Fatigability as a function of physical activity energy expenditure in older adults

Increased fatigue is a predictor of morbidity and mortality in older adults. Fatigability defines a change in performance or self-reported fatigue in response to physical activity (PA). However, the relationship of fatigability to PA-related energy expenditure (PAEE) is unknown. Changes in performance, fatigue, and energy expenditure were measured simultaneously in 17 adults (11 females, 74–94 years old) performing eight standardized PA tasks with various energy expenditure requirements in a whole-room indirect calorimeter. Change in performance was objectively measured using a PA movement monitor and change in fatigue was self-reported on a seven-point scale for each task. Performance and perceived fatigability severity scores were calculated as a ratio of change in performance and fatigue, respectively, and PAEE. We found that change in both objective performance and self-reported fatigue were associated with energy expenditure (Spearman rho = −0.72 and −0.68, respectively, p < 0.001) on a task requiring relatively high level of energy expenditure. The performance and perceived fatigability severity scores were significantly correlated (rho = 0.77, p < 0.001) on this task. In summary, results of this proof of concept pilot study show that both perceived and performance fatigability severity scores are related to PAEE-induced fatigue on a task requiring relatively high level of energy expenditure. We conclude that fatigability severity is a valid measure of PAEE-induced fatigue in older adults.     

Habitual meal frequency and energy intake regulation in partially temporally isolated men.

OBJECTIVE: Assessment of a possible relationship between habitual as well as manipulated meal frequency, blood glucose pattern, macronutrient- and energy intake (EI), and energy intake regulation in partially temporally isolated men. DESIGN: A partially temporally isolated within-subject design assessing energy intake regulation in spite of intervention. Intervention consisted of manipulating meal frequency by offering iso-energetic (1 MJ) preloads high in fat or carbohydrate (CHO), with the same energy density. We have previously shown that after a high-CHO preload, inter-meal-interval was 1 h, while after a high-fat preload intermeal-interval was 2 h. SUBJECTS: Twenty healthy young (18-31 y) normal weight (body mass index (BMI): 22.8+/-1.9 kg/m(2)) men. MEASUREMENTS: On two separate days, each after a different preload: subsequent subjects' responses to the preload, eg manipulated meal frequency; continuous blood glucose levels and blood glucose patterns: macronutrient composition of food intake; EI; appetite ratings; and taste perception. From controlled 3-day food intake diaries: habitual meal frequency; EI; and macronutrient-intake. RESULTS: Accuracy of energy intake regulation is expressed as minimizing the difference in energy intake, despite intervention. The difference in 24 h EI on the two test days after the preloads (r(2)=0.56; P<0.001) was a function of habitual meal frequency. Variation in energy intake was primarily explained by habitual meal frequency (r(2)=0.76; P<0.0001). Adding macronutrient composition and number of blood glucose declines to this increased the explained variation to 86 and 96%, respectively. Percentage energy from CHO or from fat explained the variation in habitual meal frequency (r(2)=0.84; P<0.0001). Adding the total number of blood-glucose declines to this increased the explained variation to 88%, and adding average baseline blood glucose levels, sweetness perception and hunger suppression during preload consumption increased the explained variation to 91%. Manipulated meal frequency was related to habitual meal frequency (r(2)=0.86; P<0.0001) and was a function of the number of transient and dynamic blood glucose declines (r(2)=0.74; P<0.0001). CONCLUSION: Habitual meal frequency is of greater significance in energy intake regulation in healthy young men than manipulated meal frequency. Healthy young men with a high habitual meal frequency showed lower 24 h EI, and a smaller difference in EI after macronutrient specific preloads, compared to those with a low habitual meal frequency, thus showing a more accurate energy intake regulation. Habitual meal frequency is based upon a cluster of related factors including macronutrient composition of the food, sweetness perception, hunger suppression, blood glucose declines and average baseline blood glucose levels.     

Cortical inhibition is reduced following short-term training in young and older adults

The purpose of this study was to investigate age-related differences in short-term training adaptations in cortical excitability and inhibition. Thirty young (21.9 ± 3.1 years) and 30 older (72.9 ± 4.6 years) individuals participated in the study. Each participant was randomly assigned to a control (n = 30) or a resistance training (n = 30) group, with equal numbers of young and older subjects in each group. Participants completed 2 days of testing, separated by 2 weeks during which time the training group participated in resistance training of the ankle dorsiflexor muscles three times per week. During each testing session, transcranial magnetic stimulation was used to generate motor evoked potentials (MEPs) and silent periods in the tibialis anterior. Hoffmann reflexes (H-reflexes) and compound muscle action potentials (M-waves) were also evoked via electrical stimulation of the peroneal nerve. At baseline, young subjects had higher maximum voluntary contraction (MVC) force (p = 0.002), larger M-wave amplitude (p < 0.001), and longer duration silent periods (p = 0.01) than older individuals, with no differences in the maximal amplitude of the MEP (p = 0.23) or H-reflex (p = 0.57). In the trained group, MVC increased in both young (17.4 %) and older (19.8 %) participants (p < 0.001), and the duration of the silent period decreased by ~15 and 12 ms, respectively (p < 0.001). Training did not significantly impact MEP (p = 0.69) or H-reflex amplitudes (p = 0.38). There were no significant changes in any measures in the control group (p ≥ 0.19) across the two testing sessions. These results indicate that a reduction in cortical inhibition may be an important neural adaptation in response to training in both young and older adults.     

Effect of physical activity guidelines on physical function in older adults

OBJECTIVES: To determine whether elderly people who meet national guidelines have higher physical function (PF) scores than those who do not and the effect on functional trajectory when physical activity (PA) levels change from above to below this threshold, or vice versa. DESIGN: Pooled data. SETTING: Two 6‐month randomized controlled trials aimed at increasing PA in adults. PARTICIPANTS: Adults aged 65 to 94 (N=357). INTERVENTION: PA counseling over the telephone and through mailed materials. MEASUREMENTS: Self‐reported PA dichotomized at 150 minutes/week and PF using the Medical Outcomes Study 36‐item Short Form Questionnaire PF subscale. RESULTS: At baseline, individuals reporting 150 minutes or more of moderate PA/week had mean PF scores that were 20.3 points higher than those who did not (P<.001). Change in PA minutes from above threshold to below threshold or from below threshold to above threshold from baseline to 6 months resulted in an average change in PF of ?11.18 (P<.001) and +5.10 (P=.05), respectively. CONCLUSION: These findings suggest that PA is an important predictor of functional status. Older sedentary adults can improve PF by meeting recommended PA levels. Conversely, dropping below recommended PA levels has a deleterious effect on PF. Given the importance of PF in maintenance of independence and quality of life in older adults, adherence to recommended PA guidelines should be endorsed.     

Association of physical activity and visual attention in older adults

Objectives: This study was conducted to examine possible associations between physical activity and visual attention in community-dwelling older adults. Methods: Older adults (age 65-95) completed the Useful Field of View (UFOV (R)) test of visual attention, and they also reported current physical activity levels using the Exercise Participation Questionnaire (EPQ) and the Physical Activity Scale for the Elderly (PASE). Results: UFOV (R) performance was significantly correlated with both measures of physical activity, but some of these effects overlapped with the effects of age. The 21 participants (15%) who reported regular participation on the EPQ were found to have significantly better UFOV (R) scores than the more inactive participants both before and after controlling for age, gender, and visual acuity. Discussion: The preservation of visual attention skills across the life span may be more highly correlated with regular participation in exercise training activities than it is with more general occupational and leisure-related physical activity.     

Vigorous physical activity and cardiovascular risk factors in young adults

There are conflicting data regarding the effects of vigorous physical activity (PA) and cardiovascular disease risk factors. Representative samples of adults aged 20-35 from four northern California cities were studied both cross-sectionally and longitudinally in order to examine the relationships between vigorous PA and selected physiological risk factors. A self-report measure of habitual vigorous PA was validated by pulse rate. There were relationships, in both cross-sectional and longitudinal analyses between self-reported vigorous PA and HDL/LDL ratio, especially for women. Relationships in cross-sectional analyses only were found between PA and diastolic blood pressure, total cholesterol, HDL-cholesterol, triglycerides, and alveolar carbon monoxide. The results of the present study generally tend to confirm investigations of other samples.     

Bilateral index expressions and iEMG activity in older versus young adults

BACKGROUND: This study investigated the hypothesis that expressions of maximal and submaximal bilateral indices would not differ between older and young participants. METHODS: Twenty older (73.3 +/- 4.4 years) and 21 younger (22.4 +/- 0.9 years) participants performed maximal voluntary isometric contractions of the elbow flexor muscles, using the right arm only, left arm only, and both arms simultaneously. The participants were asked to repeat these contractions at what they perceived to be 25%, 50%, and 75% of their maximal voluntary isometric contraction levels. RESULTS: Significant bilateral deficits (p <.05), defined as a bilateral index <0, existed at maximal and submaximal intensities, but the submaximal deficits (14-18%) were larger than the maximal deficits (11%). Normalized integrated electromyographic values tended to be higher for unilateral trials than for bilateral trials at all submaximal intensity levels. There were no significant differences between the older and young participants. CONCLUSIONS: Despite the decrease in the size of fast twitch motor units associated with aging, bilateral deficits exist in older adults, do not differ from those observed for younger adults, and remain larger for submaximal intensities.     

Habitual resistance exercise and endothelial ischemia-reperfusion injury in young adults

Resistance exercise involves muscular contractions that can render downstream tissues ischemic and may precondition the vasculature against ischemia-reperfusion (IR) injury, but it is unknown if habitual resistance exercise protects against IR injury in humans. We determined the magnitude and recovery from endothelial IR injury induced by forearm occlusion in 22 healthy young sedentary and resistance-trained adults. After IR injury, brachial artery flow-mediated dilation (FMD) significantly decreased by 36% in sedentary, but not resistance-trained subjects and fully recovered within 45 min. Though HDL-cholesterol, handgrip strength and systolic blood pressure were significantly associated with FMD 15 min after IR injury, the change in FMD from before to 15 min after IR injury was not associated with any subject characteristics. These results are consistent with the notion that habitual resistance exercise may protect against endothelial IR injury in young adults, presumably through effects analogous to ischemic preconditioning.     

Association between physical activity and cognition in Mexican and Korean older adults

IntroductionAs the world's population ages, the prevalence of cognitive impairment associated with age increases. This increase is particularly pronounced in Asia and South-America. The objective of this study was to investigate separately the longitudinal association of physical activity and cognitive function in; older adults in Mexico and South Korea.Materials and MethodsThis is a secondary analysis of two surveys, The Mexican Health and aging Study (MHAS) (n = 5853) and Korean Longitudinal Study of aging (KLoSA) (n = 5188), designed to study the aging process of older adults living in Mexico and South Korea. Participants older than 50 years were selected from rural and urban areas achieving a representative sample. Physical activity was assessed using self-report. Cognition was assessed using Cross-Cultural Cognitive Examination (CCCE) and Minimental state examination (MMSE) in Mexico and South Korea respectively. Here we investigate the longitudinal association between physical activity and cognition during 3 years for MHAS and 4 years for KLoSA using multiple linear regression analyses.ResultsThe prevalence of physical activity was 40.68 % in MHAS and 35.57 % in KLoSA. In the adjusted longitudinal multivariate analysis, an independent association was found between physical activity and MMSE score OR 0.0866 (CI 0.0266-0.1467 p-value 0.0047) in the Korean older adults, while there was no significant association in MHAS.ConclusionsPhysical activity could have a protective effect on the cognitive decline associated with aging in the Korean population.     

Improved physical performance in older adults undertaking a short-term programme of high-velocity resistance training

BACKGROUND: The age-related loss of muscle power in older adults is greater than that of muscle strength and is associated with a decline in physical performance. OBJECTIVE: To investigate the effects of a short-term high-velocity varied resistance training programme on physical performance in healthy community-dwelling adults aged 60-80 years. METHODS: Subjects undertook exercise (EX; n=15) or maintained customary activity (controls, CON; n=10) for 8 weeks. The EX group trained 2 days/week using machine weights for three sets of eight repetitions at 35, 55, and 75% of their one-repetition maximum (the maximal weight that an individual can lift once with acceptable form) for seven upper- and lower-body exercises using explosive concentric movements. RESULTS: Fourteen EX and 10 CON subjects completed the study. Dynamic muscle strength significantly increased (p=0.001) in the EX group for all exercises (from 21.4 +/- 9.6 to 82.0 +/- 59.2%, mean +/- SD) following training, as did knee extension power (p <0.01). Significant improvement occurred for the EX group in the floor rise to standing (10.4 +/- 11.5%, p=0.004), usual 6-metre walk (6.6 +/- 8.2%, p=0.010), repeated chair rise (10.4 +/- 15.6%, p=0.013), and lift and reach (25.6 +/- 12.1%, p=0.002) performance tasks but not in the CON group. CONCLUSIONS: Progressive resistance training that incorporates rapid rate-of-force development movements may be safely undertaken in healthy older adults and results in significant gains in muscle strength, muscle power, and physical performance. Such improvements could prolong functional independence and improve the quality of life.     

Promoting physical activity in older adults by education of home visitors

The objectives were to investigate in older adults (1) whether regular preventive home visits are associated with change or stability in physical activity and (2) whether education of home visitors influences stability and change in physical activity. The design was a prospective controlled randomised follow-up study with randomization at municipality level (17 intervention and 17 control municipalities) and outcomes measured at individual level. Visitors in the intervention-municipalities received regular education during 3 years. The effect of the intervention was measured by a questionnaire survey among 1,913 old persons living in the 34 municipalities at baseline and 4½-year follow-up. Changes in physical activity were measured through self-reported frequencies of vigorous physical activity. All logistic regression analyses were stratified by sex and age group (75 and 80 years old). There was no effect of receiving preventive home visits on change in physical activity among the men and among the 75-year-old women. Among the physically active 80-year-old women those who accepted and received more than four preventive home visits were more likely to go on being physically active compared to women who did not receive preventive home visits. Among the sedentary 80-year-old women those living in the intervention municipalities tended to increase their physical activity compared to the control women. These results were not seen in the old men. Preventive home visits as part of daily routine in primary care and education of home visitors and general practitioners may promote physical activity in older women.     

Effects of food form on appetite and energy intake in lean and obese young adults

OBJECTIVE: To investigate the independent effect of food form on appetite and energy intake in lean and obese adults using high carbohydrate, fat or protein food stimuli. DESIGN: Crossover dietary challenge with matched beverage and solid food forms: high carbohydrate (watermelon and watermelon juice); high protein (cheese and milk); high fat (coconut meat and coconut milk). A total of 120 lean (18-23 kg/m(2); N=60) and obese (30-35 kg/m(2); N=60) adults (18-50 years old) with stable body weight. Forty different participants (N=20 lean and 20 obese) were tested with each of the food systems. MEASUREMENTS: Appetitive sensations, food palatability and dietary intake. RESULTS: Regardless of the predominant energy source, the beverage food form elicited a weaker compensatory dietary response than the matched solid food form. Thus, total daily energy intake was significantly higher by 12.4, 19 and 15% on days the beverage forms of the high-carbohydrate, -fat and -protein foods were ingested, respectively. This was due more to a weak effect on satiety than satiation. The obese participants had higher energy intake at the lunch, including the beverage high-protein load, but overall differences between lean and obese participants were small and not systematic. CONCLUSION: Food rheology exerts an independent effect on energy intake. Dietary compensation for beverages is weaker than for solid food forms of comparable nutrient content. Thus, they pose a greater risk for promoting positive energy balance.     

Habitual physical activity in Dutch children and adolescents with haemophilia

Summary. For patients with haemophilia, a physically active lifestyle is important to maintain musculoskeletal health and to prevent chronic diseases, such as cardiovascular disease. Therefore, we studied physical activity levels, in Dutch children and adolescents with haemophilia as well as its association with aerobic fitness and joint health. Forty‐seven boys with haemophilia (aged 8–18) participated. Physical activity was measured using the Modifiable Activity Questionnaire (MAQ) and was compared with the general population. Aerobic fitness was determined using peak oxygen uptake (VO_2peak). Joint health was measured using the Haemophilia Joint Health Score (HJHS). Associations between physical activity, joint health and aerobic fitness were evaluated by correlation analysis. Subjects were 12.5 (SD 2.9) years old, had a Body Mass Index (BMI) of 19.5 (SD 3.1; z‐score 0.5) and a median HJHS score of 0 (range 0–6). Cycling, physical education and swimming were most frequently reported (86%, 69% and 50% respectively). Children with severe haemophilia participated significantly less in competitive soccer and more in swimming than children with non‐severe haemophilia. Physical activity levels were similar across haemophilia severities and comparable to the general population. VO_2peak kg^?1 was slightly lower than healthy boys (42.9 ± 8.6 vs. 46.9 ± 1.9 mL kg^?1 min^?1; P = 0.03). Joint health, aerobic fitness and physical activity showed no correlation. Dutch children with haemophilia engaged in a wide range of activities of different intensities and showed comparable levels of physical activity to the general population. Aerobic fitness was well preserved and showed no associations with physical activity levels or joint health.     

Carbohydrate intake and short-term regulation of leptin in humans

Summary The response of serum leptin to short (4 days) and prolonged (28 days) energy restriction (50 % reduction in energy intake) was determined in 18 (9 male, 9 female) moderately obese humans (body mass index 32.0 ± 0.6 kg/m² mean ± SEM), 9 of whom had mild non-insulin-dependent diabetes mellitus (NIDDM). Body composition was assessed before and at the end of the energy restriction using DEXA. The subjects lost a measured 2.6 ± 0.4 kg of body fat after 28 days and an estimated 0.3 kg at 4 days. Serum leptin fell to 64 ± 3 % of baseline levels at day 4 and further to 46 ± 4 % at day 28. In a multiple correlation analysis, the change in leptin concentration at day 4 was significantly related to the change in dietary carbohydrate intake (partial r = 0.68, p < 0.005) but not to changes in fat (r = 0.12) or protein (r = 0.02) intakes. There was a 1 : 1 relationship between the changes in leptin and dietary carbohydrate (regression slope = 1.0 ± 0.3). Gender, or the presence of NIDDM had no effects on these responses. This pronounced fall in serum leptin in association with reduced carbohydrate intake before substantial loss of body fat suggests a role for leptin in defending the body's carbohydrate stores and implicates leptin in the satiating effects of carbohydrate. Dietary or other interventions which maintain leptin levels during weight reduction may lead to improvements in weight loss. [Diabetologia (1997) 40: 348–351] Received: 29 October 1996 and in revised form: 16 December 1996