Changes In Aerobic Fitness Research Articles

Trends in aerobic fitness among Canadians, 1981 to 2007–2009

Public health surveillance systems often monitor physical activity trends, but fitness assessment is relatively rare. This study investigated secular changes in aerobic fitness among Canadian adults and children. Participants aged 8-69 years were from 2 nationally representative surveys, conducted in-home in 1981 and in mobile examination centers in 2007-2009. In both surveys, submaximal step tests using progressive age- and sex-specific exercise stages were completed after initial screening (Physical Activity Readiness Questionnaire, heart rate, blood pressure). Between surveys, the step-test protocol had been modified to reduce underestimation of fitness among fitter and older individuals. Maximal oxygen uptake was estimated for adults using validated historical and updated prediction equations, adjusted to reflect protocol differences. Because these equations are not validated for young people, maximal aerobic power was predicted at a heart rate of 200 beats·min(-1) by regressing observed heart rates on the oxygen costs of stepping for children and youth who completed at least 2 exercise stages. Overall, despite protocol differences, we found that the aerobic fitness levels of Canadians were lower in 2007-2009 than in 1981, with declines apparent in all age and both sex groups, thereby increasing the number of those at risk of adverse health outcomes. Future work is required to validate prediction equations of aerobic fitness for young people to make it possible to compare fitness levels over the lifespan and across time.

Repeated Sprints Alter Signaling Related to Mitochondrial Biogenesis in Humans

We investigated the effects of acute and chronic repeated-sprint exercise (RSE) on the skeletal muscle messenger RNA (mRNA) expression and protein abundance/phosphorylation associated with mitochondrial biogenesis. Ten healthy young adults (seven males, three females) performed the RSE trial, comprising three sets of 5 × 4-s maximal sprints on a nonmotorized treadmill, with a 20-s recovery between sprints and 4.5 min between sets. After 4 wk of repeated-sprint training, three times per week, participants repeated the RSE. A vastus lateralis muscle biopsy was obtained at rest, immediately after, and 1 and 4 h after RSE, before and after training. Venous blood lactate and glucose were measured at rest and during recovery. Real-time reverse transcriptase polymerase chain reaction and Western blot techniques were used to measure mRNA expression and protein abundance, respectively. Acute RSE increased the phosphorylation of acetyl-CoA carboxylase (86%, effect size (ES) = 1.4 ± 0.8, P < 0.001) and Ca calmodulin-dependent protein kinase II (69%, ES = 0.7 ± 0.6). Peroxisome proliferator-activated receptor γ coactivator 1α (PGC-1α; 208%, ES = 1.5 ± 0.7, P < 0.001) and nuclear respiratory factor 1 (92%, ES = 0.7 ± 0.8) mRNA expression was increased after RSE. Four weeks of training increased the abundance of PGC-1α protein at rest (33%, ES = 0.9 ± 0.7). Both acute and chronic RSE, despite only 60 s and 12 min of exercise, respectively, altered the molecular signaling associated with mitochondrial adaptations and PGC-1α mRNA expression in skeletal muscle. However, the small-to-moderate changes in resting PGC-1α protein abundance after training, together with the absence of changes in aerobic fitness, require further research to understand the functional significance of PGC-1α in response to RSE.

Influence of Change in Aerobic Fitness and Weight on Prevalence of Metabolic Syndrome

The metabolic syndrome is the clustering of several cardiometabolic risk factors that can lead to the development of coronary heart disease and type 2 diabetes. We evaluated whether a change in aerobic fitness resulting from a lifestyle intervention could significantly change the odds of metabolic syndrome prevalence. Participants (n = 810) were recruited into PREMIER, a multicenter, randomized, controlled clinical trial with outcome assessments at 6 and 18 months. The primary eligibility criterion was a diagnosis of prehypertension or stage 1 hypertension. PREMIER randomized participants to 2 lifestyle interventions, both of which included increased physical activity, or an advice-only control group. Participants completed a submaximal treadmill exercise test; we used reduction in heart rate as the measure of improved aerobic fitness. We used logistic regression to determine intervention effects on metabolic syndrome prevalence. Our models controlled for dietary pattern change. The lifestyle interventions had no significant effect on metabolic syndrome prevalence at 6 months or 18 months. When combining intervention and control groups, at 6 and 18 months, a 1-beat-per-minute reduction in heart rate was associated with a 4% reduction in prevalence of metabolic syndrome (P < .001). When we tested for weight change as a mediator, the association was no longer significant. Increased aerobic fitness may reduce prevalence of metabolic syndrome. This association appears to be mediated through concomitant weight change.

Changes in Physical Fitness, Bone Mineral Density and Body Composition During Inpatient Treatment of Underweight and Normal Weight Females with Longstanding Eating Disorders

The purpose of this study was to examine changes in aerobic fitness, muscular strength, bone mineral density (BMD) and body composition during inpatient treatment of underweight and normal weight patients with longstanding eating disorders (ED). Twenty-nine underweight (BMI < 18.5, n = 7) and normal weight (BMI ≥ 18.5, n = 22) inpatients (mean (SD) age: 31.0 (9.0) years, ED duration: 14.9 (8.8) years, duration of treatment: 16.6 (5.5) weeks) completed this prospective naturalistic study. The treatment consisted of nutritional counseling, and 2 × 60 min weekly moderate intensive physical activity in addition to psychotherapy and milieu therapy. Underweight patients aimed to increase body weight with 0.5 kg/week until the weight gain goal was reached. Aerobic fitness, muscular strength, BMD and body composition were measured at admission and discharge. Results showed an increase in mean muscular strength, total body mass, fat mass, and body fat percentage, but not aerobic capacity, among both underweight and normal weight patients. Lumbar spine BMD increased among the underweight patients, no changes were observed in BMD among the normal weight patients. Three out of seven underweight patients were still underweight at discharge, and only three out of nine patients with excessive body fat (i.e., >33%) managed to reduce body fat to normal values during treatment. These results calls for a more individualized treatment approach to achieve a more optimal body composition among both underweight and normal to overweight patients with longstanding ED.

Reduction in BMI z-score and improvement in cardiometabolic risk factors in obese children and adolescents. The Oslo Adiposity Intervention Study - a hospital/public health nurse combined treatment

BackgroundWeight loss and increased physical fitness are established approaches to reduce cardiovascular risk factors. We studied the reduction in BMI z-score associated with improvement in cardiometabolic risk factors in overweight and obese children and adolescents treated with a combined hospital/public health nurse model. We also examined how aerobic fitness influenced the results.MethodsFrom 2004-2007, 307 overweight and obese children and adolescents aged 7-17 years were referred to an outpatient hospital pediatrics clinic and evaluated by a multidisciplinary team. Together with family members, they were counseled regarding diet and physical activity at biannual clinic visits. Visits with the public health nurse at local schools or at maternal and child health centres were scheduled between the hospital consultations. Fasting blood samples were taken at baseline and after one year, and aerobic fitness (VO2peak) was measured. In the analyses, 230 subjects completing one year of follow-up by December 2008 were divided into four groups according to changes in BMI z-score: Group 1: decrease in BMI z-score≥0.23, Group 2: decrease in BMI z-score≥0.1-< 0.23, Group 3: decrease in/stable BMI z-score≥0.0-< 0.1, Group 4: increase in BMI z-score (>0.00-0.55).Results230 participants were included in the analyses (75%). Mean (SD) BMI z-score was reduced from 2.18 (0.30) to 2.05 (0.39) (p < 0.001) in the group as a whole. After adjustment for BMI z-score, waist circumference and gender, the three groups with reduced BMI z-score had a significantly greater reduction in HOMA-IR, insulin, total cholesterol, LDL cholesterol and total/HDL cholesterol ratio than the group with increased BMI z-score. Adding change in aerobic fitness to the model had little influence on the results. Even a very small reduction in BMI z-score (group 3) was associated with significantly lower insulin, total cholesterol, LDL and total/HDL cholesterol ratio. The group with the largest reduction in BMI z-score had improvements in HOMA-IR and aerobic fitness as well. An increase in BMI z-score was associated with worsening of C-peptide and total/HDL cholesterol ratio.ConclusionsEven a modest reduction in BMI z-score after one year of combined hospital/and public health nurse intervention was associated with improvement in several cardiovascular risk factors.

Clinical Pediatric Weight Management Physical Activity Program Results In Decreased Cvd Risk Factors

PURPOSE: Assessment of exercise/physical activity tolerance and indirect assessment of aerobic fitness in obese children and adolescents is necessary to improve interventions that will result in long-term, successful participation and evaluate the effectiveness of the intervention. 216 youth 58% females (F) and 51% African-Americans (AA) who were enrolled in a clinical weight management program were examined to determine changes in a 400m walk test, BMI and lipid levels before and after participation in a clinical, pediatric weight management program. METHODS: A 400m walk test was preformed as part of a clinical initial assessment and again following completion of Phase I of the weight management program. At each assessment, participants were instructed to briskly walk the measured corridor. Walk time (WT), pre-WT and post-WT HR and BP, fasting lipids, glucose, insulin and BMI was assessed at each assessment. RESULTS: Repeated measures ANOVA revealed a significant decrease in WT before & following the intervention (pretest WT = 333.5(31.6) vs posttest WT = 315.9(29.9); p<0.0001). The average length of the intervention program was 279(199) days (F=276(204), M=283(193); AA=301(206), C=253(174); NS for gender & race). There were no significant changes in BMI (pre=34.6(7.9) - post=35.2(14.1) following the intervention. However, WT (p<0.005) & BMI (p<0.02) was significantly greater prior to the intervention for AA, but change in WT & BMI was not significantly different by gender or race. Additionally, age was not associated with either the change in WT or BMI. Total cholesterol (pre=162.1(32.0) - post=156.4(31.0); p<0.001), LDL (104.8(64.5) - 96.9(27.6); p<0.09), Triglycerides (92.7(59.4) - 80.8(43.8); p<0.005) and insulin (28.4(21.8) - 23.8(13.8); p<0.005) were significantly and positively changed as a function of the intervention; only insulin was significantly greater as a function of race (AA>C) prior to the intervention (p<0.05). CONCLUSIONS: This clinical weight management intervention results in favorable changes in aerobic fitness, fasting lipids and insulin levels without a decrease in BMI. Also, the 400m walk test is a sensitive and appropriate approach for field testing populations with low exercise tolerance such as obese adolescents in a clinical setting.

Relationship of physical activity with motor skills, aerobic fitness and body fat in preschool children: a cross-sectional and longitudinal study (Ballabeina)

Adiposity, low aerobic fitness and low levels of activity are all associated with clustered cardiovascular disease risk in children and their high prevalence represents a major public health concern. The aim of this study is to investigate the relationship of objectively measured physical activity (PA) with motor skills (agility and balance), aerobic fitness and %body fat in young children. This study is a cross-sectional and longitudinal analyses using mixed linear models. Longitudinal data were adjusted for baseline outcome parameters. In all, 217 healthy preschool children (age 4-6 years, 48% boys) participated in this study. PA (accelerometers), agility (obstacle course), dynamic balance (balance beam), aerobic fitness (20-m shuttle run) and %body fat (bioelectric impedance) at baseline and 9 months later. PA was positively associated with both motor skills and aerobic fitness at baseline as well as with their longitudinal changes. Specifically, only vigorous, but not total or moderate PA, was related to changes in aerobic fitness. Higher PA was associated with less %body fat at baseline, but not with its change. Conversely, baseline motor skills, aerobic fitness or %body fat were not related to changes in PA. In young children, baseline PA was associated with improvements in motor skills and in aerobic fitness, an important determinant of cardiovascular risk.

Effect of Training Intensity Distribution on Aerobic Fitness Variables in Elite Soccer Players: A Case Study

The aim of this article was to quantify the distribution of training intensities and its effect on aerobic fitness in professional elite soccer players. Fourteen professional soccer players were observed during the prechampionship training period (6 weeks). Treadmill running speed and heart rates (HRs) at 2 and 4 mmol · L(-1) blood-lactate concentrations were assessed pre and posttraining. Training intensities were categorized using 3 HR zones: low intensity (<HR 2 mmol · L(-1)), moderate intensity (between HR 2 and 4 mmol · L(-1)), and high intensity (>HR 4 mmol · L(-1)). Analysis of the 504 individual training sessions showed that 73 ± 2.5, 19 ± 2.8, and 8 ± 1.4% of the total training time was spent at low, moderate, and high intensity, respectively (p < 0.001). Speed at 2 and 4 mmol · L(-1) significantly improved posttraining (5 and 7%, respectively, p < 0.01). Training spent at high intensity was significantly related to relative speed improvements at 2 mmol · L(-1) (r = 0.84, p < 0.001;) and 4 mmol · L(-1) (r = 0.65, p = 0.001). Players spent almost two-thirds of their training time at low intensities. However, only the time spent at high intensity (>90% of maximal HR) was related to changes in aerobic fitness. These results support the usefulness of the quantification of aerobic training load using HR. Furthermore, it stresses the effectiveness of the high-intensity training in soccer.

Ball-Sport Endurance and Sprint Test (BEAST90): Validity and Reliability of a 90-Minute Soccer Performance Test

The aim of this study was to determine the validity and reliability of a 90-minute soccer performance test: Ball-sport Endurance and Sprint Test (BEAST90). Fifteen healthy male amateur soccer players participated and attended 5 testing sessions over a 10-day period to perform physiologic and soccer-specific assessments. This included familiarization sessions and 2 full trials of the BEAST90, separated by 7 days. The total 90-minute distance, mean percent peak heart rate (HRpeak), and estimated percent peak oxygen uptake of the BEAST90 were 8,097 ± 458 m, 85 ± 5% and 82 ± 14%, respectively. Measures obtained from trial 1 and trial 2 were not significantly different (p > 0.05). Reliability of measures over 90 minutes ranged from 0.9-25.5% (% typical error). The BEAST90 protocol replicated soccer match play in terms of time, movement patterns, physical demands (volume and intensity), distances, and mean and HRpeak values, as well as having an aerobic load similar to that observed during a soccer match. Reproducibility of key physical measures during the BEAST90 were mostly high, suggesting good reliability. The BEAST90 could be used in studies that wish to determine the effects of training or nutritional interventions on prolonged intermittent physical performance.

Highlights of This Issue

The incidence rates of HCC among male Asian Americans and Pacific Islanders (API) is almost twelve times the incidence rates for non-Hispanic White men. To explore this disparity, Kwong and colleagues analyzed data from Californians of Asian ancestry with HCC. They report that cause-specific mortality was significantly higher among Laotian/Hmong and Cambodian patients. Both of these groups also had higher proportions of their populations at low socioeconomic status and Laotian/Hmong patients presented at later stages of disease. Therefore, Kwong and colleagues adjusted for time period of diagnosis, age at diagnosis, gender, geographic region, stage at diagnosis, type of surgery, and socio-economic status and found that HCC survival disparities remained for Laotian/Hmong and Cambodian patients. This study highlights the need for community-based interventions that target Laotian/Hmong and Cambodians for programs that can detect and manage HCC.Among US whites, melanoma incidence rates are higher among persons with college educations or high household incomes compared with those in the lowest categories of education or income. In addition, residing at lower latitude is often correlated with increased exposure to ultraviolet radiation (UVR). Because high SES populations often co-locate in areas of high UVR, Clarke and colleagues assessed the joint influences of SES and UVR on melanoma occurrence. They report that UVR exposure was significantly and positively associated with melanoma incidence among persons living in the top 40% (by SES) of California neighborhoods. Melanoma prevention and early detection efforts should target these high SES populations in areas of high UVR exposure.There is continued debate regarding the risks and benefits of mammography for women in their forties. Disadvantages of screening include false-positive results, or the recall of women for further investigations that do not result in a diagnosis of breast cancer. Reported false-positive rates vary widely in women aged 40 to 64. In this study, Cuckle and colleagues analyzed attendance and screening outcome data for the intervention arm of the UK Age trial. The study found that false-positive rates for women aged 40 to 48 were significantly lower than many reported rates for US women under 50. In addition, Cuckle and colleagues report that false-positive results did not discourage further screening; 89% of women experiencing false-positive screens continued with routine screening. These important findings refute the increased false-positive rates reported for women under 50.Exercise intervention could help counteract the decline in hemoglobin concentration [Hb] often observed in breast cancer patients undergoing chemotherapy. To explore this, Dolan and colleagues monitored [Hb] and aerobic fitness in breast cancer patients receiving supervised exercise training to determine if exercise influenced [Hb] in these patients. The authors report that [Hb] declined over the course of chemotherapy, regardless of exercise. There were also moderate correlations between the change in aerobic fitness and [Hb]. This study indicates that regular exercise does not protect against the decline in [Hb] associated with chemotherapy in breast cancer patients.

Hemoglobin and Aerobic Fitness Changes with Supervised Exercise Training in Breast Cancer Patients Receiving Chemotherapy

Aerobic exercise training (AET) is known to increase RBC production; however, this has not been evaluated in breast cancer patients undergoing adjuvant chemotherapy. The purpose of this study was to examine the changes in hemoglobin (Hb) levels in the Supervised Trial of Aerobic versus Resistance Training (START) and to determine its association with changes in VO(2peak). Two hundred and forty-two breast cancer patients initiating chemotherapy were randomized to usual care (n = 82), resistance exercise (RET, n = 82), or AET (n = 78) groups for the duration of their chemotherapy (median, 17 weeks). Supervised exercise was thrice weekly based on standard AET and RET prescriptions. Aerobic fitness (VO(2peak)) and Hb concentration were measured at baseline and end of chemotherapy. Regardless of the exercise group, Hb declined over the course of chemotherapy (13.4 ± 10.0 to 11.8 ± 11.5 g/dL, P < 0.01). Both AET and RET groups had significant, moderate correlations between the change in VO(2peak) and Hb (AET: r = 0.49, P < 0.001; RET: r = 0.39, P = 0.001). The results indicate that regular exercise does not protect against the decline in Hb associated with chemotherapy in breast cancer patients, but resulted in a stronger association between Hb and VO(2peak). Even with the chemotherapy-induced decline in Hb, breast cancer patients can maintain their aerobic capacity by participating in regular aerobic exercise. Further studies are required to determine safe intensity levels that may stimulate the maintenance of Hb levels in breast cancer patients.

Physiological Demands of Off-Road Vehicle Riding

The purpose of this study was to characterize the physiological demands of recreational off-road vehicle riding under typical riding conditions using habitual recreational off-road vehicle riders (n = 128). Comparisons of the physical demands of off-road vehicle riding were made between vehicle types (all-terrain vehicle (ATV) and off-road motorcycle (ORM)) to the demands of common recreational activities. Habitual riders (ATV = 56, ORM = 72) performed strength assessments before and after a representative trail ride (48 +/- 24.2 min), and ambulatory oxygen consumption was measured during one lap (24.2 +/- 11.8 min) of the ride. The mean VO2 requirement (mL x kg(-1) x min(-1)) while riding an off-road vehicle was 12.1 +/- 4.9 for ATV and 21.3 +/- 7.1 for ORM (P = 0.002), which is comparable to the VO2 required of many common recreational activities. Temporal analysis of activity intensity revealed approximately 14% of an ATV ride and 38% of an ORM ride are within the intensity range (940% VO2 reserve) required to achieve changes in aerobic fitness. Riding on a representative course also led to muscular fatigue, particularly in the upper body. On the basis of the measured metabolic demands, evidence of muscular strength requirements, and the associated caloric expenditures with off-road vehicle riding, this alternative form of activity conforms to the recommended physical activity guidelines and can be effective for achieving beneficial changes in health and fitness.

Obese children playing towards an active lifestyle

To determine whether five months of guided active play in overweight or obese children and adolescents under multi-disciplinary management for weight reduction leads to increased physical activity levels in leisure time, as well as changes in aerobic fitness and body composition. Sixty overweight or obese children and adolescents were randomly assigned to an intervention or control group. All participants received dietary advice and were encouraged to increase physical activity level. The intervention group additionally participated in 60-minute guided active play/physical activity twice a week for 5 months. Physical activity was recorded; aerobic fitness and body composition were measured at inclusion and after cessation of intervention. Physical activity level during weekend days was significantly higher for the intervention group compared with the controls after 5 months intervention (p=0.04). The mean reduction in percentage of body fat was 1.8% (95%CI: 0.6, 3.1) in the intervention group (p=0.04) and not significant among the controls (0.9 [-0.9, 2.7]). There was no change in aerobic fitness. Five months of guided active play was associated with increased physical activity levels during weekend days and reduced body fat, although weakly, in overweight and obese children and adolescents participating in multi-disciplinary weight reduction programmes.

Efficacy of submaximal field tests for monitoring aerobic fitness changes in women football players

Efficacy of submaximal field tests for monitoring aerobic fitness changes in women football players

A Yearlong Exercise Intervention Decreases CRP among Obese Postmenopausal Women

To investigate the effect of a yearlong moderate-intensity aerobic exercise intervention on C-reactive protein (CRP), serum amyloid A (SAA), and interleukin 6 (IL-6) among overweight or obese postmenopausal women. In a randomized controlled trial, 115 postmenopausal, overweight or obese, sedentary women, aged 50-75 yr were randomized to an aerobic exercise intervention of moderate-intensity (60%-75% observed maximal HR), for > or = 45 min x d(-1), 5 d x wk (n = 53), or to a 1-d x wk(-1) stretching control (n = 62), on an intent-to-treat basis. CRP, SAA, and IL-6 were measured at baseline, at 3 months, and at 12 months. From baseline to 12 months, CRP decreased 10% in exercisers and increased 12% in controls (P = 0.01); no effects were observed for SAA and IL-6. Among participants at baseline who were obese (body mass index (BMI) > or = 30 kg x m(-2)) or had abdominal obesity (waist circumference (WC) > or = 88 cm), exercise resulted in a more pronounced reduction in CRP (BMI > or = 30 kg x m(-2), P = 0.002; WC > or = 88 cm, P < 0.0001), borderline for SAA (BMI > or = 30 kg x m(-2), P = 0.08; WC > or = 88 cm, P = 0.04); no intervention effects were observed among women who did not have these characteristics. Overall, weight loss was minimal in the exercise intervention ( approximately 1.8 kg). Linear trends were observed between CRP and 12-month changes in aerobic fitness (Ptrend = 0.006), exercise adherence (Ptrend = 0.004), percentage body fat (Ptrend = 0.002), body weight (Ptrend = 0.002), WC (Ptrend = 0.02), and intra-abdominal fat (Ptrend = 0.03). A moderate-intensity exercise intervention reduced CRP for 12 months among women who were obese at baseline. These findings support the role of exercise in modulating inflammatory processes that are related to increased risk of chronic disease among obese women.

Dose-response Relationship For Controlled Aerobic Training On Vo2max Improvement In Older Adults

PURPOSE: Although much research has been conducted examining cardiorespiratory fitness (VO2max) increases with endurance training, little insight and insufficient information is individually provided regarding a quantifiable dose-response relationship for older adults. The purpose of this investigation was to identify a quantitative dose-response relationship for improvement of VO2max in sedentary older adults, resulted from controlled aerobic exercise training. METHODS: We used a systematic meta-analysis approach to synthesize the existing scientific studies regarding the effect of controlled endurance training on aerobic fitness development in older adults. Fifty-one studies were qualified for the final analysis. A total of 2522 older subjects (mean age 67.45±5.25 yrs) were included with 1511 in the exercise group and 1012 in the control. Effect sizes were calculated for training-induced improvements in VO2max. RESULTS: The pooled standardized effect size showed an average effect of 0.64±0.05 (mean±SEM, 95% CI = 0.56 to 0.73; p<0.001) for VO2max. Effect sizes indicated different responses in improvements of VO2max based on the aerobic training regimens. Training with mean intensities of 60%-65% of heart rate reserve (HRR) produced a similar effect as intensities of 75%-80% of HRR in affecting VO2max. A mean exercise duration of approximately 45 minutes per session elicited maximal gains of VO2max. Trained individuals experienced a greater VO2max increase with a mean exercise frequency of 3 to 4 d.wk-1. Greater improvement in aerobic fitness was found to be associated with a mean training length of 30 to 40 weeks with the greatest gains in those who trained for approximately 36 weeks. CONCLUSIONS: This study presented a quantifiable dose-response relationship and trends related to controlled endurance training and aerobic fitness changes in older adults. The results provide insight into the magnitude of VO2max alterations as affected by exercise dose, a function of its intensity, duration, frequency, and training length. This information can be useful in the development and prescription of effective and safe exercise programs to benefit cardiovascular healthy aging for older adults.

Exercise, Fitness, and Neurocognitive Function in Older Adults: The “Selective Improvement” and “Cardiovascular Fitness” Hypotheses

Although basic research has uncovered biological mechanisms by which exercise could maintain and enhance adult brain health, experimental human studies with older adults have produced equivocal results. This randomized clinical trial aimed to investigate the hypotheses that (a) the effects of exercise training on the performance of neurocognitive tasks in older adults is selective, influencing mainly tasks with a substantial executive control component and (b) performance in neurocognitive tasks is related to cardiorespiratory fitness. Fifty-seven older adults (65-79 years) participated in aerobic or strength-and-flexibility exercise training for 10 months. Neurocognitive tasks were selected to reflect a range from little (e.g., simple reaction time) to substantial (i.e., Stroop Word-Color conflict) executive control. Performance in tasks requiring little executive control was unaffected by participating in aerobic exercise. Improvements in Stroop Word-Color task performance were found only for the aerobic exercise group. Changes in aerobic fitness were unrelated to changes in neurocognitive function. Aerobic exercise in older adults can have a beneficial effect on the performance of speeded tasks that rely heavily on executive control. Improvements in aerobic fitness do not appear to be a prerequisite for this beneficial effect.

A Randomized Controlled Trial of the Effect of Aerobic Exercise Training on Feelings of Energy and Fatigue in Sedentary Young Adults with Persistent Fatigue

Background: There is growing evidence that chronic exercise is a promising intervention for combating feelings of low energy and fatigue. Although groups with well-defined medical conditions (for example cancer and heart disease) or unexplained fatigue syndromes consistently have reported improved feelings of energy and fatigue after chronic exercise, relatively few exercise training studies have been conducted with people who report persistent fatigue yet neither have a medical condition nor reach diagnostic criteria for an unexplained fatigue syndrome. The purpose of this investigation was to use a randomized controlled design to examine the effects of 6 weeks of chronic exercise training on feelings of energy and fatigue in sedentary, healthy young adults reporting persistent fatigue. Methods: Thirty-six healthy, young adults who reported persistent feelings of fatigue were randomly assigned to a moderate-intensity exercise, low-intensity exercise or no treatment control group. Participants in each condition then visited the exercise laboratory on 18 occasions over a 6-week period. Exercise laboratory visits occurred 3 days per week. Vigor and fatigue mood state scores were obtained at the beginning of the third exercise session each week for 6 weeks. Aerobic fitness was measured before and after intervention. Results: The effect of 6 weeks of exercise training on feelings of fatigue was dependent on exercise intensity; however, the effect on feelings of energy was similar for both the low- and moderate-intensity conditions. The changes in feelings of energy and fatigue were independent of changes in aerobic fitness. Conclusions: Six weeks of low and moderate exercise training performed by sedentary adults without a well-defined medical condition or an unexplained fatigue syndrome but reporting persistent feelings of fatigue resulted in similarly beneficial effects on feelings of energy. The effects for symptoms of fatigue were moderated by exercise intensity, and the more favorable outcome was realized with low-intensity exercise. Changes in feelings of energy and fatigue following exercise training were unrelated to changes in aerobic fitness.

Moderators of the Effects of Exercise Training in Breast Cancer Patients Receiving Chemotherapy

We have previously reported that aerobic and resistance exercise training in breast cancer patients receiving chemotherapy is beneficial but the responses were heterogeneous. Researchers recommend that clinical trials should routinely conduct and report subgroup analyses to guide the next generation of studies and inform clinical practice. PURPOSE: To examine prespecified and exploratory moderators of the effects of exercise training in the Supervised Trial of Aerobic versus Resistance Training (START). METHODS: We conducted a multicenter randomized controlled trial in Canada between 2003 and 2005 that randomized 242 breast cancer patients initiating chemotherapy to usual care (n=82), resistance exercise (RET; n=82), or aerobic exercise (AET; n=78) for the duration of their chemotherapy. Our endpoints of interest were quality of life (QoL), physical fitness, and body composition. Our primary prespecified moderator analysis was patient preference on QoL. Secondary prespecified moderator analyses were age, disease stage, and chemotherapy regimen. Marital status was explored as a moderator of QoL. RESULTS: Patient preference (p for interaction=.003) and marital status (adjusted p for interaction=.039) moderated the effects of exercise training on QoL. Participants that preferred RET improved QoL more when assigned to RET and participants that had no preference improved QoL more when assigned to AET. Unmarried participants improved QoL with exercise training but married participants did not. Age moderated aerobic fitness changes (p for interaction=.015), chemotherapy regimen moderated muscular strength gains (p for interaction=.016), and disease stage moderated lean body mass gains (p for interaction<.001) and percent body fat change (adjusted p for interaction=.055). Younger participants, those receiving non-taxane-based chemotherapies, and those with more advanced disease stage experienced the better outcomes. The interactions were not explained by differences in exercise adherence. CONCLUSION: Patient preference moderated the effects of exercise training on QoL. Other important demographic and medical factors also altered exercise training responses. These results should be confirmed in future randomized trials and, if replicated, may inform clinical practice.

The effect of exercise, training, and inactivity on insulin sensitivity in diabetics and their relatives: what is new?

Insulin resistance is a hallmark characteristic of type 2 diabetes. However, in healthy first-degree relatives of type 2 diabetics, insulin resistance is often present years before glucose intolerance or diabetes becomes clinically manifest. The mechanisms of insulin resistance involve conditions leading to an increased supply of fatty acids (e.g., high energy intake, obesity) and conditions in which the degradation/oxidation of muscular fatty acids is impaired. Several large-scale studies have documented the fact that increased physical activity can reduce or at least postpone the development of type 2 diabetes, and low physical fitness is a clear independent risk factor for the development of type 2 diabetes. The mechanisms responsible for the improvement in insulin sensitivity after exercise training have been studied extensively, but are not fully understood. This review focuses on insulin resistance in skeletal muscle and, in particular, its relation to changes in aerobic fitness in type 2 diabetics and their first-degree relatives.