender. In addition, path analyses examined associations between donation motivators, barriers, and payment level. RESULTS: Across all types of donation, history of whole blood donation was related to a greater willingness to donate without payment. At the same time, however, sizeable portions of prior donors indicated that monetary payment would convince them to donate whole blood (24%), plasma (51%), or platelets (57%). Across all types of donation, donation-related barriers (i.e., anxiety, fear) were indirectly related to higher payment levels via lower self-efficacy and more negative donation attitudes. Donation-related motivators (i.e., warm glow, regret, and altruism) were indirectly related to lower payment levels via higher self-efficacy and more positive donation attitudes. CONCLUSION: Despite reporting a strong commitment to nonremunerated blood donation, many respondents with and without a history of blood donation indicated that money would convince them to engage in whole blood, plasma, and platelet donation.

A Virtual Reality Game Suite for Graded Rehabilitation in Patients With Low Back Pain and a High Fear of Movement: Within-Subject Comparative Study.

BACKGROUND: Complex movement pathologies that are biopsychosocial in nature (eg, back pain) require a multidimensional approach for effective treatment. Virtual reality is a promising tool for rehabilitation, where therapeutic interventions can be gamified to promote and train specific movement behaviors while increasing enjoyment, engagement, and retention. We have previously created virtual reality-based tools to assess and promote lumbar excursion during reaching and functional gameplay tasks by manipulating the position of static and dynamic contact targets. Based on the framework of graded exposure rehabilitation, we have created a new virtual reality therapy aimed to alter movement speed while retaining the movement-promoting features of our other developments. OBJECTIVE: This study aims to compare lumbar flexion excursion and velocity across our previous and newly developed virtual reality tools in a healthy control cohort. METHODS: A total of 31 healthy participants (16 males, 15 females) took part in 3 gamified virtual reality therapies (ie, Reachality, Fishality, and Dodgeality), while whole-body 3D kinematics were collected at 100 Hz using a 14-camera motion capture system. Lumbar excursion, lumbar flexion velocity, and actual target impact location in the anterior and vertical direction were compared across each virtual reality task and between the 4 anthropometrically defined intended target impact locations using separate 2-way repeated measures analysis of variance models. RESULTS: There was an interaction between game and impact height for each outcome (all P<.001). Post-hoc simple effects models revealed that lumbar excursion was reduced during Reachality and Fishality relative to that during Dodgeality for the 2 higher impact heights but was greater during Reachality than during Fishality and Dodgeality for the lowest impact height. Peak lumbar flexion velocity was greater during Dodgeality than during Fishality and Reachality across heights. Actual target impact locations during Dodgeality and Fishality were lower relative to those during Reachality at higher intended impact locations but higher at lower intended impact locations. Finally, actual target impact location was further in the anterior direction for Reachality compared to that for Fishality and for Fishality relative to that for Dodgeality. CONCLUSIONS: Lumbar flexion velocity was reduced during Fishality relative to that during Dodgeality and resembled velocity demands more similar to those for a self-paced reaching task (ie, Reachality). Additionally, lumbar motion and target impact location during Fishality were more similar to those during Reachality than to those during Dodgeality, which suggests that this new virtual reality game is an effective tool for shaping movement. These findings are encouraging for future research aimed at developing an individualized and graded virtual reality intervention for patients with low back pain and a high fear of movement.

Assessing motivations for non-living and living organ donation among individuals with and without a history of blood donation.

OBJECTIVES: The current study investigated relationships between a history of blood donation, registration as a non-living and living organ donor, and differential motivations. BACKGROUND: Motivational commonalities exist between blood and organ donors, but there is no prior data on the relationships between blood donation history and both living and non-living organ donor registration and motivation. METHODS/MATERIALS: Participants completed online surveys assessing blood donation history, organ donor registration and interest, and motivations related to donation behaviour. RESULTS: Blood donation history was not significantly related to registration as either a non-living organ donor (blood donors = 81.4%; non-blood donors = 76.4%) or as a living organ donor (blood donors = 14.0%; non-blood donors = 10.9%). Further, blood donation history was not related to interest in learning more about being an organ donor. Compared to those not registered as an organ donor, those who were registered reported more positive organ donation motivations, but these relationships were unrelated to prior blood donation history. CONCLUSION: The present findings are consistent with existing research on attitudes, warm glow, and identity as organ donation motivators, and provide novel information regarding the importance of independent assessment of motivations for non-living and living organ donation.

Social Contagion of Vasovagal Symptoms in Blood Donors: Interactions With Empathy.

BACKGROUND: Vasovagal reactions (VVRs) are commonly experienced in medical situations such as blood donation. Many believe that psychosocial contagion can contribute to the development of VVRs, but this is largely clinical lore. PURPOSE: The goal of the present investigation was to examine the physiological effects of observing another experience a reaction, focusing on the potential moderating effects of empathy. METHODS: This study was part of a randomized controlled trial of behavioral techniques on the prevention of VVRs in blood donors. The sample was composed of 530 healthy university students. Measures of symptoms were obtained with the Blood Donation Reactions Inventory (BDRI) and through observation. Physiological variables were measured using respiratory capnometry and a digital blood pressure monitor. The Affective and Cognitive Measure of Empathy was administered to 230 participants. RESULTS: Donors who witnessed another experiencing a reaction were more likely to spontaneously report symptoms during the blood draw, to be treated for a reaction, to score higher on the BDRI, and to exhibit smaller compensatory heart rate increases. Donors with higher affective empathy reported more symptoms, exhibited hyperventilation, and were more likely to be treated. Donors with higher cognitive empathy were less likely to require treatment if they witnessed a reaction. CONCLUSION: These results suggest that psychosocial contagion of physical symptoms can occur. The moderating effects of empathy differed depending on the subtype of empathy. Perhaps a better cognitive understanding of how other people are feeling functions as a coping response, whereas feeling sympathetic about others' distress increases one's own.

A 10+10+30 radio campaign is associated with increased infant vaccination and decreased morbidity in Jimma Zone, Ethiopia: A prospective, quasi-experimental trial.

Mass media interventions have the potential to reach large audiences and influence health behaviours and outcomes. To date, no study has evaluated the effect of a radio-only campaign on infant vaccination coverage, timeliness, and related morbidity in a low-income country. We implemented the "10+10+30" radio campaign involving broadcasting a weekly 10-minute radio drama series on vaccination, followed by a 10-minute discussion by community health workers, and then a 30-minute listener phone-in segment in Jimma Zone, Ethiopia for three months. To assess the impact of 10+10+30, which was aired on a community radio station, we recruited mothers of infants up to 5 weeks old in intervention district clusters that were inside the radio station's reception range (n = 328 dyads) and control district clusters that were outside of the range (n = 332 dyads). Intention-to-treat and per-protocol analyses, adjusted for pre-intervention differences between the districts, were conducted to examine the co-primary outcome of Penta-3 vaccination coverage and timeliness as well as those of other vaccines and outcomes related to infant morbidity. Both intention-to-treat and per-protocol analyses revealed higher vaccine coverage (p<0.001) and more timely vaccine administration (p<0.001) in the intervention district relative to the control district, with infants in the intervention district being 39% more likely to receive a Penta 3 vaccination (adjusted RR: 1.39, p<0.001). In addition, adjusted regression analyses of maternal retrospective reports over a two-week period revealed 80% less infant diarrhoea (RR: 0.20, p<0.001), 40% less fever (RR: 0.60, p<0.001) and 58% less cough (RR: 0.42, p<0.001) in the intervention district relative to the control district. This study provides compelling initial evidence that a radio drama integrated with discussion and phone-in components may improve infant vaccination coverage and timeliness, and may reduce infant morbidity. Randomized controlled trials are needed to confirm and extend these findings with other samples.

Validation of a test meal paradigm to experimentally manipulate meal-related fears: A registered report.

Fear is central to conceptualizations of weight and shape-focused eating disorders. The current study will examine the reliability and validity of a test meal paradigm that varies perceptions of fat content to manipulate fear. Undergraduate women with elevated eating pathology (N = 96) will be randomized to one of three test meal conditions: two "low" fat yogurts, two "high" fat yogurts, or one "high" fat and one "low" fat yogurt. In actuality, all yogurts will have the same fat content. Supporting reliability, we hypothesize that self-reported fear and electrodermal activity (psychophysiological index of fear-related arousal) will exhibit good test-retest reliability over a 48-hr period in the "high" fat/"high" fat and "low" fat/"low" fat conditions. Supporting construct validity, self-reported fear and electrodermal activity will be elevated during the "high" versus "low" fat condition and responses to the "high" fat condition will correlate with fear of food, eating, and weight gain. Supporting discriminant validity, self-reported disgust and anger will be comparable in the "high" and "low" fat conditions and will exhibit weak correlations with trait measures of disgust and anger. This experimental paradigm will allow researchers to manipulate fear in order understand the mechanisms by which fear maintains eating pathology.

Promoting awareness of donation-related iron depletion among high risk blood donors.

BACKGROUND: The potential for iron deficiency is a known blood donor health concern and suggests the need to inform donors about the potential risks of low iron levels as well as strategies to address these risks. STUDY DESIGN AND METHODS: Frequent (n = 904) and young (n = 629) donors were randomly assigned within risk group to either a control (n = 548) or an intervention (n = 985) group. The control group answered questions at baseline and 6-month follow-up regarding their awareness of the risk of donation-related iron depletion and whether they were taking actions to address their iron status. The intervention group answered the same questions at baseline and follow-up, but after completing the baseline survey, they received information regarding their risk of iron depletion and behaviors they could adopt to mitigate this risk. Intervention group participants were also offered the opportunity to develop an action plan to help them supplement their iron intake. RESULTS: The intervention enhanced overall awareness of donation-related iron loss (OR = 1.5, 95% CI 1.171-1.864, p = .001), with no negative impact on retention. Reported iron health behaviors (iron supplementation, speaking with a doctor) showed significant increases when action planning was paired with the educational information. CONCLUSION: These findings suggest that it is possible to increase awareness of donation-related risk for iron depletion without negatively influencing retention, and combining education with encouragement to develop an action plan may increase the likelihood of both retention and behavioral changes to promote healthy iron levels.

Fear is associated with attrition of first-time whole blood donors: A longitudinal examination of donor confidence and attitude as potential mediators.

BACKGROUND: Elevated fear and anxiety regarding donation-related stimuli (e.g., needles, pain, blood, fainting) has been associated with reduced blood donor recruitment and retention. The present longitudinal study tests the notion that this inverse relationship may be accounted for by lower donation confidence and more negative donation attitudes among fearful first-time donors. STUDY DESIGN AND METHODS: In a sample of 1479 first-time whole blood donors [67.9% female; mean age = 19.3 (standard deviation (SD) = 2.5) years], path analyses were conducted to examine relationships among donor ratings of fear of blood draw and donation anxiety obtained approximately 1 week after donation, donation confidence and attitudes assessed approximately 6 weeks later, and donation attempts over the 14 months following the original donation. RESULTS: Path analyses indicated that both fear of blood draws and donation anxiety were associated with fewer attempted donations, and that these effects were indirectly mediated by a combination of lower donor confidence and more negative donation attitudes. CONCLUSION: Because retention of new blood donors is essential to maintain a healthy blood supply, the results of the present study suggest that first-time donors should be assessed for fear and anxiety so that appropriate strategies can be provided to address their concerns, bolster their confidence and attitudes, and ultimately promote their long-term retention.

Results from the blood donor competence, autonomy, and relatedness enhancement (blood donor CARE) randomized trial.

BACKGROUND: This study aimed to promote competence, autonomy, and relatedness among first-time whole blood donors to enhance intrinsic motivation and increase retention. STUDY DESIGN AND METHODS: Using a full factorial design, first-time donors (N = 2002) were randomly assigned to a no-treatment control condition or to one of seven intervention conditions designed to promote donation competence, autonomy, relatedness, a combination of two (e.g., competence and autonomy), or all three constructs. Participants completed donor motivation measures before the intervention and 6 weeks later, and subsequent donation attempts were assessed for 1 year. RESULTS: There was no significant group difference in the frequency of donation attempts or in the number of days to return. Significant effects of group were observed for 10 of the 12 motivation measures, although follow-up analyses revealed significant differences from the control group were restricted to interventions that included an autonomy component. Path analyses confirmed direct associations between interventions involving autonomy and donor motivation, and indirect mediation of donation attempts via stronger donation intentions and lower donation anxiety. CONCLUSION: Among young, first-time, whole blood donors, brief interventions that include support for donor autonomy were associated with direct effects on donor motivation and indirect, but small, effects on subsequent donation behavior.

Heterogeneity of the strength response to progressive resistance exercise training in older adults: Contributions of muscle contractility.

BACKGROUND: Older adults display wide individual variability (heterogeneity) in the effects of resistance exercise training on muscle strength. The mechanisms driving this heterogeneity are poorly understood. Understanding of these mechanisms could permit development of more targeted interventions and/or improved identification of individuals likely to respond to resistance training interventions. Thus, this study assessed potential physiological factors that may contribute to strength response heterogeneity in older adults: neural activation, muscle hypertrophy, and muscle contractility. METHODS: In 24 older adults (72.3 ± 6.8 years), we measured the following parameters before and after 12 weeks of progressive resistance exercise training: i) isometric leg extensor strength; ii) isokinetic (60°/sec) leg extensor strength; iii) voluntary (neural) activation by comparing voluntary and electrically-stimulated muscle forces (i.e., superimposed doublet technique); iv) muscle hypertrophy via dual-energy x-ray absorptiometry (DXA) estimates of regional lean tissue mass; and v) intrinsic contractility by electrically-elicited twitch and doublet torques. We examined associations between physiological factors (baseline values and relative change) and the relative change in isometric and isokinetic muscle strength. RESULTS: Notably, changes in quadriceps contractility were positively associated with the relative improvement in isokinetic (r = 0.37-0.46, p ≤ 0.05), but not isometric strength (r = 0.09-0.21). Change in voluntary activation did not exhibit a significant association with the relative improvements in either isometric or isokinetic strength (r = 0.35 and 0.33, respectively; p > 0.05). Additionally, change in thigh lean mass was not significantly associated with relative improvement in isometric or isokinetic strength (r = 0.09 and -0.02, respectively; p > 0.05). Somewhat surprising was the lack of association between exercise-induced changes in isometric and isokinetic strength (r = 0.07). CONCLUSIONS: The strength response to resistance exercise in older adults appears to be contraction-type dependent. Therefore, future investigations should consider obtaining multiple measures of muscle strength to ensure that strength adaptations are comprehensively assessed. Changes in lean mass did not explain the heterogeneity in strength response for either contraction type, and the data regarding the influence of voluntary activation was inconclusive. For isokinetic contraction, the strength response was moderately explained by between-subject variance in the resistance-exercise induced changes in muscle contractility.