Study I – Researchers performed a six-month, randomized controlled trial to examine the effects of aerobic exercise on cognition and other biomarkers associated with Alzheimer disease pathology for older adults with mild cognitive impairment, and assess the role of sex [gender] as a predictor of response. Participants were 33 adults (17 women) with mild cognitive impairment ranging in age from 55 to 85 (mean age, 70). Participants were randomized to a high-intensity aerobic exercise or a stretching control group. The aerobic group exercised under the supervision of a fitness trainer at 75% to 85% of heart rate reserve for 45 to 60 min/d, 4 d/wk for 6 months. The control group carried out supervised stretching activities according to the same schedule but maintained their heart rate at or below 50% of their heart rate reserve. Before and after the study, glucometabolic and treadmill tests were performed and fat distribution was assessed using dual-energy x-ray absorptiometry. At baseline, month 3, and month 6, blood was collected for assay and cognitive tests were administered. The main outcome measures were performance on Symbol-Digit Modalities, Verbal Fluency, Stroop [a test of attentional vitality and flexibility involving recognition of words printed in different colors] Trails B, Task Switching, Story Recall, and List Learning. Blood tests included fasting plasma levels of insulin, cortisol, brain-derived neurotrophic factor, insulinlike growth factor-I, and beta-amyloids 40 and 42.

Six months of high-intensity aerobic exercise had sex-specific effects on cognition, glucose metabolism, and hypothalamic-pituitary-adrenal axis and trophic activity despite comparable gains in cardiorespiratory fitness and body fat reduction. For women, aerobic exercise improved performance on multiple tests of executive function, increased glucose disposal during the metabolic clamp [in which blood chemistry is manipulated to hold glucose at a fixed level], and reduced fasting plasma levels of insulin, cortisol, and brain-derived neurotrophic factor. For men, aerobic exercise increased plasma levels of insulinlike growth factor I and had a favorable effect only on Trails B performance. The researchers concluded that their results provide support, using rigorous controlled methodology, for a potent nonpharmacologic intervention that improves executive control processes for older women at high risk of cognitive decline. They also note that a sex bias in cognitive response may relate to sex-based differences in glucometabolic and hypothalamic-pituitary-adrenal axis responses to aerobic exercise.

Baker LD, Frank LL, Foster-Schubert K, et al. Effects of Aerobic Exercise on Mild Cognitive Impairment: A Controlled Trial. Arch Neurol. January 1, 2010;67(1):71-79.

Study II – Physical exercise is associated with decreased risk of dementia and Alzheimer disease. Investigators at the Mayo Clinic studied in a population-based case-control study whether physical exercise is associated with decreased risk of mild cognitive impairment (MCI). A total of 1324 subjects without dementia completed a Physical Exercise Questionnaire. An expert consensus panel classified each subject as having normal cognition or MCI based on published criteria. Researchers compared the frequency of physical exercise among 198 subjects with MCI with that among 1126 subjects with normal cognition and adjusted the analyses for age, sex, years of education, medical comorbidity, and depression.

The odds ratios for any frequency of moderate exercise were 0.61 (95% confidence interval, 0.43-0.88; P = .008) for midlife (age range, 50-65 years) and 0.68 (95% confidence interval, 0.49-0.93; P = .02) for late life. The findings were consistent among men and women. Light exercise and vigorous exercise were not significantly associated with decreased risk of MCI. The researchers concluded that in this population-based case-control study, any frequency of moderate exercise performed in midlife or late life was associated with a reduced odds of having MCI.

Geda YE, Roberts RO, Knopman DS, et al. Physical Exercise, Aging, and Mild Cognitive Impairment: A Population-Based Study. Arch Neurol. January 1, 2010;67(1):80-86.

Exercise Helps Knee Pain, But Weight Loss Does Not Add to Pain Relief

In a randomized clinical trial at five general practices in Great Britain, investigators sought to determine whether dietary intervention or knee strengthening exercise, or both, can reduce knee pain and improve knee function in overweight and obese adults. The subjects were 389 men and women aged 45 and over with a body mass index (BMI) of 28 or higher, with self-reported knee pain. Participants were randomized to dietary intervention plus quadriceps strengthening exercises; dietary intervention alone; quadriceps strengthening exercises alone; or advice leaflet only (control group). Dietary intervention consisted of individualized healthy eating advice that would reduce normal intake by 2.5 MJ (600 kcal) a day. Interventions were delivered at home visits over a two year period.

The primary outcome was severity of knee pain scored with the Western Ontario McMaster (WOMAC) osteoarthritis index at 6, 12, and 24 months. Secondary outcomes (all at 24 months) included WOMAC knee physical function and stiffness scores and selected domains on the SF-36 and the hospital anxiety and depression index. 289 (74%) participants completed the trial. There was a significant reduction in knee pain in the knee exercise groups compared with those in the non-exercise groups at 24 months. The absolute effect size (0.25) was moderate. In those randomized to knee exercise improvement in function was evident at 24 months. The mean difference in weight loss at 24 months in the dietary intervention group compared with no dietary intervention was 2.95 kg; for exercise versus no exercise the difference was 0.43 kg. This difference in weight loss was not associated with improvement in knee pain or function but was associated with a reduction in depression.

Jenkinson CM, Doherty M, Avery AJ, et al. Effects of dietary intervention and quadriceps strengthening exercises on pain and function in overweight people with knee pain: randomised controlled trial. BMJ. 2009;339:b3170.

Resistance Training and All-Around Exercise Decrease Musculoskeletal Pain

This study investigated effects of physical exercise on musculoskeletal pain symptoms in all regions of the body, as well as on other musculoskeletal pain in association with neck pain. A single blind randomized controlled trial testing a one-year exercise intervention was performed among 549 office workers; specific neck/shoulder resistance training, all-round physical exercise, or a non-exercise reference intervention. Pain symptoms were determined by questionnaire screening of twelve selected body regions. Case individuals were identified for each body region as those reporting pain intensities at baseline of 3 or more (scale of 0-9) during the last three months. For neck cases specifically, the additional number of pain regions was counted. Intensity of pain decreased significantly more in the neck, low back, right elbow and right hand in cases of the two exercise groups compared with the reference group. The additional number of pain regions in neck cases decreased in the two exercise groups only. In individuals with no or minor pain at baseline, development of pain was minor in all three groups. In conclusion, both specific resistance training and all-round physical exercise for office workers caused better effects than a reference intervention in relieving musculoskeletal pain symptoms in exposed regions of the upper body.

Andersen LL, Christensen KB, Holtermann A, et al. Effect of physical exercise interventions on musculoskeletal pain in all body regions among office workers: A one-year randomized controlled trial. Man Ther. Feb 2010;15(1):100-104.