Can We Identify Who Will Adhere to Long-Term Physical Activity? Signal Detection Methodology as a Potential Aid to Clinical Decision Making

Department of Health Research and Policy, Stanford University School of Medicine, Palo Alto, California 94304-1583, USA.
Health Psychology (Impact Factor: 3.59). 08/1997; 16(4):380-9. DOI: 10.1037//0278-6133.16.4.380
Source: PubMed


Signal detection methodology was used to identify the best combination of predictors of long-term exercise adherence in 269 healthy, initially sedentary adults ages 50-65 years. Less educated individuals who were assigned to supervised home-based exercise of either higher or lower intensity and who were less stressed and less fit at baseline than other individuals had the greatest probability of successful adherence by the 2nd year. Overweight individuals assigned to a group-based exercise program were the least likely to be successful 2 years later. Predictors of short-term (1-year) adherence were generally similar to predictors of 2-year adherence. Signal detection analysis may be useful for identifying subgroups of people at risk for underadherence who subsequently might be targeted for intervention.

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    • "This implies that fitter individuals were more likely to be intrinsically motivated to participate in the exercise program, and this ensuing motivation predicted adherence and physiological outcomes. This result aligns with previous findings showing that less fit individuals may be less likely to adhere to exercise programs (e.g., King et al., 1997). Nonetheless, the prediction was far from perfect, which means that even unfit adults can adhere to and gain positive health benefits from HIT and MICT training if intrinsic motivation can be fostered. "
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    ABSTRACT: Objective: To examine the motivational process through which increases in aerobic capacity and decreases in total body fat are achieved during high-intensity intermittent training (HIT) and moderate-intensity continuous training (MICT) interventions. Method: Eighty-seven physically inactive adults (65% women, age = 42 ± 12, BMI = 27.67 ± 4.99 kg/m2) took part in a 10-week randomized intervention testing group-based HIT, operationalized as repeated sprints of 15-60 s interspersed with periods of recovery cycling ≤ 25 min/session, 3 sessions/wk-1, or MICT, operationalized as cycling at constant workload of ∼65% maximum aerobic capacity (VO2max, 30-45 min/session-1, 5 sessions/wk-1. Assessments of VO2max and total body fat were made pre- and postintervention. Motivation variables were assessed midintervention and class attendance was monitored throughout. Path analysis was employed, controlling for treatment arm and baseline values of VO2max and total body fat. Results: The 2 groups differed in adherence only, favoring HIT. Baseline VO2max predicted intrinsic motivation midintervention. Intrinsic motivation predicted program adherence, which in turn predicted increases in VO2max and decreases in total body fat by the end of the study. Conclusion: Intrinsic motivation in HIT and MICT is positively linked to adherence to these programs, which can facilitate improvements in fitness and body composition. (PsycINFO Database Record
    Health Psychology 09/2015; DOI:10.1037/hea0000260 · 3.59 Impact Factor
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    • "Inclusion criteria include: (1) mild-to-moderate radiographic medial tibiofemoral OA (Kellgren-Lawrence (KL) = 2 or 3); (2) knee neutral or varus aligned knee ( -2° valgus ≤ angle ≤ 10° varus); (3) BMI ≥ 20 kg.m-2 and ≤ 45 kg.m-2; and (4) no participation in formal strength training for more than 30 min.wk-1 in the past 6 months. We exclude people with BMI >45 kg.m-2 because of difficulty in using CT equipment and lower adherence to exercise [36,37] and <20 kg.m-2 because of limited thigh fat. We include only people with neutral (−2° valgus to 2° varus) or moderate varus (≤ 10° varus) alignment and medial knee OA and not predominant lateral compartment or severe patellofemoral (PF) compartment disease because (1) the medial compartment is the most common disease site, and (2) medial progression is strongly associated with moderate varus alignment [38-40], independent of BMI [41]. "
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    ABSTRACT: Muscle loss and fat gain contribute to the disability, pain, and morbidity associated with knee osteoarthritis (OA), and thigh muscle weakness is an independent and modifiable risk factor for it. However, while all published treatment guidelines recommend muscle strengthening exercise to combat loss of muscle mass and strength in knee OA patients, previous strength training studies either used intensities or loads below recommended levels for healthy adults or were generally short, lasting only 6 to 24 weeks. The efficacy of high-intensity strength training in improving OA symptoms, slowing progression, and affecting the underlying mechanisms has not been examined due to the unsubstantiated belief that it might exacerbate symptoms. We hypothesize that in addition to short-term clinical benefits, combining greater duration with high-intensity strength training will alter thigh composition sufficiently to attain long-term reductions in knee-joint forces, lower pain levels, decrease inflammatory cytokines, and slow OA progression. This is an assessor-blind, randomized controlled trial. The study population consists of 372 older (age >= 55 yrs) ambulatory, community-dwelling persons with: (1) mild-to-moderate medial tibiofemoral OA (Kellgren-Lawrence (KL) = 2-3); (2) knee neutral or varus aligned knee ( -2o valgus <= angle <= 10o varus); (3) 20 kg.m-2 >= BMI <= 45 kg.m-2; and (3) no participation in a formal strength-training program for more than 30 minutes per week within the past 6 months. Participants are randomized to one of 3 groups: high-intensity strength training (75-90% 1Repetition Maximum (1RM)); low-intensity strength training (30-40%1RM); or healthy living education. The primary clinical aim is to compare the interventions' effects on knee pain, and the primary mechanistic aim is to compare their effects on knee-joint compressive forces during walking, a mechanism that affects the OA disease pathway. Secondary aims will compare the interventions' effects on additional clinical measures of disease severity (e.g., function, mobility); disease progression measured by x-ray; thigh muscle and fat volume, measured by computed tomography (CT); components of thigh muscle function, including hip abductor strength and quadriceps strength, and power; additional measures of knee-joint loading; inflammatory and OA biomarkers; and health-related quality of life. Test-retest reliability for the thigh CT scan was: total thigh volume, intra-class correlation coefficients (ICC) = 0.99; total fat volume, ICC = 0.99, and total muscle volume, ICC = 0.99. ICC for both isokinetic concentric knee flexion and extension strength was 0.93, and for hip-abductor concentric strength was 0.99. The reliability of our 1RM testing was: leg press, ICC = 0.95; leg curl, ICC = 0.99; and leg extension, ICC = 0.98. Results of this trial will provide critically needed guidance for clinicians in a variety of health professions who prescribe and oversee treatment and prevention of OA-related complications. Given the prevalence and impact of OA and the widespread availability of this intervention, assessing the efficacy of optimal strength training has the potential for immediate and vital clinical impact.Trial registration:NCT01489462.
    BMC Musculoskeletal Disorders 07/2013; 14(1):208. DOI:10.1186/1471-2474-14-208 · 1.72 Impact Factor
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    • "Garcia and King 1991 U.S. Design: Randomized controlled trial Age: 56.4 (4.2) Quality score: 41 Intervention: Personalized exercise prescription class-based or home-based (home-based included regular telephone contact) Outcome measure: Self-report Exercise logs validation through 'vitalogs' Outcome: Exercise performed relative to prescription (EX) Marital status (+) Smoking status (-) Exercise self-efficacy (+) Exercise intervention condition (home-based vs class-based) (+) Age (NS) Gender (NS) Ethnicity (NS) Education (NS) Income (NS) BMI (NS) Self-motivation (NS) Exercise intervention condition (low vs high intensity) (NS) Perceived exertion, enjoyment and convenience of intervention (NS) [28] King et al. 1997 "
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    ABSTRACT: The health benefits of regular physical activity and exercise have been widely acknowledged. Unfortunately, a decline in physical activity is observed in older adults. Knowledge of the determinants of physical activity (unstructured activity incorporated in daily life) and exercise (structured, planned and repetitive activities) is needed to effectively promote an active lifestyle. Our aim was to systematically review determinants of physical activity and exercise participation among healthy older adults, considering the methodological quality of the included studies. Literature searches were conducted in PubMed/Medline and PsycINFO/OVID for peer reviewed manuscripts published in English from 1990 onwards. We included manuscripts that met the following criteria: 1) population: community dwelling healthy older adults, aged 55 and over; 2) reporting determinants of physical activity or exercise. The outcome measure was qualified as physical activity, exercise, or combination of the two, measured objectively or using self-report. The methodological quality of the selected studies was examined and a best evidence synthesis was applied to assess the association of the determinants with physical activity or exercise. Thirty-four manuscripts reporting on 30 studies met the inclusion criteria, of which two were of high methodological quality. Physical activity was reported in four manuscripts, exercise was reported in sixteen and a combination of the two was reported in fourteen manuscripts. Three manuscripts used objective measures, twenty-two manuscripts used self-report measures and nine manuscripts combined a self-report measure with an objective measure. Due to lack of high quality studies and often only one manuscript reporting on a particular determinant, we concluded "insufficient evidence" for most associations between determinants and physical activity or exercise. Because physical activity was reported in four manuscripts only, the determinants of physical activity particularly need further study. Recommendations for future research include the use of objective measures of physical activity or exercise as well as valid and reliable measures of determinants.
    International Journal of Behavioral Nutrition and Physical Activity 12/2011; 8(article 142):142. DOI:10.1186/1479-5868-8-142 · 4.11 Impact Factor
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